Experimental Investigation On Rules Of Rainfall Runoff On Sloping Land In Red Soil Hilly Region

Water and heat resources are abundant in red soil hilly region, which offers manyadvantages for plant growth. However, the section rainfall distributing odds, rain and heatnot at the same period, red soil holding water ability firmness, otherwise, the sectionsloping field exploiture person and soil inconsistency increasingly intensify atout-of-order predicament, the reasons lead to water and soil loss increasing, seasonaldrought, land degradation, flood and waterlog disasters had great influence on localagriculture continuable development and eco-environment improvement.This study rainfall-runoff with different lands use modes (Oiltea Camellia field andResumed field, projections area 5m×20m) at Taoyuan agriculture ecologcal experimentstation of CAS in red soil hilly region. Rainfall was observed with pluviometer, Usingthin triangle-weir and water line meter observed runoff and using flow meter and HOBOautomatic observed flux and velocity of flow. This text bases on soil characterdistribution on sloping land, analyze with different land use modes runoff and interflowoccur rules and effect factors, interflow occur causation. The main results showed asfollows:(1) Soil particle sizes content happen jump at 40cm depth in soil profile. And thepower content decrease and sand content increase along with depths. The content oforganic matter increaseing range become slowly at 40cm depth and that has moderatevariability in soil profile. And soil bulk density has weak variability in soil profile. Thesaturated hydraulic conductivity (K₁₀) increases rapidly from surface to depth. K₁₀ is40～110cm.d^-1 belongs to rather big level at 20～110cm depths and that increases alongwith depths. Runoff is subdivided into: surface (0cm), uplower (0～40cm) anddownlower (40～110cm) according as soil properties distribution in soil profile.(2) Runoff flux more than interflow at the same rainfall. The coefficient of runoff are1.5% and 9.0% in Oiltea Camellia field and Resumed field. And the coefficient ofinterflow are 1.2% and 0.7% in Oiltea Camellia field and Resumed field, laggard durationand prolonged duration usually are 3～6h and 6～18h and that have little difference inOiltea Camellia field and Resumed field.(3) Rainfall-runoff processes have difference with different land use modes, rainfall,rain duration, maximal rain intensity, initial soil water contents, hereinto, rain durationand maximal rain intensity are the most factors. The response runoff peak flux to rainintensity is the most visible. In kinds of influence interflow processes factors, first, rainfall, next, land use modes, last, runoff. Rain duration and initial soil water contentsinfluence interflow processes are most obvious. Runoff effect on interflow in OilteaCamellia field less than that in Resumed field. Thereinto runoff influence interflowprocesses is most obvious in rainfall factors. With alike initial soil water contents andrainfall, runoff flux and runoff rate, peak flux and runoff duration in Oiltea Camellia fieldare less than in Resumed field, but average infiltration rate more than the latter. Differentland use modes have most influence on rainfall-runoff processes with little rainfall. Whenrainfall greatly and happening rainfall-runoff processes, maximal rain intensity is themostly factor on influencing runoff flux and runoff rate, peak flux and runoff time, next,rainfall. Infiltration rate influenced factors have rain duration firstly, rainfall secondly.(4) Interflow flux is effected greatly initial soil water contents, rain duration,maximal rain intensity, average infiltration rate. Interflow processes duration affectedprimary factors are rain duration, initial soil water contents, infiltration rate. Soil depth isprimary factor on influencing laggard duration, and others influence inconspicuous. Soildepth, initial soil water contents, average infiltration rate are the mostly factorsinfluencing prolonged duration.(5) Correlations analysis of interflow factors results show: the same layerscorrelations are in no evidence. Correlations of peak flux and other interflow factors, butlaggard duration, are positive linear. Interflow duration correlate with peak flux closely,prolonged duration being positive best linear correlations. Laggard duration and otherinterflow factors have negative linear correlations. Prolonged duration correlate withinterflow duration and peak flux being positive best or better linear correlations. Positivebetter linear correlations exist among every one of interflow factors. Down-layersinterflow flux and peak flux exist positive best linear correlations with correspondingup-layers factors.