Search USGS⌕ Search

Geology topics

M. R. Darst

Publications and source records attributed to M. R. Darst.

5 recordsLinked to original sources
USGS2003

Forest Types in the Lower Suwannee River Floodplain, Florida?-A Report and Interactive Map

A map of forest types in the lower Suwannee River floodplain, Florida, was created during a study conducted from 1996 to 2000 by the U.S. Geological Survey in cooperation with the Suwannee River Water Management District. The map is presented with this report on a compact disc with interactive viewing software. The forest map can be used by scientists for ecological studies in the floodplain based on land cover types and by landowners and management personnel making land use decisions. The study area is the 10-year floodplain of the lower Suwannee River from its confluence with the Santa Fe River to the lower limit of forests near the Gulf of Mexico. The floodplain is divided into three reaches: riverine (non-tidal), upper tidal, and lower tidal, due to changes in hydrology, vegetation, and soils with proximity to the coast. The 10-year floodplain covers about 21,170 hectares; nearly 88 percent of this area (18,580 hectares) is mapped as 14 major forest types. Approximately 29 percent (5,319 hectares) of these forests have been altered by agriculture or development. About 75 percent of the area of major forest types (13,994 hectares) is wetland forests and about 25 percent (4,586 hectares) is upland forests. Tidal wetland forests (8,955 hectares) cover a much greater area than riverine wetland forests (5,039 hectares). Oak/pine upland forests are present in the riverine and upper tidal reaches of the floodplain on elevations that are inundated only briefly during the highest floods. High bottomland hardwoods are present on the higher levees, ridges, and flats of the riverine reach where soils are usually sandy. Low bottomland hardwood forests are present in the riverine reach on swamp margins and low levees and flats that are flooded continuously for several weeks or longer every 1 to 3 years. Riverine swamps are present in the lowest and wettest areas of the non-tidal floodplain that are either inundated or saturated most of the time. Upper tidal bottomland hardwood forests are present on sandy soils on high flats and in transitional areas between upland forests and swamps. Upper tidal mixed forests are found on low levees or between swamps and higher forest types. Upper tidal swamps are present at elevations below median monthly high stage and usually have surface soils that are permanently saturated mucks. Lower tidal hammocks are found on higher elevations that do not receive regular tidal inundation but have a high water table and are briefly inundated by storm surges several times a decade. Lower tidal mixed forests include swamps with numerous small hummocks or less common larger hummocks. Lower tidal swamps are found on deep muck soils that are below the elevation of the median daily or monthly high stage. Seven additional land cover types (2,590 hectares) are mapped. Water in the main channel of the lower Suwannee River (1,767 hectares) was mapped separately from open water in the floodplain (239 hectares). Other land cover types are: seepage slopes (70 hectares), isolated forested wetlands (19 hectares), marshes upstream of the tree line (505 hectares), beds of emergent aquatic vegetation (21 hectares), and floodplain glades (46 hectares)

Water-Resources Investigations Report↗
USGS2001

Location and description of transects for ecological studies in floodplain forests of the lower Suwannee River, Florida

Twelve transects were established in floodplain forests along the lower Suwannee River, Florida, as the principal data collection sites for a comprehensive study conducted by the U.S. Geological Survey and the Suwannee River Water Management District from 1996 to 2001. Data collected along the 12 transects included hydrologic conditions, land-surface elevations, soils, and vegetation of floodplain forests in relation to river flow. Transect locations are marked in the field with permanent markers at approximately 30 meter intervals. Detailed descriptions of the 12 transects and their locations are provided so that they can be used for future ecological studies. Descriptions of the transects include contact information necessary for access to the property on which the transects are located, maps showing transect locations and routes from the nearest city or major road, small scale maps of each transect showing marker locations, latitude and longitude of each marker, compass bearings of each transect line and graphs showing land-surface elevations of the transect with marker locations.

Open-File Report↗
USGS1996

Environmental setting and factors that affect water quality in the Georgia-Florida Coastal Plain study unit

