Abstract

Water quality can be identified as the main agent of human health. Different approaches and techniques can be used to analyze groundwater quality. Among them, Geographical Information Systems (GIS) is one of the approaches that can be utilized to analyze water quality levels in a spatial context and it provides more powerful tools that can be interpreted the spatial variation of the water quality parameters over the geographical space. Accordingly, the study was conducted to analyze spatial variations of the water quality in drinking wells in the Buttala Divisional Secretariat (DSD) which is an agricultural area in the dry zone. The methodological procedure is extremely important in this type of research thus, the spatial Multi-Criteria Decision Analysis (MCDA) procedure was used. Multi-criteria analysis has been widely applied to solve decision-making problems related to the environment, and natural resource management. In the study, Analytic Hierarchy Process (AHP) and MCDA integrated approach were used to visualize the spatial patterns of the water quality in the study area and to formulate the water quality index map. To generate the water quality index map, pH value, turbidity, electrical conductivity (EC), florid, and nitrate of 48 water samples were collected from the domestic well and tube wells from 10 Grama Niladari Divisions (GND) in Buttala DS. The ArcGIS 10.3 software was used for spatial analysis like Inverse Distance Weighting (IDW) and kriging. The results revealed that 11.2% of the water of the drinking wells in the study area has a good fitness level, while 68.7% of wells show a moderate quality level. Out of the total samples is shown that 18.5% of wells had a poor-quality level, and 1.2% was found to be very poor for drinking purposes. And also, 0.4 % of the area is unsuitable for drinking. The study shows that geospatial techniques are more effective for studying the water quality in any area in an accurate decision support tool.

Keywords: Buttala, GIS, Groundwater, IDW, Kriging, Water quality