Climate-induced shifts in irrigation water demand and supply during sensitive crop growth phases in South Asia

• Published in: Climatic change Vol. 176; no. 11; p. 150
• Main Authors: Ahmad, Qurat-ul-Ain, Moors, Eddy, Biemans, Hester, Shaheen, Nuzba, Masih, Ilyas, ur Rahman Hashmi, Muhammad Zia
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01.11.2023; Springer Nature B.V
• Subjects: Assessments; Atmospheric Sciences; Cereal crops; Climate change; Climate Change/Climate Change Impacts; Climate models; Crop growth; Crop management; Crop water; Crops; Earth and Environmental Science; Earth Sciences; Economic development; Economics; Environmental impact; Global climate; Global climate models; Groundwater; Groundwater irrigation; Growing season; High temperature; Hydrology; Impact assessment; Irrigation; Irrigation water; Phases; Planting; Precipitation; Regional analysis; Rice; River basins; Socioeconomic aspects; Socioeconomics; Surface water; Surface-groundwater relations; Temperature effects; Temperature rise; Trend analysis; Vegetation; Water consumption; Water demand; Water management; Water use; Wheat; South Asia; Crop water demand; Climate change; Groundwater irrigation; Phenology; Crop growth phases
• ISSN: 0165-0009; 1573-1480
• DOI: 10.1007/s10584-023-03629-7

This study investigated the shifts in irrigation water demand and supply of the major staple and water-intensive crops (wheat and rice) in the Indus, Ganges and Brahmaputra (IGB) river basins of South Asia under the combined impacts of climate change and socio-economic development during the period 1981–2100. It explores irrigation water usage during climate-sensitive crop growth phases (i.e. vegetative and reproductive which required ~ 60% of the total seasonal (sowing to harvest) water demand), which is supposed to be crucial for long-term integrated crop water management. A hydrology vegetation model Lund Potsdam Jena Managed Land is forced with an ensemble of eight downscaled (5 arc-min) global climate model’s using the RCP (Representative concentration pathways) -SSP (Shared socio-economic pathways) framework, i.e. RCP4.5-SSP1 and RCP8.5-SSP3. To investigate phase-specific crop water projections, trend analysis is performed. It shows a significant ( p <0.001) increase in irrigation water demand during the vegetative phase of wheat (6 mm) and reproductive phase of rice (26 mm) and a decrease during the reproductive phase of wheat (13 mm) and vegetative phase of rice (11 mm) in selected study sites. The large decrease in projected irrigation demand for wheat can be explained by a shortening of the growing season length as a result of rising temperatures and increased precipitation. Whereas, an increase in irrigation demand for rice is a combined effect of higher temperatures and less precipitation during the reproductive phase in the region. At the same time, irrigation supply by surface water and groundwater is likely to change in future due to warmer and drier growing periods, causing a significant increase in groundwater irrigation, mainly for rice. Our major research findings show the importance of crop water assessments during the sensitive crop growth phases of wheat and rice which vary in space and time. Including crop phase-specific, climate impact assessments of regional and global projection will help improve the region’s existing crop-water management strategies and adaptation practices.