ID72: The status and future of mountain waters

Abstract ID 460 | Date: 2022-09-14 10:09 – 10:18 | Type: Oral Presentation | Place: SOWI – Lecture hall HS1 |

Hafizi, Hamed (1,2); Sorman, Ali Arda (1)

Satellite-based precipitation products (SPPs) with high spatio-temporal resolution have become critical data sources for streamflow simulation in recent years. Their short latency (time lag), global and temporal coverage perfectly match many hydroclimatic studies requirements. However, the detailed evaluation of near real-time SPPs is essential before they become operational. Therefore, this study aims to evaluate the spatio-temporal consistency and hydrological utility of four SPPs (IMERGHHEv06, TMPA-3B42RTv7, PERSIANN-CCS, and PERSIANN) over a mountainous test basin (Karasu) in the eastern Turkey. The accuracy of selected SPPs compared to observed precipitation is expressed in the form of Kling-Gupta Efficiency (KGE) and Hanssen-Kuiper (HK) skill score is exploited to address the detectability strength of selected SPPs for five different precipitation intensities. Moreover, the hydrological utility of SPPs is evaluated using a conceptual hydrologic model under Nash-Sutcliffe Efficiency (NSE) and KGE indicators. Overall, IMERHHEv06 shows the highest performance (median KGE of 0.11) for the direct comparison with observed precipitation followed by PERSIANN (median KGE of 0.06), where TMPA-3B42RTv7 and PERSIANN-CCS show low performance (median KGE less than zero) comparatively. Furthermore, all SPPs show higher ability for streamflow simulation (KGE; 0.28–0.79) when the model is calibrated by each SPPs individually.

Abstract ID 511 | Date: 2022-09-14 10:18 – 10:27 | Type: Oral Presentation | Place: SOWI – Lecture hall HS1 |

Patil, Amol (1,2); Arnault, Joël (1); Fersch, Benjamin (1); Hendricks Franssen, Harrie-Jan (3); Kunstmann, Harald (1,2)

The non-invasive Cosmic-Ray Neutron Sensing (CRNS) method can be used to determine average soil moisture over a few tens of hectares. Combining the CRNS method with land surface models utilizing data assimilation techniques further provides the ability to predict soil moisture over kilometers. In this work, the Ensemble Adjustment Kalman Filter (EAKF) was used to assimilate the CRNS neutron counts in order to update the spatial soil moisture, soil infiltration, and evapotranspiration parameters of the Noah-MP land surface model. The study was conducted in the Rott and Ammer catchments in southern Germany, which contain the TERENO Pre-Alpine observatory and a dense network of cosmic ray neutron sensors. To assess the significance of parameter estimation, assimilation was performed for both soil moisture only and soil moisture plus parameter estimation scenarios. For both assimilation scenarios, the results show a strong improvements in field scale soil moisture characterization. The RMSE of simulated soil moisture was reduced by up to 66 % at field scale and up to 23 % at catchment scale. Furthermore, with 0.025 cm³/cm³ reduction in spatial bias, the spatial patterns in the field scale soil moisture showed improvements. These findings support the use of the CRNS technique to improve the spatial and temporal patterns of soil moisture at catchment scale by means of data assimilation.

Abstract ID 653 | Date: 2022-09-14 10:27 – 10:36 | Type: Oral Presentation | Place: SOWI – Lecture hall HS1 |

Mark, Bryan Greenwood (1); Fernández, Alfonso (2); Baraer, Michel (3)

Mountains are key hydroclimatic features that couple large-scale atmospheric processes with the earth surface, influencing the development of diverse waterscapes. In this presentation we summarize recent published knowledge on the hydroclimate of the American Cordilleras inspired in a recent collection of papers we were invited to edit. Decades of transformative research have highlighted how mountains are valuable for society, revealing that changes in these landscapes exert significant impacts on downstream hydrological regimes that support lives and livelihoods of millions. Yet despite sharing common features of verticality and orographic uplift, the complexity of mountain environments is an inherent feature that inevitably leads to geographic particularities, and challenges maintaining consistent observations. Nowadays, many of these mountain waterscapes are undergoing significant alterations in the context of ongoing climate and environmental changes. The vast latitudinal expanse of the Cordilleras that span from Patagonia to Alaska provides abundant examples of mountain hydroclimatic dynamics as they traverse entire atmospheric systems and delimit diverse climatic regions. Along this interhemispheric transect are similarities and contrasts in both biophysical and human components, whereby intercomparisons may broaden understanding. By learning how similar and how distinct is the research emerging in this context perhaps we, as a community of researchers, leverage our geographic diversity to gain new insights that so far have not been described in a frame facilitating cross comparisons along the American Cordilleras. Our aim with this presentation is to move us forward to questioning our perspectives and advance on coordinated efforts. We show that while the published studies highlight different aspects of the hydroclimate along the American mountains, the larger pool of submitted papers also show different operative understanding of the elements that define mountains and how they become important. Thus, while our intention is to show diverse research – distinct in methodology, scale, and topic – that is linked to a common mountain hydroclimatic theme, we also discuss how and why certain areas are weakly represented (i.e. Central America mountains) and provide ideas for a more comprehensive view of all these regions. The context of rapid climate and environmental change raises the value and urgency of interconnected mountain research that allows for comparative views along the American Cordilleras. We anticipate that such efforts might elucidate constructive perspectives on the changes taking place at unprecedented rates, and ideally may support future strategies to tackle these emergent challenges.

Abstract ID 351 | Date: 2022-09-14 10:36 – 10:45 | Type: Oral Presentation | Place: SOWI – Lecture hall HS1 |

Terzago, Silvia (1); Bongiovanni, Giulio (2,1); Von Hardenberg, Jost (3,1)

Mountain glacier shrinking, seasonal snow cover reduction and changes in the amount and seasonality of meltwater runoff are already affecting water availability for both local and downstream uses. Water is needed by different competing sectors including drinking water supply, energy production, agriculture, forestry, tourism, and extremely dry seasons can lead to economic losses. Reducing potential impacts of changes in water availability involves multiple time scales, from the decadal time scale, for the realization of water management infrastructures, to the seasonal scale, to plan the use of water resources and to allocate them with some lead time.

In the framework of the MEDSCOPE ERA4CS project we focused on the seasonal time scale and we developed a climate service prototype to estimate the temporal evolution of the depth and the water content of the snowpack with up to 7 months lead time. Forecasts are initialized on November 1st and run up to May 31st of the following year. The prototype has been co-designed with and tailored to the needs of water and hydropower plant managers and of mountain ski resorts managers.

We present the modeling chain, based on the seasonal forecasts produced by the ECMWF and Météo-France seasonal prediction systems, made available through the Copernicus Climate Change Service (C3S). Seasonal forecasts of precipitation, near-surface air temperature, radiative fluxes, wind and humidity are bias-corrected and downscaled to three high elevation sites in the North-Western Italian Alps, and used as inputs for a physically-based multi-layer snow model (SNOWPACK). The RainFARM stochastic downscaling procedure, adapted for mountain regions, is used for downscaling precipitation data, and stochastic realizations are employed to estimate the uncertainty due to the downscaling method.

