Planning With Contours

AIM •

To understand understand the various concerns while planning plann ing with contours.

LIMITATIONs •

Calculation part is not discussed.

INTRODUCTION •

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An imaginar line that connects all points o! e"ual elevation a#ove or #elow a !i$ed re!erence plane or datum. In other words% contour is a line in which the ground sur!ace is intersected # a level sur!ace o#tained #  &oining points o! e"ual elevation. Contour line is a graphic representation o! a contour on a plan or map. The process o! tracing contour lines on the sur!ace o! earth is called contouring.

T'RMINOLO() •

*teep slopes + Contours are closel spaced.

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(entle slopes + Contours are less closel spaced .

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,ori-ontal '"uivalent  The hori-ontal distance #etween two consecutive contour lines .

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Contour Interval +The constant vertical distance #etween two consecutive contours is called the contour interval.

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Mean *ea Level + Average height o! the sur!ace o! sea !or all stages o! the tide.

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'levations + /ertical /ertical distance !rom the datum to the plane.

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Datum  It is a re!erence point !rom which all elevations are measured.

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,ILL A hill is a point or small area o! high ground. 0hen ou are on a hilltop% the ground slopes down in all

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directions. The height and slope o! a hill are represented on a map # the num#er o! concentric contour rings and

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the distance #etween the rings.

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RID(' A ridge is a line o! high ground with height variations along its crest. The contours along the sides o! the ridge will #e relativel parallel and there will #e several high points along the ridge. /ALL') A valle is an elongated depression that !orms the space #etween two ridges. /alle and ridges are interconnected. Ridge side slope create the valle walls.

*ADDL' A saddle is a dip or low point along the edge o! a ridge. A saddle is not necessaril the lower ground #etween two hilltops. It ma also #e a #rea1 along an otherwise level ridge . D'2R'**ION Depression is a low point or hole in the ground that is also surrounded on all sides # higher ground. Lowest contour at the centre. The map sm#ol that represents a depression is closed contour lines.

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CHARACTERISTIC All points in a contour line have the same elevation.  3lat ground is indicated where the contours are widel separated and steep+slope where the run close together. A series o! closed contour lines on the map represent a hill% i! the higher values are inside. A series o! closed contour lines on the map indicate a depression i! the higher values are outside. 0ater !lows perpendicular to contour lines. Contour line cross ridge or valle line at right an gles.

Contour lines cannot merge or cross one another on map e$cept in the case o! an overhanging cli!!. Contours cannot end anwhere #ut close on themselves either within or outside the limits o! the map.  Contour lines never run into one another e$cept in the case o! a vertical cli!!. In this case %several contours coincide and the hori-ontal e"uivalent #ecomes -ero.

SLOPE ANALYSIS It is a analsis o! the steepness o! the terrain. To determine the #est areas !or placing #uildings% roads% par1ing lots and other activities on a particular site. Used !or consideration such as economics% vegetation% drainage% soils etc. *lopes o! less than a#out 4 percent in the open landscape appear !lat to the human ee. In order to conduct a slope analsis on a map in!ormation re"uired is+ + ,ori-ontal scale + Contour interval + 2ercentage o! slope categories. + *cale and contour interval are esta#lished # the analsis.

GRADING •

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(rading is the process o! modi!ication o! e$isting land!orm to accommodate new structures% par1ing and circulation and to ensure positive drainage. The process o! developing grading plans involves manipulation o! three !actors5

+ (radient. 6(7 + ,ori-ontal distance. 6,7 + Di!!erence in elevation #etween two points. 6D7 ( 8 D9,

(RADIN( /OCA:ULAR) •

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Contour Line + A line made up o! points all e"ual in elevation (radient + The rate o! regular ascent or descent *wale + A depressed area o! land used to collect and direct sur!ace water runo!!  Cross+slope + The latitudinal pitch across an area to increase sur!ace drainage 'asement + Land owned # another which entitles the holder to speci!ic limited uses

*IT' (RADIN( T'C,NI;U'* Anal-e e$isting conditions o! the site5 (eneral !low o! water  '$isting !low lines !or sur!ace runo!!  '$isting structures% trees% etc. to #e saved *et preliminar elevations o! structures5  Anal-e e$isting elevations o! structures Chec1 elevations with ad&acent elements Chec1 relationships #etween #uildings% wal1s% par1ing lots% etc. Modi! appropriate contours5 :egin !rom 1nown points and calculate slope to ne$t contour  0or1 each contour line completel to #e sure to meet to e$isting Calculate re"uired slopes and modi! all other con tours as necessar •

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(RADIN( M'T,OD*