延河流域 1997—2006 年林草植被减洪减沙效应分析简

根据延河流域长系列水文资料,对1997-2006年林草植被减洪减沙效应进行重点分析.结果表明：1）与基准期的1956-1969年相比,延河流域1997-2006年汛期降水、径流、输沙量分别减少了15.1％、45.6％和67.2％.截至2006年底,延河流域（含未控区）水土保持措施保存面积37万1 751 hm2,其中林草措施保存面积30万7 412hm2,占82.7％;2）延河流域1997-2006年林草植被年均减少洪水量2 885万m 3,年均减沙量1 695万t,分别占水土保持措施年均减洪减沙总量的63.6％和58.2％,其中林地减洪减沙效应最为明显,其减洪减沙量分别是草地和封禁治理措施减洪减沙量之和的4.9和4.7倍;3）1997-2006年延河流域林草植被减洪减沙上升趋势明显,林草植被与工程措施减洪量之比约为64％∶36％,减沙量之比约为58％∶42％.

Effect of forest-grass vegetation on reducing flood and sediment from 1997 to 2006 in Yanhe basin

The effect of forest-grass vegetation on reducing flood and sediment from 1997 to 2006 was studied based the long-term hydrologic data of Yanhe basin.The results were as follows：1） Compared to the baseline period from 1956 to 1969,the precipitation,runoff and sediment discharge decreased by 15.1％,45.6％ and 67.2％ respectively from 1997 to 2006.Up to 2006,the total saved area with soil and water conservation measures in Yanhe basin （including uncontrolled area） summed up to 371 751 hm2,in which the total saved area with forest-grass planting measures was 307 412 hm2,accounting for 82.7％.2） The annual average flood and sediment were reduced by 28 850 000 m3 and 16 950 000 t respectively by forest-grass vegetation,which accounted for 63.6％ and 58.2％ of the annual average amount of reduced flood and sediment caused by soil and water conservation measures.Among the measures,the effect of forest land on reducing flood and sediment was the most obvious,whose annual average amounts of reduced flood and sediment were 4.9 and 4.7 times that of the sum of grassland and blockading administration measures.3） The upward trend of the effect of forest-grass vegetation on reducing flood and sediment from 1997 to 2006 was obvious,which had became the major part of the soil and water conservation measures to reduce flood and sediment.The ratio of the amount of reduce flood by forest-grass vegetation to engineering measures was 64％ ∶ 36％ and that of reduced sediment was 58％ ∶ 42％.