The skill of the prototype in predicting the monthly snow depth evolution from November to May in each season of the hindcast period 1995-2015 is demonstrated using station measurements as a reference. We finally discuss implications of the forecast quality at different lead times as well as the added value of bias-correction and downscaling of precipitation data on snow depth forecasts. Real-time snow forecasts for the current season (2021-2022) and for earlier seasons are available on a dedicated web page at the link: http://wilma.to.isac.cnr.it/diss/snowpack/snowseas-eng.html

Abstract ID 421 | Date: 2022-09-14 10:45 – 10:54 | Type: Oral Presentation | Place: SOWI – Lecture hall HS1 |

Meyer, Joachim (1); Skiles, Mckenzie (1); Kormos, Patrick (2); Hedrick, Andrew (3)

The Western United States highly depends on freshwater supply from seasonal snowmelt. Mountain headwaters have a demonstrated decline in the extent and amount of snow, putting this previously consistent natural reservoir at risk. In most snow environments, the timing and magnitude of snowmelt are determined by absorbed (net) solar radiation, the difference between the incoming and reflected solar radiation, which is primarily controlled by the snow albedo. However, solar radiation and snow albedo are not commonly measured at instrumentation sites in the mountains, yet they maintain a high degree of spatial variability. With the sparsity of observations, process-based snow models commonly use a simplified time-decay function that can lead to errors in snowmelt rate and snow depletion timing. The errors are particularly seen in areas where light-absorbing particles darken snow, a common phenomenon in the Western US. One option to replace the simulated snow albedo is to use remote sensing products that previously had limited suitable spatial and temporal resolution products in the mountains. This gap was addressed by combining the MODIS Snow Covered Area and Grain Size (SCAG) products and Dust Radiative Forcing in Snow (DRFS) to produce an observed snow albedo. This study showcases the use of daily updated remotely sensed snow albedo from MODIS in a spatially distributed snow energy balance model in the East River Watershed, CO. Previous work established the model’s ability to capture overall mass balance in terms of accumulation timing and amount, but snow often melts too slowly and disappears too late. The results with MODIS observed albedo are compared against in-situ and airborne snow extent and depth observations to assess model improvements in snowmelt rate and snow depletion timing. The option to use remotely sensed snow albedo has the potential to enable a faster adaptation to ongoing and upcoming regional changes and enhance the runoff predictions of water forecasters.

Abstract ID 164 | Date: 2022-09-14 10:54 – 11:03 | Type: Oral Presentation | Place: SOWI – Lecture hall HS1 |

Thornton, James (1); Therrien, René (2); Mariéthoz, Gregoire (3); Linde, Niklas (4); Brunner, Philip (5)

Highly simplified approaches continue to underpin hydrological climate change impact assessments across the Earth’s mountainous regions. Fully-integrated surface-subsurface models may hold far greater potential to represent the distinctive regimes of steep, geologically-complex headwater catchments. However, their utility has not yet been tested across a wide range of mountainous settings. Here, an integrated model of two adjacent calcareous Alpine headwaters that accounts for 2D surface flow, 3D variably-saturated groundwater flow, and evapotranspiration is presented. An energy balance-based representation of snow dynamics contributed to the model’s high-resolution forcing data, and a sophisticated 3D geological model helped to define and parameterize the subsurface structure. In the first known attempt to calibrate a catchment-scale integrated model of a mountainous region automatically, numerous uncertain model parameters were estimated. The salient features of the hydrological regime could ultimately be satisfactorily reproduced – over an 11-month evaluation period, the Nash-Sutcliffe efficiency of simulated streamflow at the main gauging station was 0.76. Spatio-temporal visualization of the forcing data and simulated responses further confirmed the model’s broad coherence. Presumably due to unresolved local subsurface heterogeneity, closely replicating the somewhat contrasting groundwater level signals observed near to one another proved more elusive. Finally, we assessed the impacts of various common model simplifications and assumptions on key simulated outputs, finding strongly affected model performance in many cases, and explored the region’s future hydrology under not only future climatic but also future vegetation scenarios. Although certain outstanding challenges must be overcome if the global uptake of integrated models in mountain regions is to increase, our work demonstrates the feasibility and benefits of their application in such complex systems.

Abstract ID 290 | Date: 2022-09-14 11:03 – 11:12 | Type: Oral Presentation | Place: SOWI – Lecture hall HS1 |

Hanus, Sarah (1); Schuster, Lilian (2); Burek, Peter (3); Maussion, Fabien (2); Seibert, Jan (1); Marzeion, Ben (4); Wada, Yoshihide (3); Viviroli, Daniel (1)

In high mountain areas, glaciers can be considered an important part of the hydrological cycle and contribute significantly to runoff in the summer months. Due to climate change, the annual runoff volumes originating from glaciers are undergoing considerable change , making it essential to consider glacial melt in hydrological models when we want to model future hydrological changes realistically, especially with regard to mountain water resources. On a catchment scale, routines are available for incorporating glaciers. On a global scale, however, glaciers have been largely neglected so far. This is an important limitation of large-scale hydrological models often used for global climate change impact studies.

We present a framework to couple the global glacier model OGGM (Open Global Glacier Model) and the hydrological model CWatM (Community Water Model) on 5arcmin resolution globally. Both models are openly available. This framework facilitates an explicit inclusion of glacier runoff in large-scale hydrological modelling through dynamic modelling of glaciers and allows research into the hydrological importance of changing glaciers. Specifically, we evaluate how the inclusion of glaciers changes the amount and seasonality of simulated runoff in a large-scale hydrological model in the past and the future. Using selected major river basins in Europe and North America as study areas, benefits, challenges and limitations of the coupling are pointed out.

The large-scale glacio-hydrological modelling framework will be openly available to facilitate further research and the inclusion of glaciers in future large-scale hydrological studies. It can potentially also be used with other global hydrological models.

Abstract ID 372 | Date: 2022-09-14 11:12 – 11:21 | Type: Oral Presentation | Place: SOWI – Lecture hall HS1 |

Dixit, Ankur (1); Sahany, Sandeep (2); Mishra, Saroj Kanta (1)

We set up WRF with three nested domains using initial and lateral boundary conditions from ERA-Interim data. We performed six experiments using three microphysics (MP3, MP8, and WSM6) and two cumulus (KF, and BMJ) schemes. During DJF, MP8_KF, MP3_BMJ, and MP8_BMJ showed relatively lesser precipitation, however, WSM6_KF (~6.4 mm day-1) and WSM6_BMJ (~6.2 mm day-1) were found to have maximum precipitation. During JJAS, four (MP3_KF, MP3_BMJ, MP8_KF, WSM6_KF) out of six experiments failed to show the precipitation features in downstream foothills at the basin terminal, having average precipitation of ~3 mm day-1, which is much lower in comparison to APHRODITE (~7 mm day-1).

Afterwards, we performed the WRF-Hydro calibration using the WRF downscaled meteorological forcing (MP8KF, and WSM6_BMJ). The model was calibrated for the year 2003 and validated for 2004-2005. We found JJAS discharge was underestimated for MP8KF, possibly due to underestimation in the JJAS precipitation in MP8KF simulations. WSM6BMJ did reasonably well for the JJAS, but it showed some erroneous high peaks for the non-JJAS. Further, we utilized the best performing setup out of these simulations, each for MP8_KF and WSM6_BMJ meteorological forcing. We found that the weighted ensemble of these simulations produces satisfactory results (NSE=0.5), alongside the accuracy increased for the validation period (NSE=0.6).

The higher peaks and ridges of the basin are expected to experience lesser precipitation under both RCP4.5 and RCP8.5, having the largest decline towards the end-21^st-century under RCP8.5. It is noted that DJF precipitation to be decreased over the peaks, whereas JJAS is becoming wetter over the downstream region under RCP8.5. The near-surface air temperature is rising throughout the year under both RCP4.5 and RCP8.5. The study region is expected to become warmer during JJAS (DJF) by 1-3 (2.5-3.5) °C under RCP4.5 and 3-4 (4.5-5) °C under RCP8.5 for the end of the 21^st century

The surface runoff is expected to decrease almost throughout the basin with largest decline over high altitude regions under both RCP4.5 and RCP8.5 at the end-21^st-century. Whereas it is found to be increased over high peaks under RCP4.5 (RCP8.5) for early-21^st-century (mid-21^st-century). In addition, the snow water equivalent (SNEQV) was found to be decreased under RCP4.5, while increased for the higher elevated regions (> 5 Km). However, at the end-21^st-century, SNEQV is expected to decline throughout the year across the region under RCP8.5.

