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Guidelines for DGPS/ETS Survey of Forest Area proposed to be diverted

Ministry of Environment and Forests, Govt. of India vide their circular No.F.No.-11-9/98-F , dated!8-!"-#!11 have sti$ulated that to ensure accurate delineation of forest area $ro$osed to %ediverted for non-forestry $ur$oses under &ection-# of Forest onservation 'ct, 198! the diversion$ro$osal under Forest onservation 'ct shall %e accom$anied %y (G)&/E*& surveyed ma$s of theforest land $ro$osed for diversion. *he &tate Govt. in Forest + Environment (e$artment havereco ni ed vide letter no.18 9 /F+E, dt.1 -1!-#!110 2&' as the nodal a ency to technicallyvet the (G)&/E*& surveyed ma$s underta3en %y user a encies. *o facilitate 4uic3 scrutiny at

2&' level, it is felt necessary to issue technical uidelines for the uidance of user a encies5hile underta3in (G)& survey. 'ccordin ly, the follo5in uidelines are issued.

DGPS/ETS Survey Guidelines 6(G)& survey is underta3en in t5o methods7 2eal *ime inetic mode and 2a$id &tatic mode. In%oth the methods, $rimary control $oints ) )s0 are re4uired to %e set u$ %efore ta3in u$ detailedsurvey on all $illar $ositions that com$ose the forest area.

a. Establishment of Primary Control Points ( ase Stations!" *he e tent of forest area and method of survey determine the no. of $rimary control $oints to %eesta%lished. In 2* method of survey, the distance of any $illar $osition should not %e more than 3m from the nearest $rimary control $oint. *hus no. of $rimary control $oints to %e set u$ 5ill haveto %e decided on the a%ove criteria su%:ect to a minimum of # $ointsIn the static mode of o%servation t5o $rimary control $oints are re4uired to %e esta%lished.*he $rimary control $oints are to %e monumented as $er the desi n and s$ecification attached tothis document.

b. #o$ation of Primary Control Points")rimary ontrol )oints are conce$tually $ermanent in nature and accordin ly its location is anim$ortant consideration to ensure that these $oints are not distur%ed in future. *he o$tion of locatinit in the near%y school or office $remises should %e e $lored other5ise the user a ency mustunderta3e to $rotect + $reserve these $oints 5hen $ro:ect is im$lemented.

$. Geo%$oordinates of ase Station"

Geo-coordinates of ;ase &tations ) )s0 are to %e determined %y 5ay of transfer from t5o 3no5n$oints throu h static mode of simultaneous and uninterru$ted o%servation in trian ulation method.*he o%servation shall %e for a minimum duration of < hours if the 3no5n $oints are 5ithin a distance

of =! M or 8 hours for distance 5ithin the ran e of =! to #!! M. 2&' 5ill facilitate $rovision of3no5n $oints.

d. Geo%$oordinates of other pillar positions"

*he eo-coordinates of other $illar $ositions & )s0 may %e determined throu h 2* mode ofo%servations, occu$yin the %ase stations so esta%lished. In case of &tatic Mode of %servation,

eo-coordinates of $illar $ositions may %e determined throu h trian ulation method 5ith a minimum1= minutes of o%servation on each $illar. If any $illar $osition is under cro5n cover, transmissionline, micro-5ave to5er etc. the eo-coordinates of such $illar $osition is to %e determined throu hinte rated E*&.

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e. Pro$essin& of 'a Data.

*he ra5 data of static mode of o%servation are to %e do5nloaded in to a com$uter and $ost-$rocessed to calculate the ( %aseline vector com$onents.

f. E)uipments

(ual fre4uency (G)& e4ui$ments are to %e used for all static mode of o%servation. Inte rated E*&e4ui$ment should %e used 5herever E*& survey is to %e underta3en.

&. Datum * Pro+e$tion System.

'll (G)& o%servation should %e made on the >G&-8< (atum and in ?*M $ro:ection system.

h. ,bservation &uidelines.

i0 In static mode of o%servation, trian le of o%servation should %e an acute an led trian le.

ii0 )oint of o%servation should %e o$en to s3y. *he s3y should %e clear u$ to 1= de ree cut-offan le. *here should not %e any to5er, transmission line, etc. near%y.iii0 *hreshold values of )( )/@( ) for each o%servation should not e ceed A.iv0 Minimum e$och of interval time should not %e more than 1= seconds.

i. Deliverable to ,'SAC.

'. (G)& o%servation static mode0i. 2a5 data and 2ine format data of all (G)& o%servations.ii. )ost B$rocessed values in Geo ra$hic co-ordinate &ystem and ?*M $ro:ection system.iii. )hoto ra$hs of all ) )s 5ith a %rief note on location.iv. )illar $oints indicated on the hard co$y of the ma$.

v. Net5or3 ad:ustment re$ort, if any.vi. 'ccuracy of the e4ui$ment.

. DGPS observation ('T- mode!

i. Geo-coordinates of & )s alon 5ith machine :o% file.ii. 'ccuracy of the e4ui$ment.

+. ETS observation"E*& can %e used to determine eo-coordinates of secondary control $oints. In case of surveythrou h E*&, the e4ui$ment shall have to %e oriented 5ith res$ect t5o near%y ) )s, notmore than =!! meters a$art, and then other $illar $ositions can %e o%served %y e tension$rinci$le. @o5ever such e tension shall not %e cumulatively %eyond 1 M and must close on a) ) at every 1 M of e tension.(elivera%le in case of E*& &urvey6

i0 2a5 data Co% file0ii0 Geo- co-ordinates of t5o $oints determined %y (G)& and used for E*& o%servation

iii0 'ccuracy of the e4ui$ment

If any user a ency has $rocured hi h resolution satellite data artosat-#, >orldvie5-1, >orldvie5-#, Duic3;ird, Geo-Eye0 for its lease area, then eo-rectification of satellite data 5ill %e done %y

2&' for 5hich the user a ency shall %ear the cost.

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