Modified priority flood and global slope enforcement algorithm for topographic processing in physically based hydrologic modeling applications

We present a topographic processing tool, PriorityFlow, designed to improve the topographic input datasets which are required for physically based hydrologic models. PriorityFlow is available on GitHub, combines multiple processing approaches, and includes several key innovations over previous work: (1) a novel approach for incorporating a-priori stream network information with priority flood routing DEM processing, (2) improved slope calculations that incorporate flow directions, (3) options for incorporating slopes perpendicular to the primary flow direction, (4) more flexible options for defining subbasins and enforcing slopes along stream reaches. Here we document the approach and demonstrate the impact of topographic processing choices on hydrologic simulations. Results demonstrate that the modified priority flood algorithm can better reproduce observed stream networks without relying on traditional stream burning approaches. Additionally, we demonstrate the impact of slope processing options on runoff timing and magnitude. Specifically, we highlight the sensitivity of the hydrograph to slope processing choices along stream reaches.