Abstract ID 738 | Date: 2022-09-14 11:21 – 11:30 | Type: Oral Presentation | Place: SOWI – Lecture hall HS1 |

Van Tiel, Marit (1); Fischer, Mauro (2)

During warm and dry weather events, meltwater from snow and glaciers can compensate for the lack of rainfall input and high evaporative demand in hydrological systems, thereby securing water availability. Previous studies have shown that the level of streamflow compensation mainly depends on the relative glacier cover in a catchment; the higher the glacier cover, the more streamflow is compensated. However, the streamflow responses to warm and dry (WD) events were also found to be highly variable, between the different summer months and between different years. Understanding this variability is important to assess when glaciers can compensate for a lack of rainfall-runoff and how this process is changing over time. Here, we examine this variability in observed streamflow responses of the last decades for a set of around 20 Swiss glacierized catchments with varying glacier cover. WD events were selected based on a precipitation, temperature and duration threshold (> 7 days) and the corresponding event streamflow was compared with the long-term mean. To explain the variability in event responses, we distinguish between catchment characteristics (spatial variability) and event characteristics (temporal variability). For the catchment characteristics, we determine besides relative glacier cover also other landcover types, such as rock, sediments and vegetation, to explore how catchment storage may influence the WD event responses. To explore the temporal variability, glacier cover changes, seasonal glacier mass balance anomalies, snowline elevations and antecedent meteorological conditions are considered. For each of these variables, hypotheses are formulated, which describe the effect on the streamflow response. These hypotheses are then tested by selecting specific WD events from the total sample of events. Overall, this study aims at providing detailed insights into the conditions in which glaciers compensate streamflow during WD periods, which will be important to assess the changing buffering role of mountain water towers under glacier retreat.

Abstract ID 159 | Date: 2022-09-14 11:30 – 11:39 | Type: Oral Presentation | Place: SOWI – Lecture hall HS1 |

Steiner, Jakob (1,2); Immerzeel, Walter (2)

Debris-covered glaciers have been investigated in detail from a glaciological perspective, however their role in catchment hydrology is less clear. Nearly 5% of all global mountain glacier ice is covered in debris, reaching up to 30% for some catchments in the Andes and the Himalaya. Debris thicker than a few centimeters generally inhibits melt, while thin debris can increase melt rates. As energy needs time to travel through the debris pack before reaching the ice surface the timing of melt is delayed. Additionally, melt water cannot drain as fast as over a clean ice and is retained and possibly refrozen in the debris layer, which is similar to unconsolidated soil. Based on multiple years of melt measurements on a debris-covered glacier in the Central Himalaya and concurrent monitoring of local climate and discharge, we show how debris cover influences the catchment’s hydrology. In the catchment, where 30% of the total glacier ice is covered in debris. During the monsoon 60% of the total ice melt originates from clean ice glaciers. This is reversed in spring, where the lower lying debris-covered ice provides nearly 80% of all glacier melt. Moreover, melt water from clean ice glaciers peaks around noon while melt from debris-covered ice peaks consistently 3 hours later. This potentially explains some of the very late and bimodal peak of discharge in the catchment. Discharge from glacier ice in the catchment exceeds 50% of the total discharge for 15% of the year. There are even periods when the glacier melt is larger than the observed river discharge. This suggests that a significant amount of melt water is routed through the debris layer and the subsurface before it leaves the catchment more than 24h after the melt occurred. As debris cover is expected to increase upwards, this delay in discharge is likely to become more pronounced in future.

Abstract ID 528 | Date: 2022-09-14 11:39 – 11:48 | Type: Oral Presentation | Place: SOWI – Lecture hall HS1 |

Postnikova, Taisiya (1); Rybak, Oleg (2,3,4); Huss, Matthias (5,6,7); Zekollary, Harry (5,6,8); Gubanov, Afanasy (1); Krylenko, Inna (1,2); Kornilova, Ekaterina (1,2); Shahgedanova, Maria (9); Nosenko, Gennady (10)

Debris cover is poorly represented in most glacier models although it plays a key role in the regulation of melt processes. Debris cover that is more than a few centimeters thick reduces melt by insulating glacier ice. Mass loss and retreat of debris-covered glaciers are slower than those of clear ice. Debris-covered glaciers are widespread in the North Caucasus. It is important to reliably quantify their evolution because the contribution of glacial runoff to total discharge is significant in the region.

This paper assesses the influence of debris cover on the evolution of glaciers in the basins of the Terek and Kuban rivers in the Northern Caucasus in the 21^st century and quantifies its effects on glacier mass balance, ice velocity, changes in glacier area, volume, and position of the glacier fronts as well as runoff. The GloGEMflow glacier model is used to which a new debris cover dynamic module has been introduced. The mass balance is calibrated separately for the explicitly modelled debris cover and for clean-ice glaciers (debris cover is implicit in the degree-day factor calibration). The model is calibrated using newly mapped debris cover outlines and ice thickness data from Rounce et al. (2021). The debris evolution is simulated with a steady deposit model adapted from Verhaegen et al. (2020) and Anderson & Anderson (2016), where debris input onto glacier surface is generated from a fixed point on the flow line. The outputs from the glacier model, as well as future climate projections, are used to force the hydrological model ECOlogical Model for Applied Geophysics (ЕСОМАG) in order to assess changes in runoff throughout the 21st century.

The debris cover evolution patterns differ significantly between the Terek and the Kuban basins. In the Kuban basin, glaciers positioned generally at lower elevations retreat rapidly and lose ice at the debris-covered glacier tongues. In the Terek basin, expansion of the supraglacial debris cover is observed. It causes a six times larger effect on glacier volume evolution than for the Kuban basin glaciers. We compare glacier evolution including evolution of debris cover and changes in runoff for the explicit and implicit debris cover formulation for five SSP scenarios from CMIP6.

The reported study was funded by the RFBR and the Royal Society grants 21-55-10003 and IECR2202193; the work of T. Postnikova was supported by the RFBR grant 20-35-90042.

Abstract ID 341 | Date: 2022-09-14 11:48 – 11:57 | Type: Oral Presentation | Place: SOWI – Lecture hall HS1 |

Gong, Yongmei; Rogozhina, Irina

Jostedøla river basin is amongst many highly glacierized drainage basins with complex terrain and local climate in Western Norway. Most headwater streams of the Jostedøla river and its tributaries are connected to the outlet glaciers of the largest icecap in mainland Europe – Jostedalsbreen icecap. These headwater streams contribute to hydropower production and support economically important fisheries.

In this study, we utilize a linear reservoir, water routine model with a daily temporal and 100m ×100m spatial resolution to investigate glaciers’ contribution to streamflow and the climate elasticity of ungauged headwater stream in Jostedøla river basin in 2000-2014. The results are analyzed for 19 sample sites located at the glacial headwater streams as well as the main river. The mean annual contribution of the water coming from the glacier-covered region ranges from 61.5% downstream the river to 100% at the glacier terminus. These waters are composed of mostly snow meltwater and glacier meltwater with rainwater being a minor contributor. The proportion of snow meltwater and glacier meltwater are different at different sample sites. The climate elasticity index of river basin incorporating both temperature and precipitation changes ranges from 0.7 to 1.7 with different precipitation change scenarios.

