Index Contour Interval
What is Contour Interval?
A contour interval in surveying is the vertical distance or the distinction in the elevation between the two contour strains in a topographical map. Usually there are specific contour intervals for the specific maps. Considering the measurement of the vicinity to be mapped, contour intervals are assumed. In each and every map, on the right-hand backside side, the contour interval is specified. When the contour interval is no longer targeted in the map, it can be calculated as defined in the following sections. The often used contour interval is 20 toes for a 1:24,000 map scale.
Index Contour Interval
A contour line proven on a map in a distinct manner for ease of identification, being printed extra closely than different contour strains and normally labeled with a price (such as parent of elevation) alongside its course. It seems at ordinary intervals, such as each fifth or from time to time each fourth contour line (depending on the contour interval).
Uses of Contour in Surveying
The makes use of of contour in surveying are as follows:
- It suggests the slope and dimension of a number of landforms on the map.
- It offers a full and clear photo of the land and the surrounding area.
- With the assist of contour intervals it is handy to discover out the extraordinary elevations of the landscape.
- It offers the foundation for the coloring method.
Also Read: What Is Dry Pack Mortar
Calculation Of Contour Interval
These index strains will be mentioned with their elevation. Discover the elevations of two adjoining index lines. The largest range shows the uphill rise. Locate the distinction between the two elevations.
A contour map carries contour strains of a given geographical region. To keep the contour map convenient and comprehensible to read, no longer each contour line is marked with its elevation reading.
These marked or tagged strains are remembered or termed index contour Lines. In the above picture, the darkish strains with analyzing are index contour lines.
Factor Affecting Contour Interval
1. The Scale of The Map
The contour interval is inversely proportional to the scale of the map. If the scale is small, the contour interval ought to be massive and vice versa.
2. Nature of The Ground
The established terrain of the place determines the contour interval. For a flat area, the contour interval ought to be small. For sloping or undulating terrain, the chosen contour interval have to be large.
3. Purpose and Expansion of the survey work
If surveying work is to be used for specific and distinct calculations, then the small contour interval must be chosen and a giant contour interval is chosen for the following cases:
- For catchment areas
- To the reservoir
- For place survey
4. Time accessible and Eligible Expenses for area and workplace work
A massive contour interval ought to be used if the time accessible for survey work is less. The small contour interval, survey work and plotting need to be extra precise. For a small contour interval, the cash wished will additionally be extra as the area and workplace work will be larger.
Also Read: Traffic Rotary
Advantages of Contour Interval
- It suggests the slope and measurement of distinctive landforms on the map.
- By searching at the contour intervals it is convenient to calculate the a variety of elevations of the landscape.
- It can be utilized in drawing cross-sections of the particular points on the mapped area.
Disadvantages of Contour Interval
- Contour fail to signify a few of the heights due to the quandary of the vertical interval.
- Some of the landforms can't be represented by means of using contours. For instance coral reef, outcrop rock, and craters.
- The contour approach is no longer utilized to characterize alleviation on a small-scale map as it might also doubtful a few details.
Rules of Contour Intervals
- Every factor of a contour line has a comparable elevation.
- Contour traces awesome uphill from downhill.
- Contour traces by no means contact or go every different than at a cliff.
- Every fifth contour line is darker in colour than different contour lines. This is an INDEX contour line.
- Contour traces are nearer collectively in steep terrain and farther aside in flat areas.
Also Read: Concept Sketch Definition