Intelligent urban irrigation systems: Saving water and maintaining crop yields

Intelligent irrigation is one sustainable solution to reduce demands on water resources and adverse environmental impacts from irrigation. Specific case studies have quantified water savings with intelligent irrigation, however, water savings have not yet been quantified for urban agriculture or compared across climates. Before urban agriculture implements intelligent irrigation, requiring an added cost and knowledge requirements of the control system, the effects of the system must first be estimated for a broad range of climatic conditions. We hypothesized that an intelligent irrigation system will decrease water use without reducing crop yield. With CROPWAT, we modeled an urban tomato garden irrigated conventionally to one irrigated intelligently in each of the nine climatic regions of the United States. Tomatoes were selected because they are sensitive to water stress. The intelligent irrigation system included a wireless sensor network and controllable valves. In addition, we created the Conventional-Scenario Intelligent-Scenario Index to compare the overall performance of an intelligent irrigation strategy to a conventional one. Our simulations showed that the intelligent irrigation scenario decreased water use on average by 59% in all sub-humid climates while maintaining yield (0% reduction). All sub-humid climates (7 of 9 total zones) fell within the “fair” to “good” index categories. Based on these results, urban agricultural sites should consider installing intelligent irrigation systems if they are in sub-humid climates. In the two semi-arid climates, our intelligent irrigation scenario eliminated the 6–10% crop yield reductions of the conventional scenario but did not reduce water consumption. Both locations fell within the “fair” index category. The minor improvements in the semi-arid climates may not outweigh the added system costs.