Origin and dynamics of groundwater salinity in the alluvial plains of western Delhi and adjacent territories of Haryana State, India

Abstract

Abstract:Groundwater salinity is a widespread problem and a challenge to water resources management. It is an increasing concern in the alluvial plains of Delhi and neighbouring Haryana state as well as a risk for agricultural production water supply and sustainable development. This study aims to identify potential sources of dissolved salts and the driving mechanisms of salinity ingress in the shallow aquifer. It combines a comprehensive review of environmental conditions and the analysis of groundwater samples from 25 sampling points. Major ions are analysed to describe the composition and distribution of saline groundwater and dissolution/ precipitation dynamics. Density stratification and local upconing of saline waters were identified by multilevel monitoring and temperature logging. Bromide-chloride ratios hold information on the formation of saline waters, and nitrate is used as an indicator for anthropogenic influences. In addition, stable isotope analysis helps to identify evaporation and to better understand recharge processes and mixing dynamics in the study region. The results lead to the conclusion that surface water and groundwater influx into the poorly drained semiarid basin naturally results in the accumulation of salts in soil, sediments and groundwater. Human-induced changes of environmental conditions, especially the implementation of traditional canal and modern groundwater irrigation, have augmented evapotranspiration and led to waterlogging in large areas. In addition, water-level fluctuations and perturbation of the natural hydraulic equilibrium favour the mobilisation of salts from salt stores in the unsaturated zone and deeper aquifer sections. The holistic approach of this study demonstrates the importance of various salinity mechanisms and provides new insights into the interference of natural and anthropogenic influences.

Groundwater management options in North district of Delhi, India: A groundwater surplus region in over-exploited aquifers

“…Alternatively in semi-arid climatic condition of the area repeated evaporation during peak summer and subsequent dilution during monsoon rains could be leading to leaching of salts in groundwater thereby enriching salinity of soil and groundwater. Lorenzen et al (2012) had similar observations on salinity enrichment in alluvial plains of western Delhi and adjacent Haryana. The other major chemical constituents of fresh groundwater in the district are mostly within the permissible limit prescribed for drinking purposes (BIS, 2003).…”

“…These higher salinity areas have minimal groundwater movement and the stagnant groundwater reacts with the clay materials resulting in the enrichment of salinity in the groundwater of these regions. In other areas of Delhi and adjacent regions, such occurrence of higher salinity in groundwater has been attributed to improper flushing (Shekhar et al, 2005;Lorenzen et al, 2012). Alternatively in semi-arid climatic condition of the area repeated evaporation during peak summer and subsequent dilution during monsoon rains could be leading to leaching of salts in groundwater thereby enriching salinity of soil and groundwater.…”

Integrated hydrogeochemical, isotopic and geomorphological depiction of the groundwater salinization in the aquifer system of Delhi, India

“…, 1983, Lorenzen et al, 2012, Panno et al, 2006. The high ratios (substantially greater than the seawater ratio) indicate halite dissolution source or industrial source of NaCl with low Br.…”

“…al., 2007).The main controversy includes the initial sources of water and the processes by which these waters acquired their conductivity in the order of 10 4 µS/cm. Many researchers suggested that the chemical composition of salinity in many deep basins resembles evaporated seawater which interacted with the sedimentary rocks and/or has subsequently mixed with seawater or meteoric water; while others indicated that salinity in several basins originated from meteoric water and not from seawater (Craig 1961;Land and Prezbindowski 1981;Knauth 1988, Lorenzen et al, 2012. Various studies have been conducted to find the most evident processes to explain different level of salinity in the groundwater (Mehta et al, 2000;Vengosh et al, 2002;Bennetts et al, 2006;Russoniello et al, 2013); where explanations for mechanisms allowing meteoric waters to become saline were mainly focused on salt dissolution.…”

Nitrate contamination of riverbank filtrate at Srinagar, Uttarakhand, India: A case of geogenic mineralization

“…However, there is a need for further geological investigations to identify the source and nature of these minerals in the region. In addition to availability of mineral in an aquifer, mineralization of groundwater also depends on the groundwater dynamics due to seasonal cycles as well as due to anthropogenic interferences (Lorenzen et al, 2012). Construction activities and increased uptake of groundwater can increase fluctuation in the groundwater flow and water level which can increase dissolution of minerals from the unsaturated zone as well as deeper zones.…”