三川河流域重点治理减沙效益分析

三川河流域自1983年列入全国八大重点治理区后,至1992年底止,10年新增治理面积1129km~2,流域累计治理程度达到57.6％。采用水文法与水保法分析该流域重点治理以来的减沙效益,前者的分析结果是,重点治理期间的年均输沙量较重点治理前减少59.03％,每毫米汛期降雨所产生的输沙量分别比1957～1972年、1957～1982年减少61.30％和52.23％;后者的分析结果是年均输沙量分别比1957～1972年、1957～1982年减少44.26％和55.18％。考虑到降雨变化对水文法分析产沙的影响,故10年重点治理期间较重点治理前多年平均输沙量年均减少约为50.0％。

Analysis of the Benefits of Sediment Reduction in the key Harnessment of the Sanchuanhe River Basin

Doting the 10 years, from 1983 to toe end of 1992, the newly increased harnessed area was 1129 km~2, the accumulative degree of harnessment of the river basin reached 57. 6%, Methods of hydrology and of soil conservation were used separately to analyze the benefits of sediment reduction gained since the introduction of key harnessment. The result reached by the method of hydrology indicates that during the period of key harnessment the average annual sediment load had reduced by 59. 03% compared with that before the key harnessment, sediment load generated by, per mm rainfall during flood season reduced by 61.30% and 52. 23% respectively compared with that in the 1957~1972 and 1957~1982 perio;the result drawn by method of soil conservation shows that the average annual sediment load reduced by 44. 26% and 55. 18% respectively compared with that in the 1957~1982 and 1957~1982 periods. Taking into consideration of the effect of variation of rainfall on the sediment load as estimated by the method of hydrology, during the 10 years of key harnessment, the avervge annual sediment load was about 50. 0% less than that before the key harnessment.