Precipitation intensity-duration curves present extreme precipitation return period amounts (inches) for various accumulation periods (24-hr, 18-hr, 12-hr, 6-hr, 3-hr, 2-hr, 1-hr) and recurrence intervals (1-yr, 2-yr, 5-yr, 10-yr, 25-yr, 50-yr, 100-yr) in 15 regions across New York. Each region is composed of individual stations that are geographically juxtaposed and observe similar extreme storm intensities. It is estimated that precipitation events equal to or greater than the magnitudes presented in these graphs will be separated, on average, by the number of years specified by each recurrence interval.
Graphs are generated for a user-specified recurrence interval and selected region of the state. Each graph includes 3 intensity-duration curves representing three individual stations that are associated with the lowest, median and highest return period amounts within the selected subregion. These curves represent return period amounts at individual points within the subregion. A fourth curve may be added to the graph by the user that represents a ‘regional’ intensity-duration curve, in addition to the 3 ‘point’ intensity-duration curves. The return period amounts associated with the ‘point’ intensity-duration curves represent precipitation magnitudes and frequency expected at individual locations across the region. The return period amounts associated with the ‘regional’ intensity-duration curve represent the precipitation magnitudes that are expected to occur with the indicated frequency anywhere within the region of interest (not restricted to a fixed location). By its definition, ‘regional’ return period amounts are always greater than or equal to the maximum ‘point’ return period amounts computed in the region.