Filters: partyWithName: Joseph H Wlosinski (X) > partyWithName: James T Rogala (X)
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The effects of changing levee and water level management practices on present habitat types and amounts on the Upper Mississippi River floodplain at Pool 25 were predicted. The intent of the study was to investigate a broad range of plans that would provide coarse resolution information and the tools needed to study specific plans in the future. Two conditions were investigated for levees: the present levee system and all levees removed. Five water level management plans were studied: the present plan, two plans that would increase water levels, and two plans that would decrease water levels. The levee and water level management variables resulted in a total of ten unique management alternatives. Each was studied...
The likelihood of 1- or 2-foot drawdowns, and the area affected by such alternative drawdowns, was estimated for Pool 13 on the Upper Mississippi River. Minimum water surface (elevation) requirements were compared to computed water surface profiles to determine a critical low flow that would allow a navigation channel 400 feet wide and 10.5 feet deep. An upper limit on flow was established based on the flow at which open river conditions would exist for a given drawdown. The range in flows that would allow for a drawdown was used to estimate success rates using historical daily discharge data. Success rates were determined for a variety of drawdown durations between two time periods, May 1 August 15 and June 15...
An experiment to improve ecological conditions while maintaining a 9-foot (2.74-m) navigation channel was continued in 1995 and 1996 on the three pools of the Upper Mississippi River managed by the St. Louis District, U.S. Army Corps of Engineers. Water levels were held from 1 to 3 feet (0.3 to 0.9 m) lower than maximum regulated elevations at the dam from about mid-June through July in Pools 24 and 25 and Melvin Price Pool. Water levels were then gradually raised as discharge allowed. Vegetation was surveyed along an elevational gradient in eight areas in 1995 and six areas in 1996. Seven plant genera were identified in 1995 and five genera in 1996. Amaranthus spp. (pigweed), Cyperus spp. (chufa), Echinochloa spp....
We estimated the amount of land that would have to be acquired if an alternative water-level management plan was used for Pool 25 on the Upper Mississippi River. The work was performed as part of a study to evaluate water regulation alternatives that could minimize negative impacts and increase ecological benefits of dam operation. We used a one-dimensional model (HEC-2) to estimate the ordinary high-water profile and water surfaces at various discharges and management options, by river mile. Maps of these data were then created with a geographic information system, along with maps of land elevations, both above and below the surface of the river, lands controlled by the managing agency, and levees. The ownership...
The floodplain of the Upper Mississippi River has been significantly modified by man since 1824. Changes include the removal snags and sandbars, elimination of rapids, closing of side channels, construction of wing dams, 29 navigation locks and dams, and hundreds of miles of levees. Watershed changes have transformed much of the landscape from forest/grassland habitats to agriculture. We studied floodplain changes by analyzing historical water elevation and discharge data collected since 1861 and spatial data since 1891. Open water and marsh habitats have generally increased in the dammed portion of the river. A 28% reduction in open water and a 38% reduction in woody and terrestrial habitats have occurred In areas...
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