Study On Theory And Applicability Of Soil And Water Conservation On Level Ditch Cultivation

Purple soil sloping farmland is precious agricultural resource in Sichuan provice of south China. Sloping farmland is of the total farmland of 83.07%. It was being the main problem of the soil and water erosion. So it is very important to strengthen the effects of soil and water conservation. Rain simulations have been conducted on fields study on effects of soil and water conservation about level ditch cultivation in sloping farmland. The effects on the ridge's stability and applicability of rainfall strength, slope gradient, have been discussed, and then had anlysed and simulated with the modules of SLOPE/W and SEEP/W of GEO-SLOPE software. The following is include:(1) Comparing to the soil and water conservation of different cultivations to analyse the effects on rainfall strength,slope gradient,rainfall time.The result is the level ditch cultivation is the best, especially under the strength of 72.02mm/h.(2) The conclusions were as the following: During 0°～20°,rainfall strength is lower 72.02mm/h,then the cross ridge have a good stability and safety conductivity. 25°slope isn't suit to this palce.(3) Analysis on changes with infiltration on the level ditch have been done.Considiering when the upper layer of infield have the best reserves of water, when have worst, and which slope gradient is the critical slope. There are conclusions as following: When rainfall strength is 72.02mm/h, the best slope is 10on effect of soil and water conservation,when it is 53.95mm/h, the best slope is 15°.20°is the critical slope on soil and water conservation in this place.(4) Combining the the modules of SLOPE/W and SEEP/W of GEO-SLOPE software to analyzing process of cross ridge stability, compute the stability coefficient of ridge in order to find out the range of the level ditch cultivation applicable, the following is include.during 0°～20°gradient,the cultivation is suit for this place.25°gradient slope is the worst slope in this place,so suggest to do not ues this cultivation.20°gradient is the critical slope.