The Experts below are selected from a list of 276 Experts worldwide ranked by ideXlab platform
Michael A. Poirrier - One of the best experts on this subject based on the ideXlab platform.
-
Acute Disturbance of Lake Pontchartrain Benthic Communities by Hurricane Katrina
Estuaries and Coasts, 2008Co-Authors: Michael A. Poirrier, Zoe Rodriguez Del Rey, Elizabeth A. SpaldingAbstract:In 2005, Hurricane Katrina produced a distinct, acute ecological disturbance of the benthic invertebrate community of Lake Pontchartrain, LA, USA. The bivalve Rangia cuneata and other community dominants were lost from 50% (815 km2) of the Lake bottom. The storm surge directly killed benthic organisms and produced salinity stratification that caused episodes of detrimental low dissolved oxygen concentration at depths >3.7 m. Past disturbance of the bottom by shell dredging and intrusion of higher salinity bottom water through deep shipping channels appears to have contributed to the severity of this impact. Colonization by tolerant opportunistic taxa occurred, but low rainfall after Katrina has slowed the recovery of the typical rangia community. A decrease in water transparency and an increase in turbidity and chlorophyll a were associated with the loss of clam biomass. Other hurricanes may have produced less obvious but similar effects on smaller spatial and temporal scales.
-
Effects of the 1997 Bonnet Carré Spillway Opening on Infaunal Macroinvertebrates in Lake Pontchartrain, Louisiana
Journal of Coastal Research, 2007Co-Authors: Amanda J. Brammer, Zoe Rodriguez Del Rey, Elizabeth A. Spalding, Michael A. PoirrierAbstract:Abstract The Bonnet Carre Spillway was constructed in 1931 to divert floodwater from the Mississippi River into Lake Pontchartrain, an oligohaline estuary near New Orleans, Louisiana. The spillway was opened from March 17 through April 18, 1997. Infaunal macroinvertebrate population, surface and bottom salinity, and dissolved oxygen data were examined to determine the effects of this diversion. These data were obtained from November 1996 through November 1998 from five sites on an east-to-west transect across Lake Pontchartrain. A community composed of oligohaline taxa persisted during the freshwater period, but changes in dominance, and to a lesser extent composition, occurred over time and among sites. There was a pronounced spatial effect related to the distance of the sites from the spillway and from tidal passes. Based on decreases in species diversity (H′), abundance, and the number of taxa, it appears that the opening had a deleterious impact on the benthos. The cause of these changes cannot be att...
-
Response of submersed aquatic vegetation (SAV) in Lake Pontchartrain, Louisiana to the 1997–2001 El Niño Southern Oscillation shifts
Estuaries, 2005Co-Authors: Michael A. PoirrierAbstract:Lake Pontchartrain is a large, shallow, low salinity estuary north of New Orleans, Louisiana. It is a water quality impaired system with restoration efforts in progress. One restoration goal is the reestablishment of historic submersed aquatic vegetation (SAV; Vallisneria americana Michx. and Ruppia maritima L.), which has been in a state of decline since first studied in 1953. Annual SAV surveys and monthly water quality monitoring were conducted at four to five sites from 1996 through 2003 to evaluate trends and determine the causes of SAV change. We found a rapid increase in the distribution and abundance of R. maritima in 1999 that persisted through 2002. An El Niño Southern Oscillation shift occurred between 1997 and 2001, which produced a drought in southern Louisiana as an ancillary effect of La Niña. This study was conducted to investigate causal links between the El Niño to La Niña climate phase shift and SAV change. We found that salinity and water clarity increased during La Niña. Increased water clarity produced a rapid increase in the euryhaline species R. maritima in deeper water and at historic sites where SAV had not been found since 1953. As salinity increased, the freshwater species V. americana and Myriophyllum spicatum L. declined, and Najas guadalupensis (Spreng.) Magnus and Potamogeton perfoliatus L. disappeared. In 2003, after the La Niña phase, salinity and water clarity decreased, R. maritima decreased, and the freshwater species increased, but P. perfoliatus was still absent. We found that salinity controlled SAV species composition, and water clarity controlled SAV colonization depth (Z_col=2.3/K_d). Our study demonstrated that climatic shifts cause cyclic changes in Lake Pontchartrain SAV and that restoration could be accomplished by improving water clarity. Due to the sensitivity of SAV to environmental change, similar responses to short-term and long-term climate changes should occur in other estuarine systems.
