Science of the Total Environment 472 (2014) 338–346
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Science of the Total Environment journal homepage: www.elsevier.com/locate/scitotenv
Value of ecosystem hydropower service and its impact on the payment for ecosystem services B. Fu a,b, Y.K. Wang a,b,⁎, P. Xu a,b, K. Yan a,b, M. Li b,c a b c
Key Laboratory of Mountain Hazards and Earth Surface Process, The Chinese Academy of Sciences, Chengdu 610041, China Institute of Mountain Hazards and Environment, The Chinese Academy of Sciences, Chengdu 610041, China Chengdu University of Technology, Chengdu 610059, China
H I G H L I G H T S • Ecosystem hydropower service is irreplaceable due to high cost of dams. • Hydropower PES requires a transition from passive protection to active protection. • A differential PES standard should be implemented for cascade development.
a r t i c l e
i n f o
Article history: Received 2 September 2013 Received in revised form 1 November 2013 Accepted 3 November 2013 Available online xxxx Keywords: Ecosystem services Water retention Hydropower Cascade development InVEST model Payment for ecosystem services
a b s t r a c t Hydropower is an important service provided by ecosystems. We surveyed all the hydropower plants in the Zagunao River Basin, Southwest China. Then, we assessed the hydropower service by using the InVEST (The Integrated Value and Tradeoff of Ecosystem Service Tools) model. Finally, we discussed the impact on ecological compensation. The results showed that: 1) hydropower service value of ecosystems in the Zagunao River Basin is 216.29 Euro/hm2 on the average, of which the high-value area with more than 475.65 Euro/hm2 is about 750.37 km2, accounting for 16.12% of the whole watershed, but it provides 53.47% of the whole watershed service value; 2) ecosystem is an ecological reservoir with a great regulation capacity. Dams cannot completely replace the reservoir water conservation function of ecosystems, and has high economic and environmental costs that must be paid as well. Compensation for water conservation services should become an important basis for ecological compensation of hydropower development. 3) In the current PES cases, the standard of compensation is generally low. Cascade development makes the value of upstream ecosystem services become more prominent, reflecting the differential rent value, and the value of ecosystem services should be based on the distribution of differentiated ecological compensation. © 2013 Published by Elsevier B.V.
1. Introduction As a renewable energy source, hydropower has attracted worldwide attention (Huang and Yan, 2009; Yüksel, 2008). The demand for energy due to China's rapid economic development has stimulated hydropower development, and thus China has become a typical one of the developing countries in energy development. Southwest China has abundant water resources, and it is becoming one of the important hydroelectric bases. Eight of the thirteen planned hydropower bases are located in this region. Of them there are large plants like those over the Jinsha River, but there are also medium-sized hydropower stations like those
⁎ Corresponding author at: Key Laboratory of Mountain Hazards and Earth Surface Process, The Chinese Academy of Sciences, Chengdu 610041, China. Tel.: + 86 28 85230627; fax: +86 28 85228557. E-mail addresses: [email protected] (B. Fu), [email protected] (Y.K. Wang). 0048-9697/$ – see front matter © 2013 Published by Elsevier B.V. http://dx.doi.org/10.1016/j.scitotenv.2013.11.015
over the Daduhe River (Huang and Yan, 2009). Cascade development has become the main mode of hydropower development. Hydropower development has not only brought about huge economic benefits, but also has caused environmental impact which cannot be ignored, involving river health (Kibler and Tullos, 2013), biodiversity conservation (Grumbine and Xu, 2011) and water safety. The most important problem is immigration (MA et al., 2011). These problems make the current hydropower development model suffer more increasing doubts, which is not conducive to the healthy development of hydropower industry. In the context of climate change, hydropower as a clean energy source to meet the energy needs of economic development has a great potential (Akpınar et al., 2011), but in order to establish a harmonious hydropower development model which can balance ecological conservation and economic development it is also needed to comprehensively understand the positive and negative effects brought about by hydropower development in the perspective of regional sustainable
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development. The key is to scientifically assess the impact of hydropower development on various stakeholders. Payment for ecosystem service (PES) is a powerful tool which provides an excellent idea for the coordination of the relationships among different interest groups in hydropower development, but the prerequisite is the scientific understanding of the relationship between ecosystem services and hydropower benefit. However, most researches put their focus on the impact of hydropower development on river ecosystem or on the assessment of ecosystem service losses (Dugan et al., 2010; Wang et al., 2010; Ziv et al., 2012). As for forests and other terrestrial ecosystems, there is a lack of quantitative evaluation of all kinds of service utilization, which thus has led to such a result that current policy and management are merely focused on how to reduce the environmental impact, as well as damages, but cannot effectively promote an integrated watershed protection, nor establish the sustainable hydropower development mode. In this paper, we surveyed the hydropower plants in the Zagunao River Basin, a main tributary of the Minjiang River in Southwest China with earlier hydropower development, and using GIS models we assessed the ecosystem function and value for hydropower, then identified the high-value area, and proposed recommendations for PES. 2. Study area
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townships etc., with a total population of about 50,000. Land use of the Zagunao River Basin is dominated by forest, shrub and grassland, with cropland and construction land accounting for 2% only (Fig. 1). Due to abundant rainfall and undulating terrain, hundreds of rivers run through this area, including the Mengtun River, the Suoluogou River and the Banzigou tributaries. So this area has become the earlier hydropower development area in Southwest China. 2.2. Hydropower development in the Zagunao River Basin The Zagunao River Basin is a region where there are more abundant hydropower resources in the upper reaches of the Minjiang River Basin. The early history of hydropower development can go back to 1958, in which the Xiazhuang plant was set up as the first hydropower station over the Mingjiang River. By now, there are more than 40 hydropower plants in this river basin (Fig. 1), with a total installed capacity of 1.12 million kilowatts. The hydropower plants are mainly located in the mainstreams and main tributaries like the Mengtun River and the Suoluogou River. The Shiziping Hydropower Station built in 2012 is the largest plant, with an installed capacity of 200,000 kW and a regulating capacity of 119 million cubic meters. In this river basin there are still five power plants under construction.
2.1. Overview of the Zagunao River Basin
3. Methods
The Zagunao River is located in the north-central Sichuan Province, a tributary of the Minjiang River with a drainage area of 4632 km2. The administrative divisions include Miyaluo, Zagunao, Xuecheng
This study is based on the Integrated Valuation of Ecosystem Services and Tradeoffs-InVEST model ecosystem utility services. The research framework is shown in Fig. 2.
Fig. 1. Land use in the Zagunao River Basin and the hydropower stations used in this study.
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Fig. 2. The framework of ecosystem hydropower service assessment.
3.1. Step 1.1: mapping of the distribution of hydropower plants
3.4. Step 2.2: assessment of the water retention function
We conducted an in-situ survey of the power stations in the Zagunao River Basin in May 2013, and determined the locations of hydroelectric dams, and acquired the relevant data on the hydropower plants, including plant type, installed capacity, storage capacity, annual generation capacity and other indicators (Fig. 3).
We used the InVEST water yield model to assess the ecosystem water retention function. This model was developed on the basis of the water balance theory, with the annual water yield (precipitation minus evapotranspiration) as the evaluation indicator for ecosystem water retention function (Kareiva et al., 2011; Swetnam et al., 2011). The evaluation results were calibrated with the annual flow data from two hydrological stations in both upper and lower reaches. According to water balance principle, water production is equivalent to precipitation minus evaporation for each grid cell:
3.2. Step 1.2: extracting of the station watershed The hydroelectric power station dam was chosen as the outlet of the station basin, and the 30-m resolution DEM was used for catchment extraction. 3.3. Step 2.1: mapping of the land use According to the survey results, most of the hydropower stations in the Zagunao River Basin had been built during the period from 2000 to 2010, hence the land-use map made in 2005 was used as the benchmarks for the evaluation of water conservation function.
Yjx ¼
AETxj Px 1− Px
ð1Þ
where, Yix is annual water yield, Px is annual precipitation for each grid cell (x), AETxj is annual evapotranspiration for each land use cell (j): AETxj 1 þ ωx Rxj ¼ : Px 1 þ ωx Rxj þ 1=Rxj
ð2Þ
Rxj is the Budyko (1974) dryness index for land use type j on grid cell x (dimensionless), and it is defined as the ratio of potential evaporation to precipitation: Rxj ¼
Fig. 3. The hydroelectric dam (Left. Dam of Xiazhuang Power Station, the first one over the Zagunao River, built in 1958; Right. The Lyye Power Station, built in 1997).
k ET0 Px
ð3Þ
where, k is the crop coefficient, i.e., the ratio of crop evapotranspiration (ET) to potential evapotranspiration (ET0). Potential evapotranspiration, ET0, means evapotranspiration under the condition that the flat ground surface is completely sheltered by specific dwarf green plants and, at the same time, soil is fully wet (Thomas, 2008). The Penman–Monteith formula is a popularly accepted
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method for potential evapotranspiration calculation, but its application is limited because a variety of parameters are required. In the areas where the data are difficult to obtain it is better to use the Modified– Hargreaves method (Droogers and Allen, 2002): 0:76 ET0 ¼ 0:0013 0:408 RA Tavg þ 17 ðTD−0:0123PÞ
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3.6. Step 4: superposition of the values from each station Runoff produced by upstream ecosystems can be used for a large number of power plants that will produce repeated value, so it is needed to superimpose a single value for multiple power plants.
