Unit hydrograph models dealing with the representaion of a watershd as linear time invariant system, response function and convolution, unit hydrograph characteristics, unit hydrograph derivation, synthetic unit hydrographs, gamma distribution, Snyder, NRCS, and Clark unit hydrograph models, instantaneous unit hydrographs, instantaneous unit hydrograph models, parameter estimation, and application of unit hydrographs and instantaneous unit hydrographs, S-hydrographs.