1. M. Shah Alam Khan Associate Professor Institute of Water and Flood Management, Bangladesh University of Engineering and Technology Hydro-ecological Investigation WFM 6209 : Interdisciplinary Field Research Methodology in Water Management

2. RS and GIS Applications Examples of Application:  Land type, Land use, Soils Classification  Resource mapping  Crop yield estimation  Drainage network identification  Pollutant spread estimation in water bodies  … …

3. Remote Sensing (RS) Remotely ‘sensing’ the Earth The Earth as seen from spaceSatellite-borne ‘sensing’ platform

4. 2-D representation of remote sensing

5. Characteristics of Satellites  Spaceborne remote sensing is carried out using sensors that are mounted on satellites, space shuttles or space stations.  The monitoring capabilities of the sensor are to a large extent determined by the parameters of the satellite’s orbit.  The path followed by a satellite is its orbit.

6. Characteristics of Orbit Orbital altitude: The average distance from the satellite to the surface of the Earth. Orbital inclination angle: The angle between the orbital plane and the equatorial plane. Orbital period: The time required to complete one full orbit. Repeat cycle: The time between two successive identical orbits.

7. Characteristics of Landsat’s Orbit

8. Types of Orbit Polar orbit: An orbit with inclination angle between 80 0 and 100 0. Sun-synchronous orbit: This is a near-polar orbit chosen in such a way that the sun and the satellite pass the overhead at the same time round the year, so that observation conditions are kept at a constant solar incident angle. Geostationary orbit: This refers to an orbit in which the satellite is placed above the equator (inclination 0 0 ) at an altitude approximately 36,000 km. At this distance the orbital period of the satellite is equal to the rotational period of the Earth.

9. Swath As a satellite revolves around the Earth, the sensor "sees" a certain portion of the Earth's surface. The width of the area imaged on the surface is referred to as the swath. NOAA 17: 2,800 km Landsat 7: 185 km SPOT 5: 60 km IOKONOS: 11 km

10. Earth Observation Satellites  Low-resolution systems: (spatial resolution: 1 km – 5 km)  Medium-resolution systems (spatial resolution: 10 m – 100 m)  High-resolution systems (spatial resolution: <10 m) Low-resolution systems NOAA 17 Orbit: 812 km, 98.7 0 inclination, sun-synchronous Swath width: 2,800 km (FOV = 110 0 ) Off-nadir viewing:  50 0 omnidirectional (all directions) Revisit time: 2-14 times per day, depending on latitude Spatial resolution: 1 km  1 km (at nadir), 6 km  2 km (at edge)

11. Medium-resolution systems Landsat 7 Orbit: 705 km, 98.2 0 inclination, sun-synchronous Swath width: 185 km (FOV = 15 0 ) Revisit time: 16 days Spatial resolution: 15 m (PAN), 30 m (bands 1-5, 7), 60 m (band 6) SPOT 1, 2, 3, 4 Orbit: 832 km, 98.7 0 inclination, sun-synchronous Swath width: 60 km Revisit time: 26 days Spatial resolution: 10 m (PAN), 20 m (Multispectral)

12. Landsat ETM+ Path: 137 Row: 44 Band: 7,4,2

13. Band Wavelength (  m) Application 10.45-0.52(Blue) Coastal water mapping: bathymetry and quality Ocean phytoplankton and sediment mapping Atmosphere: Pollution and haze detection 20.52-0.60(Green) Chlorophyll reflectance peak Vegetation species mapping Vegetation stress 30.63-0.69(Red) Chlorophyll absorption Plant species differentiation Biomass content 40.76-0.90(NIR) Vegetation species and stress Biomass content Soil moisture Applications of Different Bands of Landsat 7

14. Band Wavelength (  m) Application 51.55-1.75(SWIR) Vegetation-soil delineation Urban area mapping Snow-cloud differentiation 610.4-12.5(TIR) Vegetation stress analysis Soil moisture and evapotranspiration mapping Surface temperature mapping 72.08-2.35(SWIR) Geology: mineral and rock type mapping Water-body delineation Vegetation moisture content mapping 80.50-0.90(PAN) Medium scale topographic mapping Image sharpening Snow-cover classification Applications of Different Bands of Landsat 7

15. High-resolution systems SPOT 5 Orbit: 822 km, 98.7 0 inclination, sun-synchronous Swath width: 60 km Revisit time: 2-3 days Spatial resolution: 5 m (PAN) 10 m (Multispectral) IKONOS Orbit: 681km, 98.2 0 inclination, sun-synchronous Swath width: 11km Revisit time: 1-3 days Spatial resolution: 1m (PAN), 4 m (Multispectral)

16. Quickbird satellite image of Banda Aceh before Tsunami Quickbird satellite image of Banda Aceh after Tsunami

17. 1.The data can be directly transmitted to the Earth if a Ground Receiving Station (GRS) is in the line of sight of the satellite (A). 2.If this is not the case, the data can be recorded on board the satellite (B) for transmission to a GRS at a later time. 3.Data can also be relayed to the GRS through the Tracking and Data Relay Satellite System (TDRSS) (C), which consists of a series of communications satellites in geo-synchronous orbit. Data Reception, Transmission, and Processing Data acquired from satellite platforms need to be electronically transmitted to Earth. There are three main options for transmitting data acquired by satellites to the surface.

