UM-25 : Unit hydrograph analysis

Abstract

This user's manual gives the details of twenty one computer programmes to carry out unit hydrograph analysis. These computer programmes are considered to be in five different categories dealing with:

(i) Processing and analysis of precipitation data),

Computation of discharge and rating curve analysis,

(iii) Computation of excess rainfall and direct surface runoff,

(iv) Unit hydrograph derivation, and

(v) Reproduction of direct surface runoff and estimation of flood hydrograph.

There are five programmes, GAPF.FOR, DOUBLE.FOR, THIES.FOR, ISO.FOR and DAILY.FOR, for processing and analysis of precipitation data. The programme GAPF.FOR is used for filling up the missing record using Normal ratio method. The programme DOUBLE.FOR performs the computations involved in consistency check using double mass curve analysis. The average rainfall for the storm are computed using Theissen polygon method through the programme THIES.FOR. The programme ISO.FOR calculates the variation of depth with area over the catchment using Isohyets Method. While the programme DAILY.FOR is used for the distribution of daily rainfall at non-recording raingauge stations into hourly rainfall and the computation of average hourly rainfall using Theissen polygon method.

In the second category there are three computer programmes namely VEL.FOR, RATING.FOR and GAUGE.FOR to carry out the computation of discharge and rating curve analysis. The programme VEL.FOR calculates the discharge from velocity measurement taking number of sections and different number of velocity measurements in each section. The stage-discharge relationship b

(rating curve)