|SHIELDS, FLETCHER - Retired ARS Employee|
Submitted to: Ecological Engineering
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/3/2012
Publication Date: 4/5/2013
Citation: Shields, F.D., Knight, S.S. 2013. Floodplain restoration with flood control: fish habitat value of levee borrow pits. Ecological Engineering. 53:217-227 doi:10.1016/jecoleng.2012.12.046.
Interpretive Summary: To protect crops from flooding, earthen flood control levees are often constructed along streams in floodplain landscapes such as the Mississippi Delta, isolating natural areas from periodic flooding on which they depend. Lost ecosystem services due to levee construction may be partially recovered by using floodplain soils excavated from pits on the waterside of the levee so that the pits provide floodplain lake habitats after levee construction. The value of such borrow pits along large rivers is well established, but little information is available regarding borrow pits along smaller streams. Six borrow pits along Abiaca Creek in north central Mississippi were studied for two years. Sport fish populations were of highest quality in the larger pits with sinuous shorelines, periodic hydrologic connection to the stream, and greatest water clarity. These findings may be used to design and manage flood control levee projects.
Technical Abstract: Earthen flood control levees are often built using soil excavated from borrow pits lying parallel to and riverward of the finished levee. After construction, these pits can provide valuable floodplain habitats, and their value is well established along corridors of larger rivers. However, levee borrow pits along smaller streams have not been studied. Six waterside levee borrow pits were studied for about two years along Abiaca Creek, which drains a 202 km2 watershed in central Mississippi. Fish were sampled annually from six pits using boat-mounted electrofishing, and water quality samples were collected weekly from four pits. Continuous records of stream and borrow pit water levels were coupled with topographic and bathymetric survey data of the floodway to compute the frequency of connection between each pit and temporal distributions of aquatic habitat characteristics. Pit water surface areas ranged from 0.4 to 11.7 ha, and mean depth ranged from 0.5 to 1.8 m. Pits were hydraulically connected to the stream 1% to 34% of the time. Dissolved oxygen concentrations ranged from 0.30 to 13.7 mg L-1 and were inversely related to water depth. Fish collections yielded 1,768 individuals representing 26 species. Larger-bodied fishes and some piscivores were more common in larger, more elongated pits with more sinuous shorelines. Features of pits with the highest biotic indices may be used to guide design and management of future floodplain restoration projects.