The Canadian Rockies region has experienced substantial climate warming, snowpack decline and gla... more The Canadian Rockies region has experienced substantial climate warming, snowpack decline and glacier retreat, and is anticipated to undergo further warming due to anthropogenic climate change. To better understand the sensitivity of snow processes to warming, a spatially detailed physically based snow hydrology model was constructed for Marmot Creek Research Basin, Alberta, Canada using the Cold Regions Hydrological Modelling platform and used to assess the snow hydrology of a high elevation alpine environment and two medium elevation environments, one densely forested and the other a small forest clearing. Processes modelled include precipitation phase, snow redistribution by wind, snow interception and canopy unloading, sublimation from blowing, intercepted and surface snow, and energy budget snowmelt. The model was run with current and then with perturbed climates with increased temperature, holding relative humidity constant. Increasing temperatures increase the rainfall fracti...
Interactions between the land surface and the atmosphere play essential roles in hydrological var... more Interactions between the land surface and the atmosphere play essential roles in hydrological variations at local scales. Variations of regional climate patterns over preceding years have key effects on the seasonal water and moisture conditions in the following year. The linkage between regional climate and local hydrology is challenging due to scale differences, both spatially and temporally. In this study, multiple hydroclimatic phases were identified to relate climatic teleconnection patterns to hydrological processes in a small headwater basin within Reynolds Creek Experiment Watershed, Idaho, USA. A singular spectrum analysis and a combination of hydrological observations and outputs from a physically based hydrological model were used for this purpose. Results showed that a positive phase of North Atlantic Oscillation (NAO) is more influential than a positive phase of the Pacific North American (PNA) pattern on the observed annual runoff and the modeled rain on snow runoff in the study area. Specifically, we found a 43% and 26% shift below normal in annual runoff and rain on snow runoff from NAO and a 29% and 9% below normal from PNA. More frequent rain on snow events were observed under a positive phase of Antarctic Oscillation, leading to a 45% increase in the rain on snow runoff, which accounts for one-third of the mean annual runoff. A high runoff-to-precipitation ratio was observed in the study area under negative phases of Arctic Oscillation and Sea Surface Temperature in the Nino 3.4 region of the Equatorial Pacific Ocean. A switch in the phase of the teleconnection patterns of NAO and PNA in 2012 was concomitant with a transition from wet to dry conditions in the basin, suggesting the importance of the regional teleconnections in affecting snow and runoff regimes at local scales. The identified hydroclimatic phases can be implemented in operational models to improve uncertainties in hydrological forecasts, climate projections, and water resources planning.
A new flow for Canadian young hydrologists: Key scientific challenges addressed by research cultu... more A new flow for Canadian young hydrologists: Key scientific challenges addressed by research cultural shiftsCaroline Aubry-Wake1, Lauren D. Somers2,3, Hayley Alcock4, Aspen M. Anderson5, Amin Azarkhish6, Samuel Bansah7, Nicole M. Bell8, Kelly Biagi9, Mariana Castaneda-Gonzalez10, Olivier Champagne9, Anna Chesnokova10, Devin Coone6, Tasha-Leigh J. Gauthier11, Uttam Ghimire6, Nathan Glas6, Dylan M. Hrach11, Oi Yin Lai14, Pierrick Lamontagne-Halle3, Nicolas R. Leroux1, Laura Lyon3, Sohom Mandal12, Bouchra R. Nasri13, Natasa Popovic11, Tracy. E. Rankin14, Kabir Rasouli15, Alexis Robinson16, Palash Sanyal17, Nadine J. Shatilla9, 18, Brandon Van Huizen11, Sophie Wilkinson9, Jessica Williamson11, Majid Zaremehrjardy191 Centre for Hydrology, University of Saskatchewan, Saskatoon, SK, Canada2 Civil and Environmental Engineering, Massachusetts Institute of Technology, MA, USA3 Department of Earth and Planetary Sciences, McGill University, Montreal QC4 Department of Natural Resource Science, McGill University, Montreal, QC, Canada5 Department of Earth Sciences, Simon Fraser University, Burnaby, BC, Canada6 School of Engineering, University of Guelph, Ontario, ON, Canada7 Department of Geological Sciences, University of Manitoba, Winnipeg, Canada8 Centre for Water Resources Studies, Department of Civil & Resource Engineering, Dalhousie University, Halifax, NS, Canada9 School of Geography and Earth Sciences, McMaster University, Hamilton, ON, Canada.10 Department of Construction Engineering, Ecole de technologie superieure, Montreal, QC, Canada11 Department of Geography & Environmental Management, University of Waterloo, Waterloo, ON, Canada12 Department of Geography and Environmental Studies, Ryerson University, Toronto, ON, Canada13 Department of Mathematics and Statistics, McGill University, Montreal, Qc, Canada14 Geography Department, McGill University, Montreal, QC, Canada15 Meteorological Service of Canada, Environment and Climate Change Canada, Dorval, QC, Canada16 Department of Geography and Planning, University of Toronto, Toronto, ON17 Global Institute for Water Security, University of Saskatchewan.18 Lorax Environmental Services Ltd, Vancouver, BC, Canada.19 Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, AB, Canada
