河龙区间水土保持措施减水减沙效益分析

Analysis of Water Conservation and Sediment Reduction Effects by Water and Soil Conservation Treatments in the Area of Hekouzhen to Longmen

河龙区间水土保持措施减水减沙效益分析研究采用了“水文法”和“水保法”两种分析计算方法。“水保法”是分析研究的重点。在分析计算中，采用了１９９６ 年土地变更资料和１９９０ 年土地详查资料，并采用二阶等距抽样调查方法核实河龙区间水保措施保存面积；水保坡面措施减洪减沙效益计算采用“串联法”和“并联法”两种方法平行研究，注重了坡面与沟道、洪水与泥沙的有机联系；在计算淤地坝拦泥量的基础上，将淤地坝分为淤平坝地和正在拦洪时期坝地两部分，分别计算其减洪量，并计算了淤地坝减蚀量；水库、灌溉减水减沙量的计算分为减洪水与减常水、减洪沙与减常沙两部分。此外，还考虑了河龙区间工业、生活用水和人类活动增洪增沙对河流水沙变化的影响，尤其是人类活动增洪增沙计算，绝大多数支流采用的是实际典型调查值，增洪增沙指标比较可靠。“水保法”计算结果表明：７０ 年代河龙区间２１ 条有控支流水利水保措施及人类活动等年均减洪４ ．１７７ ～４ ．２５８ 亿ｍ ３ ，年均减洪沙１ ．７２０～１ ．７７５ 亿ｔ ；８０ 年代年均减洪４ ．１４８ ～４ ．２９２ 亿ｍ ３ ，年均减洪沙１ ．６４４ ～１ ．６４５ 亿ｔ；９０ 年代年均减洪４ ．８０５ ～５ ．３８０ 亿ｍ ３ 。

Both “hydrological method” and “water and soil conservation method” are applied in the paper, while the water and soil conservation method is stressed, to study and analyze the water conservation and sediment reduction effects by water and soil conservation treatments in the area of Hekouzhen to Longmen. The data of land re distributed in 1996 and detailed investigation in 1990 are adopted in the analysis and calculation, the preserved area of water and soil conservation treatments in the region of Hekouzhen to Longmen is checked and verified by using the method of second order equidistant sampling investigation. The conservation effects on slopes are calculated by equally using both methods of “in series” and “in parallel” with focus on the organic relations between slope and gully, flood and sediment. Based on calculated sediment retention volumes in warping dams, two types of warping dams are divided, i.e., warping up dams and flood retention dams, and the flood reduction of both types are calculated separately as well as soil erosion deducted by warping dams. Water retention and sediment reduction by reservoirs and irrigation are calculated in both floods and normal flows respectively. Besides, influences on flow and sediment in rivers from water utilization by industry, daily life and human being activities are also taken into consideration, especially flood and sediment increase by human activities for which the data of field typical investigation is accepted in almost all branches. The calculation results by using “water and soil conservation method” demonstrate that the yearly average flood reduction by hydraulic projects, water and soil conservation treatments as well as human activities is 417.7 to 425.8 million m 3, sediment reduction in flood 172.0 to 177.5 million tons in 1970s; flood reduction 429.2 to 414.8 million m 3 and sediment reduction in flood 164.4 to 164.5 million tons in 1980s; and flood reduction 480.5 to 538.0 million m 3 and sediment reduction in flood 200.0 to 220.3 million tons in 1990s.