PRAXIS SCIENCE AND TECHNOLOGY JOURNAL
ISSN NO: 0369-8394
Isopluvial Maps of Daily Maximum Precipitation for Different Frequency for Upper Cauvery Karnataka Mohammed Badiuddin Parvez1, Chalapathi k2,Amritha Thankachan3, M .Inayathulla4 1,2,3
Research Scholar, Department of Civil Engineering, UVCE, Bangalore University, Bangalore, Karnataka, India. 4 Professor, Department of Civil Engineering, UVCE, Bangalore University, Bangalore, Karnataka, India. Email: parvezuvce@gmail.com
ABSTRACT Probable maximum precipitation (PMP) is widely used by hydrologists for appraisal of probable maximum flood (PMF) used for soil and water conservation structures, and design of dam spillways. The estimation of design storm for example depends on availability of rainfall quantities and their durations. Daily maximum multiannual series are one of the main inputs for design streamflow calculation. The study generated annual series of Daily maximum rainfall for fourty four stations by using statical approach such as Normal distribution, Log-Normal Distribution, Pearson type III distribution and Gumbel’s Distribution .Results reveals that among the different statical approaches Log-Normal distribution fits the best compared to others. Isohyetal Maps of study area at different frequency are produced by using GIS tools, the maximum intensity varies from 2.5 mm/hr to 628 mm/hr. Key words: Climate change, Daily Maximum Rainfall, Gumbel’s distribution, Isopluvial Maps, Log-Normal Distribution, Maximum intensity, PMP, Rainfall Duration.
1 INTRODUCTION Water scarcity appears to be a future problem for Karnataka. This problem is an existential threat which can potentially hurt economic growth as well as agricultural growth. Water is expensive and inexpensive depending on its availability according to law of demand and supply. Rainfall as an environmental phenomenon is of immense importance to mankind. Hence the significance of studies to understand the rainfall process cannot be overemphasized. Floods, droughts, rainstorms, and high winds are extreme environmental events which have severe consequences on human society. Planning for these weather-related emergencies, design of engineering structures, reservoir management, pollution control, and insurance risk calculations, all rely on knowledge of the frequency of these extreme events The total rainfall and its intensity for a certain period of time are variable from year to another. The variation for depth of rainfall and its intensity depend on the climate type and the length of the studied period. It can be noted in arid and semi-arid areas, there is a significant change in the value of rain from time to another. Due to the significant variation in rainfall and its intensity in a consider time, the design and construction of storm water drainage systems and flood control systems are not depend only on the average of long-term rainfall records but on particular depths of precipitation that can be predicted for a certain probability or return period. These depths of rainfall can only be determined through a comprehensive analysis of a long time series of historical rainfall data. The historical rainfall data series are distinguished by medium and standard deviation, this information cannot be randomly used to predict the rainfall depths that can be estimated with a specific probability or return period for design and management of storm water drainage. Application of this technique to a data set can lead to misguiding results where the actual properties of the distribution are neglected. To avoid mistake, it is necessary to verify the integrity of the assumed distribution before estimating the design depths of the rainfall. There is a need for information of the extreme amounts of rainfall for various durations in the design of hydraulic structures and control storm runoff, such as dams and barriers, and conveyance structures etc.
Volume 8, Issue 10, 2019
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