Identification of Seasonal Streamflow Regimes and Streamflow Drivers for Daily and Peak Flows in Alaska

Abstract

Alaska is among northern high‐latitude regions where accelerated climate change is expected to impact streamflow properties, including seasonality and primary flow drivers. Evaluating changes to streamflow, including flood characteristics, across this large and diverse environment can be improved by identifying the distribution and influence of flow drivers. Using metrics of mean monthly streamflow data from 253 streamgages, seasonal flow regimes were clustered to guide identification of seasonal flow drivers and form hydrologic groups for identification of peak‐flow populations. Nine seasonally distinct subclasses described variability within three classes dominated by (mostly fall) rainfall, (spring) snowmelt, and (summer) high‐elevation melt. The most glacierized basins exclusively grouped into high‐elevation melt subclasses, and less glacierized basins sometimes exhibited seasonal patterns aligned with rainfall‐dominated and snowmelt‐dominated regimes. Peak‐flow populations varied by subclass from dominant rainfall or dominant snowmelt to mixed rainfall–snowmelt or mixed rainfall, snowmelt, and high‐elevation melt. Within subclasses, rainfall generated higher mean peak flows (relative to mean annual flow) than snowmelt or high‐elevation melt. Seasonal flow regimes showed clear but complex associations with basin characteristics, primarily elevation and winter temperature, and with geographic location. These dependencies provided elevation‐based analogies for changes associated with warming and insights for seasonal flow regime prediction and hydrologic region delineation. These results provide a spatially comprehensive perspective on seasonal streamflow drivers across Alaska from historical data and serve as an important historical basis for analysis.

Seasonality of Solute Flux and Water Source Chemistry in a Coastal Glacierized Watershed Undergoing Rapid Change: Wolverine Glacier Watershed, Alaska

“…We defined four hydroclimatic periods that represent time‐varying hydrologic process common to most glacierized catchments and therefore can be widely transferrable (e.g., Curran & Biles, 2021; Fountain & Tangborn, 1985, see Sections 2.3 and 4.2). Here the divisions between periods were manually determined, leveraging the stark differences between periods; however, a machine learning‐based approach can be developed and is the subject of ongoing work.…”

“…Hydrograph classification has been used extensively to determine characteristic responses to hydroclimatic forcing and to better determine the mechanisms behind complex hydrologic process and flow paths (Olden et al., 2012). Specifically, it has been applied to glacierized watersheds using a range of methods, at various spatial and temporal scales (Curran & Biles, 2021; Hannah et al., 2000; Sergeant et al., 2020; Swift et al., 2005). Similarly, concentration discharge relationships have been used to determine watershed hydrologic function and water sources (Evans & Davies, 1998; Godsey et al., 2009; Maher, 2011; McGlynn & McDonnell, 2003).…”

Concentration‐Discharge Patterns Across the Gulf of Alaska Reveal Geomorphological and Glacierization Controls on Stream Water Solute Generation and Export

“…To explore concentration‐discharge relationships we chose stream sites that have at least 12 paired concentration and discharge measurements for $${\text{HCO}}_{3}^{-}$$, Ca 2+ , Mg 2+ , Na * (Cl‐corrected; Ibarra et al., 2016; Moon et al., 2014), K + , $${\text{SO}}_{4}^{2-}$$, SiO 2 , and TSS resulting in 34 stream sites total that fit our criteria. For watershed boundaries of the 34 stream sites with requisite C ‐ Q data, we use the watersheds delineated by Curran and Biles (2021).…”

Stuck in the Wild—The Hydrology of the Teklanika River (Alaska) in the Summer of 1992

“…Relevant and recent discussion of the hydrology of Alaska rivers is provided by Curran and Biles (2021). They categorize rivers into three broad classes, based upon the timing of peak flow and also the main drivers of flow.…”

“…Finally, highelevation melt watersheds (category 3) see a broad peak that spans summer months and is due to high-elevation snow melt and also ice-melt from glacier surfaces. Curran and Biles (2021) go on to subdivide (A, B, C, etc.) these classes based upon finer-scale details of the timing and magnitudes of hydrographs within each category.…”