Simulation of groundwater flow and saltwater movement in the Onslow County area, North Carolina: predevelopment-2010

Jason M. Fine; Eve L. Kuniansky

doi:10.3133/sir20135236

Home/Archive/USGS

USGS · sir20135236

Simulation of groundwater flow and saltwater movement in the Onslow County area, North Carolina: predevelopment-2010

Jason M. Fine·Eve L. Kuniansky

View original source ↗Read source document ↗Export metadata ↓

Abstract

Onslow County, North Carolina, is located within the designated Central Coastal Plain Capacity Use Area (CCPCUA). The CCPCUA was designated by law as a result of groundwater level declines of as much as 200 feet during the past four decades within aquifers in rocks of Cretaceous age in the central Coastal Plain of North Carolina and a depletion of water in storage from increased groundwater withdrawals in the area. The declines and depletion of water in storage within the Cretaceous aquifers increase the potential for saltwater migration—both lateral encroachment and upward leakage of brackish water. Within the CCPCUA, a reduction in groundwater withdrawals over a period of 16 years from 2003 to 2018 is mandated. Under the CCPCUA rules, withdrawals in excess of 100,000 gallons per day from any of the Cretaceous aquifer well systems are subject to water-use reductions of as much as 75 percent. To assess the effects of the CCPCUA rules and to assist with groundwater-management decisions, a numerical model was developed to simulate the groundwater flow and chloride concentrations in the surficial Castle Hayne, Beaufort, Peedee, and Black Creek aquifers in the Onslow County area. The model was used to (1) simulate groundwater flow from 1900 to 2010; (2) assess chloride movement throughout the aquifer system; and (3) create hypothetical scenarios of future groundwater development. After calibration of a groundwater flow model and conversion to a variable-density model, five scenarios were created to simulate future groundwater conditions in the Onslow County area: (1) full implementation of the CCPCUA rules with three phases of withdrawal reductions simulated through 2028; (2) implementation of only phase 1 withdrawal reductions of the CCPCUA rules and simulated through 2028; (3) implementation of only phases 1 and 2 withdrawal reductions of the CCPCUA rules and simulated through 2028; (4) full implementation of the CCPCUA rules with the addition of withdrawals from the Castle Hayne aquifer in Onslow County at the fully permitted amount in the final stress period and simulated through 2028; and (5) full implementation of the CCPCUA rules as in scenario 1 except simulated through 2100. Results from the scenarios give an indication of the water-level recovery in the Black Creek aquifer throughout each phase of the CCPCUA rules in Onslow County. Furthermore, as development of the Castle Hayne aquifers was increased in the scenarios, cones of depression were created around pumping centers. Additionally, the scenarios indicated little to no change in chloride concentrations for the time periods simulated.

Explore related subjects

Scientific Investigations Report Report

Source-reported bounding extent: 34.1967° to 35.4025° latitude; -78.0011° to -76.892° longitude. This indicates report coverage, not an exact sampling location. View area on OpenStreetMap.

Keep this discovery

Explore connections, maps & timelines

BibTeX RIS

Jason M. Fine, Eve L. Kuniansky. 2014. Simulation of groundwater flow and saltwater movement in the Onslow County area, North Carolina: predevelopment-2010. https://doi.org/10.3133/sir20135236

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related USGS reports

USGS2026

Monitoring recreation on federally managed lands and waters—Aspects of visitor use

Federally managed public lands and waters receive around 1 billion recreational visits each year. Data on these visitors can aid in guiding policy decisions, managing resources effectively, and communicating the economic contributions of lands and waters. This report explores the methods used by agencies to collect data on aspects of recreational visitor use to Federal lands and waters (apart from visitation numbers, which are the focus of a companion publication). Aspects of recreational visitor use include visitor demographics, recreational activity participation, visitor satisfaction, visitor attitudes and experiences, trip characteristics, and economic contributions. We review practices used to understand aspects of visitor use across seven Federal agencies, revealing similarities such as the use of visitor intercept surveys and coverage of similar topic areas, and differences in how survey programs are operationalized and how specific questions on visitor surveys are worded. We also evaluate emerging technologies, such as geolocated social media and mobile device location data, for their potential to aid in understanding aspects of visitor use. This report concludes with potential opportunities to enhance data collection and coordination, ensuring cost-effective data collection and informed decision making.

