EVALUATION OF DOWNSIZING AND SUSTAINABILITY OF WATER DISTRIBUTION NETWORK IN A MIDDLE SIZED-CITY

Abstract

 Using data of water distribution network on CAD and revenue earning water of 14 water distribution areas in a middle sized-city, the amount of revenue earning water and length of water distribution network with 250m mesh were calculated and the utilization efficiency of water distribution network was estimated on a GIS map. Distribution pipe of 303km (~30% of total length) distributed in a seaside area with altitude of 0-10m and in a mountainside area with that of 70-200m was shown to be relatively low utilization efficiency. Estimated operating revenue and expenditure until FY2058 showed that water users need to additionally pay ~1,250JPY/pe/month when ~70% of water distribution network is replaced, whereas they pay ~1,600JPY/pe/month when current water distribution network is replaced according to the prescribed schedule. However, the additional payment is reduced to be ~580JPY/pe/month when ~70% of water distribution network is replaced and 150 thousand population can be maintained as the city aims. We conclude that operating expenditure reduction and population decline control become important even if water distribution network is downsized.