Abstract ID 429 | Date: 2022-09-14 13:30 – 13:39 | Type: Oral Presentation | Place: SOWI – Lecture hall HS1 |

Aubry-Wake, Caroline (1); Nicholson, Lindsey (2); Prinz, Rainer (2); Pomeroy, John W (1)

Mountain glaciers worldwide are retreating, with varied consequences for downstream water supply. With a warming climate and shifting precipitation phase, timing and volume, the hydrological processes occurring in headwater mountain catchments are changing. These changes were investigated in the well-studied Peyto Glacier Research Basin, Canadian Rockies, and the Rofental Basin, Austrian Alps, using a semi-distributed glacio-hydrological model in the Cold Region Hydrological Modelling platform (CRHM) which includes process representation for energy-balance snow and ice melt, ice melt under debris, blowing snow sublimation and redistribution, avalanches, and subsurface water storage and flow. The CRHM models were forced with bias-corrected, high-resolution, dynamically downscaled atmospheric modelling outputs, available at 4km resolution from the WRF model for Peyto, and at 2km resolution from the COSMO for the Rofental. Current climate conditions (the early 2000s) and pseudo-global-warming conditions, which represent simulated weather perturbed by an end-of-century RCP 8.5 scenario, were compared for both basins. The CRHM models were evaluated in each basin with available field data from glacier mass balance, snow accumulation and streamflow observations. Both basins are composed of similar mountain landforms and are predicted to be almost glacier-free by 2100. They have contrasting areas, current glacier cover, and elevation ranges. Under current conditions, the Peyto and Rofental basins both have basin-averaged annual air temperature near -3.8°C; this warms by 5°C in both PGW simulations. The precipitation regime in both basins is currently dominated by snowfall, but Peyto basin receives 15% more precipitation and has a larger proportion of precipitation falling as snow than Rofental. Under PGW, precipitation in Peyto Basin increases by 16%, largely as greater summer rainfall. In contrast, precipitation in Rofental Basin decreases due to a substantial decline in snowfall and increase in rainfall. These contrasting shifts in precipitation, combined with a differences basin area, elevation range and initial glacier cover, cause differing streamflow responses to climate change. Peyto Glacier Research Basin end-of-century streamflow decreases by 7%, with a strong decrease in late summer flow and a 30% decrease in peak flow, whose timing advances by one month. In contrast, Rofental Basin streamflow decreases by 33%, primarily in mid to late summer but sustains relatively unchanged spring streamflow. By comparing two well-studied headwater glacierized basins in differing mountain ranges, this study provides insights into the role of basin topography and precipitation change in causing a shift in streamflow response to climate change.

Abstract ID 318 | Date: 2022-09-14 13:39 – 13:48 | Type: Oral Presentation | Place: SOWI – Lecture hall HS1 |

Baraer, Michel (1); Mckenzie, Jeff (2); Mark, Bryan (3); Lauren, Somers (4)

Once a mountain glacier begins retreating, discharge at the watershed outlet increases until a peak known as peak water. Passed this point, glaciers start losing hydrological influence as their volume becomes insufficient to sustain the release of high meltwater volumes.

Beyond that macroscopic and coarse description, the ongoing cryospheric losses produce numerous, complex, and multifaced impacts on water resources. We here propose an overview of the main learnings arising from the research we conducted in a glacierized catchment in the tropical Andes and in the Canadian Subarctic over the past 15 years.

Through different examples, covering water quality and quantity, we illustrate how mountainous glacierized catchments are complex multicomponent systems in which numerous cryospheric, hydrological, and hydrogeological components interact with each other in spatially and timely variable ways. Those components differ from region to region and their level of contribution varies from watershed to watershed within a given region. The relative contribution of the non-glacial sources generally increases as glaciers lose mass and hydrological influence at the watershed scale.

We explore

We conclude that water availability for human, economic, and ecological uses within and downstream of glacierized watersheds remains site-specific.

Abstract ID 544 | Date: 2022-09-14 13:48 – 13:57 | Type: Oral Presentation | Place: SOWI – Lecture hall HS1 |

Drenkhan, Fabian (1,2,3); Buytaert, Wouter (1); Mackay, Jonathan D. (4,5); Barrand, Nicholas E. (5); Hannah, David M. (5); Huggel, Christian (3)

In many mountain regions, the cryosphere is a crucial component of water provision to downstream societies, as it contributes to dry-season flows and sustaining diverse ecosystems in many regions of the world. However, many of the world’s glacierized watersheds experience far-reaching changes due to declining glaciers and snowpack, climate change impacts on the non-cryosphere part of the catchment, and socioeconomic development. The implications for downstream water supply are therefore manifold and complex. Coupled effects of reduced and less reliable water availability, changes in water quality, and growing water demand exert increasing pressure on water resources and threaten future water security and management.

In this study we argue that the limited understanding of interactions between the cryosphere, glacial and non-glacial water stores, river runoff and people hamper climate change adaptation and long-term water security. Meaningful assessments of mountain water security require therefore a holistic social-ecological perspective that interlinks the wider catchment hydrology considering both, surface and subsurface stores, and people including human water demand with improved data and process understanding. Water security assessments can then be guided by a fully coupled hydrological risk framework. This approach needs to integrate multiple social-ecological vulnerabilities as well as the degree of exposure to water shortage under a variety of possible future scenarios of glacier shrinkage, catchment alteration and socioeconomic development. Essentially, this requires a good understanding of interrelated upstream-downstream systems and the spatiotemporal propagation of meltwater through the terrestrial water cycle.

Improved data and more diverse knowledge collection is a priority, and these should be integrated into a collaborative science-policy-community framework. This can support a wide set of incremental and transformational strategies that guide effective and robust adaptation pathways. These may include, among other, exploring catchment-specific benefits of nature-based solutions to increase the buffer function of wider catchment hydrology to water loss from glacier shrinkage and to enhance long-term water security in a watershed context.

Abstract ID 758 | Date: 2022-09-14 13:57 – 14:06 | Type: Oral Presentation | Place: SOWI – Lecture hall HS1 |

Pelto, Ben M; Moore, R D

The downstream effects of shrinking glaciers on water supply and water quality have received substantial attention using both empirical analysis of historic data and computer modelling to make future projections under climate-change scenarios. Most modelling studies replaced glacier cover with open or alpine land cover following retreat and have not accounted for vegetation or soil development on deglaciated areas or formation of proglacial lakes. The objective of this study is to quantify the historic and potential future hydrologic impacts of land cover change on a glacierized mountain catchment. The study focused on the catchment area for Bridge River in the southern Coast Mountains of British Columbia, which contains Bridge Glacier, a lake-terminating valley glacier.

Field observations and remotely sensed data are used to document glacier retreat, lake surface temperatures, and the evolution of vegetation in deglaciated forelands and valley walls. Since 1980, the Bridge Glacier terminus has retreated 4.75 km. Glacier area declined from 89 to 74 km², while the proglacial lake grew from 2 to 7.6 km² and vegetation cover increased from 33 to 46 km². While the terminus continued to calve icebergs in 2021, iceberg density in the lake peaked around 2011 and is currently minor. This reduction in iceberg density has been accompanied by increases in remotely sensed lake surface temperatures and river temperatures observed at the gauging station two kilometers downstream of the lake outlet.

The valley sidewalls have exhibited substantial expansion of shrubby vegetation, especially in areas where soil moisture is supported by topographic convergence. Scattered coniferous trees have established in the deglaciated valley wall downslope of subalpine forest above the Little Ice Age trimline. Using satellite-based vegetation indices, field surveys of vegetation, mapped surface exposure ages, and topographic data, we are developing an auto-logistic spatiotemporal model of vegetation expansion. This model will be combined with existing projections of future glacier change to represent future land cover change within the catchment.

The Raven modelling platform will be used to simulate streamflow for historic and projected future conditions. The model will incorporate dynamic land cover, and calibration will be based on a multi-criterial approach involving streamflow, snow cover and glacier mass changes. The calibrated model will be used to diagnose the relative roles of climate change, glacier retreat and vegetation succession on historic streamflow, and to project changes in streamflow under future climate and land-cover change scenarios.

Abstract ID 381 | Date: 2022-09-14 14:06 – 14:15 | Type: Oral Presentation | Place: SOWI – Lecture hall HS1 |

Kraaijenbrink, Philip; Sutanudjaja, Edwin; Van De Wal, Roderik; Bierkens, Marc; Immerzeel, Walter

The excess meltwater that results from climate change induced mass loss of mountain glaciers is an important contributor to sea level rise (SLR). Up to now, large scale glacier observations and models have been used to estimate the amount of generated excess meltwater and its transient contribution to SLR under the assumption that meltwater is added to the ocean instantaneously and in its entirety. However, hydrological processes and water consumption during the transit from glacier to the ocean may affect the amount and timing of glacier runoff that eventually drains into the ocean. We hypothesize that some of the lost glacier ice may not reach the ocean at all or only at a much later stage.

