An integrated approach for the assessment of water availability for irrigation in semi-arid regions

摘要

An integrated approach to water availability assessment for irrigation is presented and illustrated through examples from Canada's South Saskatchewan River Basin (SSRB). It is based on the integration of irrigation and non-irrigation water demands at the basin level, and accounts for the seasonal and annual variation in water supply and water demand. Irrigation water demands are derived from a detailed simulation model which estimates irrigation water diversion and return flow based on physical, climatic and operational parameters and management practices. By integrating the time varying demand and supply, water availability can be expressed in terms of probability or a risk-management context. The impact of any long-term climatic changes on water availability is determined through integration of the resulting changes in water demand and water supply. The paper explains the modelling framework used and its application to SSRB, with special emphasis on irrigation. The importance of accounting for the temporal variability of demand and supply when assessing water availability is demonstrated through several examples, including sensitivity analysis of the irrigation sector and the overall basin water resources to climatic changes. The views expressed in this paper are those of the authors and do not necessarily represent the views of their employer.