Analysis of Conveyance Losses from Tertiary Irrigation Network

Irrigation canals are generally made through porous soil formations, since the soil is loose porous media – a huge amount of canal water is lost to conveyance losses. The situation becomes direr when these losses result in non-beneficial losses. The Sindh province of Pakistan has more than 70% saline groundwater, conveyance losses to such areas in the province not only become unusable but also creates water management problems. Perhaps the only cost-effective way to address these losses is canal lining. The present study was conducted in the command area of Belharo distributary, Sindh, Pakistan with an aim to determine the extent of losses from the tertiary irrigated network as these water channels are less considered in the literature with regards of conveyance losses. Using water balance method, conveyance efficiency and conveyance losses at 30% lined and 50 and 75% unlined length of the watercourses was observed. The results revealed that the tertiary irrigation channels face an average of 43% conveyance losses and major proportion of these losses is lost to non-beneficial losses from the study area. The study further suggests 75% lining of watercourses in order to minimize non-beneficial losses. This study also infers that with the use of geo-membrane lining, sizeable amount of fresh water can be saved. Doi: 10.28991/cej-2021-03091756 Full Text: PDF

Estimation and Canal Conveyance Losses in Pune District

Water is a very precious natural resource. When this precious resource moves through the canals certain part of the water is lost by seepage, evaporation etc. This loss is known as conveyance loss. In present paper, study of Nira Left Bank Canal (NLBC) is done which is situated in Pune district. Total length of canal is 162 Km out of which 30 Km is our study area. Discharge calculations at the head of canal and at 30th Km is done, two standing wave flumes are present at these two locations. Since last few decades, the extensive underutilization has been found in canal irrigation. This issue constitutes the serious lacuna in irrigational planning which often depicts the major problem about optimal water use. As per FAO Aquastat 2015 records for India, out of 91% of water utilized for agriculture purpose, 45% is getting lost under different types of conveyance losses from dam headworks till farms. The conveyance losses constitute the seepage and evaporation losses. Out of these, seepage is a quite significant loss in most of the water conveyance systems. Estimating conveyance losses using physical methods is quite difficult and involves lots of field work and calculations, whereas empirical and analytical methods will not accommodate site condition of respective study area. This study attempted to assess the conveyance loss of Nira Left Bank Bank Main canal with the help of a hydraulic model built on a spatial platform and verified with flow-monitoring events. The hydrospatial model was simulated to understand the canal behaviour and evaluate the conveyance losses. The results show Nira Left Bank Main canal has average 39.96% water conveyance loss.

Hydrospatial Modelling and Simulations for Assessing the Irrigation Canal Conveyance Losses

Since last few decades, the extensive underutilization has been found in canal irrigation. This issue constitutes the serious lacuna in irrigational planning which often depicts the major problem about optimal water use. As per FAO Aquastat 2015 records for India, out of 91% of water utilized for agriculture purpose, 45% is getting lost under different types of conveyance losses from dam headworks till farms. The conveyance losses constitute the seepage and evaporation losses. Out of these, seepage is a quite significant loss in most of the water conveyance systems. Estimating conveyance losses using physical methods is quite difficult and involves lots of field work and calculations, whereas empirical and analytical methods will not accommodate site condition of respective study area. This study attempted to assess the conveyance loss of Dudhganga Right Bank Main canal with the help of a hydraulic model built on a spatial platform and verified with flow-monitoring events. The hydrospatial model was simulated to understand the canal behaviour and evaluate the conveyance losses. The results show Dudhganga Right Bank Main canal has average 39.96% water conveyance loss.

Impact of Lined Canal on Shallow Tubewell Irrigation and Their Acceptability by the Farmers

The comparative conveyance losses between lined and unlined canals, impact of water saving on command area development and irrigation cost, and farmers’ acceptability of lined canal in shallow tubewell (STW) irrigation schemes were studied during 2010-11 Boro season at three upazilas: Manikgonj Sadar of Manikgonj district, Dhamrai of Dhaka district and Mithapukur of Rangpur district. The conveyance loss was measured using inflow-outflow method and focus group discussion (FGD) was carried out with the pump owners and farmers to assess the impact of water saving on command area development and the acceptability of lined canal technology. Average conveyance losses were found to be 41, 48 and 45% in the existing earthen canals; 18, 21 and 24% in improved earthen canals; and 12, 11 and 13% in pre-cast canals at Mithapukur (M1), Manikgonj Sadar (M2) and Dhamrai (D) schemes, respectively. The water saving did not increase the command area in any of the schemes but reduced the irrigation time and saved fuel requirement for irrigation. On an average, 32, 23 and 30% fuel were saved by improved earthen canals where as 45, 46 and 48% were saved by pre-cast canals for M1, M2 and D schemes compared to earthen canal. The benefit-cost ratios of improved earthen canals were 1.36, 1.38 and 1.30 where as 3.36, 4.28 and 3.34 by pre-cast canals for M1, M2 and D schemes, respectively. The internal rate of return (IRR) from the investment on water distribution was over 50%. The lining technology was acceptable to pump owners, but did not impress the farmers who share the crop with the pump owners as price of irrigation or pay on the basis of irrigated area. In order to make the technology acceptable to the farmers, polices must be framed to share the benefits of lining by the pump owners with the farmers by reducing the price of irrigation water or through financial support of GO and NGOs for efficient use of STW irrigation system in Bangladesh.The Agriculturists 2014; 12(2) 116-125