Complete Introduction of Terrain characteristics with case studies of the world

1. Terrain Evaluation
The knowledge of terrain
1. Many resources inventories and developmental activities.
2. Identification of probable sites of soil erosion, landslides,floods and its prevention is
necessary to maintain soil productivity as well as to save life and property.
3. It is also relevant in the context of alignment studies (roads, railways,canals, drainage & water
supply pipe lines, power transmission lines etc.)
4. site selection studies (airports, harbours, dams, reservoirs, construction material etc.). The
subject of slope stability and construction material has been the concern of civil engineers.
5. Town planning and urban development, watershed development, wasteland development are
based on terrain evaluation. Terrain evaluation is the prerequisite for hazard and disaster
management.
Terrain Evaluation should form in itself a complete piece of terrain information for the current
work as well as for the future reference.
Applications: first consideration is for socio-economic requirements. Apart from this, from
engineering considerations, the terrain characteristics such as topography, type of soil cover,
geomorphology, and land use / land cover are most important to evaluate the terrain for various
alternatives. Terrain characteristics are important to soil scientist, geologist, foresters,geographers,
civil engineers, urban and regional planners and all those who need to evaluate the suitability of
terrain for various landuse.
CASE STUDIES: DUBAI ISLANDS :THE WORLD, Next Project is THE UNIVERSE
Considerations for Terrain Evaluation:
• Purpose : Additional land for development, recreation and tourism,
• Has to be located at tourist place of attraction, with other infrastructure
facilities for tourism as well as for residential and commercial applications
• Sandy areas,very deep bedrock , possibility of sea encroachment at other
places along the coast are problems.
• Challenges for reclamation, infrastructure development and building construction.
• Approachability for construction activities.
• Availability of construction material and expertise.
• Demand for development.
Building a Hanging Footpath
Considerations for Terrain Evaluation :
• Purpose : Sightseeing.
• Has to be located at tourist place, with other infrastructure facilities for tourism.
• In the ranges of mountain
• Very Good view for sightseeing
• Approachability at both ends
• Good solid rock
• Accessibility for construction
• Availability of specially skilled manpower
Hoover Dam :
Engineering Construction and Challenges ;
The top of the white band of rock in Lake is the old waterline, prior to the drought and development
in the Las Vegas area. It is over 100 feet above the current water level.
The original road joining New York to San Francisco was also opened in 1936. To avoid the
bottleneck along the long old road, twisting and winding around and across the dam
itself, 900 feet above the mighty Colorado River, a $160 million bridge was planned at the Hoover
Dam, known as the Hoover Dam bypass. It provides a new link between the states of

2. Nevada and Arizona. In an incredible feat of engineering, the road is supported on the two
massive concrete arches.
China’s RailwayAcross the Roofof the World:
Since the founding of the Republic of China in 1911, It has been China’s dream to have a national
railway system,connecting all provinces of the nation. Tibet became the last province to remain
unconnected owing to great and innumerable obstacles, since the 1950s. Among the many
challenges faced by Chinese railway planners, The following were the most significant:-
Formidable mountain barriers
Unstable permafrost & swampy wetlands
A Fragile Ecosystem
There were 17,000 ft-high mountains to climb, 12 kilometre-wide valleys to bridge,
Hundreds of kilometres of perennial ice and slush, that could never support tracks and trains.
How could anyone tunnel through rock at -400C, or lay rails when the least exertion sends you
gasping for oxygen in the thin air?
Kunlun Mountain Range: About 85 percent of the entire rail track is located in the ‘Forbidden
Zone’. This is also known as the “Death Zone” because of thin air, harsh and unpredictable
weather,fierce sandstorms and high UV radiation. Annual average temp is minus zero. Temperature
drops to as low as -45 degree C. Average altitude of rail track is 13,500 feet above sea level. The
highest point is 16,700 feet, making it the world's most elevated track.
Unstable Permafrost: There is a total of 550 km of permafrost along the rail route. Permafrost is
soft and wet soil in summer, hard and expanding in winter. - a nightmare for all railroad engineers.
The most viable solution is….Building of stone embankments for the railroad foundation.
In other spots, a pipe called a thermo-siphon was sunk 15 feet into the ground and filled at the bottom
with ammonia. The ammonia becomes gas at low temperatures,giving off a vapour that draws heat
from the bottom of the tube and flushes it out the top.
Konkan Railway
• Railway line running along the west coast of India. A missing link between India’s commercial
capital, Mumbai & Mangalore. 760 km line - 4850 hectares area • Built over most formidable western
ghats. Total Project spans across 30 years but actually constructed in 4 years
Technical challenges
-- Threat of heavy rainfall ; rainfall induced Landslides
-- Laterites and Lateritic Soft soils
-- Covering deep valleys, rugged moutains
-- Building state-of-the-art facilities
Considerations for TerrainEvaluation
- Identifying necessity of project
- Project Site Selection ( Railway Alignment)
- Land use planning
- Methodology of project
- Execution / Construction & maintenance
- Prioritization of work elements
- Project evaluation & EIA
- Future growth analysis
TERRAIN EVALUATION: site investigation as:
“Investigation of sites for the purpose of assessing their suitability for the construction of
civil engineering works, and of acquiring knowledge of the characteristics of a site, that
affect the design and construction of such works and securing of neighboring land and property.”
Terrain Evaluation has a much broader scope than this.
Terrain Evaluation implies the process ofassessment ofthe performance ofterrain when

