Mapping sciences in power sector (part 2)

Posted on Jul 2, 2007 By : Mizake Laziaf
GIS in Power: Site Identification
The remote sensing technology is being used for the identification of suitable sites for locating new hydropower projects. The conventional method could not be directly adopted in the inaccessible areas like Himalayas where the water resource potential is high by means of glaciers and intensive rainfall. Similarly the geological, structural configuration is essential to study to understand the strength and weakness of the area so that the project will be implemented in the suitable terrain (ex. aseismic). For geologic mapping, reflectance information of the rocks in the SWIR and emissivity of the rocks information in the TIR are very important. Again, remote sensing data available in the near infrared region (0.8 um - 1.1 um) provides clearly the contrast between land and water features can easily be discernable. Satellite imagery may be used for the identification of catchment boundary, drainage network, perennial streams, landuse and vegetation cover for these projects. Digitizing the elevation contours and spot heights from topographic maps and using capabilities of various GIS softwares may generate Digital Elevation Model (DEM) of these catchments. The catchment boundary, drainage network and location of major habitation may be overlaid on these DEMs for further analysis.

GIS in Power: Information Processing
Information processing is a key to improve productivity and cutting costs of excess work. Converting information to a computerized format in GIS is more useful and timely for electric utility. For example: GIS will allow to search and retrieve information stored on a server simply by pointing and clicking through user-friendly menus or typing requests in a Windows environment. GIS has a way of making work processes simpler through more productive use of time and information.

Importance of Data
Accurate and current information is vital to maintaining and improving customer service. With GIS, the electric companies will have the ability to improve customer service by better gathering and processing customer information. Through a computerized environment, a GIS can keep information on customers, accurate and current. Improving record-keeping, and making data accessible to more users in more useful forms is vital to improving customer service. Evidently, improving ways of record keeping and data access is possible with GIS; therefore, it can be a key to improving customer service.

Data Sources in GIS

Remote Sensing
Remote Sensing is modern technique in mapping sciences. It is now a major tool to map any area on earth’s surface for transmission of power. The planning for installation of large transmission towers needs proper planning. For this, updated base maps are required. Remote sensing imageries can help in updation of the available topographic maps. The recently launched satellites like IKONOS, IRS-1C,1D(PAN) having its very good spatial resolution of 1mt and 5.8mts through digital image processing techniques; it is able to identify even small features with the resolution as given above. To select site for putting new transmission towers and lines especially in hilly terrains, the density of trees, elevation differences has to be carefully studied in detail. In such cases, remote sensing is the main technology, plays a vital role for the preparation of database on landforms, landuse/landcover and related database. Integrating these information in GIS platform, it is able to generate three dimensional terrain model (DTMs) of the area, which can be further updated with the multidated satellite images and aerial photographsAlso Digital Photogrammetry is the potential technology to provide the informations on terrain elevation which has to be studied before locating site for transmission towers and lines.This has found great success in many European countries but yet to be implemented in the developing countries like India

LIDAR
Besides Remote Sensing the hottest stuff today in the transmission sector is Airborne Laser Terrain Mapping (ALTM) or Light Detection & Ranging (LIDAR) Mapping. Laser mapping produces data with accuracies equivalent to traditional GPS land surveys. But the laser mapping produces these elevation measurements at a rate faster than traditional methods. Since laser mapping provides detailed and accurate elevation information, it can be used at placess where access to the survey property is limited or prohibited. Its rapid turnaround time and operational flexibility give one the edge in competitive bidding situations.

LIDAR data due their typical characteristics are finding many new applications, which were not thought feasible hitherto with other data collection techniques. One such area is monitoring transmission lines. Long stretches of transmission lines can be mapped with speed to determine the exact location of the transmission towers, accurate topography of the corridor, and the encroachment by vegetation for modification and repair purposes.

High resolution DEMs are suited for inspection surveys of powerlines (Figure 1). From the randomly distributed points hitting the wires the wire-lines can be reconstructed by using 3-dimensional line detection and modelling software.

However, inspection does not only include the determination of deformations of the wires, but also the identification of obstructions present in the corridors. For example, deformation caused by trees or illegal buildings standing too close to the powerline path. Their rapid detection and evaluation allows maintenance crews to react fast and to prevent disasters. Also, the inventory of damage after bad weather circumstances can be done easily from Laser DEMs. The required high-resolution mapping necessitates the use of helicopters operating at low altitudes as recording platform.

ALTM can also be used to map rugged terrain like Himalayas for hydropower generation where it is impossible to survey physically using traditional methods. ALTM can be really effective alternative in such case.

Source : http://www.gisdevelopment.net

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