山地小流域に関する陸水学的研究(III) 谷頭部に形成される地下水の特性

Abstract

The base flow from Takigatani experimental basin in the Tanakami mountain range, Shigaprefecture, occurs mainly from the local unconfined aquifers at the heads of the two first-order val-leys. The investigation of the aquifers and the continuous observation of the groundwater levelwere carried Out to elucidate the characteristics of the water balance of the aquifers. The threemathematical models, the nonsteady linear model, the quasi-steady nonlinear model and thenumerseal model, were used at the processing of the observational data. The time variation and thequantity of the groundwater recharge were correctly estimated through the nonsteady linearmodel and quasi-steady nonlinear model, respectively.It was found that the aquifer of A-valley transforms the surface runoff from the mountainslopes to somewhat similar to the subsurface runofl and that it does not eventually modify thesubsurface runoff and the base flow from the mountain slopes. It was also found that the charac-teristics of the sediment production from this basin can be explained by the sediment balance atthe sand deposits associated with the water balance at the heads of the first-order valleys.