Progress 05/01/05 to 04/30/11
Outputs
OUTPUTS: Data, models, and analysis from this project have been shared with resource management agencies, professional society members, the public, and user groups, through reports, presentations, data products, and through continuing education venues. In addition, various aspects of this project have supported five undergraduate senior theses and enriched undergraduate education through field trips and increased local relevance. Agencies that have benefited include the AK Dept. of Natural Resources, the U.S. Natural Resources Conservation Service, the Salcha-Delta Soil & Water Conservation District, the AK Dept. of Fish & Game, and the U.S. Army Corps of Engineers. Professional societies include the American Water Resources Association (local, state, and national levels), the Society of American Foresters (local and state levels), and the American Fisheries Association (state level). Presentations have been made to the Harding Lake Watershed Association, the Harding Lake Property Owners Association, and the OSHER Life Long Learning program. Eight years of lake level and rainfall data for Harding Lake, and five years of 15-minute interval pan evaporation data were among the local data products shared. Among the outputs/products made available through this project are: new methods of estimating net radiation and subsequent ways to implement Penman type formulas; a spreadsheet lake water balance model; a broad scale method of relating monthly global radiation input to sky cover conditions; a time series analysis of 74 years of pan evaporation records and a time series analysis of 100 years of growing season length for Fairbanks, AK. PARTICIPANTS: Individuals: PI/ John D. Fox, PhD Collaborators/contacts: AK DNR, AK DF&G, US NRCS, Salch-Delta Soil & Water Conservation District, U.S. Corp of Engineers. Training/Professional Development: 5 undergraduate senior theses. General undergraduate education via field trips to site and enhanced information. TARGET AUDIENCES: Data, models, and analysis from this project have been shared with resource management agencies, professional society members, the public, and user groups, through reports, presentations, data products, and through continuing education venues. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Review of evapotranspiration techniques underscored the sensitivity of methods to net radiation and climatic data availability. Two significant results of this project for high latitude regions are (1) the identification and correction of a deficiency in the commonly used Lui & Jordan method of estimating clear sky global radiation, and (2) the significant improvement in the statistical relationship between monthly global radiation received on the ground, and monthly sky cover. This new relationship allows for the direct influence of latitude by including optical air mass. This result, along with analysis of pan evaporation data, points to the utility of the PENPAN method of estimating evaporation in northern regions. Monitoring both pan evaporation and lake level revealed lake evaporation can occur long after evaporation pans have become frozen and inoperable. This shifts control of actual evaporation away from solar and net radiation, to factors related to heat storage. Studies carried out at Harding Lake have resulted in an understanding of this lake's history, water balance and sensitivity to natural and human caused events. Reviewing historical evidence, modeling, and field data indicate that recent changes in lake level have not been due to climate change. On a broader scale of landscape water balance, another product of this project has been an enhanced spreadsheet version of the standard geography method called "the local water balance". This tool allowed an advisory review of the efficacy of using precipitation (P) minus potential evapotranspiration (PET), as an index of climate change in the arctic and sub-arctic, to Scenarios for Alaska Planning. Other related impacts of this project have been the measurement of stomatal conductances for aspen and poplar trees growing on an experimental landfill site, and reviews of trends in growing season length and pan evaporation in Fairbanks, AK. Conductance data reinforce the observations that a living, arboreal landfill cap are more effective at preventing deep percolation of infiltrated water than a traditional "clay" cap. Growing season length in Fairbanks, AK, had been reported to increase 50% from 1906 to the present. Re-analysis of those data revealed a systematic difference between current and past weather station locations used to construct the time series. If allowance is made for this difference in station data, the increase in growing season was at most 36% and at least 28%. An analysis of the historical record of Fairbanks' pan evaporation measurements found a slight increasing trend in the average daily pan evaporation rate from 1931 to 2005. This is in contrast to many worldwide studies that have found a decreasing trend in recent decades. This project has increased our understanding of the spatial and temporal variations of evaporation in the water balance of boreal forest lakes and landscapes. This has been accomplished by new calculations of the basic input regimes of solar radiation; by investigation of historical climate data; by the modeling of the local water balance; and by the measurement of water vapor loss from whole lakes to individual plant leaves.