-
Response of submersed aquatic vegetation (SAV) in Lake Pontchartrain, Louisiana to the 1997–2001 El Niño Southern Oscillation shifts
Estuaries, 2005Co-Authors: Hyun Jung Cho, Michael A. PoirrierAbstract:Lake Pontchartrain is a large, shallow, low salinity estuary north of New Orleans, Louisiana. It is a water quality impaired system with restoration efforts in progress. One restoration goal is the reestablishment of historic submersed aquatic vegetation (SAV; Vallisneria americana Michx. and Ruppia maritima L.), which has been in a state of decline since first studied in 1953. Annual SAV surveys and monthly water quality monitoring were conducted at four to five sites from 1996 through 2003 to evaluate trends and determine the causes of SAV change. We found a rapid increase in the distribution and abundance of R. maritima in 1999 that persisted through 2002. An El Niño Southern Oscillation shift occurred between 1997 and 2001, which produced a drought in southern Louisiana as an ancillary effect of La Niña. This study was conducted to investigate causal links between the El Niño to La Niña climate phase shift and SAV change. We found that salinity and water clarity increased during La Niña. Increased water clarity produced a rapid increase in the euryhaline species R. maritima in deeper water and at historic sites where SAV had not been found since 1953. As salinity increased, the freshwater species V. americana and Myriophyllum spicatum L. declined, and Najas guadalupensis (Spreng.) Magnus and Potamogeton perfoliatus L. disappeared. In 2003, after the La Niña phase, salinity and water clarity decreased, R. maritima decreased, and the freshwater species increased, but P. perfoliatus was still absent. We found that salinity controlled SAV species composition, and water clarity controlled SAV colonization depth (Z_col=2.3/K_d). Our study demonstrated that climatic shifts cause cyclic changes in Lake Pontchartrain SAV and that restoration could be accomplished by improving water clarity. Due to the sensitivity of SAV to environmental change, similar responses to short-term and long-term climate changes should occur in other estuarine systems.
-
Seasonal growth and reproduction of Ruppia maritima L. s.l. in Lake Pontchartrain, Louisiana, USA
Aquatic Botany, 2005Co-Authors: Hyun Jung Cho, Michael A. PoirrierAbstract:Ruppia maritima L. s.l. is an important submerged aquatic plant in Lake Pontchartrain, a water quality impaired oligohaline estuary located north of New Orleans, Louisiana, USA. Efforts to restore Lake Pontchartrain are in progress, and a major restoration goal is the re-establishment of historic submerged macrophyte beds that have declined since first studied in 1953. This study was part of a long-term monitoring program to distinguish natural from anthropogenic causes of macrophyte population changes. Ruppia populations were monitored monthly for a 2-year period to obtain information on seasonal growth, peak biomass periods, flowering, seed production, and germination. We found that Lake Pontchartrain R. maritima had relatively high peak biomass and two seasonal peaks of biomass and flowering due to high water temperature and absence of competition from other macrophytes. However, biomass peaks were often disrupted by storms. Shoot biomass was high from May through November, and low from December through April. Spring shoot growth from seeds, roots, and rhizomes was rapid. Plants matured and produced abundant inflorescences and seeds between May and October. Reproductive shoots bearing seeds were detached in May and June. Remaining shoots formed dense beds through vegetative propagation during the summer. Turion production occurred during the winter.
Eddie Weeks - One of the best experts on this subject based on the ideXlab platform.