Scientific Investigations Report↗

USGS2026

Evaluation of best management practices at an edge-of-field site in the Eagle Creek watershed, Ohio, 2012–20

In 2010, the U.S. Geological Survey worked in partnership with the Great Lakes Restoration Initiative and the Natural Resources Conservation Service to identify farm fields in priority watersheds—watersheds critically important to Great Lake health. Intensive best management practices were implemented in five States to test the efficacy of best management practices, also referred to as agricultural conservation practices, to reduce sediment and nutrient runoff on agricultural fields. These fields were chosen as representatives of the priority watersheds because their farming practices and geographical conditions were common among farms in those watersheds. A farm site located near Findlay, Ohio, in the Eagle Creek watershed used two conservation practices, cover crop (Natural Resources Conservation Service practice standard 340) and variable rate technology (VRT; Natural Resources Conservation Service practice standard 590), which represent common practices in the Maumee priority watershed. This study monitored surface runoff and subsurface tile runoff at the Eagle Creek watershed site. The effects of cover crop and VRT nutrient application on sediment and nutrient runoff were assessed from October 2012 to September 2020. Cover crops were applied in fall of 2016, 2017, and 2018, coinciding with VRT applications. The following parameters were analyzed as part of the study: runoff discharge; peak discharge; and concentrations and loads of total phosphorus, particulate phosphorus, dissolved reactive phosphorus, and suspended sediment. High peak runoff events disproportionally affected nutrient concentrations and loads in runoff. A threshold of the 85th percentile of the peak discharge was chosen to assess the effect of cover crop and VRT nutrient application on nutrient mitigation at each gage. Runoff events below the 85th percentile were considered small, and runoff events over the 85th percentile were considered large. Concentrations from collected water-quality samples were used for the analysis; estimated concentrations were excluded from the statistical evaluation. All surface runoff parameters during small runoff events, except surface runoff volume, were significantly lower in the period with cover crops and VRT implementation. Contrarily, subsurface runoff parameters during small events were not statistically different between the periods with and without cover crops and VRT implementation. Surface and subsurface parameters during large events were also not statistically different between the periods with and without cover crops and VRT implementation. These results indicate cover crops and VRT may improve water quality during small runoff events, but additional best management practices that mitigate large runoff events may lead to greater water-quality improvement given the contribution of large events to overall losses.

Ohio↗

USGS2026

Continuous monitoring and temporal variability of fluorescence of dissolved organic matter in karst groundwater of the Edwards aquifer, south-central Texas, 2019–24

Widespread urbanization on the Edwards aquifer recharge zone in south-central Texas has prompted the development of new approaches and tools for evaluating the current and future status of water quality in the San Antonio and Barton Springs segments of the Edwards aquifer. The U.S. Geological Survey, in cooperation with the San Antonio Water System and the City of Austin, applied continuous monitoring of fluorescence of dissolved organic matter (fDOM) to characterize the sources and transport of dissolved organic matter and associated constituents in the Edwards aquifer. Continuous fDOM time-series data were adjusted using empirically derived temperature, turbidity, and inner-filter-effect correction factors prior to analysis and interpretation. Fully corrected fDOM time-series data from the study sites were evaluated for short- and long-term temporal variability in fDOM in the context of the hydrologic and climatic conditions that occurred during the 5-year study period to understand vulnerability of the aquifer to potential contaminants in recharge. Study results indicate that fDOM is an effective proxy for dissolved organic carbon that, in turn, is indicative of the influx of recent surface water and associated contaminants, and thus, aquifer vulnerability to those contaminants. Although other continuously monitored water-quality parameters provide insights into changes in water quality in response to varying hydrologic conditions, the quantitative relation between fDOM and dissolved organic carbon directly indicates the timing and magnitude of pulses of organic constituents derived from the land surface, whereas other water-quality parameters do not.

Texas↗