UM-22 : Graphical representation of information related with floods

Abstract

For a given catchment, information related with floods are many. Informations such as statistical summary, check for validity of randomness, presence of outliers/inliers, satisfactory design flood estimates, standard error of estimates and their confidence bands are of importance to any designer. Some of the information can be tabulated and some informations like the relationship between quantile estimate and return periods (or reduced variates) for a chosen probability model can be well represented graphically.

Generalised software package 'GRIF' (Graphical Representation of Information related with Floods) has therefore specifically been developed to assist the designer in obtaining necessary desired information from the observed annual peak floods. This package written in FORTRAN has the following features.

i) It runs in a user-friendly mode and gives adequate flexibility to the designer for exercising his choice/options.

ii) It brings out statistical summary of data either in natural or log domain or even both.

Iii)The designer has the option to go through the analysis for outlier/inliers, view the modifications and either accept or reject the analysis before going over to next module.

iv)Analysis for checking the persistence structure of data is available to the user.

v)It allows the designer to choose from amongst potential distribution with different parameter estimation techniques.

vi) Quantile estimates together with their standard errors at specified return periods with facility to compute quantiles to additionally specified return periods are available to the user.

vii) Options are also available to the user LO see graphical plot of quantiles on the terminal.

Operational logic represented through a flow chart detailed description of various subroutines and procedures used alongwith a sample input and output are given in the user's manual.