数字流域模型在长江上游龙河流域的应用

Application of digital river basin model to Long River basin of upper Yangtze

数字流域模型是当前水文领域研究的热点问题。本研究选取长江上游龙河小流域为研究对象,将数字流域模型应用于长江流域。首先利用Arc GIS软件提取河网信息,选取该流域1982年汛期的降雨及流量过程,采用基于因素分析的图解法对模型进行率定及验证。结果显示模拟的Nash系数达到0.965,洪峰相对误差在10%以内,表明该模型可以很好地模拟长江小流域产汇流过程。然后还对模型中涉及的几个重要参数进行敏感性分析,结果表明:土壤垂向饱和导水率主要影响峰值,二者成负相关;土壤初始含水量主要影响径流量,二者成正相关;田间持水量与峰值和径流量均成负相关;植被截留水量与峰值和径流量均成负相关;糙率主要影响峰型,与峰值成负相关。若要将率定后的数字流域模型应用到具体工程实践中,还需用近期实测数据对模型进一步进行验证。

Distributed hydrological modeling is a hot issue in current hydrological research.This study applies a digital watershed model to a small watershed of the upper Yangtze.First,the ArcGIS code is used to extract river network information.We select the rainfall and flood series of the river basin of 1982,and calibrate and verify the model parameters using a graphical method based on factor analysis.The calibration gives a Nash efficiency coefficient of 0.97 and peak errors within 10%,indicating that the model can well simulate the runoff yield and flow concentration in this small watershed.Then,a sensitivity analysis is made on several key parameters involved in the model.The results show that vertical saturated hydraulic conductivity affects the flood peak only and the two parameters are negatively correlated.The initial water content of soil affects the runoff only,with a positive correlation;field capacity is negatively correlated with the flood peak and runoff process;vegetation water interception is negatively correlated with the flood peak and runoff;and roughness,negatively correlated with the peak value,affects the shape of flood peak only.We suggest that further validation with recent measurements be needed before the model is applied to the engineering problems in the study area.