APPLICATION OF REMOTE SENSING AND GIS IN CIVIL ENGINEERING
Sandeepan Saha* Civil Engineering Department Meghnad Saha Institute of Technology (WBUT)
Abstract
Remote Sensing and GIS techniques become potent potential ial and indisp indispens ensabl able e tools tools for solvin solving g many many prob proble lems ms of civi civill engi engine neer erin ing g and and terr terrai ain. n. Re Remo mote te sens ensing ing obser bserva vati tio ons pro provide vides s data ata on ea earrth’s th’s resour resources ces in a spati spatial al format format,, GIS co-rel co-relate ates s different kinds of spatial data and their attribute data, so as to use them in various fields of civil engineering. Different themes namely, terrain, geology, hydrology drainage, land use and so on can be extracted from remote sensing data. All the above thematic info inforrmat mation ion alo along with ith thei theirr attr attrib ibut utes es can can be integrated to solve many problems of civil engine engineeri ering. ng. Some Some curren currentt uses uses of GIS and Remote Remote Sensing in civil projects are housing, sanitation, power, wate waterr supp supply ly,, disp dispos osal al of effl efflue uent nts, s, urba urban n grow growth th,, irri irriga gati tion on proj projec ectt desi design gn and and plan planni ning ng,, new new road road alignment etc. For this Remote sensing and GIS are used to generate development models by integrating the inform informatio ation n on natura naturall resour resources ces,, demogr demograph aphic ic and socio ocio -eco -econo nom mic data ata in a GIS domain main with ith sate satell llit ite e data data.. Land Landsl slid ides es in moun mounta tain inou ous s area areas s causing heavy loss can also be mapped and landslide prone zones can also be delineated. Deve Develo lopm pmen entt of hydr hydrop opow ower er site sites s and and irri irriga gati tion on project can also be formulated by integrating terrain (DEM) and thematic maps (land use, geology, DEM). All these can be derived from high resolution stereo pair of remote sensing data. These techniques are also useful in rehabilitation also. Other uses are Exploration and Management through Rainwater Harvesting, Identification & Management of Drin Drinki king ng Wa Wate terr Pote Potent ntia ial, l, Gr Grou ound nd wate waterr Pote Potent ntia iall Zoni Zoning ng,, Wa Wate ters rshe hed d Ma Mana nage geme ment nt and and irri irriga gati tion onal al Network Planning and tourism. These techniques are also also vit vital tools ools for urb urban and and rural ural dev develop elopin ing g planning.
_______________________ ___________________________________ ____________ * Student, 4th Year, B. Tech in Civil Engineering Mobile: 09830713676 e-mail-
[email protected] 1. Remote Sensing
Remote Sensing is the science and art of acquiring information (spectral, spatial, and temporal) temporal) about material, objects, area, or phenomeno phenomenon, n, without without coming coming into physical physical contact with the objects, or area, or phenomenon under investigation. Without direct contact, some means of transferring information through space must be utilised. In practice, remote sensing is the stand-off collection through the use of a variety of devices devices for gather gathering ing informat information ion on a given given object object or area. area. . In remote remote sensin sensing, g, information transfer is accomplished by use of electromagnetic radiation (EMR). EMR is a form of energy that reveals its presence by the observable effects it produces when it strikes the matter. EMR is considered considered to span the spectrum of wavelengths wavelengths from 1010 mm to cosmic rays up to 1010 nm, the broadcast wavelengths, which extend from 0.30-15mm.
2. Geographic Information System
A Geographic Information System (GIS) integrates hardware, software, and data for capturing, managing, analyzing, and displaying all forms of geographically referenced information. GIS also allows the integration of these data sets for deriving meaningful information and outputting the information derivatives in map format or tabular format. Three Views of a GIS
A GIS can be viewed in three ways: 1) The Database View: A GIS GIS is a uniq unique ue kind kind of datab databas asee of the the worl world— d—aa geogra geographi phicc databa database se (geo (geo databa database) se).. It is an "Infor "Informat mation ion Syste System m for Geogra Geography phy." ." Fundamentally, a GIS is based on a structured database that describes the world in geogra geographi phicc terms. terms. Fig. Fig. 1 schema schematica tically lly represe represents nts a GIS (websi (website te referre referred d in references).