<p>Arctic rivers’ flow regime has changed under climate c... more <p>Arctic rivers’ flow regime has changed under climate change and its consequences on melting glaciers, thawing permafrost, and precipitation patterns. Reservoirs, hydro-power sites, and water diversions have also changed flow regimes in the Arctic. The flow regime alteration in the Arctic rivers has a strong influence on the conservation and sustainability of the native biodiversity of the riverine ecosystem. The main objective of this paper is to evaluate changes in the (1) magnitude of monthly stream flows, (2) magnitude and duration of annual maxima and minima flows, (3) timing of annual maxima and minima, (4) frequency and duration of high and low pulses, and (5) rate and frequency of daily flows in seven major Arctic Rivers. The analyses provide an important basis to characterize and understand the influence of climate change and anthropogenic activities on the flow regimes in the Arctic. Streamflow observations were obtained from the outlet of the Lena, Yenisei, Kolyma, Ob (Russia), Yukon (USA and Canada), Mackenzie (Canada), and Tana (Norway and Finland) rivers in this study. These rivers are main freshwater suppliers for Arctic Ocean. Of these, five have been regulated and two are considered pristine rivers. In addition, the impact of 16 reservoirs on flow regime in the headwaters and tributaries of Lena, Yenisei, Mackenzie, and Kolyma were evaluated. The annual flow showed an increasing trend in all rivers and with a statistically significant level in Yenisei, Lena, and Mackenzie. Our results also indicated that changes in the observed flow regimes at the outlet stations vary from low to incipient level. Out of 16 reservoirs that were analyzed for flow regimes changes, construction of Krasnoyarsk and Shushenskaya dams on the Yenisei River showed the highest impact on flow regime and flow regime alteration was classified as severe in this river.</p>
The 1911-2010 variability in monthly runoff and the effect of 1995-2005 summer water temperatures... more The 1911-2010 variability in monthly runoff and the effect of 1995-2005 summer water temperatures in a highly productive salmon system, the Fraser River Basin (FRB) of British Columbia, Canada are explored. Hydrometric data from 141 FRB gauges provide variations in monthly runoff including their extremes and months of occurrences, as well as trends in their variability. Stream temperatures and their relationships to runoff are also assessed. There is a gradual increase of monthly runoff ranges from the central plateau of the FRB towards higher altitudes with maxima in glacier-fed alpine streams. Maximum and minimum monthly runoff across the FRB typically occur during May-June and February, respectively. There is a tendency towards greater FRB variability in July runoff. Water temperatures show high variability in the unregulated North and South Thompson rivers and low variability in the regulated Nechako River. FRB low flows are associated with higher water temperatures, while high flows are associated with cooler ones, both of which may have a negative impact on salmon. Impacts de la variabilité et des tendances des débits et la température de l'eau sur la migration du saumon dans le bassin du fleuve Fraser au Canada Résumé Nous avons étudié la variabilité de l'écoulement mensuel entre 1911 et 2010 et des températures de l'eau en été entre 1995 et 2005 dans un système très productif en saumon, le bassin du fleuve Fraser (BFF) en Colombie-Britannique (Canada). Les données hydrométriques de 141 stations fournissent les variations des débits mensuels, y compris leurs extrêmes et leurs mois d'occurence, ainsi que les tendances de leur variabilité. La température de l'eau et ses relations avec les débits a également été examinée. On observe une augmentation progressive des gammes de l'écoulement mensuel depuis le plateau central du BFF vers les altitudes plus élevées avec des maximums dans les rivières alpines alimentées par les glaciers. Le débit mensuel maximum dans le BFF est généralement observé en mai-juin et le minimum en février. Il y a une tendance à une plus grande variabilité dans les débits de juillet. La température de l'eau montre une grande variabilité dans les rivières Thompson Nord et Sud, non régularisées, et une faible variabilité dans la rivière Nechako qui est régularisée. Les faibles débits du bassin sont associés à des températures élevées de l'eau, tandis que les débits les plus importants sont associés à des températures plus faibles, les deux pouvant avoir un impact négatif sur le saumon. Mots clefs saumon ; température de l'eau ; neige ; changement climatique ; bassin du fleuve Fraser ; Colombie-Britannique ; Canada
The frost table depth is a critical state variable for hydrological modelling in cold regions as ... more The frost table depth is a critical state variable for hydrological modelling in cold regions as frozen ground controls runoff generation, subsurface water storage and the permafrost regime. Calculation of the frost table depth is typically performed using a modified version of the Stefan equation, which is driven with the ground surface temperature. Ground surface temperatures have usually been estimated as linear functions of air temperature, referred to as 'n-factors' in permafrost studies. However, these linear functions perform poorly early in the thaw season and vary widely with slope, aspect and vegetation cover, requiring site-specific calibration. In order to improve estimation of the ground surface temperature and avoid site-specific calibration, an empirical radiative-conductive-convective (RCC) approach is proposed that uses air temperature, net radiation and antecedent frost table position as driving variables. The RCC algorithm was developed from forested and open sites on the eastern slope of the Coastal Mountains in southern Yukon, Canada, and tested at a high-altitude site in the Canadian Rockies, and a peatland in the southern Northwest Territories. The RCC approach performed well in a variety of land types without any local calibration and particularly improved estimation of ground temperature compared with linear functions during the first month of the thaw season, with mean absolute errors <2 °C in seven of the nine sites tested. An example of the RCC approach coupled with a modified Stefan thaw equation suggests a capability to represent frozen ground conditions that can be incorporated into hydrological and permafrost models of cold regions.
