How to Calculate and Solve for Expected Discharge | Flood Formulae | Irrigation Water Requirement

October 2, 2020April 21, 2024 Loveth Idoko

Last Updated on April 21, 2024

The image above represents expected discharge. To calculate expected discharge using flood formulae, three essential parameters are needed and these parameters are Constant (c), Constant (n) and Drainage Basin Area (A_d).

The formula for calculating expected discharge:

Q_p = cA_dⁿ

Where:

Q_p = Expected Discharge | Flood Formulae
c = Constant
n = Constant
A_d = Drainage Basin Area

Let’s solve an example;
Find the expected discharge when the constant is 8, the constant is 2 and the drainage basin area is 4.

This implies that;

c = Constant = 8
n = Constant = 2
A_d = Drainage Basin Area = 4

Q_p = cA_dⁿ
That is, Q_p = (8) . (4)²
Q_p = (8) . (16)
Q_p = 128

Therefore, the expected discharge is 128.

Calculating the Constant when the Expected Discharge, the Constant and the Drainage Basin Area are Given

c = ^Q_p / _{A_dⁿ}

Where;

c = Constant
Q_p = Expected Discharge | Flood Formulae
n = Constant
A_d = Drainage Basin Area

Let’s solve an example;
Find the constant when the expected discharge is 30, the constant is 3 and the drainage basin area is 2.

This implies that;

Q_p = Expected Discharge | Flood Formulae = 30
n = Constant = 3
A_d = Drainage Basin Area = 2

c = ^Q_p / _{A_dⁿ}
So, c = ³⁰ / _2³
c = ³⁰ / ₈
c = 3.75

Therefore, the constant is 3.75.

Calculating the Drainage Basin Area when the Expected Discharge, the Constant and the Constant are Given

A_d = ^Q_p / _cⁿ

Where;

A_d = Drainage Basin Area
Q_p = Expected Discharge | Flood Formulae
c = Constant
n = Constant

Let’s solve an example;
Find the drainage basin area when the expected discharge is 48, the constant is 4 and the constant is 2.

This implies that;

Q_p = Expected Discharge | Flood Formulae = 48
c = Constant = 4
n = Constant = 2

A_d = ^Q_p / _cⁿ
That is, A_d = ⁴⁸ / _4²
A_d = ⁴⁸ / ₂₅₆
A_d = 0.1875

Therefore, the drainage basin area is 0.1875.

How to Calculate and Solve for Discharge | Logarithmic Method | Irrigation Water Requirement

How to Calculate Expected Discharge Using Flood Formulae With Nickzom Calculator

Nickzom Calculator – The Calculator Encyclopedia is capable of calculating the expected discharge using Flood Formulae.

To get the answer and workings of the expected discharge using the Nickzom Calculator – The Calculator Encyclopedia. First, you need to obtain the app.

You can get this app via any of these means:

Web – https://www.nickzom.org/calculator-plus

To get access to the professional version via web, you need to register and subscribe for NGN 2,000 per annum to have utter access to all functionalities.
You can also try the demo version via https://www.nickzom.org/calculator

Android (Paid) – https://play.google.com/store/apps/details?id=org.nickzom.nickzomcalculator
Android (Free) – https://play.google.com/store/apps/details?id=com.nickzom.nickzomcalculator
Apple (Paid) – https://itunes.apple.com/us/app/nickzom-calculator/id1331162702?mt=8
Once, you have obtained the calculator encyclopedia app, proceed to the Calculator Map, then click on Agricultural under Engineering.

Now, Click on Irrigation Water Requirement under Agricultural

Now, Click on Expected Discharge under Irrigation Water Requirement

The screenshot below displays the page or activity to enter your values, to get the answer for the expected discharge according to the respective parameters which is the Constant (c), Constant (n) and Drainage Basin Area (A_d).

Now, enter the values appropriately and accordingly for the parameters as required by the Constant (c) is 8, Constant (n) is 2 and Drainage Basin Area (A_d) is 4.

Finally, Click on Calculate

As you can see from the screenshot above, Nickzom Calculator– The Calculator Encyclopedia solves for the expected discharge and presents the formula, workings and steps too.