Analysis of climate scenarios and effects on water availability for irrigation in Río Dulce irrigation system, Santiago del Estero, Argentina

Abstract

Climatic change has already altered hydrological cycles and will undoubtedly alter availability of water for irrigation during the coming decades. The objective of this study was to quantify future water balance andavailability of water for irrigation under different climate change scenarios in the upper Salí-Dulce watershed located in northern Argentina. This basin is home to one of the most important irrigation systems in Latin Americaactually covering about 82000 hectares located entirely in Santiago del Estero province. In order to generate tools for sustainable agricultural development, future analysis of water balance and water availability for irrigation, theSWAT model was used and linked with projections from nine models that participated in the Coupled Model Intercomparison Project Phase 5 (CMIP5) and downscaled to Salí-Dulce catchment. The simulation was carried out for four futuristic periods: P1(2020?2039), P2 (2040?2059), P3 (2060?2079) and P4 (2080-2099) under two Representative Concentration Pathways RCP 4.5 and RCP 8.5 and was contrasted with a baseline scenario simulated for a period of 50 years (1968-2017) on a monthly scale. Monthly model calibration approaches gavegood results based on a statistical fit with Nash Sutcliffe Efficiency (NSE) and Coefficient of Determination (R2) of 0.7 and 0.71 for calibration period (1988?1999), and 0.68 and 0.69 for validation period (2000-2008), respectively. The CC projections show an increasing trend in precipitation and discharge throughout the basin of 8% and 11% and an increasing trend in ET of 12 and 14% for both CC pathways respectively (RCPs 4.5 and 8.5) throughout the basin. Outcomes of this study give insight on future evapotranspiration, water balances andavailability of water for irrigation and possibility to increase irrigated area to system potential of 120000 hectares. It is also an important tool during the decision-taking process to sustainably develop this watershed´s irrigation system taking into account all different interests of all involved actors and by this means assure productivity for future generations.