Hydrological processes are widely understood to be sensitive to changes in climate, but the effec... more Hydrological processes are widely understood to be sensitive to changes in climate, but the effects of con-comitant changes in vegetation and soils have seldom been considered in snow-dominated mountain basins. The response of mountain hydrology to vegetation/soil changes in the present and a future climate was modeled in three snowmelt-dominated mountain basins in the North Amer-ican Cordillera. The models developed for each basin using the Cold Regions Hydrological Modeling platform employed current and expected changes to vegetation and soil parameters and were driven with recent and perturbed high-altitude meteorological observations. Monthly perturbations were calculated using the differences in outputs between the present-and a future-climate scenario from 11 regional climate models. In the three basins, future climate change alone decreased the modeled peak snow water equivalent (SWE) by 11 %-47 % and increased the modeled evapotranspiration by 14 %-20 %. However, including future changes in vegetation and soil for each basin changed or reversed these climate change outcomes. In Wolf Creek in the Yukon Territory, Canada, a statistically insignificant increase in SWE due to vegetation increase in the alpine zone was found to offset the statistically significant decrease in SWE due to climate change. In Marmot Creek in the Canadian Rockies, the increase in annual runoff due to the combined effect of soil and climate change was statistically significant, whereas their individual effects were not. In the relatively warmer Reynolds Mountain in Idaho, USA, vegetation change alone decreased the annual runoff volume by 8 %, but changes in soil, climate , or both did not affect runoff. At high elevations in Wolf and Marmot creeks, the model results indicated that vegeta-tion/soil changes moderated the impact of climate change on peak SWE, the timing of peak SWE, evapotranspiration, and the annual runoff volume. However, at medium elevations, these changes intensified the impact of climate change, further decreasing peak SWE and sublimation. The hydrological impacts of changes in climate, vegetation, and soil in mountain environments were similar in magnitude but not consistent in direction for all biomes; in some combinations, this resulted in enhanced impacts at lower elevations and latitudes and moderated impacts at higher elevations and latitudes.
Journal of Hydrologic Engineering / Volume 24 Issue 12
Forecasting precipitation remains challenging because of its large spatial and temporal variabili... more Forecasting precipitation remains challenging because of its large spatial and temporal variability, and the uncertainty in precipitation forecast leads to an important source of uncertainty in the prediction of other components of a hydrological system. In this study, in order to forecast subseasonal precipitation and better characterize the temporal variability of precipitation, a hybrid precipitation forecast model was developed based on (1) temporal clustering of subseasonal precipitation; and (2) coupling an improved seasonal autoregressive integrated moving average (ISARIMA) model to an artificial neural network (ANN) model to take the advantages of both models and capture precipitation persistence and statistics in each cluster. The performance of the proposed model was compared against different variations of conventional statistical models in the Rasht station with a humid climate and Gorgan station with a Mediterranean climate, both located south of the Caspian Sea in northern Iran. The model evaluation criteria indicated that the hybrid model can remarkably improve forecast accuracy. The root-mean square error score of the forecasted precipitation by the hybrid model against observations decreased 48% and 24% in the Rasht and Gorgan stations, respectively, when compared with the seasonal autoregressive integrated moving average (SARIMA) model and the index of agreement increased 32% and 17%, respectively, when compared with the ANN models. The proposed hybrid model can be a useful tool for forecasting subseasonal precipitation in humid and arid climates with persistent and nonpersistent precipitation patterns.
