Changes in Water Resources Systems: Methodologies to Maintain Water Security and Ensure Integrated Management (Proceedings of Symposium HS3006 at IUGG2007, Perugia, July 2007). IAHS Publ. 315, 2007, 179-185.

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Impact of agricultural water management on a lake water budget: a case study of Lake Ikeda, Japan

YUJI ITO¹, KAZURO MOMII² & KEI NAKAGAWA²

1 United Graduate School of Agricultural Sciences, Kagoshima University, 1-21-24 Korimoto, Kagoshima 890-0065, Japan

du304001@ms.kagoshima-u.ac.jp

2 Department of Environmental Sciences and Technology, Kagoshima University, 1-21-24 Korimoto, Kagoshima 890-0065, Japan

Abstract Hydrological assessment of the effect of water utilization on a lake water budget is indispensable for proper water management. A model to estimate lake water level was developed for Lake Ikeda, Japan, and was applied to investigate the lake water budget and to examine the effect of agricultural water management on the lake water level. The calculated lake water levels agreed well with the measured levels for 1983–1999. The lake water level is generally highest from September to October and lowest in March, and is characterized by seasonal changes in the water budget components. Three simulations under hypothetical hydrological conditions revealed that river water supply in the agricultural water management system effectively compensates for the decrease in lake water levels caused by agricultural water use.

Key words freshwater resource; lake water budget; lake water level; water level simulation; water management; water use

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