4-Unit Hydrograph Analysis Using Personal Computer.

Abstract

Engineers have been using computers for years in design and research, However, this use was limited to large main frame and mini computers. Recently the inexpensive personal computers (PCs or micro computers) have been widely introduced and their applications are becoming more and more popular in the field of water resources for the preparation of the detailed project reports. Moreover, many companies are selling standard software, specially developed for the personal computers, but their applications are mostly limited to routine works. However, there is a lack of standardized PC based computer softwares to solve the specific problems concerning the water resources planning, design and management. Thus, there is an urgent need to develop some of the simple and popular PC based computer softwares which could be easily utilized for providing the solutions of some specific hydrological problems.

Unit hydrograph technique is one of the popular and versatile techniques available in literature for various uses e.g. estimation of design flood, filling the missing runoff for ungauged catchments, and the real time flood forecasting etc. Unit hydrograph is a simple function which converts the excess rainfall to the direct surface runoff using the principle of linearity. Therefore, its determination forms one of the principle tasks in the area of flood estimation based on unit hydrograph approach.

In this paper PC based computer softwares to carry out unit hydrograph analysis for gauged catchments have been described. The sofiwares are developed in FORTRAN language and implemented and tested on IBM compatible personal computer. The paper also describes the methodology for the application of unit hydrograph to estimate the design flood. The results obtained from these programmes are subjected to the assumptions and limitations inherent in the respective techniques on which the programmes are developed.