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| Evaluation of a watershed ecosystem service for avoiding reservoir sedimentation and its economic value based on pattern and process—a case study from Ertan reservoir in Yalong river |
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Abstract The pattern and processes of ecosystem is basis of ecosystem services’ supply. A model was established to simulate an ecosystem service of avoiding reservoir from sedimentation and its economic value based on the process of sediment delivery in a watershed. The model included fabricating the watershed of the study reservoir. The sediment retention coefficient of different land cover types were used to simulate the spatial patterns of the annual quantity of the sediment that were prevented from entering the reservoir by the vegetation in each cell followed the flow path in watershed. The economic value of the ecosystem service in this model was determined by the marginal cost of reservoir desilting. This study took the Ertan reservoir as an example. The results showed that the pattern of land cover change was mainly performanced in grassland transforming to forestland in the upper and forestland transforming to farmland and grassland in lower Yalong River from 2000 to 2005. The total actual soil erosion was little changed in the five years. However, the total sediment yield to Ertan reservoir had the large scale increase in 2005. Farmland was the most important source in sediment yield. Most eroded soil was intercepted by different types of ecosystems in the process of sediment delivery in a watershed. The region with a higher quantity of sediment retention was around the reservoir. The absolute quantity of average sediment retention in forestland was lower, so the sediment retention ability of forestland failed to be brought into fullest play in watershed. The total value of the avoided Ertan reservoir sedimentation service in the watershed was 44.2 and 78.6 billion Yuan in the 2000 and 2005.
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Received: 27 January 2011
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