How mountain hydrology at different elevations will respond to climate change is a challenging qu... more How mountain hydrology at different elevations will respond to climate change is a challenging question of great importance to assessing changing water resources. Here, three North American Cordilleran snow-dominated basins—Wolf Creek, Yukon; Marmot Creek, Alberta; and Reynolds Mountain East, Idaho—each with good meteorological and hydrological records, were modeled using the physically based, spatially distributed Cold Regions Hydrological Model. Model performance was verified using field observations and found adequate for diagnostic analysis. To diagnose the effects of future climate, the monthly temperature and precipitation changes projected for the future by 11 regional climate models for the mid-twenty-first century were added to the observed meteorological time series. The modeled future was warmer and wetter, increasing the rainfall fraction of precipitation and shifting all three basins toward rainfall–runoff hydrology. This shift was largest at lower elevations and in the relatively warmer Reynolds Mountain East. In the warmer future, there was decreased blowing snow transport, snow interception and sublimation, peak snow accumulation, and melt rates, and increased evapotranspiration and the duration of the snow-free season. Annual runoff in these basins did not change despite precipitation increases, warming, and an increased prominence of rainfall over snowfall. Reduced snow sublimation offset reduced snowfall amounts, and increased evapotranspiration offset increased rainfall amounts. The hydrological uncertainty due to variation among climate models was greater than the predicted hydrological changes. While the results of this study can be used to assess the vulnerability and resiliency of water resources that are dependent on mountain snow, stakeholders and water managers must make decisions under considerable uncertainty, which this paper illustrates.
This paper provides an early career researchers (ECRs) perspective on major challenges and opport... more This paper provides an early career researchers (ECRs) perspective on major challenges and opportunities that arise in the study and understanding of, and the provision of regional information for Climate, Weather and Hydrological (CWH) extreme events. This perspective emerged from the discussions of the early career 3-day Young Earth System Scientists - Young Hydrologic Society (YESS-YHS) workshop, which was conjointly held with the Global Energy and Water Exchanges (GEWEX) Open Science Conference. In this paper we discuss three possible ways forward in the field: a stronger interaction between Earth system scientists and users, a collaborative modeling approach between the different modeling communities, and an increased use of unconventional data sources in scientific studies. This paper also demonstrates the important role of ECRs in embracing the above outlined pathways and addressing the long-standing challenges in the field. YESS and YHS networks encourage the global community to support and streng then their involvement with ECR communities to advance the field of interdisciplinary Earth system science in the upcoming years to decades.
A set of hydrometeorological data is presented in this paper, which can be used to characterize t... more A set of hydrometeorological data is presented in this paper, which can be used to characterize the hydrometeorology and climate of a subarctic mountain basin and has proven particularly useful for forcing hydrological models and assessing their performance in capturing hydrological processes in subarctic alpine environments. The forcing dataset includes daily precipitation, hourly air temperature, humidity, wind, solar and net radiation, soil temperature, and geographical information system data. The model performance assessment data include snow depth and snow water equivalent, streamflow, soil moisture, and water level in a groundwater well. This dataset was recorded at different elevation bands in Wolf Creek Research Basin, near Whitehorse, Yukon Territory, Canada, representing forest, shrub tundra, and alpine tundra biomes from 1993 through 2014. Measurements continue through 2018 and are planned for the future at this basin and will be updated to the data website. The database presented and described in this article is available for download at https://doi.org/10.20383/101.0113.
ABSTRACT http://onlinelibrary.wiley.com/doi/10.1002/hyp.10587/abstract There is great interest in... more ABSTRACT http://onlinelibrary.wiley.com/doi/10.1002/hyp.10587/abstract There is great interest in ascertaining the degree of climate change necessary to induce substantial changes in snow accumulation and ablation processes in mountain headwater catchments. Therefore, the response of mountain snow hydrology to changes in air temperature and precipitation was examined by simulating a perturbed climate in Reynolds Mountain East (RME), a headwater catchment with a cool mountain climate in Idaho, USA. The Cold Regions Hydrological Model was used to calculate snow accumulation, wind redistribution by blowing snow, interception by forest canopies, sublimation and melt for 25 seasons in RME. The uncalibrated simulations of the highly redistributed SWE compared well to measurements. Results showed that with concomitant occurrence of warming (5°C) and precipitation change (±20%) in RME, the peak seasonal snow accumulation decreased by 84-90%, snowmelt decreased 51-79%, rainfall to total precipitation ratio increased from 30% to 78%, and overwinter blowing snow transport and sublimation losses from intercepted snow, the snow surface and blowing snow decreased dramatically. Warming causes an increase in inter-water year snowcover variability but a decrease in spatial snow accumulation variability. When warming exceeded 1°C and a precipitation increased by less than 20%, the peak snow accumulation declined dramatically. The results contrast with those from further north along the North American Cordillera in Yukon, Canada, where the impacts of similar warming on alpine snow can be partly compensated for by concomitant increases in precipitation of less than 20%.
The Canadian Rockies region has experienced substantial climate warming, snowpack decline and gla... more The Canadian Rockies region has experienced substantial climate warming, snowpack decline and glacier retreat, and is anticipated to undergo further warming due to anthropogenic climate change. To better understand the sensitivity of snow processes to warming, a spatially detailed physically based snow hydrology model was constructed for Marmot Creek Research Basin, Alberta, Canada using the Cold Regions Hydrological Modelling platform and used to assess the snow hydrology of a high elevation alpine environment and two medium elevation environments, one densely forested and the other a small forest clearing. Processes modelled include precipitation phase, snow redistribution by wind, snow interception and canopy unloading, sublimation from blowing, intercepted and surface snow, and energy budget snowmelt. The model was run with current and then with perturbed climates with increased temperature, holding relative humidity constant. Increasing temperatures increase the rainfall fracti...