Publications
- No publications reported this period
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Progress 01/01/10 to 12/31/10
Outputs
OUTPUTS: Data, models, and analysis continue to be the outputs of this project. Lake level data, pan evaporation data, and stomatal conductance data were collected for the 2010 summer period. The data and analysis were shared with the State of Alaska Dept. of Natural Resources, the U.S. Natural Resources Conservation Service (NRCS), the Salch-Delta Soil & Water Conservation District, and the Alaska Dept. of Fish & Game (ADF&G). A presentation on this aspect of the project was made this year through the OSHER Life Long Learning program. The presentation summarized Harding lake level history, current status of management intervention, and future lake level possibilities under different weather and management scenarios. In addition to the lake water balance model, another output of this project has been an enhanced spreadsheet version of the standard geography method called "the local water balance". This tool and other information allowed an advisory review of the efficacy of using P-PET (precipitation minus potential evapotranspiration) as an index of climate change in the arctic and sub-arctic to the SNAP program (Scenarios for Alaska Planning). This year, one undergraduate senior thesis project was supported. PARTICIPANTS: In addition to the principle investigator, an undergraduate student in Natural Resources Management from the University of Alaska Fairbanks, Brianna Graves, participated in the measurement of stomatal conductances. Other collaborators included Jim Vohden, hydrologist for the Alaska Dept. of Natural Resources; Jeff Durham, Salcha Soil & Water Conservation District; Audra Brase, ADFR&G; Mike Doxey, ADF&G retired; and Barbara Schulmann, Harding Lake land owners association; Dr. William Schnabel and Bill Lee, UAF Water & Environmental Research Center; and cooperation from Elmondorf Air Force base, Anchorage, AK. TARGET AUDIENCES: The target audiences for information in this project include the State of Alaska Dept. of Natural Resources, the Alaska Dept. of Fish & Game, the U.S. Natural Resources Conservation Service, the Salcha-Delta Soil & Water Conservation District, the Harding Lake Watershed Assoc., the Harding Lake land owners association, and the Fairbanks North Star Borough. The general public is an additional audience. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Previously collected data support the hypothesis that the observed decline in lake level during winter is simply the progressive freezing and grounding of the ice from the shore out into progressively deeper waters until it reaches a point where maximum ice thickness is less than the depth of the water and ice is no longer grounded. Therefore, the winter drop in lake level may not represent a true loss of water from the lake. If this is the case, and net groundwater output is zero, the major impact would be that lake evaporation in the summer is higher than previously thought. This was the fourth summer of pan evaporation measurements. Two significant findings have been that evaporation from a standard pan continues throughout the night and that lake evaporation continues well beyond the date when evaporation pans freeze. Evaporation during the autumn period is disassociated with formulas driven by current solar radiation since the energy source is heat stored in the lake water itself. Vapor pressure gradients are strong due to low air temperatures. This is the seventh year of monitoring lake levels and the fourth year of data after the divergent feeder stream was re-directed to the lake. This year's results reinforce the notion that the fraction of flow from the feeder stream going to the lake should be increased as much as possible if the input is going to do more than just cancel out evaporative losses. This is particularly true during low precipitation years. The overall data collection, modeling, and historical observations now support the hypothesis that the stream feeding Harding Lake was originally diverted (captured) following the regional flood events in 1967. Previous hypotheses involving the 1937 earthquake, beaver damming, and human manipulation have been rejected. Other related outcomes of this project have been the measurement of stomatal conductances for aspen and poplar trees growing on an experimental landfill site, and a critical review of historic trends of growing season lengths in Fairbanks. Conductance data, while limited by a particularly wet summer in South Central Alaska, reinforce the observations that a living, arboreal landfill cap may be more effective at preventing deep percolation of infiltrated water than a traditional "clay" cap. Growing season length in Fairbanks, Alaska, had been reported to increase nearly 50% from 1906 to the present. Re-analysis of those data revealed a systematic difference between current and past locations of the weather stations used to construct the time series. If allowance is made for the systematic differences in station data, the increase in "growing" season was at most 36% and at least 28%. This project has increased our understanding of the spatial and temporal variations of evaporation in the water balance of boreal forest lakes and landscapes. This has been accomplished by new calculations of the basic input regimes of solar radiation; by investigation of historical climate data; by the modeling of the local water balance; and by the measurement of water vapor loss from whole lakes to individual plant leaves.
