Reliability analysis of rainwater harvesting system for crop water supply in greenhouse

Abstract Climate change has an impact on the scarcity of sustainable water sources for plant water supply in a greenhouse. In the dry season, the availability of groundwater and surface water sources is insufficient to supply the crop water requirements. Adequate and consistent water supply is crucial to support the optimal growth and production of plants in a greenhouse. Rainwater harvesting can be an important alternative to mitigate water scarcity, reduce groundwater exploitation, and preserve environmental sustainability. This study investigates the reliability of rainwater harvesting from greenhouse roofs to supply the water demands of vegetable crops cultivated in the greenhouse surface area. The analysis was conducted based on rainfall depth values of a 20-year time series (2004-2023) from a representative rainfall station of the study area. The rainwater harvesting in the greenhouse can produce a capture volume of 25.43 m 3 (227.02 L/m 2 ) with a cumulative capture volume of 2116.72 m 3 and 20.07 m 3 (179.19 L/m 2 ) with a cumulative capture volume of 1643.82 m 3 , represents a mean monthly rainfall of 283.78 mm and a dependable rainfall with an 80% probability of 223.98 mm, respectively. The reliability of the rainwater harvesting system can fully supply the water needs of the vegetables-cucumber family, small vegetables, roots and tubers, and vegetables-solanum family, reaching 2.81 L/m 2 .day, 2.95 L/m 2 .day, 3.09 L/m 2 .day, and 3.23 L/m 2 .day, respectively. The average surplus of 18.91 m 3 was produced in the design based on the mean monthly rainfall depth and 13.55 m 3 in the dependable rainfall depth of 80% probability.