-
Storm surge induced flux through multiple tidal passes of Lake Pontchartrain estuary during Hurricanes Gustav and Ike
Estuarine Coastal and Shelf Science, 2010Co-Authors: Eddie Weeks, Brian W. BlanchardAbstract:Abstract In September 2008, Hurricanes Gustav and Ike generated major storm surges which impacted the Lake Pontchartrain estuary in Louisiana. This paper presents analyses of in situ measurements acquired during these storm events. The main data used in the analyses were from three bottom mounted moorings equipped with conductivity, temperature, and depth sensors, acoustic Doppler current profilers (ADCPs), and a semi-permanent laterally mounted horizontal acoustic Doppler profiler (ADP). These moorings were deployed in the three major tidal channels that connect Lake Pontchartrain with the coastal ocean. A process similar to tidal straining was observed: the vertical shear of the horizontal velocity was negligible during the inundation stage, but a shear of 0.8 m/s over a less than 5 m water column was recorded during the receding stage, 2–3 times the normal tidal oscillations. The surge reached its peak in the Industrial Canal 1.4–2.1 h before those in the other two channels. The inward flux of water lasted for a shorter time period than that of the outward flux. The inward flux was also observed to have much smaller magnitude than the outward flux (∼960–1200 vs. 2100–3100 million m 3 ). The imbalance was believed to have been caused by the additional water into Lake Pontchartrain through some small rivers and inundation over the land plus rainfall from the hurricanes. The flux through the Industrial Canal was 8–12%, while the flux through the other two tidal passes ranged between 17% and 70% of the total, but mostly split roughly half-half of the remaining (∼88–92% of the total).
-
circular plumes in Lake Pontchartrain estuary under wind straining
Estuarine Coastal and Shelf Science, 2008Co-Authors: Nan D. Walker, Alex J. Mccorquodale, Ioannis Y. Georgiou, Aixin Hou, Edward A. Laws, Harry H. Roberts, Eddie Weeks, Jessica CrochetAbstract:Circular shaped density plumes of low turbidity, low fecal indicator (Escherichia coli and enterococci) concentrations, and high salinity have been observed near the Industrial Canal in Lake Pontchartrain, north of the City of New Orleans. A conceptual model in polar coordinates and a numerical model are developed, together with data analysis, to illustrate the dense plume. It is demonstrated that the northward expansion of the plume occurs under northerly winds. The northward expansion of the plume occurs under northerly winds that drive downwind flow at the surface and upwind radial flow at the bottom. Northerly wind-induced straining, similar to tidal straining, promotes vertical stratification. As a result, the water becomes stratified near a thin bottom layer (<1 m), within which density currents are facilitated. The stability of the stratified plume suppresses wind-induced turbulent mixing inside the plume. The bottom water outside of the plume is more effectively stirred by the wind, the result being that the suspended sediment concentration outside of the plume area is much higher than inside. This contrast in mixing makes the plume visible from the surface by satellites even though the stratification is at the bottom. Laterally, wind stress produces a torque (vorticity) in areas of non-uniform depth such that upwind flow is developed in deep water and downwind flow in shallow water. The continuity requirement produces an upwind flow along the axis of the Industrial Canal (IC). The upwind flow is balanced by the downwind flow over the shallower peripheral areas along the coast.
-
Circular plumes in Lake Pontchartrain estuary under wind straining
Estuarine Coastal and Shelf Science, 2008Co-Authors: Nan D. Walker, Ioannis Y. Georgiou, J. Alex Mccorquodale, Aixin Hou, Edward A. Laws, Harry H. Roberts, Eddie Weeks, Jessica CrochetAbstract:Circular shaped density plumes of low turbidity, low fecal indicator (Escherichia coli and enterococci) concentrations, and high salinity have been observed near the Industrial Canal in Lake Pontchartrain, north of the City of New Orleans. A conceptual model in polar coordinates and a numerical model are developed, together with data analysis, to illustrate the dense plume. It is demonstrated that the northward expansion of the plume occurs under northerly winds. The northward expansion of the plume occurs under northerly winds that drive downwind flow at the surface and upwind radial flow at the bottom. Northerly wind-induced straining, similar to tidal straining, promotes vertical stratification. As a result, the water becomes stratified near a thin bottom layer (
Ronald D. Delaune - One of the best experts on this subject based on the ideXlab platform.
-
Physico-chemical forms of copper in water and sediments of Lake Pontchartrain basin, USA.
Chemosphere, 2017Co-Authors: Zengqiang Zhang, Jim J. Wang, Amjad Ali, Ronald D. DelauneAbstract:Abstract In this study, one of the largest estuaries in the Gulf Coast of USA was investigated for Cu forms and fractionations. Both the water and sediment samples in subsegments of the Lake Pontchartrain basin were collected and Cu forms in dissolved phase and sediment phase were analyzed. The BCR sequential extraction procedure was used to extract Cu in exchangeable, reducible, oxidizable and residual fractions in sediments. The results showed that the residual fraction of Cu was a major contributor in Tangipahoa River and I-10 Bridge sediments, while the residual and oxidizable fractions in the case of oil refinery sediments. Cu partitioning in Lake Pontchartrain basin water showed the decreasing trend of inert > labile > organic in both spring and summer. The release of Cu from the sediments into the water column was greater in summer as compared to spring and vice versa. Lower temperature helps in the adsorption of Cu on the surface of sediments in early spring due to low disturbance and temperature.
-
Heavy metal distribution and water quality characterization of water bodies in Louisiana's Lake Pontchartrain Basin, USA.
Environmental monitoring and assessment, 2016Co-Authors: Zengqiang Zhang, Jim J. Wang, Amjad Ali, Ronald D. DelauneAbstract:The seasonal variation in physico-chemical properties, anions, and the heavy metal (Cd, Co, Cr, Cu, Mn, Ni, Pb, and Zn) concentration was evaluated in water from nine different rivers in Lake Pontchartrain Basin, Louisiana, USA. The water quality parameters were compared with toxicity reference values (TRV), US Environmental Protection Agency (USEPA) drinking/aquatic life protection, and WHO standards. Among physico-chemical properties, pH, DO, and turbidity were high during spring, while, EC, temperature, and DOC were high during summer and vice versa. The anion study revealed that the concentrations of F−, Cl−, and NO3− were higher during summer and Br− and SO4− were higher during spring. Our research findings showed anion concentration decreased in the order of Cl− > SO4− > NO3− > Br− > F−, in accordance with the global mean anion concentration. The dissolved heavy metals (Cd, Co, Cr, Cu, Mn, Ni, Pb) except Zn were higher during spring than summer. None of the rivers showed any Cd pollution for both seasons. Co showed higher concentrations in Amite River, Mississippi River, Industrial Canal, and Lacombe Bayou during summer. The Cr concentration was higher than WHO drinking water standards, implicating water unsuitability for drinking purposes in all the rivers associated with the Lake Pontchartrain Basin. Cu showed no pollution risk for the study area. Mn and Co were similar to concentration in Lacombe Bayou, Liberty Bayou, Blind River, and Industrial Canal. Mn levels were greater than WHO standards for the Tickfaw River, Tangipahoa River, and Blind River in both seasons. Blind River, Tangipahoa River, Tickfaw River, and Amite River will require more monitoring for determining possible Mn pollution. Ni content in river water during both seasons showed low pollution risk. Liberty Bayou and Industrial Canal concentrations were closer to the WHO regulatory standards, indicating possible risk of Pb pollution in these water bodies. The Zn content was near the USEPA aquatic life standards in summer for all water bodies. None of the rivers showed any risk associated with Cd, Co, Cu, and Ni levels but medium to higher risk to aquatic life from Cr and Zn for both seasons for most of the rivers. Metal fractionation revealed the decreasing order of inert > labile > organic. The high inert fraction in the rivers under study reflects the major contribution of natural sources in Lake Pontchartrain Basin. The labile and organic forms of Cd, Cu, Ni, and Zn pose potential higher risk to the aquatic life in the Lake Pontchartrain Basin.
-
Heavy metals and metalloid contamination in Louisiana Lake Pontchartrain Estuary along I-10 Bridge
Transportation Research Part D: Transport and Environment, 2016Co-Authors: Zengqiang Zhang, Jim J. Wang, Amjad Ali, Ronald D. DelauneAbstract:Abstract In this study, HMs concentration in sediments and water from the Lake Pontchartrain estuary along the I-10 Bridge were investigated in two seasons to evaluate the level of contamination and to assess the effect of vehicular traffic. Vehicular traffic has led to HMs such as As, Cd, Cr, Pb, Zn, Ni, and Cu accumulation in sediments along the bridge. The HMs content in water especially in summer increased due to high temperature which led to release of HMs from the sediments. The level of pollution attributed to anthropogenic activities was evaluated using several pollution indicators. The overall HMs bioavailability and EFs was mostly high in summer and the concentration of the HMs in both sediments and water was highly influenced by the season and the distance from the highways. The content of As and Cd in Lake sediments were higher than the background values (BGV) for both seasons (spring and summer), and Cr and Pb in sediments were higher than the BGV in most sampling points in the spring. According to Sediments Quality Guidelines (SQGs), heavy metals except for As have low biotoxicity, and As could potentially result in harmful effects on the aquatic organisms. The relationship between As and vehicular traffic is less studied so our finding stress the need for further study on source of As in Lake Pontchartrain sediments.