Fig. 1 Schematic representation of a GIS
2) The Map View: A GIS is a set of intelligent maps and other views that show feature featuress and featur featuree relatio relationsh nships ips on the earth's earth's surface surface.. Maps Maps of the underl underlyin ying g geographic information can be constructed and used as "windows into the database" to support queries, analysis, and editing of the information. Fig. 2 schematically represents a GIS (website referred in references).
Fig. 2 Schematic representation of a Map 3) The Model View: A GIS is a set of information transformation tools that derive new geographic datasets from existing datasets. These geo-processing functions take information from existing datasets, apply analytic functions, and write results into new derived datasets. Fig. 3 schematically represents a GIS (website referred in references).
Fig. 3 Schematic representation of a Model
By combining data and applying some analytic rules, we can create a model that helps answer the question you have posed. In the Fig. 4, GPS and GIS were used to acc urately model the expected location and distribution of debris for the Space Shuttle Columbia, whic which h brok roke up upon upon re-e re-ent ntry ry over ver east easter ern n Texas exas on Feb Februar ruary y 1, 2003. 003.
Fig. 4 Together, these three views are critical parts of an intelligent GIS and are used at varying levels in all GIS applications.
3. Application of Remote Sensing and GIS in Civil Engineering
Remote sensing and GIS techniques become potential and indispensable tools for solving many problems of civil engineering. Remote sensing observ observati ations ons provid provides es data data on earth’s earth’s resour resources ces in a spatia spatiall format format,, GIS co-rela co-relates tes different kinds of spatial data and their attribute data, so as to use them in various fields of civil engineering. 3.1 In structural engineering:
Structural Health Monitoring (SHM) provides designers with feedback of structural performance, assisting in development of structures with higher utility and lower manufacturing costs. Structural Health Monitoring nowadays continues to advance from conventional strain gauges to FBG Fibre Optic Sensors (FOS) and major breakthroughs in wireless remote monitoring. Fibre optic sensors use optical wavelength of fibre Bragg grat gratin ing g to meas measur uree temp tempera eratu ture re and and strai strain. n. FOS FOS has has many many adva advant ntag ages es over over the the traditional electrical system such as: • Suitable for long-term permanent SHM: monitor structure during construction stage and whole lifespan as well • No calibration needed
• One cable can have hundreds of the sensors • Simple installation • Cable can run kilometres, no length limit • Fibre optic sensors use light signal - no electrical sparking, intrinsically safe • Gauge length can be few metres long to measure global behaviours of structures • Suitable for both static and dynamic measurement The primary of monitoring is to ensure the longevity and safety of the structure as well as optimizing optimizing its management. management. To implement implement corrective corrective measures measures and maintenance maintenance action, monitoring must be enable the timely detection of any condition or behavior that could deteriorate the structure, deem it unsafe or potentially results in its failure. The monitoring programme plays a fundamental role during the construction phase as it enables the verification of design hypotheses and construction processes, affecting, in some cases, the construction rate of the structures and overall quality. Most defects are introduced already at the time of construction. Monitoring also allows performance evaluation of new materials and technologies used in bridge construction and rehabilitation. This objective is easily achieved with fibre optic sensors since these sensors effectively integrate in new materials such as fibrereinforced polymer composite. Furthermore, fibre optic sensors adapt perfectly to long-term monitoring of bridges behaviour as well as short-term monitoring of bridges dynamic behaviour under traffic load. Finally, monitoring can be used as a tool for “supervised lifetime extension” of bridges approaching the end of their life or in need of major repair. It ensures that such bridges are operated safely while allowing the postponement of major investments and traffic disruption.
