Groundwater flow section modelling of salinisation processes in the Champhone Catchment, Savannakhet Province, Lao PDR

Abstract

A steady state, two-dimensional vertical section groundwater flow model has been developed for a salinised area of the Xe Champhone catchment in Savannakhet province, Southern Lao PDR. The area is underlain by evaporite beds and clastic sedimentary rocks of the Khorat Group that are the source of salt found in groundwater and surface soils. The Xe Champhone catchment is of interest because of plans for construction of several new reservoirs and extensive expansion of irrigated areas. This study provides an example of how a relatively sparse and limited data set has been used to construct and successfully calibrate a numerical flow model to investigate groundwater flow patterns and potential impacts of increased groundwater recharge on land salinisation. Results show the predominance of local flow systems and that deeper flow systems in contact with the rock salt layer operate over much longer time scales in the order of millions of years.