论文部分内容阅读
山坡是流域水文响应的基本单元,对山坡降雨产流关系特别是山坡降雨产流的阈值现象的研究,有助于增进山坡水文过程的了解,进而改进流域的降雨径流模拟。本研究利用经过野外实验详细验证的二维山坡水动力学数值模型THRM,借鉴统计物理的思路,将土壤水分运动由微观网格升尺度到宏观山坡。通过数值试验分析山坡尺度降雨径流关系的特征,结果显示:山坡尺度降雨径流响应普遍存在阈值-线性的两阶段规律,即降雨低于某阈值时不产流,大于该阈值后降雨量与产流量呈现线性关系。数值试验还揭示了降雨阈值出现的过程机理,即降水入渗至土壤-基岩界面,填满基岩地形的凹陷后,交界面土壤水分达到近似饱和状态,山坡达到蓄满状态,土壤基岩交界面成为水流的优先通道而开始产流。山坡产流的降雨阈值可以认为是使山坡蓄量空间充满的降雨量。定义山坡蓄满后降雨量与产流量的相关系数为山坡产流系数,研究表明降雨阈值随着坡度的增加而减少,而山坡产流系数随着坡度的增加而增大。
Hillside is the basic unit of hydrological response in the basin. The research on the relationship between rainfall and runoff on the hillside, especially the threshold phenomenon of rainfall and runoff on the hillside contributes to the understanding of hillside hydrological process and further improves the rainfall runoff simulation. In this study, a two-dimensional sloped hydrodynamic numerical model THRM, validated in detail in field experiments, is used to draw the idea of statistical physics to elevate soil moisture movement from a micro grid to a macro-slope. Through numerical experiment, the characteristics of rainfall-runoff relationship on hillside scale were analyzed. The results showed that the threshold-linear two-stage law of rainfall-runoff response generally existed on hillside, ie no rainfall was produced when the rainfall was lower than a certain threshold, and the rainfall and runoff Present a linear relationship. The numerical experiment also revealed the process of rainfall threshold, that is, after rainfall infiltrated into the soil-bedrock interface and filled the depression of the bedrock topography, the soil moisture at the interface reached an approximate saturation state, the hillside reached a full state, The interface becomes the priority channel of the flow and begins to flow. The rainfall threshold of hillside runoff can be regarded as the rainfall which makes the hillside storage space full. The correlation coefficient between rainfall and runoff volume after hillside storage is defined as the runoff production coefficient. The research shows that the rainfall threshold decreases with the increase of slope, while the runoff production coefficient increases with the slope.