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Projecting Future Streamflow in Southeast Alaska

Streamflow Models in Southeast Alaska (Host Agreement Project)

Dates

Start Date
2017-10-01
End Date
2022-07-31
Release Date
2018

Summary

Understanding freshwater flow is frequently highlighted as a priority in land management planning and assessments. Changes in climate can impact streamflow through reduced snowpack and snowfall, earlier spring runoff, increased winter flow and flooding, and decreased summer flow. In Southeast Alaska, streamflow is expected to shift dramatically in response to changes in factors such as precipitation and air temperature. Understanding how streamflow might change is instrumental not only for predicting changes in plant distribution and soil moisture, but also for infrastructure planning. Culvert replacement, bridge design, hydropower development, water reservoir placement, and floodplain restoration planning all require information on [...]

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GulkanaRiver_AK_JeremyMatlock_BLM.jpg
“Gulkana River, Alaska - Credit: Jeremy Matlock, BLM”
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Purpose

Freshwater flow regimes in Southeast Alaska are expected to dramatically shift over time in response to climate drivers like precipitation and air temperature. Understanding the range of variation and future trends in stream discharge is essential for infrastructure planning. This may include culvert replacement, bridge design, hydropower development, drinking water reservoir location identification, and floodplain restoration. Projections of peak flow are particularly important for culvert and bridge engineering, while interannual variation and low flows may be more significant for hydropower and fish habitat restoration planning. Current empirical and process-based watershed discharge models predict current and past flows in ungaged catchments based on gaged basin data combined with spatially explicit watershed information and weather station data or weather reanalysis products. Typically, most long-term gages are placed on larger rivers, creating biases in predictions for smaller catchments; however, these biases can be corrected through iterative field verification and model refinement. In addition, the success of these predictions is tied to proper representations of future climate. Most general circulation model (GCM) output for future weather is too coarse (~ 1 degree) to capture the strong spatial variability found in Southeast Alaska. Current efforts by AK CSC Senior Scientists Bieniek and Bhatt to dynamically downscale GCM projections to high spatial resolution will provide the best available forcing data for process-based hydrologic modeling. We will work closely with agency partners to identify specific needs, to explore, modify, and test models, and to deliver useable watershed-scale information in a user-friendly system.

Project Extension

projectStatusIn Progress

Gulkana River, Alaska - Credit: Jeremy Matlock, BLM
Gulkana River, Alaska - Credit: Jeremy Matlock, BLM

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Communities

  • Alaska CASC
  • National and Regional Climate Adaptation Science Centers

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NCCWSC Science Themes
Water, Coasts and Ice
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CMS Themes
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DEPTH-2.7.5

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