*2.4. Scenario Analysis*

We evaluated the impact of paving roads on runoff and sediment yield using the calibrated model. The simulation paved only those roads in the AnnAGNPS cells that generated 50% of the total sediment yield at the LLCW scale (hotspots) under current conditions. For the scenario analysis, we assumed that the *CN* is the same for all paved roads (*CN* = 98), and that gully sediment yield is zero since gully erosion occurred solely on the dirt road network within the LLCW [9,14]. Composite curve numbers were calculated for unpaved and paved conditions following Gudino-Elizondo et al. [14]. The scenarios were run for 2004–2017 and the impact on sediment and runoff were determined by the change in simulated sediment load, and total and peak runoff between the current conditions and the paving scenario. The change in total and peak discharge were calculated for the largest 14 storm events (event-total precipitation ranging from 28 to 81 mm).
