Geology topics

Lars E. Soderqvist

Publications and source records attributed to Lars E. Soderqvist.

6 recordsLinked to original sources

USGS2016

Flow characteristics and salinity patterns of tidal rivers within the northern Ten Thousand Islands, southwest Florida, water years 2007–14

Freshwater flow to the Ten Thousand Islands estuary has been altered by the construction of the Tamiami Trail and the Southern Golden Gate Estates. The Picayune Strand Restoration Project, which is associated with the Comprehensive Everglades Restoration Plan, has been implemented to improve freshwater delivery to the Ten Thousand Islands estuary by removing hundreds of miles of roads, emplacing hundreds of canal plugs, removing exotic vegetation, and constructing three pump stations. Quantifying the tributary flows and salinity patterns prior to, during, and after the restoration is essential to assessing the effectiveness of upstream restoration efforts. Tributary flow and salinity patterns during preliminary restoration efforts and prior to the installation of pump stations were analyzed to provide baseline data and preliminary analysis of changes due to restoration efforts. The study assessed streamflow and salinity data for water years 1 2007–2014 for the Faka Union River (canal flow included), East River, Little Wood River, Pumpkin River, and Blackwater River. Salinity data from the Palm River and Faka Union Boundary water-quality stations were also assessed. Faka Union River was the dominant contributor of freshwater during water years 2007–14 to the Ten Thousand Islands estuary, followed by Little Wood and East Rivers. Pumpkin River and Blackwater River were the least substantial contributors of freshwater flow. The lowest annual flow volumes, the highest annual mean salinities, and the highest percentage of salinity values greater than 35 parts per thousand (ppt) occurred in water year 2011 at all sites with available data, corresponding with the lowest annual rainfall during the study. The highest annual flow volumes and the lowest percentage of salinities greater than 35 ppt occurred in water year 2013 for all sites with available data, corresponding with the highest rainfall during the study. In water year 2014, the percentage of monitored annual flow contributed by East River increased and the percentage of flow contributed by Faka Union River decreased, compared to the earlier years. No changes in annual flow occurred at any sites west of Faka Union River. No changes in the relative flow contributions were observed during the wet season; however, the relative amounts of streamflow increased during the dry season at East River in 2014. East River had only 1 month of negative flow in 2014 compared to 6 months in 2011 and 7 months in 2008. Higher dry season flows in East River may be in response to restoration efforts. The sites to the west of Faka Union River had higher salinities on average than Faka Union River and East River. Faka Union River had the highest range in salinities, and Faka Union Boundary had the lowest range in salinities. Pumpkin River was the tributary with the lowest range in salinities. 1 Water year is defined as the 12-month period from October 1, for any given year, through September 30 of the following year.

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USGS2016

Effects of variations in flow characteristics through W.P. Franklin Lock and Dam on downstream water quality in the Caloosahatchee River Estuary and in McIntyre Creek in the J.N. “Ding” Darling National Wildlife Refuge, southern Florida, 2010–13

The U.S. Geological Survey studied water-quality trends at the mouth of McIntyre Creek, an entry point to the J.N. “Ding” Darling National Wildlife Refuge, to investigate correlations between flow rates and volumes through the W.P. Franklin Lock and Dam and water-quality constituents inside the refuge from March 2010 to December 2013. Outflow from Lake Okeechobee, and flows from Franklin Lock, tributaries to the Caloosahatchee River Estuary, and the Cape Coral canal system were examined to determine the sources and quantity of water to the study area. Salinity, temperature, dissolved-oxygen concentration, pH, turbidity, and chromophoric dissolved organic matter fluorescence (FDOM) were measured during moving-boat surveys and at a fixed location in McIntyre Creek. Chlorophyll fluorescence was also recorded in McIntyre Creek. Water-quality surveys were completed on 20 dates between 2011 and 2014 using moving-boat surveys. Franklin Lock contributed the majority of flow to the Caloosahatchee River. Between 2010 and 2013, the monthly mean flow rate at Franklin Lock ranged from 29 cubic feet per second in May 2011 to 10,650 cubic feet per second in August 2013. Instantaneous near-surface salinity in McIntyre Creek ranged from 12.9 parts per thousand on September 26, 2013, to 37.9 parts per thousand on June 27, 2011. Salinity in McIntyre Creek decreased with increasing flow rate through Franklin Lock. Flow rates through Franklin Lock explained 61 percent of the variation in salinity in McIntyre Creek. Salinity data from moving-boat surveys also indicate that an increase in flow rate at Franklin Lock decreases salinity in the Caloosahatchee River Estuary, and a reduction or elimination in flow increases salinity. The FDOM in McIntyre Creek was positively correlated with flow at Franklin Lock, and 54 percent of the variation in FDOM can be attributed to the flow rate through Franklin Lock. Data from moving-boat surveys indicate that FDOM increases when flow volume from Franklin Lock increases. The highest FDOM recorded during a survey was at Billy’s Creek. Chlorophyll fluorescence was positively correlated with flow at Franklin Lock, with 23 percent of the variation explained by the flow rate at Franklin Lock. An increase in flow rate at Franklin Lock resulted in a decrease in pH (21 percent of variation explained by flow rates). Data from the pH surveys indicate an increase in pH with distance from Franklin Lock. Turbidity and dissolved oxygen near the surface in McIntyre Creek were not correlated with flow rate at Franklin Lock. Moving-boat surveys did not document a change in turbidity or dissolved oxygen with a change in distance from the Franklin Lock. Correlations between Franklin Lock flow rate and water quality in McIntyre Creek indicate that releases at Franklin Lock affect water quality in the Caloosahatchee River Estuary and Ding Darling Refuge.

