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United States Department of Agriculture

Agricultural Research Service

Research Project: Advancement of Erosion Modeling and Precision Conservation Planning to Target Ephemeral Gully Control in the Lower South Fork Watershed

Location: Watershed Physical Processes Research Unit

Project Number: 6408-13000-023-34
Project Type: Reimbursable

Start Date: Oct 01, 2012
End Date: Aug 31, 2015

Objective:
(1) Make use of available Light Detection and Ranging (LiDAR) data, rainfall data, and historical and on-going measurements of sediment yield from 24 field-scale watersheds in central Iowa to validate predictions of a recently developed, field-scale, distributed erosion and ephemeral gully calculator. (2) Compare predicted ephemeral gully channel locations and properties with ground-truth observations obtained using survey and photogrammetric techniques.

Approach:
1) Analyze historic and contemporary rainfall and runoff data available from the South Fork Watershed (2 sites, 12 years to date), the South Walnut Creek Watershed (12 sites, 6 years), and Clear Creek Watershed (10 sites, 3 years). Compare observed monthly rainfall and rainfall intensity values to the long-term county-level averages that serve as RUSLE2 climatic inputs. Compare the observed runoff event population to the statistical distribution of runoff events predicted by RUSLE2 for each sub-watershed. 2) Apply beta version of the distributed erosion and ephemeral gully calculator to model the above 24 research-scale basins and compare predictions of sediment yield, gully location, and gully channel dimensions to measurements collected by cooperators. 3) Validate the channel locations predicted from existing Light Detection and Ranging (LiDAR) data by comparison with field observations of gullies mapped by cooperators using a global positioning system (GPS). 4) Validate the new ephemeral gully model by comparing predicted channel cross sections with measurements collected by cooperators using stereo photogrammetry and real-time kinematic GPS techniques following gully-forming runoff events.

Last Modified: 7/22/2014
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