Characteristics of hydrochemical and d2H, d18O stable isotopic composition to study saltwater intrusion in coastal aquifers in Danang city

The situation of saltwater intrusion in coastal aquifers in Da Nang city is greatly affected by urban planning, exploitation and water resources use. This article presents research data on hydrogeochemical characteristics and stable isotope composition, thereby determining the origin of groundwater in aquifers then study on saltwater intrusion. The relationship between δ2H and δ18O during rainy season shows that the water in the Holocene aquifer in Da Nang coastal area has isotopic composition similar to regional meteorological water and does not mix with seawater, the main source recharges to the aquifer is rainwater. During dry season, d18O in groundwater is low but d2H is enriched by recharged rainwater from higher attitude area and also affected by exchange with leakage water from landfills. The saline water in this aquifer tends to be washed by rainwater leading to the phenomenon of paleness and the area of salt water in the aquifer is gradually shrinking. These research results are very important in propose a solution for ground water extraction plan and control saltwater intrusion for groundwater