Thomas M. Williams

Thomas M. Williams
Clemson University | CU · Baruch Institute of Coastal Ecology and Forest Science

About

93
Publications
16,453
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1,453
Citations
Citations since 2016
12 Research Items
444 Citations
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20162017201820192020202120220204060
20162017201820192020202120220204060
20162017201820192020202120220204060

Publications

Publications (93)
Article
In this study, we calibrated and tested the Soil Conservation Service Curve Number (SCS-CN) based Modified Sahu-Mishra-Eldo (MSME) model for predicting storm event direct runoff (Qtot) and its soil saturation coefficient α as a threshold antecedent moisture condition for partitioning into overland surface and shallow subsurface runoff components. T...
Conference Paper
Full-text available
In this study, we calibrated and tested the Soil Conservation Service Curve Number 21 (SCS-CN) based Modified Sahu-Mishra-Eldo (MSME) model for predicting storm event total direct 22 runoff (Qtot) The MSME model satisfactorily predicted the estimated Qtot_pred for three watersheds, 23 unsatisfactory for one watershed. These results demonstrate MSME...
Article
Undeveloped forested wetlands in the valleys of coastal plain rivers can play a large role in storing floodwater and attenuating river flooding. In the lower Pee Dee, Little Pee Dee, and Lynches Rivers, these wetlands played a large role in mitigating downstream flooding following Hurricane Florence. Wetland forest flood mitigation was most effecti...
Article
Over past years, extreme tropical storm events along the North and South Carolina coasts—and subsequent river flooding—have warranted the need for a better understanding of the hydrologic response to these events to protect life, property, businesses, and natural and cultural resources. Our focus in this study is the Pee Dee and Waccamaw River syst...
Poster
Full-text available
Coastal ecosystems are vulnerable to climate change and have been identified as sources of uncertainty in the global carbon budget, yet remain underrepresented in climate studies despite their potential to sequester large amounts of carbon. Here we introduce a recently established mesonet of eddy covariance towers in South Carolina, the associated...
Article
This paper examines data from 18 USGS gauges in the lower Pee Dee Basin in an effort to explain the behavior of the flooding following Hurricane Florence (2018) in Georgetown County, South Carolina. Despite record or near-record flooding in all the tributaries to the Winyah Bay estuary, water levels near the city of Georgetown were well below predi...
Chapter
Full-text available
Tidally influenced coastal forested wetlands can be divided into two broad categories, mangroves and freshwater forested wetlands. These forested wetlands perform valuable ecosystem services, and both are endangered by threats of sea level rise and land use. Understanding the mechanisms that control the distribution of tidal forests has been greatl...
Article
Full-text available
Sustainable management of forested wetlands requires an understanding of water Table (WT) dynamics affected by rainfall and evapotranspiration (ET) and management practices, designed to sustain water quality, quantity, and ecosystem functions and productivity. In this paper analysis of long-term data from four drained and six undrained sites on coa...
Article
This article compares the short-term and long-term hydrology of two typical forests in the humid Atlantic Coastal Plain, including a relatively undisturbed forest with natural drainage in South Carolina (SC) and a drained pine plantation in North Carolina (NC), using monitoring and modeling approaches. Highly dynamic outflow (O) from both of these...
Conference Paper
Full-text available
Coastal forested wetland swamps are sentinel sites for salinity intrusions associated with large tidally-influenced or storm-driven incursions of estuarine waters that may also indicate rising sea levels associated with climate change. A coastal freshwater forested wetland in coastal South Carolina has experienced dieback of freshwater forested wet...
Article
The landscape of the coastal plain of the southeastern United States is rapidly changing due to urbanization and climate-change-related impacts. In addition to the forecasted population increase, this region could experience significant changes in precipitation patterns making watershed management very challenging. In order to establish baseline da...
Article
Full-text available
Hurricanes are infrequent but influential disruptors of ecosystem processes in the southeastern Atlantic and Gulf coasts. Every southeastern forested wetland has the potential to be struck by a tropical cyclone. We examined the impact of Hurricane Hugo on two paired coastal South Carolina watersheds in terms of streamflow and vegetation dynamics, b...
Article
Full-text available
Understanding sources of streamflow and nutrient concentrations are fundamental for the assessment of pollutant loadings that can lead to water quality impairments. The objective of this study was to evaluate the discharge of three main tributaries, draining different land uses with karst features, as well as their combined influences on total nitr...
Article
Recent major wildfires may result from a combination of climate change and fuel buildup due to fire exclusion policies of the last century. Are such fires unique to the forests and climate of the 21st century or are they similar to historic fires? Historic fires are recorded primarily by eye witness accounts which seldom contain information needed...
