44 research outputs found
Changes in Drought Characteristics and Heatwave Propagation Over Groundwater Basins in Australia
No full textThe commitment to reduce emissions in global climate change science meetings shows collective responsibility to mitigate the risk of climatic extremes in the Anthropocene. However, growing anthropogenic footprint and climate change will exacerbate the impacts of extreme events on freshwater systems, necessitating the need to enhance contemporary understanding of future changes in drought characteristics (e.g., severity, duration, etc.) and climatic extremes in groundwater basins to assess their implications for water supplies and allocation. Using bias-corrected ensemble mean of nine Coupled Model Intercomparison Project Phase 6 (CMIP6) models, drought characteristics are assessed for two future socio-economic scenarios (SSP 370 and 585). Two drought indicators (standardised precipitation index and standardised runoff index) were combined with Heatwave total length (HWTL) to measure changes in drought characteristics and heatwave propagation, respectively, over four groundwater basins (South West Western Australia-SWWA; Murray Darling Basin-MDB; Cambrian Limestone Aquifer-CLA; and South Australia-SA) in Australia. Our findings indicate that as Australian summers become considerably warmer, particularly toward the late twenty-first century, the relationship between rainfall and runoff extremes, which exhibited strong connections historically (e.g., in CLA; r = 0.87), will vary in the future. This relationship is expected to increase in SA, showing stronger correlations (r = 0.67 and 0.82 for SSP 370 and SSP 585, respectively) but decrease in SWWA (r = 0.43 and 0.20, for SSP 370 and SSP 585, respectively). In the MDB, heatwaves are projected to propagate more rapidly into hydrological drought during summer and autumn under the SSP 585 scenario. Even though drought-affected areas are expected to decline in between decades across Australia, the duration and intensity in some locations show no signs of reduction. Increasing drought duration and intensity could limit freshwater availability, and such impact can potentially be exacerbated by the observed shifts and considerable changes in the propagation time of meteorological drought and HTWL to hydrological drought in some basins.Full Tex
Global vegetation, moisture, thermal and climate interactions intensify compound extreme events
No full textCompound extreme events, encompassing drought, vegetation stress, wildfire severity, and heatwave intensity (CDVWHS), pose significant threats to societal, environmental, and health systems. Understanding the intricate relationships governing CDVWHS evolution and their interaction with climate teleconnections is crucial for effective climate adaptation strategies. This study leverages remote sensing, reanalysis data, and climate models to analyze CDVWHS during historical (1982–2014), near-future (2028–2060), and far-future (2068–2100) periods under two Shared Socioeconomic Pathways (SSP; 245 and 585). Our results show that reduced vegetation health, unfavorable temperature conditions, and low moisture conditions have negligible effects on vegetation density. However, they worsen the intensity of heatwaves and increase the risk of wildfires. Wildfires can persist when thermal conditions are poor despite favorable moisture levels. For example, despite adequate moisture availability, we link the 2012 Siberian wildfire in the Ob basin to anomalous negative thermal conditions and concurrent unfavorable thermal-moisture conditions. In contrast, the Amazon experiences extreme and exceptional drought associated with unfavorable moisture conditions in the same year. A comparative analysis of Siberian and North American fires reveals distinct burned area anomalies due to variations in vegetation density and wildfire fuel. The North American fires have lower positive anomalies in burned areas because of negative anomalous vegetation density, which reduced the amount of wildfire fuel. Furthermore, we examine basin-specific variability in climate teleconnections related to compound CDVWHS, revealing the primary modes of variability and evolution of CDVWHS through climate teleconnection patterns. Moreover, a substantial increase in the magnitude of heatwave severity emerges between the near and far future under SSP 585. This study underscores the urgency for targeted actions to enhance ecosystem resilience and safeguard vulnerable communities from CDVWHS impacts. Identifying CDVWHS hotspots and comprehending their complex relationships with environmental factors are essential for developing effective adaptation strategies in a changing climate.Full Tex
Application of a Conceptual Hydrological Model for Streamflow Prediction Using Multi-Source Precipitation Products in a Semi-Arid River Basin
No full textManagement of the freshwater resources in a sustained manner requires the information and understanding of the surface water hydrology and streamflow is of key importance in this nexus. This study evaluates the performance of eight different precipitation products (APHRODITE, CHRS CCS, CHRS CDR, CHIRPS, CPC Global, GPCC, GPCP, and PERSIANN) for streamflow prediction in two sub-catchments (Chirah and Dhoke Pathan) of the data-scarce Soan River Basin (SRB) in Pakistan. A modified version of the hydrological model HBV (Hydrologiska Byråns Vattenbalansavdelning) known as HBV-light was used to generate streamflow. The model was separately calibrated and validated with observed and estimated precipitation data for streamflow simulation with optimized parameterization. The values of R2, NSE, KGE and PBIAS obtained during the calibration (validation) period for the Chirah sub-catchment were 0.64, 0.64, 0.68 and −5.6% (0.82, 0.81, 0.88 and 7.4%). On the other hand, values of R2, NSE, KGE, and PBIAS obtained during the calibration (validation) period for the Dhoke Pathan sub-catchment were 0.85, 0.85, 0.87, and −3.4% (0.82, 0.7, 0.73 and 6.9%). Different ranges of values