ð4Þ 3.7. Step 5: identification of the high-value areas
where, ET0 is potential evapotranspiration (mm/d); RA is solar radiation at the top level of the atmosphere [MJ/(m2•d)]; Tagv is the average of the mean day maximum temperature and the mean minimum temperature (°C); TD is the difference between average day maximum temperature and the average day minimum temperature (°C). On the basis of previous studies, solar radiation at the top of the atmosphere (Rahimi Khoob, 2008) was obtained by dividing the observed average total radiation (assuming that solar radiation at the top of the atmosphere is 100%, after passing through the atmosphere, solar radiation will experience scattering, absorption and reflection, with the upward scattered portion accounting for 4%, and the atmospherically absorbed portion accounts for 21%, the cloud-absorbed portion accounts for 3%, the cloud reflected portion accounts for 23%, and the total loss accounts for about 50%). ωx is the ratio of available water by modified vegetation to precipitation (dimensionless): ωx ¼ Z
AWCx Px
ð5Þ
where: Z is the Zhang coefficient (Zhang et al., 2001), defined as a parameter for the characterization of natural climate-soil properties; AWCx is the available water; AWCx ¼ minðMaxSoilDepthx ; RootDepthx Þ PAWCx
ð6Þ
where, MaxSoilDepth is soil depth, RootDepth is root depth, PAWCx is plant available water content (refer to the method of Zhou et al., 2003): 2
PAWC ¼ 54:509−0:132 sand%−0:003 ðsand%Þ 2
−0:055silt%−0:006 ðsilt%Þ −0:738 clay% 2
ð7Þ
2
þ0:007ðclay%Þ −2:688OM% þ 0:501ðOM%Þ
where, sand is soil sand content (%); silt is soil silt content (%); clay is soil clay content (%); and OM is soil organic matter content (%). Besides the meteorological data, soil particle composition, soil bulk density, digital elevation models (DEM) and land use were required by this model. Four parameters must be prepared also, which includes evapotranspiration coefficient (ETK), root system depth, flow rate coefficient (Vel_coef) and soil saturated hydraulic conductivity. The first three parameters are based on land use types to be obtained by referring to related studies. The soil saturated hydraulic conductivity is calculated in terms of soil texture. 3.5. Step 3: calculation of the water retention service value The value of ecosystem water power generation was calculated in terms of the proportion of water retention to the flow used by the station: Vx ¼
n X wateryield
x
i¼0
Runof f i
Flowini EPi Runof f i
ð8Þ
where, Vx is the x-th ecosystem hydropower service value (Euro), Wateryieldx is the annual water yield (m3), Runoffi is the annual runoff at the dam (m3), Flowini is the runoff used by the power station (m3/s), and EP is the annual power generating revenue (Euro). The grid purchase price is determined to be 0.034 Euro/kWh according to Sichuan Price Control Administration.
The notable feature of ecosystem services is the spatial heterogeneity (Turner et al., 2012), then by protecting high-value areas one can obtain the maximum benefit at the minimum cost, and this is the current focus of ecological protection. We take the average hydropower service value and the sum of standard deviations as the threshold and in this case the area whose value is higher than this value was determined as a high-value area. 4. Results and discussion 4.1. Hydropower service of ecosystems 4.1.1. Hydropower service Hydropower service value of the Zagunao River Basin ecosystems is 216.29 Euro/hm2 on the average, with a total value of 0.99 × 108 Euro/ a. Hydropower service value has obvious spatial distribution, showing an increasing trend from lower reaches to upper reaches (Fig. 4). The high-value areas are mainly distributed in the upper reaches of the river basin, covering an area of approximately 750.37 km2 and accounting for 16.12% of the total river basin, but the high-value areas provide 53.47% value of the whole river basin. These areas are the key areas to carry out ecological protection and PES, in order to ensure the implementation of the entire river basin hydropower service. Due to the spatial heterogeneity of ecological indicators, ecosystem services value showed changes in landscape. High value areas are important for ecosystem management (Egoh et al., 2011), these area are considered as ecosystem service hotspot (Seidl and Moraes, 2000), such as landscape service hotspots identified by Hermann et al. (2013). Ecosystem services depended on the combination of a variety of ecological factors, and its variation degree was less than that of each ecological factor. Then, the hotspot distribution was related to the spatial scales, and in most situation not concentrated. But high value areas of hydropower service were relatively concentrated, reflecting the cascade development of hydropower strengthened hotspot area, and highlighting the important role of upstream ecosystems in hydropower generation. In the case of limited funds, these areas would give priority to the implementation of PES. 4.1.2. Impact of cascade development on hydropower service Although hydropower development in the Zagunao River Basin began in the 1950s of the last century, large-scale cascade development started in the 1990s. For example, the Ganbao hydropower plant was built in 1990, and then the Lvye2 hydropower station was built in 2002. By 2013, nine plants have been built over the mainstream. Before cascade development is completed, the value of ecosystem services is low. The high-value areas are located in the central part of the river basin (Fig. 5a), and when the cascade development is completed, the value of ecosystem services increases, with the high-value areas being shifted to the upper reaches of the watershed (Fig. 5b). The negative impact caused by cascade development increased with the number of plants, but the total value of ecosystem hydropower service also increased. These two opposite changes implied that human activities played an important role in ecosystem service tradeoff. Excessive use for certain services always causes other services to decrease. For instance, the European ecological assessment pointed out that the growth of the supply service brought the loss of biodiversity (Maes et al., 2012). In Loess Plateau of China, human activities
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Fig. 4. Ecosystem hydropower service distribution in Zagunao River Basin.
significantly affected the balance between regulating services and provision services (Su CH et al., 2012). Human preferential utilization for different ecosystem services changed the balance among ecosystem services, and revealed the relationship between the different stakeholders (Butler et al., 2011). The loss of ecosystem services downstream may be related to the increase of ecosystem services upstream, then these changes should be considered in PES. For any planning project, the benefits must be compared with the loss in ecosystem services (Xie et al., 2001). 4.1.3. Impact of location on hydropower service Cascade development often lasts for a long period, such as the Zagunao River development which lasted for 20 years. The impact of
hydropower plants on ecosystem hydropower service would be reflected gradually. The key is the change of relative position of hydropower service supply and demand due to cascade development. According to the differential rent theory, the realization of ecosystem services is not only related to the number of services provided by the ecosystems, but also to their locations (Robertson, 2006; Voigt, 2003). And the latter in many cases plays a more important role. Boyd and Wainger (2003) pointed out that the revenues generated by ecological functions of wetlands have an important relationship with their position in the natural landscape. Take the utility services for example. In the case of a single plant, the value of ecosystem services is mainly affected by water retention function. When cascade development is performed, runoff retained by the ecosystem can be reused by multiple
Fig. 5. Pattern of ecosystem hydropower services (a. Before cascade development; b. After cascade development).
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power plants downstream, giving rise to a higher value. Even if there is a small amount of water retention after repeated use, but there are numerous hydropower plants downstream, its value may be higher than that of the ecosystem with high water retention function. As viewed from the statistics data in Fig. 6, hydropower service value tends to change with the distance to the outlet. The overall value of hydroelectricity services tends to increase in the upstream watershed, but the decrease of hydropower value in the source areas reflects the impact of water retention function. This reflects the spatial differences between ecosystem service supply and consumption (Martín-López et al., 2009). If the supply of ecosystem services can be in accordance with the overall arrangement of hydropower cascade development, then not only a single hydropower station, but also the overall services of the watershed, can be maximized. Although it is difficult to achieve this ideal scenario, at least it provided guidance for the optimal management of the current stations.
4.2. Sources of value 4.2.1. Water retention function and hydropower benefits The realization of hydropower benefits is connected with a number of ecosystem services, mainly water retention and soil conservation. And water retention has most direct impact on hydropower benefits. Because the normal operation of a turbine needs a stable flow discharge, but runoff has strong dynamics due to climate change, the result is that in dry season, power plants have not enough flow to drive their turbines. Our survey found that the majority of power plants over the Zagunao River have about 4000 utilization hours, indicating that nearly half of the installed capacity of power plants is not brought into play. Soil conservation is an important function which is directly related to the life of water conservancy projects in the precipitation-rich areas. Such services are considered as the main basis for hydropower PES (Akpınar et al., 2011). However, soil conservation and water retention have different effects on hydropower stations. The role of ecosystem water retention function is to increase the available water for hydropower stations. Especially during the dry seasons, water retention will exert a direct impact on the effectiveness of power stations. The role of soil conservation is to reduce sedimentation effects on the operation of hydropower stations, including the reduction of reservoir capacity, dredging losses and wear and tear caused by the turbine depreciation. Trung used the data from 200 plots at a hydropower station in Vietnam to study the upstream ecosystems, thinking that the plant life could be extended for 30–50 years (Nguyen et al., 2013). Thus, although both services are important for hydropower stations, the impact is different, and ecological compensation also needs to be treated differently.
