DRINKING AND IRRIGATION WATER QUALITY ASSESSMENT IN DIFFERENT CLIMATIC ZONES OF BALUCHISTAN

Abstract

Water is essential for life. However, water quality defines water use. To develop water profile of Baluchistan, it was divided into seven zones (Northern Highlands -NH, Southern Highlands -SH, Quetta Velley -QV, Desert -D, Sibbi Plains -SP, Coastal Lasbella -CL & Coastal Gawadar -CG). These zones are based on geography, water availability and climate of the area. Total 106 water samples were collected from karaiz, groundwater, springs, and tube-wells. These samples were analysed considering 15 important water quality parameters (like EC, TDS, pH etc). The results revealed that Baluchistan water has a slightly alkaline pH. Spatial distribution of EC, TDS, TH, SO4 2−, Cl−, Na+ and K+ showed an increasing trend in concentration from highlands towards the desert and coastal zones. For anion, HCO3 − is predominant in NH, SH & QV, Cl− in D, CL & CG and only SO4 2− in SP. The cationic trend in overall zones assessed same as: Na+>Ca2+>Mg2+>K+ based on mean concentration. Apart from Pb in NH, SH, QV and SP, the physicochemical parameters met the drinking waters quality guidelines set by WHO, however, D, CL and CG were exceeded almost in all quality parameters. Moreover, all seven zones have high concentrations of Pb and low in fluoride. Furthermore, the drinking WQI shows poor to unsuitable category in all seven zones. Piper and Chadha diagram indicates the hydrogeochemical facies with most of the water samples from NH fall in Ca-Mg-HCO3 type and SH, QV and SP in Ca-Mg-Cl type, however, few samples lie in both types. D, CL and CG fall in the NaCl type of water. In NH, SH, QV and SP, major ion chemistry is controlled by rock-weathering while in D, CL and CG evaporation is dominant. Saturation indices suggests that dissolution of evaporates minerals and precipitation of carbonates minerals are the dominant process controlling the hydro-geochemistry. Chloro-Alkaline indices concludes, cation exchange is the main mechanism which controls the groundwater chemical composition. Similarly, irrigation water quality parameters such as EC, SAR, RSC, Na%, MH%, PI, SSP and KR, reveals that NH, SH, QV and SP have suitable water for irrigation and in D, CL and CG, the water is not suitable without proper treatment. Additionally, USSL and Wilcox diagram indicated that; NH, SH, QV and SP have “excellent to permissible class” water. However, D, CL and CG were dispersed in “permissible to unsuitable class”. Therefore, it cannot be used for irrigation without special management of salinity and sodic control. In terms of health risk assessment, the samples exhibit high values of health index and carcinogenic index with regards to Pb consumption via ingestion and dermal routes from seven zones of Baluchistan. It also depicts children more exposed than adults. Consequently, appropriate control measures and water purification programs should be executed to protect the health of the people of Baluchistan.