In this study, we assessed the impacts of the hydrological pathway of meltwater from the glacier snouts to the ocean in the Indus Basin. With its large glacier ice reserves, relatively arid climate and large irrigation scheme, this basin provides the optimal case study for such an assessment. We coupled output from a detailed glacier model to the fully distributed hydrological model PCR-GLOBWB 2, and forced the models with bias-corrected historical and future climate data from the third phase of the Inter-Sectoral Impact Model Intercomparison Project (ISIMIP3).

Our findings show that, particularly in (periods of) dry years, considerable fractions of excess glacier meltwater do not enter the ocean. The changes in hydrological stores indicate that much of it is withdrawn for surface water irrigation of cropland and eventually evaporates as a result. The increased surface water availability due to the presence of excess glacier meltwater leads to a lowering of groundwater irrigation and a reduction of the unsustainable depletion of the basin’s groundwater store. In the future, increased availability of excess glacier meltwater and increased water withdrawals due to continued climate change and socioeconomic developments exacerbate these effects. Up to the end of century, depending on the specific climate scenario, around 12% of excess glacier meltwater does not enter the ocean directly.

We conclude that not all glacier mass loss can be assumed to contribute (directly) to SLR, which may lead to overestimation of future sea level rise. Further research is necessary to estimate the breadth of these effects at a global scale, but we hypothesize that this may also play a role in other glacierized basins with semi-arid downstream regions and considerable distances between the glaciers and the ocean.

Abstract ID 516 | Date: 2022-09-14 14:15 – 14:24 | Type: Oral Presentation | Place: SOWI – Lecture hall HS1 |

Zemlianskova, Anastasiia (1,2); Makarieva, Olga (1,2); Nesterova, Nataliia (1); Alexeev, Vladimir (1); Shikhov, Andrey (3); Ostashov, Andrey (1)

Aufeis (naled, in Russian) is a specific form of seasonal glaciation that is typical for mountainous permafrost environment. The area of aufeis fields can be measured in tens of square kilometres, and the ice thickness may reach 10-12 m.
The distribution of the aufeis is closely related to the structure of the relief, with its dissection and morphological features of river valleys in the region.
The goal is to assess the distribution of groundwater aufeis (area from 0.01 to 81.1 sq.km) by elevation that forms in the river valleys of the North-East of Russia using historical and modern data.
The study used the data of the Cadastre of aufeis at the North-East of the USSR (1958), which was the first data generalization accounting for aufeis and their characteristics for the study area. Aufeis detection in current climate was conducted based on the Landsat-8 OLI satellite images, from 2013 to 2019, late spring images were selected to detect the maximum possible number of aufeis fields and their maximum area.
The results suggest an irregular distribution of aufeis by elevation which does not relate to the size of aufeis. For large rivers of the North-East of Russia, such as the Indigirka, Yana, Kolyma, Anadyr and Penzhina, the aufeis belt is found in the altitudes of 1100-1200, 800-900, 700-800, 300-500 and 400-600 m correspondingly.
The upper boundary of the seasonal glaciation is located within the heights of 1500-2000 m. The lower boundary lies at the level of 100 m, but in some basins, it can rise up to 700 m. Below these elevation, the slopes of river valleys’ profile significantly decrease and do not fulfil the conditions for the release of groundwater to the surface for the formation of aufeis.
In general, the aufeis distributions by elevation as assessed with the Cadastre (1958) and Landsat data are quite similar, although there are some differences that are elevation-specific. At lower elevations the number of aufeis according to Landsat data is higher than presented in the Cadastre (1958). At the upper elevations, more aufeis are identified in the Cadastre data than by recent satellite images.
Changes of aufeis morphometric characteristics with the elevation may reveal the dynamic of other processes and their transformation due to climate change impact, such as permafrost, groundwater, etc.
Support. RFBR projects 20-05-00666 and 19-55-80028, SPbU project id75295776.

Abstract ID 611 | Date: 2022-09-14 14:24 – 14:33 | Type: Oral Presentation | Place: SOWI – Lecture hall HS1 |

Mckenzie, Jeffrey (1); Somers, Lauren (2)

Groundwater and surface water are an integrated system and understanding both components is critical for managing mountain water resources. The hydrology of mountain regions is complex due to steep elevation gradients, large ranges in climate, complex geology and geomorphology, the presence or absence of cryosphere elements, and ongoing climate change. Within this dynamic setting, groundwater (i.e., water that is stored in and flows through the subsurface) is an important component of the hydrologic cycle in mountainous terrains. A proportion of rain, snowmelt, and or glacial melt infiltrates into the subsurface and recharges groundwater. Within mountain groundwater systems, there are many pathways that infiltrated water may travel. From shorter to longer residence times, and from larger to smaller contributing areas, these include:

• flow through highly permeable proglacial deposits (e.g., talus slopes) discharging to ephemeral streams within days,
• surface sediment and shallow bedrock aquifers, recharged during seasonal rain/snow events, contributing to stream baseflow over seasonal to interannual cycles, and
• deeper mountain system recharge (e.g., mountain front or mountain block recharge), that recharges adjacent valley aquifers over years to decades.

In our presentation, we argue that the partitioning of groundwater between these different subsystems is complex but critical to understand the role of mountains as the world’s water towers. Within this context, there are many critical outstanding questions: What is the amount of water entering each of these subsystems? How do we quantify the partitioning of water between these different subsystems? And how will climate change, reduced cryosphere, and/or human activities affect groundwater systems and subsystem partitioning?

Abstract ID 307 | Date: 2022-09-14 14:33 – 14:42 | Type: Oral Presentation | Place: SOWI – Lecture hall HS1 |

Somers, Lauren Dorothy (1); Samways, Jenacy (1); Mckenzie, Jeffrey (2)

Mountain water resources are of particular importance for downstream populations but are threatened by decreasing water storage in snowpack and glaciers. Baseflow (groundwater discharge) sustains mountain streamflow during times of low precipitation, snowmelt or ice melt. Recent advances suggest that high mountain groundwater may provide some resilience—at least temporarily—to mountain water resources under climate-driven glacier and snowpack recession. However, as mountain climates change, modelling suggests that increasing evapotranspiration could lead to declining groundwater recharge in some mountain ranges. Given the lack of observation wells in mountains, little field evidence is available to confirm if, where, and when this occurs, and the consequences for water resources.

In this presentation, we first outline key groundwater processes and aquifers in mountain regions based on our recent review paper. We will summarize the hypothesized direct and indirect impacts of climate change on mountain groundwater systems. These impacts include direct mechanisms (more/less precipitation and increased evaporation with rising air temperatures) as well as indirect impacts through the cryosphere (e.g., loss of glacier melt recharge, changing snow-rain fraction), ecosystem (increasing evapotranspiration) and human interventions (e.g., land use and adaptation).

Second, we will present preliminary results investigating long-term changes in groundwater levels in mountain regions of Canada and the United States. We compile and analyze a large dataset of public groundwater observation well records, filtered to include mountain wells with more than ten years of continuous monthly (minimum frequency) data. We apply the Seasonal Kendall test for monotonic trend to determine if there is field evidence for changing groundwater levels in these mountains. Next, we apply multivariate statistical methods to determine which factors (e.g., climate, topography, elevation, and geology) are linked to temporal trends in mountain groundwater storage and therefore vulnerability of mountain water resources under climate change.

