Little River Experimental Watershed, a keystone in understanding of coastal plain watersheds

Authors: Bosch, David - Dave; Coffin, Alisa; SHERIDAN, JOSEPH; Pisani, Oliva; ENDALE, DINKU; Strickland, Timothy - Tim

Submitted to: Hydrological Processes
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/1/2021
Publication Date: 8/4/2021
Citation: Bosch, D.D., Coffin, A.W., Sheridan, J.M., Pisani, O., Endale, D.M., Strickland, T.C. 2021. Little River Experimental Watershed, a keystone in understanding of coastal plain watersheds. Hydrological Processes. 35, e14334. https://doi.org/10.1002/hyp.14334.
DOI: https://doi.org/10.1002/hyp.14334

Interpretive Summary: Long-term hydrologic and water quality data from watersheds are a key component to building an understanding that will dictate what and where changes in watershed management need to be made to achieve improvements in ecosystem services. The US Department of Agriculture Agricultural Research Service Southeast Watershed Research Laboratory (SEWRL) initiated a hydrologic research program on the Little River Experimental Watershed (LREW) in 1967. Long-term (up to 52 years) of research quality streamflow data are currently available for nine flow measurement sites within the US EPA Level III Southeastern Plains ecoregion. Climatic and streamflow data from the studied watersheds were used to make comparisons across multiple scales in the region. The comparisons indicated few differences. Differences found for a smaller nested watershed indicate significant changes in crop and forest coverage can alter long-term hydrologic characteristics. This study increases the scientific confidence of using these data for additional regional watersheds. Continued operation of the LREW network supports hydrologic research as well as environmental quality and riparian research programs.

Technical Abstract: The US Department of Agriculture-Agricultural Research Service Southeast Watershed Research Laboratory (SEWRL) initiated a hydrologic research program on the Little River Experimental Watershed (LREW) in 1967. Long-term (52 years) of streamflow data are available for nine sites, including rainfall-runoff relationships and hydrograph characteristics regularly used in research on interactive effects of climate, vegetation, soils, and land-use in low-gradient streams of the US EPA Level III Southeastern Plains ecoregion. Climatic and streamflow data were used to make comparisons of scale across the nine nested LREW watersheds and two regional watersheds, the Alapaha and Little River at Adel. Annual rainfall for the largest LREW, LRB, was 1200 mm while average annual streamflow was 320 mm. Annual rainfall, streamflow, and the ratio between annual streamflow and rainfall (Sratio) were similar (a=0.05) across LREWs LRB, LRF, LRI, LRJ, LRK, and LRO. While annual rainfall within the 275 ha LRO3 was found similar to LRO and LRM (a=0.05), annual streamflow and Sratio were significantly different (a=0.05). Comparisons of annual rainfall, streamflow, and Sratio between LRB and the regional watersheds indicated no differences (a=0.05). Based upon this analysis, most regional watersheds shared similar hydrologic characteristics. LRO3 was an exception, where increases in row crops and decreases in forest coverage resulted in increased streamflow. These differences do not carry over to LRO, into which LRO3 drains, likely because LRO has land features more typical of the region, implying there is a level of scale at which significant changes in crop and forest coverage can alter streamflow characteristics. The LREW data have been instrumental in building considerable scientific understanding of flow and transport processes for these stream systems. Continued operation of the LREW hydrologic network will support hydrologic research as well as environmental quality and riparian research programs that address emerging and high priority areas.