| The yinshan Northern grassland with climate change and human activities is not reasonable use, under the action of ecological degradation serious. This study USES the field observation and the method of combining indoor experiment research the Alps mountain desert grassland water cycle mechanism and soil erosion etc, problems existing in water for management of degraded grassland and implementation of grassland supervision and management with water reasonable use basis.The main content of this study are:the component part of:water of rainfall infiltration characteristics, soil moisture changes of time, evapotranspiration time changes and surface runoff generation mechanism and sediment relations, based on the simple slope surface water cycle model.The main research results:(1) Yinshan Mountain desert grassland soil surface Infiltration rate in ground 0.7235mm/min; Infiltration coefficient of 0.22995; unsaturated soil hydraulic conductivity for the 3.6535cm/s (219.21cm/min).(2) Soil moisture in vertical distribution, deep in the soil layer 60cm surface to the soil moisture with "S" type distribution; 30cm from surface to depth, evaporation by rainfall and the comprehensive influence factors such as soil water depths of 40cm gradually reduce soil moisture content, appeared second peak, soil moisture content from 60cm 40cm to gradually decline.30cm than 60cm depth of soil water content to the surface to deep 30cm soil moisture content is stable.(3) In Time distribution of soil moisture, soil moisture from 2007 to 2009, stability of soil moisture decreased year by year. In the month average monthly change, the monthly average soil moisture value is not the peak concentration of 7,8 and 9 in the month of rainfall, but in April or October. The diurnal variation of soil moisture are driving factors of rainfall; rainfall,10cm and 30cm depth of soil water content increased; No rainfall conditions, the influence of by evaporation, soil moisture continues to decline.(4) For the observed values established on the basis of simple soil water consumption model. Through calculation model for the largest, from the soil humidity value to plants in coefficient wilting 10cm and 30cm depth 16 days and 19 days respectively need.(5) Non-saturated soil to produce rainfall kinetic energy limit runoff in 150-190J/(m2·cm) between. Kinetic energy of rainfall to produce runoff and rainfall usually in the 110J/m2 product above or below this value of rainfall intensity of rainfall is too weak, or too small cannot produce the rainfall runoff; higher than this value did not result in rainfall runoff Rainfall duration is usually very long time, the strongest moment of rainfall intensity in the 1cm·h-1 below the soil infiltration rate below. Rainfall generated runoff erosivity (R value) minimum is 97, the other was more than 145, the observed maximum is 574. (6) And rainfall process synchronous monitoring soil moisture changes occurred in view of the status of runoff, when 5cm～10cm depth of soil moisture no change or change the basic research area that was modest, for super permeability ground runoff.(7) Initial stage in runoff sediment content within, after falling rapidly in 1g/L stable below level. Runoff sediment content up to start of 6,～7 g/l (sometimes even reach 20.2 g/1). Runoff product mainly powder primarily. Mainly of grains powder 80%, very fine sand content 7%, viscous grain 13%.(8) In the study area to the ground rainfall redistribution of process, most through soil water infiltration become. Again through soil physical evaporation and transpiration of plants, from the soil circle into the atmosphere. A very small part of rainfall runoff, flows into rivers and streams.
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