减轻二滩水库泥沙淤积的生态系统服务价值评估

Ecosystem service valuation of Ertan Reservoir watershed in mitigating reservoir sand sedimentation

基于ArcGIS9.2,构建了生态系统减轻水库泥沙淤积的评估模型,并结合泥沙输移比(SDR)和通用水土流失方程(USLE),模拟了二滩水库集水区的产沙量和保沙量及其空间分布特征以及水库使用年限内其生态系统服务价值.结果表明:2000年,二滩水库集水区土壤保持量12.1×108t.a-1,土壤保持量高值区主要分布于雅砻江干流和支流水网附近;泥沙输移比的高值主要分布在河道附近和水库周边,水库周边是最主要的产沙区和保沙区;研究区实际产沙量为629.3×104t.a-1,占实际土壤侵蚀量的12.7%;农田是研究区最主要的产沙源,其产沙量占集水区总产沙量的62.9%;林地平均单位面积的保沙价值最高.在二滩水库使用年限内(100a),集水区对于减轻二滩水库泥沙淤积的总价值为27.53亿元.

By using software ArcGIS 9.2, an evaluation model was established to simulate the ecosystem service of Ertan Reservoir watershed in mitigating the sand sedimentation in the reservoir. In the meantime, sediment delivery ratio and universal soil loss equation were used to simulate the spatial patterns of the annual sediment yield and sediment retention in the watershed as well as the value during the service life period. In 2000, the total quantity of soil retention in the watershed was 12. 1×10^8 t·a^-1. The region with higher soil retention was near the main and branch streams of Yalong River, and that with higher sediment delivery ratio was near the streams and the Ertan Reservoir. The region with higher sediment yield and sediment retention was around the reservoir. The actual sediment yield in the study area was 629.3×10^4 t· a^-1, occupying 12. 7% of the actual soil erosion volume. Farmland was the most important source of sediment yield, with its sediment yield occupying 62. 9% of the total. The contribution of forestland to the mitigation of reservoir sand sedi-mentation was higher than that of the other lands on a per unit area basis. For the reservoir＇ s de-signed operating life （ 100 a）, the total value of the watershed in the service of mitigating Ertan Reservoir sand sedimentation was 2.75 billion yuan.