Interactions between the land surface and the atmosphere play essential roles in hydrological var... more Interactions between the land surface and the atmosphere play essential roles in hydrological variations at local scales. Variations of regional climate patterns over preceding years have key effects on the seasonal water and moisture conditions in the following year. The linkage between regional climate and local hydrology is challenging due to scale differences, both spatially and temporally. In this study, multiple hydroclimatic phases were identified to relate climatic teleconnection patterns to hydrological processes in a small headwater basin within Reynolds Creek Experiment Watershed, Idaho, USA. A singular spectrum analysis and a combination of hydrological observations and outputs from a physically based hydrological model were used for this purpose. Results showed that a positive phase of North Atlantic Oscillation (NAO) is more influential than a positive phase of the Pacific North American (PNA) pattern on the observed annual runoff and the modeled rain on snow runoff in the study area. Specifically, we found a 43% and 26% shift below normal in annual runoff and rain on snow runoff from NAO and a 29% and 9% below normal from PNA. More frequent rain on snow events were observed under a positive phase of Antarctic Oscillation, leading to a 45% increase in the rain on snow runoff, which accounts for one-third of the mean annual runoff. A high runoff-to-precipitation ratio was observed in the study area under negative phases of Arctic Oscillation and Sea Surface Temperature in the Nino 3.4 region of the Equatorial Pacific Ocean. A switch in the phase of the teleconnection patterns of NAO and PNA in 2012 was concomitant with a transition from wet to dry conditions in the basin, suggesting the importance of the regional teleconnections in affecting snow and runoff regimes at local scales. The identified hydroclimatic phases can be implemented in operational models to improve uncertainties in hydrological forecasts, climate projections, and water resources planning.
A new flow for Canadian young hydrologists: Key scientific challenges addressed by research cultu... more A new flow for Canadian young hydrologists: Key scientific challenges addressed by research cultural shiftsCaroline Aubry-Wake1, Lauren D. Somers2,3, Hayley Alcock4, Aspen M. Anderson5, Amin Azarkhish6, Samuel Bansah7, Nicole M. Bell8, Kelly Biagi9, Mariana Castaneda-Gonzalez10, Olivier Champagne9, Anna Chesnokova10, Devin Coone6, Tasha-Leigh J. Gauthier11, Uttam Ghimire6, Nathan Glas6, Dylan M. Hrach11, Oi Yin Lai14, Pierrick Lamontagne-Halle3, Nicolas R. Leroux1, Laura Lyon3, Sohom Mandal12, Bouchra R. Nasri13, Natasa Popovic11, Tracy. E. Rankin14, Kabir Rasouli15, Alexis Robinson16, Palash Sanyal17, Nadine J. Shatilla9, 18, Brandon Van Huizen11, Sophie Wilkinson9, Jessica Williamson11, Majid Zaremehrjardy191 Centre for Hydrology, University of Saskatchewan, Saskatoon, SK, Canada2 Civil and Environmental Engineering, Massachusetts Institute of Technology, MA, USA3 Department of Earth and Planetary Sciences, McGill University, Montreal QC4 Department of Natural Resource Science, McGill University, Montreal, QC, Canada5 Department of Earth Sciences, Simon Fraser University, Burnaby, BC, Canada6 School of Engineering, University of Guelph, Ontario, ON, Canada7 Department of Geological Sciences, University of Manitoba, Winnipeg, Canada8 Centre for Water Resources Studies, Department of Civil & Resource Engineering, Dalhousie University, Halifax, NS, Canada9 School of Geography and Earth Sciences, McMaster University, Hamilton, ON, Canada.10 Department of Construction Engineering, Ecole de technologie superieure, Montreal, QC, Canada11 Department of Geography & Environmental Management, University of Waterloo, Waterloo, ON, Canada12 Department of Geography and Environmental Studies, Ryerson University, Toronto, ON, Canada13 Department of Mathematics and Statistics, McGill University, Montreal, Qc, Canada14 Geography Department, McGill University, Montreal, QC, Canada15 Meteorological Service of Canada, Environment and Climate Change Canada, Dorval, QC, Canada16 Department of Geography and Planning, University of Toronto, Toronto, ON17 Global Institute for Water Security, University of Saskatchewan.18 Lorax Environmental Services Ltd, Vancouver, BC, Canada.19 Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, AB, Canada
&amp;lt;p&amp;gt;Arctic rivers&amp;amp;#8217; flow regime has changed under climate c... more &amp;lt;p&amp;gt;Arctic rivers&amp;amp;#8217; flow regime has changed under climate change and its consequences on melting glaciers, thawing permafrost, and precipitation patterns. Reservoirs, hydro-power sites, and water diversions have also changed flow regimes in the Arctic. The flow regime alteration in the Arctic rivers has a strong influence on the conservation and sustainability of the native biodiversity of the riverine ecosystem. The main objective of this paper is to evaluate changes in the (1) magnitude of monthly stream flows, (2) magnitude and duration of annual maxima and minima flows, (3) timing of annual maxima and minima, (4) frequency and duration of high and low pulses, and (5) rate and frequency of daily flows in seven major Arctic Rivers. The analyses provide an important basis to characterize and understand the influence of climate change and anthropogenic activities on the flow regimes in the Arctic. Streamflow observations were obtained