Article
The objective of this study was to assess curve number (CN) values derived for two forested headwater catchments in the Lower Coastal Plain (LCP) of South Carolina using a three‐year period of storm event rainfall and runoff data in comparison with results obtained from CN method calculations. Derived CNs from rainfall/runoff pairs ranged from 46 t...
Article
Full-text available
Hurricanes are infrequent but influential disruptors of ecosystem processes in the southeastern Atlantic and Gulf coasts. Every southeastern forested wetland has the potential to be struck by a tropical cyclone. We examined the impact of Hurricane Hugo on two paired coastal watersheds in South Carolina in terms of stream flow and vegetation dynamic...
Article
Full-text available
Karst watersheds possess both diffuse and conduit flow and varying degrees of connectivity between surface and groundwater over spatial scales that result in complex hydrology and contaminant transport processes. The flow regime and surface-groundwater connection must be properly identified and characterized to improve management in karst watershed...
Article
During the late 19th and early 20th centuries, a combination of weather, land use, vegetation, and complacency about forest fires amongst the public caused a series of extreme fires that resulted in the death of over 2500 people in the Great Lakes Region of the United States. Eyewitness accounts of these fires were generally stories of individual h...
Article
Epps, Thomas H., Daniel R. Hitchcock, Anand D. Jayakaran, Drake R. Loflin, Thomas M. Williams, and Devendra M. Amatya, 2012. Characterization of Storm Flow Dynamics of Headwater Streams in the South Carolina Lower Coastal Plain. Journal of the American Water Resources Association (JAWRA) 1-14. DOI: 10.1111/jawr.12000 Abstract: Hydrologic monitoring...
Article
Full-text available
The SWAT model was used to predict total phosphorus (TP) loadings for a 1,555-ha karst watershed - Chapel Branch Creek (CBC) - which drains to a lake via a reservoir-like embayment (R-E). The model was first tested for monthly streamflow predictions from tributaries draining three potential source areas as well as the downstream R-E, followed by TP...
Article
Full-text available
Southern US coastal forests are subject to damage by major Atlantic Hurricanes at a frequency that influences forest succession. Forest species may be: a) resistant: unchanged in mortality and growth; b) susceptible: increase in mortality and decrease in growth, and c) resilient: increase in mortality but increase in abundance and growth, or d) usu...
Conference Paper
Full-text available
Shallow water table soils are common in the forested watersheds of the southeastern Atlantic and Gulf coasts of the United States. The process of runoff generation is still poorly understood on these low-gradient watersheds, where soil saturation is common across the watershed. Storm runoff varies widely from none to over 70 percent of rainfall, an...
Article
Full-text available
In recent years there has been an increasing concern of water yield/balance from watersheds because of population growth, land use change, and climate change, including variability of its extremes. These concerns are equally valid for the humid Southeastern Coastal Plain as well as arid/semi-arid regions. The Coastal Plain is generally characterize...
Article
Full-text available
Forests are an integral component of the landscape, and maintaining their functional integrity is fundamental for the sustainability of ecosystems and societies alike. Tools, innovations, and practices, analogous to those developed to improve agricultural production and quantify environmental impacts, are needed to ensure the sustainability of thes...
Article
Full-text available
SWAT is a GIS-based basin-scale model widely used for the characterization of hydrology and water quality of large, complex watersheds; however, SWAT has not been fully tested in watersheds with karst geomorphology and downstream reservoir-like embayment. In this study, SWAT was applied to test its ability to predict monthly streamflow dynamics for...
Article
Full-text available
Aims In recent years, there has been an increased interest in examining changes in forest systems in response to drought, flooding, hurricanes and climate change. In the southern United States, forested wetlands are of special interest because of the extent of these forests. Coastal plain forested wetlands are among the most vulnerable to these cli...
Article
Full-text available
Digital vegetation is the computerized representation, with either virtual images or animations, of vegetation types and conditions based on current measurements or ecological models. Digital vegetation can be useful in evaluating past, present, or future land use; changes in vegetation linked to climate change; or restoration eff orts. Digital veg...
Conference Paper
Full-text available
Understanding watershed hydrology and the concentrations of nutrients in stream waters are fundamental considerations for assessing water quality loadings for a pollutant impairing the water body. In this study, supported by SC DHEC’s 319 Grant Program, hydrology and phosphorus (TP) data collected from a 1,555 ha, mixed land use, Chapel Branch Cree...
