14. Sustainable exploitation of fresh groundwater lenses of the pleistocene aquifer in Nam Dinh province, Vietnam

Abstract

Fresh groundwater lenses of the pleistocene aquifer in Nam Dinh province are mainly found in the East, Southeast districts of the province (e.g. Hai Hau, Nghia Hung, a part of Y Yen, Truc Ninh, Nam Truc and Giao Thuy) with the total area of ​​761 km². The fresh groundwater lens provides drinking water for people in the area with an average flow of 97.989 m³/day. Recently, along with the socio-economic development, the demand for groundwater exploitation in the area has increased, leading to the possibility of groundwater depletion and saltwater intrusion. This study assesses the sustainable exploitation of groundwater in the pleistocene aquifer based on 6 criteria, including recoverable groundwater resources per capita (I1); total amount of groundwater resources exploitation/quantity of supplied resources for groundwater (I2); total amount of groundwater resources exploitation/total amount of groundwater resources (I3); Total amount of groundwater for domestic use/total amount of water for domestic use (I4); groundwater depletion index (I5); and groundwater vulnerability index (I6). The results showed that the groundwater exploitation reserve for the whole region is 410.398 m³/day. The calculated indicators indicated that 7/10 areas (according to administrative boundaries of Vu Ban, Nghia Hung, Nam Truc, Truc Ninh, Xuan Truong, Giao Thuy, and Hai Hau) are unsustainable exploitation areas. From studied results, a map for sustainable exploitation of groundwater was established in order to support the management, licensing and orientation of groundwater exploitation in Nam Dinh province.