(a) (b) Fig. 5 - FBG sensor installation in bridge rebar segments – (a) Individual component of a FBG Sensor and (b) FBG Sensor installed in a bridge.
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Fig. 6 FBG sensor response embedded in concrete structure (CGCRI,Kolkata) 3.2 Regional Planning and Site Investigations:
Site investigations in general require topographic and geologic considerations. Remote sensing data permits such an assessment. In case of dam site investigation, information on topography is essential. Geological consideration involves the different soil and rock types and physical properties. In selecting river-crossing sites for bridges and pipelines, an important consideration is the stability of slopes leading down to and up from the water crossing. Such slopes incl includ udee rive riverb rban anks ks,, terra terrace ce faces faces and and vall valley ey wall wall.. Hist Histor ory y of rive riverr eros erosio ion n and and sedimentation would give clues needed for locating the sites where scour is likely to occur. High spatial resolution satellite data with stereo vision capability can facilitate depth perception in the above said investigations and also for regional planning of large commer commercial cial airpor airports, ts, harbor harbors, s, indust industrial rial towns towns and recreati recreationa onall sites. sites. The hydro hydro geological and geomorphologic information along with geological structures derived from satellite data are very useful in sitting the ground – water bore holes. 3.3 Town Planning and Urban Development:
To achieve the objectives of making metropolis cities more livable and of international standa standard, rd, a co-coo co-coordi rdinat nated ed and integr integrated ated approa approach ch among among the variou variouss agenci agencies es invo involv lved ed in urba urban n deve develo lopm pmen entt and and prov provis isio ion n of serv servic ices es are are need needed ed incl includ udin ing g participatory process in planning and implementation at local body levels. As well as to have planned and organized disposal of population through growth centres, which will acts as counter-magnets to the cities growth. This growth may not able to withstand the existing infrastructure, traffic, road, drainage and utility networks etc. Advance urban planning is required for a planned development of the area for which up to date real time and accurate information are the vital important. Geographical Information system & Remo Remote te Sens Sensin ing g is inev inevit itab able le tech techno nolo logy gy in the the deve develo lopm pmen entt of nati nation onal al Infrastructure and planning and they provide solution related to many environmental
issu issue. e. It is very very much much impo import rtan antt for for urba urban n plan planni ning ng activ activit ities ies & envi enviro ronm nmen ental tal improvement. For sustainable development of urban agglomeration, optimal urban land use plans and resources development models need to be generated by integrating the information on natural resources, demographic and socio – economic data in a GIS domain with the currently available satellite data. 3.4 Environment and Geology :
Whether for irrigation, power generation, drinking, manufacturing, or recreation, water is one of our most critical critical resources. resources. Image interpretat interpretation ion can be used in a variety of ways to help monitor the quality, quantity of water resources. It is well proven in exploring ground water prospect zones. One such example is Rajiv Gandhi Drinking Water Mission with help of remote sensing and GIS. Sediment Sediment pollution is often clearly depicted depicted on aerial and space images. images. Materials that form films on the water surface, such as oil films, can also be detected through the use of aerial and satellite images. Normal colours or ultraviolet aerial photography is often employed for the detection of oil films on water. Thick oil slicks have a distinct brown or black colour. Thinner oil sheens and oil rainbows have a characteristic silvery sheen or iridescent colour banding but do not have a distinct brown or black colour. Jharkhand State now-a- days are affected with ground water scarcity forcing the people to depend on the surface water like lakes, rivers etc. which are polluted like Damodar River and Suwarnrekha river. Damodar river flowing through coal fields is affected with sediment pollution carrying coal mining wastes leading to lowering of water level from November to June. A knowledge of groundwater location is important for both water supply and pollution control analysis. Remote sensing plays a vital role in delineating potential areas of ground groundwat water er occurr occurrenc encee for detaile detailed d explor exploratio ation, n, thus thus reduci reducing ng the cost cost and time time involved in groundwater exploration. Potential groundwater areas cannot be seen on satellite images directly. The clue to the groundwater search is the fact that sub-surface geological elements forming aquifers have almost invariable surface expressions, which can be detected by remote sensing techniques (Joseph, 2005). Satellite data provide information about geomorphic features, structures, land uses and rock types (in a few cases) indicating the presence of groundwater. Some selected landforms and structural feat featur ures es that that are are indi indica cato tors rs for for pote potent ntia iall grou ground ndwa wate terr zone zoness are are vall valley ey fill fills, s, palaeochannels, alluvial fans, dykes, interdunal interdunal depression etc. 3.5Water