-
Copper in Lake Pontchartrain bottom sediment: Relationship to sediment properties
Aquatic Ecosystem Health & Management, 2009Co-Authors: Ronald D. Delaune, Jim J. Wang, Aroon JugsujindaAbstract:Several watersheds in the Louisiana Pontchartrain Basin are listed as impaired, with dissolved Cu as one of the impairments. In this study we determine Cu levels in sediment of Lake Pontchartrain (which comprises part of one of the largest estuaries in the Gulf Coast region) which receives water from impaired watersheds. Sediment samples were collected along an 8 km sampling grid (174 sites) and analyzed for total Cu in sediment. The average Cu content in sediment was 13.6 ± 6.7 mg.kg−1 ranging from 0 to 31.5 mg.kg−1 (n = 174). Results show that there was little Cu pollution in the Lake sediment. Cu level was correlated with Al content (r = 0.888∗∗) and Fe content (r = 0.907∗∗) of sediment. Higher Cu was also found in sediment with high clay content (r = 0.429∗∗). Cu was inversely correlated with sand content of sediment (r = −0.520∗∗).
-
Pathogen indicator microbes and heavy metals in Lake Pontchartrain following Hurricane Katrina.
Environmental science & technology, 2006Co-Authors: Aixin Hou, Edward A. Laws, Robert P. Gambrell, Hee-sung Bae, Meihuey Tan, Ronald D. Delaune, Harry H. RobertsAbstract:Storm surge and several breaches of the New Orleans, Louisiana levee system caused flooding of more than 80% of the city following Hurricane Katrina in August 2005. Most of the floodwaters pumped out of the city were discharged to Lake Pontchartrain. Lake water and sediment samples were collected during September 19 to October 9, 2005 to determine the possible impact of the dewatering operation on Lake Pontchartrain. Surface water E. coli and enterococcus counts were high at stations near the mouth of the 17th Street Canal (geometric means = 6.0 × 103 CFU/100 mL and 1.7 × 102 CFU/100 mL, respectively) but decreased by factors of 40 and 5, respectively, at stations 5 km from the mouth of the canal. Priority heavy metal concentrations were generally undetectable or below U.S. EPA criterion maximum and criterion continuous concentrations. Surface sediments near the mouth of the canal contained generally higher concentrations of enterococcus, E. coli, and Al-normalized metals than points further from the cana...
Xiaobo Chao - One of the best experts on this subject based on the ideXlab platform.
-
Numerical simulation of sediment transport, phytoplankton biomass and salinity recovery processes in Lake Pontchartrain due to Bonnet Carré Spillway flood release
Ecological Engineering, 2021Co-Authors: Xiaobo Chao, Yafei Jia, A.k.m. Azad Hossain, Yaoxin ZhangAbstract:Abstract The Bonnet Carre Spillway (BCS) was constructed from 1929 to 1936 to protect the city of New Orleans from the Mississippi River floods. When the water stage of the Mississippi River is over 5.18 m of flood stage, BCS will be opened to divert the excessive flood water into the Gulf of Mexico through Lake Pontchartrain. During these flood release events, large amounts of freshwater, sediment and nutrients were discharged into the Lake and significantly affected its water quality and aquatic environment. A numerical model (CCHE2D) developed at the National Center for Computational Hydroscience and Engineering (NCCHE), the University of Mississippi, was applied to simulate the dynamic process of hydrodynamics and associated temporal and spatial distributions of sediment, salinity and phytoplankton in Lake Pontchartrain due to the BCS flood release events. Three events occurred in 1997, 2008 and 2011, representing the median, low, and high flood discharge cases, were selected for this study. The simulated results were compared with field measured data and satellite imageries obtained from USGS, US Army Crop of Engineers and NOAA, and good agreements were obtained. The effects of nutrients and suspended sediment on the growth of phytoplankton as well as the occurrence of algal bloom in the Lake were analyzed. The processes of salinity recovery in the Lake were also discussed. The results obtained from this research provide useful information for analyzing the impacts of flood release event on the aquatic ecosystems in Lake Pontchartrain.