from the outlet of the Lena, Yenisei, Kolyma, Ob (Russia), Yukon (USA and Canada), Mackenzie (Canada), and Tana (Norway and Finland) rivers in this study. These rivers are main freshwater suppliers for Arctic Ocean. Of these, five have been regulated and two are considered pristine rivers. In addition, the impact of 16 reservoirs on flow regime in the headwaters and tributaries of Lena, Yenisei, Mackenzie, and Kolyma were evaluated. The annual flow showed an increasing trend in all rivers and with a statistically significant level in Yenisei, Lena, and Mackenzie. Our results also indicated that changes in the observed flow regimes at the outlet stations vary from low to incipient level. Out of 16 reservoirs that were analyzed for flow regimes changes, construction of Krasnoyarsk and Shushenskaya dams on the Yenisei River showed the highest impact on flow regime and flow regime alteration was classified as severe in this river.&amp;lt;/p&amp;gt;
The 1911-2010 variability in monthly runoff and the effect of 1995-2005 summer water temperatures... more The 1911-2010 variability in monthly runoff and the effect of 1995-2005 summer water temperatures in a highly productive salmon system, the Fraser River Basin (FRB) of British Columbia, Canada are explored. Hydrometric data from 141 FRB gauges provide variations in monthly runoff including their extremes and months of occurrences, as well as trends in their variability. Stream temperatures and their relationships to runoff are also assessed. There is a gradual increase of monthly runoff ranges from the central plateau of the FRB towards higher altitudes with maxima in glacier-fed alpine streams. Maximum and minimum monthly runoff across the FRB typically occur during May-June and February, respectively. There is a tendency towards greater FRB variability in July runoff. Water temperatures show high variability in the unregulated North and South Thompson rivers and low variability in the regulated Nechako River. FRB low flows are associated with higher water temperatures, while high flows are associated with cooler ones, both of which may have a negative impact on salmon. Impacts de la variabilité et des tendances des débits et la température de l'eau sur la migration du saumon dans le bassin du fleuve Fraser au Canada Résumé Nous avons étudié la variabilité de l'écoulement mensuel entre 1911 et 2010 et des températures de l'eau en été entre 1995 et 2005 dans un système très productif en saumon, le bassin du fleuve Fraser (BFF) en Colombie-Britannique (Canada). Les données hydrométriques de 141 stations fournissent les variations des débits mensuels, y compris leurs extrêmes et leurs mois d'occurence, ainsi que les tendances de leur variabilité. La température de l'eau et ses relations avec les débits a également été examinée. On observe une augmentation progressive des gammes de l'écoulement mensuel depuis le plateau central du BFF vers les altitudes plus élevées avec des maximums dans les rivières alpines alimentées par les glaciers. Le débit mensuel maximum dans le BFF est généralement observé en mai-juin et le minimum en février. Il y a une tendance à une plus grande variabilité dans les débits de juillet. La température de l'eau montre une grande variabilité dans les rivières Thompson Nord et Sud, non régularisées, et une faible variabilité dans la rivière Nechako qui est régularisée. Les faibles débits du bassin sont associés à des températures élevées de l'eau, tandis que les débits les plus importants sont associés à des températures plus faibles, les deux pouvant avoir un impact négatif sur le saumon. Mots clefs saumon ; température de l'eau ; neige ; changement climatique ; bassin du fleuve Fraser ; Colombie-Britannique ; Canada
The frost table depth is a critical state variable for hydrological modelling in cold regions as ... more The frost table depth is a critical state variable for hydrological modelling in cold regions as frozen ground controls runoff generation, subsurface water storage and the permafrost regime. Calculation of the frost table depth is typically performed using a modified version of the Stefan equation, which is driven with the ground surface temperature. Ground surface temperatures have usually been estimated as linear functions of air temperature, referred to as 'n-factors' in permafrost studies. However, these linear functions perform poorly early in the thaw season and vary widely with slope, aspect and vegetation cover, requiring site-specific calibration. In order to improve estimation of the ground surface temperature and avoid site-specific calibration, an empirical radiative-conductive-convective (RCC) approach is proposed that uses air temperature, net radiation and antecedent frost table position as driving variables. The RCC algorithm was developed from forested and open sites on the eastern slope of the Coastal Mountains in southern Yukon, Canada, and tested at a high-altitude site in the Canadian Rockies, and a peatland in the southern Northwest Territories. The RCC approach performed well in a variety of land types without any local calibration and particularly improved estimation of ground temperature compared with linear functions during the first month of the thaw season, with mean absolute errors <2 °C in seven of the nine sites tested. An example of the RCC approach coupled with a modified Stefan thaw equation suggests a capability to represent frozen ground conditions that can be incorporated into hydrological and permafrost models of cold regions.