Resources Engineering:
By analyzing multi-date RS data, it would be possible to monitor the effects of dam construction. Remotely sensed data of pre and post dam construction can reveal the forest and other land at different water levels. This would also help in preliminary investigation of impact assessment of dams and rehabilitation. To study the feasibility of inter basin transfer of surplus flood flows, RS data can be cost effective. In large area reconnaissance studies, various technically feasible and econom economica ically lly viable viable altern alternativ atives es in locatin locating g surplu surpluss flow flow divers diversion ion routes routes to water water deficient basins can be arrived at. Also, reservoir sites to store the surplus flows in these basins could be identified. Such projects of large dimensions require r equire considerations of land use / land cover, soil and geological mapping, terrain evaluation, construction materia materiall invent inventory ory etc. the latter latter are derive derived d from from satell satellite ite remote remote sensin sensing g data data of particular resolution depending upon the the scale on which such information is required.
The water storage built in through reservoirs, tanks, etc., are often reduced due to sedimentation. Remotely sensed data can be used to monitor the water bodies over time and assess the silting condition. In case of gauged reservoirs of medium to large sizes, RS data can provide an assessment of sediment volume and reduction in the capacity of sediment volume and reduction in the capacity of the reservoir. In case of small water bodies such as tanks, it is possible to come out with a list of problematic tanks with symptoms of heavy siltation and loss of water holding capacity. The condition of tank bunds, fore shore encroachment, etc., also can be analysed with the help of high spatial resolution RS data.
Charac Characteri terizati zation on of water water bodies bodies in terms terms of geolog geological ical,, geomor geomorpho pholog logical ical,, hydro hydro geological, soil and land use / land cover parameters carried out using RS data enables conservation of land and water resources. The RS based input integrated with ground based information through GIS is useful for broad reconnaissance level interpreta tion of land land capabi capabilit lity, y, irrigat irrigation ion suitab suitabilit ility, y, potent potential ial land land use, use, water water harves harvestin ting g areas, areas, monitoring the effects of soil and water conservation measures, estimation of run off and sediment yields and monitoring land use change including land degradation. The commercial areas of irrigation projects are fed by different sources of irrigation like reservoir, tanks, ponds and wells. Assessment of command areas and crops would be highly useful in water release policy or conjunctive use of water in the overall project command area. Satellite data has been advantageously used to obtain such information on surface irrigation projects. In case of floods, appropriate flood management work has to be executed to reduce the damages and utilize the floodwaters. Using multi-date Preflood and post flood images) damage damage due to flood can be successfull successfully y assessed. assessed. This will help in mitigation mitigation and relief distribution. Satellite derived snow cover assessment is being extensively used as an important input in snow melt runoff prediction models to assist in multi purpose reservoir operations. Seasonal snow melt inflow forecasts for Bhakra reservoir in Sutlej basin are being operationally issued every year with the accuracy better than 90% to Bhakra Beas Management Board. 3.6 Landslides:
Landsl Landslide ide is the result result of a wide wide variety variety of proces processes ses which which includ includee geolog geologica ical, l, geomor geomorpho pholog logical ical and meteor meteorolo ologic gical al factors factors.. The The import important ant terrain terrain factors factors are lithology, structure, drainage, slope, land use, geomorphology and road network. A complete landslide hazard assessment requires an analysis of all these factors leading to instability in the region. The feature extraction of some of these factors can be done from from the the inte interp rpre retat tatio ion n of sate satell llite ite imag images es.. With With the the incr increas easee in effic efficie ient nt digi digita tall computing facilities, the digital remote sensing data and their analysis have gained enormous importance. Then the spatial and temporal thematic informations derived from from remote remote sensin sensing g and ground ground based based inform informatio ation n need need to be integr integrated ated for data data analysis. This can be very well achieved using GIS which has the capabilities to handle voluminous spatial data. With the help of GIS, it is possible to integrate the spatial data of different layers to determine the influence of the parameters on landslide occurrence. 3.7 Least cost highway alignment:
Highways are part of the infrastructure that makes up the spinal cord of modern society. GIS provides a valuable tool in the process of planning and design of highways. To obta obtain in an opti optimu mum m high highway way rout routee alig alignm nmen entt whic which h is econ econom omica ical, l, suit suitab able le and and compatible with the environment, various types of data have to consider simultaneously.
