Numerical Modelling of Drip Irrigation to Improve Water Use Efficiency in Semi-Arid Agroecosystems

In arid and semi-arid regions, the agriculture thrives on the use of irrigation systems such as drip and sprinkler irrigation which ensures the higher irrigation application efficiencies. However, the planning and design of drip irrigation systems continue to rely on generic understanding and manual hydraulic calculations which often leads to sub-optimal performance. The present study addresses this gap by using a numerical model for analysing the drip irrigation for Okra Cultivation in a semi-arid district of Udaipur, Rajasthan, India. Therefore, the objectives of this study are analysing the hydraulic performance of the given network of drip irrigation using a numerical model and evaluate its adequacy and operational efficiency.

The hydraulic adequacy is determined using EPANET 2.2 modelling tool employing pressure driven demand (PDD) approach. The temporal variability in the behaviour of system was captured by running the extended period simulation model. The model incorporates operational control rules to define the variable demands for the different phases of the growth of the plant and scheduling the pump and valve operations thereby enabling the digital twin of the drip irrigation system. The source of water taken as well is explicitly represented in the model while the filtration unit is represented as a non-return valve with high loss coefficient. In addition to the watering, the fertigation of the crops is also simulated in the model according to the fertigation schedule.

The hydraulic performance of the irrigation system is evaluated using standard performance indicators  such as the Coefficient of Uniformity, Coefficient of Variation, and Distribution Uniformity. Furthermore, the reliability of system performance is assessed using network reliability parameter.  Thus, the study will assist farmers and stakeholders in achieving optimal operation of drip irrigation systems by addressing and minimizing the multiple technical and operational challenges associated with this irrigation method.