Remote Sensing & GIS Applications 3(2+1)

Lesson 3 Remote Sensing Applications

Remote seeing can provide information in two different classes of variables: biophysical ad hybrid. Biophysical variables can provide fundamental biological and/ or physical biophysical information directly, without having to use other surrogate or ancillary data. For example, a thermal infrared sensor can record the apparent temperature of a rock by measuring the radiant flux emitted from its surface. Similarly, it is possible to conduct remote sensing in a very specific region of the electromagnetic spectrum and identify the amount of water vapor in the atmosphere.  It is also possible to measure soil moisture content directly using microwave remote sensing technique.

The second general group hybrid variables, created by systematically analyzing more than biophysical variable. For example, by remotely sensing a plant’s chlorophyll absorption characteristics, temperature, and moisture content, it may be possible to model these data to detect vegetation stress. The variety of hybrid variables is large. Basically, successful remote sensing modeling predicts how much radiant flux in certain wavelengths should exit from a particular object.

At present applications of remote sensing are numerous and varied. They include land cover mapping and analysis, land use mapping, agricultural plant health monitoring and harvest forecast, water resources, wildlife ecology, archeological investigations, snow and ice monitoring, disaster management, geologic and soil mapping, mineral exploration, coastal resource management, military surveillance, and many more.

3.2 Applications of Remote Sensing Technology

Each sensor in remote sensing system is designed for a specific purpose. With optical sensors, the design focuses on the spectral bands to be used. With radar imaging, the incidence angle and microwave band used plays an important role in defining which applications the sensor is best suited for. Each application itself has specific demands, for spectral resolution, spatial resolution, radiometric resolution and temporal resolution.

In the last four decades it has grown as a major tool for collecting information on almost every aspect on the earth. With the availability of very high spatial resolution satellites in the recent years, the applications have multiplied. In India remote sensing has been used for various applications during the last four decades and has contributed significantly towards development.

Some of the important projects carried out in the country include groundwater prospects mapping under drinking water mission, Forecasting Agricultural Output Using Space, Agrometeorology And Land Based Observations (FASAL), forest cover/type mapping, grassland mapping, biodiversity characterization, snow & glacier studies, land use/cover mapping, coastal studies, coral and mangroves studies, wasteland mapping etc. The information generated by large number of projects have been used by various departments, industries and others for different purposes like development planning, monitoring, conservation etc. There can be many applications for remote sensing, in different fields, as described below.

3.2.1 Agriculture

Agriculture plays a dominant role in economies of both developed and undeveloped countries. Satellite and airborne images are used as mapping tools to classify crops, examine their health and viability, and monitor farming practices. Agricultural applications of remote sensing include the following:

• crop type classification

• crop condition assessment

• crop yield estimation

• mapping of soil characteristics

• mapping of soil management practices

• compliance monitoring (farming practices)

• Monitoring of pests and Diseases

3.2.2 Forestry

Forests are a valuable resource providing food, shelter, wildlife habitat, fuel, and daily supplies such as medicinal ingredients and paper. Forests play an important role in balancing the Earth's CO₂ supply and exchange, acting as a key link between the atmosphere, geosphere, and hydrosphere. Forestry applications of remote sensing include the following:

• Reconnaissance mapping: objectives to be met by national forest/environment agencies include forest cover updating, depletion monitoring, and measuring biophysical properties of forest stands.

• Commercial forestry: of importance to commercial forestry companies and to resource management agencies are inventory and mapping applications; collecting harvest information, updating of inventory information for timber supply, broad forest type, vegetation density and biomass measurements.

• Environmental monitoring: conservation authorities are concerned with monitoring the quantity, health, and diversity of the Earth's forests.

3.2.3 Geology

Geology involves the study of landforms, structures, and the subsurface, to understand physical processes creating and modifying the earth's crust. It is most commonly understood as the exploration and exploitation of mineral and hydrocarbon resources, generally to improve the conditions and standard of living in society.

Geological applications of remote sensing include the following:

• Surficial deposit / bedrock mapping

• Lithological mapping

• Structural mapping

• Sand and gravel (aggregate) exploration/ exploitation

• Mineral exploration

• Hydrocarbon exploration

• Environmental geology

• Geobotany

• Baseline infrastructure

• Sedimentation mapping and monitoring

• Event mapping and monitoring

• Geo-hazard mapping

• Planetary mapping

3.2.4 Hydrology

Hydrology is the study of water on the earth's surface, whether flowing above ground, frozen in ice or snow, or retained by soil.

Examples of hydrological applications include:

• Wetlands mapping and monitoring,

• Soil moisture estimation,

• Snow pack monitoring / delineation of extent,

• Measuring snow thickness,

• Determining snow-water equivalent,

• River and lake ice monitoring,

• Flood mapping and monitoring,

• Glacier dynamics monitoring (surges, ablation)

• River /delta change detection

• Drainage basin mapping and watershed modeling,

• Irrigation canal leakage detection

• Irrigation scheduling

• Crop water estimation

• Monitoring of crop water stresses

• Canal water distribution and management

3.2.5 Sea Ice

Ice covers a substantial part of the earth's surface and is a major factor in commercial shipping and fishing industries, coast guard and construction operations, and global climate change studies.

