Descriptive statical analysis of Rainwater potential at CST towards sustainable development

Urbanization, population growth, climate change, and oblivious human activities were exerting extreme pressure on urban water resources.Bhutan with substantial per capita water availability of 94,500 cubic meters experiences localized water scarcity, with only 63% of the population having 24-hour access to drinking water.This paper assessed the feasibility of the rainwater harvesting system (RWHS) implementation at the College of Science and Technology (CST) to alleviate the water shortages.The historical rainfall data from 1996 to 2023 reveal an average annual rainfall of approximately 4500 mm in the CST.An average building roof size of 1380.5 m 2 can harvest 5.2 million liters of rainwater annually.The common rainwater quality test parameters indicate temperature and total dissolved solids are within the permissible limits, with slight concern about pH and turbidity.Furthermore, the cost-benefit highlights the economic benefit of rooftop gravity rainwater harvesting system implementation.The proposed RWHS includes 3000 litre capacity HDPE tank mounted on a 9 m reinforced cement concrete (RCC) stand, costing approximately Nu. 0.26 million.The chosen building hosts around 360 students who consume 1224 Cu.m of water annually, the proposed RWHS could save Nu. 3 million over 50 years of structural lifespan by reducing the water bills.Additionally, the 5.2 Cu.m of rainwater harvesting potential could save another Nu.0.3 million each year.Overall, the study aims to provide a comprehensive analysis of rainwater potential at CST, evaluate per capita water consumption, and recommend effective RWHS with a cost-benefit analysis.