222893e

TRANSBOUNDARY WATER MANAGEMENTTransboundary groundwater resourcesmanagement implemented in theKumamoto region of JapanTadashi Tanaka, Department of International Affairs, University of Tsukuba, JapanThe Transboundary Groundwater Resources Managementsystem is a typical groundwater management systemimplemented in the Kumamoto region of Japan. Thesystem was introduced in 2004 and, in cooperation with neighbouringmunicipalities, the Kumamoto City government hascreated a unique funding system to encourage artificial groundwaterrecharge projects through abandoned rice paddy fieldsin neighbouring towns outside the city boundary. These willenable sustainable use and management of regional groundwaterresources and the passing down of this precious resourceto future generations. The groundwater management system isregulated by the Kumamoto City, local governments and the citypeople. It provides a good example for assessing and managingaquifer systems crossing regional administrative boundarieswithin a given country, as well as of a typical self-governancesystem for managing regional groundwater resources.In addition to aquifers that continental countries share with othercountries, there are aquifers crossing regional administrative boundarieswithin a given country. These aquifers are distributed in differentparts of Japan which have diverse regulations and social conditions.Transboundary aquifer crossing 13 local governments inthe Kumamoto regionSource: T. TanakaThe monitoring and management of such aquifers needat least the same amount attention as those of transboundaryaquifers between national boundaries.There is currently no unified national law in Japan tomanage groundwater resources except for preservationof the land against subsidence. Therefore, the right ofgroundwater resources belongs to the landowners.Two groundwater laws, the Industrial Water Lawintroduced in 1956 and the Law on Regulating theExtraction of Groundwater for Use in Buildings introducedin 1962, are effective across Japan, but practicalapplication of these laws to a specific area has beendecided by local government. For example, the TokyoMetropolitan Government has succeeded in reducingthe rate of land subsidence by converting waterresources for industrial use from groundwater tosurface water, and by providing legislative guidanceto save groundwater resources in factories and buildingsdepending on these two laws. However, borderingprefectures are still suffering from land subsidence.Besides preservation of the land against subsidence,however, a new concept is now growingamong Japanese municipalities, communities andcitizens. They see groundwater as a shared naturalresource that needs to be managed on that basis.One typical groundwater management system is theTransboundary Groundwater Resources Managementsystem implemented in the Kumamoto region ofJapan. The artificial groundwater recharge projectproposed by this system, using abandoned rice paddyfields, is considered an excellent example of groundwatermanagement in Japan.The vast groundwater reservoir and regionalgroundwater flow system cover 13 local governmentsincluding Kumamoto City, with an area of around1,040 km 2 and 1 million residents. All the water forthe city’s residents is supplied from these abundant,pure and crystal-clean groundwater resources. Most ofthe region is covered by pyroclastic deposits created bythe four major eruptions of Mount Aso between 0.26Ma and 0.09 Ma. There are two main aquifer systems,namely the unconfined aquifer (No. 1 aquifer) and theconfined aquifer (No. 2 aquifer). The No. 2 aquifer[ 88 ]