Abstract ID 588 | Date: 2022-09-14 14:42 – 14:51 | Type: Oral Presentation | Place: SOWI – Lecture hall HS1 |

Domènech, Marta; Travesset, Oriol; Trapero, Laura; Albalat, Anna; Pons, Marc

The Pyrenees, as well as other mountainous areas, are the main source of fresh water for the lowland regions but also include high water-consuming areas. The context of global change leads to spatiotemporal changes in water availability posing a challenge in both mountains and adjacent lowlands.

This case study analyzes the future water resources in the Principality of Andorra, where the confluence of climate change and a socioeconomic model based on intensive water use could threaten the future sustainability of the system. The main analysis is carried out using the WEAP (Water Evaluation and Planning System) tool, implementing a model that explores the future evolution of water resources. We propose an integrated approach combining hydrological and water resources management modeling to better understand the future impacts of the combined physical and socioeconomic changes on the water resource. Water availability and demand are analyzed in extreme future scenarios (i.e., combining extreme climate drought periods and high socioeconomic growth) up to 2050 to anticipate future spatiotemporal water tensions between the main activity sectors in the country.

The results identify winter and spring as the most vulnerable seasons where the convergence of low water availability and high demand may lead to problems on the water supply of some key sectors of activity such as ski resorts or the hydropower sector. The simulated scenarios estimate a severe decrease of the rivers’ streamflow affecting ecosystem functions. Frequency and duration of drought periods will probably determine the long-term ecological impacts on the Pyrenean rivers and its ecological functions. In this context of global change, there is a need of more research focusing on this topic to anticipate tensions between competing users and design water management strategies to ensure water supply along with preserve rivers ecosystems.

Abstract ID 493 | Date: 2022-09-14 14:51 – 15:00 | Type: Oral Presentation | Place: SOWI – Lecture hall HS1 |

Lutz, Arthur (1); Immerzeel, Walter (1); Siderius, Christian (2); Wijngaard, René (3); Nepal, Santosh (4); Shrestha, Arun (4); Wester, Philippus (4); Biemans, Hester (5)

Irrigated agriculture on the Indo-Gangetic plain in South Asia depends on meltwater, monsoon rains, and groundwater availability. Climate change alters the hydrological cycle and causes shifts in the timing, composition and magnitude of these sources of water supply. In particular in the mountainous headwaters in the Hindu Kush, Karakoram, and Himalaya, hydrological shifts are projected. Simultaneously, socioeconomic growth causes a strong increase in water demand downstream. Here we use a high-resolution cryosphere-hydrology-crop model forced with an ensemble of climate and socioeconomic projections to assess how the sources of irrigation water supply in the Indus, Ganges, and Brahmaputra river basins may shift during the 21^st century, under changing supply and demand.

We find clear increases in the importance of meltwater as well as groundwater for irrigated agriculture. An earlier melt peak increases meltwater withdrawal at the onset of the cropping season in May and June in the Indus, whereas increasing peak irrigation water demand during July and August aggravates non-renewable groundwater pumping in the Indus as well as Ganges basins, despite overal increases in runoff. In addition, increasing inter-annual variability in rainfall-runoff increases the need for meltwater as well as groundwater to complement rainfall-runoff during future dry years. These findings provide important information to guide climate change adaptation for the regional agricultural sector.

Abstract ID 179 | Date: 2022-09-14 15:15 – 15:17 | Type: Poster Presentation | Place: SOWI – Garden |

Pradhan, Pragya (1); Shrestha, Sangam (1); Shanmugam, Mohana Sundaram (1); Virdis, Salvatore G.p. (2)

The climate change impact on flow regimes in the different physiographic regions (Low-lying plain areas, Middle Mountains, and High Himalayas) of the Koshi River Basin, Nepal was studied using the Soil and Water Assessment Tool (SWAT). This study analyses the climate projections of climate variables from the latest Coupled Model Intercomparison Project (CMIP6) from 2015 to 2100 with four climate models (BCC, CANESM-CCCma, CNRMCM-CERFACS, and IPSL) under two shared socio-economic pathways (SSP2-4.5 and SSP5-8.5). The SWAT model was first calibrated (1985-2006) and validated (2009-2012) at a daily timescale for simulation of streamflow in every physiographic region of the Koshi River Basin. The flow is also analyzed based upon the magnitude, intensity, and duration flow parameters. The results show that the GCM-specific changes in the climate variables also have an impact on the regional and seasonal scales. The projection showed a wider range of deviation with respect to the baseline, predominantly increasing heavy rainfall in the Middle Mountains and High Himalayas region of the basin. The summer rainfall and winter temperature of the basin expect to increase more than 20% which indicates the risk of extreme climate events in the future. The SWAT model predicted an annual increase in streamflow by 19% and 60% under SSP2-4.5 and SSP5-8.5, respectively. Also, climate change is expected to increase the maximum monthly streamflow, especially from June-September with the potential of extreme flow events in the Koshi River Basin. The predicted high and moderate rise in streamflow under SSP5-8.5 suggests the need for an adaptation plan and mitigation strategies in the basin.

Abstract ID 497 | Date: 2022-09-14 15:17 – 15:19 | Type: Poster Presentation | Place: SOWI – Garden |

Kayastha, Rakesh (1); Yang, Min (2); Kayastha, Rijan Bhakta (1); Shrestha, Reeju (1)

Glacier, snow and permafrost play an important role in the Himalayan river basins and change in climatic variability directly affects these cryospheric elements. The large portion of river discharge in Himalayan river basins comes from snow and glacier ice melt, and their contributions to river flow are critical to fully understanding current and future scenarios. The glacier’s status and its response to different time-series climatic variability need to understand for the past and future glacier dynamics. This study aims to estimate the cryospheric and hydrological regime of the Marsyangdi River Basin (MRB) of Nepalese Himalaya covering an area of 4026 sq. km. MRB comprises 20 % of the glacierized area, the future glacier change is evaluated using the Open Global Glacier Model (OGGM) with three Shared Socioeconomic Pathways (SSP) scenarios from Coupled Model Intercomparison Project- Phase 6 (CMIP6). The MRB glacier area from 2021 to 2100 is expected to decrease by 32%, 47%, and 66% under SSP1-2.6, SSP2-4.5, and SSP5-8.5 scenarios. Similarly, the glacier volume is also expected to decrease by 56%, 62%, and 73% till 2100 under those three scenarios. The glacier area and volume change from the glacier dynamics model is integrated with a distributed glacio-hydrological model, Glacio-hydrological Degree-day Model (GDM) to simulate the future hydrological regime of MRB. The GDM model is calibrated with the observed discharge to estimate the contributions of snowmelt, icemelt, rainfall, and baseflow in river flow. The GDM-estimated future changes in river flows reveal that glaciers icemelt from (debris-free, debris-covered) and snowmelt contributions are important for the water supply in MRB. The change in glacier area and volume under the SSP5-8.5 scenarios, remarkably affect the total river flows and tends to decrease slightly by the end of this century, whereas the glacier ice melt contribution increases after mid-century in the MRB. Similarly, the snowmelt contribution to river flow decreased after the mid-century. The future cryospheric and hydrological regime is effectively evaluated by integrating the glacier dynamics and a glacio-hydrological model. This integrated approach could potentially improve understanding of the hydrological system dynamics and potential impacts of climate change in the Himalayan glaciated river basins.

