Future changes in annual, seasonal and monthly runoff signatures in contrasting Alpine catchments in Austria

Hanus, Sarah; Hrachowitz, Markus; Zekollari, Harry; Schoups, Gerrit; Vizcaíno, Miren; Kaitna, Roland

doi:10.5194/hess-25-3429-2021

Cited by 35 publications

(28 citation statements)

References 89 publications

(134 reference statements)

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“…Therefore, the results are also subject to potential deficiencies of the mHM model, as hydrological models are known to be a source of uncertainty in climate change impact studies (Vetter et al, 2017;Hattermann et al, 2018;Mendoza et al, 2015;Giuntoli et al, 2015;Hagemann et al, 2013). For instance, mHM does not explicitly consider the effect of vegetation dynamics associated with climate change that would modify runoff processes, which can be a limitation that is also observed in previous studies (Duethmann et al, 2020;Hanus et al, 2021;Wu et al, 2016). However, the mHM model used in this study has been thoroughly calibrated to provide realistic simulations of hydrological state variables and fluxes in the VRB (Dembélé et al, 2020a).…”

Section: Discussionmentioning

confidence: 99%

Contrasting dynamics of hydrological processes in the Volta River basin under global warming

Dembélé

Vrac

Ceperley

et al. 2021

Preprint

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Abstract. A comprehensive evaluation of the impacts of climate change on water resources of the West Africa Volta River basin is conducted in this study, as the region is expected to be hardest hit by global warming. A large ensemble of twelve general circulation models (GCM) from CMIP5 that are dynamically downscaled by five regional climate models (RCM) from CORDEX-Africa is used. In total, 43 RCM-GCM combinations are considered under three representative concentration pathways (RCP2.6, RCP4.5 and RCP8.5). The reliability of each of the climate datasets is first evaluated with satellite and reanalysis reference datasets. Subsequently, the Rank Resampling for Distributions and Dependences (R2D2) multivariate bias correction method is applied to the climate datasets. The corrected simulations are then used as input to the fully distributed mesoscale Hydrologic Model (mHM) for hydrological projections over the twenty-first century (1991–2100). Results reveal contrasting changes in the seasonality of rainfall depending on the selected greenhouse gas emission scenarios and the future projection periods. Although air temperature and potential evaporation increase under all RCPs, an increase in the magnitude of all hydrological variables (actual evaporation, total runoff, groundwater recharge, soil moisture and terrestrial water storage) is only projected under RCP8.5. High and low flow analysis suggests an increased flood risk under RCP8.5, particularly in the Black Volta, while hydrological droughts would be recurrent under RCP2.6 and RCP4.5, particularly in the White Volta. Disparities are observed in the spatial patterns of hydroclimatic variables across climatic zones, with higher warming in the Sahelian zone. Therefore, climate change would have severe implications for future water availability with concerns for rain-fed agriculture, thereby weakening the water-energy-food security nexus and amplifying the vulnerability of the local population. The variability between climate models highlights uncertainties in the projections and indicates a need to better represent complex climate features in regional models. These findings could serve as a guideline for both the scientific community to improve climate change projections and for decision makers to elaborate adaptation and mitigation strategies to cope with the consequences of climate change and strengthen regional socio-economic development.

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Section: Discussionmentioning

confidence: 99%

Contrasting dynamics of hydrological processes in the Volta River basin under global warming

Dembélé

Vrac

Ceperley

et al. 2021

Preprint

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“…In scenario 2 K A , we assume an unchanged land use and that vegetation has not adapted its root zone storage capacity to the aridity and seasonality of the 2 K climate. This scenario implies the stationarity of model parameters by using S R,max,A in both the historical and 2 K runs, a common assumption of many climate change impact assessment studies (Booij, 2005;de Wit et al, 2007;Prudhomme et al, 2014;Hakala et al, 2019;Brunner et al, 2019;Gao et al, 2020;Rottler et al, 2020;Hanus et al, 2021). This is the benchmark scenario against which we compare the hydrological response, considering non-stationarity of the system, as in the following three scenarios.…”

Section: Hydrological Change Evaluationmentioning

confidence: 99%

Ecosystem adaptation to climate change: the sensitivity of hydrological predictions to time-dynamic model parameters

Bouaziz

Aalbers

Weerts

et al. 2022

Hydrol. Earth Syst. Sci.

