Increased water yields following harvesting operations on a drained coastal watershed
Forest harvesting operations have been reported to affect annual and seasonal outflow characteristics from drained forest watersheds. Increases in forest outflow, nutrient concentrations, and suspended sediments are commonly seen as a result of these forest management activities. Thus, it is important to assess the impact of forest management activities on hydrology, soils, and water quality on drained forested lands. The impact of harvesting a 23-ha mature natural (primarily hardwood) forest stand located in Washington County near Plymouth, North Carolina was evaluated using a paired watershed approach. Event outflow, event peak flow, and number of flow days were significantly increased by the harvesting operation. Mean event outflow increased from 22.6 mm on the control to 47.3 mm on the harvested, which represents a 2-fold increase. Similarly, event peak flow and number of flow days from the harvested watershed were more than 50 percent greater than observed on the control. Daily outflow and water table depths observed on the harvested watershed were similar to those from the control. Mean water table depths for the harvested and control were 68 and 97 cm during the treatment period.