Geology topics

Tanja N. Williamson

Publications and source records attributed to Tanja N. Williamson.

41 records · Page 3Linked to original sources

USGS2012

Phase II modification of the W ater A vailability T ool for E nvironmental R esources (WATER) for Kentucky: The sinkhole-drainage process, point-and-click basin delineation, and results of karst test-basin simulations

This report describes Phase II modifications made to the Water Availability Tool for Environmental Resources (WATER), which applies the process-based TOPMODEL approach to simulate or predict stream discharge in surface basins in the Commonwealth of Kentucky. The previous (Phase I) version of WATER did not provide a means of identifying sinkhole catchments or accounting for the effects of karst (internal) drainage in a TOPMODEL-simulated basin. In the Phase II version of WATER, sinkhole catchments are automatically identified and delineated as internally drained subbasins, and a modified TOPMODEL approach (called the sinkhole drainage process, or SDP-TOPMODEL) is applied that calculates mean daily discharges for the basin based on summed area-weighted contributions from sinkhole drain-age (SD) areas and non-karstic topographically drained (TD) areas. Results obtained using the SDP-TOPMODEL approach were evaluated for 12 karst test basins located in each of the major karst terrains in Kentucky. Visual comparison of simulated hydrographs and flow-duration curves, along with statistical measures applied to the simulated discharge data (bias, correlation, root mean square error, and Nash-Sutcliffe efficiency coefficients), indicate that the SDPOPMODEL approach provides acceptably accurate estimates of discharge for most flow conditions and typically provides more accurate simulation of stream discharge in karstic basins compared to the standard TOPMODEL approach. Additional programming modifications made to the Phase II version of WATER included implementation of a point-and-click graphical user interface (GUI), which fully automates the delineation of simulation-basin boundaries and improves the speed of input-data processing. The Phase II version of WATER enables the user to select a pour point anywhere on a stream reach of interest, and the program will automatically delineate all upstream areas that contribute drainage to that point. This capability enables automatic delineation of a simulation basin of any size (area) and having any level of stream-network complexity. WATER then automatically identifies the presence of sinkholes catchments within the simulation basin boundaries; extracts and compiles the necessary climatic, topographic, and basin characteristics datasets; and runs the SDP-TOPMODEL approach to estimate daily mean discharges (streamflow).

Kentucky↗

USGS2012

Construction of estimated flow- and load-duration curves for Kentucky using the W ater A vailability T ool for E nvironmental R esources (WATER)

Flow- and load-duration curves were constructed from the model outputs of the U.S. Geological Survey's Water Availability Tool for Environmental Resources (WATER) application for streams in Kentucky. The WATER application was designed to access multiple geospatial datasets to generate more than 60 years of statistically based streamflow data for Kentucky. The WATER application enables a user to graphically select a site on a stream and generate an estimated hydrograph and flow-duration curve for the watershed upstream of that point. The flow-duration curves are constructed by calculating the exceedance probability of the modeled daily streamflows. User-defined water-quality criteria and (or) sampling results can be loaded into the WATER application to construct load-duration curves that are based on the modeled streamflow results. Estimates of flow and streamflow statistics were derived from TOPographically Based Hydrological MODEL (TOPMODEL) simulations in the WATER application. A modified TOPMODEL code, SDP-TOPMODEL (Sinkhole Drainage Process-TOPMODEL) was used to simulate daily mean discharges over the period of record for 5 karst and 5 non-karst watersheds in Kentucky in order to verify the calibrated model. A statistical evaluation of the model's verification simulations show that calibration criteria, established by previous WATER application reports, were met thus insuring the model's ability to provide acceptably accurate estimates of discharge at gaged and ungaged sites throughout Kentucky. Flow-duration curves are constructed in the WATER application by calculating the exceedence probability of the modeled daily flow values. The flow-duration intervals are expressed as a percentage, with zero corresponding to the highest stream discharge in the streamflow record. Load-duration curves are constructed by applying the loading equation (Load = Flow*Water-quality criterion) at each flow interval.