Abstract ID 763 | Date: 2022-09-14 15:19 – 15:21 | Type: Poster Presentation | Place: SOWI – Garden |

Marke, Thomas

Mountain regions are naturally characterized by steep climatic gradients and a high variability of meteorological conditions over short distances and periods of time. At present, many open-source models are applied by the hydrological community (e.g., the hydrologically enhanced version of the Weather Research and Forecasting Modeling System (WRF-Hydro, Gochis et al., 2016) or the Community Water Model (CWatM, Burek et al. 2020)) to simulate hydrological processes at different temporal and spatial scales, often driven by comparatively coarsely resolved climate data, e.g. from reanalysis initiatives like ERA5 provided by the European Centre for Medium-Range Weather Forecasts (ECMWF). These data sets provide valuable climatic information, particularly in regions with scarcely available station recordings as well as for model application at larger (e.g., continental) scales. However, when hydrological simulations at higher spatial resolution or in mountainous terrain are envisaged, topographic effects (e.g., on shortwave radiation fluxes) are not sufficiently resolved when simply interpolating from the coarser grid of the meteorological input (typically 1-10 km resolution) to the finer grid applied by the hydrological model (typically 100-1000 m resolution), inducing systematic biases in the subsequent hydrological simulations.
The here presented R-package CliMapR includes different approaches for a quasi-physically based remapping of various meteorological variables as required as input for most hydrological models (e.g., temperature, precipitation, air humdity, solar and longwave radiation as well as wind speed). The remapping software combines algorithms available from previous studies (e.g., Corripio 2003, Liston and Elder 2006, Marke 2008, Marke et al. 2013) in combination with ordinary direct interpolation techniques to topographically adjust coarsely resolved meteorlogical input from gridded data sets as well as from point-scale station observations. The present version of CliMapR includes interfaces to many common data products (e.g., ERA5/ERA5Land data) as well as data formats (e.g., ASCII or netCDF format) and is easily extendable to deal with different data sources and formats in the future. As plots for the whole model domain and selected output locations are exported by default, the remapping tool is particulary suited to be applied in a teaching context. This poster presentation provides an overview of the software’s functionality as well as an exemplary application in a hydrological context by using meteorlogical input remapped using CliMapR for the simulation of water fluxes in selected mountain catchments in Tyrol (Austria).

Abstract ID 896 | Date: 2022-09-14 15:21 – 15:23 | Type: Poster Presentation | Place: SOWI – Garden |

Llodrà-Llabrés, Joana (1); Martínez-López, Javier (2); Postma, Thedmer M. (2); Navarro, Carlos (2); Pérez-Martínez, Carmen (1); Alcaraz-Segura, Domingo (3)

High-mountain lakes provide crucial ecosystem services (ES) such as non-drinking water resources, biodiversity hosting and maintenance, recreational purposes and aesthetic value, among others. However, these ecosystems are still poorly understood mainly due to their typical difficult access and the large amount of resources needed for their sampling and study making it difficult to maintain a regular monitoring based on field campaigns. These ecosystems are amongst the most vulnerable systems to global change, especially in the Mediterranean region, and have shown to be sentinels of regional global change. Due to their socio-economic, scientific and environmental relevance and their sensitivity to climate change, they require strategies for their optimal management. Hence, the main aims of this study are: a) to assess how chlorophyll-a (chl-a) concentration in shallow (<10 m) small (<1 ha) high-altitude lakes can be monitored through high (Sentinel-2; 10-20 m) and very-high spatial resolution (Worldview-3; 0.3 m) satellite imagery; and b) create a remote monitoring methodology to overcome the accessibility issue of high-mountain ecosystems.

A systematic literature review of chl-a retrieval indexes was first conducted to identify a comprehensive set of relevant indexes for our study area, input parameters and atmospheric corrections. Our study is focused on remote high-mountain lakes of the Sierra Nevada National Park, a biodiversity hotspot located in SE Spain. In a set of several lakes (between 2800 and 3100 m a.s.l.), chl-a concentration was regularly measured in several field campaigns conducted during 2020, 2021 and 2022. Field measurements were used as a response variable to train several linear and machine learning models. Different models were trained for each lake individually and for the whole set. Several co-variables were included and tested for training the models to improve the prediction across lakes, such as water level, turbidity, lake size, temporal window between the field sample and satellite image (a maximum of three to five days was established), etc. We will present some preliminary results, discuss the transferability of this innovative method to monitor relevant ecological attributes of high-altitude lakes, review key methodological challenges and highlight the implications of this methodology to support the study of human and environmental interactions in these endangered ecosystems.

Preliminary analyses reveal that the traditional empirical models that perform best are the ones based on blue and green bands. Current models could improve implementing novel artificial intelligence techniques.

This work is part of Smart EcoMountains, the Thematic Center on Mountain Ecosystems of LifeWatch-ERIC.

Abstract ID 272 | Date: 2022-09-14 17:45 – 17:47 | Type: Poster Presentation | Place: SOWI – Garden |

Liro, Maciej; Mikuś, Paweł; Wyżga, Bartłomiej

Macroplastic storage process in a mountain river channel has not yet been explored; however, its understanding is a prerequiste for identification of macroplastic accumulation hot-spots and evaluation of the related risks.

We determined the amounts of macroplastic debris deposited in the active channel of the gravel-bed Dunajec River, southern Poland. The study reach stored ~224 kg of macroplastic per 1 km of channel length, with 82.6% of the amount stored in/on wood jams that covered only 2.1% of the area of active river zone. On average, wood jams stored 9.5 plastic items/m² of active channel area, i.e. 32 times more than channel areas covered by non-woody vegetation and 95 times more than bare gravel surfaces. The average mass of macroplastic items trapped by wood jams was 3-4 times larger than those deposited in channel areas outside jams. On average, jams stored 113.2 g of macroplastic/m², with the amount exceeding 126 times the mass of macroplastic stored in areas overgrown with non-woody vegetation and 189 times that on bare gravel surfaces. We also found that macroplastic seen on the surface of wood jams represented 72.3% of its total amount trapped by jams. The proportion of inside jam-stored macroplastic debris increased linearly with jam volume (p = 0.007; R² = 0.57). These results demonstrate that wood jams trap a considerable proportion of macroplastic stored in the channel of mountain river and suggest that disintegration of such jams by flood flows may be an important source of remobilization of macroplastic during floods.

Abstract ID 777 | Date: 2022-09-14 17:47 – 17:49 | Type: Poster Presentation | Place: SOWI – Garden |

Aliste, Valentina; Núñez, Paloma; Schauwecker, Simone; Macdonell, Shelley

In Central Chile, annual precipitation is characterized by a large year-to-year variability and depends mostly on few storm events during winter. Precipitation that falls as snow at high elevations is one of the principal water sources for the region. The last decade was especially dry in Central Chile – the so-called central Chile megadrought. The extraordinarily dry conditions and the increased water consumption have led to a considerable stress of the water system. People living in high mountain areas are especially vulnerable to water scarcity. But scientists are not always aware of the concerns and needs of the local population, which makes it difficult to generate scientific knowledge in line with local knowledge.

The project Vecinos de las Nieves (Snow Neighbors) connects local community knowledge with water resource science to jointly study snow and rain dynamics in the mountains of the Coquimbo Region, Chile. Since 2018, we have collected fresh snow data in collaboration with community members who live and/or work in the mountainous sector (above 1,390 m asl). Following each snowfall, the volunteers measure the physical-chemical characteristics of the snow on the ground. In total, 13 precipitation events were documented, with up to 29 cm at the highest observation site (3150 m asl.). In 2021, we expanded the initiative, and created a network of primary schools and rural establishments in the mountains. This year, the work team conducted face-to-face interviews with the participants to analyze their learning experiences and observations, opening a space for reflection on the megadrought and its impacts.

Most participants have observed drier conditions in their environment during the last years, with fewer snow events compared to previous years. They show growing concern about the water availability in the future. Also, some participants mentioned water allocation conflicts in their communities due to decreasing precipitation and increasing water use in the last years. In response to this, some participants are developing adaptation strategies.

In conclusion, the program has generated new scientific understanding of snow and rain processes during the four winter periods, as well as connected isolated communities in the pursuit of science, and has highlighted the importance to connect local knowledge and interdisciplinary research to understand snow dynamics and water availability in this area.

