International Journal of Agricultural Engineering

Harshvardhan Baghel ¹

Affiliations
1 Development and Soil Conservation, Panchayat Samiti, Pindwara, Sirohi (Rajasthan), IN

Abstract

For most water engineering projects, estimation of peak intensity of rainfall for different return periods using IDF curves are necessary. These curves are pre-requisite for planning, design, management of various hydraulic structures, urban storm water drainage and water conservation structures. IDF curves can be developed through the application of appropriate statistical distributions based on the historic records of rainfall data. In this paper 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 best fit distribution. 28 years (1986-2014) of rainfall mass curves have collected and analyzed to get rainfall intensities for various durations from raingauge station installed in Meteorological Observatory, College of Technology and Engineering campus, Udaipur. Around 03 different probability distributions model (Gamble’s extreme value type I, Logpearson type III, Normal distribution) were used to evaluate maximum rainfall intensity for various durations. Kolmogorov- Smirnov and Chi-squared tests were used for the goodness of fit of the probability distributions. Results showed that Gumbel distribution found to be have least critical values for both the tests for all durations hence consider as the best fit distribution for given sample population. The derived precipitation intensities were utilized for generation of intensity duration frequency curve and equation. A nomograph has also developed with 03 parallel parameter scale using method suggested by Luzzadar (1964) to represent this relationship in a graphical form.

Keywords

Chi-square, Kolmogorov-smirnov, Nomograph, Idf Equation

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Harshvardhan Baghel ¹

Affiliations
1 Office of Executive Engineer Watershed Development and Soil Conservation, Panchayat Samiti, Pindwara, Sirohi (Rajasthan), IN

Abstract

Rainfall rarely occurs uniformly over a large area. Variations in intensity and total depth of fall occur from the centers to the peripheries of storms. Rainfall depth is decreases from center of the eye of the storm to its peripheries. Knowing the magnitude of this centric point rainfall is very important for water resource or water conservation engineers. Using the temporal and spatial information of the storm, maximum rainfall depth in each area and corresponding duration (1 day, consecutive 2, 3 and 4 days) can be obtained. Daily rainfall data and locations from 17 raingauge covering entire Udaipur district for the period of 41 years is collected. The isohyets maps of one to four day duration were drawn for dominant and severe most storms using Arcmap 10.3. Calculating area between two isohyet lines the average rainfall of each area (covering two isohyets) can be calculated. A curve is drawn between maximum depth of rainfall and coverage area for various durations. The curves showed that the ratio of the amount of rainfall at the center to the 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 s are 0.687, 0.785 and 0.803 for 01, 02, 03 and 04 day, respectively.

Keywords

Arcmap 10.3, Isohyets, IDW, Reclassifying

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