-
Numerical Modeling of Sediment Transport and Its Effect on Algal Biomass Distribution in Lake Pontchartrain Due to Flood Release from Bonnet Carré Spillway
Journal of Geoscience and Environment Protection, 2016Co-Authors: Xiaobo Chao, Yafei Jia, A.k.m. Azad HossainAbstract:In order to protect the city of New Orleans from the Mississippi River flooding, the Bonnet Carre Spillway (BCS) was constructed from 1929 to 1936 to divert flood water from the river into Lake Pontchartrain and then into the Gulf of Mexico. During the BCS opening for flood release, large amounts of freshwater, nutrients, sediment, etc. were discharged into Lake Pontchartrain, and caused a lot of environmental problems. To evaluate the environmental impacts of the flood water on Lake ecosystems, a two-dimensional numerical model was developed based on CCHE2D and applied to simulate the flow circulation, sediment transport and algal biomass distribution in Lake Pontchartrain. The effect of sediment concentration on the growth of algae was considered in the model. The numerical model was calibrated using field measured data provided by USGS, and then it was validated by the BCS Opening Event in 1997. The simulated results were generally in good agreement with filed data and satellite imagery. The field observation and numerical model show that during the spillway opening for flood release, the sediment concentration is very high, which greatly restricts the growth of algae, so there is no algal bloom observed in the Lake. After the closure of BCS, the sediment concentration in the Lake reduces gradually, and the nutrient concentration of the Lake is still high. Under these conditions, numerical results and satellite imagery showed that the chlorophyll concentration was high and algal bloom might occur.
-
Numerical modeling of surface flow and transport phenomena with applications to Lake Pontchartrain
Lake and Reservoir Management, 2012Co-Authors: Xiaobo Chao, Yafei Jia, Sam S. Y. Wang, A.k.m. Azad HossainAbstract:Abstract This article presents the capabilities of a numerical model, CCHE2D, by using its application to study the response of a highly complex water system, Lake Pontchartrain, Louisiana, under extreme conditions of Hurricane Katrina in 2005 and the flood water release from Bonnet Carre Spillway in 1997. The numerical simulations were validated using the field data collected by the US Geological Survey and US Army Corps of Engineers, as well as satellite imagery obtained from National Oceanic and Atmospheric Administration. The close agreements obtained with technically acceptable accuracy in both field properties and trends of their spatial and temporal variations fully demonstrated this model's usefulness in predicting the hydrodynamics, sediment transport, and salinity distribution of Lakes under extreme flood forcing. This model provides a useful tool for Lake water quality management.
-
Three-Dimensional Numerical Modeling of Flow Circulations in Lake Pontchartrain
World Environmental and Water Resources Congress 2010, 2010Co-Authors: Xiaobo Chao, Yafei JiaAbstract:This paper presents the development and application of a three-dimensional numerical model for simulating the flow circulations in Lake Pontchartrain, LA. The water movements within the Lake are primarily wind and tide induced. Tidal currents influence the Lake circulations through a few narrow passages with mild amplitude of the tidal cycles. The wind and tide-induced hydrodynamics dominate transport processes in the Lake. In this study, the developed model was first verified against analytical solutions of wind-driven and tide-driven flows; then it was applied to simulate the flow fields in Lake Pontchartrain. This model was also applied to simulate Hurricane Rita induced flow fields. The simulated water surface elevation and flow currents were generally in good agreement with field measurements provided by the United States Geological Survey (USGS). This model provides a useful tool to analyze the flow currents induced by wind and tide in large natural Lakes.
A.k.m. Azad Hossain - One of the best experts on this subject based on the ideXlab platform.
