Urban Water Mass Balance Analysis

Abstract

Planning for "water-sensitive" cities has become a priority for sustainable urban development in Australia. There has been little quantification of the term, however. Furthermore, the water balance of most cities is not well known. Following prolonged drought, there has also been a growing need to make Australian cities more water self-reliant: to source water from within. This article formalizes a systematic mass-balance framework to quantify all anthropogenic and natural flows into and out of the urban environment. Quantitative performance indicators are derived, including (1) degree of system centralization;(2) overall balance; potential of (3) rainfall, (4) stormwater, and (5) wastewater to offset current demand; and (6) water cycle rate. Using the method, we evaluate Sydney, Melbourne, South East Queensland and Perth using reported and modeled data. The approach makes visible large flows of water that have previously been unaccounted and ignored. It also highlights significant intercity variation. In 2004-2005, the cities varied 54% to 100% in their supply centralization, 257% to 397% in the ratio of rainfall and water use, 47% to 104% in their potential stormwater recycling potential, and 26% to 86% in wastewater recycling potential. The approach provides a practical, water-focused application of the urban metabolism framework. It demonstrates how the principles of mass balance can help foster robust water accounting, monitoring, and management. More important, it contributes to the design and quantitative assessment of water-sensitive cities of the future.

Efficiency of stormwater control measures for combined sewer retrofitting under varying rain conditions: Quantifying the Three Points Approach (3PA)

“…In our study we focused on the rainfall above a defined 112 municipal area and the engineered flows (stormwater runoff, supply of potable water 113 and wastewater flow directed to the wastewater treatment plant) as these together pose 114 the greatest cost to society (Kenway et al, 2011 includes all events with T>10 years, but in order to constrain the domain and quantify 180 the point explicitly we chose a return period of 100 years, which is a commonly used 181 design criterion. 182…”

A metabolism perspective on alternative urban water servicing options using water mass balance

“…The water metabolism evaluation framework (Figure 1) developed for this work has at its core an 127 urban water mass balance, based on a method described by Kenway et al (2011a). The water 128 mass balance quantifies all natural and anthropogenic flows and fluxes of water through a defined 129 urban area.…”

“…Applications of urban water metabolism evaluation to date have mostly examined and compared 101 potable water use among cities and over time (Kennedy et al 2007, Kennedy et al 2015), to 102 highlight the underutilization of available water sources (Kenway et al 2011a), or quantify the 103 degree to which urbanisation influences natural hydrological flows (Haase 2009). We extend its 104 use to evaluating water servicing options.…”

Concepts and Methodologies for Measuring the Sustainability of Cities

“…Traditionally, UM studies focused largely on the processes that sustain cities and not on the impacts that cities cause on distant or global processes (103,104). There is a value in this, as resources such as water, or outgoing waste flows, often retain strong links to the areas surrounding cities and self-reliance can be of high policy priority (90). An understanding of the relationship between a city and its hinterland -or historical "supplying" area -can be achieved through a territorial approach.…”

“…The remaining literature predominantly takes one particular material or flow as a focus for analysis. This includes, for example, urban water balances (89,90). Moreover a significant body of studies that quantify the energy use and/or GHG emissions of cities, as covered in section 3, use an MFA framework.…”