Dec. 2015 Available O

International Journal of Advanced Scientific and Technical Research Issue 5 volume 7, Nov. –Dec. 2015 Available online on http://www.rspublication.com/ijst/index.html ISSN 2249-9954 Computation of Yield based on Weighted Normal Monsoon Rainfall for Kundu Sub-Basin of Pennar Basin

R. Bhavani Associate Professor in Civil Engineering,

JNTUA College of Engineering, Anantapur. E’mail ID : rb h avani 77@ yahoo.com

ABSTRACT Kundu’ is one of the eight sub basins of Pennar basin having 8683 Sq. km of catchment area. Thirty four rain gauge stations located within and around the sub-basin are influencing the catchment area. Percentage areas of influence for various rain gauges were determined by drawing Theissen polygons for all the existing rain gauge stations. Normal monsoon rainfall values for all rain gauge stations were extracted from the Hand book of Statistics, 2013 published by the Chief Planning Offices of respective districts. Weighted normal monsoon rain fall for the entire Kundu sub-basin has been computed and founded to be 649.7 mm. The total yield available in the sub-basin has been estimated for the weighted normal monsoon rainfall using the Strange’s table. For the purpose of yield calculations, Kundu sub-basin catchment has been considered as 50% good and 50% average. The total yield in the sub-basin from the entire catchment area of 8683 Sq. km considering weighted normal monsoon rainfall of 649.7 mm has been estimated as 1053.25 M.Cum.

Key words: Basin, Sub-basin, Normal monsoon rainfall, Perpendicular bisectors, Rain gauge station, Thiessen polygon, Weighted area and Yield. Abbreviations : M.cft - Million cubic feet; M.Cum - Million Cubic Metres; mm - Milli metres; S. No - Serial number; Sq. mile - Square mile; Sq. km - Square kilometer.

Corresponding Author: R. Bhavani

INTRODUCTION The term ‘yield’ in hydrological notation is the total quantity of water that may accumulate at the required location of a natural stream/river course during a particular period, generally monthly or annually. Basic requirement to design any hydrological structure is the estimation of yield based on rainfall data. Rainfall data is measured at certain locations called rain gauge stations and is expressed in terms of depth. Rainfall can be expressed in different ways as annual rainfall, normal rainfall and normal annual rainfall. Annual rainfall is the total rainfall received during a particular year for a particular rain gauge station. "Normal rainfall” for a particular rain gauge station is an average of 30 years rainfall. Monsoon rainfall is the rainfall received during monsoon period for a particular rain gauge station. Normal Monsoon rainfall for a particular rain gauge station is an average of 30 years monsoon rainfall. When a catchment area is influenced by more than one rain gauge station, the weighted rainfall for the entire

International Journal of Advanced Scientific and Technical Research Issue 5 volume 7, Nov. –Dec. 2015 Available online on http://www.rspublication.com/ijst/index.html ISSN 2249-9954

catchment area is to be calculated. To compute the weighted rainfall, three methods namely arithmetic mean method, Theissen polygon method and isohyetal methods are available among which Theissen polygon method has been considered for the present study. STUDY AREA River Pennar originates at Nandi Hills near Chikkabalapura, Karnataka and flows for about 48 Km in Karnataka and enters Andhra Pradesh near Chouluru, Hindupur mandal of Anantapur district. After flowing for a total distance of 597 km, the river joins Bay of Bengal near Vutukuru village at about 30km north east of Nellore town. The entire Pennar basin has its spread mostly in 5 districts namely Anantapur, Kurnool, Kadapa, Chittoor and Nellore districts of Andhra Pradesh. Pennar river basin has eight sub-basins namely 1. Upper Pennar 2.Middle (Mid) Pennar 3.Chitravathi 4.Kundu 5.Papagni 6.Sagileru 7.Cheyyeru and 8. Lower Pennar. Kundu sub-basin which is the largest among all these, has been selected for the present study. It originates at Nallamala hill range at about 12 km east of Pasurutla village, Atmakur Mandal, Kurnool district, Andhra Pradesh, India. It flows mostly in Kurnool district and enters in Kadapa district before it confluences with river Pennar near Eturu village, Khajipeta mandal, Kadapa district. An Index map showing the study area is given in figure 1.

Fig 1: Index Map showing the study area DATA Following data has been collected for the present study (i) Rain gauge stations existing within and around the sub-basin have been identified based on Topo sheets with numbers 57E, 57I and 57J of scale 1:2,50,000.

International Journal of Advanced Scientific and Technical Research Issue 5 volume 7, Nov. –Dec. 2015 Available online on http://www.rspublication.com/ijst/index.html ISSN 2249-9954

(ii) Normal monsoon rain fall particulars of influencing rain gage stations have been extracted from the Hand books of Statistics, 2013 published by the Chief Planning Offices of respective districts i.e. Kurnool, Kadapa and Anantapur districts. (iii) Strange’s Yield table has been extracted from Irrigation manual by W.M. Ellis for estimation of total yield.

