Modelling of smart irrigation with replan and redistribution algorithms
Climate change is strongly aﬀecting the availability of water. The demands of water in agriculture are by far the largest, where 70% of the water used in Portugal, is used in agriculture, and, from that 40% are lost due to inefficiency. To develop intelligent irrigation systems to save water is a priority. Current irrigation systems mostly have a controller of the ON-OFF type. The irrigation with ON-OFF controllers might experience limitations, especially when the crop water needs are small and sampling periods are large. Using optimal control formulations and techniques, the water consumption can be made to follow more closely the hydrological needs of the crop, while also taking into account current weather conditions. In this paper, the mathematical model presented by the authors in previous publications is improved. This new model incorporates new features like the slope of the soil, the possibility to include a percentage of water losses due to runoff, and a percentage of water losses if the soil is on the field capacity. A new and more efficient replan strategy is applied tacking into account the data measured from moisture sensors, to ensure that hydric needs of the crop is fulfilled. A new approach to deal with multiple irrigation points is also proposed. It allows to redistribute the available water in the case an irrigation point is not able to provide the water needed, accordingly to its irrigation plan.