Irrigation Performance Indicators for Best Irrigation Management in an Irrigation District

Irrigation water management in the Genil-Cabra irrigation district, located in the province of Cordoba, southern Spain, was studied using three irrigation performance indicators: relative irrigation supply (RIS); relative water supply (RWS) and relative rainfall supply (RRS). All indicators have been calculated as in a global way as grouping data according to crop type, irrigation method and soil texture. All information of agronomic and hydraulic variables was incorporated in a Geographic Information System (GIS) to ease its management. Results show that applied irrigations are deficit irrigations because RIS values are relatively low. However, RWS values are greater and evaporative demand may be satisfied along crop development cycle. RRS indicator varies less than the other two and, together with RWS, permits to know the evapotranspiration fraction covers by rain water. Irrigation water management in four crops (olive, cotton, sunflower and maize) is considered to be adequate. In the case of sugar beet and asparagus, the deficit is larger. Wheat and garlic are the two crops that show inefficient management due to an excess supply of water. RWS and RIS values are higher for sprinkler irrigation than for drip irrigation. Soil type has little influence on irrigation management. In general, more water is applied to crops planted in sandy loam soils than in silty clay loam soils. The mean values of performance indicators we have calculated are very useful to know farmer's behaviour and the general trend, although the used sample is not significant to characterize the global irrigation district.