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USGS2014

Flow monitoring along the western Tamiami Trail between County Road 92 and State Road 29 in support of the Comprehensive Everglades Restoration Plan, 2007-2010

The construction of U.S. Highway 41 (Tamiami Trail), the Southern Golden Gate Estates development, and the Barron River Canal has altered the flow of freshwater to the Ten Thousand Islands estuary of Southwest Florida. Two restoration projects, the Picayune Strand Restoration Project and the Tamiami Trail Culverts Project, both associated with the Comprehensive Everglades Restoration Plan, were initiated to address this issue. Quantifying the flow of freshwater to the estuary is essential to assessing the effectiveness of these projects. The U.S. Geological Survey conducted a study between March 2006 and September 2010 to quantify the freshwater flowing under theTamiami Trail between County Road 92 and State Road 29 in southwest Florida, excluding the Faka Union Canal (which is monitored by South Florida Water Management District). The study period was after the completion of the Tamiami Trail Culverts Project and prior to most of the construction related to the Picayune Restoration Project. The section of the Tamiami Trail that was studied contains too many structures (35 bridges and 16 culverts) to cost-effectively measure each structure on a continuous basis, so the area was divided into seven subbasins. One bridge within each of the subbasins was instrumented with an acoustic Doppler velocity meter. The index velocity method was used to compute discharge at the seven instrumented bridges. Periodic discharge measurements were made at all structures, using acoustic Doppler current profilers at bridges and acoustic Doppler velocity meters at culverts. Continuous daily mean values of discharge for the uninstrumented structures were calculated on the basis of relations between the measured discharge at the uninstrumented stations and the discharge and stage at the instrumented bridge. Estimates of daily mean discharge are available beginning in 2006 or 2007 through September 2010 for all structures. Subbasin comparison is limited to water years 2008–2010. The Faka Union Canal contributed more than half (on average 60 percent) of the flow under the Tamiami Trail between State Road 29 and County Road 92 during water years 2008–2010. During water years 2008–2010, an average 9 percent of the flow through the study area came from west of the Faka Union Canal and an average 31 percent came from east of the Faka Union Canal. Flow data provided by this study serve as baseline information about the seasonal and spatial distribution of freshwater flow under the Tamiami Trail between County Road 92 and State Road 29, and study results provide data to evaluate restoration efforts.

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USGS2010

Temperature inverted haloclines provide winter warm-water refugia for manatees in southwest Florida

Florida manatees ( Trichechus manatus latirostris ) overwintering in the Ten Thousand Islands and western Everglades have no access to power plants or major artesian springs that provide warm-water refugia in other parts of Florida. Instead, hundreds of manatees aggregate at artificial canals, basins, and natural deep water sites that act as passive thermal refugia (PTR). Monitoring at two canal sites revealed temperature inverted haloclines, which provided warm salty bottom layers that generally remained above temperatures considered adverse for manatees. At the largest PTR, the warmer bottom layer disappeared unless significant salt stratification was maintained by upstream freshwater inflow over a persistent tidal wedge. A detailed three-dimensional hydrology model showed that salinity stratification inhibited vertical convection induced by atmospheric cooling. Management or creation of temperature inverted haloclines may be a feasible and desirable option for resource managers to provide passive thermal refugia for manatees and other temperature sensitive aquatic species.