Hydriopower service value (Yuan/ha)
50000
Lugaoqiao
40000 Miyaluo
343
The Zagunao River Basin is a susceptible area of debris flow, landslides, mudslides and other geological disasters (Meng et al., 2005). Those disasters are an important source of reservoir sediments. Although soil conservation function is also very important, it is hard to distinguish different sediment resources from reservoir sedimentation, and it is still unable to accurately assess the impact of soil ecosystem protection on the maintenance of hydropower station operation. A one to one relationship between ecosystem services and ecosystem functions did not exist. The implantation of individual service was related to several ecosystem functions. For example, hydropower service was involved in water retention and soil conservation, while water supply service was related to water yield and nutrient retention. Water retention function was not completely converted to hydropower service since the supply and demand of electronic power had a strong temporal fluctuation. In the process of transferring ecosystem functions to ecosystem services, supply and demand should be considered altogether (Villamagna et al., 2013). Therefore, value of ecosystem services should be divided into actual value and potential value. Ecological compensation standards should be determined based on individual ecosystem service value accounting, also considering the contribution of each related ecosystem function in balancing the supply and demand relationship of ecosystem services, respectively.
4.2.2. Irreplaceability of ecosystem hydropower service The important feature of ecosystem services is their irreplaceability (Farley and Costanza, 2010). Compared to waterworks, hydropower plants have relatively low requirements to aquatic environment, but still cannot be completely replaced. Compared with the ecological reservoirs of watershed ecosystems, the storage capacity of a human built reservoir is too small. Take the Zagunao River for example, where there have been built 47 power plants, of which only seven have regulation capacity, with an average capacity of 1700 m3. The adjustment capacity of the largest Shiziping installed power plant is 119 million cubic meters, but the ecological storage capacity provided by ecosystems within the catchment is 979 million cubic meters, with an adjustment coefficient of 0.12 (Table 1). The construction and maintenance of project reservoirs require a high cost, for example the total investment in the construction of the Shiziping reservoir dam is 0.203 billion Euro, the cost of unit capacity is 1.7 Euro/m3. Costa Rica hydropower operation and management costs $2.5/MW. The cost of small hydropower generation in Fujian Province is 0.036 Euro/kWh (Bureau., 2008). Project life depends on the upstream reservoir ecosystem. A survey along the Zagunao River found that most reservoirs are faced with silting problems. Even in the case of diversion power plants, during floods, power plants require frequent downtime desalting, thus affecting plant output. Ecosystems do not require a lot of investment in construction, even in the case of degraded forest ecosystems. They mainly rely on natural recovery. And because they have water retention, soil conservation and other functions, the ecological benefits of water retention may be sustainably brought into play.
Shiziping
30000
Table 1 Project reservoirs and ecological reservoirs.
20000
No.
Plant
Total storage (104 m3)
Regulation storage (104 m3)
Catchment area (km2)
Water retention (mm)
Ecological storage (104 m3)
1 2 3 4 5 6 7 8
Lixian Hongye2 Hongye1 Shiziping Sangping Gucheng Xiazhuang Xuecheng
100 15.24 3.39 13,270 10.8 99 1 136
40 5.8 0 11,900 0 58 0 83
2253 1539 546 1160 4629 3830 4482 2621
151.16 150.78 155.94 150.72 139 143.21 139.45 149.94
190,715.55 129,948.24 47,680.21 97,907.71 360,321.36 307,156.81 350,008.34 220,075.93
Hongye2
10000
Ganbao Xuecheng Xiazhuang Sangping
Gucheng
0 0
20000
40000
60000
80000
100000
12000
Distance to Mingjiang mainstream (m) Fig. 6. Hydropower service value changes with distance to downstream.
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Hydroelectric power generation efficiency depends on the full realization of security and head runoff level, which determines the coordinated application of ecosystem regulation services and hydropower projects. One should take full use of water retention functions of ecosystems to form a natural ecological reservoir, so as to avoid dam construction, while the object of a construction project is to increase the hydrological head, then to improve and increase power generation efficiency. Irreplaceability of hydropower service reflects a common feature of natural ecosystem. Ecosystem services are essentially cannot be completely replaced by artificial systems (Dunbar et al., 2013). The artificial means can achieve a high strength use for ecosystem services, but integrated ecosystem services may therefore decrease. This is because ecosystem formed complex self-adjustment and adaptation ability to environmental change in a long time succession process, and cannot be exactly replicated by any artificial system (Zhang JF et al., 2005). 4.3. Hydropower service and PES 4.3.1. Ecological compensation standard for hydropower development Since stakeholders involved in hydropower service are relatively clear, PES for hydropower has found more applications in developing countries (Table 2). The first country that carried out ecological compensation for hydropower development is Costa Rica, followed by Brazil, Vietnam and other countries, but the compensation standard is generally low. Three power stations, for example, in Vietnam have a compensation of 0.125 point per kilowatt (To et al., 2012), Costa Rica's different compensation standards are 10–47 USD/hm2 (Rojas and Aylward, 2002). Guatemala case shows that the value of runoff per unit cubic meter is $0.38–$1.99/hm2 (Roumasset et al., 2010). Cheng (2010) checked the computation of ecological compensation standards for Jinping plant which is located over a tributary of the Yangtze River, and the compensation standard ultimately determined is onethousandth of electricity price. The main factor leading low compensation standards is that the formation of compensation standards is not entirely based on the value of hydropower service. For example, Costa Rica's hydropower compensation criteria are based on the costs incurred to avoid sedimentation reduction (Bernard et al., 2009). Water retention service was always used instead of the quantitative evaluation of hydropower service. But the calculated results of water retention service functions are generally small. For example, Qin (2009) used the storage capacity replacement cost method to calculate the Minjiang River ecosystem water conservation capacity and found it to be 5.3 billion cubic meters, and the per unit area value to be 7635 Euro/km2 (Qing et al., 2009), which is lower than the calculated (21,474 Euro/km2) result.
As for the replacement-cost method, the reservoir construction cost for unit water storage capacity is used to replace approximately the value of water conservation services (Li, 2008). This method is simple to use, but does not reflect the true value of water retention services of ecosystems because the water retention service value is reflected in the use of water, not just in construction and maintenance costs. In contrast, Guo (2001) used the hydroelectric power generation efficiency to calculate the total value of forest water regulation in the river basin (Guo et al., 2001). The result is more reasonable. But no spatialization is conducted in accordance with the scale of the contribution, and the impact of cascade development was neither taken into consideration. In more cases, PES for hydropower plants is mainly based on the impact of hydropower plants on the environment, and the compensation cannot fully reflect the ecological services. Other studies (Wang et al., 2010) on the impact of hydropower development in the Jiulong River, Fujian Province, , revealed that the average cost per kWh is 0.025 Euro/kWh, which is about three-quarters of tariff (Wang et al., 2010). As studied by Cheng (2010), the ecological compensation of the Jinping Hydropower Station is based on the total value of multiple ecosystem services, while the relevant environmental costs are taken into consideration. However, this confuses compensation subject and object, thus enlarging the scope of PES. The formation of ecological compensation standards is based primarily on ecosystem services, ecological protection and opportunity costs. At the same time, the willingness to pay and compensation should be taken into consideration. Since few comprehensive studies were conducted on several aspects of the relationship, the current compensation standards still have various defects. As long as the evaluation results of ecosystem services value evaluation are much higher than the willingness to pay, they are hard to be used in the formulation of compensation standards. In practice protection cost or environment cost is considered in formulating compensation standards in most cases. As a result, it did not fully reflect the principle of beneficiary pay, and the protection of the ecological compensation incentives cannot be reflected. 4.3.2. Water resources compensation and hydropower development compensation Owing to the multiple function of water (Brauman et al., 2007), PES for water supply and hydropower cannot be replaced mutually. Different types of ecosystem services should be compensated separately. The Zagunao River Basin is an important water source in Sichuan Province. Most of the water sources are supplied to the lower reaches, while satisfying their own needs, so the value can be calculated according to water use in Chengdu and Dujiangyan cities. The total amount of water resource in the upper reaches of the Minjiang River comes up to
Table 2 Cases of PES for hydropower development. Country China China
Hydropower station or watershed
Jinpin Station in Sichuan province Three stations over the Jiulongjiang River, Fujian China Supa Watershed, Yunnan province Vietnam Three stations Costa Rica /
Standard of PES
PES reason
Study
0.1% of the electric price 0.206 Yuan/kWh
Multiple ecosystem services and cost Environmental Impact
Cheng (2010) Wang et al. (2010)
1/50 the hydropower revenue 0.125 fen/kWh 0.24%–0.94% hydropower revenue
Impact of water loss and soil erosion on station life / Ecosystem services
Lu and Li (2006) To et al. (2012) Blackman and Woodward (2010) Costa Rica La Esperanza Hydropower Project 10–15 USD/ha Not considering the value of ecosystem services, especially the Rojas and Aylward (2002) difference between land uses Costa Rica San Fernando River; Volcán River; 10–47 USD/ha Ecosystem services based on alternative cost approach and Brinkman (2001); Balsa Superior River; Segundo River opportunity cost Redondo-Brenes (2006) Indonesia Sumberjaya US$250–1000 for sediment reduction Sediment reduction Leimona et al. (2009) 10%–30% Nepal Kulekhani 0.144% hydropower revenue / Leimona et al. (2009) Columbia / 3% as protection fun, 3% to the locality / Becerra and Ponce De León (1999) / Brause (2012) Mexico / $3.8446 MXN/ 103 m3 runoff
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14 billion cubic meters. The average annual flow of the Zagunao River amounts to 35 million, accounting for 1/4 of the Upper Minjiang River Basin. The total amount of water resource fees is 12.23 million Euro according to the amounts of Dujiangyan irrigation water, Chengdu domestic water and industrial water (Table 3). This figure is far below the value of hydropower generation (99.5 million Euro).