Chapter
Three-dimensional (3D) visualization is a useful tool that depicts virtual forest landscapes on computer. Previous studies in visualization have required high end computer hardware and specialized technical skills. A virtual forest landscape can be used to show different effects of disturbances and management scenarios on a computer, which allows o...
Article
Saltwater tides bring high concentrations of chloride and bromide inland where it mixes with terrestrial humic substances from surrounding forested watersheds and ferric/ferrous ions from shallow groundwater. With all the essential precursors (i.e., chloride, bromide, and humic substances) and catalysts (ferric/ferrous ions with sunlight), low-lyin...
Article
Full-text available
After a century of fire exclusion, western US forests are vulnerable to wildfire and bark beetles. Although integrated fire and pest management programs (e.g., prescribed burning and thinning) are being implemented efficiently, damage to forests continues. Management challenges come in the forms of diverse land ownership, dynamic forest landscapes,...
Conference Paper
Full-text available
SWAT, a widely used GIS-based basin scale model to characterize the hydrology and water quality for large, complex watersheds as a function of land use, soils, topography, management practices and their interactions with variability in climate, has not been fully tested on watersheds on karst topography. In this study, SWAT was used to evaluate mon...
Conference Paper
Coastal headwater streams in undeveloped forested landscapes function as a natural storage and conveyance mechanism for rainfall and groundwater. Stream flows are often driven by groundwater table depth, while soil saturation with a high water table may drive rainfall response. Evapotranspiration also plays a significant role in groundwater levels...
Chapter
Full-text available
The downstream, coastward boundary of tidal freshwater forests is easy to define. There is usually an abrupt border from forest to fresh, brackish, or salt marsh as tidal effect and salinity increase. Upstream, however, there is a continuum within the forested community as salinity and tidal signature diminish. The boundary conditions can be define...
Conference Paper
Development in coastal South Carolina, USA, is occurring at a tremendous rate. Existing developed areas contribute to a significant increase in the percentage of impervious surface area per total area of land, resulting in increased stormwater runoff and decreased infiltration. The low topographic relief and shallow water table, however, present in...
Conference Paper
The mechanisms by which forested watersheds produce rapid increase in flow following rainfall have been an area of inquiry for over 50 years. Overland flow due to rainfall rate exceeding infiltration capacity (Hortonian runoff) seldom occurs on forested watersheds. The idea of a limited source area that expands with rainfall has been widely accepte...
Article
Loblolly pine (Pinus taeda) and sweetgum (Liquidambar styraciflua) trees, growing in International Paper Company's study of intensive management on marginal agricultural land near Bainbridge GA, were destructively sampled at the end of the sixth growing season. All trees were single family blocks of genetically superior trees planted 2.5m apart on...
Article
Full-text available
Hydraulic modeling of floodplains requires accurate geographic and geometric data for both river channel and floodplain. Geographic Information Systems (GIS) allow collection and manipulation of geographic or geometric data. GIS has been integrated in several modern hydraulic modeling systems for both data input and result display. This paper will...
Conference Paper
Determination of the hydroperiod of a particular site requires a long period of water table record. On the lower coastal plain hydrology of sites is determined by subtle differences in topography and landscape position. Without vegetational clues, as after plantation establishment, estimation of site hydroperiod becomes even more problematic. Soil...
Article
Southern bottomland hardwood forests occur on river floodplains of the southeastern United States, and ecological processes are driven by seasonal floodwaters from the river. Conservation and management of southeastern US coastal plain ecosystems is a priority in South Carolina's Lowcountry Forest Conservation Project. The project is a partnership...
Chapter
Forested watersheds produce the highest quality water of any land use. High rates of infiltration prevent surface runoff in most undisturbed temperate forests, resulting in little suspended sediment or dissolved nutrients in streams of forested areas. Suspended sediment from poorly designed logging, especially improperly located or constructed haul...
Conference Paper
Voluntary Forestry Best Management Practices (BMPs) have successfully protected water quality throughout the Southeast. A variety of studies from the 1960s to 80s evaluated water quality impacts of forestry practices. They found several practices that contributed to sedimentation, the most common impairment to water quality by forestry. Forestry BM...
Article
Streamside management is an essential part of maintaining water quality during forest operations. Maintaining forest cover and forest floor near streams has been found to minimize the impact of upslope mechanical treatments. Throughout the Southeastern US streamside management is a major component in forestry practice guidelines. Width of streamsid...
Article
Cavity trees of red cockaded woodpeckers (Picoides borealis) were monitored on Hobcaw Forest prior to Hurricane Hugo and through April 1996. There were 194 cavity trees in 28 clusters on the forest prior to Hurricane Hugo and 194 in 28 clusters again in April 1996. During that period, 135 cavity trees died: 74 from hurricane wind, 25 from saltwater...
