The Red river delta plain is the second largest delta in Vietnam and is located in the North of the country with an area of 14,860 km² and residing more than million inhabitants. Groundwater is mainly exploited in Quaternary sedimentary aquifers with a total discharge of about 3 million m3 /day. | BÀI BÁO KHOA HỌC USING ISOTOPE TECHNIQUE TO ESTIMATE GROUNDWATER RECHARGE IN THE RED RIVER DELTA PLAIN Le Viet Hung1 Pham Quy Nhan1 Tran Thanh Le1 Dang Duc Nhan2 Abstract The Red river delta plain is the second largest delta in Vietnam and is located in the North of the country with an area of 14 860 km and residing more than million inhabitants. Groundwater is mainly exploited in Quaternary sedimentary aquifers with a total discharge of about 3 million m3 day. Some localities have shown signs of over-exploitation such as in Hanoi and in Nam Dinh which may lead to related problems such as depletion subsidence saltwater intrusion and water pollution. In order to be able to sustainably exploit groundwater the groundwater recharges need to be estimated. There have been many studies referring to different methods of estimating the groundwater recharge in which the most effective one is the isotope technique. Field trip and water sampling for chemical compositions stable isotopes 18O 2H and radioactive 3H analysis were also implemented. Ground recharge rate in the range from 77 to 440 mm year was estimated by using isotope analysis and interpretation Keywords Groundwater recharge Red river delta plain stable isotopes 18O 2H radioactive isotope 3H. 1. INTRODUCTION the place with the largest population density in the The groundwater recharge of a certain area is a country MPI 2020 . Groundwater is a valuable fundamental component of the balance of a certain resource that has been exploited quite a lot in this catchment which contributes to the sustainable region with total exploitation discharges of about exploitation of water resources in general and 3 000 000 m3 day MONRE 2015 . Many groundwater in particular. It is hard to measure problems such as ground subsidence pollution directly so Lerner et al. 1990 Scanlon et al. depletion and saltwater intrusion related to 2002 reviewed numerous methods ranging groundwater have also occurred in this area . widely in .
