An-Najah Staff

The City of Nablus relies on groundwater resources for water supply. The utilization of these resources is through groundwater wells and the naturally emerged springs. These resources are well distributed throughout the municipality boundaries and the nearby communities. Water is collected in central reservoirs and later distributed to the designated areas through a huge water distribution network where the total length of the pipes exceeds 340 km. In 1995, Nablus Municipality started off a water quality monitoring program for its water resources and the water distributed by the network. The on-going monitoring program focuses on measuring chlorine levels and the bacterial re-growth. To assure water free from bacteria and other polluting organisms, chlorine is added to the water at different locations. However, due to the expansiveness of the network, the remoteness of the water sources, and the weariness in the network pipes and joints, chlorine concentrations were found to be way below the minimum allowable limits. This study aims at investigating the disinfection problems that exist in the water network of Nablus. In order to delineate the segments of the network where problems do exist, historic quality data for the last nine years (1996-2005) was collected, spatially referenced, dated, and digitized. A composite database was thus created to facilitate the spatial and temporal assessment. Thereafter, disinfection methods used by the Water Department at the Nablus Municipality were investigated. In order to assess the current chlorination practices, a water network quality model was developed for a selected area within the Nablus drinking water network. The model simulates the water flow in pipes, pressure at the supply nodes, and chlorine concentration distribution in pipes and nodes. Results of the analysis of the composite database showed that residual chlorine concentrations in many areas were low. This has led to the bacterial growth in these areas as indicated by the total and fecal coliform. Model outcome showed that chlorine concentration varies from location to location in the network, which is in agreement with field observations.