IJSRD - International Journal for Scientific Research & Development| Vol. 5, Issue 02, 2017 | ISSN (online): 2321-0613 PMP Estimates for Kalpasar Project in Gulf of Khambhat (India) Dr. Surinder Kaur1 P. K. Gupta2 1Assistant Professor 2Student 1,2India Meteorological Department, New Delhi-110003, India Abstract— Gulf of Khambat is an inlet of the Arabian Sea fresh water reservoir in the sea and may be used for irrigation along the west coast of India, in the state of Gujarat. Gujarat and drinking water for Gujarat specially Saurashtra region. is a water deficit state specially the Saurashra region which is The Gulf of Khambhat extends from north to south rocky and barren. The annual per capita water availability is about 200 km and the width varies from 25 km at the inner 540 cubic meter in Saurashtra region which is much below end to 150 km at the outer mouth, covering an area of 17000 the minimum requirement of 1700 cubic meter. To store sq.km, of which only 2000 sq. km will be enclosed by surplus/untapped surface water, the Govt. of Gujarat proposes constructing a dam across the Gulf between Bhavnagar and construction of Kalpasar project in the Gulf of Khambhat Dahej. For the construction of a dam, the design storm which is an eligible option that can store fresh water of the estimates are required to compute the design flood. rivers of Dhadhar, Mahi, Sabarmati from one side and some Bhatt et.al. (2014) have generated Intensity duration of the Saurashtra rivers from the other side. This will be the frequency analysis for different return periods for Bhadar world’s largest man made fresh water reservoir in the sea. For Dam in Gujarat. Ramaswamy, c (1987) studied the construction of reservoir, the design storm estimates are catastrophic floods in the Sabarmati, Mahi and contiguous required for computation of design flood. In this paper, the rivers in July 1924. In WMO No.1045 (2009), the method of design storm estimates in the form of Probable Maximum computation of design storm estimates are described in detail. Precipitation (PMP) estimates have been computed for the In this paper, the design estimates in the form of Probable Kalpasar project in the Gulf of Khambhat. Maximum Precipitation (PMP) for Kalpasar project in the Key words: Gulf of Khambhat, Kalpasar, SPS, PMP Gulf of Khambhat covering the river basins of Sabarmati, Mahi, Dhadhar and some of Saurashtra Region are computed I. INTRODUCTION by following WMO criteria. Gujarat is the western-most state in India which occupies the northern extremity of the western sea-board of India. It lies II. DATA USED between latitude 20º07' and 24º43' N and longitude 68º10' and The daily rainfall data of about 200 stations in and around 74º29' E. The state is bounded by Pakistan in the north-west these catchment areas for the available period from 1901 to and the state of Rajasthan in north. To the east it borders 2012 have been used for the selection and analysis of heavy Madhya Pradesh, and Maharashtra. The Union Territories of rainstorm. The hourly rainfall data of 4 self-recording Daman, Diu, Dadra and Nagar Haveli lie to the south of raingauge stations have been used for the preparation of time Gujarat. It has 1600 km long coast line by the Arabian Sea distribution curves. The dew point temperature data of 3 forming the western and south-western boundary. Gujarat is stations namely, Ahmedabad, Porbandar and Rajkot have a water deficient State. The annual rainfall in the state varies been used for the computation of Moisture Adjustment Factor significantly. The mean annual rainfall ranges between 300 (MAF). Maximum persistent dew point temperature of these mm to 2800 mm. Normal rainfall of the state is 720.6 mm. stations have been taken from the IMD (2000) met The normal rainfall of Gujarat region is 1107mm and of monograph on “Generalized maps of 1-day point maximum Saurashtra and Kutch is 578mm. The state has 6.4 % of land persisting dew point temperature”. area of the country and 5% of the country's human population, but its surface water resource is only 2% of the country. The III. METHODOLOGY annual per capita water availability is 990 cubic meter in the The design estimates are given in the form of Standard State which is much below the minimum requirement of 1700 Project Storm (SPS) and Probable Maximum Precipitation cubic meter. However, even after (PMP) estimates for 1-day, 2-day and 3-Day duration and including Sardar Sarovar Project (SSP), only 20480 million temporal Distribution (TD) of 24 hr and 48 hr rainstorms. cubic meters (54%) is possible to store. There is no suitable Generally the term storm is used for rainstorm. site of land in the State available for the creation of river valley project to store surplus / untapped above 40% surface A. SPS and PMP water. In such a circumstance, the Govt. of Gujarat proposes The SPS is defined as the historical rainstorm that is the to create a reservoir by construction of a