Publications
- No publications reported this period
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Progress 01/01/09 to 12/31/09
Outputs
OUTPUTS: Data, models, and analysis continue to be the outputs of this project. Lake level data and pan evaporation data were collected for the 2009 summer period. Winter lake level measurements were obtained for 2008-2009. The data and analysis continue to be shared with the State of Alaska Dept. of Natural Resources, the U.S. Natural Resources Conservation Service (NRCS), the Salcha-Delta Soil & Water Conservation District, and the Alaska Dept. of Fish & Game (ADF&G). A poster presentation on this aspect of the project was delivered at the American Water Resources Association Spring Specialty Conference, held in Anchorage, AK in May 2009. The poster summarized Harding lake level history, current status of management intervention, and future lake level possibilities under different weather and management scenarios. This information was used by ADF&G cooperator, Audra Brase, in a presentation to the American Fisheries Association. Alaska Dept. of Fish & Game will manage the lake level for pike habitat. An analysis of the historical record of Fairbanks pan evaporation measurements found a slight increasing trend in the average daily pan evaporation rate from 1931 to 2005. This study supported one undergraduate Senior Thesis research project. In addition to the lake water balance model, another output of this project is an enhanced spreadsheet version of the standard geography method called "the local water balance". PARTICIPANTS: In addition to the principle investigator, an undergraduate student in Natural Resources Management from the University of Alaska Fairbanks, Ronald Norman, participated in the analysis of the historic record of pan evaporation recorded at the Fairbanks Agricultural and Forestry Experimental Station. Other collaborators included Jim Vohden, hydrologist for the Alaska Dept. of Natural Resources; Jeff Oatley, hydrologist and engineer, NRCS; Jeff Durham, Salcha Soil & Water Conservation District; Audra Brase, ADF&G; Mike Doxey, ADF&G retired; and Barbara Schulmann, Harding Lake land owners association. TARGET AUDIENCES: The target audiences for information in this project include the State of Alaska Dept. of Natural Resources, the Alaska Dept. of Fish & Game, the U.S. Natural Resource Conservation Service, the Salcha-Delta Soil & Water Conservation District, the Harding Lake Watershed Association, and the Harding Lake land owners association, and the Fairbanks North Star Borough. The general public is an additional audience and I made a presentation of my results this year to a class for the Osher Life Long Learning program. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Three years of winter lake level measurements was obtained in an attempt to isolate a net groundwater flow component from the overall rate of loss (evaporation loss + net groundwater loss). Although the lake level initially declined under the seasonal ice cover, this decline again slowed or stopped during the later winter period. Since change in winter lake levels is the net effect of ground water input and ground water output, the observed pattern must be explained by either a reduced output or an increased input as winter progresses. The later case doesn't seem logical. However, the overall pattern of less net winter decline in the most recent year seems consistent with wetter antecedent summer and perhaps greater total groundwater input over the winter. An alternative hypothesis has been put forth that the observed decline in lake level during winter is simply the progressive freezing and grounding of the ice from the shore out into progressively deeper waters until it reaches a point where maximum ice thickness is less than the depth of the water and ice is no longer grounded. The volume of water bound up in grounded seasonal ice is effectively "removed" from that part of the lake where ice is assumed to be "floating" and may explain measured decline in the water surface elevation during early winter, the cessation of decline during mid-winter, and approximate return in the spring to pre-freezing water level. If this is the case and net groundwater output is zero, the major impact would be that lake evaporation in the summer is higher than previously thought. This was the third summer of pan evaporation measurements. Two significant findings have been that evaporation from a standard pan continues throughout the night and that lake evaporation continues well beyond the date when evaporation pans freeze. During the autumn period evaporation is disassociated with formulas driven by current solar radiation since the energy source is heat stored in the lake water itself. Vapor pressure gradients are strong due to low air temperatures. A rapid and substantial increase in lake level was documented in 2008 as near record rainfall occurred in late July and early August. The lake surface for 2009 held fairly steady at the level ratcheted up by last year's rain. This is the sixth year of monitoring lake levels and represents the third year of data after the divergent feeder stream was re-directed to the lake. This years results indicate that the fraction of flow from the feeder stream going to the lake should be increased if the input is going to do more than just cancel out evaporative losses. This project has increased our understanding of the spatial and temporal variations of evaporation in the water balance of boreal forest lakes and landscapes.
