Generalized storage–reliability–yield relationships for rainwater harvesting systems

Abstract

Sizing storage for rainwater harvesting (RWH) systems is often a difficult design consideration, as the system must be designed specifically for the local rainfall pattern. We introduce a generally applicable method for estimating the required storage by using regional regression equations to account for climatic differences in the behavior of RWH systems across the entire continental United States. A series of simulations for 231 locations with continuous daily precipitation records enable the development of storage-reliability-yield (SRY) relations at four useful reliabilities, 0.8, 0.9, 0.95, and 0.98. Multivariate, log-linear regression results in storage equations that include demand, collection area and local precipitation statistics. The continental regression equations demonstrated excellent goodness-of-fit (R 2 0.96-0.99) using only two precipitation parameters, and fits improved when three geographic regions with more homogeneous rainfall characteristics were considered. The SRY models can be used to obtain a preliminary estimate of how large to build a storage tank almost anywhere in the United States based on desired yield and reliability, collection area, and local rainfall statistics. Our methodology could be extended to other regions of world, and the equations presented herein could be used to investigate how RWH systems would respond to changes in climatic variability. The resulting model may also prove useful in regional planning studies to evaluate the net benefits which result from the broad use of RWH to meet water supply requirements. We outline numerous other possible extensions to our work, which when taken together, illustrate the value of our initial generalized SRY model for RWH systems.

Generalized Storage–Yield–Reliability Relationships for Analysing Shopping Centre Rainwater Harvesting Systems

“…Acquiring detailed models may however not be free and applying them is likely to take more time than using simple generalized models. Generalized models are applicable for regional assessment of RWH potential [26] and may be preferred to detailed ones especially where time and other resources are scarce. Generalized RWH storage-yield-reliability relationships have been developed in other regions of the world [26][27][28] as regression equations of dimensionless ratios of the variables involved (with few exceptions).…”

Recent Advances in Modelling and Implementation of Rainwater Harvesting Systems towards Sustainable Development

“…In remote regions, RWH contributes towards meeting one of the targets of Sustainable Development Goals (ensuring availability and sustainable management of water and sanitation for all). In urban areas, the rainwater harvesting (RWH) system is generally used as an alternative water supply means for the non-potable purposes (e.g., toilet flushing, laundry, irrigation and car washing), and for control of stormwater [3,4]. The RWH system is also used as a water source for small scale agricultural needs in both urban and rural areas.…”

“…The RWH system is also used as a water source for small scale agricultural needs in both urban and rural areas. RWH is a primary water source in many rural areas and on islands [4]. Wider implementation of the RWH system can delay the construction of new water supply infrastructures such as dams and pipelines.…”

“…The modelling of the RWH system seeks to match the rainwater availability with the projected water demand [4,25]. This is generally undertaken by continuous simulation of the inflow and outflow [26][27][28] or using empirical relationships [4,29,30] or stochastic analysis [6,31] or a web-based tool that integrates geo-referenced rainfall patterns [32].…”

“…This is generally undertaken by continuous simulation of the inflow and outflow [26][27][28] or using empirical relationships [4,29,30] or stochastic analysis [6,31] or a web-based tool that integrates geo-referenced rainfall patterns [32]. RWH system is also analyzed as a stormwater management component [33][34][35].…”