Long-term Changes of Irrigation Water Requirement in the Context of Climatic Variability

Abstract

The knowledge of exact amount of water required by different crops in a given set of climatological condition of a region is vital in planning and effective management of irrigation scheme, irrigation scheduling and so on. This paper proposes the effect of different climatological variables on reference evapotranspiration (ETo) and water uses in agriculture in the Seonath basin located in Chhattisgarh State. The study area has 24 meteorological stations. Results of analysis of annual temperature time series showed a rise of 0.9702 °C over a period of 51 years (1960–2010). The increasing trends in ETo were more pronounced. Annual analysis of the ETo series indicated an increasing trend in almost all the districts except Bilaspur district. The percentage change in annual ETo was maximum for Raipur (1.72%) and minimum for Bilaspur (–1.41%). The analysis of the impacts of meteorological variables on the trends of ETo revealed that the main driving force associated with the increasing trend of ETo in the Seonath river basin was temperature and relative humidity. Overall, the results of this study showed an increase in irrigation water requirement, because of projected increase/change in meteorological variables (viz., rainfall, Tmax and Tmin, relative humidity and wind speed). Therefore, changing irrigation demand appraisals presented in this paper would be useful for future irrigation management systems for the Seonath river basin.