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Abstract. Future hydrological behavior in a changing world is typically predicted based on models that are calibrated on past observations, disregarding that hydrological systems and, therefore, model parameters may change as well. In reality, hydrological systems experience almost continuous change over a wide spectrum of temporal and spatial scales. In particular, there is growing evidence that vegetation adapts to changing climatic conditions by adjusting its root zone storage capacity, which is the key parameter of any terrestrial hydrological system. In addition, other species may become dominant, both under natural and anthropogenic influence. In this study, we test the sensitivity of hydrological model predictions to changes in vegetation parameters that reflect ecosystem adaptation to climate and potential land use changes. We propose a top-down approach, which directly uses projected climate data to estimate how vegetation adapts its root zone storage capacity at the catchment scale in response to changes in the magnitude and seasonality of hydro-climatic variables. Additionally, long-term water balance characteristics of different dominant ecosystems are used to predict the hydrological behavior of potential future land use change in a space-for-time exchange. We hypothesize that changes in the predicted hydrological response as a result of 2 K global warming are more pronounced when explicitly considering changes in the subsurface system properties induced by vegetation adaptation to changing environmental conditions. We test our hypothesis in the Meuse basin in four scenarios designed to predict the hydrological response to 2 K global warming in comparison to current-day conditions, using a process-based hydrological model with (a) a stationary system, i.e., no assumed changes in the root zone storage capacity of vegetation and historical land use, (b) an adapted root zone storage capacity in response to a changing climate but with historical land use and (c, d) an adapted root zone storage capacity considering two hypothetical changes in land use. We found that the larger root zone storage capacities (+34 %) in response to a more pronounced climatic seasonality with warmer summers under 2 K global warming result in strong seasonal changes in the hydrological response. More specifically, streamflow and groundwater storage are up to −15 % and −10 % lower in autumn, respectively, due to an up to +14 % higher summer evaporation in the non-stationary scenarios compared to the stationary benchmark scenario. By integrating a time-dynamic representation of changing vegetation properties in hydrological models, we make a potential step towards more reliable hydrological predictions under change.

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“…As a result of the rising temperatures, widespread and accelerating glacier retreat has been observed for several decades (e.g., Abermann et al, 2009;Sommer et al, 2020). Hydrological consequences include changes in water quantities (such as a transient increase in runoff) (Vormoor et al, 2015;Wijngaard et al, 2016), streamflow variability (van Tiel et al, 2019 and hydrograph timing, e.g., due to earlier snowmelt onset and a prolonged glacier melt period (Hanus et al, 2021;Kormann et al, 2016;Rottler et al, 2021Rottler et al, , 2020.…”

Section: Introductionmentioning

confidence: 99%

Suspended sediment and discharge dynamics in a glaciated alpine environment: identifying crucial areas and time periods on several spatial and temporal scales in the Ötztal, Austria

et al. 2022

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Abstract. Glaciated high-alpine areas are fundamentally altered by climate change, with well-known implications for hydrology, e.g., due to glacier retreat, longer snow-free periods, and more frequent and intense summer rainstorms. While knowledge on how these hydrological changes will propagate to suspended sediment dynamics is still scarce, it is needed to inform mitigation and adaptation strategies. To understand the processes and source areas most relevant to sediment dynamics, we analyzed discharge and sediment dynamics in high temporal resolution as well as their patterns on several spatial scales, which to date few studies have done. We used a nested catchment setup in the Upper Ötztal in Tyrol, Austria, where high-resolution (15 min) time series of discharge and suspended sediment concentrations are available for up to 15 years (2006–2020). The catchments of the gauges in Vent, Sölden and Tumpen range from 100 to almost 800 km2 with 10 % to 30 % glacier cover and span an elevation range of 930 to 3772 m a.s.l. We analyzed discharge and suspended sediment yields (SSY), their distribution in space, their seasonality and spatial differences therein, and the relative importance of short-term events. We complemented our analysis by linking the observations to satellite-based snow cover maps, glacier inventories, mass balances and precipitation data. Our results indicate that the areas above 2500 m a.s.l., characterized by glacier tongues and the most recently deglaciated areas, are crucial for sediment generation in all sub-catchments. This notion is supported by the synchronous spring onset of sediment export at the three gauges, which coincides with snowmelt above 2500 m but lags behind spring discharge onsets. This points at a limitation of suspended sediment supply as long as the areas above 2500 m are snow-covered. The positive correlation of annual SSY with glacier cover (among catchments) and glacier mass balances (within a catchment) further supports the importance of the glacier-dominated areas. The analysis of short-term events showed that summer precipitation events were associated with peak sediment concentrations and yields but on average accounted for only 21 % of the annual SSY in the headwaters. These results indicate that under current conditions, thermally induced sediment export (through snow and glacier melt) is dominant in the study area. Our results extend the scientific knowledge on current hydro-sedimentological conditions in glaciated high-alpine areas and provide a baseline for studies on projected future changes in hydro-sedimentological system dynamics.

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Future changes in annual, seasonal and monthly runoff signatures in contrasting Alpine catchments in Austria

Cited by 35 publications

References 89 publications

Contrasting dynamics of hydrological processes in the Volta River basin under global warming

Contrasting dynamics of hydrological processes in the Volta River basin under global warming

Ecosystem adaptation to climate change: the sensitivity of hydrological predictions to time-dynamic model parameters

Suspended sediment and discharge dynamics in a glaciated alpine environment: identifying crucial areas and time periods on several spatial and temporal scales in the Ötztal, Austria

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