A Review of Recent Hydrological Researches Related to Agricultural Activities in Japan

Abstract

 This paper reviews recent decades’ researches on impact of agricultural activities on water and material circulation and its countermeasures, those on numerical modeling of water and material circulations considering agricultural activities. For impacts of agricultural activities, flood discharge control by “Paddy Field Dam” and flood discharge control function of mountainous and intermountain areas were reviewed as flood mitigation function of farmlands, and pollution loads from farmland and effect of cycling irrigation on water quality improvement was as water quality control function of farmland. For numerical modeling of water and material circulations in river basins including farmland, examples of a numerical model of water circulations including irrigation and drainage management of paddy field in Monsoon Asia, and application example of evaluation of climate change impact on water usage for agriculture was introduced. Moreover, application of Irrigation Management Performance Assessment Model and application of the model to arid area are introduced as a comprehensive water circulation model and its application.