METHODOLOGY Based on topo sheets, a digitized map showing all the natural stream courses with in Kundu river basin has been developed using ‘AutoCAD’. In Auto CAD, boundary of the basin has been traced out based on the origin of stream courses and area covered by the basin has been computed as 8683 Sq.km. A map showing the existing natural stream courses and boundary of the basin has been presented in figure 2.

Fig 2 : Kundu sub-basin with natural stream courses

International Journal of Advanced Scientific and Technical Research Issue 5 volume 7, Nov. –Dec. 2015 Available online on http://www.rspublication.com/ijst/index.html ISSN 2249-9954

Rain gauge stations influencing the entire sub-basin have been determined by ‘Theissen polygon’ method. Procedure for construction of Theissen polygons is as follows. Locations of 34 rain gauge stations located in and around the sub-basin were identified on plan and lines connecting the adjacent stations were drawn. Perpendicular bisectors were developed for all the lines joining the rain gauge stations and were extended to form the polygon around each rain gauge station. A map showing the locations of rain gauge stations and the construction lines for Theissen polygons is given in figure 3.

Fig 3 : Map showing the Influencing zones of rain gauge stations for Kundu Sub-basin

International Journal of Advanced Scientific and Technical Research Issue 5 volume 7, Nov. –Dec. 2015 Available online on http://www.rspublication.com/ijst/index.html ISSN 2249-9954

From figure 3, influencing area of each rain gauge station has been computed in Auto CAD and the corresponding percentage area in the total basin area has been calculated. The details were presented in table 1.

Table 1. Details of percentage influence of rain gauge stations for Kundu sub-basin

% area % area Influencing Name of the Influencing S Name of rain Influence S Influence area rain gauge area No gauge station in total No. in total . (Sq. km) station (Sq. km) area area Rain gauge stations located in Kurnool 19 Rudravaram 472.050 5.437 district 1 Vorvakallu 349.040 4.020 20 Allagadda 260.190 2.997 2 Miduthuru 107.120 1.234 21 Uyyalawada 374.400 4.312 3 Pamulapadu 71.380 0.822 22 Sanjamala 185.240 2.133 4 Atmakur 88.630 1.021 23 Koilakuntla 177.960 2.050 5 Velugodu 466.410 5.372 24 Chagalamarri 568.670 6.549 6 Gadivemula 302.280 3.481 25 Kolimigundla 482.100 5.552 7 Veldurthi 3.000 0.035 26 Peapally 40.520 0.467 Betham- 27 Dornipadu 172.140 1.983 8 cherla 485.840 5.595 9 Panyam 341.420 3.932 Rain gauge stations located in Kadapa District 10 Nandyal 212.340 2.445 1 Duvvuru 411.320 4.737 11 Bandi 256.740 2.957 2 Mydukuru 130.650 1.505 Atmakuru 12 Mahanandi 576.050 6.634 3 Kamalpuram 20.300 0.234 13 Sirvel 219.160 2.524 4 Proddatur 162.280 1.869 14 Gospadu 213.640 2.460 5 Jammala- 378.360 4.358 madugu 15 Nandavaram 188.930 2.176 Rain gauge stations located in Anantapur District 16 Banagana - 206.040 2.373 1 Tadipatri 27.730 0.319 palli 17 Owk 489.850 5.642 2 Yadiki 36.040 0.415 18 Dhone 204.890 2.360 Total : 8682.710 100.000 Say 8683.0

The details of normal monsoon rain fall for all influencing rain gauge stations of Kundu sub- basin extracted from the Hand book of Statistics, 2013 published by the Chief Planning Offices of respective districts, were presented in table 2. Also normal weighted rainfall has been computed for all rain gauge stations and presented in table 2.

International Journal of Advanced Scientific and Technical Research Issue 5 volume 7, Nov. –Dec. 2015 Available online on http://www.rspublication.com/ijst/index.html ISSN 2249-9954

