If you are working on small catchment then I would produce a unit hydrograph from the observed rainfall and runoff data, also find the curve number for your catchment. In case your are interested in peak discharge you can use the rational method.

DO YOU HAVE THE:

The construction of a Unit hydrograph is quite simple. Use any of the techniques recommended for this purpose: (i) Shermann; (ii) Gamma Distribution Technique; (iii) US Soil & Conservation Service Technique; (iv) among many others. The problem is to validate the unit hydrograph. For this use:

A) HOURLY DATA. Do a stormwater (streamflow, Q) separation analysis using hydrograph or chemical or both techniques. Separate base (Qs) from storm (Qr) runoff. Calculate the rainfall-event Qs, Qr, and Q (mm or m3). Do this for a number of n storms. Regress Qr, Qs or Q vs P and the slope is the runoff (Qs, Qr, Q) runoff coefficient. Note Qs may not be correlated properly with P, as it is some times independent of P because its origins are from groundwater flow. Sometimes the groundwater responds to P if the water table is shallow and some times it does not as the water table is deep. CONTRAST THE UNIT HYDROGRAPH TECHNIQUE WITH MEASUREMENTS OF BOTH Q COMPONENTS. USE THE NASH-SUTCLIFFE, NSE, ESTIMATOR TO VALIDATE.

OR

B) STORM OR DAILY DATA. Transform Q in mm or m3 and correlate with P for n number of storms or rainy days. Note that most small rainfal events do not produce produce Q hence you have several options: (i) eliminate P events with Q=0; (ii) use all data but use non-linear regression; (iii) other techniques. Use this approach to construct the storm hydrograph. CONTRAST THE UNIT HYDROGRAPH TECHNIQUE WITH MEASUREMENTS OR ASSESSMENTS OF BOTH Q COMPONENTS. USE THE NASH-SUTCLIFFE, NSE, ESTIMATOR TO VALIDATE THE UNIT HYDROGRAPH TECHNIQUE.

I hope these comments can help You understand runoff production n watersheds.

Kind Regards

Jose

You can use the Rational Method

Step 1

The Rational Method is used for areas less than 50 acres. If the area you are assessing is more than 50 acres, you will have to use a coefficient table. Write down the following formula:

Q = CiA

Step 2

Find the appropriate values for each variable. In the Rational Method equation, “C” is the runoff coefficient, meaning it is your unknown. “Q” is the value for the peak rate of runoff. This value is in CFS. One CFS is equal to one cubic foot of water passing a particular point over the course of a second. “A” equals the size of the area you are measuring. “A” is measured in acres.

Step 3

Calculate the value for “i.” This is a measurement of rainfall intensity. It is measured in inches per hour. This value is calculated using a Seelye chart (see Resources) and an IDF chart. To use a Seelye chart, you need to have the length of the land and its angle of grade. Once you have this value, you can use an IDF chart to determine “i.” IDF charts vary from area to area and are based on average rainfall intensities. IDF charts are typically available from the state government. The actual agency varies from state to state. For instance, in Tennessee, the Department of Transportation releases IDF charts.

Step 4

Isolate and solve for “C.” Your altered equation should look like this:

C = Q/iA

Imene Kerraouch tu as devenu hydrologue ?

Non pas encore

Poštovani gospodine Shagun Chaudhary , Imene Kerraouch i José Návar dali su Vam odličan i tačan odgovor. Ja samo mogu potvrditi njihove predloge. Na Vama je da te podatke uskladite sa orografijom i ostalim ulaznim podacima izračunate sa postojećim obrascima i dijagramima.

Srdačan pozdrav

The definition of runoff coefficient is the ratio of runoff to rainfall during a certain period of time, usually taken as the duration of the total runoff response. so for example, if you have a one hour rainfall followed by a 30 hour runoff response, then divide the rainfall volume in mm or m3 by the runoff volume in mm or m3.