Kentucky↗

USGS2011

Estimation of suspended-sediment concentration from total suspended solids and turbidity data for Kentucky, 1978-1995

Suspended sediment is a constituent of water quality that is monitored because of concerns about accelerated erosion, nonpoint contamination of water resources, and degradation of aquatic environments. In order to quantify the relationship among different sediment parameters for Kentucky streams, long‐term records were obtained from the National Water Information System of the U.S. Geological Survey. Suspended‐sediment concentration (SSC), the parameter traditionally measured and reported by the U.S. Geological Survey, was statistically compared to turbidity and total suspended solids (TSS), two parameters that are considered surrogate data. A linear regression of log‐transformed observations was used to estimate SSC from TSS; 72% of TSS observations were less than coincident SSC observations; however, the estimated SSC values were almost as likely to be overestimated as underestimated. The SSC‐turbidity relationship also used log‐transformed observations, but required a nonlinear, breakpoint regression that separated turbidity observations ≤6 nephelometric turbidity units. The slope for these low turbidity values was not significantly different than zero, indicating that low turbidity observations provide no real information about SSC; in the case of the Kentucky sediment record, this accounts for 30% of the turbidity observations.

Kentucky↗

USGS2009

Inventory and Statistical Analysis of Sediment Data for Streams in Kentucky, 1950-2008

Suspended sediment is a constituent of water that is monitored because of concerns about accelerated erosion, nonpoint contamination of water resources, and degradation of aquatic environments. Understanding the availability of monitored sediment data for streams in Kentucky is critical to planning future modeling and monitoring efforts. In order to assess the availability of sediment data for Kentucky, long-term records were obtained from the National Water Information System (NWIS) of the U.S. Geological Survey (USGS). Suspended-sediment concentration (SSC), the parameter traditionally measured and reported by the USGS, was statistically compared to turbidity and total suspended solids (TSS), two parameters that are considered surrogate data. Coincident observations of SSC with either turbidity or TSS were available for 42 sites. In combination with instantaneous streamflow, turbidity and TSS both proved to be significant indicators of SSC when data from all sites were used. Because of the perceived link between sediment and nutrient abundance in streams, sediment-parameter data at these sites were correlated to total-nitrogen and total-phosphorus concentrations. A significant relation (p-value < 0.05) was found between monitored nutrient concentrations and coincident sediment abundance, although there were no clear linear relations. This compilation of data showed that SSC was monitored at 118 sites in Kentucky at some time between 1950 and 2008. As of March 2008, 9 sites were monitored for SSC in Kentucky (8 of which are new) down from a high of more than 60 SSC sites during the 1980s. Of these 118 SSC sites, 21 sites were also monitored for TSS; there are coincident records for both SSC and TSS at 6 sites. Forty-seven of these long-term water-quality sites were also monitored for turbidity; there are coincident records for SSC and turbidity at 42 sites, including all of those at which there are coincident data for TSS. The number of sites at which SSC and at least one other sediment parameter (TSS or turbidity) were monitored decreased from a high of 27 in 1987 to zero during the period 2001-2005.

Scientific Investigations Report↗

USGS2009

The Water Availability Tool for Environmental Resources (WATER): A water-budget modeling approach for managing water-supply resources in non-karst areas of Kentucky (phase I) — Data processing and model structure documentstion

The Water Availability Tool for Environmental Resources (WATER) was developed in cooperation with the Kentucky Division of Water to provide a consistent and defensible method of estimating streamflow and water availability in ungaged basins. WATER is process oriented; it is based on the TOPMODEL code and incorporates historical water-use data together with physiographic data that quantitatively describe topography and soil-water storage. The result is a user-friendly decision tool that can estimate water availability in non-karst areas of Kentucky without additional data or processing. The model runs on a daily time step, and critical source data include a historical record of daily temperature and precipitation, digital elevation models (DEMs), the Soil Survey Geographic Database (SSURGO), and historical records of water discharges and withdrawals. The model was calibrated and statistically evaluated for 12 basins by comparing the estimated discharge to that observed at U.S. Geological Survey streamflow-gaging stations. When statistically evaluated over a 2,119-day time period, the discharge estimates showed a bias of -0.29 to 0.42, a root mean square error of 1.66 to 5.06, a correlation of 0.54 to 0.85, and a Nash-Sutcliffe Efficiency of 0.26 to 0.72. The parameter and input modifications that most significantly improved the accuracy and precision of streamflow-discharge estimates were the addition of Next Generation radar (NEXRAD) precipitation data, a rooting depth of 30 centimeters, and a TOPMODEL scaling parameter (m) derived directly from SSURGO data that was multiplied by an adjustment factor of 0.10. No site-specific optimization was used.

Kentucky↗