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.