Lag Time of 1-h Unit Hydrograph Solution

STEP 0: Pre-Calculation Summary
Formula Used
Lag Time of a 1-h Unit Hydrograph = 1.56/((Peak discharge of a D-h Unit hydrograph/Area of Catchment)^0.9)
Tp1 = 1.56/((Qpd/A)^0.9)
This formula uses 3 Variables
Variables Used
Lag Time of a 1-h Unit Hydrograph - (Measured in Hour) - Lag Time of a 1-h Unit Hydrograph is the time interval from the midpoint of the rainfall excess to the peak.
Peak discharge of a D-h Unit hydrograph - (Measured in Cubic Meter per Second) - Peak discharge of a D-h Unit hydrograph is the maximum volume flow rate displays in a unit hydrograph.
Area of Catchment - (Measured in Square Meter) - Area of catchment is the area from which rain flows into a particular river or lake.
STEP 1: Convert Input(s) to Base Unit
Peak discharge of a D-h Unit hydrograph: 129031 Cubic Meter per Second --> 129031 Cubic Meter per Second No Conversion Required
Area of Catchment: 3 Square Kilometer --> 3000000 Square Meter (Check conversion here)
STEP 2: Evaluate Formula
Substituting Input Values in Formula
Tp1 = 1.56/((Qpd/A)^0.9) --> 1.56/((129031/3000000)^0.9)
Evaluating ... ...
Tp1 = 26.4794567436257
STEP 3: Convert Result to Output's Unit
95326.0442770526 Second -->26.4794567436257 Hour (Check conversion here)
FINAL ANSWER
26.4794567436257 26.47946 Hour <-- Lag Time of a 1-h Unit Hydrograph
(Calculation completed in 00.004 seconds)

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Peak Discharge of D-h Unit Hydrograph given Lag Time
Go Peak discharge of a D-h Unit hydrograph = (Area of Catchment)*(1.56/Lag Time of a 1-h Unit Hydrograph)^(1/0.9)
Catchment Area given Lag Time of 1-h Unit Hydrograph
Go Area of Catchment = Peak discharge of a D-h Unit hydrograph*(Lag Time of a 1-h Unit Hydrograph/1.56)^(1/0.9)
Lag Time of 1-h Unit Hydrograph
Go Lag Time of a 1-h Unit Hydrograph = 1.56/((Peak discharge of a D-h Unit hydrograph/Area of Catchment)^0.9)
Catchment Area for Peak Discharge of Weighted Mean Slope Lesser than 0.0028
Go Area of Catchment = (Peak discharge of a D-h Unit hydrograph/(37.4*Weighted Mean Slope^(2/3)))^(4/3)
Weighted Mean Slope given Peak Discharge of D-h Unit Hydrograph
Go Weighted Mean Slope = (Peak discharge of a D-h Unit hydrograph/(37.4*Area of Catchment^(3/4)))^(3/2)
Peak Discharge of D-h Unit Hydrograph for Weighted Mean Slope Lesser than 0.0028
Go Peak discharge of a D-h Unit hydrograph = 37.4*Area of Catchment^(3/4)*Weighted Mean Slope^(2/3)
Lag Time of 1-h Unit Hydrograph given Duration of Rainfall Excess
Go Lag Time of a 1-h Unit Hydrograph = Duration of Excess Rainfall in Hours/1.1
Duration of Rainfall Excess
Go Duration of Excess Rainfall in Hours = 1.1*Lag Time of a 1-h Unit Hydrograph
Catchment Area given Peak Discharge of D-h Unit Hydrograph
Go Area of Catchment = (Peak discharge of a D-h Unit hydrograph/1.79)^(4/3)
Peak Discharge of D-h Unit Hydrograph
Go Peak discharge of a D-h Unit hydrograph = 1.79*Area of Catchment^(3/4)

Lag Time of 1-h Unit Hydrograph Formula

Lag Time of a 1-h Unit Hydrograph = 1.56/((Peak discharge of a D-h Unit hydrograph/Area of Catchment)^0.9)
Tp1 = 1.56/((Qpd/A)^0.9)

What is meant by Unit Hydrograph?

The Unit Hydrograph is the hydrograph that results from a unit (e.g. 1 inch) excess rainfall uniformly over the watershed at a uniform rate during a given period. Unit hydrographs assume a uniform distribution of rainfall over the catchment and uniform intensity during the duration of rainfall excess. In practice, these two conditions are never satisfied.

What is Basin lag?

Basin lag time, defined as the elapsed time between the occurrences of the centroids of the effective rainfall. and of the storm runoff hydrograph, is an important factor in determining the time to peak of the unit hydrograph and the intensity of peak discharge.

How to Calculate Lag Time of 1-h Unit Hydrograph?

Lag Time of 1-h Unit Hydrograph calculator uses Lag Time of a 1-h Unit Hydrograph = 1.56/((Peak discharge of a D-h Unit hydrograph/Area of Catchment)^0.9) to calculate the Lag Time of a 1-h Unit Hydrograph, The Lag Time of 1-h Unit Hydrograph is defined as the time interval from the midpoint of the rainfall excess to the peak. Lag Time of a 1-h Unit Hydrograph is denoted by Tp1 symbol.

How to calculate Lag Time of 1-h Unit Hydrograph using this online calculator? To use this online calculator for Lag Time of 1-h Unit Hydrograph, enter Peak discharge of a D-h Unit hydrograph (Qpd) & Area of Catchment (A) and hit the calculate button. Here is how the Lag Time of 1-h Unit Hydrograph calculation can be explained with given input values -> 0.007355 = 1.56/((129031/3000000)^0.9).

FAQ

What is Lag Time of 1-h Unit Hydrograph?
The Lag Time of 1-h Unit Hydrograph is defined as the time interval from the midpoint of the rainfall excess to the peak and is represented as Tp1 = 1.56/((Qpd/A)^0.9) or Lag Time of a 1-h Unit Hydrograph = 1.56/((Peak discharge of a D-h Unit hydrograph/Area of Catchment)^0.9). Peak discharge of a D-h Unit hydrograph is the maximum volume flow rate displays in a unit hydrograph & Area of catchment is the area from which rain flows into a particular river or lake.
How to calculate Lag Time of 1-h Unit Hydrograph?
The Lag Time of 1-h Unit Hydrograph is defined as the time interval from the midpoint of the rainfall excess to the peak is calculated using Lag Time of a 1-h Unit Hydrograph = 1.56/((Peak discharge of a D-h Unit hydrograph/Area of Catchment)^0.9). To calculate Lag Time of 1-h Unit Hydrograph, you need Peak discharge of a D-h Unit hydrograph (Qpd) & Area of Catchment (A). With our tool, you need to enter the respective value for Peak discharge of a D-h Unit hydrograph & Area of Catchment and hit the calculate button. You can also select the units (if any) for Input(s) and the Output as well.
How many ways are there to calculate Lag Time of a 1-h Unit Hydrograph?
In this formula, Lag Time of a 1-h Unit Hydrograph uses Peak discharge of a D-h Unit hydrograph & Area of Catchment. We can use 1 other way(s) to calculate the same, which is/are as follows -
  • Lag Time of a 1-h Unit Hydrograph = Duration of Excess Rainfall in Hours/1.1
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