Abstract ID 894 | Date: 2022-09-14 17:49 – 17:51 | Type: Poster Presentation | Place: SOWI – Garden |

Villar-Argaiz, Manuel (1); Medina-Sánchez, Juan Manuel (1); Fajardo-Merlo, María Del Carmen (2); Muñoz Pedraza, Antonio Gonzalo (2); Sofos Neveros, Ernesto (2); Biddanda, Bopaiah (3); Camacho-Páez, José (1); Morales-Jimenez, David (1)

Environmental warming is the most conspicuous and relevant effect of ongoing climate change. However, the increase of a lake water temperature is not easily predictable as warming effects may co-occur with a myriad of other confounding climate factors such as changes in precipitation and droughts or changes in lake morphological features – effects that are not easy to untangle. Based on long-term time-series observations, we explore the increase in water temperature of four small high-mountain lakes in the Sierra Nevada (southern Spain) with different depth and geomorphometric features. Our hypotheses are that warming is occurring in all the lakes of this high-mountain region, summer water-column stability is increasing, duration of ice-cover period is decreasing, and that inter-lake differences are due to variation in lake depth and local geomorphology. Utilizing high-frequency in situ temperature data from years 2009 (Lake La Caldera and Laguna Larga) or 2011 (Río Seco and Aguas Verdes) to 2021, and multiple discrete measurements as far back as 1984, we will test the above hypotheses, describe the findings, and discuss their relevance to the ecology of mountain lakes in the Sierra Nevada.

This work is part of Smart EcoMountains, the Thematic Center on Mountain Ecosystems of LifeWatch-ERIC.

Abstract ID 806 | Date: 2022-09-14 17:51 – 17:53 | Type: Poster Presentation | Place: SOWI – Garden |

Biskop, Sophie (1); Fink, Manfred (1,2); Kunze, Sabrina (1); Leiterer, Reik (3,4); Sassik, Bernhard (4); Schmidt, Henrik (1)

The Spanish Pyrenees provide a substantial part of the water resources to sustain environmental and human water demands in the semi-arid downstream lowlands, by storing water in winter and releasing it during the dry warm summer season. However, water scarcity is already a widespread problem and climate change is increasing snow droughts and shifting spatio-temporal patterns of snow accumulation and ablation (including a shift from snow to rain, rising snow lines, snowpack decline, earlier snowmelt). These snow distribution changes will likely have serious water supply consequences for multiple sectors (e.g. hydropower, agriculture, tourism, etc.). Understanding spatial heterogeneity of snowpack distribution and temporal variation in snow accumulation and melt dynamics can help us to advance our understanding of the processes controlling streamflow generation across scales and to improve hydrological predictions for various water users. In this context, this study focuses on two main objectives:

• Linking hydrological simulations and satellite-derived high-resolution snow estimations in a hybrid model for improved hydrological predictions. Using the Jena Adaptable Modelling System (JAMS), a software framework for component-based development of environmental models, novel satellite-derived high-resolution COSMOS20 snow products (snow cover, snow depth and snow water equivalent) are integrated into the spatially-distributed, physically-based J2000 model.

• Assessment of the impacts of snow accumulation and ablation patterns on water availability from a multi-scale perspective. By applying the hybrid model, the response of streamflow to spatio-temporal variations of snow distribution is simulated and runoff components are quantified across scales ranging from small headwater catchments of hydropower reservoirs up to upper meso-scale basins of large reservoirs used for controlling water flows downstream (flood control, irrigation canals, etc.). Thereby, the influence of different proportions of snow-dominated areas on the runoff dynamics is investigated.

The modelling outputs support the development of appropriate climate adaptation and mitigation strategies, aiming to achieve a sustainable water management across all sectors. This study highlights the potential benefits of the synergy between satellite-derived high-resolution snow estimations and hydrological modelling to examine how mountain snow accumulation and ablation patterns vary through space and time and to investigate quantitatively cross-scale effects of snow distribution variations on water resources availability.

Abstract ID 274 | Date: 2022-09-14 17:53 – 17:55 | Type: Poster Presentation | Place: SOWI – Garden |

Liro, Maciej (1); Zielonka, Anna (2); Grodzińska-Jurczak, Małgorzata (3); Liro, Justyna (2); Kiss, Tímea (4); Van Emmerik, Tim (5); Wyżga, Bartłomiej (1)

Data on spatial distribution of mismanaged plastic waste along the river course is crucial to assessment the plastic input to the river system. Moreover, it is important for evaluation of related risks to biota, human health and aesthetic value of riverine landscape. So far, mountain rivers, not directly connected with the oceans, have not been investigated on a on plastic pollution, which make an evaluation of the above risk in these high biodiversity ecosystems difficult.

Here, we employ spatial analysis utilizing publicly available databases of vector-based hydrography and raster dataset of modelled mismanaged plastic waste (MPW)) to provide first ever estimation on spatial distribution of MPW along all rivers and streams (in total 175669 kilometers) draining the Carpathians Mountains (Central-East Europe). To calculate MPW distribution along studied rivers we intersected pixel values of MPW layer with vector layer of watercourses and other datasets (e.g., DEM). The highest MPW was found along the watercourses of 5th and 6th order (Strahler) (872 and 680 t/yr. respectively). The highest proportion of MPW hot-spots (MPW>5000 t/yr.) along watercourses occur in Romania (3392 km) and Poland (2309 km). Watercourses within Baltic Sea basin (11.1 % of all studied watercourses) flow through the Carpathian regions with higher MPW (620 t/yr.) than these from the Black Sea basin (88.3 % of all studied watercourses) (60 t/yr.). MPW varied between the analyzed catchments of main Carpathian rivers, reaching the highest values in the west-north part of the region (e.g., Oder River (0.7% of studied watercourses) (908.8 t/yr.) and Vistula River catchments (2.6% of studied watercourses) (605 t/yr.). MPW also varied among the watercourses flowing through the areas of different nature protection types (national, regional, international), reaching the highest value in areas protected on national level (29.5 % of all studied watercourses).

We suggest that mountainous rivers may considerably contribute to the plastic pollution of rivers. Though these areas are not densely inhabited, the waste management in these areas is difficult due the terrain conditions, besides it is not profitable to collect the waste in these areas, therefore the waste is often illegally or improperly deposited. Our results can be used as an applying material to decision makers on a rapid need to minimize MPW in local and regional scale of Carpathian region. Such a requirement should comprise actions towards increasing public eco-awareness as well as withdrawing appropriate legal restrictions.

Abstract ID 630 | Date: 2022-09-14 17:55 – 17:57 | Type: Poster Presentation | Place: SOWI – Garden |

Charonnat, Bastien (1); Baraer, Michel (1); Valence, Eole (1,2); Mckenzie, Jeffrey (2)

The alpine cryosphere is retreating at a high rate under the ongoing changes in climate, leading to modifications in the hydrological behaviour of subarctic glacierized valleys. These catchments not only feature bare ice glaciers but also different cryospheric elements (debris-covered glaciers, rock glaciers, permafrost, buried ice…) that behave as one complex hydrological system. Thus, there is a need in characterizing poorly known cryo-hydrological processes and interactions. A glacierized catchment in Grizzly Creek’s valley, located in St. Elias Mts (Yukon, Canada), groups every one of the cryospheric elements cited above. This configuration leads us to consider it as a favourable site for studying these elements, their hydrological role and interactions, and their evolution in a climate change context. A conceptual model of the hydrological system describes processes and interactions from the head to the outlet, but the over-representation of undersurface processes makes its conception complicated. Thus, some surface cryo-hydrological phenomena (aufeis formation, supra-rock glacier lakes, temporary outflows…) are analyzed and monitored to infer the internal structure of the system and the interactions between the different elements. Complementary methods (time-lapse imagery, hydro-meteorological and hydrochemical analysis, photogrammetry, GPR surveys…) are used to analyze the occurrence of these phenomena and their links with the rest of the system under climate change. Therefore, it allows us to draft a conceptualization of the system and to spot tipping points in cryosphere retreat that would affect its hydrological behaviour and its annual discharge. It is mandatory to point towards an assessment of the impact of cryospheric changes on future water resources of foreland regions.