Evaluation of Water Losses in Unlined Canal: A Case Study of Malik Branch Canal, Bahawalnager, Pakistan

Abstract

Water is an essential component of nature for the survival of life on planet earth. It is the most valued reserve of nature. But supply of water on earth is not identical on all parts of globe. Also its characteristics and quality is changing in different areas. In the case of some areas it is not usable for drinking purposes as well as for irrigation. The two main source of water are surface water and ground water. Surface water has its uses as domestic and for irrigation supply. It is diverted from rivers to the irrigation systems such as canals and water courses with aim to irrigate fields. Now-a-days, with an increasing demand of water, due to the gradual increase in population, it is becoming a scared source from an abundant resource. Due to this increase in demand and scarcity in supply, it is being prominent to decrease water losses to make irrigation systems more and more efficient. This study undergoes to estimates the water losses in unlined canal with a purpose of providing estimation of water losses. Canal is used for supply of water from one location to other. In canal, different types of losses take place. Seepage and evaporation are the major water losses in an irrigation channel. The losses from canals need to be reduced to ensure the efficient performance of irrigation system and effective utilization of water. Seepage losses are main problem in earthen canal. There are methods to calculate these water losses. In this case, study the seepage losses & evaporation losses are determined also investigated the rate of water losses. There is a dire need to identify and prioritize the cause of losses in unlined canals so that rehabilitation and maintenance can be done accordingly. The Inflow and Outflow method was adopted to estimate the water losses on four sections of the selected canal. Average total water loss rate is calculated for four sections which is 1.74 x 10−3 cusecs/ft, whereas contribution of evaporation losses (during September to December) in total water losses is 1.22%. The amount of evaporation increases with the increase in temperature. It is observed from this research that there is 13.38% difference in water discharge between upstream and downstream of canal which badly affects the proper availability of water to irrigation lands at the tail, hence causes water scarcity.