Article
Global Information Systems, including the capacity of these systems to store and manipulate data, have found great utility in analyzing spatial information. The spatial information that is most useful to watershed managers includes accounting of land-use practices that both damage and enhance water quality in watersheds. The capacity of GIS to pres...
Article
Full-text available
The land surface elevation distribution will serve as fundamental input data to any wetland flow model. As an alternative to the traditional smooth function approach to represent or interpolate elevation data, we explore the use of Levy monofractals and universal multifractals as a means for defining a statistically equivalent topography. The motiv...
Article
Loblolly pine and sweetgum were grown with irrigation, continuous fertilizer application and insect pest control on a year old abandoned peanut field. Wells and tension lysimeters were used to measure nitrate-nitrogen in soil moisture and groundwater on three replicate transects for four years. Years 1 and 2, groundwater nitrate-nitrogen concentrat...
Article
Loblolly pine (Pinus taeda L.) and sweetgum (Liquidambar styraciflua L.) were grown with irrigation, continuous fertilization, and insect pest control on a one-year-old abandoned peanut (Arachis hypogaea L.) field. Wells and tension lysimeters were used to measure nitrate in soil moisture and groundwater on three replicate transects for two years....
Article
Forest management practices in stands containing red-cockaded woodpeckers (Picoides borealis) (RCW) should follow habitat retention guidelines within designated distances of cavity trees. Geographic information systems (GIS) provide useful tools for combining map and tabular data into alternative management scenarios. However, these computerized sy...
Article
Land application of biomass fuelled boiler ash can save landfill space and return cations to the forest environment. However, environmental regulations throughout most of the U.S. do not specifically address application of biomass boiler ash to forest land. South Carolina Department of Health and Environmental Control (SCDHEC) treated bark boiler a...
Article
As part of a larger investigation of the effects of coastal urbanization on estuaries, stream nutrient loading was examined over a range of hydrologic and seasonal conditions for an urbanized and a forested watershed (11 ha versus 37 ha). Despite the smaller size, the urbanized stream produced 72% greater annual streamflow volume (162 versus 94 × 1...
Article
Three-hundred eight slug tests were conducted in a 5 × 5 m area in a coastal, sandy aquifer at the Georgetown site in South Carolina to characterize three-dimensional aquifer heterogeneity. Methods developed by Hvorslev, Bouwer and Rice, and Cooper et al. were employed to estimate hydraulic conductivity values from the slug test data. These three m...
Article
Ash from the bark-fueled power boiler at International Paper`s Georgetown mill was applied in a column study and a field trial to test land application. Tested application rates were 11, 22, and 44 Mg/ha of ash per rotation. The soil column study found a flush of cations, primarily K and Ca, with the initial 76 cm of 10⁻⁵ M oxalic acid leachate...
Article
Full-text available
Thefield-scale transport of natural organic matter (NOM) was examined in a two-well forced gradient injection experiment in a sandy, coastal plain aquifer in Georgetown, South Carolina. Spatial moments described the migration of the center of mass of NOM and conservative tracer. Temporal moments were used to estimate mass loss and retardation of th...
Article
Full-text available
A forced-gradient tracer test was conducted at the Georgetown site to study the transport of natural organic matter (NOM) in groundwater. In particular, the goal of this experiment was to investigate the interactions between NOM and the aquifer matrix. A detailed three-dimensional characterization of the hydrologic conductivity heterogeneity of the...
Article
A four hectare mixed bottomland hardwood site on Ninety Six Creek in the Piedmont of South Carolina near Ninety Six, SC was studied for two years to characterize wetland traits. The soils were thermic Fluventic or Fluvaquentic Dystrochrepts predominantly Shellbluff series and well drained. Overbank flooding occurred on the average of 4 times per ye...
Article
Despite its intensity and landfall at high tide, Hurricane Hugo (22 Sept. 1989) had only a modest impact on the geomorphology of the undeveloped coastal landscape at North Inlet, South Carolina. Pre- and post-Hugo aerial photographs (April 1987 and October 1989) showed no change in the salt-marsh creek network, nor could changes be seen in the size...
Article
Dissolved and particulate organic carbon fluxes were measured within the Bly Creek basin, North Inlet area, Georgetown County, South Carolina. 34 tidal cycles were sampled between 20 June 1986 and 19 June 1984. Flux direction and magnitude were determined for each measured tidal cycle. Continuously measured auxiliary variables were used in a regres...