Irrigation potential of the TRASVASE system (Santa Elena Peninsula, Guayas, Ecuador)

The objective of this study was to determine the total irrigable area in the Santa Elena Peninsula Water Delivery System (TRASVASE) under several land use scenarios based on a simple water budget model requiring estimation of: (1) crop water requirements (CWR); (2) irrigation efficiency; and (3) dams and canals evaporation utilizing weather data. CROPWAT, a software package developed by the United Nations Food and Agriculture Organization (FAO), was used to calculate CWR and irrigation requirements. The reference evapotranspiration (ET0) was calculated using Santa Elena Peninsula historical average weather data and results used to create average monthly ET0 surface maps using ArcMap. Nine scenarios were created to calculate available agricultural water and irrigable area. The total calculated irrigable area during the dry season (June-November) was compared to estimate from the Commission for the Development of the Guayas River Basin in Ecuador (CEDEGE) and to the average estimate done by the farmers. CEDEGE estimate was 23,000 ha, 48% more than the most water conservative scenario (CB) analyzed in this study, whereas farmers' projected average was 16,500 ha or 0.06% more. The advantage of this method is that it requires minimal climatic and geographic information coupled with well-established FAO models to produce tangible results. It can be of important use in locations where climatic data is limited, reducing dependency on weather stations to calculate system wide irrigation requirements.