Hydrological and hydrogeological characteristics and environmental assessment of Hashilan Wetland, a national heritage in NW Iran

Abstract

In the present study, 6 water and 16 sediment samples were collected from Hashilan Wetland (Kermanshah Province, Iran) to specify physio-chemical properties of water and sediment and to evaluate the water pollution load with reference to the water physicochemical parameters. According to the Piper diagram, Ca2+–Mg2+–HCO3− hydrochemical facies is dominant due to calcium carbonate dissolution in the geological formations of the study area. The wetland water had a natural to slightly alkaline pH. Although TDS and EC of the water samples fall under freshwater category, their values were higher downstream of the wetland as a result of stagnant water, low water depth, more evaporation, and impact of agricultural runoff. Based on the water quality index (WQI), all water samples were ‘suitable’ for irrigation purposes, while 50% of the samples were ‘unsuitable’ for drinking. Comprehensive Pollution Index (CPI), and Sodium Adsorption Ratio (SAR) also indicated suitability of the wetland water for irrigation. According to the Wilcox diagram, salinity is higher downstream of the wetland due to introduction of agricultural runoff. It can be concluded that the wetland water could be used for irrigational purposes, but regular monitoring is recommended to promote sustainable use of natural resources and conserve the vulnerable aquatic ecosystem.