Rational method and hydrographs estimate peak flows.
Rational method Q=CiA estimates peak flow for small catchments; unit hydrograph, SCS curve number and hydrological models (HEC-HMS) generate runoff hydrographs. Time of concentration and losses matter. Urbanisation increases peaks and volumes.
A 10 ha paved site at 100 mm/h rainfall yields about 2.5 m³/s.
Rainfall-runoff methods estimate peak flows, which are needed to size culverts, channels and detention systems.
Rational method and hydrographs estimate peak flows.
Rainfall-runoff methods estimate peak flows, which are needed to size culverts, channels and detention systems.
A simple formula for peak runoff that multiplies the runoff coefficient, rainfall intensity and catchment area, and it suits small catchments.
A graph of flow against time at a point in a river, showing how the flow rises and falls after rainfall.
Typical applications include estimating the peak flow from a small urban catchment using the rational method, building a hydrograph for a river basin after a storm and designing a detention basin to limit runoff to a set rate.
Study "Hydrology" first (topic 74 of 112 in Civil & Structural). It covers the groundwork this topic builds on.
Runoff coefficient C. Detention basins. Routing.
A 10 ha paved site at 100 mm/h rainfall yields about 2.5 m³/s.
The next topic is "Open channel design", which builds directly on this one.
It is classed as Intermediate in Civil & Structural (topic 75 of 112). It is an intermediate topic. Work through the beginner topics in Civil & Structural first.
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