Open access publications in the SLU publication database

Abstract

This study was made within the Management of Acid Sulphate Soils Project (MASSP) and was carried out at Tan Thanh Experimental Farm. The Mekong delta, situated in the southern part of Vietnam, is an increasingly important area for agriculture and aquaculture in Vietnam. Approximately half of the area is covered with acid sulphate soils. These soils give rise to problems because of their acidity which effects rice cultivation and water quality negatively. Due to these problems there is a need for better understanding of the water balance and the groundwater movements in these soils. The objective of this study was to study the saturated horizontal hydraulic conductivity, K, and the effective porosity, S, of the soil, in order to provide data to the physical and chemical models developed by MASSP. Steady state pumping tests gave K-values between 12 and 37 m/day and transient flow pumping tests gave K-values between 12 and 41 m/day. Estimated mean K was 23 m/day for both methods which is a somewhat higher value than previous measurements have indicated. The estimated effective porosity varied between 0.006 and 0.080. Guyon's and Theis' methods of calculation gave mean values 0.008 and 0.030 respectively. Both methods for calculating K are sensitive to variations in depth ofthe aquifer. A sensitivity analysis was performed to analyse how sensitive a computer model of the soil can be to variations in K, and thereby how important reliable K-values are when simulating water flows through the soil.