概化的Tank模型及其在龙羊峡水库汛期旬平均入库流量预报中的应用

Predigested Tank Model and Its Application in 10 days Averaged Inflow Forecast of the Longyangxia Reservoir during Raining Seasons

Tank模型 (又称为水箱模型 ) ,是一种用于流域径流预报的确定性水文模型 .根据龙羊峡水库入库主要产流区———黄河上游唐乃亥水文站以上流域下垫面条件与产汇流特性 ,将其概化为以降雨量为输入、径流量为输出的单孔出流的线性水箱 .并用于该水库汛期旬平均入库流量的预报 .经对历史资料进行拟合和试验预报的结果表明 ,该模型具有较高的预报精度 ,现已应用于黄河上游龙羊峡水库汛期旬平均入库来水量的中期预报中 。

The Longyangxia Reservoir is the biggest reservoir in the upper reaches of the Yellow River. It is located the eastern Tibetan Plateau. After the reservoir being completed a long-period drought occurs in the Tibetan Plateau. Less inflow comes into the reservoir. According to the flood control program, however, it is necessary to drain much water in the flood season for the reservoir security. In one aspect, managers must assure enough water after flood season to produce electricity. And in another aspect, they must assure the reservoir security. As the future rainfall and water income is unknown, the reservoir should not store much water in the flood control stage. Therefore a very high accuracy of long-and-middle inflow forecast is urgent. Tank model is a certainty mathematics model, which is used to forecast runoff in a basin. In this model only consider the input and output process, ignoring the physical process of basin water transformation. So for a very large basin with a complicated hydrologic and climate situation, this model can be well applied for flood control. The Tangnag Gauging Station is located in the upper reaches of the Yellow River, gauging the main inflow to the Longyangxia Reservoir. According to the underlying surface condition and runoff yield characteristics of the working basin, three independent runoff yield areas can be divided from the working basin. Each runoff yield area is predigested to be a single opening linear water tank, of which the input is precipitation and the output is runoff. According to the water balance theory in flood period a model of calculating the runoff in flood period is worked out. Combining the three runoff yield areas, the runoff averaged over a flood period can be yielded. Thus, a medium-term runoff forecast model was put forward. Optimum seeking method is applied, and forecast parameter is determined by regression analysis. This model can be used to predict the mean inflow to the Longyangxia Reservoir for a period of ten days. Through fitting history data and testing the forecast it is found that the model is of a satisfying precision. The model calibration accuracy reaches to 95% or more. An actual forecast applied in July^September 1999 showed that in this model the maximum prediction error was 15 2%, and the minimum one was 3.7%. The error is lower than the allowance, 20%, of the Standard 《Hydrologic Information Forecast Code》.