Hydrological processes are widely understood to be sensitive to changes in climate, but the effec... more Hydrological processes are widely understood to be sensitive to changes in climate, but the effects of con-comitant changes in vegetation and soils have seldom been considered in snow-dominated mountain basins. The response of mountain hydrology to vegetation/soil changes in the present and a future climate was modeled in three snowmelt-dominated mountain basins in the North Amer-ican Cordillera. The models developed for each basin using the Cold Regions Hydrological Modeling platform employed current and expected changes to vegetation and soil parameters and were driven with recent and perturbed high-altitude meteorological observations. Monthly perturbations were calculated using the differences in outputs between the present-and a future-climate scenario from 11 regional climate models. In the three basins, future climate change alone decreased the modeled peak snow water equivalent (SWE) by 11 %-47 % and increased the modeled evapotranspiration by 14 %-20 %. However, including future changes in vegetation and soil for each basin changed or reversed these climate change outcomes. In Wolf Creek in the Yukon Territory, Canada, a statistically insignificant increase in SWE due to vegetation increase in the alpine zone was found to offset the statistically significant decrease in SWE due to climate change. In Marmot Creek in the Canadian Rockies, the increase in annual runoff due to the combined effect of soil and climate change was statistically significant, whereas their individual effects were not. In the relatively warmer Reynolds Mountain in Idaho, USA, vegetation change alone decreased the annual runoff volume by 8 %, but changes in soil, climate , or both did not affect runoff. At high elevations in Wolf and Marmot creeks, the model results indicated that vegeta-tion/soil changes moderated the impact of climate change on peak SWE, the timing of peak SWE, evapotranspiration, and the annual runoff volume. However, at medium elevations, these changes intensified the impact of climate change, further decreasing peak SWE and sublimation. The hydrological impacts of changes in climate, vegetation, and soil in mountain environments were similar in magnitude but not consistent in direction for all biomes; in some combinations, this resulted in enhanced impacts at lower elevations and latitudes and moderated impacts at higher elevations and latitudes.
Journal of Hydrologic Engineering / Volume 24 Issue 12
Forecasting precipitation remains challenging because of its large spatial and temporal variabili... more Forecasting precipitation remains challenging because of its large spatial and temporal variability, and the uncertainty in precipitation forecast leads to an important source of uncertainty in the prediction of other components of a hydrological system. In this study, in order to forecast subseasonal precipitation and better characterize the temporal variability of precipitation, a hybrid precipitation forecast model was developed based on (1) temporal clustering of subseasonal precipitation; and (2) coupling an improved seasonal autoregressive integrated moving average (ISARIMA) model to an artificial neural network (ANN) model to take the advantages of both models and capture precipitation persistence and statistics in each cluster. The performance of the proposed model was compared against different variations of conventional statistical models in the Rasht station with a humid climate and Gorgan station with a Mediterranean climate, both located south of the Caspian Sea in northern Iran. The model evaluation criteria indicated that the hybrid model can remarkably improve forecast accuracy. The root-mean square error score of the forecasted precipitation by the hybrid model against observations decreased 48% and 24% in the Rasht and Gorgan stations, respectively, when compared with the seasonal autoregressive integrated moving average (SARIMA) model and the index of agreement increased 32% and 17%, respectively, when compared with the ANN models. The proposed hybrid model can be a useful tool for forecasting subseasonal precipitation in humid and arid climates with persistent and nonpersistent precipitation patterns.
How mountain hydrology at different elevations will respond to climate change is a challenging qu... more How mountain hydrology at different elevations will respond to climate change is a challenging question of great importance to assessing changing water resources. Here, three North American Cordilleran snow-dominated basins—Wolf Creek, Yukon; Marmot Creek, Alberta; and Reynolds Mountain East, Idaho—each with good meteorological and hydrological records, were modeled using the physically based, spatially distributed Cold Regions Hydrological Model. Model performance was verified using field observations and found adequate for diagnostic analysis. To diagnose the effects of future climate, the monthly temperature and precipitation changes projected for the future by 11 regional climate models for the mid-twenty-first century were added to the observed meteorological time series. The modeled future was warmer and wetter, increasing the rainfall fraction of precipitation and shifting all three basins toward rainfall–runoff hydrology. This shift was largest at lower elevations and in the relatively warmer Reynolds Mountain East. In the warmer future, there was decreased blowing snow transport, snow interception and sublimation, peak snow accumulation, and melt rates, and increased evapotranspiration and the duration of the snow-free season. Annual runoff in these basins did not change despite precipitation increases, warming, and an increased prominence of rainfall over snowfall. Reduced snow sublimation offset reduced snowfall amounts, and increased evapotranspiration offset increased rainfall amounts. The hydrological uncertainty due to variation among climate models was greater than the predicted hydrological changes. While the results of this study can be used to assess the vulnerability and resiliency of water resources that are dependent on mountain snow, stakeholders and water managers must make decisions under considerable uncertainty, which this paper illustrates.