Publications
- 2009. Fox, J.D. Water level changes in a subarctic lake near Fairbanks, Alaska. Extended abstract and poster: Proceedings of AWRA 2009 Spring Specialty Conf., May 4-6, Anchorage, AK.
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Progress 01/01/08 to 12/31/08
Outputs
OUTPUTS: The outputs of this project continue to include: data, models, and analysis. Lake level data and pan evaporation data were collected for the 2008 summer period. In addition, another set of winter lake level measurements were obtained. The data and preliminary analysis continue to be shared with the State of Alaska Dept. of Natural Resources, the U.S. Natural Resources Conservation Service (NRCS), the Salcha-Delta Soil & Water Conservation District, and the Alaska Dept. of Fish & Game. In May of 2008 I set up a continuous, self-running powerpoint show to be shown at the Harding Lake landowner's association annual meeting. On December 2, 2008 I met with representatives of the aforementioned agencies and the Harding Lake Association to discuss the status and outlook on lake level recovery. A poster presentation on this aspect of the project has been accepted for the American Water Resources Association Spring Specialty Conference, to be held in Anchorage, AK in May 2009. A model of Harding Lake was used to estimate undocumented contributions of Rogge Creek to the lake in the 1980's. The model was tested against the 5-year lake level measurement data, including periods with and without contributions from Rogge Creek. These results will be useful to Alaska Dept. of Fish & Game who will manage the lake level for pike habitat. One undergraduate Senior Thesis research project was completed this past year. PARTICIPANTS: In addition to the principle investigator, an undergraduate student in Natural Resources Management from the University of Alaska Fairbanks, Josh Kuntz, participated in collection of winter field data which was the basis for his senior thesis. Other collaborators include Jim Vohden, hydrologist for the Alaska Dept. of Natural Resources;Jeff Oatley, hydrologist, NRCS; Jeff Durham, Salcha Soil & Water Conservation District; Audra Brase, AK Dept. of Fish & Game; Mike Doxey, ADF&G retired; Barbara Schulmann, Harding Lake land owners association. TARGET AUDIENCES: The target audiences for information gathered in this project include the the State of Alaska Dept. of Natural Resources, the U.S. Natural Resources Conservation Service (NRCS), the Salcha-Delta Soil & Water Conservation District, the Alaska Dept. of Fish & Game, the Harding Lake Watershed Association, and the Harding Lake landowners association. I provided an automated powerpoint show about the history of lake level fluctuations in Harding lake and about the findings of this study. I also met with agency representatives in December to review data and findings of the 2008 field season. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
An additional set of winter lake level measurements was obtained during the winter of 2007-2008 in an attempt to isolate a net groundwater flow component from the overall rate of loss (evaporation loss + net groundwater loss). Although the lake level initially declined under the seasonal ice cover, this decline again slowed or stopped during the later winter period. Since change in winter lake levels is the net effect of ground water input and ground water output, the observed pattern must be explained by either a reduced outflow or an increased inflow as winter progresses. The later case doesn't seem logical. However, the overall pattern of less net winter decline in the most recent year seems consistent with wetter antecedent summer and perhaps greater total groundwater input over the winter. Winter lake level measurements were the basis for a student's senior thesis project that was completed in 2008. This was the second summer of pan evaporation measurements. Considerably less evaporation occurred this year due to a high number of rainy days. Lake evaporation seems to continue well beyond the date when evaporation pans freeze and appears to be disassociated with formulas driven by current solar radiation since the energy source is heat stored in the lake water itself. Vapor pressure gradients are strong due to low air temperatures. We are continuing efforts to adapt the Penpan methodology to Alaska as a way of estimating more reasonable pan coefficients for lake evaporation. A new undergraduate, senior thesis student will be analyzing historic pan evaporation data for Fairbanks. A rapid and substantial increase in lake level was documented this past summer as near record rainfall occurred in late July and early August. This is the fifth year of monitoring lake levels and represents the second year of data after the divergent feeder stream was re-directed to the lake. In spite of continued operational problems with the control structure, simulation studies indicate a significant contribution to the lake. This project has increased our understanding of evaporation in the water balance of boreal forest lakes and landscapes.