-
Numerical simulation of sediment transport, phytoplankton biomass and salinity recovery processes in Lake Pontchartrain due to Bonnet Carré Spillway flood release
Ecological Engineering, 2021Co-Authors: Xiaobo Chao, Yafei Jia, A.k.m. Azad Hossain, Yaoxin ZhangAbstract:Abstract The Bonnet Carre Spillway (BCS) was constructed from 1929 to 1936 to protect the city of New Orleans from the Mississippi River floods. When the water stage of the Mississippi River is over 5.18 m of flood stage, BCS will be opened to divert the excessive flood water into the Gulf of Mexico through Lake Pontchartrain. During these flood release events, large amounts of freshwater, sediment and nutrients were discharged into the Lake and significantly affected its water quality and aquatic environment. A numerical model (CCHE2D) developed at the National Center for Computational Hydroscience and Engineering (NCCHE), the University of Mississippi, was applied to simulate the dynamic process of hydrodynamics and associated temporal and spatial distributions of sediment, salinity and phytoplankton in Lake Pontchartrain due to the BCS flood release events. Three events occurred in 1997, 2008 and 2011, representing the median, low, and high flood discharge cases, were selected for this study. The simulated results were compared with field measured data and satellite imageries obtained from USGS, US Army Crop of Engineers and NOAA, and good agreements were obtained. The effects of nutrients and suspended sediment on the growth of phytoplankton as well as the occurrence of algal bloom in the Lake were analyzed. The processes of salinity recovery in the Lake were also discussed. The results obtained from this research provide useful information for analyzing the impacts of flood release event on the aquatic ecosystems in Lake Pontchartrain.
-
Numerical Modeling of Sediment Transport and Its Effect on Algal Biomass Distribution in Lake Pontchartrain Due to Flood Release from Bonnet Carré Spillway
Journal of Geoscience and Environment Protection, 2016Co-Authors: Xiaobo Chao, Yafei Jia, A.k.m. Azad HossainAbstract:In order to protect the city of New Orleans from the Mississippi River flooding, the Bonnet Carre Spillway (BCS) was constructed from 1929 to 1936 to divert flood water from the river into Lake Pontchartrain and then into the Gulf of Mexico. During the BCS opening for flood release, large amounts of freshwater, nutrients, sediment, etc. were discharged into Lake Pontchartrain, and caused a lot of environmental problems. To evaluate the environmental impacts of the flood water on Lake ecosystems, a two-dimensional numerical model was developed based on CCHE2D and applied to simulate the flow circulation, sediment transport and algal biomass distribution in Lake Pontchartrain. The effect of sediment concentration on the growth of algae was considered in the model. The numerical model was calibrated using field measured data provided by USGS, and then it was validated by the BCS Opening Event in 1997. The simulated results were generally in good agreement with filed data and satellite imagery. The field observation and numerical model show that during the spillway opening for flood release, the sediment concentration is very high, which greatly restricts the growth of algae, so there is no algal bloom observed in the Lake. After the closure of BCS, the sediment concentration in the Lake reduces gradually, and the nutrient concentration of the Lake is still high. Under these conditions, numerical results and satellite imagery showed that the chlorophyll concentration was high and algal bloom might occur.
-
Numerical modeling of surface flow and transport phenomena with applications to Lake Pontchartrain
Lake and Reservoir Management, 2012Co-Authors: Xiaobo Chao, Yafei Jia, Sam S. Y. Wang, A.k.m. Azad HossainAbstract:Abstract This article presents the capabilities of a numerical model, CCHE2D, by using its application to study the response of a highly complex water system, Lake Pontchartrain, Louisiana, under extreme conditions of Hurricane Katrina in 2005 and the flood water release from Bonnet Carre Spillway in 1997. The numerical simulations were validated using the field data collected by the US Geological Survey and US Army Corps of Engineers, as well as satellite imagery obtained from National Oceanic and Atmospheric Administration. The close agreements obtained with technically acceptable accuracy in both field properties and trends of their spatial and temporal variations fully demonstrated this model's usefulness in predicting the hydrodynamics, sediment transport, and salinity distribution of Lakes under extreme flood forcing. This model provides a useful tool for Lake water quality management.
