Search

[Display omitted] • Wildfires are becoming more severe and frequent and their effects increasingly expose water resources to stress. • Climate, wildfire, streamflow records (1975 to 2018), topography, and landcover data from 92 catchments were combined to quantify the contribution of wildfire to streamflow variability across Australian temperate forests. • On average wildfire regimes relatively results in 8.8% increases in streamflow across Australian temperate forests. • Wildfire effects on regional streamflow varied spatially depending on hydroclimate factors, particularly precipitation. As wildfires become more frequent and severe, there are concerns regarding their impacts on water yield from forested catchments. While there are many studies in Australia about the effects of individual wildfires on streamflow at fine scales (<1 km2) in specific geographic settings, the effects of wildfire regimes on streamflow at broad spatial scales across temperate forests in Australia are not well understood. In this paper, we combined climate, wildfire, streamflow records (1975 to 2018), topographic, and landcover data from 92 catchments (74 – 4740 km2) in the Australian temperate zone to quantify the contribution of wildfire regimes over time to streamflow variability in different hydroclimatic settings (humid, dry sub-humid, and semi-arid) and geographic regions (Southeast Australia (SEA), Southwest Western Australia (SWWA), and Tasmania (TAS)). Wildfire regimes were represented by two metrics: the burnt area to drainage area (BDA) ratio for wildfire events in each year and a spatially averaged metric of Time Since Fire (TSF), which is a spatial average of time since the last wildfire in the catchment. By comparing prefire and postfire runoff ratios our study found that on average there was a short-term increase in runoff ratio (∼3% in year 1 and ∼6% in year 2 post-fire) after wildfires with BDA > 25%. No influence of fire was found in the long-term (15–20 years after the wildfire) runoff ratio. We found that wildfire regime, measured by TSF, explained ∼8.8% of the variation in annual streamflow across the Australian temperate zone, and that with decreasing TSF (i.e., increased wildfire impact), the average streamflow increased. Streamflow variation explained by wildfire regimes varied with hydroclimate. The explained variance of streamflow by wildfire regimes in semi-arid catchments (23%) and dry sub-humid catchments (13%) were higher than humid catchments (5%). Our results provide a broad-scale understanding of how wildfire regimes influence streamflow variability at broad temporal and spatial scales, and provided important context and baseline information for determining the implications of changes in climate and fire regimes for regional water availability. [ABSTRACT FROM AUTHOR]

As the evidence for human induced climate change becomes clearer, so too does the realization that its effects will have impacts on numerous environmental and socio-economic systems. Mountains are recognized as very sensitive physical environments with populations whose histories and current social positions often strain their capacity to accommodate intense and rapid changes to their resource base. It is thus essential to assess the impacts of a changing climate, focusing on the quantity of water originating in mountain regions, particularly where snow and ice melt represent a large streamflow component as well as a local resource in terms of freshwater supply, hydropower generation, or irrigation. Increasing evidence of glacier retreat, permafrost degradation and reduced mountain snowpack has been observed in many regions, thereby suggesting that climate change may seriously affect streamflow regimes. These changes could in turn threaten the availability of water resources for many environmental and economic systems, and exacerbate a range of natural hazards that would compound these impacts. As a consequence, socio-economic structures of downstream living populations would be also impacted, calling for better preparedness and strategies to avoid conflicts of interest between water-dependent economic actors. This paper is thus an introduction to the Special Issue of this journal dedicated to the European Union Seventh Framework Program (EU-FP7) project ACQWA (Assessing Climate Impacts on the Quantity and Quality of WAter), a major European network of scientists that was coordinated by the University of Geneva from 2008 to 2014. The goal of ACQWA has been to address a number of these issues and propose a range of solutions for adaptation to change and to help improve water governance in regions where quantity, seasonality, and perhaps quality of water may substantially change in coming decades. [ABSTRACT FROM AUTHOR]

• The water supply system of interest includes a river network, dam and water treatment plant. • Evaluated the effect of climate change impacts on water quality (in particular TOC). • Variations of TOC in the system under three climate change scenarios have been simulated. • Level of adaptation capacity of water treatment plant has been analyzed. • Climate change influenced the water supply system and the acute adaptation plan is recommended. Evaluation of the impact of climate change on water sectors is one of the most important challenges of water resources management in the current century. In this paper, assessment of vulnerability to climate change on total organic carbon (TOC) concentration in the Jajrood catchment in Tehran has been done. The hydroclimatologic parts of the assessment have been done by implementing HYMOD and downscaling of precipitation, temperature and evaporation using statistical downscaling model (SDSM). Three climate change scenarios (RCP 2.6, RCP 4.5 and RCP 8.5) from the Canadian Earth System Model have been used to project climate change (2006 to 2050). Moreover, different linear models were used to model water quality in Latyan Dam and Tehranpars Water Treatment Plant (TWTP). Based on the results, the average annual simulated rainfall under RCP 2.6, RCP 4.5, and RCP 8.5 are 670.2, 658.06 and 650.93 mm, respectively. The projected streamflow under the scenarios were 97%, 90%, and 92%, respectively, more than observation period. The average simulated TOC concentration in influent water was 52.43 (mg/L), which was about seven times more than the averaged observed value (8.78 mg/L). The most important byproduct of the current impact assessment is to define an adaptation action plan, because the TWTP will not be able to provide drinking water standards in this area. [ABSTRACT FROM AUTHOR]