Water Supply Configuration and Water Losses - Nikšić Waterworks Case Study

 

Aleksandar Daničić1, Dejan Dimkić1, Darko Kovač2, Goran Mitrović1 and Ana Đačić1

 

 

1 Jaroslav Černi Institute for the Development of Water Resources, Jaroslava Černog 80, 11226 Pinosava – Belgrade; E-mail: This e-mail address is being protected from spambots. You need JavaScript enabled to view it

2 Public Utility Company "Waterworks Nikšić", Hercegovački put 4, Nikšić, Montenegro

 

Abstract

Nikšić is the second largest city in the Republic of Montenegro, and the drinking water supply is secured from a nearby carstic groundwater resources. This paper provides an overview of activities related to defining of measures which will lead to a gradual increase in reliability and efficiency of the water supply system operation. This included analyses of the present condition of the water supply system, water consumption and water losses in the system, which led to the development and calibration of a water supply distribution system model. Additional field investigations were performed in order to further investigate the current levels of water consumption and water losses in the system and provide a relevant data set for calibration of the model. Analyses revealed a high level of water losses, and various measures have been proposed aiming, not only to reduce water losses, but also to reduce power consumption and improve efficiency and reliability of the water supply system operation.

Keywords: water supply, water losses, distribution network, pumping station, water tank, model calibration.

 

Introduction

Water losses in water supply distribution systems depend on a few general factors, including (AWWA 2009, Alegre et al. 2006, WSA/WCA 1994):

  • Problems related to billing of water consumption and collection of water bills, resulting from the existence of a large number of defective water meters in the water supply distribution system, as well as poor practices in data processing and handling;
  • The imperfections of pipe materials and joints;
  • Illegal (unauthorized) water consumption.

Procedures for water loss detection and management have been defined on the basis of experience in this field and have generally included the following activities (AWWA 2009, Alegre et al. 2006, WSA/WCA 1994):

  • The collection of all relevant data on the system, including physical parts of the system (pipes, tanks, pumping stations, valves, etc.), water consumption and system management;
  • The division of the system into zones of consumption (district metering areas - DMA) characterized by a limited number of water entry points - connections to the water supply system (one if possible);
  • The development of a simulation model of the water supply distribution system, field measurements of flows and pressures and calibration of the model of the present condition of the system;
  • The model-based analysis, including model calibration and analyses of the system under certain characteristic conditions, for purposes of identifying parts of the system where significant occurrence of loss may be expected and for assessing the needs for future detailed field investigations;
  • Flow and pressure measurements within the defined DMAs, followed by concurrent water meter readings and modeling, in line with standard procedures (balance method and night flow method).

The recommended methods of real loss detection are based on a gradual detection of leakage locations, which involves the initial analysis of the condition in the entire system, followed by an iterative reduction of the analyzed areas and, finally, field detection of leaks and repair of defects. Activities involve simultaneous field measurements and analysis on simulation models.

Application of the recommended methods has proven to be successful in practice, as it has led to the repair of defects and reduction of losses in numerous cases. However in some systems, these methods may be insufficient, especially in those where the configuration is such that it promotes instability in flow and pressures within the distribution system, as is the case for the Nikšić water supply system.