ABSTRACT:

Stream flowline delineation from high-resolution digital elevation models (HRDEMs) can be biased partly due to the as absence of information on the locations of anthropogenic drainage structures (ADS) such as bridges and culverts on the grid surface. Without the ADS, the roads may act as ‘digital dams’ that prevent the overland drainages correctly crossing through in the flowline delineation. However, it is unclear if a combination of variables for terrain-based hydrologic modeling can be used to mitigate the effect of ‘digital dams.’ This study assessed the impacts of ADS locations, spatial resolution (ranging from 1-m to 10-m), depression processing methods (filling, breaching, and stream burning), and flow direction algorithms (D8, D-Infinity, and MFD-md) on hydrologic connectivity through ADS in an agrarian landscape of Nebraska. The assessment was conducted based on the offset distances between modeled stream crossings and original ADS on the road. Results suggested that a) stream burning in combination with D8 or D-Infinity flow direction algorithm is the best option for modeling stream flowlines from HRDEMs in an agrarian landscape; b) the smoothing effect associated with increasing the HRDEM resolution was not found significant for producing accurate drainage crossing near ADS locations; and c) D8 and D-Infinity flow direction algorithms resulted similar outputs with respect to hydrologic drainage crossing at ADS locations.