Sustainable Development Goal on water (SDG 6) Mapping water quality using high resolution satellite remote sensing data
The online portal will also help developing countries like Pakistan to build capacity and competence in their technical and administrative infrastructures. The maps in following figures shows:
- Chlorophyll-a CHL an essential pigment included in phytoplankton cells and therefore a measure of phytoplankton. The displayed CHL is calculated from total scattering and total organic absorption of water constituents. Unit is [µg/l].
- Harmful Algae Blooms (HAB) indicator shows possible areas affected by harmful algae blooms formed by cyanobacteria containing phycocyanin.
- Total Absorption (ABS) is the absorption of organic and anorganic of water components is provided as absorption unit in [1/m].
- Turbidity measures the degree to which light is being backscattered by particles in the water.Turbidity caused by scattering of particles is provided in Formazine Turbidity Unit [FTU].
Figure: Karachi a Metropolitan city located on the coastline of Sindh province in southern Pakistan, along a natural harbour on the Arabian Sea. (1) Turbidity and (2) Chlorophyll-a.
Figure: The Mangla Dam is a multipurpose dam located on the Jhelum River in the Mirpur District of Azad Kashmir. (1) Chlorophyll-a , (2) HAB indicator (probability), (3) Total Absorption, and (4) Turbidity.
Figure: Gomal Zam Dam is a multi-purpose gravity dam in South Waziristan Agency of Federally Administered Tribal Areas (FATA), Pakistan. (1) Chlorophyll-a , (2) HAB indicator (probability), (3) Total Absorption, and (4) Turbidity.
Figure: Ghazi-Barotha Hydropower Project is a 1,450 MW run-of-the-river hydropower connected to the Indus River about 10 km west of Attock in Punjab, Pakistan. (1) Chlorophyll-a , (2) HAB indicator (probability), (3) Total Absorption, and (4) Turbidity.
Note: Please read the information booklet for further information on the water quality products and to learn more about the validity range of the products. Products are generated independent on any form of ground truth data, and inter-comparable over the various resolutions provided. The Chlorophyll and HAB indicator may have site-specific limitations e.g. for extremely humid, calcareous, or ferruginous waters, and can be improved with local adaptations. General restrictions are caused by clouds, optical shallow waters, or undetected artefacts from e.g. cloud shadows.
RECENT combines a data from Multiple Satellites Observations Monitor and Assess Impact from Drought in Regional Scale. Daily/Monthly Drought index data with Satellite Rainfall and Land Surface Temperature are available to Visualize and Download through this Web Site (http://iis.gic.ait.ac.th).
The RECENT service is available for countries; Bangladesh, Bhutan, Cambodia, China, India, Indonesia, Lao_PDR, Mongolia, Myanmar, Nepal, Pakistan, Philippines, SriLanka, Thailand & Vietnam.
Satellite observed Rainfall and Land Surface Temperature data are used here to obtain a daily drought product called Keetch-Byram Drought Index (KBDI), which ranges from 0 (wet condition) to 800 (dry condition). Anomaly of drought index (KBDI) which is deviation from long term average if Drought Index is an Indicator of Drought Condition. Hourly global rainfall data at 0.1° spatial resolution is obtained from GSMaP NRT System by Japan Aerospace Exploration Agency (JAXA). It is derived from microwave radiometers (e.g., TMI, AMSR-E and SSM/I) and infrared radiometers (e.g., MTSAT, METEOSAT and GOES). This is an hourly rainfall product which is available to public after 4 hours after the observations. Land Surface Temperature (LST) data are obtained from MTSAT, a weather satellite of the Japan Meteorological Agency (JMA) with a spatial resolution of 4 km. LST is observed in every 30 minutes using 4 thermal-infrared channels.
