Hydrological Analysis of Rainfall of Udaipur
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Date
2019-09
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Publisher
MPUT, UDAIPUR
Abstract
Rainfall is a prime input for various engineering design such as hydraulic
structures, water conservation structures, bridges and culverts, canals, storm water
sewer and road drainage system. The detailed statistical analysis of each region is
essential to estimate the relevant input value for design and analysis of engineering
structures and also for crop planning. The present study comprises three statistical
analysis viz. frequency analysis of daily rainfall, development of intensity duration
frequency curves and development of depth area duration curves. The daily rainfall
data for a period of 56 years is collected to evaluate designed value of rainfall using
probability distribution models. Around 07 different probability distributions
(Gamble’s extreme value type I, Logpearson type III, Lognormal, Normal,
Exponential, Pearson type III and Gamma distribution) were used to evaluate
maximum daily rainfall (mm). Kolmogorov-Smirnov and Chi-squared tests were used
for the goodness of fit of the probability distributions. Results showed that Lognormal
distribution found to be have least parameter values for both the tests hence consider
as the best fit distribution for given sample population. Also maximum daily expected
value of rainfall for various return periods were evaluated using all distribution model
under consideration.
For developing IDF curve, a mathematical relationship has been developed
between maximum intensity of rainfall and Return Period ( 5, 10, 25, 50, 100, 200,
300, 400, 500 and 1000 years) for various rainfall duration (1, 2, 3, 6, 12 and 24 hour)
using Gumbel’s extreme value type I Distribution. The derived precipitation depth is
utilized for generation of intensity duration frequency curve. The Chi-squared and
Kolmogorov-smirnov tests were used to check goodness-of-fit of sample data. The
observed values of rainfall intensity are also compared with values calculated from
Rambabu’s empirical equation. Result showed that a deviation of 16.29% (less) was
observed for calculated values compare to observed values. A relationship was also
derived between maximum rainfall intensity duration and return period of rainfall
using graphical method.
For developing depth area duration curve, isohyet maps were prepared after
collection of data and information at rain gauge stations installed in Udaipur district
and the dominant and maximum rainfall for durations of one to four days were
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selected. The relationship between rainfall and elevation was investigated for multiple
durations, inverse distance with power 01 to 03 were evaluated to draw isohyet maps
in Arcmap 10.3 software. The depth area duration curve were drawn after calculating
average depth of rainfall increment with isohyet expansion. The ratio of rainfall at the
center to the amount of rainfall at an area of 11724 km2 is 2.13, 1.51, 1.45 and 1.47
for the durations of 1, 2, 3, and 4 days respectively. Areal reduction factor is
calculated which can be used to convert maximum average depth of rainfall into
maximum point rainfall. ARF’s are 0.687, 0.764, 0.785 and 0.803 for 01, 02, 03 and
04 day respectively.
Description
Hydrological Analysis of Rainfall of Udaipur
Keywords
Citation
Baghel H. And Mittal H.K.