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ARS Home » Plains Area » Temple, Texas » Grassland Soil and Water Research Laboratory » Research » Publications at this Location » Publication #317810
Title: Delineating floodplain and upload areas for hydrologic models: A comparison of methods

Author
item RATHJENS, H - Purdue University
item BIEGER, K - Texas A&M Agrilife
item CHAUBEY, I - Purdue University
item Arnold, Jeffrey
item ALLEN, P - Baylor University
item SRINIVASAN, R - Texas A&M University
item Bosch, David - Dave
item VOLK, M - Helmholtz Centre

Submitted to: Hydrological Processes
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/10/2016
Publication Date: 8/2/2016
Citation: Rathjens, H., Bieger, K., Chaubey, I., Arnold, J.G., Allen, P.M., Srinivasan, R., Bosch, D.D., Volk, M. 2016. Delineating floodplain and upload areas for hydrologic models: A comparison of methods. Hydrological Processes. 30:4367-4383. doi:10.1002/hyp.10918.

Interpretive Summary: In previous USDA national conservation assessments, the location of agriculture on the landscape was not considered. In this study, four methods using topography and delineating landscape units within a watershed were tested and compared to FEMA flood maps and to USDA soil flood frequency maps. The methods were tested on three watersheds in different ecoregions located in Texas, Indiana and Georgia. Results showed that two of the methods worked well in all three watersheds. These methods allow us to delineate flood plains and riparian zones from upland landscape units, thus providing the ability to model the impact of landscape position in managing pollutant runoff. It will also improve USDA national conservation assessments by allowing explicit simulation of riparian and flood plain sediment deposition and nutrient removal.

Technical Abstract: A spatially distributed representation of basin hydrology and transport processes in eco-hydrological models facilitates the identification of critical source areas and the placement of management and conservation measures. Floodplains are critical landscape features that differ from neighboring uplands in terms of their eco-hydrologic processes and functions. Accordingly, an important step in watershed modeling is the representation of floodplain and upland areas within a watershed. However, currently no geo-computational framework for landscape unit delineation exists that meets the needs of subwatershed-based hydrologic models. The aim of this study is to (1) evaluate four floodplain-upland delineation methods (topographic wetness index, slope position, uniform flood stage, and variable flood stage) with regard to their suitability for hydrologic models and (2) present a geocomputational framework for delineating floodplain and upland landscape units in a watershed using readily available topographic data; and (3) to introduce an evaluation scheme for the delineated landscape units. The methods are tested in three U.S. watersheds with different climatic, hydrological and geomorphological characteristics. Evaluation of the landscape delineation methods is based on visual comparisons and error matrices (i.e. cross-tabulations of delineated versus reference data). Reference data was obtained from SSURGO flood frequency maps and FEMA flood maps. Results suggest that the slope position and the variable flood stage method work very well in all three watersheds. Overall accuracy values (i.e. overall percentage of areas allocated correctly) range from 83 to 93 % for the slope position and from 80 to 95 % for the variable flood stage method. Future studies will incorporate the floodplain-upland discretization framework into subwatershed-based eco-hydrological models to ensure a realistic representation of hydrologic processes within floodplain and upland areas.