No abstract

Caloosahatchee River watershed and estuary has experienced a general decline in the water quality over the last several decades due to agriculture practices, development, and other human activities. The objective of this study is to assess the water quality condition in coastal Caloosahatchee River watershed by analyzing the data collected by South Florida Water Management District and Lee County. Results indicated that during 1995 to 2006, averaged annually, Lake Okeechobee released 1124 million m3 of freshwater into the Caloosahatchee River, whereas the average annual freshwater discharge out of the Caloosahatchee River was approximately 2277 million m3. Lake Okeechobee might have more impacts on the water quality condition of Caloosahatchee River in dry season than wet season. The loads ratios of Lake Okeechobee to those out of Caloosahatchee River were much higher in dry season than wet season for flow (72% to 36%), total phosphorus (63% to 20%), total nitrogen (72% to 41%), organic nitrogen (85% to 47%), and NH3 (78% to 39%). In the coastal watershed area where the urban area is concentrated, of the total 5453 water samples, 74% of them have dissolved oxygen concentration less than 5 mg L(-1), the United States Environmental Protection Agency and Florida Department of Environmental Protection water quality standard. Only in January is the average monthly dissolved oxygen concentration higher than 5 mg L(-1).

No abstract

A numerical, two-dimensional hydrodynamic model of the Mississippi River, from Thebes, IL, to Tiptonville, TN (128 miles/206 km), was developed using the Adaptive Hydraulics model. The study objective assessed current patterns and flow distributions and their possible impacts on navigation due to Birds Point New Madrid Floodway (BPNMF) operations and the Len Small (LS) levee break. The model was calibrated to stage, discharge, and velocity data for the 2011, 2015–2016, and 2017 floods. The calibrated model was used to run four scenarios, with the BPNMF and the LS breach alternately active/open and inactive/closed. Effects from the LS breach being open are increased river velocities upstream of the breach, decreased velocities from the breach to Thompson Landing, no effects on velocity below the confluence, and cross-current velocities greater than 3.28 ft/s (1.0 m/s) within 1186.8 ft (60 m) of the bankline revetment. Effects from BPNMF operation are increased river velocities above the confluence, decreased velocities from the BPNMF upper inflow crevasse (Upper Fuseplug) to New Madrid, cross-current velocities greater than 1.5 ft/s (0.5 m/s) only near the right bank where flow re-enters the river from the BPNMF lower inflow/outflow crevasse Number 2 (Lower Fuseplug) and St. Johns Bayou.