of these areas was backward, meteorological and hydrological data are lacking, and the spatial interpolation based on these limited data is difficult to reflect these spatial heterogeneity, affecting the accuracy of the model.
5. Conclusions
This study was sponsored by Chinese Academic Science 135 project: Impact of Minjiang Hydropower Development on Water Resources Safety and Western Light Talent Culture Project: Standard of Payment for Ecosystem Service based on GIS. We certify that this paper consists of original, unpublished work which is not under consideration for publication elsewhere.
Hydropower development is an important way to solve the energy demand in developing countries. In the global context of climate change, its importance is more prominent. But unscientific hydropower development causes great negative impact on the environment, thereby affecting the region's sustainable development. This requires stakeholders of hydropower development to correctly understand the relationship between protection and development, to fully consider the influence of ecosystem services on hydropower benefits, and to change the performance from passive compensation for environmental damage to active participation in watershed protection, so as to reduce the impact on the environment. Ecosystem services are irreplaceable. The construction of reservoirs can partially substitute water conservation function of ecosystems, but has a very high cost. In addition, these projects are life-limited. The full realization of hydropower generation benefits depends on how much runoff and head level, which determines the regulation of ecosystem services and the use of hydropower projects, which should go together. It is necessary to fully use water retention function of ecosystems to form a natural ecological reservoir, so as to reduce the construction of reservoir dams. And the object of construction project is to increase the hydrological head, then to improve and increase power generation efficiency. Hydropower revenue depends on the multiple services provided by ecosystems. Different ecological services will influence hydropower plants to varying degrees and in different ways. According to the principle that beneficiaries pay and saboteurs make compensation, ecological compensation will be conducted separately. Evaluation results for the Zagunao River showed that the value of ecosystem hydropower service is enormous, much higher than the currently collected water fees. However, this has not yet to be effectively compensated. Therefore, what should be firstly compensated are water conservation services, and then soil conservation functions. The current ecological compensation standard is relatively low and has no difference in space, which will affect the enthusiasm of protectors. In the watershed under cascade development, ecosystem hydropower service value shows significant spatial differences, giving rise to a differential rent. Differentiated compensation standards should be formulated on the basis of water and electricity service values. Our assessment results were limited by spatial–temporal scale. Maximization of hydroelectric power benefit relies on the meeting of the requirement of flow extracted by hydropower plants, then an accurate assessment on hydropower service needs daily runoff simulation. This requires eco-hydrological model coupled ecosystem process and hydrological process. Cascade hydropower stations are mainly distributed in the mountain areas. Due to the effect of topography, precipitation and temperature had prominent spatial heterogeneity. However, socio-economics
Table 3 Water resource fee of the Zagunao River Basin. Type 8
3
Annual water consumption (10 m ) Price (Euro/m3) Total (108 Euro)
Industrial
Domestic
Others Hydropower
12.25 0.008 0.094
1.5 0.005 0.007
5.5 0.006 0.033
156a / 0.995
a The runoff used by hydroelectric power is the sum of flows by all stations, because runoff can be reused, so the quantity of water is higher than the total annual runoff.
Conflict of interest
Acknowledgments This study was sponsored by the Chinese Academic Science 135 project: Impact of Minjiang Hydropower Development on Water Resources Safety and the Western Light Talent Culture Project: Standard of Payment for Ecosystem Service based on GIS. We used the InVEST model developed by The Natural Capital Project supported by Stanford University, WWF (World Wildlife Fund) and TNC (The Nature Conservancy). The authors would hereby like to express their sincere thanks. The authors also appreciate the language editing from Prof. XU ZL and the valuable comments from two anonymous reviewers. References Akpınar A, Kömürcü Mİ, Kankal M. Development of hydropower energy in Turkey: the case of Çoruh river basin. Renew Sust Energ Rev 2011;15:1201–9. Becerra MR, Ponce De León E. Financing the green plan (“plan verde”) in Colombia: challenges and opportunities. Workshop on financing of sustainable forest management, Croydon, UK; 1999. Bernard F, de Groot RS, Campos JJ. Valuation of tropical forest services and mechanisms to finance their conservation and sustainable use: a case study of Tapantí National Park, Costa Rica. For Policy Econ 2009;11:174–83. Blackman A, Woodward RT. User financing in a national payments for environmental services program: Costa Rican hydropower. Ecol Econ 2010;69:1626–38. Boyd J, Wainger L. Measuring ecosystem service benefits: the use of landscape analysis to evaluate environmental trades and compensation. Resources for the future discussion paper; 200302–63. Brauman KA, Daily GC, TKe Duarte, Mooney HA. The nature and value of ecosystem services: an overview highlighting hydrologic services. Annu Rev Environ Resour 2007;32:67–98. Brause S. Investigating the creation of a pilot payment for watershed services scheme in Chiapas. Mexico: Colorado State University; 2012. Brinkman W. Innovative financing mechanisms for conservation and sustainable forest management. European Tropical Forest Research. Network; 2001. Budyko MI. Climate and life. New York: Academic Press; 1974. Bureau. FPP. Report on small hydropower production runs cost–benefit investigation. http://www.fjjg.gov.cn/fjwjj/wsjgts/xhhk/webinfo/2008/08/1219391928642948. htm, 2008. [editor]. Butler JR, Wong GY, Metcalfe DJ, Honzák M, Pert PL, Rao N. An analysis of trade-offs between multiple ecosystem services and stakeholders linked to land use and water quality management in the Great Barrier Reef, Australia. Agric Ecosyst Environ 2011. http://dx.doi.org/10.1016/J.AGEE.2011.08.017. Cheng X. Research on ecological compensation theory and application of water and electricity exploitation. Southwest Jiaotong University; 2010. Droogers P, Allen RG. Estimating reference evapotranspiration under inaccurate data conditions. Irrigation and Drainage Systems 2002;16:33–45. Dugan PJ, Barlow C, Agostinho AA, Baran E, Cada GF, Chen D, et al. Fish migration, dams, and loss of ecosystem services in the Mekong basin. Ambio 2010;39:344–8. Dunbar MB, Panagos P, Montanarella L. European perspective of ecosystem services and related policies. Integr Environ Assess Manag 2013;9:231–6. Egoh BN, Reyers B, Rouget M, Richardson DM. Identifying priority areas for ecosystem service management in South African grasslands. J Environ Manage 2011;92: 1642–50. Farley J, Costanza R. Payments for ecosystem services: from local to global. Ecol Econ 2010;69:2060–8. Grumbine RE, Xu J. Mekong hydropower development. Science 2011;332:178–9. Guo Z, Xiao X, Gan Y, Zheng Y. Ecosystem functions, services and their values—a case study in Xingshan County of China. Ecol Econ 2001;38:141–54. Hermann A, Kuttner M, Hainz-Renetzeder C, Konkoly-Gyuró É, Tirászi Á, Brandenburg C. Assessment framework for landscape services in European cultural landscapes: an Austrian Hungarian case study. Ecol Indic 2013. http://dx.doi.org/10.1016/j.ecolind.2013.01.019. Huang H, Yan Z. Present situation and future prospect of hydropower in China. Renew Sust Energ Rev 2009;13:1652–6.
