Reference No, GSI L5 I t7 4 / 05/Ots/GOA/HY/DFR /00 Tite Draft Final Report on Bathymetric and Topoqraphic Survey for De-srlting of Meghadrigedda Reservorr In Visakhapatnam District Andhra Pradesh. India Govt. of Andhra Pradesh Client Irragation & CAD Department 1.O INTRODUCTION 1.1 General Government of Andhra Pradesh, Department of Irrigation and Command Area Development (CAD) are planning to augment storage capacities with the catchment areas of reservoirs across the state of Andhra Pradesh. One such reservoir "Meghadrigedda Reservoir" located between Narava and Yerrakonda hills in the vicinity of district of Visakhapatnam was identified for de-silting in summer of 2015. Govt. of Andhra Pradesh contacted Dredging Corporation of India (DCI), Visakhapatnam for carrying out de-silting operations. DCI, after making site visits recommended bathymetric and topographic surveys to be carried out to estimate the siltation levels with the reservoir. The Meghadrigedda Reservoir Project was constructed across the river Naravagedda and Meghadrigedda at Kamarapalem village in Visakhapatnam District in the year f977, Th|e catchment area is about 368 sq.kms, which includes the reservoir. The reservoir was commissioned in the year 1979 with a storage capacity of 28 31 M.cum and later. during the year 1989, the water withdrawal capacity of the reservoir was increased to 10.00 million gallons per day (source: zilla PrajaParishad), with the reservoir capacity increased to 33.1024 M.cum @ F.R.L + 18.60 m. The maximum length of the reservoir is 2950 m and the maximum breadth is around 17OO m. with a total area of approx.5.015 sq km. unlike the reservoirs constructed in the hilly terrain, Meghadrigedda is a typical shallow reservoir covering a large area. Even a meter thickness of sediment deposit in the bed causes the reduction of huge quantity of water storage. Hydrogaphic survey conducted in 2011-2012 derived a reduced reservoir capacity to 22.A268 M.cum. The annual loss comes to 0.293 and the rate of siltation comes to 20.824 Ha.M/1OO Sq.km / Year. Taking into account the elapsed three years'time and the recent cylone "Hudh Hudh" in October 2014 it is envisaged that the storage capacity many have reduced further. Based on the above assumptions, Govt. of Andhra Pradesh, Department of lrrigation, contacted M/s Geosense surveys, visakhapatnam to conduct bathymetric and topographic survey with the reservoir limits and to estimate the present storage Capacity and loss due to siltation process. This report contains the bathymetric surveys details, the results and the computations carried out in the above areas of interest. Reference No, Rev Division Date Doc. Information Page 28" May. Hydrographic Page 7 of cs/1 5i 1 74l05/01 5/GOTJHY/DFR./00 00 Survey 2015 Survev 47 Reference No. GsI t5 I 17 4 / 05 /Ot5/GOA/HY/DFR/00 Ttle Draft Final Report on Bathymetric and Topographic Survey for De-silting of Meghadrigedda Reservoir ln visakhapatnam District Ahdhra Pradesh. India Govt, of Andhra Pradesh Client lrrigation & CAD Department 2.O SUMMARY OF RESULTS 2.L Bathymetry Odom Echotrac MKII, SyQwest Bathy DF 500 echo sounders and Pentax 325 EX Total Station was utilised to acquire bathymetric and topographic surveys within the Meghadrigedda reservoir basin. A value of 1480 m/s was used as the average velocity of sound in fresh water which was applied in the environmental setup during acquisition. The data so obtained was then processed using Hypack 6.2b and contouring was done using Hypackfferra Model software. Reservoir reference levels were taking early in the morning day to day for the entire period of survey. Bathymetry data as obtained from the Echo Sounder was corrected for heights of the reservoir reference level and reduced to Mean Sea Level (MSL). The dry patches/ inaccessible areas left over by the echo sounding were covered by topographic surveys. All the bathymetry and topographic data was resolved to 0.1 m and plotted on scales of 1 :5,000 & 1:2,000 The minimum and maximum depths/elevations observed from bathymetric and topographic surveys are 8.93 m and 22.92 m in the reservoir basin up to flood bank area. All the levels below 16.0151m (52.54 ft)(reservoir average water level) up to 13.4112 m (44 ft)have been considered for computation as "dredging quantities", whereas all the levels above 16.0151m and up to 2L.6048 (71 ft) which is the TBL have been considered for computation "excavation quantities". Reference No. Rev Division Date Doc. lnformation Page 28' May, Hydrographic Page 9 of GS/1 5/1 74105/01 5/GOA./HY/DFRv00 00 Survey 2015 Survev 47 Reference No. GS/ tsl 17 4 / osl0 1 s/GoA/HY/DFR/00 Title Draft Final Report on Bathymetric and Topographic