THE BLIND ANGLE: PERFORMANCE ASSESSMENT OF DRIP IRRIGATION IN USE IN A LARGE-SCALE IRRIGATION SCHEME IN MOROCCO

The need for lasting returns on the large investment in state-sponsored drip irrigation projects and the ambitious objectives aimed to achieve requires thorough and continuous assessment of the performance of irrigation systems in use. However, few studies have evaluated the performance of systems once they have been installed, leading to overestimation of actual drip irrigation performance. This study focuses on the Tadla Irrigation Scheme, where a 10 000-ha drip irrigation project had two objectives: improving water productivity and reducing pressure on groundwater resources. The results of the study show a satisfactory but progressively declining distribution uniformity at field level, after 3-4 years of functioning, pointing to potential dysfunction if the equipment is not renewed. The current over-irrigation of crops results in hefty water bills and debts of farmers, no water savings at the field scale, some savings at the scheme scale, but increased tension concerning water delivery. Farmers continued to use groundwater after converting to drip irrigation to avoid surface water shortage. The challenge is to ensure that groundwater is only tapped in exceptional cases to avoid overexploitation. The first step is ensuring more efficient irrigation practices, underlining the need for continuous performance assessment. (c) 2019 John Wiley & Sons, Ltd. (c) 2019 John Wiley & Sons, Ltd.