Simulation of flow headloss and chlorine decay using epanet model for maralal water distribution network in Samburu County, Kenya

Abstract

Majority of people in developing countries do not have access to clean and potable water due to inadequate supply and distribution system challenges. While the rationale of water distribution systems is to deliver to each consumer safe drinking water that is adequate in quality and quantity at an acceptable delivery pressure, this has been a major drawback for many distribution networks. In addition, the design spans for many urban and peri-urban water distribution networks managed by the Water Service Providers (WSPs) are being exceeded without augmentation. Maralal water distribution network is one of such distribution systems with poor system performance that has been the main contributor of high Non-Revenue Water (NRW). This coupled with significant mismatch between water supply and Water demand makes Maralal Water and Sanitation Company to resort to hedging/intermittent flow leading to water rationing. One of the Ways of predicting the flow dynamics within the distribution system is the use of hydraulic simulation models. This study therefore applied the Environmental Protection Agency Network (EPANET) simulation model to predict the dynamic state of the hydraulics and water quality status for Maralal water distribution system operating over an extended period of time. The general objective was to simulate water flow for Maralal water distribution system using the EPANET model for efficient planning, operation and maintenance protocol for the system. The parameters simulated were flow, headloss and residual chlorine. The model flow calibration results from four statistical criteria; Nash-Sutcliffe model efficiency coefficient (E), Sum of Squares Error (SSE), Percentage Bias (PB) and Root Mean Square Error (RMSS) of 0.99, 0.01, 0.05 and 0.03 respectively show that the model performed within acceptable range of the selected statistical criteria. The model was validated with Day l and Day 3 flow rate data for PIPE l in County zone. The findings of this study were: The roughness coefficients for a water distribution network that contribute to erratic pressure-dependent flows could be detennined at any time using the regression analysis of the measured head loss and flow rate, EPANET model predicted the steady and dynamic hydraulic parameters for the current and future water distribution systems and Chlorine decay with respect to pipe diameter impacts on hydraulic perfonnance and quality of water in a distribution network. The results from this study would assist water service providers and managers to make informed decisions in relation to Water distribution system planning, operation and maintenance to achieve the desired Water demands now and in the future.