Table of Contents

## What is the SCS method?

The SCS-CN method predicts runoff from an expression for a rainfall-runoff curve that varies according to a single parameter called the curve number (CN). The dimensionless CN parameter describes the antecedent potential water retention of a watershed [Hawkins, 2014].

## What is Curve Number in Swat?

The curve number method in SWAT relates runoff to soil type, land use, and management. On the other hand, Green-Ampt (1911) is an infiltration. equation. It assumes a homogeneous soil profile and. antecedent soil moisture, total saturation above the wetting.

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### What is antecedent moisture condition?

Antecedent moisture is the relative wetness or dryness of a sewershed, which changes continuously and can have a very significant effect on the flow responses in these systems during wet weather. Antecedent moisture conditions are high when there has been a lot of recent rainfall and the ground is moist.

### How is drainage volume calculated?

To calculate the volume of water that needs to be stored, multiply the amount of runoff from each drainage zone by 15. The runoff for each zone was in gallons per minute. Multiplying by 15 minutes leaves you with the amount of gallons to be stored.

**How do you calculate drain capacity?**

#### Is there a computer program for TR-55?

Since the initial publication predated the widespread use of computers, TR-55 was designed primarily as a set of manual worksheets. A TR-55 computer program is now available, based closely on the manual calculations of TR-55. 2) TR-55 utilizes the SCS runoff equation to predict the peak rate of runoff as well as the total volume.

#### What does TR55 stand for?

TR-55, Urban Hydrology for Small Watersheds Technical Release 55 (TR-55) presents simplified procedures to calculate storm runoff volume, peak rate of discharge, hydrographs, and storage volumes required for floodwater reservoirs. These procedures are applicable in small watersheds, especially urbanizing watersheds, in the United States.

**What is the TR-55 urban hydrology?**

Please contact us if you have problems or questions. Technical Release 55 (TR-55) Urban Hydrology for Small Watersheds was first issued in January 1975 as a simplified procedure to calculate the storm runoff volume, peak rate of discharge, hydrographs and storage volumes required for storm water management structures (SCS, 1975).

## Where can I find the NRCS TR-55 manual?

You can download the TR-55 Manual here. (2MB PDF format) The complete software and documentation is available from the NRCS TR-55 web page . Also see the NRCS Win-TR-55 web page.