Gis- Based Multi-criteria decision analysis of Urban piped Water Demand: a case study of Lodwar town Turkana County, Kenya

Abstract

Water scarcity has become a global problem as a result of the ever-growing demand for water. The rapid urbanization, the population explosion and the growth of new settlements in small towns have increased the demand for water resources thereby leading to scarcity of available water resources. The water service providers are currently facing a bigger challenge of maintaining a stable and safe water supply of such towns to satisfy the growing demand. Lodwar town in Turkana County Kenya which largely depends on groundwater as the main water source is one such small town in a fragile environment facing such a high-water demand. The water service provider (LOWASCO) runs about 11 boreholes situated along the Turkwel River within a radius of about 10km. In this study, the Geographic Information System (GIS) and Multi-Criteria Decision Analysis (MCDA) methods were utilized in the mapping of residential piped water demand for the urban area for the period 2017 to 2019. The datasets used in this research included topographic maps, population data, urban spatial plan, area slope, Land use /Land cover change map as well as the detailed water utility infrastructure map. The methodology included the processing of satellite imageries for further land use analysis, Digital Elevation Model (DEM) was used to extract slope information. The resultant layers together with other data collected were projecting into the study area coordinate system WGS UTM Zone 36N. Saaty’s Analytic Hierarchy Process (AHP) method was applied in the calculation of respective weights for each factor influencing water demand as identified by the officers at LOWASCO and from the fieldwork. The analysis of the final Land use results indicated that the built-up areas are within the town centre and some parts of Kanamkemer area to the South forming two business centres with high water demand. Subsequently, areas around the proposed CBD/Town Centre have the highest population densities per km2 i.e. range (22555 – 37789) for respective unit areas within a range of (0.013833 - 0.014317) km2. The resultant water demand maps from records for the LOWASCO zones within period 2017 to 2019 indicated that Town B has the highest average annual water per capita demand of 86.595M3 whereas Nakwamekwi zone has the lowest average annual per capita demand of 8.497M3. The combination of main demand factors in the model produced a resultant map with different demand priority areas. The expanding urban areas/settlements to the South West (Kanamkemer) from the Town Centre and to the South East (Nawoitorong) should be given high priority in the future expansion of water distribution system.