Hydrology Pro

Hydrology Pro works out how much of a storm runs off a catchment, how fast it gathers and how high it peaks, and gives you the chart and a PDF report to go with it. It is made for civil, drainage and water resources engineers, and for students of hydrology.

EIGHT METHODS

• Rational method: peak discharge of a small catchment, with the frequency factor for rarer storms.
• Time of concentration: Kirpich, Kerby, the NRCS lag equation, the FAA equation and Bransby Williams.
• Runoff depth: the NRCS (SCS) curve number method, with the runoff volume, retention and initial abstraction.
• Unit hydrograph: the NRCS triangular and curvilinear hydrographs, with the peak, the time to peak and a table of ordinates.
• Rainfall intensity: an intensity-duration-frequency curve with your coefficients, with the intensity and depth at standard durations.
• Detention storage: a first estimate of the volume that holds an inflow peak back to an allowable release.
• Risk and return period: the chance of exceedance in a design life, or the return period for a risk you accept.
• Frequency analysis: the Gumbel distribution of annual maxima, with design values at standard return periods.

FEATURES

• Metric and English units: millimetres and hectares, or inches and acres. Switching converts what you typed.
• A chart with every result, with the solved state marked.
• Notes that say what each method was derived for, and when a result is outside that range.
• PDF reports with the inputs, results, notes, chart and tables.
• Save calculations by name and open them again later.
• Works offline. No account, no ads, no tracking.

The results are for preliminary design and checking. Coefficients and curve numbers depend on the catchment: confirm them from local data and standards, and have the design reviewed by a qualified engineer.