Publications
- No publications reported this period
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Progress 01/01/07 to 12/31/07
Outputs
OUTPUTS: The outputs of this project to date include: data, models, and analysis. The data collected and the preliminary analysis continue to be shared with the State of Alaska Dept. of Natural Resources, the U.S. Natural Resources Conservation Service (NRCS), and the Salcha-Delta Soil & Water Conservation District. On December 15, 2007 I made an oral presentation to the Alaska Section of the American Water Resources Association, summarizing information gathered on the historic lake levels at Harding Lake, and on model projections. A CD of the slides from this presentation is available to interested parties, as is a document summarizing model results and analysis of future lake levels. A copy of the model has been given to the local NRCS. Modeling results will also be useful to Alaska Dept. of Fish & Game who will manage the lake level for pike habitat. This study is currently supporting one undergraduate Senior Thesis research project.
PARTICIPANTS: Individuals who worked on this project include myself, John D. Fox, and an undergraduate student, Mr. Josh Kunz. I collaborated with Mr. Jim Vohden, hydrologist with the AK Dept. of Natural Resources, and Mr. Jeff Oatley, project manager/hydrologist with the regional office of the Natural Resource Conservation Service. In addition, I have been in contact with several residents of the Harding Lake area. I have also interacted with Mr. Mike Doxey, retired from AK Dept. of Fish & Game.
TARGET AUDIENCES: The target audiences are local, state, and federal water resource managers and the scientific community interested in hydrology. I gave a presentation on the results of my research to the Alaska Section of the American Water Resources Association, which included many local, state and federal employees concerned with water management and was open to the public. I have also provided data and analysis of how long it will take Harding Lake to reach target levels under assumed future hydrometeorological conditions in my correspondence with individual residents of Harding Lake. I have contributed information and data to a file maintained at the University of Alaska Fairbank, International Arctic Research Center library.
Impacts
An additional set of winter lake level measurements was obtained during the winter of 2006-2007 in an attempt to isolate a net groundwater flow component from the overall rate of loss (evaporation loss + net groundwater loss). Although the lake level initially declined under the seasonal ice cover, this decline slowed or stopped during the later winter period. This is in direct contrast to the previous winter readings. We are trying to reconcile the contrasting data and review the validity of our measurements. This study will be the basis for a student's senior thesis project. A spreadsheet version of a monthly lake water balance model was run using precipitation, pan evaporation, and runoff data from nearby weather and runoff stations for the time period 1950 - 2007. The simulation was calibrated with 2 measured lake levels, one in 1978 and one in 2006, assuming the diversion of the major feeder stream occurred in 1968. The ground water coefficient was the main
calibration parameter. The value of the latter which worked best translates into a hydraulic conductivity of 58.5 meters/day which is within the range of "textbook" values for the sand and gravel composition of the terrace deposits to the North of the lake. Model testing was carried out with measured lake levels not used in the calibration process. The model underestimated lake levels in 1985 but performed well for the summer months of 2004-2007. Uncertainty remains for winter conditions. This model gives managers an idea of the magnitude of past lake level fluctuations and an indication of what to expect in the future under various assumptions of weather and management actions. This past summer a recording pan evaporation station was operated in an open site on the north shore of the lake. Data will be compared to the observed rate of lake decline during non-rain periods, which averages approximately 3mm/day. This is the fourth year of monitoring lake levels and represents the first
year of data after the divergent feeder stream was re-directed to the lake. Operational problems, including channel icing, caused much of the runoff to by-pass the control structure and result in a small but unknown contribution to the lake. The lake level data do verify that, in contrast to the previous 3 summers, the lake did not decline this summer. On the more general level, I have found a good statistical relationship between mean monthly Kt (ratio of measured global radiation to extra-terrestrial radiation on a horizontal surface) and mean monthly sky cover, by including an index of optical air mass for each month. This relationship holds well for a wide variety of locations in the United States and should help expand estimates of global radiation and therefore evapotranspiration to areas without primary radiation data. This is particularly significant in Alaska with its sparse data network.
