Case Study Hydrologic Effects of Size and Location of Fields Converted from Drained Pine Forest to Agricultural Cropland

Abstract: Hydrological effects of land-use change are of great concern to ecohydrologists and watershed managers, especially in the Atlantic coastal plain of the southeastern United States. The concern is attributable to rapid population growth and the resulting pressure to develop forested lands. Many researchers have studied these effects in various scales, with varying results. An extended watershed-scale forest hydrologic model, calibrated with 1996–2000 data, was used to evaluate long-term hydrologic effects of conversion to agriculture (corn–wheat–soybean cropland) of a 29.5-km2 intensively managed pine-forested watershed in Washington County in eastern North Carolina. Fifty years of weather data (1951–2000) from a nearby weather station were used for simulating hydrology to evaluate effects on outflows, evapotranspiration, and water table depth compared with the baseline scenario. Other simulation scenarios were created for each of five different percentages (10, 25, 50, 75, and 100%) of land-use conversion occurring at upstream and downstream locations in the pine-forest watershed. Simulations revealed that increased mean annual outflow was significant (α 0.05) only for 100 % conversion from forest (261 mm) to agricultural crop (326 mm), primarily attributed to a reduction in evapotranspiration. Although high flow rates>5 mm day−1 increased from 2.3 to 2.6 % (downstream) and 2.6 to 4.2 % (upstream) for 25 to 50 % conversion, the frequency was higher for the upstream location than the downstream. These results were attributed to a substantial decrease in soil hydraulic conductivity of one of the dominant soils in the upstream location, which is expected after land-use conversion to agriculture. As a result, predicted subsurface drainage decreased, and surface runoff increased as soil hydraulic conductivity decreased for the soil upstream. These results indicate tha

Long-Term Ecohydrologic Monitoring: A Case Study from the Santee Experimental Forest, South Carolina

Long-term research on gauged watersheds within the USDA Forest Service’s Experimental Forest and Range (EFR) network has contributed substantially to our understanding of relationships among forests, water, and hydrologic processes and watershed management, yet there is only limited information from coastal forests. This article summarizes key findings from hydrology and water-quality studies based on long-term monitoring on first-, second-, and third-order watersheds on the Santee Experimental Forest, which are a part of the headwaters of the east branch of the Cooper River that drains into the harbor of Charleston, South Carolina. The watersheds are representative forest ecosystems that are characteristic of the low-gradient Atlantic Coastal Plain. The long-term (35-year) water balance shows an average annual runoff of 22% of the precipitation and an estimated 75% for the evapotranspiration (ET), leaving the balance to groundwater. Non-growing season prescribed fire, an operational management practice, shows no effects on streamflow and nutrient export. The long-term records were fundamental to understanding the effects of Hurricane Hugo in 1989 on the water balance of the paired watersheds that were related to vegetation damage by Hugo and post-Hugo responses of vegetation. The long-term precipitation records showed that the frequency of large rainfall events has increased over the last two decades. Although there was an increase in air temperature, there was no effect of that increase on annual streamflow and water table depths. The long-term watershed records provide information needed to improve design, planning, and assessment methods and tools used for addressing the potential impacts of hydrologic responses on extreme events; risk and vulnerability assessments of land use; and climate and forest disturbance on hydrology, ecology, biogeochemistry, and water supply

Downward Longwave Radiation Retrieved from MODIS Imagery and Possible Application on Water Resource Management at Turkey Creek Watershed in South Carolina

2010 S.C. Water Resources Conferences - Science and Policy Challenges for a Sustainable Futur

Downward Longwave Radiation Retrieved from MODIS Imagery and Possible Application on Water Resource Management at Turkey Creek Watershed in South Carolina

2010 S.C. Water Resources Conferences - Science and Policy Challenges for a Sustainable Futur

Comparison of Potential Evapotranspiration (PET) using Three Methods for a Grass Reference and a Natural Forest in Coastal Plain of South Carolina

2014 S.C. Water Resources Conference - Informing Strategic Water Planning to Address Natural Resource, Community and Economic Challenge

Storm Event Analysis at Nested Watershed Scales: Turkey Creek, Santee Experimental Forest, South Carolina

Coastal areas are expected to see the greatest impact on water resources due to population increase and land development affecting the regional water budget by reducing evapotranspiration, groundwater recharge/discharge, and increase runoff. This project inspected forested watersheds in coastal South Carolina to understand their stream response to storm events. The objectives of this study were to (1) characterize the watershed conditions based on their land use/land cover, soil drainage class, and topography, (2) compare streamflow patterns using seasonal event hydrographs, and (3) compare results of analytical method of storm event hydrograph separation with that of the chemical method using stable water isotopes. Turkey Creek, a third-order watershed (5,240 ha), includes two first-order sub-watersheds. Physical and chemical hydrograph separation techniques and statistical methods were used for storm event analysis. Average annual rainfall for the study period was 1449 mm. The largest mean ROC, DROC, direct runoff to streamflow ratio, and peak flow rate were observed for the smallest sub-watershed (Conifer) and the lowest for the largest watershed (WS78). The largest baseflow to streamflow ratio was observed in WS78. Stable water isotope results show surface water samples isotopically distinct compared to groundwater and rainfall samples. Isotope results indicated baseflow contribution was 58-65% of streamflow in contrast to 35-41% as estimated from the hydrograph separation method. Interpretations of the results suggest that storm response was dependent on the antecedent conditions and soil type in the watershed. Scientists and land managers can use this data to predict runoff changes in areas affected by land development

Modeling the Effect of Land Use Change on Hydrology of a Forested Watershed in Coastal South Carolina

2008 S.C. Water Resources Conference - Addressing Water Challenges Facing the State and Regio

Modeling the Effect of Land Use Change on Hydrology of a Forested Watershed in Coastal South Carolina

2008 S.C. Water Resources Conference - Addressing Water Challenges Facing the State and Regio

Hydrologic Processes of Forested Headwater Watersheds Across a Physiographic Gradient in the Southeastern United States

2008 S.C. Water Resources Conference - Addressing Water Challenges Facing the State and Regio

Hydrologic Processes of Forested Headwater Watersheds Across a Physiographic Gradient in the Southeastern United States

2008 S.C. Water Resources Conference - Addressing Water Challenges Facing the State and Regio