Terminology. Remote Sensing

Absorptance : The ratio of the radiant energy absorbed by a substance to the energy

it receives.

Band : The specific wavelength interval in the electromagnetic spectrum.

Digital image : An array of digital numbers (DN) arranged in rows and columns,

having the property of an intensity value and their locations.

Digital Number : An intensity value of a pixel in a digital image.

Digital Image Processing : The numerical manipulation of DN values for the purpose

of extracting information about the phenomena of the surface they represent.

Electromagnetic Radiation (EMR) : The Energy propagated through a space or a

medium at a speed of light.

Electromagnetic Spectrum : The continuum of EMR that ranges from short wave

high frequency cosmic radiations to long wavelength low frequency radio waves.

False Colour Composite (FCC) : An artificially generated colour image in which

blue, green and red colours are assigned to the wavelength regions to which they do

not belong in nature. For example, in standard a False Colour Composite blue is

assigned to green radiations (0.5 to 0.6 µm), green is assigned to red radiations (0.6

to 0.7 µm and red is assigned to Near Infrared radiation (0.7 to 0.8 µm).

Gray scale : A medium to calibrate the variations in the brightness of an image that

ranges from black to white with intermediate grey values.

Image : The permanent record of a scene comprising of natural and man-made

features and activities, produced by photographic and non–photographic means.

Scene : The ground area covered by an image or a photograph.

Sensor : Any imaging or non–imaging device that receives EMR and converts it into

a signal that can be recorded and displayed as photographic or digital image.

Reflectance : The ratio of the radiant energy reflected by a substance to the energy

it receives.

Spectral Band : The range of the wavelengths in the continuous spectrum such as

the green band ranges from 0.5 to .6 µ and the range of NIR band 0.7 to 1.1 µ.

Comments

Groundwater – Porosity and Permeability

Groundwater refers to the water that resides beneath the Earth's surface in the pores and crevices of rock, sediment, and soil. Two key properties that influence the movement and storage of groundwater are porosity and permeability: 1. Porosity: - Definition: Porosity refers to the volume percentage of void spaces (pores or openings) in a geological material, such as soil or rock. - Role: Porosity determines how much water a subsurface material can hold. It is a measure of the material's capacity to store water. - Factors: Porosity is influenced by the size and arrangement of particles within the material. Highly porous materials have more void spaces, while less porous materials have fewer. - Units: Porosity is expressed as a percentage, with 0% indicating complete solidity (no pore spaces) and 100% indicating complete void space. 2. Permeability: - Definition: Permeability refers to the ability of a geological material to transmit fluids, such as water. It meas

Ground Water

Groundwater Terminology, Concepts, and Facts Key Terms Aquifer: A geological formation that can store and transmit significant quantities of water. Water Table: The upper surface of the saturated zone in an aquifer. Recharge: The process of replenishing groundwater through precipitation or other sources. Discharge: The process of groundwater flowing out of an aquifer, typically into surface water bodies or through wells. Hydraulic Gradient: The slope of the water table. Darcy's Law: A law that describes the flow of groundwater through porous media. Permeability: The ability of a material to transmit water. Porosity: The amount of void space in a material. Concepts Groundwater Flow: Groundwater moves from areas of higher hydraulic head to areas of lower hydraulic head. Groundwater Contamination: The introduction of pollutants into groundwater. Groundwater Depletion: The excessive extraction of groundwater, leading to a decline in water table levels. Saltwater Intrusion:

Artisan Wells Basins

Artisan Wells and Basins Artesian wells are a type of well that harnesses the natural pressure of water trapped underground to force water to the surface without pumping. This phenomenon occurs in specific geological formations known as artesian basins . Key Terminologies and Concepts Aquifer: A geological formation that can store and transmit water. It is typically made up of porous rocks or sediments like sandstone or gravel. Confined Aquifer: An aquifer that is sandwiched between two impermeable layers (like clay or shale) that prevent water from escaping. Artesian Basin: A geological structure where a confined aquifer is tilted and has a recharge area at a higher elevation than the discharge area. This creates a pressure gradient that forces water to flow upwards. Potentiometric Surface: The theoretical level to which water would rise in a well drilled into an artesian aquifer if there were no restrictions. It is determined by the pressure head in the aquifer. Flowing Artesian

Watershed. Catchment. Basin

A watershed, also known as a river basin or drainage basin, is a fundamental concept in geohydrology and hydrology. It refers to a specific geographic area or region of land where all the surface water, including rainfall, snowmelt, and runoff, drains into a common outlet, such as a river, lake, or ocean. Here's an explanation of each term: 1. Watershed: A watershed is essentially a natural hydrological unit defined by the topography of the land. It represents the entire area from which all precipitation and surface water flow eventually gathers at a single point. This point is typically where the main river or stream within the watershed exits into a larger body of water, such as an ocean. Watersheds come in various sizes, from small ones that encompass a few square miles to enormous ones that cover entire continents. 2. River/Drainage Basin: A river basin or drainage basin is another way to describe a watershed. It's the land area that collects and channels water into a river

Discrete Detectors and Scanning mirrors Across the track scanner Whisk broom scanner.

Multispectral Imaging Using Discrete Detectors and Scanning Mirrors (Across-Track Scanner or Whisk Broom Scanner) Multispectral Imaging: This technique involves capturing images of the Earth's surface using multiple sensors that are sensitive to different wavelengths of electromagnetic radiation. This allows for the identification of various features and materials based on their spectral signatures. Discrete Detectors: These are individual sensors that are arranged in a linear or array configuration. Each detector is responsible for measuring the radiation within a specific wavelength band. Scanning Mirrors: These are optical components that are used to deflect the incoming radiation onto the discrete detectors. By moving the mirrors, the sensor can scan across the scene, capturing data from different points. Across-Track Scanner or Whisk Broom Scanner: This refers to the scanning mechanism where the mirror moves perpendicular to the direction of flight. This allows for t

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