Numerical Estimation of Water Balance in a River Basin

A multiple regression analysis, one of the statistical numerical estimation methods of water balance in a basin, is introduced with an example basin in this paper. This method can be used easily by means of a digital computer. The mathematical bases of the method are given here. As for the runoff model by this method, the whole basin consists of two kinds of areas. One is a non-irrigated area, the other is an irrigated area. An example of an estimation of water balance of multiple regressional models is given for the Yashiro river basin in Fukushima prefecture. The prominent character of this method is that the models simulate very well the low flow and the return flow of the river at the checking points. Some results of the simulation are shown in several figures. From these results, this method simulates totally water balance well.