This paper provides an early career researchers (ECRs) perspective on major challenges and opport... more This paper provides an early career researchers (ECRs) perspective on major challenges and opportunities that arise in the study and understanding of, and the provision of regional information for Climate, Weather and Hydrological (CWH) extreme events. This perspective emerged from the discussions of the early career 3-day Young Earth System Scientists - Young Hydrologic Society (YESS-YHS) workshop, which was conjointly held with the Global Energy and Water Exchanges (GEWEX) Open Science Conference. In this paper we discuss three possible ways forward in the field: a stronger interaction between Earth system scientists and users, a collaborative modeling approach between the different modeling communities, and an increased use of unconventional data sources in scientific studies. This paper also demonstrates the important role of ECRs in embracing the above outlined pathways and addressing the long-standing challenges in the field. YESS and YHS networks encourage the global community to support and streng then their involvement with ECR communities to advance the field of interdisciplinary Earth system science in the upcoming years to decades.
A set of hydrometeorological data is presented in this paper, which can be used to characterize t... more A set of hydrometeorological data is presented in this paper, which can be used to characterize the hydrometeorology and climate of a subarctic mountain basin and has proven particularly useful for forcing hydrological models and assessing their performance in capturing hydrological processes in subarctic alpine environments. The forcing dataset includes daily precipitation, hourly air temperature, humidity, wind, solar and net radiation, soil temperature, and geographical information system data. The model performance assessment data include snow depth and snow water equivalent, streamflow, soil moisture, and water level in a groundwater well. This dataset was recorded at different elevation bands in Wolf Creek Research Basin, near Whitehorse, Yukon Territory, Canada, representing forest, shrub tundra, and alpine tundra biomes from 1993 through 2014. Measurements continue through 2018 and are planned for the future at this basin and will be updated to the data website. The database presented and described in this article is available for download at https://doi.org/10.20383/101.0113.
ABSTRACT http://onlinelibrary.wiley.com/doi/10.1002/hyp.10587/abstract There is great interest in... more ABSTRACT http://onlinelibrary.wiley.com/doi/10.1002/hyp.10587/abstract There is great interest in ascertaining the degree of climate change necessary to induce substantial changes in snow accumulation and ablation processes in mountain headwater catchments. Therefore, the response of mountain snow hydrology to changes in air temperature and precipitation was examined by simulating a perturbed climate in Reynolds Mountain East (RME), a headwater catchment with a cool mountain climate in Idaho, USA. The Cold Regions Hydrological Model was used to calculate snow accumulation, wind redistribution by blowing snow, interception by forest canopies, sublimation and melt for 25 seasons in RME. The uncalibrated simulations of the highly redistributed SWE compared well to measurements. Results showed that with concomitant occurrence of warming (5°C) and precipitation change (±20%) in RME, the peak seasonal snow accumulation decreased by 84-90%, snowmelt decreased 51-79%, rainfall to total precipitation ratio increased from 30% to 78%, and overwinter blowing snow transport and sublimation losses from intercepted snow, the snow surface and blowing snow decreased dramatically. Warming causes an increase in inter-water year snowcover variability but a decrease in spatial snow accumulation variability. When warming exceeded 1°C and a precipitation increased by less than 20%, the peak snow accumulation declined dramatically. The results contrast with those from further north along the North American Cordillera in Yukon, Canada, where the impacts of similar warming on alpine snow can be partly compensated for by concomitant increases in precipitation of less than 20%.
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Papers by Kabir Rasouli
Earth system scientists and users, a collaborative modeling approach between the different modeling communities, and an increased use of unconventional data sources in scientific studies. This paper also demonstrates the important role of ECRs in embracing the above outlined pathways and addressing the long-standing challenges in the field. YESS and YHS networks encourage the global community to
support and streng then their involvement with ECR communities to advance the field of interdisciplinary Earth system science in the upcoming years to decades.
Earth system scientists and users, a collaborative modeling approach between the different modeling communities, and an increased use of unconventional data sources in scientific studies. This paper also demonstrates the important role of ECRs in embracing the above outlined pathways and addressing the long-standing challenges in the field. YESS and YHS networks encourage the global community to
support and streng then their involvement with ECR communities to advance the field of interdisciplinary Earth system science in the upcoming years to decades.