Faculty Publications

Sediment Storage and Drainage Ditch Excavation on the North Carolina Coastal Plain: A Case Study in Pitt County

Document Type

Article

Journal/Book/Conference Title

North Carolina Geographer

Volume

8

First Page

55

Last Page

63

Abstract

The storage component of a fluvial sediment budget is difficult to quantify, yet is critical to understanding the fate of soils eroded from agricultural lands. The drainage systems in eastern North Carolina are heavily modified by human activity and are presently dominated by maintained ditches. The periodic re-excavation of the drainage ditches provides a unique opportunity to investigate the accretion of stored alluvial sediments. This paper presents an initial evaluation of the effects of channel excavation with particular focus on adjustments in channel morphology and sediment characteristics. Sixteen cross-sectional profiles were monitored along a 40m ditch segment over a one year period following re-excavation. The depth and composition of stored bed sediments were measured. Ditch excavation produced a sediment sink that resulted in a significant positive net change in alluvial storage and relatively simple cross-sectional morphology. The stored sediments lacked a fine fraction, suggesting that fines are transported beyond the study reach. Beginning in spring, vegetation growth increased the hydraulic roughness within the ditches and resulted in a decrease in sediment transport and an increase in complexity of cross-sectional channel morphology. We tentatively conclude that sediment eroded from coastal plain agricultural land does not travel very far from its source.

Department

Department of Geography

Original Publication Date

6-6-2000

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