What is SCS curve method?

The SCS curve number method is a simiple, widely used and efficient method for determining the approxient amount of runoff from a rainfall even in a particular area. The curve number is based on the area’s hydrologic soil group, land use , treatment and hydrologic condition.

What is SCS unit hydrograph method?

The US SCS Method Hydrological Boundary is a hydrological model for determining runoff from rainfall for a subcatchment using the United States Soil Conservation Service (US SCS) unit hydrograph method. It is used as an upstream boundary condition producing output equivalent to a Flow Time Boundary.

How do you plot a hyetograph in Excel?

One can generate such a representation in MS Excel by selecting the ‘Excess Rainfall Hyetograph (in)’ column, and apply the ‘Insert’ –> ‘Charts/Column/2D’ option. Right click on the chart area, and go to ‘Select Data’, and edit the ‘horizontal axis labels’ by selecting the range of data in ‘Time (h)’ column.

How do you calculate a hyetograph?

4. Convert to a hydrograph

Multiply the rainfall excess by the catchment area (converts rainfall to a volume)
Divide by the time step (to calculate volume per unit time)
Ensure flow is allocated to the correct time step – the rainfall during a time step produces the instantaneous flow at the end of the time step.

What is SCS runoff?

The SCS Runoff equation is used with the SCS Unit Hydrograph method to turn rainfall into runoff. It is an empirical method that expresses how much runoff volume is generated by a certain volume of rainfall.

What is rainfall Hyetograph?

A hyetograph is a graphical representation of the distribution of rainfall intensity over time. The maximum intensity may not be reached as uniformly as shown in the SCS hyetographs.

How is excess rainfall hyetograph obtained?

Therefore, in order to know how much rainfall is actually contributing to the direct runoff, we much subtract the losses or abstractions from the total rainfall. The hyetograph that we get after subtracting losses from the actual rainfall is called the excess rainfall hydrograph.

How is effective rainfall calculated in a hyetograph?

The effective rainfall hyetograph, for which the runoff is to be calculated using the unit hydrograph, is obtained by deducting initial and Version 2 CE IIT, Kharagpur Page 10 infiltration losses from the recorded rainfall. This effective rainfall hyetograph is divided into blocks of T-hour duration.

What is the SCS runoff equation?

The relationship that is used by NRCS is: la = 0.2 S. and collecting terms produces the SCS runoff equation: Q = (P – 0.2 S)2 /(P + 0.8 S) July 1997 Page 16 Engineering Hydrology Training Series During development, la was measured at sites that had both continuous rainfall and runoff records.

What is the full form of SCS CN *?

This research aims to determine the runoff depth using the Soil Conservation Service Curve Number (SCS-CN) method with Geographic Information Technique (GIS). The curve number method was used to estimate the runoff depth for selected storm events in the watershed.