Study on assessing the impact of evaporation on the natural recharge in the Holocene aquifer of sand dunes in Ben Tre province, Vietnam

Abstract

On the surface of the terrain in Ben Tre province, sand dunes exist in the form of thin strips running parallel and facing the coastline, with a total distributed area of about 12,179 hectares. These sand dunes vary in size, with widths ranging from 100 to 620 meters and lengths from 1,200 to 7,200 m. The predominant geological component in these sand dunes is fine-grained sand with large pore sizes. The vegetation cover on these sand dunes is sparse, with numerous hours of sunlight throughout the year. The air temperature and surface evaporation are high, creating favourable conditions for the evaporation process from the groundwater surface. This study employs the direct evaporation measurement method using Lysimeter (LS) based on the water balance principle. The LS measuring station is located in Tan Thuy commune, Ba Tri district, Ben Tre province, to monitor the groundwater loss through evaporation, simulating real conditions with groundwater levels at depths of 0.5 and 0.9 m. The monitoring and calculations show that the total groundwater evaporation during the period from 1 June 2022 to 31 May 2023 is approximately 142.5 mm, equivalent to 24.9% of the natural recharge of the aquifer.