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Contents lists available at ScienceDirect
Science of the Total Environment journal homepage: www.elsevier.com/locate/scitotenv
Value of ecosystem hydropower service and its impact on the payment for ecosystem services B. Fu a,b, Y.K. Wang a,b,⁎, P. Xu a,b, K. Yan a,b, M. Li b,c a b c
Key Laboratory of Mountain Hazards and Earth Surface Process, The Chinese Academy of Sciences, Chengdu 610041, China Institute of Mountain Hazards and Environment, The Chinese Academy of Sciences, Chengdu 610041, China Chengdu University of Technology, Chengdu 610059, China
H I G H L I G H T S • Ecosystem hydropower service is irreplaceable due to high cost of dams. • Hydropower PES requires a transition from passive protection to active protection. • A differential PES standard should be implemented for cascade development.
a r t i c l e
i n f o
Article history: Received 2 September 2013 Received in revised form 1 November 2013 Accepted 3 November 2013 Available online xxxx Keywords: Ecosystem services Water retention Hydropower Cascade development InVEST model Payment for ecosystem services
a b s t r a c t Hydropower is an important service provided by ecosystems. We surveyed all the hydropower plants in the Zagunao River Basin, Southwest China. Then, we assessed the hydropower service by using the InVEST (The Integrated Value and Tradeoff of Ecosystem Service Tools) model. Finally, we discussed the impact on ecological compensation. The results showed that: 1) hydropower service value of ecosystems in the Zagunao River Basin is 216.29 Euro/hm2 on the average, of which the high-value area with more than 475.65 Euro/hm2 is about 750.37 km2, accounting for 16.12% of the whole watershed, but it provides 53.47% of the whole watershed service value; 2) ecosystem is an ecological reservoir with a great regulation capacity. Dams cannot completely replace the reservoir water conservation function of ecosystems, and has high economic and environmental costs that must be paid as well. Compensation for water conservation services should become an important basis for ecological compensation of hydropower development. 3) In the current PES cases, the standard of compensation is generally low. Cascade development makes the value of upstream ecosystem services become more prominent, reflecting the differential rent value, and the value of ecosystem services should be based on the distribution of differentiated ecological compensation. © 2013 Published by Elsevier B.V.
1. Introduction As a renewable energy source, hydropower has attracted worldwide attention (Huang and Yan, 2009; Yüksel, 2008). The demand for energy due to China's rapid economic development has stimulated hydropower development, and thus China has become a typical one of the developing countries in energy development. Southwest China has abundant water resources, and it is becoming one of the important hydroelectric bases. Eight of the thirteen planned hydropower bases are located in this region. Of them there are large plants like those over the Jinsha River, but there are also medium-sized hydropower stations like those
⁎ Corresponding author at: Key Laboratory of Mountain Hazards and Earth Surface Process, The Chinese Academy of Sciences, Chengdu 610041, China. Tel.: + 86 28 85230627; fax: +86 28 85228557. E-mail addresses: [email protected] (B. Fu), [email protected] (Y.K. Wang). 0048-9697/$ – see front matter © 2013 Published by Elsevier B.V. http://dx.doi.org/10.1016/j.scitotenv.2013.11.015
over the Daduhe River (Huang and Yan, 2009). Cascade development has become the main mode of hydropower development. Hydropower development has not only brought about huge economic benefits, but also has caused environmental impact which cannot be ignored, involving river health (Kibler and Tullos, 2013), biodiversity conservation (Grumbine and Xu, 2011) and water safety. The most important problem is immigration (MA et al., 2011). These problems make the current hydropower development model suffer more increasing doubts, which is not conducive to the healthy development of hydropower industry. In the context of climate change, hydropower as a clean energy source to meet the energy needs of economic development has a great potential (Akpınar et al., 2011), but in order to establish a harmonious hydropower development model which can balance ecological conservation and economic development it is also needed to comprehensively understand the positive and negative effects brought about by hydropower development in the perspective of regional sustainable
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development. The key is to scientifically assess the impact of hydropower development on various stakeholders. Payment for ecosystem service (PES) is a powerful tool which provides an excellent idea for the coordination of the relationships among different interest groups in hydropower development, but the prerequisite is the scientific understanding of the relationship between ecosystem services and hydropower benefit. However, most researches put their focus on the impact of hydropower development on river ecosystem or on the assessment of ecosystem service losses (Dugan et al., 2010; Wang et al., 2010; Ziv et al., 2012). As for forests and other terrestrial ecosystems, there is a lack of quantitative evaluation of all kinds of service utilization, which thus has led to such a result that current policy and management are merely focused on how to reduce the environmental impact, as well as damages, but cannot effectively promote an integrated watershed protection, nor establish the sustainable hydropower development mode. In this paper, we surveyed the hydropower plants in the Zagunao River Basin, a main tributary of the Minjiang River in Southwest China with earlier hydropower development, and using GIS models we assessed the ecosystem function and value for hydropower, then identified the high-value area, and proposed recommendations for PES. 2. Study area
339
townships etc., with a total population of about 50,000. Land use of the Zagunao River Basin is dominated by forest, shrub and grassland, with cropland and construction land accounting for 2% only (Fig. 1). Due to abundant rainfall and undulating terrain, hundreds of rivers run through this area, including the Mengtun River, the Suoluogou River and the Banzigou tributaries. So this area has become the earlier hydropower development area in Southwest China. 2.2. Hydropower development in the Zagunao River Basin The Zagunao River Basin is a region where there are more abundant hydropower resources in the upper reaches of the Minjiang River Basin. The early history of hydropower development can go back to 1958, in which the Xiazhuang plant was set up as the first hydropower station over the Mingjiang River. By now, there are more than 40 hydropower plants in this river basin (Fig. 1), with a total installed capacity of 1.12 million kilowatts. The hydropower plants are mainly located in the mainstreams and main tributaries like the Mengtun River and the Suoluogou River. The Shiziping Hydropower Station built in 2012 is the largest plant, with an installed capacity of 200,000 kW and a regulating capacity of 119 million cubic meters. In this river basin there are still five power plants under construction.
2.1. Overview of the Zagunao River Basin
3. Methods
The Zagunao River is located in the north-central Sichuan Province, a tributary of the Minjiang River with a drainage area of 4632 km2. The administrative divisions include Miyaluo, Zagunao, Xuecheng
This study is based on the Integrated Valuation of Ecosystem Services and Tradeoffs-InVEST model ecosystem utility services. The research framework is shown in Fig. 2.
Fig. 1. Land use in the Zagunao River Basin and the hydropower stations used in this study.
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Fig. 2. The framework of ecosystem hydropower service assessment.
3.1. Step 1.1: mapping of the distribution of hydropower plants
3.4. Step 2.2: assessment of the water retention function
We conducted an in-situ survey of the power stations in the Zagunao River Basin in May 2013, and determined the locations of hydroelectric dams, and acquired the relevant data on the hydropower plants, including plant type, installed capacity, storage capacity, annual generation capacity and other indicators (Fig. 3).
We used the InVEST water yield model to assess the ecosystem water retention function. This model was developed on the basis of the water balance theory, with the annual water yield (precipitation minus evapotranspiration) as the evaluation indicator for ecosystem water retention function (Kareiva et al., 2011; Swetnam et al., 2011). The evaluation results were calibrated with the annual flow data from two hydrological stations in both upper and lower reaches. According to water balance principle, water production is equivalent to precipitation minus evaporation for each grid cell:
3.2. Step 1.2: extracting of the station watershed The hydroelectric power station dam was chosen as the outlet of the station basin, and the 30-m resolution DEM was used for catchment extraction. 3.3. Step 2.1: mapping of the land use According to the survey results, most of the hydropower stations in the Zagunao River Basin had been built during the period from 2000 to 2010, hence the land-use map made in 2005 was used as the benchmarks for the evaluation of water conservation function.
Yjx ¼
AETxj Px 1− Px
ð1Þ
where, Yix is annual water yield, Px is annual precipitation for each grid cell (x), AETxj is annual evapotranspiration for each land use cell (j): AETxj 1 þ ωx Rxj ¼ : Px 1 þ ωx Rxj þ 1=Rxj
ð2Þ
Rxj is the Budyko (1974) dryness index for land use type j on grid cell x (dimensionless), and it is defined as the ratio of potential evaporation to precipitation: Rxj ¼
Fig. 3. The hydroelectric dam (Left. Dam of Xiazhuang Power Station, the first one over the Zagunao River, built in 1958; Right. The Lyye Power Station, built in 1997).
k ET0 Px
ð3Þ
where, k is the crop coefficient, i.e., the ratio of crop evapotranspiration (ET) to potential evapotranspiration (ET0). Potential evapotranspiration, ET0, means evapotranspiration under the condition that the flat ground surface is completely sheltered by specific dwarf green plants and, at the same time, soil is fully wet (Thomas, 2008). The Penman–Monteith formula is a popularly accepted
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method for potential evapotranspiration calculation, but its application is limited because a variety of parameters are required. In the areas where the data are difficult to obtain it is better to use the Modified– Hargreaves method (Droogers and Allen, 2002): 0:76 ET0 ¼ 0:0013 0:408 RA Tavg þ 17 ðTD−0:0123PÞ
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3.6. Step 4: superposition of the values from each station Runoff produced by upstream ecosystems can be used for a large number of power plants that will produce repeated value, so it is needed to superimpose a single value for multiple power plants.
