Quantifying spatially explicit reductions in wheat irrigation demand across the Indus basin through laser land leveling

Abstract

Farmers in the Indus River Basin often irrigate their crops using surface irrigation on uneven fields, resulting in reduced irrigation performance and high irrigation demand. Assessment of irrigation performance is essential for reducing irrigation water use and identifying viable solutions. This study assesses the efficacy of Laser Land Leveling (LLL) in improving irrigation performance indicators and reducing water demands for wheat crops in the Indus basin. We used the calibrated irrigation simulation tool, Windows tool for Surface Irrigation Field Research (WinSRFR) to simulate irrigation water use after laser land leveling and conventional land leveling. Subsequently, an estimate of the potential reduction in irrigation water demand due to LLL was spatially extrapolated using process-based crop-hydrology model, Lund-Potsdam-Jena managed Land, (LPJmL). Results showed the highest potential reduction in irrigation demand on sandy loam fields (50%), followed by loam fields (33% reduction) and clay loam (15%). The total potential reduction in irrigation water demands due to LLL for wheat in the Indus basin estimated to 4 to 6 km3. The northwestern and eastern regions showed higher water-savings compared to the rest of the Indus basin. LLL not only reduces irrigation water demands at the basin scale but can also achieve application efficiencies equivalent to those of drip and sprinkler irrigation. With lower costs and fewer training needs, and higher yields due to better distribution uniformity, LLL can become one of the preferred adaptation options for widespread implementation in the Indus river basin.