gis

INTRODUCTION:

A geographic information system (GIS) is a system designed to capture, store, manipulate, analyze, manage, and present all types of geographical data.  The key word to this technology is Geography – this means that some portion of the data is spatial.  In other words, data that is in some way referenced to locations on the earth.

Geographical

The ‘spatial key’ or location of features is central to data handling, analysis and reporting, which sets GIS apart from other data base management systems.

Information

Without data and information GIS can have no role to play and good quality data are critical if the results of analysis are to be reliable.

Systems

At a basic level they are computer-based systems, but it is important to remember that GIS are rarely personal technology, so an understanding of how organizations manage data and use information is critical to understanding and achieving effective use of GIS.

More recently Geographical Information (GI) as a term has become more widely used in its own right. GI handling has become much more tightly embedded into a wider range of technologies than ten years ago and GIS as a term is being precisely defined as desktop systems with a powerful range of functionality. GI handling technologies including, for example, addressing software which is used by call center operators who ask for postcode and house number only, and indeed such technologies are instrumental in the increase in both amount and quality of GI that is available for application and analysis in a GIS.

APPLICATIONS OF GIS:

A significant difference between GIS applications is whether the geographic phenomena studied are man-made or natural. Using GIS for the purpose of developing a town or city comprises a study of man-made things mostly, the roads, sidewalks, and at larger scale, suburbs and transportation routes are all made by man. These entities often have—or are assumed to have—definite boundaries, we know, for instance, where one road ends and another begins. On the other hand, geomorphologists, ecologists and soil scientists often have natural phenomena as their study objects. They may be searching fort rock formations, plate tectonics, distribution of natural greenery or soil units. Often, these entities do not have specific boundaries, and there exist changeover where one vegetation type, is progressively replaced by another.

It is not rare, obviously, to find GIS applications that do a bit of both, specifically they involve both natural and man-made entities. Examples are common in areas where we study the consequence of human activity on the environment. Railroad construction is such an area, it may contain parcels to be reclaimed by a mining engineer could be interested in determining which prospect copper mines are best fit for future exploration, taking into account parameters such as extent, depth and quality of the ore body, amongst others;

• a geoinformatics engineer appointed by a telecommunication organization may want to determine the best sites for the company’s relay stations, taking into account a number of cost factors such as land prices, undulation of the terrain and so on.
• a forest manager might want to improve timber production utilizing the statistics of soil and present tree stand distributions, in the existence of a number of operational constraints, such as the requirement to preserve tree diversity.
• a hydrological engineer might want to study about water quality parameters of different sites in a freshwater lake to improve her/his understanding of the current distribution of coral reef beds, and why it be different so much from that of a decade ago. Government, it deals with environmental impact assessment and will generally be influenced by many restrictions, such as not crossing seasonally flooded lands, and staying within inclination extremes in hilly terrain. There are many applications of GIS, and we can use it according to our requirement. Some of the applications of GIS are mentioned below.

APPLICATION OF GIS IN GEOMORPHOLOGY:

Topography and geomorphology are essential research subjects in geography, geomorphometric investigation is a significant part of GIS. Since the advancement of geomorphometry is about 50 years ago, critical advancement has been made in the related theory, procedure and applications. Prior to the presentation of geographical information systems (GISs) to geomorphology, manual geomorphologic examinations were tedious and hard to perform, particularly when numerous geomorphologic indicators were incorporated.  The utilization of GISs got famous in 1980’s for geomorphologic order research, and GIS-software gave a solution for dealing with huge spatial datasets. Such software likewise could give a logically stable representation and spatial investigation of geomorphology. (Gustavsson et al., 2008).

APPLICATION OF GIS IN DISASTER MANAGEMENT:

The expert earthquake database (EEDB)

There was a previous GIS version, an EEDB system (Camus H. & Debuisson. J 1964) which had a wide range of seismological applications. It was gradual conversion from a conventional GIS to advanced expert system updated by including successively various mathematical methods for earthquake data processing, new parameters of seismic regime, and advanced representation tools. The realized algorithms (Diouf. S., et al 1999.) allow the user to compute and visualize maps and diagrams of seismicity parameters (slope of magnitude-recurrence curves, seismic quiescence, earthquake density, etc.), to reveal clustering of events, and remove aftershocks. Modifications and versions of GIS-EEDB for different geodynamic regions (Bassot J.P., et al 1966) are illustrated in the chapter with case studies of seismic anomalies.

