Evaluation of a hypothetical suppression scenario of the spate irrigation system in Coeneo-Huaniqueo, Michoacán, Mexico

Introduction: There is a traditional irrigation system in Mexico called entarquinamiento (spate irrigation), which falls into the flood irrigation category, also known as cajas de agua (literally water boxes). Certain effects generated by traditional irrigation systems are intentional and others not entirely. Objective: To demonstrate that spate irrigation systems generate unintended effects such as flood control, in a 100-year return period, in the presence of maximum floods. Methodology: A hydrological analysis was carried out for two scenarios: 1) current situation (water boxes operating) and 2) hypothetical situation (boxes for this purpose are suppressed or disused). Within the hydrological model, with the HEC-HMS program, the methodologies of the Soil Conservation Service (SCS) of the United States (runoff curve number and unit hydrograph) and a design storm of 167.8 mm were considered. Flood routing in channels was performed using the Muskingum method. Results: With the current situation, the flow rate generated at the box system outlet was 0 m·s, which is the product of the partial storage of the runoff, while with the hypothetical situation, the maximum flow rate becomes 535.5 m·s. Study limitations: The efficiency of the water box system as an irrigation technique was not evaluated. Originality: There are few hydrological studies that demonstrate quantitative benefits of traditional irrigation techniques. Conclusions: The operating water box system functions as a reservoir. If the boxes were removed, a runoff would be generated that would flood agricultural and urban areas.