Theme 3-19-Impact of irrigation on the environmental geochemistry of groundwater from Sangamner area, Ahmednagar district, Maharashtra

Abstract

In an attempt to evaluate the impact of irrigation on the environmental geochemistry of ground water 136 samples from Sangamner area were analyzed. The chemical characteristics of ground water have been found to be dominated by Ca +Mg >Na + K -HCO3 + CO3 hydro-chemical types followed by Na + K-HCO3 + CO3 and Na + K - SO4 + Cl + NO3 indicating dominance of cation and anion exchange process on both spatial as well as temporal scales. Rapid chemical changes evidenced by diverse hydro-chemical characteristics in the irrigated agricultural zone have lead to faster chemical evolution of ground water. As against this, in the non-irrigated agriculture less hydro-chemical diversity reflected slow process of chemical evolution of ground water. In general, the majority of the ground water samples belong to medium conductive class I in non-irrigated agriculture and, medium conductive class II and high conductive class III in irrigated agriculture area indicating impact of irrigation.

Hydro-chemical diversity, salinization of ground water and boron toxicity has been identified as the impact of irrigation in the area. On the basis of TDS the ground water is classified as fresh, slightly saline to moderately saline and very saline in character. In general saline (slightly, moderately and very saline) ground water is confined to irrigated agriculture and that of fresh to non-irrigated agriculture zone. Increased salinization has caused large-scale variations in the hydro-chemical characteristics of water and increase in the concentrations of fertilizer derived constituents in ground water. Educating the farmers to adopt better farm management practices have been suggested to reduce the problem of environmental degradation.