---
description: Urban runoff simulation option
---

# urb\_ro

Most large watersheds and river basins contain areas of urban land use. Estimates of the quantity and quality of runoff in urban areas are required for comprehensive management analysis. SWAT+ calculates runoff from urban areas with the SCS curve number method or the Green & Ampt equation. Loadings of sediment and nutrients are determined using one of two options. The first is a set of linear regression equations developed by the USGS (Driver and Tasker, 1988) for estimating storm runoff volumes and constituent loads. The other option is to simulate the build-up and wash-off mechanisms, similar to SWMM (Storm Water Management Model; Huber and Dickinson, 1988).&#x20;

| Option            | Description                 |
| ----------------- | --------------------------- |
| usgs\_reg         | USGS regression equations   |
| buildup\_washoff  | build-up/wash-off algorithm |

#### References

> Driver and Tasker (1988)
>
> Huber and Dickinson (1988)