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USGS2010

Seasonal and Spatial Distribution of Freshwater Flow and Salinity in the Ten Thousand Islands Estuary, Florida, 2007-2009

The watershed of the Ten Thousand Islands (TTI) estuary has been substantially altered through the construction of canals and roads for the Southern Golden Gate Estates (SGGE), Barron River Canal, and U.S. 41 (Tamiami Trail). Two restoration projects designed to improve freshwater delivery to the estuary are the Picayune Strand Restoration Project, which includes the Southern Golden Gate Estates, and the Tamiami Trail Culverts Project; both are part of the Comprehensive Everglades Restoration Plan. To address hydrologic information needs critical for monitoring the effects of these restoration projects, the U.S. Geological Survey initiated a study in October 2006 to characterize freshwater outflows from the rivers, internal circulation and mixing within the estuary, and surface-water exchange between the estuary and Gulf of Mexico. The effort is conducted in cooperation with the South Florida Water Management District and complemented by monitoring performed by the Rookery Bay National Estuarine Research Reserve. Surface salinity was measured during moving boat surveys using a flow-through system that operated at planing speeds averaging 20 miles per hour. The data were logged every 10 seconds by a data recorder that simultaneously logged location information from a Global Positioning System. The major rivers, bays, and nearshore Gulf of Mexico region of the TTI area were surveyed in approximately 5 hours by two boats traversing about 200 total miles. Salinity and coordinate data were processed using inverse distance weighted interpolation to create salinity contour maps of the entire TTI region. Ten maps were created from salinity surveys performed between May 2007 and May 2009 and illustrate the dry season, transitional, and wet season salinity patterns of the estuarine rivers, inner bays, mangrove islands, and Gulf of Mexico boundary. The effects of anthropogenic activities are indicated by exceptionally low salinities associated with point discharge into the estuary from the Faka Union Canal and Barron River during the wet season. Low salinities in Faka Union Bay may cause reduced diversity and density of submerged aquatic vegetation, fish, and benthic organisms compared with neighboring Fakahatchee Bay. The Faka Union Canal System reduced the size of the watershed for the western TTI estuary, resulting in increased wet season salinities compared to those for the eastern TTI estuary, the watershed of which is composed of the relatively pristine Fakahatchee Strand Preserve State Park. Minimal river discharge and high evaporation caused hypersaline conditions to develop throughout the entire TTI region during the dry season. The 2007-2008 drought and passage of Tropical Storm Fay on August 18-19, 2008, demonstrated the effects of seasonal rainfall on salinity patterns, with substantially higher salinities observed during the 2007 wet season compared to those for the 2008 wet season. The salinity maps, coupled with data from the monitoring stations, provide baseline information of seasonal and spatial distribution of freshwater flow and salinity in the TTI estuary, and a means of monitoring the effects of restoration in improving freshwater delivery to the estuary.

Data Series↗

USGS2007

Monitoring the storm tide of Hurricane Wilma in southwestern Florida, October 2005

Temporary monitoring stations employing non-vented pressure transducers were used to augment an existing U.S. Geological Survey coastal monitoring network to document the inland water levels related to the storm tide of Hurricane Wilma on the southwestern coast of Florida. On October 22, 2005, an experimental network consisting of 30 temporary stations was deployed over 90 miles of coastline to record the magnitude, extent, and timing of hurricane storm tide and coastal flooding. Sensors were programmed to record time, temperature, and barometric or water pressure. Water pressure was adjusted for changes in barometric pressure and salinity, and then converted to feet of water above the sensor. Elevation surveys using optical levels were conducted to reference storm tide water-level data and high-water marks to the North American Vertical Datum of 1988 (NAVD 88). Storm tide water levels more than 5 feet above NAVD 88 were recorded by sensors at several locations along the southwestern Florida coast. Temporary storm tide monitoring stations used for this effort have demonstrated their value in: (1) furthering the understanding of storm tide by allowing the U.S. Geological Survey to extend the scope of data collection beyond that of existing networks, and (2) serving as backup data collection at existing monitoring stations by utilizing nearby structures that are more likely to survive a major hurricane.

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