Determination of rainwater harvesting potential and storage capacities in greenhouses in the Marmara region

Greenhouses are agricultural structures that allow plant production regardless of seasonal conditions. In field crop production, irrigation is used to meet plant water needs that cannot be met by natural rainfall, whereas greenhouses can only meet these needs through irrigation. This study aims to determine the rainwater harvesting potential of plastic-covered greenhouse roof systems in the Marmara Region, encompassing both developed and developing provinces in Türkiye where greenhouse cultivation is widespread. This potential was used to determine whether this potential could meet the greenhouse irrigation needs and to calculate the optimal storage capacity. Tomatoes, commonly cultivated in greenhouses, were used as a reference for plant production, and plant water requirements were determined. Considering that greenhouse production takes place in months other than July and August, it has been determined that, although the period varies across all provinces in the region, rainwater harvesting can meet greenhouse irrigation needs. In the study, appropriate storage capacities were determined for design based on plant water consumption and rainfall. Storage tank volumes were 0.1 m3 in Balıkesir, 0.1 m3.m-2 in Bilecik, 0.2 m3.m-2 in Bursa, 0.15 m3.m-2 in Edirne, 0.26 m3.m-2 in Kocaeli, 0.10 m3.m-2 in Kırklareli, 0.25 m3.m-2 in Sakarya, 0.10 m3.m-2 in Tekirdağ, 0.12 m3.m-2 in Yalova, 0.15 m3.m-2 in Çanakkale, and 0.16 m3.m-2 in Istanbul. In this context, the study provides detailed information for greenhouse designers, public institutions, and organizations regarding new projects on water harvesting and agricultural production planning, and new studies that will contribute to future water management policies.