Probability and Consequence of Postfire Erosion for Treatability of Water in an Unfiltered Supply System
Details
Serval ID
serval:BIB_FA428F1FB11F
Type
Article: article from journal or magazin.
Collection
Publications
Institution
Title
Probability and Consequence of Postfire Erosion for Treatability of Water in an Unfiltered Supply System
Journal
Water Resources Research
ISSN
0043-1397
1944-7973
1944-7973
Publication state
Published
Issued date
01/2021
Peer-reviewed
Oui
Volume
57
Number
1
Language
english
Abstract
Forested catchments are critical to water supply in major cities. Many of these catchments face the threat of postwildfire erosion, which can contaminate reservoir water. The aim of this paper is to determine the probability and duration of disruptions to treatability due to runoff-generated debris flows in the first year after a wildfire, before substantial vegetation recovery takes place. We combine models of reservoir hydrodynamics, postfire erosion, and stochastic rainfall to determine probability and magnitude of sediment concentration at the reservoir water offtake. Central to the paper is our technique for linking model components into a risk framework that gives probabilities to the number of days that the turbidity threshold for treatment is exceeded. The model is applied to the Upper Yarra reservoir, which is the linchpin of the water supply system for Melbourne in SE Australia. However, the framework is applicable to other unfiltered water supply systems where suspended sediment is a risk to treatability. Results show that postwildfire erosion poses a substantial threat, with a relatively high probability (annual exceedance probability = 0.1–0.3) of water being untreatable for >1 year following a high-severity wildfire. Important factors that influence the risk include postwildfire runoff potential, reservoir temperature, and the amount of clay-sized grains in eroding headwaters. Assumptions about spatial-temporal rainfall attributes, reservoir hydrodynamics, and the catchment erosion potential are all important sources of error in our estimate of risk. Our approach to risk quantification will help support planning, risk management, and strategic investment to mitigate impacts.
Keywords
Water Science and Technology
Web of science
Create date
09/08/2021 15:02
Last modification date
15/11/2022 15:05