Assessment of water quality parameters due to Longitudinal Salinity inundation at Indus Delta: A case study of Kharo Chan, District Sujawal

Abstract

Abstract Deltas are landforms which are formed at the regions where a river meets an ocean. When the freshwater of a river joins the saline water of an ocean, a transitional state of water is obtained. This zone of transition varies on the quantity of freshwater entering the ocean and the quality of both of the waters. Indus River is facing severe challenges due to climate change which has resulted in reduced water flow in the river. Consequently, sea water intrusion takes place which causes coastal erosion, stunted mangrove growth and the narrowing of the river towards the seaside. The groundwater in the deltaic regions is unfit for drinking, forcing reliance on surface water. Sindh Province, particularly the coastal regions, suffers from severe water quality problems, affecting approximately 41% of the population. This research aims to evaluate the physiochemical parameters of water in the Indus River to identify the zone of salinity inundation and determine safe zones for accessing surface water in the Indus Delta in the Sujawal district. Water samples were collected from Khobar Creek, ending in the Arabian Sea in the areas of Shah Bandar and Kharo Chan at an approximate interval of 5 km. These samples were analysed for various physical and chemical properties. Then these properties were compared spatially to develop a relationship between distance and quality. TDS values are observed in between 21450 mg/L and 900 mg/L, pH was between 6.66 and 7063, EC of the samples varied from 33000 to 1385 µS/cm, Acidity values were in between 921.14 and 399.84 mg/L, Hardness was in the range of 3654 to 192 mg/L, and Turbidity was in between 21 and57 NTU. It was revealed from the results that seawater is having a severe influence upto 15 km from the mouth of the creek in which not a single parameter except pH was in accordance with WHO recommendations. In the interval of 15 to 30 km, some properties of water were in accordance with WHO recommendations, while some of them were exceeding the limits. It has been concluded that turbidity was improving while going toward the ocean. TDS, hardness and chloride concentration was increasing as water is getting closer to the sea while PH was found almost unaffected. The findings emphasize the need for addressing environmental degradation, social hardships, and economic challenges caused by these water quality issues. Ultimately, the quality of water is crucial for various activities, and its suitability for specific purposes is of utmost importance.