Kerby’s Time of Concentration Calculator Kerby’s Time of Concentration Calculator Calculate the time of concentration using Kerby’s Equation: \[ T_c = \frac{0.00045\, L^{0.85}}{\sqrt{S}} \] * Enter the watercourse length \( L \) (ft) and the slope \( S \) (ft/ft). Step 1: Enter Parameters Watercourse Length, \( L \) (ft): Example: 1000 ft Slope, \( […]
Read MoreFAA Time of Concentration Calculator FAA Time of Concentration Calculator Calculate the time of concentration using the FAA formula: \[ T_c = \frac{L}{190\sqrt{S}} \] * Enter the watercourse length \( L \) (ft) and the slope \( S \) (ft/ft). Step 1: Enter Parameters Watercourse Length, \( L \) (ft): Example: 1000 ft Slope, \( […]
Read MoreStormwater Runoff Volume Calculator Stormwater Runoff Volume Calculator Calculate the total runoff volume using the NRCS (SCS) method. First, determine the runoff depth using: \[ S = \frac{25400}{CN} – 254 \quad \text{and} \quad Q = \begin{cases} 0, & P \le 0.2S \\ \frac{(P-0.2S)^2}{P+0.8S}, & P > 0.2S \end{cases} \] Then, convert runoff depth (mm) to […]
Read MoreDetention Storage Volume Calculator Detention Storage Volume Calculator Calculate the detention storage volume using the Rational Method Hydrograph: \[ Q = C \times I \times A \quad \text{and} \quad V = \frac{Q \times t}{2} \] (with \( t \) in seconds) * Enter the runoff coefficient (C), rainfall intensity (in/hr), drainage area (acres), and rainfall […]
Read MoreRational Formula Runoff Depth Calculator Rational Formula Runoff Depth Calculator Calculate the runoff depth using the formula: \[ D = C \times I \times t \] * Enter the runoff coefficient (0–1), rainfall intensity (mm/hr), and duration (hr). Step 1: Enter Parameters Runoff Coefficient, \( C \): Example: 0.5 Rainfall Intensity, \( I \) (mm/hr): […]
Read MoreStormwater Peak Discharge Calculator Stormwater Peak Discharge Calculator Calculate the peak discharge using the Rational Method: \[ Q = C \times I \times A \] * Enter the runoff coefficient (C), rainfall intensity (I in in/hr), and drainage area (A in acres). Step 1: Enter Parameters Runoff Coefficient, \( C \): Example: 0.5 (dimensionless, between […]
Read MoreRainfall Intensity Calculator Rainfall Intensity Calculator Calculate rainfall intensity using the formula: \[ I = \frac{P}{t} \] * Enter the rainfall depth (in mm) and the duration (in hours). Step 1: Enter Data Rainfall Depth, \( P \) (mm): Example: 50 mm Duration, \( t \) (hours): Example: 1 hour Calculate Intensity Calculated Rainfall Intensity […]
Read MoreNRCS Travel Time Calculator NRCS Travel Time Calculator Estimate the time of concentration (travel time) using the NRCS/Kirpich equation: \[ T_c = 0.0078 \frac{L^{0.77}}{S^{0.385}} \] * Enter the watercourse length \( L \) (ft) and the slope \( S \) (ft/ft). Step 1: Enter Parameters Length \( L \) (ft): Example: 1000 ft Slope \( […]
Read MoreWeighted Curve Number Calculator for a Basin Weighted Curve Number Calculator for a Basin Calculate the overall curve number of a basin by weighing the curve numbers of subbasins by their areas: \[ CN_{weighted} = \frac{\sum (CN_i \times \text{Area}_i)}{\sum \text{Area}_i} \] * Enter the area (in consistent units) and curve number for each subbasin. Step […]
Read MoreWeighted Curve Number Calculator for a Basin Weighted Curve Number Calculator for a Basin Calculate the overall curve number of a basin by weighing the curve numbers of subbasins by their areas: \[ CN_{weighted} = \frac{\sum (CN_i \times \text{Area}_i)}{\sum \text{Area}_i} \] * Enter the area (in consistent units) and curve number for each subbasin. Step […]
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