Survey for De-silting of Meghadrigedda Reservoir In Visakhapatnam District Andhra Pradesh. India Govt. of Andhra Pradesh Client Irrigation & CAD Department t.2 Location Diagram Courtesy: Google Earth (Note: The below map is indicative and is not to scale) Figure 1: General Location diagram with survey lines marked in red Kindly refer to Appendix A for a detailed map of locations on Google Earth, please install GoogleEarthWin-6.1.0.5001.exe and double click Meghadrigedda.kmz to see the locations in Google earth program. (.exe and .kmz file given in Appendix A.) ..v Reference No. Rev Division Date Doc. Information Page 28'May, Hydrographic Page 8 of GS/1 5/1 74105/0 1 s/GOA/HY/DFR/00 00 Survey 2015 Srrrvev 47 Reference No. GS M I t7 4 / 05 / OL 5 / GOA"/HY/DFR/00 Title Draft Final Report on Bathymetric and Topographic Survey for De-silting ot Fleghadrigedda Reservoir ln Visakhapatnam District Andhra Pradesh, India Govt. of Andhra Pradesh Client Irrigation & CAD Department 4.O METHODOLOGY Geosense Surveys mobilized, install, interface, operate all survey systems and provide all required survey personnel undertake bathymetry survey services in the area of interest. The mobilization of the equipment was done on 16.05.2015 to carry out survey activities upon verbal confirmation from Irrigation & CAD department 4.L Area of Interest The area of interest is North west of visakhapatnam city at a distance of 22.5 km near Chinamushidivada Village. 4.1.1 Location of Rcservoir: The location of reservoir is bounded by the following co-ordinates LOCATION OF RESERVOIR WGS-84 Spheroid, UTM Proiection, CM 810 East, zone 44, North Location Easting (m) I{orthing (m) Latitude (N) Longitude (E) : Point A 7 328t9 .428 1964911.508 17045'33.30' 83011'45.09" Point B 732364 732 1964887.128 L7o4s'32.68" I !3:11?s.6r] Point C 731415.457 1964644.493 L7045'25.L5" 83010'57.34" Point D 73O44t.54O 1966680.782 L7o46,3!.73" : 83o 10'25.09" Point rs67602.326 17047'01.53" I Ar" ro'+o.gr' E il19t1?.Po I i Point F 731892.t14 L967L58.647 L7046'46.72" 83011'14.51' Point G 732r7A 47g 1966429,118 17046'22.89" L 83.11'23.94 Table 2 : Location of Reservoir Reference No. Rev Division Date Doc. Information Pag e 28'May, Hydrographic Page 12 of GS/1 5/174105/01 s/GOAJHY/DFR 00 00 Survey 2015 Survey 47 Reference No. GS / ts / L7 4 / Os / Ots / Go Al HY / DFR/00 Title Draft Final Report on Bathymetric and Topographic Survey for De-silting of Meghadrigedda Reservoir In Visakhapatnam District Andhra Pradesh, India Govt. of Andhra Pradesh Client Irrigation & CAD Department 7.5 Veftical Control The area of interest is a contained water body (reservoir) and not connected to the open sea. Hence the effects of tides to this water body are not applicable. The water depths obtained within the reservoir are REIATIVE water depths that can vary from day-to-Oay based on the elevation of the water surface. In order to normalize all depth measurements to an absolute reference, water depths must be subtracted from an established value for the elevation of the water surface at the time of the bathymetric survey. Vertical Control for the survey area was established by measuring the water levels from a fixed point on daily basis. This will ensure changing (except minor losses due to evapoiation) water levels during the period of survey are compensated. The average of the level recorded within the survey period is considered as reference level. It was expected that there will be significant drop in the reservoir levels during the opening of the sluice gates and care is taken to note the reservoir levels during these times. However, no such activity was observed during the survey period. MEGAHDRIGEDDA RESERVOIR REFERENCE LEVELS Sr. No Date of SurueY Reservoir Water Elevations (feet) (meters) 1 16.05.2015 52.7 16.06296 2 17.05.2015 52.6 16.03248 3 18.05.2015 52.6 16.03248 4 19.05.2015 52.5 16.00200 5 20.05.2015 52.5 16.00200 6 21.05.2015 52.5 16.00200 7 22.05.20t5 52.4 L5.97t52 Average 52.5424 16.O151 Table 11: Meghadrigedda Reservoir Reference Levels All soundings have been referred to Mean Sea level (MSL). Refer Appendix F for water levels & graphs. Reference No. Rev Division Date Doc, Information Page 28'May, Hydrographic Page 32 of GSt 1 5t 17 4105t 01 s/GOA/HY/DFR/00 00 Survey 2015 Survev 47 Reference No, GS/ 15 / D 4 / 05 / Ots / GOA'/HY/DFR/00 Trtle Draft Final Report on Bathymetric and Topographic Survey for De-silting of Meghadrigedda Reservoir In Visakhapatnam District Andhra Pradesh, India Govt. of Andhra Pradesh Client Irrigation & CAD DePartment 13.0 GENERAL DESCRIPTION OF SURVEY LOCATION Mehadrigedda is an east flowing non-perennial river taking its rise in the Eastern Ghats at Nandiko;da hill.