Table 2. Details of normal monsoon rain fall for all rain gauge stations of Kundu Sub-basin % area Normal monsoon rainfall in mm S Name of the rain influence Total weighted June to October to No. gauge station in total monsoon rain fall in September December area rain fall mm 1 Vorvakallu 4.020 361.5 144.0 505.5 20.3 2 Miduthuru 1.234 496.8 143.5 640.3 7.9 3 Pamulapadu 0.822 538.9 116.4 655.3 5.4 4 Atmakur 1.021 551.5 165.8 717.3 7.3 5 Velugodu 5.372 570.5 161.8 732.3 39.3 6 Gadivemula 3.481 486.2 140.3 626.5 21.8 7 Veldurthi 0.035 386.8 138.5 525.3 0.2 8 Bethamcherla 5.595 392.0 171.6 563.6 31.5 9 Panyam 3.932 456.2 136.9 593.1 23.3 10 Nandyal 2.445 592.2 156.7 748.9 18.3 11 Bandi Atmakuru 2.957 589.4 163.5 752.9 22.3 12 Mahanandi 6.634 577.1 158.7 735.8 48.8 13 Sirvel 2.524 597.5 148.5 746.0 18.8 14 Gospadu 2.460 530.8 152.0 682.8 16.8 15 Nandavaram 2.176 368.1 156.9 525.0 11.4 16 Banaganapalli 2.373 407.8 150.8 558.6 13.3 17 Owk 5.642 359.1 152.2 511.3 28.8 18 Dhone 2.360 350.9 129.7 480.6 11.3 19 Rudravaram 5.437 673.6 172.6 846.2 46.0 20 Allagadda 2.997 544.4 175.7 720.1 21.6 21 Uyyalawada 4.312 510.4 154.8 665.2 28.7 22 Sanjamala 2.133 454.7 146.7 601.4 12.8 23 Koilakuntla 2.050 479.0 167.1 646.1 13.2 24 Chagalamarri 6.549 558.1 188.8 746.9 48.9 25 Kolimigundla 5.552 423.2 156.5 579.7 32.2 26 Peapally 0.467 430.4 153.1 583.5 2.7 27 Dornipadu 1.983 484.7 132.5 617.2 12.2 28 Duvvuru 4.737 467.6 193.6 661.2 31.3 29 Mydukuru 1.505 441.9 205.9 647.8 9.7 30 Kamalpuram 0.234 409.8 194.9 604.7 1.4 31 Proddatur 1.869 410.2 183.6 593.8 11.1 32 Jammalamadugu 4.358 439.1 171.0 610.1 26.6 33 Tadipatri 0.319 435.6 183.3 618.9 2.0 34 Yadiki 0.415 432.0 169.0 601.0 2.5 Total : 100.000 649.7

From table 2, weighted normal monsoon rain fall for the entire Kundu sub-basin is 649.7 mm (25.6 Inches). Total yield available in the sub-basin has been estimated for the weighted normal monsoon rainfall using Strange’s table. Based on the terrain observed from toposheets, catchment area of Kundu sub-basin has been considered as 50% good and 50% average for the purpose of yield calculations.

International Journal of Advanced Scientific and Technical Research Issue 5 volume 7, Nov. –Dec. 2015 Available online on http://www.rspublication.com/ijst/index.html ISSN 2249-9954

Yield for 25 and 26 Inches rainfall is 11.964 and 13.168 M.cft/ Sq. mile respectively for good catchment area from Strange’s table. The interpolated value of yield for 25.6 Inches rainfall is 12.686 M.cft/ Sq. mile. Yield for 25 and 26 Inches rainfall is 8.973 and 9.876 M.cft/ Sq. mile respectively for average catchment area. The interpolated value of yield for 25.6 Inches rainfall is 9.515 M.cft/ Sq. mile. Average value of yield per sq. mile = (12.686 + 9.515)/2 = 11.100 M.cft. = 0.314 M.Cum Average value of yield per sq. km = 0.314/(1.609 x 1.609) = 0.1213 M.Cum Total yield available in Kundu sub-basin with catchment area of 8683 Sq. km considering Normal monsoon rainfall = 0.1213 x 8683 = 1053.25 M.Cum. RESULTS For computation of weighted rainfall 34 number of rain gauge stations influencing Kundu sub-basin have been considered. Based on the percentage influence of each rain gauge station, the weighted normal monsoon rainfall has been computed as 649.7 mm. The classification of catchment area has been considered as a combination of 50% good and 50% average for the purpose of yield calculations. The total yield available in Kundu sub- basin with catchment area of 8683 Sq. km considering normal monsoon rainfall of 649.7 mm has been estimated as 1053.25 M.Cum. REFERENCES [1] COL. W. M. Ellis, College of Engineering Manual for Iirrigation printed by the Superintendent Government Press, Madras 1950. [2] P. Jaya Rami Reddy, A textbook of Hydrology, 2nd edition, Laxmi publications (P) LTD, New Delhi. [3] K. Subramanya, Engineering Hydrology, 3rd edition, The McGraw-Hill Publishing Company Ltd, New Delhi. [4] R. Bhavani, Construction of Theissen Polygons for Rain Gauge Stations in Anantapuram District, International Journal of Computational Engineering Research Vol. 03, Issue 6, June, 2013. [5] Hand book of Statistics, Ananthapuramu district 2013 by Chief Planning Officer, Ananthapuramu. [6] Hand book of Statistics, Kadapa district 2013 by Chief Planning Officer, Kadapa. [7] Hand book of Statistics, Kurnool district 2014 by Chief Planning Officer, Kurnool. [8] Managing Drought Risk on the Ranch, The National Drought Mitigation Center, 3310 Holdrege Street, Lincoln.