黄土高原水土保持措施强化降雨入渗分析及灰色预测

黄土高原水土流失综合治理是以强化降雨入渗,减少地表径流,阻止土壤侵蚀为目的。因此,治理区降雨入渗量的大小是衡量水土流失治理效果的关键指标之一。目前入渗量的计算多利用年总降雨量,由于在黄土地区小雨量或小强度的降雨具有与水土流失治理的零相关性,因而会导致对水土流失综合治理强化入渗作用估计的较大误差。提出用1a中产生径流的次降雨总量(产流降雨总量)计算入渗量。以西川河流域为例,采用1997—2001年的降雨径流资料,分别用年降雨总量与产流降雨总量推求降雨入渗系数,对比分析了入渗量随流域水土流失治理度的变化,结果表明:利用产流降雨总量能比较清晰地反映流域治理程度对降雨入渗的影响。在此基础上,采用GM(1,1)灰色动态模型预测西川河流域降雨入渗量随水土流失治理度的变化趋势。结果表明,GM(1,1)灰色模型能够合理地预测黄土高原水土保持措施对自然流域入渗量影响的变化趋势。

Analyses and Prediction on Soil and Water Conservation Measure's Intensifying Infiltration in the Loess Plateau of China

Soil and water conservation measures(SWCM) of the Loess Plateau could control soil erosion by intensifying the infiltration and weakening the runoff. Therefore, the infiltration quantity is one of the important indexes that scale the effect of the soil and water conservation. The infiltration quantity was often calculated by the annual rainfall which products runoff. However, the little quantity rain or low intensity rain in the year has nothing to do with the conservation in the Loess Plateau. It could lead to the estimation error about the change of infiltration with SWCM. The infiltration variating with the catchment SWCM level incensement is studied based on the data of rainfall and runoff of the Xichuan catchment during 1997 to 2001. A gray dynamic model is put forward to the infiltration quantity tendency in the Xichuan catchment was predicted by a gray dynamic model, GM(1,1). The result indicates that the annual rainfall which can product runoff shows the effect of SWCM on infiltration more clearly than the total annual rainfall. The gray (dynamic) model can be used to predicat the tendency of infiltration.