Examples of sea ice information and applications include:

• Ice concentration

• Ice type / age /motion

• Iceberg detection and tracking

• Surface topography

• Tactical identification of leads: navigation: safe shipping routes/rescue

• Ice condition (state of decay)

• Historical ice and iceberg conditions and dynamics for planning purposes

• Wildlife habitat

• Pollution monitoring

• Meteorological / global change research

3.2.6 Land Cover & Land Use

Although the terms land cover and land uses are often used interchangeably, their actual meanings are quite distinct. Land cover refers to the surface cover on the ground, while Land use refers to the purpose the land serves. The properties measured with remote sensing techniques relate to land cover, from which land use can be inferred, particularly with ancillary data or a priori knowledge.

Land use applications of remote sensing include the following:

• Natural resource management

• Wildlife habitat protection

• Baseline mapping for GIS input

• Urban expansion / encroachment

• Routing and logistics planning for seismic / exploration / resource extraction activities

• Damage delineation (tornadoes, flooding, volcanic, seismic, fire)

• Legal boundaries for tax and property evaluation

• Target detection - identification of landing strips, roads, clearings, bridges, land/water interface

3.2.7 Mapping

Mapping constitutes an integral component of the process of managing land resources, and mapped information is the common product of analysis of remotely sensed data.

Mapping applications of remote sensing include the following:

• Planimetry

Land surveying techniques accompanied by the use of a GPS can be used to meet high accuracy requirements, but limitations include cost effectiveness, and difficulties in attempting to map large, or remote areas. Remote sensing provides a means of identifying and presenting planimetric data in convenient media and efficient manner. Imagery is available in varying scales to meet the requirements of different users. Defence applications typify the scope of planimetry applications - extracting transportation route information, building and facilities locations, urban infrastructure, and general land cover.

• Digital elevation models (DEM's)

Generating DEMs from remotely sensed data can be cost effective and efficient. A variety of sensors and methodologies to generate such models are available and proven for mapping applications. Two primary methods for generating elevation data are

1. Stereogrammetry techniques using airphotos (photogrammetry), VIR imagery,   or radar data (radargrammetry), and

2. Radar interferometry.

• Baseline thematic mapping / topographic mapping

As a base map, imagery provides ancillary information to the extracted planimetric or thematic detail. Sensitivity to surface expression makes radar a useful tool for creating base maps and providing reconnaissance abilities for hydrocarbon and mineralogical companies involved in exploration activities. This is particularly true in remote northern regions, where vegetation cover does not mask the microtopography and generally, information may be sparse. Multispectral imagery is excellent for providing ancillary land cover information, such as forest cover. Supplementing the optical data with the topographic relief and textural nuance inherent in radar imagery can create an extremely useful image composite product for interpretation.

3.2.8 Oceans & Coastal Monitoring

The oceans not only provide valuable food and biophysical resources, they also serve as transportation routes, are crucially important in weather system formation and CO₂ storage, and are an important link in the earth's hydrological balance. Coastlines are environmentally sensitive interfaces between the ocean and land and respond to changes brought about by economic development and changing land-use patterns. Often coastlines are also biologically diverse inter-tidal zones, and can also be highly urbanized.

Ocean applications of remote sensing include the following:

• Ocean pattern identification:

• Currents, regional circulation patterns, shears

• Frontal zones, internal waves, gravity waves, eddies, upwelling zones, shallow water bathymetry,

• Storm forecasting

• Wind and wave retrieval

• Fish stock and marine mammal assessment

• Water temperature monitoring

• Water quality

• Ocean productivity, phytoplankton concentration and drift

• Aquaculture inventory and monitoring

• Oil spill

• Mapping and predicting oil spill extent and drift

• Strategic support for oil spill emergency response decisions

• Identification of natural oil seepage areas for exploration

• Shipping

• Navigation routing

• Traffic density studies

• Operational fisheries surveillance

• Near-shore bathymetry mapping

• Intertidal zone

• Tidal and storm effects

• Delineation of the land /water interface

• Mapping shoreline features / beach dynamics

• Coastal vegetation mapping

• Human activity / impact

(Source: geography.huji.ac.il/personal/Noam%20Levin/1999-fundamentals-of-remote-sensing.pdf)

Keywords: Remote sensing applications, Land use / Land cover, mapping, DEM, Planimetry, Hydrology, Agriculture.

References

geography.huji.ac.il/personal/Noam%20Levin/1999-fundamentals-of-remote-sensing.pdf

Suggested Reading

Bhatta B., 2008, Remote Sensing and GIS, Oxford University press, New Delhi, pp. 383-421.

Joseph, G., 2005, Fundamental of remote sensing, Universities Press, pp. 349-388.

ocw.unu.edu/international-network-on-water-environment-and-health/unu-inweh-course-1-mangroves/Application-of-remote-sensing-and-GIS.pdf

Lillesand, T. M., 2002, Remote sensing and image interpretation, Fourth Edition, pp.208-285.

science.jrank.org/pages/5799/Remote-Sensing.html; August 17, 2012

www.isro.org/scripts/remotesensingapplications.aspx; August 10, 2012.