3. it is used for specific purposes.
This involves the execution and interpretation of surveys and studies of landforms, soils, landcover,
vegetation, climate and other aspects of terrain; in order to identify and make a comparison of
promising kinds of landuse, in terms applicable to the objectives of the evaluation. The classification,
mapping and analysis provide a basic input in terrain evaluation studies.
Terrain classification involves the arrangement and grouping of the different areas of the earth’s
surface into a variety of categories on the basis of similarity of the type of surface and
near surface attributes. Terrain classification leads to terrain mapping. Each classified terrain facet is
further analyzed to understand its characteristic properties and behaviour in details. All these
combindly form the basis for terrain evaluation.
NECESSITYOF TERRAIN EVALUATION :
For the following activities ;-
Project Site Selection
Landuse Planning
Decide Methodology of Project
Construction / Erection
Execution and Maintenance
Developments and
Expansions
Prioritization of : work elements,
Areas of Development
Validation of : Data
Processes
models and Simulations
Methodology
Project Evaluation
Environmental Impact Assessment
QUANTITATIVE TERRAINDESCRIPTION:
Terrain can be described in qualitative or quantitative terms.
Qualitative Approach
Simple but Subjective Involves Visual inspection and Comparison of Maps, Photographs, Satellite
Imagery and Topographic Conditions
Quantitative Approach
Rigorous and Objective Involves Estimation of Parameters:Spectral-Textural Properties of Remote
Sensing Data; Terrain Elevations, Physical, Chemical and Engineering Characteristics of Terrain.
For appropriate terrain evaluation, the parameters to describe the terrain quantitatively, should be
chosen very carefully. The choice will depend on the type of the project area and the objective of the
terrain evaluation. The parameters chosen should satisfy following conditions
1. The parameter should be conceptually descriptive. i.e. should project mental image of physical
characteristic
2. The parameter should be easily measurable.
3. The parameter should be suitable for further numerical and statistical analysis
4. The parameter should allow objective comparison between two areas
The data collected is expressed in the form of maps and definitions of quantitative as well as
descriptive terms of the characteristic properties of each identified terrain feature. This is essential so
that the classification becomes workable in the hands of the user.
ADVANTAGES OF QUANTITATIVE APPROACH
- Offer mutually exclusive classification system in which classes are finite and do not overlap.
- Measure complex and functional relationships between the terrain units and their properties.
- Measure the variations in these properties within and between the engineering terrain units.
- Supply logical, simple, objective and organized basis for site investigation.
- Allow extrapolation of any characteristic of terrain.

4. - Facilitate integration of various data types and thus offer collectively exhaustive and all
inclusive terrain evaluation system.
- Facilitate computer aided objective approach
Terrain Evaluation Approaches can also be classified as :
ANALYTICAL METHODS
These are closed Form methods based on analysis of terrain parameters using Numerical
methods(finite elements, finite differences, boundary elements) or Analog simulations
using laboratory and in-situ testing and Theoretical Modelling.
EMPIRICAL DESIGN METHODS
In this approach statistical analysis of past events, processes is done and Empirical design
parameters,values, charts,nomograms are prepared for future use. Rock Mass Classification table is
the best example.
OBSERVATIONAL METHODS
These rely on actualmonitoring of Terrain Performance before-during-after the event or Process and
analyze them. Although considered as separate method, this is the only way to check the results and
predictions of both the above methods.
ADVANTAGES OF DEVELOPING GENNERALISEDTERRAIN CLASSIFICATION
SYSTEM
* Supplies more logical and organized basis for site investigation than the conventional methods
* Allows extrapolation of any characteristics of terrain
* Data gathered on one project can be useful in another project
* Facilitates integration of various data types, e.g. data collected by conventional method and

5. data generated from analysis of R.S. data
* Gives basis for the development of computerized Geographic Information System (GIS)
TERRAIN CLASSIFICATION SYSTEM
CRITERIA FOR STANDARD TERRAIN CLASSIFICATION SYSTEM
* Accuracy of terrain units mapped and the characteristics measured,should be above 85%
* Two different interpreters should be able to produce repeatable & repetitive results
* The classification system should be suitable to use with remotely sensed data obtained at
different times in a year
* Aggregation of categories should be possible
* Interpolation, extrapolation & generalization of categories should be easy
* Comparison with future landuse data must be possible
* Classification system should be able to help in multipurpose project evaluations
There are three main approaches of designing the terrain classification system. These are: a) the
Genetic Approach, b) the Landform Approach and c) the Parametric Approach.
In genetic approach, more attention is given to process of profile development. These result in a
classification system composed of terrain units, systems and provinces that can hardly be used in
the present context. It would be useful in academic research. The landform approach may serve the
purpose much better, particularly if it is based on the principles of geomorphology.
The parametric approach is also frequently too academic and tends not to contribute to a clear
understanding of the gross interactions involved in the development of phenomenal terrain feature.
Landform approach with limited parametric sampling is usually adopted for semi detailed and
detailed terrain evaluation. This can further be combined with the information about the geology
of the terrain, Geomorphological Approach. best out of all the three abovementioned approaches. This
is then referred as the This is amenable to Remote Sensing data also because it is reasoned that ‘the
areas of terrain having the same mode of origin and occupying the same position in the landscape,
would have similar surface materials.