ð4Þ 3.7. Step 5: identification of the high-value areas
where, ET0 is potential evapotranspiration (mm/d); RA is solar radiation at the top level of the atmosphere [MJ/(m2•d)]; Tagv is the average of the mean day maximum temperature and the mean minimum temperature (°C); TD is the difference between average day maximum temperature and the average day minimum temperature (°C). On the basis of previous studies, solar radiation at the top of the atmosphere (Rahimi Khoob, 2008) was obtained by dividing the observed average total radiation (assuming that solar radiation at the top of the atmosphere is 100%, after passing through the atmosphere, solar radiation will experience scattering, absorption and reflection, with the upward scattered portion accounting for 4%, and the atmospherically absorbed portion accounts for 21%, the cloud-absorbed portion accounts for 3%, the cloud reflected portion accounts for 23%, and the total loss accounts for about 50%). ωx is the ratio of available water by modified vegetation to precipitation (dimensionless): ωx ¼ Z
AWCx Px
ð5Þ
where: Z is the Zhang coefficient (Zhang et al., 2001), defined as a parameter for the characterization of natural climate-soil properties; AWCx is the available water; AWCx ¼ minðMaxSoilDepthx ; RootDepthx Þ PAWCx
ð6Þ
where, MaxSoilDepth is soil depth, RootDepth is root depth, PAWCx is plant available water content (refer to the method of Zhou et al., 2003): 2
PAWC ¼ 54:509−0:132 sand%−0:003 ðsand%Þ 2
−0:055silt%−0:006 ðsilt%Þ −0:738 clay% 2
ð7Þ
2
þ0:007ðclay%Þ −2:688OM% þ 0:501ðOM%Þ
where, sand is soil sand content (%); silt is soil silt content (%); clay is soil clay content (%); and OM is soil organic matter content (%). Besides the meteorological data, soil particle composition, soil bulk density, digital elevation models (DEM) and land use were required by this model. Four parameters must be prepared also, which includes evapotranspiration coefficient (ETK), root system depth, flow rate coefficient (Vel_coef) and soil saturated hydraulic conductivity. The first three parameters are based on land use types to be obtained by referring to related studies. The soil saturated hydraulic conductivity is calculated in terms of soil texture. 3.5. Step 3: calculation of the water retention service value The value of ecosystem water power generation was calculated in terms of the proportion of water retention to the flow used by the station: Vx ¼
n X wateryield
x
i¼0
Runof f i
Flowini EPi Runof f i
ð8Þ
where, Vx is the x-th ecosystem hydropower service value (Euro), Wateryieldx is the annual water yield (m3), Runoffi is the annual runoff at the dam (m3), Flowini is the runoff used by the power station (m3/s), and EP is the annual power generating revenue (Euro). The grid purchase price is determined to be 0.034 Euro/kWh according to Sichuan Price Control Administration.
The notable feature of ecosystem services is the spatial heterogeneity (Turner et al., 2012), then by protecting high-value areas one can obtain the maximum benefit at the minimum cost, and this is the current focus of ecological protection. We take the average hydropower service value and the sum of standard deviations as the threshold and in this case the area whose value is higher than this value was determined as a high-value area. 4. Results and discussion 4.1. Hydropower service of ecosystems 4.1.1. Hydropower service Hydropower service value of the Zagunao River Basin ecosystems is 216.29 Euro/hm2 on the average, with a total value of 0.99 × 108 Euro/ a. Hydropower service value has obvious spatial distribution, showing an increasing trend from lower reaches to upper reaches (Fig. 4). The high-value areas are mainly distributed in the upper reaches of the river basin, covering an area of approximately 750.37 km2 and accounting for 16.12% of the total river basin, but the high-value areas provide 53.47% value of the whole river basin. These areas are the key areas to carry out ecological protection and PES, in order to ensure the implementation of the entire river basin hydropower service. Due to the spatial heterogeneity of ecological indicators, ecosystem services value showed changes in landscape. High value areas are important for ecosystem management (Egoh et al., 2011), these area are considered as ecosystem service hotspot (Seidl and Moraes, 2000), such as landscape service hotspots identified by Hermann et al. (2013). Ecosystem services depended on the combination of a variety of ecological factors, and its variation degree was less than that of each ecological factor. Then, the hotspot distribution was related to the spatial scales, and in most situation not concentrated. But high value areas of hydropower service were relatively concentrated, reflecting the cascade development of hydropower strengthened hotspot area, and highlighting the important role of upstream ecosystems in hydropower generation. In the case of limited funds, these areas would give priority to the implementation of PES. 4.1.2. Impact of cascade development on hydropower service Although hydropower development in the Zagunao River Basin began in the 1950s of the last century, large-scale cascade development started in the 1990s. For example, the Ganbao hydropower plant was built in 1990, and then the Lvye2 hydropower station was built in 2002. By 2013, nine plants have been built over the mainstream. Before cascade development is completed, the value of ecosystem services is low. The high-value areas are located in the central part of the river basin (Fig. 5a), and when the cascade development is completed, the value of ecosystem services increases, with the high-value areas being shifted to the upper reaches of the watershed (Fig. 5b). The negative impact caused by cascade development increased with the number of plants, but the total value of ecosystem hydropower service also increased. These two opposite changes implied that human activities played an important role in ecosystem service tradeoff. Excessive use for certain services always causes other services to decrease. For instance, the European ecological assessment pointed out that the growth of the supply service brought the loss of biodiversity (Maes et al., 2012). In Loess Plateau of China, human activities
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Fig. 4. Ecosystem hydropower service distribution in Zagunao River Basin.
significantly affected the balance between regulating services and provision services (Su CH et al., 2012). Human preferential utilization for different ecosystem services changed the balance among ecosystem services, and revealed the relationship between the different stakeholders (Butler et al., 2011). The loss of ecosystem services downstream may be related to the increase of ecosystem services upstream, then these changes should be considered in PES. For any planning project, the benefits must be compared with the loss in ecosystem services (Xie et al., 2001). 4.1.3. Impact of location on hydropower service Cascade development often lasts for a long period, such as the Zagunao River development which lasted for 20 years. The impact of
hydropower plants on ecosystem hydropower service would be reflected gradually. The key is the change of relative position of hydropower service supply and demand due to cascade development. According to the differential rent theory, the realization of ecosystem services is not only related to the number of services provided by the ecosystems, but also to their locations (Robertson, 2006; Voigt, 2003). And the latter in many cases plays a more important role. Boyd and Wainger (2003) pointed out that the revenues generated by ecological functions of wetlands have an important relationship with their position in the natural landscape. Take the utility services for example. In the case of a single plant, the value of ecosystem services is mainly affected by water retention function. When cascade development is performed, runoff retained by the ecosystem can be reused by multiple
Fig. 5. Pattern of ecosystem hydropower services (a. Before cascade development; b. After cascade development).
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power plants downstream, giving rise to a higher value. Even if there is a small amount of water retention after repeated use, but there are numerous hydropower plants downstream, its value may be higher than that of the ecosystem with high water retention function. As viewed from the statistics data in Fig. 6, hydropower service value tends to change with the distance to the outlet. The overall value of hydroelectricity services tends to increase in the upstream watershed, but the decrease of hydropower value in the source areas reflects the impact of water retention function. This reflects the spatial differences between ecosystem service supply and consumption (Martín-López et al., 2009). If the supply of ecosystem services can be in accordance with the overall arrangement of hydropower cascade development, then not only a single hydropower station, but also the overall services of the watershed, can be maximized. Although it is difficult to achieve this ideal scenario, at least it provided guidance for the optimal management of the current stations.
4.2. Sources of value 4.2.1. Water retention function and hydropower benefits The realization of hydropower benefits is connected with a number of ecosystem services, mainly water retention and soil conservation. And water retention has most direct impact on hydropower benefits. Because the normal operation of a turbine needs a stable flow discharge, but runoff has strong dynamics due to climate change, the result is that in dry season, power plants have not enough flow to drive their turbines. Our survey found that the majority of power plants over the Zagunao River have about 4000 utilization hours, indicating that nearly half of the installed capacity of power plants is not brought into play. Soil conservation is an important function which is directly related to the life of water conservancy projects in the precipitation-rich areas. Such services are considered as the main basis for hydropower PES (Akpınar et al., 2011). However, soil conservation and water retention have different effects on hydropower stations. The role of ecosystem water retention function is to increase the available water for hydropower stations. Especially during the dry seasons, water retention will exert a direct impact on the effectiveness of power stations. The role of soil conservation is to reduce sedimentation effects on the operation of hydropower stations, including the reduction of reservoir capacity, dredging losses and wear and tear caused by the turbine depreciation. Trung used the data from 200 plots at a hydropower station in Vietnam to study the upstream ecosystems, thinking that the plant life could be extended for 30–50 years (Nguyen et al., 2013). Thus, although both services are important for hydropower stations, the impact is different, and ecological compensation also needs to be treated differently.
