State Water Resources Research Institute Program


Project ID: 2012AK106B
Title: Response of Water Supply Lakes to Climate Change in Western Alaska: a Case Study of Past, Present, and Future Thermal Regimes in Kotzebue
Project Type: Research
Start Date: 3/01/2012
End Date: 2/28/2013
Congressional District: Alaska
Focus Categories: Water Quality, Climatological Processes, Water Quantity
Keywords: Arctic, lakes, water supply, thermal regime, climate change
Principal Investigator: Arp, Christopher Douglas (University of Alaska)
Federal Funds: $ 17,489
Non-Federal Matching Funds: $ 5,004
Abstract: Lakes are abundant landforms and ecosystems that dominate large portions of Arctic coastal plains in Alaska and store large amounts of surface water, affect permafrost conditions, export carbon, and provide habitat for fish and wildlife. Arctic lakes are increasingly sensitive to climate change through shifts in water balance, basin expansion and catastrophic drainage, and altered water quality because of warming temperatures. Coastal lakes are also vulnerable to storm surge flooding and tapping by coastal erosion. Near many towns and villages, Arctic coastal lakes also provide valuable and stable supply of water for drinking, washing, and other municipal uses. The thermal regimes of lakes are a fundamental attribute of lake ecosystems and also directly affect water quality for municipal water supply through regulating algal blooms and sediment water-column chemistry, which may be sensitive to progressive climate warming and anomalous warm summer warm weather. Additionally, a lack of understanding the thermal response of water supply lakes relative to natural water balance warrants investigations. Thus, the goal of this study is to understand the thermal regimes (surface and bed temperature, and stratification) of water supply lakes relative to natural lakes without water extraction and how they respond to weather patterns and local climate at a variety of time scales. To accomplish this goal we began investigations of two lakes being used for water supply by the City of Kotzebue and two adjacent reference lakes on the Baldwin Peninsula during the summer of 2011. At each lake, we monitored surface and bed temperatures, water levels, and conductivity, along with weather parameters that partially overlap with climate data collected long-term (since 1901) at the Kotzebue airport. Data collected during this period will be used to develop models to simulate lake temperature regimes using an empirical approach based on air temperature and solar radiation and 2-dimensional physical model (MyLake, Multi-year Lake Simulation Model). We intend to use these models to hindcast summer lake thermal regimes from 2001-2010 with validation from MODIS satellite surface temperature measurements form Kotzebue Lagoon (monitored with sensors in 2011). Simulation of this 10 year period will provide a reasonable baseline of thermal regimes of the water supply and reference lakes and their interannual variability. A long-term hindcast simulation will then be conducted for the full period of climate data (1950 - 2011) without observational validation data to assess trends in lake thermal regimes. Forecasts of lake thermal regimes to 2060 will be driven by downscaled global climate model (GCM) output (A1B scenario from composite of five models in ERA-40 set) using both model types (empirical regression and MyLake). These results from this study will help understand current seasonal variation in lakes used for water supply compared to natural Arctic lakes, provide a baseline to evaluate interannual variation in thermal regimes, and provide evidence of how Arctic coastal lakes have changed during the past half century and projections of how they may change during the next half century.

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