Abstract:
GIS-based Multi-Criteria Decision Analysis (MCDA) was carried out to prioritize drinking
water supply need in the Southern Region, Sri Lanka. The degree of water demand is
attributed to population density, water resources availability (Relative Water Balance), water
quality (Equivalent Water Quality Index) and new development (Population Pressure) of the
region. Spatial distribution of density of Grama Niladhari Division-wise (GND) population
was obtained from census data of 2,131 GNDs; assigned to the spatial distribution domestic
units available with Survey Department. Water resources availability of each GND was
figured out by plotting relative water balance with the aid of average annual rainfall data from
the Meteorological Department, Mean evaporation rate and inflow of rivers into the
designated research area. Water quality of relevant GNDs was calculated and represented as
Water Quality Index (WQI) with the aid of geochemical atlas produced by Dissanayake et al.
(1985) and NWSDB treated water quality data. Moreover, the new development of the
research area was symbolized with the development corridor stipulated under National
Physical Plan for 2050. Four raster files were prepared. To weight criteria, Analytic hierarchy
process (AHP) was adopted. To identify the prioritized patches, the weighted linear
combination of raster shapefiles was derived as a method of compensatory aggregation. It was
understood that a combination of water quality and population density was dominant in the
prioritization of water supply needs. The model identified the values as 0.47, 0.39, 0.07 and
0.07 for the main criteria, respectively for relative water balance, equivalent Water Quality
Index, population density and population pressure owing to new development. The output of
the research was the preparation of an automated GIS tool for prioritization of water supply
needs through the GIS model builder facility.
Citation:
Hewapathirana, A.S. (2021). Using GIS-based multi criteria decision analysis for prioratizing drinking water supply needs: an application to southern region in Sri Lanka [Master's theses, University of Moratuwa]. Institutional Repository University of Moratuwa. http://dl.lib.uom.lk/handle/123/20032