修正水沙资料系列初探

Revised Data Series of Water and Sediment

摘要: 河口镇至龙门是黄河产沙最多的河段，经过多年水土保持治理，进入黄河的泥沙已显著减少，流域下垫面的生态修复，使早期观测的水沙资料不再具有可重现的性质，必须修正。修正水沙资料的实质是交换下垫面，用预测期的下垫面替换观测期的下垫面，其分析计算需要大量资料，非常复杂。降水量是产生水沙径流的基本因素，降水强度和降水地区对产沙的多少有重要影响。径流系数是降水量中产生径流量的百分数，产沙系数是降水中与地面接触水体的动能，冲动并带走的泥沙量与降水量的比值。不同的下垫面对降水的储存、下渗、消能和抗冲有不同的响应，直接在径流系数和产沙系数的变化上反映出来。把近期和早期各时段径流系数、产沙系数的比值，作为对早期各时段水沙量的修正系数，再考虑各时段暴雨和降水地区差异的影响。用此方法修正了河口镇至龙门早期8个大沙年的水沙量。对于预测未来的水沙条件，可以肯定，用本次修正的成果比直接用早期观测的水沙资料会更接近实际。

Abstract: Hekouzhen-Longmen reach is the basin of the most soil erosion in the Yellow River. As water and soil conservation works have been implemented for many years, consequential quantities of sediment into the Yellow River have remarkably reduced. River basin’s underlying surface has been definitely ecologically restored, so that data series of water and sediment measured early cannot return again and must be revised. The substance of revising data series of water and sediment is to exchange underlying surface, by taking underlying surface of predicted time to alternate that of measured time, so that analysis calculation needs many data and is extraordinarily complex. Rainfall amount is a basic factor for soil and water loss. Rainfall intensity and rainfall area have important effects on the quantities of runoff and sediment discharge. Runoff coefficient is the percentage of runoff amount over rainfall amount belonging to water body conversion. Soil loss coefficient is the ratio of sanding amount to rainfall amount, and sanding amount is eroded and carried by kinetic energy of water body of contact ground in rainfall belonging to energy conversion. Different underlying surfaces have different responses in poundage, infiltration, energy to consume and scour resistance of rainfall, which directly reflect in changes of runoff coefficient and soil loss coefficient. The ratio of runoff coefficient to soil loss coefficient in various times of recent stage and early stage is taken as the correction factor for water and sediment amount in various times of early stage. Again the influence of regional difference of rainstorm and rainfall in various times is considered. This method has been used to revise the quantities of water and sediment in eight years of much sediment in early stage on He-Long reach. The revised data series of water and sediment is more accurate than the data series measured early for predicting future water and sediment quantities.