Effects of Climate Temperature and Evapotranspiration and Irrigation Demand

Abstract

Global warming and rising evapotranspiration rates are straining freshwater resources and irrigation systems, especially agricultural irrigation systems. Understanding the correlation between global temperature, ET₀, and irrigation water demand is crucial for managing water resources and ensuring food security during climate change. The meteorological departments, agricultural databases, and FAO AQUASTAT provided secondary time-series data for wheat, maize, cotton, and vegetable crops from 2009 to 2023 for this quantitative analysis. The FAO-56 Penman-Monteith equation, the international standard for reference ET, calculated ET0. To assess the link between temperature, ET₀, and irrigation demand for various crops, statistical procedures such descriptive statistics, Pearson correlation analysis, multiple regression, and seasonal decomposition were used. The multiple regression model predicts irrigation demand with a R² = 0.891 (p < 0.001), with ET₀ (standardised β = 0.643) and Maximum temperature (β = 0.312) contributing most. Summer (June–August) had 47.3% of the year's irrigation water demand, 5.5 times more than winter. Cotton needed the most irrigation water (280 mm/summer) and wheat the least (195 mm). The results show that under projected warming scenarios, agricultural water plans should account for a 4.2% increase in irrigation water demand for crops per 1°C increase in mean temperature.