Changes in Groundwater Salinity and Nitrate Concentrations Due to Aquifer Recharge by Treated Wastewater: Korba Case Study

Abstract

The overexploitation of Korba aquifer mainly for irrigation purposes at a rate of 103 % caused a decrease in aquifer level in addition to its deteriorating water quality. Since July 2008, treated wastewater from Korba plant has been used to artificially recharge the aquifer at a site close to the treated wastewater plant. The purpose of this project is to develop a new sustainable water resource, to improve the groundwater bad quality and raise the piezometry of the coastal groundwater in this region.

Before starting the recharge, both groundwater and treated wastewater were monitored for their quality. The resulting mixture of groundwater and infiltrated treated wastewater is monitored since then. The changes in water quality before and after 3 years of recharge are followed for two significant parameters throughout the whole study zone: salinity and nitrates concentration, in an area of about 9 km² including both the recharge site and the treatment plant. There is no clear difference introduced by the recharge on nitrates very high concentrations as 90 % of the studied waters contain more than 50 mg L⁻¹ NO₃ unchanged and classified as bad or very bad quality waters. For salinity there is a slight decrease especially around the recharge area. In the light of these results, this ambitious project already shows positive effects for water and environmental management in the region.