CONSTRAINING RAINWATER HARVESTING POTENTIAL AT NUST USING COMPUTATIONAL APPROACH

Abstract

Pakistan is one of the 36 most water stressed countries, which may be attributed to factors such as rapid population growth, unplanned urbanization, unregulated industrialization, increased agricultural activities, mismanagement and unjust distribution and contamination of water resources. This calls for exploration of sustainable water resources. Our project falls under the goal 6: Clean water and sanitation for all, of Sustainable Development Goals by United Nations. This project aims to explore potential of roof rainwater harvesting system at NUST due to its relatively good quality and simple maintenance. A time-series analysis was conducted to account for the variation and distribution of rainfall in Islamabad. The Tangki National Hydraulic Research Institute of Malaysia (NAHRIM) model was used to carry out 105 simulations on three usage scenarios based on the expected quality of harvested water. Turbidity, alkalinity, pH, hardness, microbiological contamination, heavy metal, and phenolic compounds were considered in assessment of roof rainwater quality at NUST. Islamabad experiences most rainfall in July and August and highest variation was also observed during these months. Irrigation usage scenario required the minimum treatment. The potable water scenario gave maximum water-saving efficiency for all buildings in the range of 1 to 30 cubic meters of tank capacity. Total Demand and Non-potable demand resulted in higher storage efficiency for all buildings considered. Around 90 percent tank capacities were in range 25-30 m3 at maximum water saving efficiency. The Press Building of NUST achieved the maximum water saving efficiency of 95 percent in case of potable demand scenario. A detailed excel database was also created for optimization of tank size for 35 buildings in NUST. A total of 36,290 cubic meters of water can be saved per year if tanks are built on maximum water-saving efficiency criteria, which accounts for 2.73 % of total demand at NUST.