The service is run and managed by:
Institute of Industrial Science, University of Tokyo Japan (https://www.iis.u-tokyo.ac.jp/)
Geoinformatics Center, Asian Institute of Technology Thailand (http://www.geoinfo.ait.asian/)
- Drought Index KBDI (Link) (PDF) (PDF) (PDF)
- Consistency of satellite-based precipitation products in space (PDF)
- Product Tutorial on Land Surface Temperature (Link)
- JAXA Global rainfall watch (Link) (PDF) (PDF) (PDF) (PDF) (PDF)
- JAXA Global rainfall watch web tool (Link)
Monitoring air pollutants distribution in urban areas are critical for public health and safety. A country like Pakistan with no network of advanced weather stations to extract high quality data to derive information products is very important. Trend maps of pollutants and other information parameters derived from satellite remote sensing data is a replicable technique to integrate into management decisions. This allows city management to effectively monitor visibility and air quality concerns informing public for to take effective measures.
Following are examples of the available satellite remote sensing products for air quality measurements.
- Aerosol Optical Depth/Thickness product provides information on aerosol in the atmosphere.
- Fires and Thermal Anomalies product shows active fire detection (including crop burning) and thermal anomalies.
- Normalized Difference Vegetation Index (NDVI) is a measure of greeness and health of vegetation.
1. Aerosol Optical Depth
MODIS (Terra and Aqua) Combined Value-Added Aerosol Optical Depth (Temporal Coverage: 31 January 2013 – present). The MODIS (Terra and Aqua) Combined Value-Added Aerosol Optical Depth layer is a value-added layer based on MODIS Level 2 aerosol products. The layer can give a quick, synoptic view of the level of aerosol in the atmosphere.. MODIS Aerosol Optical Depth (or Aerosol Optical Thickness) layer indicates the level at which particles in the air (aerosols) prevent light from traveling through the atmosphere. Aerosols absorb and scatter incoming sunlight, which reduces visibility and increases the optical depth. An optical depth of less than 0.1 indicates a clear sky with maximum visibility, and a value of 1 indicates the presence of aerosols so dense that people would have difficulty seeing the Sun. Aerosols have an effect on human health, weather and the climate. Sources of aerosols include pollution from factories, smoke from fires, dust from dust storms, sea salts, and volcanic ash and smog. Aerosols compromise human health when inhaled by people with asthma or other respiratory illnesses. Aerosols also have an affect on the weather and climate by cooling or warming the earth, helping or preventing clouds from forming.
This level 3 gridded product is designed for quantitative applications including aerosol data assimilation and model validation. This layer is useful for aerosol forecasting communities such as the United States Navy Fleet Numerical Meteorology and Oceanography Center (FNMOC), National Oceanic and Atmospheric Administration (NOAA), European Centre for Medium-Range Weather Forecasts (ECMWF), National Aeronautics and Space Administration (NASA) Global Modeling Assimilation Office (GMAO), University research groups and support for field/aircraft campaigns.
The MODIS Combined Value-Added Aerosol Optical Depth layer is a near real-time layer and available as a combined Terra satellite and Aqua satellite layer (MCDAODHD). The sensor resolution is 0.5 degrees, imagery resolution is 2 km, and the temporal resolution is daily.
References: NASA Earthdata – NRT Value-Added MODIS AOD Product; GCMD Entry: MCDAODHD
2. Fire and Thermal Anomalies
MODIS (Terra) Fire and Thermal Anomalies Temporal Coverage: 8 May 2012 – present. The MODIS Fire and Thermal Anomalies layer shows active fire detections and thermal anomalies, such as volcanoes, and gas flares. Fires can be set naturally, such as by lightning, or by humans, whether intentionally or accidentally. Fire is often thought of as a menace and detriment to life, but in some ecosystems it is necessary to maintain the equilibrium, for example, some plants only release seeds under high temperatures that can only be achieved by fire, fires can also clear undergrowth and brush to help restore forests to good health, humans use fire in slash and burn agriculture, to clear away last year’s crop stubble and provide nutrients for the soil and to clear areas for pasture. The fire layer is useful for studying the spatial and temporal distribution of fire, to locate persistent hot spots such as volcanoes and gas flares, to locate the source of air pollution from smoke that may have adverse human health impacts.
The MODIS Fire and Thermal Anomalies product is available from the Terra (MOD14) and Aqua (MYD14) satellites as well as a combined Terra and Aqua (MCD14) satellite product. The sensor resolution is 1 km, and the temporal resolution is daily. The thermal anomalies are represented as red points (approximate center of a 1 km pixel) in the Global Imagery Browse Services (GIBS)/Worldview.
