Life at the Water’s Edge WHY is this important for reservoirs? John Hains 21 September 2006 Lake...
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Transcript of Life at the Water’s Edge WHY is this important for reservoirs? John Hains 21 September 2006 Lake...
Life at the Water’s Edge
WHY is this important for reservoirs?
John Hains21 September 2006
Lake Greenwood State Park
Lakes versus Reservoirs
I. Lakes and Reservoirs Have Different Characteristics, Origins
II. Processes Occurring in Lakes Also Occur in Reservoirs
III. There Are Additional Processes in Reservoirs
First: Solar energy drives the entire aquatic ecosystem. The lake’s characteristics are determined by the ways energy is processed, transferred, transformed, and expressed in temperature, weather, and water movement.
Second: The size, shape, geology, topography, vegetation, climate, land-use, and other human activity for the watershed affects the character of the lake.
Third: the internal fate of, and all the processes affecting water and materials in the reservoir, interacting with energy processes and depending on watershed processes - and thusly affecting patterns of stratification, sediment deposition, biological productivity, and water quality
Comparison of Natural Lakes to Reservoirs
Characteristic Natural Lakes Reservoirs
Distribution Mostly in glaciated regions Located mostly outside regionalso near rivers , their of glaciation. Mostly in southfloodplains and often associated region of U.S. Often in regions with karst regions or of water resource need.coastal plains.
Drainage area Smaller ratio of drainage area to Larger ratio of drainage area to lake surface area. to lake surface area.
Theoretical Longer, sometimes many years Shorter, often less than 1 year.retention time
Longevity Longer Shorter
Shoreline Simpler shape, shorter More complex, dendritic,greater SD number
Comparison of Natural Lakes to Reservoirs, cont’d
Outflows More stable, lake surface Releases according to fluctuations smaller demand schedules,
lake surface fluctuations greater
Inflows Often many smaller Often dominated by one or a order streams few major inflows (sometimes
other lake outflows).
Nutrient This depends on the watershed characteristics loading and the size of the watershed.
Water Greater Lesser, especially near clarity headwaters.
Note: these last general relationships are less dependable than previous generalizations.
Lake Name Shoreline length (km)Huron 5118
Superior 4796
Kentucky 3830
Michigan 2671
J. Strom Thurmond 1930
Barkley 1616
Hartwell 1548
Erie 1377
Kerr 1287
Ontario 1168
Champlain 945
Lanier 869
Norman 837
Greenwood 320
Tahoe 116
The Reservoir Perspective
Lake Surface Area
(sq. km)
Shoreline
(km)
Shoreline
Development
Watershed
Area (sq. km)
Watershed/
Surface Area
Huron 59600 6157 7.11 134100 2.25
Superior 82100 4796 4.72 128076 1.56
Kentucky 648 3830 42.44 105151 162.27
Michigan 57800 2671 3.13 117912 2.04
J. Strom Thurmond
283 1930 32.36 15961 56.40
Barkley 378 1616 23.45 45579 120.58
Hartwell 227 1548 28.98 5405 23.81
Erie 25700 1377 2.42 78128 3.04
Greenwood 46 320 13.31 1891 41.12
Tahoe 495 114 1.45 812 1.60
Mendota 40 35.2 1.57 602 15.11
Lake Surface Area
(sq. km)
Shoreline
(km)
Shoreline
Development
Watershed
Area (sq. km)
Watershed/
Surface Area
Greenwood 46 320 13.31 1891 41.12
Tahoe 495 114 1.45 812 1.60
Mendota 40 35.2 1.57 602 15.11
Lake Surface Area
(sq. km)
Shoreline
(km)
Shoreline
Development
Watershed
Area (sq. km)
Watershed/
Surface Area
Greenwood 46 320 13.31 1891 41.12
Tahoe 495 114 1.45 812 1.60
Mendota 40 35.2 1.57 602 15.11
In Conclusion:
The fourth factor - shoreline complexity, length, and development – is a factor that can be important for reservoir ecosystems and water quality. And it is the only factor for which individual property owners have direct influence and control.
In Conclusion:
The fourth factor - shoreline complexity, length, and development – is a factor that can be important for reservoir ecosystems and water quality. And it is the only factor for which individual property owners have direct influence and control.
So the better question for lakeshore management is not “Why?”
But rather “Why Not?”