洞庭湖流域未控区间水量平衡分析

Water Balance Analysis in the Uncontrolled Area of Dongting Lake Basin

摘要: 洞庭湖是长江流域重要的调蓄湖泊，由于三口四水以下区域未设控制测站，该部分面积降雨形成的径流量无法直接观测，定量研究较少。针对该问题，本研究分别建立了SWAT模型和新安江模型，选取了不同的目标函数，模拟1991~2009年的区间径流，以反推的区间径流年总量值进行验证。结果表明：1) 在SWAT模型方案中，目标函数同时纳入确定性系数和总量相对误差所得的区间径流模拟精度最高；2) 在新安江模型方案中，在以残差平方和为目标函数的基础上，引入区间径流为正值的约束，模拟效果最好；3) 基于洞庭湖区间的径流系数以及水文模型的模拟结果，发现1995年和1996年前后，该流域的降雨径流关系可能发生了变化，因此采用分段率定的方式，在率定期和检验期均可获得具有较高精度的模拟结果，两个模型的水量平衡问题得到了很大的改进。提出的模型和方法可为洞庭湖流域未控区间水量平衡分析提供依据。

Abstract: Dongting Lake possesses an important regulation capability in the Yangtze River basin. Because there are no flow-gauged stations in the area below the three inlets and four tributaries, the intervening runoff derived from precipitation cannot be observed directly. The quantitative related analysis is still scarce. To address this issue, the SWAT and Xin’anjiang models are established with various objective functions, respectively, to simulate the runoff from 1991 to 2009, which is verified by the annual total intervening runoff calculated by the water balance equation. The results show that: 1) The deterministic coefficient (DC) incorporated with the total relative errors (RE) provides better performance in the SWAT model; 2) A positive intervening runoff constraint considered with the sum of squares for residuals can improve the simulation accuracy for the Xin’anjiang model; and 3) It can be inferred that the relationship between rainfall and runoff may change around 1995 and 1996, based on runoff coefficients during 1991 to 2009 and simulated results of the hydrological models. Therefore, split-sample calibration is used and produces more accurate simulation during calibration and validation periods for both SWAT and Xin’anjiang models. The proposed method can relieve the water balance problem and provide a basis for water balance analysis in uncontrolled areas of Dongting Lake basin.