Visualization and analysis of EISC data

Applying the EEDB system software to EISC data (Bassot J.P.,et al 1966)  (in the new GIS system, called Earth’s Impact Structures Catalog (EISC)) allows gaining insights into spatial patterns of impact structures. In addition, the shapes of craters are constrained using a shaded relief model based on NASA data arrays of SRTM (Shuttle Radar Topography Mission) and ASTER GDEM (Global Digital Elevation Model), and the technology of digital mapping. Thus typical elements of impact craters morphology have been systematized and can be used as indicators of the crater origin (Engaenc. M (1978).

APPLICATION OF GIS IN WASTE MANAGEMENT:

The most prominent application of GIS for waste collection is route optimization to improve routing strategies and lessen vehicle emissions.(Jovicic et al. 2011) used ArcGIS network analyst functionality to estimate the potential for reducing fuel consumption and thus the emission of carbon dioxide (CO2) through the communal vehicles route optimization. A Study about application of GIS in waste management, indicated an approximate annual savings of 1,700 miles for one collection vehicle within the City of Kragujevac, Serbia.

Further, the most fuel-economical route was extracted and compared with the original route, and with the routes extracted from criterions concerning the traffic time and shortest distance. According to available information for the City of Kragujevac and the results from this study, it was estimated that the total savings could be 20% in costs and the associated emissions. Bhambulkar (2010) also used ArcGIS network analyst to identify best routing for municipal solid waste that cannot be collected by standard waste collection trucks, due to size and other prohibitive obstacles in the municipality of Nagpur, India. Optimal routing was cost effective and less time consuming when compared with the existing route with a monthly savings of 14%.

APPLICATION OF GIS IN GROUNDWATER STUDIES:

GIS is an effective tool for analyzing spatial and temporal data of water quality (Burrough and McDonnell, 1998). Information on spatial and temporal variability/trends of water quality is very helpful in the decision-making process (Freeze and Cherry, 1979). In addition, water quality mapping is essential for monitoring, pollution hazard assessment, modeling and environmental change detection (Goodchild et al., 1993; Skidmore et al., 1997; Chen et al., 2004; Jha et al., 2007). In a GIS framework, point estimates of water quality parameters can be spatially interpolated by spatial interpolation techniques such as kriging, inverse distance weighting, etc. to develop parameter concentration maps at different time scales or other related maps.

GIS presents spatial information in the form of maps where different features are located by symbols, and is integrated with databases containing multiple attributes data of the mapped features. A map helps providing knowledge of where and what things are, and how they are related. The GIS database containing spatial and point attributes can then be used to generate interactive reports and maps, which in-turn can support decision-making about the best design alternatives and their impacts. Furthermore, GIS-based maps serve as powerful communication medium in presenting information in such a way that the people involved in the planning and management of water quality can better understand and get more involved.

APPLICATION OF GIS IN LAND DEGRADATION:

Land degradation Irrigated agriculture areas often face problems of water logging and salinity. The problems are refereed as twin problem as water logging leads to soil salinization in long run. Identification of extent of the affected area is prerequisite for reclamation. Criteria adopted for water logging are given in Table 1.1. Criteria for salinity and sodicity are listed in Table 1.2. Area with surface pondage and moist soil can be delineated easily using remote sensing data. Water has black tone in standard FCC in visible and near IR bands. Most soil has dark signature in these imageries. Shallow water table conditions often are not detected using optical remotely sensed data unless its expression is visible on the surface of the earth. Areas where yield is affected can be monitored.

GIS Criteria adopted for waterlogging

Waterlogging	National Commission on Agriculture (1976)	Ministry of Water Resources, Go1 (1991)
Waterlogged/ Critical	Water table < 1.5 m	Water table < 2 m
Potentially waterlogged		Water table 2-3 m
Safe area		Water table > 3 m

GIS Criteria for soil salinity/ Sodicity

Degree of salinity /Sodicity	Salinity EC (dSm-1)	Sodicity
pH	ESP
Slight	4-8	8.2-9.0	<15
Moderate	8-25	8.2-9.0	15-40
Strong	>25	9.0-9.8	>40

Saline areas possess salt efflorescence on the surface. Due to this, saline areas have bright appearance in optical remote sensing. Sodic area has different signature than saline areas. In sodic areas, the infiltration is very less and thus water gets stagnant in the areas and thus the area can be identified through surface pondage and moist soil. Both, saline and sodic areas have poor growth of vegetation. Waterlogged areas can also be delineated using GIS technique using water depth map. The map is processed to correct any discrepancies in depths (e.g. negative values). The maps can be utilized to classify areas as waterlogged/ critical, potential waterlogged and safe.

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