Optimal sizing of storage tanks in domestic rainwater harvesting systems: A linear programming approach

This paper proposes an optimization model to determine the optimal tank size of a single residential housing unit for rainwater harvesting and storage. Taking into account the site specific data such as the rainfall profile, the roof area of the building, the water consumption per capita and the number of residents, an integrated optimization model based on linear programming is proposed to decide on the size of rainwater storage tank to build such that the net present value of the total tank construction costs and freshwater purchase costs is minimized. The proposed model was tested on a case study from Northern Cyprus, the results of which emphasized the feasibility of rainwater harvesting as a sustainable supplement to the depleting aquifers in the region. The study also offers managerial insights on the impact of various parameters such as the number of residents, roof area, discount rate, water consumption per capita, unit cost of building the rainwater tank, and rainfall characteristics on the optimal tank size and on the net financial benefit gained from rainwater harvesting through detailed sensitivity analysis

Optimum tank size for a rainwater harvesting system: Case study for Northern Cyprus

The available freshwater is limited on earth. On the other hand, available water resources on earth have been depleting and being polluted due to climate change and population growth. In order to reduce the risk of water scarcity and water resources contamination, Integrated water resources management (IWRM) is required. IWRM is a concept to manage water resources that aims to balance economic efficiency, social equity, and environmental sustainability. When rainwater harvesting systems (RWHS), one of the techniques of IWRM, are implemented, the stress on water resources is reduced. Since the installation cost of rainwater harvesting systems significantly depends on the size of the rainwater storage tanks, in the implementation of rainwater harvesting, the selection of tank size is one of the main concerns for the feasibility of the system. This study aims to investigate the feasibility of domestic rainwater harvesting systems for a single house. In order to find the optimum storage tank size of the rainwater harvesting system, a linear programming (LP) optimization model is employed. As a case study, the LP model is applied to six regions from semi-arid Eastern Mediterranean island Northern Cyprus, where water resources are limited. The model considers thirty-seven years monthly rainfall data, the roof area of the building, the water consumption per capita, the discount rate, the cost of the rainwater storage tank, and the number of residents. The results of the selected study areas show that the implementation of the RWHS for a single house is infeasible due to the substantial installation costs and maintenance expenses. The financial losses caused by the implementation of the RWHS are found higher than the installation costs and maintenance expenses for all regions. In addition to economic analyses, environmental benefits of the RWHS should be included into the feasibility analysis

Rainwater Harvesting System for Dormitories of METU - Northern Cyprus Campus

Water scarcity in the Mediterranean islands has become an important issue to be addressed due to inadequate water supplies and low precipitation in the region. Rainwater harvesting system (RWHS) is one of the promising solutions to overcome the water shortage which not only conserves water resources but also reduces the overall carbon foot print of water collection and distribution cycle. This paper presents the theoretical potential of rainfall in Northern Cyprus for constructing a Rainwater Harvesting System for the dormitories of Middle East Technical University – Northern Cyprus Campus. Instead of introducing RWHS in each of the three dormitories ineffectively, it is found to be realistic for non-potable uses in only one dormitory with an overall collected volume of 2831 m3 and a volumetric reliability of ~93%. The results of this study provide an opportunity for water scarce regions to use their limited resources in an efficient manner