Sustainable use of integration of ground and surface waters

近年来经济的增长和城市面积的扩大，使需水量迅速增加，造成了水污染、地面沉降等水文环境的破坏。因此，如何构建平衡的水资源供需体系和保护水文环境是当前的水问题。本研究通过对琉球群岛、熊本地区和山之平原的实地调查，探讨了具体地区的水管理问题。琉球群岛由高渗透性的石灰岩组成，地下水是主要的水源。宫古岛是一个平坦的山丘，没有河流，通过修建地下坝利用地下水灌溉。同时，建立了地下水开发与保护管理体系。在位于麻生山脚下的熊本地区，地下水被高度开发以供市政使用。在山之平原，增加供水的措施包括：建设多用途水库、流域内调水和流域间调水。虽然大规模的供水系统已经建成，但在少雨期仍难以保证充足的供水。要实现全年供需平衡，就必须统筹利用地表水和地下水，保护水文环境，合理管理土地利用。

The recent economic growth and the expansion of urban areas have caused the rapid increase in water demand, and it resulted in damages of the hydrological environment such as water pollution and land subsidence. Thus, the water issues are to construct the balanced water supply-demand system and to conserve the hydrological environment. This study discusses the water management in the specific area based on the field survey, which is conducted in the Ryukyu islands, the Kumamoto area, and the Sanuki plain. The Ryukyu islands consist of limestone with high permeability, and groundwater is a major water source. Miyako island is flat hill without rivers, and groundwater is used for irrigation by constructing the underground dam. At the same time, the management system is established for groundwater development and conservation. In the Kumamoto area located at the foot of Mt. Aso, groundwater is highly developed for municipal supply. In the Sanuki plain the measures to increase the water supply are performed as follows: construction of multi-purpose reservoirs, water transfer within the basin, and inter-basin water transfers. Although the large scale system of water supply has been built, it is still difficult to supply adequate water during the period of little rainfall. Keeping the balance of supply and demand throughout the year, it requires the conjunctive use of surface and ground water, the conservation of hydrological environment, and the wise management of land use.