A STUDY ON HYDROLOGICAL PROCESS OF SPRING WATER PONDS ON MUSASHINO UPLAND TOWARDS WATERSIDE RESTORATION

Abstract

 In order to restore the spring water ponds on the Musashino Upland, which are valuable waterfront areas of the urbanized area, it is necessary to elucidate the hydrological process. This study performed a hydrological analysis using a simple structure consisting of storage tanks which was proposed in the 1980s for Sanpoji Pond in Shakujii Park to an eight-month analysis from January 1 to August 31, 2023. The main points newly taken into consideration in the model are that the amount of groundwater pumped is added to the amount of pond runoff, and the amount of loss due to outflow outside the groundwater recharge area is taken into account. As a result, the Nash-Sutcliffe efficiency of daily pond runoff exceeded 0.7, and the hydrological model showed good reproducibility. Furthermore, based on the correspondence between measured values of groundwater level and analytical values of groundwater storage, we showed that the effective porosity of the aquifer may change in response to heavy rain. From the above, we were able to present an example of the hydrological characteristics of a spring pond on the Musashino Plateau where spring water has dried up.