were assigned to multiple efficiency evaluation metrics and the performance of precipitation products was assessed. Generally, we found that the performance of the precipitation products was improved (higher metrics values) with increasing temporal and spatial scale. However, our results showed that APHRODITE was the only precipitation product that outperformed other products in simulating observed streamflow at both temporal scales for both Chirah and Dhoke Pathan sub-catchments. These results suggest that with the long-term availability of continuous precipitation records with fine temporal and spatial resolutions, APHRODITE has the high potential to be used for streamflow prediction in this semi-arid river basin. Other products that performed better were GPCC, GPCP, and CHRS CCS; however, their scope was limited either to one catchment or a specific time scale. These results will also help better understand surface water hydrology and in turn, would be useful for better management of the water resources
On the Benefits of Bias Correction Techniques for Streamflow Simulation in Complex Terrain Catchments: A Case-Study for the Chitral River Basin in Pakistan
No full textThis work evaluates the suitability of linear scaling (LS) and empirical quantile mapping (EQM) bias correction methods to generate present and future hydrometeorological variables (precipitation, temperature, and streamflow) over the Chitral River Basin, in the Hindukush region of Pakistan. In particular, LS and EQM are applied to correct the high-resolution statistically downscaled dataset, NEX-GDDP, which comprises 21 state-of-the-art general circulation models (GCMs) from the coupled model intercomparison project phase 5 (CMIP5). Raw and bias-corrected NEX-GDDP simulations are used to force the (previously calibrated and validated) HBV-light hydrological model to generate long-term (up to 2100) streamflow projections over the catchment. Our results indicate that using the raw NEX-GDDP leads to substantial errors (as compared to observations) in the mean and extreme streamflow regimes. Nevertheless, the application of LS and EQM solves these problems, yielding much more realistic and plausible streamflow projections for the XXI century
Impacts of Climate Change on the Hydrometeorological Characteristics of the Soan River Basin, Pakistan
No full textThe global hydrological cycle is vulnerable to changing climatic conditions, especially in developing regions, which lack abundant resources and management of freshwater resources. This study evaluates the impacts of climate change on the hydrological regime of the Chirah and Dhoke Pathan sub catchments of the Soan River Basin (SRB), in Pakistan, by using the climate models included in the NEX-GDDP dataset and the hydrological model HBV-light. After proper calibration and validation, the latter is forced with NEX-GDDP inputs to simulate a historic and a future (under the RCP 4.5 and RCP 8.5 emission scenarios) streamflow. Multiple evaluation criteria were employed to find the best performing NEX-GDDP models. A different ensemble was produced for each sub catchment by including the five best performing NEX-GDDP GCMs (ACCESS1-0, CCSM4, CESM1-BGC, MIROC5, and MRI-CGCM3 for Chirah and BNU-ESM, CCSM4, GFDL-CM3. IPSL-CM5A-LR and NorESM1-M for Dhoke Pathan). Our results show that the streamflow is projected to decrease significantly for the two sub catchments, highlighting the vulnerability of the SRB to climate change
Land use and land cover dynamics: Implications for thermal stress and energy demands
No full textThis study examined the interaction between land use and land cover (LULC) dynamics, trend and thermal stress distribution using the universal thermal comfort index (UTCI) and different LULC classifications under two Coupled Model Intercomparison Project Phase 6 (CMIP6) Shared Socioeconomic Pathways (i.e., SSP 370 and 585) climate and land use scenarios for the historical (1959–2014) and future period (2045–2100). The moderate to strong cold stress in the annual and winter climatology in the midlatitudes was replaced by no thermal stress in the summer, while the summertime ranged from moderate to strong heat stress. A negative correlation was observed between thermal stress and southern hemispheric primary forests. Perennial croplands had the most dynamic changes in intensity during the historical period. Primary and secondary forests had an active influence on global thermal stress. Areas in the tropics recording moderate heat stress coincided with secondary nonforest, pastureland, and annual cropland expansions. The conversion of forest to range land and croplands and the subsequent negative forest trends increased the severity of thermal stress. The future projection showed intense thermal stress; however, the SSP-585 signals were more potent. As a result, cooling demands will rise, and heating demands will decline, yet, improved thermal comfort necessitates a higher cooling capacity, especially in the summer. Thermal stress may make it difficult for many cooling systems to meet people's energy demands. These could be a driving factor in shaping better land use policies, improving energy demand preparedness, and elucidating the potentially severe impacts of thermal stress.Full Tex
Terrestrial water storage in Australia under stress from compound climate extremes