Handling Handling and managing this large amount of data manually, manually, is not easy. It is here GIS comes to help, because of its inherent property of handling large bulk of spatial data, non spatial data and its analysis. Remote sensing images of the study area were used as the source (spatial data). Various collateral data from various offices was collected to be used as non spatial data. These images were used to prepare the digitized formats required for the GIS techniques. Using the Resistance concept (such as areas suitable for the new alignment were assigned a low resistance value, whereas the areas not suitable for the new alignment were assigned a high resistance value) the data was prepared for analys analysis. is. Spatia Spatiall Analy Analyst st tool tool of ArcGIS ArcGIS versio version n 8.1 was used used for perfor performin ming g the analysis. 3.8 Terrain Mapping and Analysis:
Assessmen Assessmentt of the performance performance of the terrain for specific developmental developmental activities can be made through terrain evaluation. For this, terrain information can be acquired from RS data and by generating the Digital Terrain Model (DTM). A DTM is an ordered array of numbers representing the spatial distribution of terrain characteristics stored in a computer so as to enable the determination of any quantitative data pertaining to terrain. DTMS is useful in investigation of a number of alternative horizontal and vertical alignments of canals, roads, pipelines or corridors for any such applications. In engineering construction like dam, the knowledge of material comprising the terrain is essential for proper planning, location, construction and maintenance of engineering facilities. For computation of hydrograph parameters like peak runoff rate, time of concentratio concentration n and time to peak, the height and slope slope information information derived from Digital Elevation Model (DEM) are useful. The information on regional engineering soils is essential for general planning and site evaluation purposes. High spatial resolution satellite data can be analyzed to delineate various landforms, mapping of soil classes of significance to engineering construction, delineation of landforms – engineering, soil relationships and grouping of landforms with various physiographic setting or terrain associations. Remote sensing based inventory of construction material such as boulders, quarry rock, sand – clay mixtures etc., would help to locate suitable sites of construction materials for building up of water resources resources engineering engineering projects like dams, bridges, bridges, etc., across the rivers.
4. Conclusion
There are ample evidences of applying the recent advances in satellite based remote sensin sensing g and GIS technol technology ogy in variou variouss fields fields of civil civil engine engineerin ering. g. India’s India’s space space programme ensuring continuous availability of RS data and launching of future satellites carrying high spatial and spectral resolution sensors can go a long way in providing useful information required for civil engineering engineering applications.
5. Acknowledgement
I would like to thank and express my sincere gratitude to Dr. M. Kudrat, scientist, IRSC for his kind inspiration for the preparation of this paper.
6. Reference
1. “An overvi overview ew of Remote Remote Sensing Sensing and GIS applica application tionss in civil civil engine engineeri ering” ng”,, Director, NNRMS-RRSSC, ISRO Headquarters. 2. Application Application Note, Roctest Roctest Ltd., Canada-J4P Canada-J4P 2P4. e-mail:
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