基于SCS-CN模型的黄土高原丘陵区坡地微型集雨垄垄面径流量预测

为了探寻我国黄土高原丘陵区坡地垄沟集雨种植控制水土流失和增产机理,本研究利用试验期2019年坡地微型集雨垄收集的19次降雨-径流资料,率定不同坡度(0°、5°和10°)微型集雨垄SCS-CN模型的径流曲线数CN值和初损系数λ值,利用5次降雨-径流资料检验模型的有效性。结果表明:自然降雨条件下,坡地微型集雨垄径流量随坡度增大而增大,λ值随坡度增加而降低,CN值随坡度变化不明显;William坡度修正公式、Huang坡度修正公式和Huang优化坡度修正公式确定纳什效率平均值分别为0.83、0.96和0.98,平均相对误差分别为17.67%、8.51%和5.84%;Huang优化坡度修正公式考虑坡度因子,率定径流曲线CN和初损系数λ,模拟精度优于Huang坡度修正公式和William坡度修正公式,适合于我国黄土高原丘陵区坡地微型集雨垄径流预测,为坡地垄沟集雨种植控制水土流失和增产提供科学依据。

Ridge surface runoff estimation for micro-rainwater-harvesting-ridges on slopping land in the hilly areas of the Loess Plateau based on SCS-CN model

To explore the mechanism underlying soil erosion control and crop yield increase in ridge-furrow rainwater harvesting production on sloping land in the hilly areas of the Loess Plateau,China,we modified Soil Conservation Service Curve Number(SCS-CN) model to estimate the runoff for different slopes(0°,5°,and 10°) of micro-rainwater-harvesting-ridges.The curve number(CN) and the initial abstraction coefficient(λ) in the SCS-CN model were calibrated according to 19 rainfall-runoff events of micro-rainwater-harvesting-ridges on slopping land during April 1 to October 20 in 2019.The applicability of the SCS-CN model was evaluated using five rainfall-runoff events of micro-rainwater-harvesting-ridges on sloping land.The results showed that runoff increased and λ decreased with increasing slope.Effects of slope gradient on the parameters of CN were not obvious under natural rainfall conditions.The mean Nash-Sutcliffe efficiency was 0.83,0.96,and 0.98 for the William Slope Correction Formula,Huang Slope Correction Formula,and optimized Huang Slope Correction Formula,while the mean relative error was 17.67%,8.51%,and 5.84%,respectively.The optimized Huang approach calibrated the curve number(CN) and λ by considering slope gradient factor.Therefore,the simulation accuracy of the SCS-CN model for the optimized Huang approach was significantly higher than that for the approaches of William and Huang.The performance of the SCS-CN model modified by the optimized Huang approach was acceptable for runoff estimation of micro-rainwater-harvesting ridges.Our results provide valuable information on soil erosion control and grain yield increase in the hilly areas of the Loess Plateau.