No full textA large proportion of human population could be exposed to future risks from compound climate extremes, which are threatening food and water security. To understand the far-reaching impacts of these extremes on the livelihoods of current and future generations, we need models that are less ambiguous, better suited for impact studies, and more capable of advancing our understanding of future climatic conditions (e.g., rainfall and temperature). To advance such modelling capabilities for impact assessment of compound extremes in Australia, we develop a new framework to combine satellite gravity data with in-situ data and outputs from hydrological models to adjust for biases in the latest Coupled Model Intercomparison Project Phase general circulation models’ projections of water budget parameters. The impacts of compound climate extremes under different climate scenarios on the freshwater derived from these parameters were then assessed. Our findings show that the Australian east coast will experience a rise in compound hot and wet extremes, and changes to these compound extremes under different climate scenarios will drive freshwater deficits in Australia. The consequences of limiting global warming to different levels (historical, SSP 245, 370, and 585) on freshwater were also identified. We found significant freshwater declines over Australia with Western Australia being the most affected by compound climate extremes (wet and hot extremes) across all global warming scenarios. Considerable percentage changes exceeding -125% in freshwater have been linked to these compound extremes. Our results also reveal that evapotranspiration will emerge as a more crucial indicator to freshwater availability, and that atmospheric dynamics and moisture transport are expected to contribute to considerable changes in freshwater availability.Full Tex
The trend and spatial spread of multisectoral climate extremes in CMIP6 models
No full textClimate change could exacerbate extreme climate events. This study investigated the global and continental representations of fourteen multisectoral climate indices during the historical (1979–2014), near future (2025–2060) and far future (2065–2100) periods under two emission scenarios, in eleven Coupled Model Intercomparison Project (CMIP) General Circulation Models (GCM). We ranked the GCMs based on five metrics centred on their temporal and spatial performances. Most models followed the reference pattern during the historical period. MPI-ESM ranked best in replicating the daily precipitation intensity (DPI) in Africa, while CANESM5 GCM ranked first in heatwave index (HI), maximum consecutive dry days (MCCD). Across the different continents, MPI-LR GCM performed best in replicating the DPI, except in Africa. The model ranks could provide valuable information when selecting appropriate GCM ensembles when focusing on climate extremes. A global evaluation of the multi-index causal effects for the various indices shows that the dry spell total length (DSTL) was the most crucial index modulating the MCCD for all continents. Also, most indices exhibited a positive climate change signal from the historical to the future. Therefore, it is crucial to design appropriate strategies to strengthen resilience to extreme climatic events while mitigating greenhouse gas emissions
Understanding global groundwater-climate interactions
No full textGlobal warming is emerging as an important predictor of water availability and future water supplies across the world through inducing the frequency and severity in hydrological extremes. These extremes (e.g., drought) have potential impacts on groundwater, environmental flows, as well as increase social inequalities (limited access to water by the poor), among a range of other issues. Understanding the influence of global climate on groundwater systems is thus critical to help reshape global water markets through policies underpinned by the knowledge of climatic processes driving the water cycle and freshwater supply. The main aim of this study is to improve understanding of the influence of climate variability on global groundwater using statistical methods (e.g., multi-linear regression and wavelet analyses). The response of groundwater recharge to climate variability are assessed and the feasibility of identifying climatic hotspots of groundwater-climate interactions are explored (
). Generally, climate variability plays a major role in the distribution of groundwater recharge, evidenced in the groundwater-rainfall relationship (
ranging from 0.6 to 0.8 with lags of 1–5 months) in several regions (Amazon and Congo basins, West Africa, and south Asia). Some of the areas where no relationship exists coincide with major regional aquifer systems (e.g., Nubian sand stone in north Africa) in arid domains with fossil groundwater. Our results also show that groundwater fluxes across the world are driven by global climate teleconnections. Notable among these climate teleconnections are PDO, ENSO, CAR, and Nino 4 with PDO showing the strongest relationship (
= 0.80) with groundwater in some hotspots (e.g. in South America). The explicit role of the Pacific ocean in regulating groundwater fluxes provides an opportunity to improve the prediction of global climate impact on freshwater systems. As opposed to remarkably large productive hydrological systems (Amazon and Congo basins), in typically arid domains, groundwater could be restricted during prolonged drought, constraining the persistence of surface water in the maintenance of a healthy surface-groundwater interactions.Full Tex
Minimizing uncertainties in climate projections and water budget reveals the vulnerability of freshwater to climate change
No full textRising global temperatures will increase water in the atmosphere and diminish terrestrial water resources. Understanding changes in stored terrestrial water in surface or underground reservoirs is crucial for ecosystem and human sustainability. For example, modern agriculture often depends on groundwater and reservoirs, and water storage changes affect crop yield. Climate change will alter how much water is stored terrestrially; therefore, predicting these changes is crucial for adapting crops and other human water needs to changing water resources. Our findings reveal that warmer temperatures and shifting precipitation patterns can increase plant water consumption and evapotranspiration and reduce stored water. Stored water also depends on land use. For example, converting natural wetlands into urban areas reduces groundwater. The implications of warmer climates on water storage are region dependent, potentially exacerbating competition for water between human and natural ecosystems.Full Tex
