Evaluating the impact of climate change on irrigation canal performance

Abstract

AbstractIrrigation canals are the main systems that convey water from sources to demand nodes. Their performance is affected by climate change. In this research, the effect of climate change on temperature and precipitation was investigated in the Aghili irrigation network over the base period 1994–2017, and the Aghili east canal performance was consequently assessed. To this end, the climate data were first assessed by the Mann–Kendall test to determine trends. Then, changes in temperature and precipitation were simulated using HadGEM2‐ES in the Long Ashton Research Station Weather Generator (LARS‐WG) under two representative concentration pathways (RCPs) of 2.6 and 8.5 over the periods 2021–2040 and 2041–2060. CROPWAT8 was used to calculate the crop water requirement and irrigation hydromodule, and the turnout flow in the considered canal was calculated next. Finally, the canal was simulated and assessed. The results showed that the maximum temperature, evapotranspiration and turnout flow increases are 3.7°C, 1.45 mm/day and 39 L/s, respectively, related to the base timescale. Additionally, the adequacy performance decreased to 0.768 from 0.986, leading to a maximum extra water requirement of 15.1 million m3/year in the Aghili east canal under a pessimistic scenario.