18. Concept of Remote Sensing Remote Sensing is defined as the science (and to some extent art) of acquiring information about the objects of interest without actually being in contact with it. Data collection by remote sensing This is done by sensing and recording reflected or emitted energy, and processing, analyzing and applying that information.

19. 1.Energy Source or Illumination (A) 2.Radiation and the Atmosphere (B) 3.Interaction with the Object (C) 4.Recording of Energy by the Sensor (D) 5.Transmission, Reception and Processing (E) 6.Interpretation and Analysis (F) 7.Application (G) Elements Involved in Remote Sensing

20. Energy Sources and Electromagnetic Radiation (EMR) All matters with a temperature above absolute zero ( o K) radiates energy in the form of electromagnetic waves of various wavelengths. Electromagnetic radiation is a carrier of electromagnetic energy by transmitting the oscillation of the electromagnetic field through space or matter. Electromagnetic energy can be ‘modeled’ in two ways: by wave motion or particle motion.

21. Wave Motion Electromagnetic radiation can be considered as a transverse wave with an electric field and a magnetic field. The two fields are located at right angles to each other. c =  c = velocity of EM energy (light) = 3  10 8 m/sec = wavelength [m] = frequency [sec -1 or Hz] E = Electric field M = Magnetic field Light is considered as as wave Wavelength and frequency has an inverse relationship

22. Particle Motion (Quantum Theory) Electromagnetic radiation can be treated as a photon or a light quantum. The amount of energy held by a photon of a specific wavelength is given by: E = h  = h  c / where E = energy of a photon [Joules] h = Planck's constant [6.6262  10 -34 J-s] = frequency [Hz]  The longer the wavelength involved, the lower its energy content  Gamma rays (wavelength is around 10 -9 m) are the most energetic and radio waves (> 1 m) the least energetic.  It is more difficult to measure the energy emitted in longer wavelength than in shorter wavelength.

23. The total range of wavelengths is commonly referred to as the Electromagnetic Spectrum. The electromagnetic spectrum ranges from the shorter wavelengths (including gamma and x-rays) to the longer wavelengths (including microwaves and broadcast radio waves). Gamma-ray X-ray Ultraviolet (UV) Visible light Infrared (IR) Microwave Radio wave Electromagnetic Spectrum EM Spectrum Divisions

24. Classification of Electromagnetic Spectrum

25. EM Spectrum Classification (based on wavelength)

26. Electromagnetic Spectrum used in Remote Sensing The spectral range of near IR and short wave IR is sometimes called the reflective infrared (0.7 - 3  m) because the range is more influenced by solar reflection rather than the emission from the ground surface. In the thermal IR range, emission from the ground surface dominates the radiant energy with little influence from solar reflection. Near UV(ultra-violet):0.3 - 0.4  m Visible light: Blue: 0.4 - 0.5  m Green: 0.5 - 0.6  m Red: 0.6 - 0.7  m Infrared (IR): Near IR: 0.7 - 1.3  m Shortwave IR: 1.3 - 3  m Thermal IR: 8 - 14  m Microwave:1 mm - 1 m

27. Types of Remote Sensing with respect to Wavelength 1.Visible and Reflective Infrared Remote Sensing 2.Thermal Infrared Remote Sensing 3.Microwave Remote Sensing

28. How is EMR used in Remote Sensing? 1. Remote sensing devices detect EMR emitted by the Sun after it has interacted with the Earth’s surface 2. Remote sensing devices detect EMR emitted by the Earth itself 3. Remote sensing devices generate their own EMR, bounce it off the Earth’s surface and measure the EMR returned (e.g. RADAR, LIDAR) Three main ‘models’ of how EMR is used in remote sensing ‘Active’ ‘Passive’

29. ‘Atmospheric Windows’

30. Atmospheric Windows Atmospheric windows Wavelength (  m) Upper UV – photographic IR Reflected IR Thermal IR Microwave 0.3 – 1(approx.) 1.3, 1.6, 2.2 3-5, 8-14 > 5000 refer to the relatively ‘transparent’ wavelength regions of the atmosphere Those portions of the spectrum which are not severely influenced by atmospheric absorption, and thus are useful to remote sensors, are called atmospheric windows.