Mechanism of soil and water loss under rainfall and earth surface characteristics in a semiarid loess hilly area
Mechanism of soil and water loss under rainfall and earth surface characteristics in a semiarid loess hilly area
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发表时间：
2006
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通讯作者：
Wei Wei-Wei;Chen Li;Fu Bo
中科院分区：
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作者：
Wei Wei-Wei;Chen Li;Fu Bo
在甘肃定西安家坡小流域（35°35′N，104°39′E）北坡设置15个试验小区，分别设置10°、15 °和20°坡度3个重复，研究了5种土地覆盖类型：农田（Triticum aestivum L.cv Lecuan）、草地（Medicago sativa L.）、草地（Medicago灌木林（沙棘（Hippophea rhamnoides L.），林地（油松卡尔。）和草地（Stipa bungeana Trin.）通过测定地表径流量、侵蚀量和土壤初始含水量，采用偏相关和方差分析方法，研究了降雨特征和地表特征对土壤侵蚀和水土流失的影响。结果表明：降雨量、最大30 min雨强以及二者的乘积与径流量呈极显著正相关，而与侵蚀量呈显著正相关，与土壤初始含水量呈显著负相关，与土壤初始含水量呈显著正相关。降雨量与最大30 min雨强的乘积对土壤侵蚀产流的影响较大，与降雨量、平均雨强等降雨特征的相关性较弱;土地利用类型是加剧或减弱土壤侵蚀产流的最重要因素;坡度在10° ~ 20°范围内对土壤侵蚀产流的贡献不大，但对土壤侵蚀产流的贡献较小。坡度越大，侵蚀速率越大，尤其是在15 ° ~ 20 °之间，一般来说，坡度越大，人为干扰越严重的农田和草地，越容易发生径流和土壤侵蚀。前期土壤含水量在表层（0~ 20 cm）与径流量和土壤侵蚀量的正相关性较其它各层显著。
Soil and water loss in the semiarid loess hilly area is influenced by many factors.In this study,fifteen experimental plots were established and located on the north-facing hill-slopes of Anjiapo catchment(35°35′N,104°39′E) in Dingxi,Gansu province.Three replications(10°,15° and 20° slope degree,separately) with the following five land cover types were investigated: cropland(Triticum aestivum L.cv Leguan),pastureland(Medicago sativa L.),shrubland(Hippophea rhamnoides L.),woodland(Pinus tabulaeformis Carr.) and grassland(Stipa bungeana Trin.).Surface runoff,erosion amount and initial soil water content were measured.Using partial correlation and analysis of variance(ANOVA),soil erosion and water losses influenced by rainfall features and earth surface characteristics were studied.Results showed some important facts as follows.Runoff rate has significantly positive relations with rainfall values, maximum 30min rainfall intensity and the product of these two factors.Erosion rate,however,is highly influenced by the product of rainfall and maximum 30min intensity,and has weak correlation with other rainfall features such as rainfall amount and average intensity.Land use type is the most vital factor which could reinforce or weaken the soil erosion and water loss.Slope steepness ranging 10°to 20°contributes nothing on runoff but erosion,and erosion rate increases obviously with slope steepness,especially from 15 degree to 20 degree.In general,cropland and pastureland with higher slope degree and severe human disturbance are very prone to occurrence of runoff and soil erosion.Furthermore,antecedent soil moisture in the surface layer(0～20cm) has a more significant positive correlation with rates of runoff and soil erosion than that in other layers.