Hydriopower service value (Yuan/ha)
50000
Lugaoqiao
40000 Miyaluo
343
The Zagunao River Basin is a susceptible area of debris flow, landslides, mudslides and other geological disasters (Meng et al., 2005). Those disasters are an important source of reservoir sediments. Although soil conservation function is also very important, it is hard to distinguish different sediment resources from reservoir sedimentation, and it is still unable to accurately assess the impact of soil ecosystem protection on the maintenance of hydropower station operation. A one to one relationship between ecosystem services and ecosystem functions did not exist. The implantation of individual service was related to several ecosystem functions. For example, hydropower service was involved in water retention and soil conservation, while water supply service was related to water yield and nutrient retention. Water retention function was not completely converted to hydropower service since the supply and demand of electronic power had a strong temporal fluctuation. In the process of transferring ecosystem functions to ecosystem services, supply and demand should be considered altogether (Villamagna et al., 2013). Therefore, value of ecosystem services should be divided into actual value and potential value. Ecological compensation standards should be determined based on individual ecosystem service value accounting, also considering the contribution of each related ecosystem function in balancing the supply and demand relationship of ecosystem services, respectively.
4.2.2. Irreplaceability of ecosystem hydropower service The important feature of ecosystem services is their irreplaceability (Farley and Costanza, 2010). Compared to waterworks, hydropower plants have relatively low requirements to aquatic environment, but still cannot be completely replaced. Compared with the ecological reservoirs of watershed ecosystems, the storage capacity of a human built reservoir is too small. Take the Zagunao River for example, where there have been built 47 power plants, of which only seven have regulation capacity, with an average capacity of 1700 m3. The adjustment capacity of the largest Shiziping installed power plant is 119 million cubic meters, but the ecological storage capacity provided by ecosystems within the catchment is 979 million cubic meters, with an adjustment coefficient of 0.12 (Table 1). The construction and maintenance of project reservoirs require a high cost, for example the total investment in the construction of the Shiziping reservoir dam is 0.203 billion Euro, the cost of unit capacity is 1.7 Euro/m3. Costa Rica hydropower operation and management costs $2.5/MW. The cost of small hydropower generation in Fujian Province is 0.036 Euro/kWh (Bureau., 2008). Project life depends on the upstream reservoir ecosystem. A survey along the Zagunao River found that most reservoirs are faced with silting problems. Even in the case of diversion power plants, during floods, power plants require frequent downtime desalting, thus affecting plant output. Ecosystems do not require a lot of investment in construction, even in the case of degraded forest ecosystems. They mainly rely on natural recovery. And because they have water retention, soil conservation and other functions, the ecological benefits of water retention may be sustainably brought into play.
Shiziping
30000
Table 1 Project reservoirs and ecological reservoirs.
20000
No.
Plant
Total storage (104 m3)
Regulation storage (104 m3)
Catchment area (km2)
Water retention (mm)
Ecological storage (104 m3)
1 2 3 4 5 6 7 8
Lixian Hongye2 Hongye1 Shiziping Sangping Gucheng Xiazhuang Xuecheng
100 15.24 3.39 13,270 10.8 99 1 136
40 5.8 0 11,900 0 58 0 83
2253 1539 546 1160 4629 3830 4482 2621
151.16 150.78 155.94 150.72 139 143.21 139.45 149.94
190,715.55 129,948.24 47,680.21 97,907.71 360,321.36 307,156.81 350,008.34 220,075.93
Hongye2
10000
Ganbao Xuecheng Xiazhuang Sangping
Gucheng
0 0
20000
40000
60000
80000
100000
12000
Distance to Mingjiang mainstream (m) Fig. 6. Hydropower service value changes with distance to downstream.
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Hydroelectric power generation efficiency depends on the full realization of security and head runoff level, which determines the coordinated application of ecosystem regulation services and hydropower projects. One should take full use of water retention functions of ecosystems to form a natural ecological reservoir, so as to avoid dam construction, while the object of a construction project is to increase the hydrological head, then to improve and increase power generation efficiency. Irreplaceability of hydropower service reflects a common feature of natural ecosystem. Ecosystem services are essentially cannot be completely replaced by artificial systems (Dunbar et al., 2013). The artificial means can achieve a high strength use for ecosystem services, but integrated ecosystem services may therefore decrease. This is because ecosystem formed complex self-adjustment and adaptation ability to environmental change in a long time succession process, and cannot be exactly replicated by any artificial system (Zhang JF et al., 2005). 4.3. Hydropower service and PES 4.3.1. Ecological compensation standard for hydropower development Since stakeholders involved in hydropower service are relatively clear, PES for hydropower has found more applications in developing countries (Table 2). The first country that carried out ecological compensation for hydropower development is Costa Rica, followed by Brazil, Vietnam and other countries, but the compensation standard is generally low. Three power stations, for example, in Vietnam have a compensation of 0.125 point per kilowatt (To et al., 2012), Costa Rica's different compensation standards are 10–47 USD/hm2 (Rojas and Aylward, 2002). Guatemala case shows that the value of runoff per unit cubic meter is $0.38–$1.99/hm2 (Roumasset et al., 2010). Cheng (2010) checked the computation of ecological compensation standards for Jinping plant which is located over a tributary of the Yangtze River, and the compensation standard ultimately determined is onethousandth of electricity price. The main factor leading low compensation standards is that the formation of compensation standards is not entirely based on the value of hydropower service. For example, Costa Rica's hydropower compensation criteria are based on the costs incurred to avoid sedimentation reduction (Bernard et al., 2009). Water retention service was always used instead of the quantitative evaluation of hydropower service. But the calculated results of water retention service functions are generally small. For example, Qin (2009) used the storage capacity replacement cost method to calculate the Minjiang River ecosystem water conservation capacity and found it to be 5.3 billion cubic meters, and the per unit area value to be 7635 Euro/km2 (Qing et al., 2009), which is lower than the calculated (21,474 Euro/km2) result.
As for the replacement-cost method, the reservoir construction cost for unit water storage capacity is used to replace approximately the value of water conservation services (Li, 2008). This method is simple to use, but does not reflect the true value of water retention services of ecosystems because the water retention service value is reflected in the use of water, not just in construction and maintenance costs. In contrast, Guo (2001) used the hydroelectric power generation efficiency to calculate the total value of forest water regulation in the river basin (Guo et al., 2001). The result is more reasonable. But no spatialization is conducted in accordance with the scale of the contribution, and the impact of cascade development was neither taken into consideration. In more cases, PES for hydropower plants is mainly based on the impact of hydropower plants on the environment, and the compensation cannot fully reflect the ecological services. Other studies (Wang et al., 2010) on the impact of hydropower development in the Jiulong River, Fujian Province, , revealed that the average cost per kWh is 0.025 Euro/kWh, which is about three-quarters of tariff (Wang et al., 2010). As studied by Cheng (2010), the ecological compensation of the Jinping Hydropower Station is based on the total value of multiple ecosystem services, while the relevant environmental costs are taken into consideration. However, this confuses compensation subject and object, thus enlarging the scope of PES. The formation of ecological compensation standards is based primarily on ecosystem services, ecological protection and opportunity costs. At the same time, the willingness to pay and compensation should be taken into consideration. Since few comprehensive studies were conducted on several aspects of the relationship, the current compensation standards still have various defects. As long as the evaluation results of ecosystem services value evaluation are much higher than the willingness to pay, they are hard to be used in the formulation of compensation standards. In practice protection cost or environment cost is considered in formulating compensation standards in most cases. As a result, it did not fully reflect the principle of beneficiary pay, and the protection of the ecological compensation incentives cannot be reflected. 4.3.2. Water resources compensation and hydropower development compensation Owing to the multiple function of water (Brauman et al., 2007), PES for water supply and hydropower cannot be replaced mutually. Different types of ecosystem services should be compensated separately. The Zagunao River Basin is an important water source in Sichuan Province. Most of the water sources are supplied to the lower reaches, while satisfying their own needs, so the value can be calculated according to water use in Chengdu and Dujiangyan cities. The total amount of water resource in the upper reaches of the Minjiang River comes up to
Table 2 Cases of PES for hydropower development. Country China China
Hydropower station or watershed
Jinpin Station in Sichuan province Three stations over the Jiulongjiang River, Fujian China Supa Watershed, Yunnan province Vietnam Three stations Costa Rica /
Standard of PES
PES reason
Study
0.1% of the electric price 0.206 Yuan/kWh
Multiple ecosystem services and cost Environmental Impact
Cheng (2010) Wang et al. (2010)
1/50 the hydropower revenue 0.125 fen/kWh 0.24%–0.94% hydropower revenue
Impact of water loss and soil erosion on station life / Ecosystem services
Lu and Li (2006) To et al. (2012) Blackman and Woodward (2010) Costa Rica La Esperanza Hydropower Project 10–15 USD/ha Not considering the value of ecosystem services, especially the Rojas and Aylward (2002) difference between land uses Costa Rica San Fernando River; Volcán River; 10–47 USD/ha Ecosystem services based on alternative cost approach and Brinkman (2001); Balsa Superior River; Segundo River opportunity cost Redondo-Brenes (2006) Indonesia Sumberjaya US$250–1000 for sediment reduction Sediment reduction Leimona et al. (2009) 10%–30% Nepal Kulekhani 0.144% hydropower revenue / Leimona et al. (2009) Columbia / 3% as protection fun, 3% to the locality / Becerra and Ponce De León (1999) / Brause (2012) Mexico / $3.8446 MXN/ 103 m3 runoff
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14 billion cubic meters. The average annual flow of the Zagunao River amounts to 35 million, accounting for 1/4 of the Upper Minjiang River Basin. The total amount of water resource fees is 12.23 million Euro according to the amounts of Dujiangyan irrigation water, Chengdu domestic water and industrial water (Table 3). This figure is far below the value of hydropower generation (99.5 million Euro).