Publications
- No publications reported this period
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Progress 01/01/06 to 12/31/06
Outputs
Data collected on lake level under the ice indicated a pronounced decline throughout the winter. The net rate of groundwater outflow appeared to increase sharply in late winter. This may have been due to a reduction in groundwater inflow as the watershed soils froze progressively deeper through the winter. Additional winter season measurements will be needed to determine whether this is a repeatable pattern or just the response to that particular year's conditions. Another summer (2006) of 15-minute lake level data was collected which documents continued lake level decline. Equipment was obtained at the end of the summer that will enable 15-minute recording of pan evaporation. A site for a pan evaporation station was selected and a protective enclosure erected in the fall. Equipment was temporarily installed and tested which led to the interesting observation that evaporation was occurring 24 hours a day. A full season of detailed pan data is expected for the summer
of 2007. I am exploring the technique of Linacre (1994) to estimate pan and lake evaporation and possibly derive pan coefficients for Alaska.
Impacts
The data collected to date and the preliminary analysis have been shared with the State of Alaska Dept. of Natural Resources, the U.S. Natural Resources Conservation Service, and the Salcha-Delta Soil & Water Conservation District for the planning and implementation of a lake level restoration project for Harding Lake. Rogge Creek, historically the major feeder stream to Harding Lake, is scheduled to be re-diverted into the lake by this coming spring. This should afford an opportunity to test predictions of the lake model and provide a new water balance regimen to test our understanding of the lake's hydrology. Modeling results should also be useful to Alaska Dept. of Fish & Game who will manage the lake level for pike habitat after the diversion takes place. In a more general context, the expected results of this project should help managers estimate lake and landscape evapotranspiration. This capability will be useful immediately to consultants and managers working
in Alaska, but also help researchers on Arctic climate change to sort out how evaporation rates might change in response to atmospheric temperature and moisture scenarios. The recent scientific literature has documented that, contrary to most expectations, pan evaporation in many regions of the world has declined as temperatures have increased. We hope to look at the historical pan data for Alaska and compare it to historical temperature data to see if similar a relationship is evident in Alaska. This study is currently supporting one undergraduate Senior Thesis research project.
Publications
- No publications reported this period
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Progress 01/01/05 to 12/31/05
Outputs
In the first six months of this new project to investigate the suitability of methods for estimating evapotranspiration from boreal forest landscapes I have assembled and reviewed considerable literature, begun an analysis of historic data on pan evaporation from Fairbanks, Alaska, collected 15-minute lake level data for the 2005 ice-free period on Harding Lake, assembled 50 years of historic hydrometeorological data as representative input to a lake water-balance model, and performed a preliminary monthly water-balance analysis of Harding Lake (interior Alaska) for the past 50 years. At this time evaporative loss during the ice free season explains most but not all of the current lake level decline. Net groundwater seepage loss must be occurring in order to explain historic patterns. Model calibration indicates the magnitude of net groundwater loss to be in the order of 30 mm/month. Initial field measurements of lake level decline under ice-cover, and therefore
without evaporative loss, support this model estimate. Further measurements are scheduled through the winter of 2005-2006 to confirm. Detailed analysis of summer lake level data remains to be done and should allow a more accurate estimate of lake evaporation.
Impacts
Harding Lake is a major highway-accessible recreational setting in interior Alaska. The level of water in this lake declined dramatically in the 1970s and again from the early 1990s until the present. A federal habitat restoration project was recently approved which involves a water diversion scheme scheduled to be implemented this Spring (2006). The data collected to date and the preliminary analysis have been shared with the State of Alaska Dept. of Natural Resources, the U.S. Natural Resources Conservation Service, and the Salcha-Delta Soil & Water Conservation District, in order to enhance the managers understanding of Harding Lakes hydrology, improve on the diversion structure design, and help provide estimates of how long it will take for the lake level to rise to the target elevation. Modeling results should also be useful to Alaska Dept. of Fish & Game who will manage the lake level for pike habitat after the diversion of water to the lake takes place. The
context and data for this project supported the following undergraduate research projects: Hall, Cassidee. 2005. Assessment of Harding Lake level changes through hydrologic modeling. A Senior Thesis presented in partial fulfillment of the B.S. degree in Natural Resources Management. December, 2005. Ranft, Richard. 2005. Does Harding Lake have a surface outflow? A Senior Thesis presented in partial fulfillment of the B.S. degree in Natural Resources Management. December, 2005.
Publications
- No publications reported this period
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