The Georgia-Florida Coastal Plain study unit covers an area of nearly 62,000 square miles in the southeastern United States, mostly in the Coastal Plain physiographic province. Land resource provinces have been designated based on generalized soil classifications. Land resource provinces in the study area include: the Coastal Flatwoods, the Southern Coastal Plain, the Central Florida Ridge, the Sand Hills, and the Southern Piedmont. The study area includes all or parts of seven hydrologic subregions: the Ogeechee-Savannah, the Altamaha- St.Marys, the Suwannee, the Ochlockonee, the St. Johns, the Peace-Tampa Bay, and the Southern Florida. The primary source of water for public supply in the study area is ground water from the Upper Floridan aquifer. In 1990, more than 90 percent of the 2,888 million gallons per day of ground water used came from this aquifer. The population of the study area was 9.3 million in 1990. The cities of Jacksonville, Orlando, St. Petersburg, Tallahassee, and Tampa, Florida, and parts of Atlanta and Savannah, Georgia, are located in the study area. Forest and agricultural areas are the most common land uses in the study area, accounting for 48 percent and 25 percent of the study area, respectively. Climatic conditions range from temperate in Atlanta, Georgia, where mean annual temperature is about 61.3 degrees Fahrenheit, to subtropical in Tampa, Florida, where mean annual temperature is about 72.4 degrees Fahrenheit. Long-term average precipitation (1961-90) ranges from 43.9 inches per year in Tampa, Florida, and 44.6 in Macon, Georgia, to 65.7 inches per year in Tallahassee, Florida. Floods in the study area result from frontal systems, hurricanes, tropical storms, or severe thunderstorms. Droughts are not common in the study area,especially in the Florida part of the study area due to extensive maritime exposure. The primary physical and cultural characteristics in the study area include physiography, soils and land resource provinces, geologic setting, ground-water systems, surface- water systems, climate, floods, droughts, population, land use, and water use. Factors affecting water quality in the study area are land use (primarily urban and agricultural land uses), water use in coastal areas, hydrogeology, ground-water/surface-water interaction, geology, and climate. Surface-water quality problems in urban areas have occurred in the Ogeechee, Canoochee, Ocmulgee, St. Marys, Alapaha, Withlacoochee (north), Santa Fe, Ochlockonee, St. Johns, and Oklawaha Rivers and include nitrogen and phosphorus loading, low dissolved oxygen, elevated bacteria, sediment, and turbidity, and increased concentrations of metals. In agricultural areas, surface-water quality problems include elevated nitrogen and phosphorus concentrations, erosion, and sedimentation and have occurred in the Ocmulgee, St. Marys, Santa Fe, Ochlockonee, St. Johns, Oklawaha, Withlacoochee (South), Hillsborough, and Alafia Rivers. Ground water-quality problems such as saltwater intrusion have occurred mostly in coastal areas and were caused by excessive withdrawals.

Florida, Georgia↗
USGS1993

Hydrology, vegetation, and soils of four north Florida River flood plains with an evaluation of state and federal wetland determinations

A study of hydrologic conditions, vegetation, and soils was made in wetland forests of four north Florida streams from 1987 to 1990. The study was conducted by the U.S. Geological Survey in cooperation with the Florida Department of Environmental Regulation to support State and Federal efforts to improve wetland delineation methodology in flood plains. Plant communities and soils were described and related to topographic position and long-term hydrologic conditions at 10 study plots located on 4 streams. Detailed appendixes give average duration, frequency, and depth of flooding; canopy, subcanopy, and ground-cover vegetation; and taxonomic classification, series, and profile descriptions of soils for each plot. Topographic relief, range in stage, and depth of flooding were greatest on the alluvial flood plain of the Ochlockonee River, the largest of the four streams. Soils were silty in the lower elevations of the flood plain, and tree communities were distinctly different in each topographic zone. The Aucilla River flood plain was dominated by levees and terraces with very few depressions or low backwater areas. Oaks dominated the canopy of both lower and upper terraces of the Aucilla flood plain. Telogia Creek is a blackwater stream that is a major tributary of the Ochlockonee River. Its low, wet flood plain was dominated by Wyssa ogeche (Ogeechee tupelo) trees, had soils with mucky horizons, and was inundated by frequent floods of very short duration. The St. Marks River, a spring-fed stream with high base flow, had the least topographic relief and lowest range in stage of the four streams. St. Marks soils had a higher clay content than the other streams, and limestone bedrock was relatively close to the surface. Wetland determinations of the study plots based on State and Federal regulatory criteria were evaluated. Most State and Federal wetland determinations are based primarily on vegetation and soil characteristics because hydrologic records are usually not available. In this study, plots were located near long-term gaging stations, thus wetland determinations based on plant and soil characteristics could be evaluated at sites where long-term hydrologic conditions were known. Inconsistencies among hydrology, vegetation, and soil determinations were greatest on levee communities of the Ochlockonee and Aucilla River flood plains. Duration of average annual longest flood was almost 2 weeks for both plots. The wetland species list currently used (1991) by the State lacks many ground-cover species common to forested flood plains of north Florida rivers. There were 102 ground-cover species considered upland plants by the State that were present on the nine annually flooded plots of this study. Among them were 34 species that grew in areas continuously flooded for an average of 5 weeks or more each year. Common flood-plain species considered upland plants by the State were: Hypoxis leptocarpa (yellow star-grass), and two woody vines, Brunnichia ovata (ladies' eardrops) and Campsis radican s (trumpet-creeper), which were common in areas flooded continuously for 6 to 9 weeks a year; Sebastiania fruticosa (Sebastian-bush), Chasmanthium laxum (spikegrass), and Panicum dichotomum (panic grass), which typically grew in areas flooded an average of 2 to 3 weeks or more per year; Vitis rotundifolia (muscadine) and Toxicodendron radicans (poison-ivy), usually occurring in areas flooded an average of 1 to 2 weeks a year; and Quercus virginiana (live oak) present most often in areas flooded approximately 1 week a year. Federal wetland regulations (1989) limited wetland jurisdiction to only those areas that are inundated or saturated during the growing season. However, year-round hydrologic records were chosen in this report to describe the influence of hydrology on vegetation, because saturation, inundation, or flowing water can have a variety of both beneficial and adverse effects on flood-plain vegetation at any time of the year. These effects can occur because: (1) Soil temperatures in north Florida are probably high enough in winter for anaerobic conditions to develop in saturated soils. (2) Many plants in the flood plains of north Florida are active in the nongrowing season and might be adapted to anaerobic conditions in winter. (3) Other effects of standing water, such as decreased light penetration, prevention of seed germination, and protection of seeds from herbivores; and effects of flowing water, such as scouring and deposition of sediments, seed dispersal, and mechanical injury, can occur any time of year.

Florida↗