Gulf closure dam in heaviest rainstorm so far on record that has actually occurred Gulf of Khambhat which is an eligible option to store about over or near the basin under study. This storm can be 10,000 million cubic meter water inflows of the rivers considered to be reasonably characteristic of the region in ( Dhadhar, Mahi, Sabarmati and some of the Saurashtra), which the basin is located. The PMP is defined as the greatest which accounts for 25% of total surface water resources of depth of precipitation for a given duration meteorologically Gujarat. Creation of this fresh water reservoir does not possible for a design watershed or a given storm area at a involve any land acquisition or rehabilitation of people, and particular location at a particular time of year, with no will serve as a life line of the Saurashtra region as well as an allowance made for long-term climatic trends (WMO, 2009). accelerator for the growing economic activities Few heaviest rainstorms over or near the study area of Gujarat State. This will be the world’s largest man made have been selected and processed for SPS estimation which involves computation of Depth Area Duration (DAD), Depth All rights reserved by www.ijsrd.com 94 PMP Estimates for Kalpasar Project in Gulf of Khambhat (India) (IJSRD/Vol. 5/Issue 02/2017/026) Duration (DD), transposed depths, temporal and areal IV. RESULTS AND DISCUSSIONS distributions. These are used for the evaluation of SPS. The Moisture Adjustment Factor (MAF) is applied to SPS for estimation of PMP. MAF is the ratio of highest liquid water content recorded during rainstorm season near the centre of rainstorm to the persistent liquid water content recorded during rainstorm period. Liquid water content is estimated from surface dew point temperature at 1000 hPa assuming that environment is fully saturated and follows pseudo- adiabatic lapse rate. PMP = MAF * SPS B. Temporal Distribution of Storm Rainfall The spatial distribution of storm rainfall provides an idea about volume of water precipitated during a rainstorm. The temporal distribution of storm rainfall highlights intensity of rainfall experienced during different times of rainstorm duration. The highest intensity of rainfall decides the time of occurrence of peak flood, magnitude of peak discharge and consequently water level rising in river or stream. Fig. 1: Location and catchment area of Kalpasar Project. The temporal distribution is computed from hourly The catchment area for the Kalpasar project in the Gulf rainfall data of self-recording raingauge stations in and of Khambhat covering the river basins of Sabarmati, Mahi, around the catchment. The rainstorms are selected for Dhadhar and some of Saurashtra Region is shown in Figure different duration i.e. 24-hours and 48-hours. From these 1. rainstorms highest rainfall recorded during intermediate It also indicates the location of Kalpasar lake and the duration like continuous 3hr. .., 6hr..........., 24hr............., and system boundary of the river catchments. The design storm 48hr duration are worked out. These rain depths are expressed estimates are given in form of SPS, PMP and Temporal as percentage of total rainfall occurred during the storm and distribution. The SPS and PMP values are given for the area plotted against the respective duration. The percentage of System Boundary covering areas of Sabarmati, Mahi, values are suitably filled with smooth curve in each case. Dhadhar, for entire catchment areas of Sabarmati, Mahi, From these curves average temporal distribution is Dhadhar and some of river basins in Saurashtra region. The derived. Such analysis is done for each selected rainstorm for rainfall contributions of SPS are also given sub-catchments every SRRG station available in and around the catchment. wise for the river basins within System Boundary and for the Entire catchment. The rainstorms of 1, 2 and 3-days are selected using the historical daily rainfall data from 1901 to 2012. The stations reported highest ever recorded rainfall (≥ 200 mm) is given in the Table 1. The following severe most rainstorms were considered for carrying out further analysis. 1) 26-28July 1927 (centre at Dakor) 2) 20-22June 1983 (Centre at Upleta) 3) 23- 25July 1905 (Centre at Radhanpur) S.No. Catchment District Station Lat. Long. Data Period (years) Rainfall (mm) Date 1 Mahi Banswara Banswara 23.55 74.45 110 559 23/07/1959 2 Mahi Dungarpur Pderdi 23.75 74.12 27 512 26/08/1987 3 Mahi Banswara Garhi 23.60 74.13 99 490 9/7/2007 4 Mahi Dungarpur Dungarpur 23.85 73.72 108 486 30/06/1937 5 Mahi Panch-Mahals Halol 22.50 73.48 98 485 24/09/1945 6 Mahi Dohad Santrampur 23.18 73.87 65 465 29/07/1950 7 Mahi Baroda Baroda 22.33 73.27 83 460 24/09/1945 8 Mahi Anand Bhadran 22.37 72.90 53 451 23/09/1945 9 Mahi Panch-Mahals Kalol 22.62 73.47 100 440 24/08/1990 All rights reserved by www.ijsrd.com 95 PMP Estimates for Kalpasar Project in Gulf of Khambhat (India) (IJSRD/Vol.