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Seasonal streamflow forecasts provide key information for decision-making in sectors such as water supply management, hydropower generation, and irrigation scheduling. The predictability of streamflow on seasonal timescales relies heavily on initial hydrological conditions, such as the presence of snow and the availability of soil moisture. In high-latitude and high-altitude headwater basins in North America, snowmelt serves as the primary source of runoff generation. This study presents and evaluates a data-driven workflow for probabilistic seasonal streamflow forecasting in snow-fed river basins across North America (Canada and the USA). The workflow employs snow water equivalent (SWE) measurements as predictors and streamflow observations as predictands. Gap filling of SWE datasets is accomplished using quantile mapping from neighboring SWE and precipitation stations, and Principal Component Analysis is used to identify independent predictor components. These components are then utilized in a regression model to generate ensemble hindcasts of streamflow volumes for 75 nival basins with limited regulation from 1979 to 2021, encompassing diverse geographies and climates. Using a hindcast evaluation approach that is user-oriented provides key insights for snow monitoring experts, forecasters, decision-makers, and workflow developers. The analysis presented here unveils a wide spectrum of predictability and offers a glimpse into potential future changes in predictability. Late-season snowpack emerges as a key factor for predicting spring/summer volumes, while high precipitation during the target period presents challenges to forecast skill and streamflow predictability. Notably, we can predict lower and higher than normal streamflows during the spring to early summer with up to five months lead time in some basins. Our workflow is available on GitHub as a collection of Jupyter Notebooks, facilitating broader applications in cold regions and contributing to the ongoing advancement of methodologies. [ABSTRACT FROM AUTHOR]

Geographic inequalities in water distribution can lead to relatively small regions driving or buffering changes in water availability in major watersheds. This research provides a baseline quantification of water distribution in Alberta, Canada, and evaluates changes in water yield, streamflow timing, and climate from 1976 to 2015. Annual water yields for 77 contributing watershed areas were calculated and assessed for trends, and 45 unregulated watersheds were evaluated for changes in key streamflow timing metrics. Mountain headwaters supply 22–38% of annual flow of major rivers, while plains watersheds provide relatively low annual yield. Annual yield and precipitation decreases dominated northern watersheds, with increases in southern watersheds, and mixed trends in central watersheds. Later spring freshet timing and earlier onset of the low flow season were detected for most watersheds, leading to more water over a shorter duration when paired with increasing yield, and water losses in late summer-autumn when paired with decreasing yield. Yield and flow timing metrics are strongly related to precipitation with temperature as a secondary driver, except freshet timing, which is driven by spring temperature. This study provides comprehensive information about geographic drivers of changing water distribution and quantifies the disparity between regions of water surplus and deficit. Les inégalités spatiales de la distribution de l'eau peuvent conduire à ce que des régions de taille relativement limitée puissent contrôler ou retarder la disponibilité de l'eau dans de bien plus grands bassins versants. Nos recherches ont permis d'établir l'état de l'art de la distribution de l'eau et sa quantification dans la province de l'Alberta, au Canada. Elles évaluent également les modifications des débits, de leur évolution temporelle et du climat de 1976 à 2015. Les exports en eau annuels de 77 bassins versants contributeurs ont été calculés, et l'occurrence de tendances temporelles y a été recherchée. Par ailleurs, les variations qui ont pu affecter les métriques de la distribution temporelle des débits liquides ont été évaluées dans 45 bassins versants dépourvus de barrages. La partie amont et montagneuse des bassins versants apporte 22 à 38 % du débit annuel des principales rivières, tandis que les zones de plaine de ces mêmes bassins génèrent une part relativement faible de ces mêmes apports. La baisse des exports d'eau annuels et des précipitations domine dans les bassins versants du nord de la province, tandis que des augmentations de ces mêmes variables ont été observées dans les bassins versants du sud et que des tendances mixtes ont été relevées dans les bassins versants du centre de la province. L'occurrence plus tardive des crues printanières dues à la fonte des neiges et le démarrage plus précoce de la période d'étiage ont été détectés dans la plupart des bassins versants, ce qui a conduit à ce que davantage d'eau soit transportée au cours d'une période plus courte lorsqu'une hausse globale a été observée. Au contraire, lorsqu'une baisse globale a été remarquée, une baisse des exports en eau a particulièrement été observée à la fin de l'été et à l'automne. Les métriques de la chronologie de l'évolution des apports en eau et des débits sont fortement liées aux précipitations tandis que les températures ne jouent qu'un rôle secondaire, sauf pour la période d'occurrence de la crue de printemps liée à la fonte des neiges, qui est fortement contrôlée par la température qui règne à cette période de l'année. Cette étude fournit des informations particulièrement exhaustives sur les facteurs de contrôle spatiaux de l'évolution de l'apport en eau et quantifie les disparités entre les régions marquées par un excédent d'eau et celles qui sont en déficit. [ABSTRACT FROM AUTHOR]

Hydrological systems across the globe are increasingly subjected to pressures from a warming climate and anthropogenic disturbance. Responses to stress can be nonlinear and variable; therefore, it is imperative to improve understanding of resilience and tipping points of these systems. Previous applications of resilience concepts to physical hydrology have been disconnected, and an increasing range of definitions and approaches has often led to improper applications. Here, upon synthesizing relevant literature, we define physical hydrological resilience as the ability of a watershed to maintain hydrological function while exposed to a stressor or perturbation, thus remaining within the same regime. From this definition a new framework for physical hydrological resilience is forwarded which includes four key traits that must be part of a robust application of resilience for physical hydrology. Any evaluation of resilience should (1) identify and justify a baseline regime; (2) evaluate hydrological function, one or more of collection, storage and release; (3); assess physical hydrological systems for both resistance and latitude and (4) evaluate important perturbations and processes and how they interact to manifest into resistance, latitude, and tipping points. The framework is applied to the example of the Elbow River in Alberta, Canada, using baseline (1979–2015) and future (2050–2080) conditions. Two key hydrological processes, snow accumulation and streamflow, are found to have low resistance to winter duration and late spring precipitation, respectively. The collection function is resilient to a warmer, wetter climate due to a large latitude in relation to air temperatures, while the release function is not resilient, shifting from a streamflow‐ towards an evapotranspiration‐dominated regime in the future. The successful application of the concepts of resilience to this complex catchment demonstrates how the framework could be applied across a diversity of catchments. Results of resilience studies can improve environmental monitoring and evaluation programs and complement social‐ecological resilience frameworks and water management strategies. [ABSTRACT FROM AUTHOR]