HYDROLOGY FORMULATOR - Your Complete Professional Hydrology Engineering Companion

Built for hydrologists, civil engineers, environmental scientists, and students, Hydrology Formulator delivers powerful calculations and comprehensive reference tools in one intuitive app. Whether you are analyzing groundwater flow, designing stormwater systems, calculating pipe hydraulics, or modeling sediment transport, this app has you covered.

22+ Calculator Categories Covering Every Aspect of Water Science:

• Infiltration & Recharge (17): Green-Ampt, Horton, and Philip infiltration models, Holtan's Model, porosity, hydraulic conductivity, groundwater recharge, mean pore velocity, specific discharge, volumetric water content, and more
• Evaporation & Transpiration (8): Penman-Monteith ET0, Blaney-Criddle ET, Thornthwaite PET, crop evapotranspiration, saturation vapor pressure, evaporation rate of lake, and relative humidity
• Open Channel Flow (12): Manning's Equation (SI & US), Chezy Equation, Froude Number, hydraulic radius, hydraulic jump energy loss & sequent depth, critical depth, specific energy, and Reynolds Number
• Pipe Flow (7): Darcy-Weisbach Equation, Hazen-Williams velocity (SI & US), Reynolds Number, water hammer pressure, continuity equation, and minor head loss
• Stormwater & Watershed (9): SCS Curve Number runoff, SCS peak discharge, IDF rainfall intensity, Kirpich time of concentration, Gumbel extreme value, detention storage volume, NRCS lag time, and composite curve number
• Pumps & Water Supply (7): Total dynamic head, water horsepower, brake horsepower, NPSHa, and all three affinity laws for flow, head, and power
• Weirs & Orifices (6): Rectangular weir (SI & US), V-Notch weir, broad-crested weir, orifice flow, and spillway discharge
• Water Flow (10): Water flow rate, velocity of water, volume of water flow, 90° V-Notch calculations, and pipe total diameter in US and metric
• Surface Runoff (6): Average velocity, runoff, travel time, sheet flow travel time, and hourly rate of rainfall
• Water Balance (2): Water balance equation and storage continuity
• Groundwater (7): Darcy's Law, Thiem Equation, Cooper-Jacob drawdown, Dupuit well flow, radius of influence, and storage properties
• Soil Pollution (5): Groundwater pore velocity, effective diffusion, hydrodynamic dispersion, aquifer parameter, and variance of pore velocity
• River Pollution (7): River oxygen deficit, critical time & distance for oxygen deficit, re-aeration constants, dissolved oxygen, river flow, and water temperature
• Lake Pollution (4): Waste entering, equilibrium concentration, settling loss rate, and particle deposition rate
• Sediment Transport (4): Shields parameter, bed shear stress, Stokes' Law settling velocity, and Meyer-Peter Müller bedload
• Snow Hydrology (2): Snow water equivalent and degree-day snowmelt
• Culvert Hydraulics (2): Culvert headwater (outlet control) and outlet control head loss
• Flood Routing (1): Muskingum routing
• Pollution (1): Required to clean beach

Extensive Conversion Library:

• 16 conversion categories including Pressures, Flows, BTU, Linear, Square, Cubic, Weights, Power, Watts, Horsepower, and more
• Hydrology-specific conversions for flow rates, liquid measures, and hydraulic calculations
• 8 temperature scales: Celsius, Fahrenheit, Kelvin, Rankine, Réaumur, Newton, Delisle, and Rømer
• Complete metric conversion suite with hundreds of unit conversions

Area Formulas:

• Built-in area calculation tools for common geometric shapes
• Useful for watershed area calculations and drainage basin analysis

Professional Features:

• Save and compare calculation results
• Switch between US (Imperial) and Metric units
• Clean, intuitive interface designed for field and office use
• Dark mode interface
• Works offline - no internet required

Hydrology Formulator is FREE to download with access to core calculators and conversions. Upgrade to Premium to unlock Groundwater, Pollution, Sediment Transport, Snow Hydrology, Culvert Hydraulics, and Flood Routing calculators.