2.7.4. Conversion of the Duration of Unit Hydrograph Preparing unit hydrographs for a given catchment and covering wide range of durations is usually not possible due to lack of data. Therefore, one needs to convert an existing or derived unit hydrograph for one storm duration (say, D hours) to another (say, nD hours) that could be either shorter (to better cope with spatial and intensity variations) or longer (to reduce the computational work and also recognizing the coarseness of the available data). The following two methods are used for the conversion of the duration of a given unit hydrograph:
