Thursday, August 6, 2015


Soil is a natural resource that is fundamental for all human uses. Soil is primarily used for agriculture and soil erosion plays a major role in causing serious disruption in agricultural activity. Soil erosion occurs mainly due to natural disasters like floods and droughts. Prevention and mitigation are effective ways to manage this problem. GIS in conjunction with the Universal Soil Loss Equation (USLE) can be used to evaluate the risk area of soil erosion. The USLE is the most commonly used estimator of soil loss caused by overland erosion. It is used in most parts of the world including India.
The assessment of soil erosion using GIS according to the flowchart shown below:

Each of the USLE factors with associated attribute data is digitally encoded in a GIS database to eventually produce five thematic layers. These are the spatially overlaid to produce a resultant polygonal layer. Application of the USLE model to the resultant layer yields a soil erosion map with classes of soil loss. Thus GIS can provide detailed information to locate areas that are at a risk of soil erosion and areas that are suitable for agriculture.

Definitions of GIS


Toolbox based definitions
(i) GIS is a powerful set of tools for collecting, storing, retrieving at will, transforming and displaying spatial data from the real world (Burrough 1986)
(ii) GIS is a system for capturing, storing, checking, manipulating, analysing and displaying data which are spatially referenced to the Earth (Department of Environment 1987)
(iii) GIS is an information technology which stores, analyses and displays both spatial and non-spatial data (Parker 1988)

Database definitions
(i) GIS is a database system in which most of the data are spatially indexed and upon which a set of procedures operated in order to answer questions about spatial entities in the database.
(Smith et al 1987)
(ii) GIS is any manual or computer based set of procedures used to store and manipulate geographically referenced data. (Aronoff 1989)

Organization based definitions
(i) GIS is an automated set of functions that provides professionals with advanced capabilities for the storage, retrieval, manipulation and display of geographically located data.
(Ozemoy, Smith and Sicherman 1981)
(ii) GIS is an institutional entity reflecting an organizational structure that integrates technology with a database, expertise and continuing financial support over time. (Carter 1989)
(iii) GIS is a decision supporting system involving the integration of spatially referenced data in a problem solving environment. (Cowen 1988)


GIS-Unit 4-Syllabus-OU

GIS-Unit 5-Syllabus-OU

Maps - Basic components, Types of maps & Map analysis

Definitions of GIS




GIS- Basics

Birth and History of GIS

Map projections and spatial referencing

Data types used in GIS

Data formats in a GIS

Data structure in a GIS

Data compression in GIS

Digital Elevation Data

Cartographic database

Conversion of existing digital data

Remotely sensed data

Object Structural Model in GIS

Conflation, edge matching and editing operations in GIS

Analysis functions in GIS

Cartographic modeling by GIS analysis - procedure with an example

Raster Data Analysis

GIS and Knowledge Based Systems

Classification of GIS models

Digital Elevation Data

Editing functions in GIS

Diagram of a Networked Database Structure

A heirarchical database structure based on a simple map

Diagram Showing Vector Topology

Diagram depicting vector and raster representations of map features and their linkage to the attribute database

Diagram depicting linkage between Spatial data and Attribute data in a coverage

Diagram showing the conceptual data model

Map Annotations

Conflation in GIS

Transformation in GIS

Spatial Analysis in GIS

Connectivity functions

Analysis of non spatial attribute data

Important objective questions

Cost-Benefit analysis of an investment in GIS

Text patterns and line styles

Sampling GIS data

Types of errors in GIS data, their elimination and accuracies

Components of data quality

Graphic symbols

Types of errors in GIS

Neighbourhood operations

Record overlay

Modelling in GIS

Simple analysis in GIS

Output formatting

Map transformations

Electromagnetic radiation and its characteristics

Software Scenario Functions: Visibility Analysis

Interaction of EMR with the Earth's surface

Types of Sensors

Diagrammatic representation of types of sensors

Remote sensing data products

Interpretation of remote sensing data

Characteristics of Indian Remote Sensing series of satellite

Software Scenario Functions: Environmental modelling

Software Scenario Functions: Watershed Modelling