Sedimentary Characteristics of Shallow Aquifers and Suitability to Irrigation in the Drought Season: The Case of the Fruit Tree Area in Ben Tre Province, Mekong River Delta

Abstract

In Ben Tre province, shallow groundwater found at a depth of 8 to 60 m is exploited for domestic use and for irrigation of crops in rural areas. The water wells have different depths and are usually moderately to high contaminated with iron alum, moreover the saline- brackish water is at different depths and locations. In recent years, due to the effects of climate change and drought, the problem of drinking water and irrigation for planting is an urgent need. The study determined the distribution characteristics of aquifers, the environment for forming sediments and analyzed some chemical indicators of water for crop irrigation. This study shows that shallow groundwater is clarified and consisting of the Holocene (qh) and upper Pleistocene (qp3) aquifers from 8 to 60 m in depth. The Holocene aquifer consists of fresh water commonly found at of 8.5-17.5 m in depth, and saline- brackish water appearing by layers and lenticular are commonly found at about 25- 35 m in depth. Fresh water is usually found in the fluvial flat, channel and estuary facies, and saline - brackish water is in the tidal flat, delta front and pro-delta facies belong to the subaqueous delta plain. It suggests that sedimentary facies in boreholes and geological cross-sections play an important role in determining distribution characteristics and water quality, clarifying the distribution of fresh and saline water in Holocene sediments in the study area. This result can be referenced for research in the Mekong River Delta and other regions. Shallow aquifers have not great thickness, uneven water quality, cannot provide concentrated water. However, the water source has an important meaning in providing water for agricultural irrigation in the drought season, especially in the fruit tree area in Ben Tre Province.