Gis-Based Multi-Criteria Analysis For Optimal Site Selection For Wastewater Treatment Plant:(The Case Of Bahir Dar Town,Ethiopia)

Abstract

The siting of wastewater treatment plant is an extremely complex task mainly due to the fact that the identification and selection process involves many factors and strict regulations. For proper identification and selection of appropriate sites for wastewater treatment plants careful and systematic procedures need to be adopted and followed. The main objective of this research was to find the optimal location of wastewater treatment plant by using the GIS-based MCA approaches in Bahir Dar town, which are environmentally and economically suitable. The present study had integrated environmental and economical criteria considering road networks, rivers/streams, lake, geology, soil, slope, elevation, wind direction, groundwater wells, groundwater table, rural settlements, urban settlements and land use/ land cover for selecting a suitable wastewater treatment plant site with in the study area. The relative weights of criteria were estimated using AHP and criteria maps were developed by using GIS spatial operations. Weighted linear combination was used to integrate weight with the factor maps. The final integration of weighted factor map and constraint map produced an overall wastewater treatment plant suitability map. The wastewater treatment plant site suitability map was presented in four suitability index such as highly suitable, moderately suitable, low suitable and unsuitable. The result shows that around 6.08% area is highly suitable for wastewater treatment plant site, 1.83% is moderately suitable, 0.61% of study area has low suitablility and 91.48% area is unsuitable for wastewater treatment plant site. Among the highly suitable areas, five sites were selected and revaluated in terms of road network, river/streams, lake, geology, soil, slope, elevation, wind direction, groundwater wells, groundwater table, rural settlements, urban settlements and land use/land cover to select the optimal suitable site. Finally, site 4 was proposed as the most preferable option for the construction of the wastewater treatment plant site with the minimum effects on economic, environment risk and public health.