著者

菅原 正巳

出版者

独立行政法人防災科学技術研究所

雑誌

防災科学技術 (ISSN:04541871)

巻号頁・発行日

vol.7, pp.1-5, 1969-02-20

著者

菅原 正巳

出版者

水文・水資源学会

雑誌

水文・水資源学会誌 (ISSN:09151389)

巻号頁・発行日

vol.6, no.3, pp.268-274, 1993-09-10 (Released:2009-10-22)

被引用文献数

2

著者

菅原正巳

出版者

防災科学技術研究所

雑誌

国立防災科学技術センター研究報告

巻号頁・発行日

no.37, 1986-03

著者

菅原 正巳

出版者

水利科学研究所

巻号頁・発行日

no.137, pp.37-53, 1981 (Released:2011-03-05)

著者

菅原 正巳

出版者

水利科学研究所

巻号頁・発行日

no.92, pp.47-59, 1973 (Released:2011-03-05)

著者

菅原 正巳

出版者

Tokyo Geographical Society

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.94, no.4, pp.209-221, 1985-08-25 (Released:2010-12-22)

被引用文献数

3 4

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The tank model is very simple as shown in Fig. 1. We can consider that it corresponds to the zonal structure of groundwater as shown in Fig. 2. In spite of its simple outlook, the behaviour of the tank model is not so simple. Corresponding to various types of input rainfall, it shows various types of response as shown in Fig. 5 by its nonlinear structure caused by the positions of side outlets which are set somewhat higher than the level of the bottom.The tank model shown in Fig. 1 is used to calculate the daily discharge from the daily precipitation for Japanese river basins. For the flood analysis, data of short time unit are necessary and an appropriate time unit is suggested to be given asT.U.=0.05√A, where T.U. is the time unit (hour) and A is the catchment area (km2). Table 1 shows some examples of appropriate time unit for various catchment areas. For the flood analysis the tank model with two tanks shown in Fig. 6 is applicable.In Japan, the tank model without soil moisture structure can give fairly good results because it is always very humid in Japan. However, for most river basins, the tank model with soil moisture structure shown in Fig. 7 must be applied. The assumed soil moisture structure is composed of two parts, the primary and the secondary soil moisture storages. When the primary soil moisture storage is not saturated, the water is absorbed from the lower tank and there is water transfer between the primary and the secondary soil moisture storages. These two kinds of water transfer are given as shown in Fig. 7c.In regions with long dry season, there is no tree on mountain area or trees have no leave in dry season and vegitation covering can be found on plains or along rivers. In such regions, mountain areas become dry during the dry season, because water moves to lower part of the basin by gravitation. To simulate such a basin, the basin is divided into zones each of which is simulated by the tank model. The tank model of 4X4 type shown in Fig. 8 is derived under such a consideration. During the dry season, zones become dry from mountain side and no evapotranspiration occurs in dry zones. In this model real evapotranspiration from the basin decreases with time corresponding to the dry condition of zones, i.e. areal real evapotranspiration of the basin decreases automatically.The tank model is considered as a black box model without physical meaning by most hydrologists. However, we can ask ourselves, if it is a mere black box, how can such a simple tank model successfully simulate river discharge from high flood to low base flow? There must be some physical meaning in the tank model. Very recently, we were able to find the phenomenon to prove the existence of two kinds of water storage corresponding to the top and the second tank of the tank model by analysing the record of crustal tilt meters affected by rainfall (Fig. 9). The crust is some sort of spring balance which weighs' and so measures the groundwater storage (Fig. 10).