A comparative study of seasonal irrigation demand and actual water supply in the Kaleshwaram project command area

This paper assesses seasonal and spatial mismatch between irrigation water demands and water supply in the Kaleshwaram Lift Irrigation Scheme (KLIS) command area, India where inflows dependent on the monsoon seasons, high evapotranspiration, timing of canal-release, and planting schemes have a combined effect on irrigation reliability. Based on multi-year occurrences data, which covers climate-data between 2000 and 2023, groundwater-observations data between 2015 and 2023, reservoir and canal-operation data between 2019 and 2023, and crops/land-use data between 2022 and 2023, the study generates a monthly water-balance framework, here variables specific periods were used according to the verified data availability. Digital Elevation Model (DEM)-based Geographic Information System (GIS) preprocessing was combined with the results of CROPWAT and Soil and Water Assessment Tool (SWAT) to estimate the reference evapotranspiration (ET 0), crop evapotranspiration (ET c), effective rainfall, runoff, recharge, and soil-moisture change. The available supply was estimated by using an addition of canal release, reservoir- operation values, ground water contribution, and contribution of return-flow. These findings indicate that irrigation takes up the largest portion of the annual water needs with about 98.4% of total yearly needs i.e. 1650 Mm³ of the total 1677 Mm³. The gross supply available was around 730 Mm³ which could only satisfy about 43.5% of the overall demand leaving behind an annual unfulfilled demand of around 947 Mm³, which would cater to almost 56.5% of the aggregate demand. The greatest demand was at April-May where it was approximately 197-212 Mm³/month, or 11.8-12.7% annual demand during this period. None of the months had over supply and highest monthly loss was in the months of March-May corresponding to a range of approximately 102-127 Mm³ monthly which only constituted about 10.8-13.4% of the annual loss in that year. The seasonal interpretation shows that the periods of water-stress are peak three months pre-monsoon and Rabi (spring) and Kharif (autumn) depend heavily on storage of the reservoir, efficient rainfall distribution, and timing of the canals. The results prove that annual supply volumes cannot be considered the only factors of KLIS performance, monthly alignment of crop-water demand and monsoon recharge with the performance of the storage and the canal delivery plays a vital role. The research offers application evidence on how to better reservoir rule curves, canal-sort, conjunctive ground water utilization, crop-arrangement and deficit-irrigation techniques in monsoon-based command regions that are semi-arid.