Duration - Duration is the length of time of a rainfall event. The Flow Nomograph is a diagram used to predict the amount of flow within a channel based on the duration and intensity of rainfall. Uses rainfall data and watershed properties such as watershed area, slope, development and imperviousness to output a streamflow hydrograph. The area under the hydrograph is equal to the total volume of water passing the point. The area under the hyetograph is equal to the total or cumulative rainfall.
Intensity gives a relative figure of the severity of rainfall during a given duration of rainfall.
The reflectivity values can be empirically converted to rainfall amounts using a Z-R Relationship. Weather radar can be used to measure wind speeds and rainfall rates. Rain gage - Device that measures rainfall. Often, rain and stream gages are located together. They are shown on the map below as red circles, numbered from 400 to 490.