Researchers study erosion control costs, benefits

Urban construction projects have intensified erosion and sedimentation in North Carolina, even though the state has one of the nation’s strongest erosion control programs. To solve the problem, Gov. James Hunt has called on the state Department of Environment and Natural Resources to step up enforcement of regulations, assess regulatory inadequacies and recommend changes to the General Assembly.

The state also has enlisted the assistance of researchers at North Carolina State University in Raleigh. The researchers will assess the economic damage from sedimentation as well as the benefits derived from erosion control. According to Diane Cherry, who heads a research team from the university’s Department of Agriculture and Resource Economics, the study seeks to: * provide a framework for estimating the relationship between erosion and sedimentation control at urban construction sites; * describe the state of science and the challenges confronting researchers as they estimate these linkages; * describe economic methodologies and studies that have been used to estimate soil erosion’s impact on human activities; and * identify a research agenda for a statewide assessment of soil erosion’s impacts where there are gaps in the science.

According to Cherry, increased erosion and sedimentation have two types of impacts: in-stream impacts, when the sediment particles settle or are suspended in the water; and off-stream impacts, which occur after the particles leave the water. The loss of soil as well as implementation costs for erosion prevention and sediment entrapment are the major construction-site costs of sedimentation.

Off-site, erosion and sedimentation cause both physical and biological changes in water quality, Cherry says. For example, dissolved oxygen, temperature, turbidity, pH levels, odor, nutrient and chemical concentrations can be affected physically. Biological effects are felt by fish populations and algae, and in bacterial and microbial levels.

A decline in fishing and water recreation, decreased property values for lakefront homes, increased treatment needs for water and the use of alternative water supplies are among the economic impacts the research team will examine. Cherry says her team expects to complete the study this spring.

-Peggy Caylor