Stormwater 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 […]
Read MoreComposite Curve Number Calculator with Unconnected Impervious Area Composite Curve Number Calculator with Unconnected Impervious Area Calculate the composite curve number for a watershed that has an unconnected impervious area using: \[ CN_{comp} = f_{UIA} \times CN_{UIA} + \left(1 – f_{UIA}\right) \times CN_{perv} \] * Enter the percentage of unconnected impervious area, the curve number […]
Read MoreComposite Curve Number Calculator with Connected Impervious Area Composite Curve Number Calculator Calculate the composite curve number for a watershed with a connected impervious area using: \[ CN_{comp} = f_{CIA} \times 98 + (1 – f_{CIA}) \times CN_{perv} \] * Enter the percentage of connected impervious area (CIA%) and the curve number for the pervious […]
Read MoreKelvin Equation Vapor Pressure Change Calculator Kelvin Equation Vapor Pressure Calculator Calculate the vapor pressure over a curved surface using the Kelvin Equation: \[ \ln\left(\frac{p}{p_0}\right) = \frac{2\gamma V_m}{R\,T\,r} \] * Enter the flat surface vapor pressure \( p_0 \) (Pa), surface tension \( \gamma \) (N/m), molar volume \( V_m \) (m³/mol), radius \( r […]
Read MoreFourier Number Calculator Fourier Number Calculator Calculate the Fourier number using the formula: \[ Fo = \frac{\alpha\, t}{L^2} \] * Enter thermal diffusivity \( \alpha \) (m²/s), time \( t \) (s), and characteristic length \( L \) (m). Step 1: Enter Parameters Thermal Diffusivity, \( \alpha \) (m²/s): Example: 1.2e-5 m²/s Time, \( t […]
Read Morevan der Waals Coefficients Calculator Calculate the van der Waals constants \( a \) and \( b \) using the critical properties of a substance. \[ a = \frac{27 R^2 T_c^2}{64 P_c} \quad \text{and} \quad b = \frac{R T_c}{8 P_c} \] * Enter the critical temperature (K) and critical pressure (atm). Step 1: Enter Critical […]
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