MATHEMATICAL MODELS FOR GENERATING DAILY AND HOURLY RAINFALL SEQUENCE

Abstract

In hydrological design and operation of the projects, long term sequences of river flows (daily as well as flood flows) are necessary. However such information is often scanty in some , catchments. River flow data in such cases can be augmented by reference to records of rainfall data and converting these to river floods. Mathematical models can be used to generate seque-nces of rainfall from available records of rainfall data when rainfall record itself is not sufficiently 1 age. Various methods of generating synt'letic rainfall s,ec~uences are available in literature. These methods have been reviewed and form the basis for developing and applying appropriate models for synthesizing the rainfall sequences . Briefly the models are required to : (i) generate a senufnce of wet and dry days for a specified period. (ii) Synthesize amounts of daily rainfall on synthetic wet days in the specified period. (iii)Synthesize storm rainfall and interior of storms. (iv) Compare the statistical characteristics of the sequence. Historical record of daily rainfall data for period of i twenty years and records of storm patterns for a period of years at the Roorkee rain gauge station (U.P.--India) have been used in t. this study.