Generalized Equations for Potential Water Savings from Rainwater Tanks in Adelaide under Different Climates

Upendra Paudel,Monzur A Imteaz

doi:10.1051/matecconf/20165404004

Abstract

With ever-increasing water demand, authorities around the world are considering different options including water recycling and rainwater harvesting to minimize potable water demand. Among all the alternative options, rainwater harvesting system is the most feasible to minimize potable water demand, This paper presents development of generalised equations for the quantifications of potential water savings under different climatic conditions for an Australian city, Adelaide. An earlier developed daily water balance model, eTank, which can calculate potential water savings in three climatic conditions (dry, average and wet) was used for this purpose. Several relationship graphs of water savings were produced through model calculations for different input parameters, i.e. roof area, tank volume and rainwater demand for each climatic condition. From the produced graphs, three (one for each climatic condition) generalised equations were developed, where water savings were presented as a function of roof area, demand and tank volume. Results from the developed equations were compared with model calculated results under different conditions and it is found that results from the generalised equations are very close to the model calculated results. Such equations are expected to be very helpful for general end users and will encourage them for implementing rainwater harvesting with prior knowledge.

Highlights

Water shortage is a major problem in many parts of the world
Imteaz et al [15] introduced a factor, Rainwater Accumulation Potential (RAP), which is a ratio of roof area and water demand; and using eTank presented relationships of RAP with rainwater reliability under different climatic conditions for Melbourne city. Incorporating another factor to earlier proposed RAP, this paper presents a modified form of Rainwater Accumulation Potential (RAP), which is the ratio of water demand to roof area multiplied by tank volume and shows relationships of modified RAP with annual savings under different climatic conditions for Adelaide
Water balance model was simulated with the daily rainfall data for the above-mentioned years to evaluate the annual water savings for different tank sizes (2500L, 5000L, 7500L and 10,000L) with roof area ranges from 100~300 m2 and demand from 200 to 500 L/day

Summary

Introduction

Water shortage is a major problem in many parts of the world. Regions which depend on groundwater, due to over-extraction ground water table dropping down significantly. Due to the impacts of climate change some parts of the world are experiencing less amount of rainfall than average rainfall. As such it is imperative for the scientist, water supply engineers, policy makers and government authorities to think on the reliability and sustainability of the town water supply which is mostly rely on ground/surface water. To reduce the over extraction of ground water and cope with climate change, different stakeholders are emphasizing to use stormwater harvesting systems as one of the alternative options. Among all the stormwater harvesting systems, rainwater harvesting system is getting much more attention because it is easy to harvest and needs lesser or minimal treatment for laundry, toilet flushing and outdoor uses

Methods

Results

Conclusion