of these areas was backward, meteorological and hydrological data are lacking, and the spatial interpolation based on these limited data is difficult to reflect these spatial heterogeneity, affecting the accuracy of the model.
5. Conclusions
This study was sponsored by Chinese Academic Science 135 project: Impact of Minjiang Hydropower Development on Water Resources Safety and Western Light Talent Culture Project: Standard of Payment for Ecosystem Service based on GIS. We certify that this paper consists of original, unpublished work which is not under consideration for publication elsewhere.
Hydropower development is an important way to solve the energy demand in developing countries. In the global context of climate change, its importance is more prominent. But unscientific hydropower development causes great negative impact on the environment, thereby affecting the region's sustainable development. This requires stakeholders of hydropower development to correctly understand the relationship between protection and development, to fully consider the influence of ecosystem services on hydropower benefits, and to change the performance from passive compensation for environmental damage to active participation in watershed protection, so as to reduce the impact on the environment. Ecosystem services are irreplaceable. The construction of reservoirs can partially substitute water conservation function of ecosystems, but has a very high cost. In addition, these projects are life-limited. The full realization of hydropower generation benefits depends on how much runoff and head level, which determines the regulation of ecosystem services and the use of hydropower projects, which should go together. It is necessary to fully use water retention function of ecosystems to form a natural ecological reservoir, so as to reduce the construction of reservoir dams. And the object of construction project is to increase the hydrological head, then to improve and increase power generation efficiency. Hydropower revenue depends on the multiple services provided by ecosystems. Different ecological services will influence hydropower plants to varying degrees and in different ways. According to the principle that beneficiaries pay and saboteurs make compensation, ecological compensation will be conducted separately. Evaluation results for the Zagunao River showed that the value of ecosystem hydropower service is enormous, much higher than the currently collected water fees. However, this has not yet to be effectively compensated. Therefore, what should be firstly compensated are water conservation services, and then soil conservation functions. The current ecological compensation standard is relatively low and has no difference in space, which will affect the enthusiasm of protectors. In the watershed under cascade development, ecosystem hydropower service value shows significant spatial differences, giving rise to a differential rent. Differentiated compensation standards should be formulated on the basis of water and electricity service values. Our assessment results were limited by spatial–temporal scale. Maximization of hydroelectric power benefit relies on the meeting of the requirement of flow extracted by hydropower plants, then an accurate assessment on hydropower service needs daily runoff simulation. This requires eco-hydrological model coupled ecosystem process and hydrological process. Cascade hydropower stations are mainly distributed in the mountain areas. Due to the effect of topography, precipitation and temperature had prominent spatial heterogeneity. However, socio-economics
Table 3 Water resource fee of the Zagunao River Basin. Type 8
3
Annual water consumption (10 m ) Price (Euro/m3) Total (108 Euro)
Industrial
Domestic
Others Hydropower
12.25 0.008 0.094
1.5 0.005 0.007
5.5 0.006 0.033
156a / 0.995
a The runoff used by hydroelectric power is the sum of flows by all stations, because runoff can be reused, so the quantity of water is higher than the total annual runoff.
Conflict of interest
Acknowledgments This study was sponsored by the Chinese Academic Science 135 project: Impact of Minjiang Hydropower Development on Water Resources Safety and the Western Light Talent Culture Project: Standard of Payment for Ecosystem Service based on GIS. We used the InVEST model developed by The Natural Capital Project supported by Stanford University, WWF (World Wildlife Fund) and TNC (The Nature Conservancy). The authors would hereby like to express their sincere thanks. The authors also appreciate the language editing from Prof. XU ZL and the valuable comments from two anonymous reviewers. References Akpınar A, Kömürcü Mİ, Kankal M. Development of hydropower energy in Turkey: the case of Çoruh river basin. Renew Sust Energ Rev 2011;15:1201–9. Becerra MR, Ponce De León E. Financing the green plan (“plan verde”) in Colombia: challenges and opportunities. Workshop on financing of sustainable forest management, Croydon, UK; 1999. Bernard F, de Groot RS, Campos JJ. Valuation of tropical forest services and mechanisms to finance their conservation and sustainable use: a case study of Tapantí National Park, Costa Rica. For Policy Econ 2009;11:174–83. Blackman A, Woodward RT. User financing in a national payments for environmental services program: Costa Rican hydropower. Ecol Econ 2010;69:1626–38. Boyd J, Wainger L. Measuring ecosystem service benefits: the use of landscape analysis to evaluate environmental trades and compensation. Resources for the future discussion paper; 200302–63. Brauman KA, Daily GC, TKe Duarte, Mooney HA. The nature and value of ecosystem services: an overview highlighting hydrologic services. Annu Rev Environ Resour 2007;32:67–98. Brause S. Investigating the creation of a pilot payment for watershed services scheme in Chiapas. Mexico: Colorado State University; 2012. Brinkman W. Innovative financing mechanisms for conservation and sustainable forest management. European Tropical Forest Research. Network; 2001. Budyko MI. Climate and life. New York: Academic Press; 1974. Bureau. FPP. Report on small hydropower production runs cost–benefit investigation. http://www.fjjg.gov.cn/fjwjj/wsjgts/xhhk/webinfo/2008/08/1219391928642948. htm, 2008. [editor]. Butler JR, Wong GY, Metcalfe DJ, Honzák M, Pert PL, Rao N. An analysis of trade-offs between multiple ecosystem services and stakeholders linked to land use and water quality management in the Great Barrier Reef, Australia. Agric Ecosyst Environ 2011. http://dx.doi.org/10.1016/J.AGEE.2011.08.017. Cheng X. Research on ecological compensation theory and application of water and electricity exploitation. Southwest Jiaotong University; 2010. Droogers P, Allen RG. Estimating reference evapotranspiration under inaccurate data conditions. Irrigation and Drainage Systems 2002;16:33–45. Dugan PJ, Barlow C, Agostinho AA, Baran E, Cada GF, Chen D, et al. Fish migration, dams, and loss of ecosystem services in the Mekong basin. Ambio 2010;39:344–8. Dunbar MB, Panagos P, Montanarella L. European perspective of ecosystem services and related policies. Integr Environ Assess Manag 2013;9:231–6. Egoh BN, Reyers B, Rouget M, Richardson DM. Identifying priority areas for ecosystem service management in South African grasslands. J Environ Manage 2011;92: 1642–50. Farley J, Costanza R. Payments for ecosystem services: from local to global. Ecol Econ 2010;69:2060–8. Grumbine RE, Xu J. Mekong hydropower development. Science 2011;332:178–9. Guo Z, Xiao X, Gan Y, Zheng Y. Ecosystem functions, services and their values—a case study in Xingshan County of China. Ecol Econ 2001;38:141–54. Hermann A, Kuttner M, Hainz-Renetzeder C, Konkoly-Gyuró É, Tirászi Á, Brandenburg C. Assessment framework for landscape services in European cultural landscapes: an Austrian Hungarian case study. Ecol Indic 2013. http://dx.doi.org/10.1016/j.ecolind.2013.01.019. Huang H, Yan Z. Present situation and future prospect of hydropower in China. Renew Sust Energ Rev 2009;13:1652–6.
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