References: MOD14; MYD14; FIRMS Near Real-Time MODIS Active Fire Data; MODIS Collection 6 Active Fire Product User’s Guide
3. Normalized Difference Vegetation Index (NDVI)
Normalized Difference Vegetation Index (NDVI) (rolling 8-day) MODIS rolling 8-day Normalized Difference Vegetation Index (NDVI). The MODIS Normalized Difference Vegetation Index (NDVI) layer is a measure of the greenness and health of vegetation. The index is calculated based on how much red and near-infrared light is reflected by plant leaves. The index values range from -0.2 to 1 where higher values (0.3 to 1) indicate areas covered by green, leafy vegetation and lower values (0 to 0.3) indicate areas where there is little or no vegetation. Areas with a lot of green leaf growth, indicates the presence of chlorophyll which reflects more infrared light and less visible light, are depicted in dark green colors, areas with some green leaf growth are in light greens, and areas with little to no vegetation growth are depicted in tan colors.
The MODIS rolling 8-day NDVI layer is available as a near real-time, rolling 8-day product (MOD13Q4N) from from the Terra satellite. It is created from a rolling 8-day land surface reflectance product, MOD09Q1N. The sensor resolution is 250 m, imagery resolution is 250 m, and the temporal resolution is an 8-day product which is updated daily.
References: NASA Earth Observatory – Measuring Vegetation; NASA Earthdata – New Vegetation Indices and Surface Reflectance Products Available from LANCE; NASA NEO – Vegetation Index
Karachi, the largest city of Pakistan received heavy monsoon rain August 30, 2017. The flood in Karachi due to heavy rains is the continuation of the similar monsoon related flooding crisis in the South East Asia region (India, Bangladesh etc.).The Flood map below is derived (subset of Karachi city ) from European Space Agency (ESA)’s Copernicus Program SENTINEL-1 Synthetic Aperture RADAR (SAR) image acquired on September 01, 2017. The green color in the map shows the flooded region.
The total rainfall derived from satellite data (GPM IMERG) for Karachi from August 29-31, 2017 is shown in Figure below:
Khyber Pakhtunkhaw (KPK) provincial government in Pakistan, govern by the Pakistan Tehreek-e-Insaf (PTI) party launched a reforestation program named “Billion tree Tsunami”, in 2015 (@btap2015). Imran Khan (@ImranKhanPTI), a cricket super star turned politician is the head of PTI party, Prime Minister of Pakistan and main driver behind this massive plantation campaign to turn degraded into forested land. The important aspect of this project is to monitor and identify the growth of these plantation regions. The remote sensing and Geographic Information Systems (GIS) tools provides this near-real-time (NRT) information at low cost compared to field campaigns.
The well known method to identify and monitor land surface changes using satellite remote sensing data utilizes a combination of band thresholding and optical indices (such as Normalized Difference Vegetation Index – NDVI) to separate land surface features. Applying this approach to two separate images by a given period of time allows changes in the extent of the area of interest to be identified. The atmospheric correction to the two images separated over time, extent of land can be compared. allowing for changes to be identified. this approach will provide an excellent alternative to field level change detection methods in challenging environments across Pakistan. We tested this approach for Bannu forest region (as shown in the Figure 2). The Figure 1 shows the land cover map of Bannu region for the year 2015.
Two Landsat 8 images are used for this study area acquired in June 01, 2013 and June 12, 2017. The Landsat 8 images are freely available from the United States Geological Survey (USGS) “EarthExplorer” (https://earthexplorer.usgs.gov/). The images were converted into surface reflectance before NDVI calculations using a standardised approach ( for detail check http://landsat.usgs.gov/CDR_LSR.php).
Figure 4: NDVI map of Bannu forest region derived from Landsat 8 image acquired on June 12, 2017.
Figure 5: NDVI map in KMZ format of Bannu forest region derived from Landsat 8 image acquired on June 01, 2013 shown in google earth.
Figure 6: NDVI map in KMZ format of Bannu forest region derived from Landsat 8 image acquired on June 12, 2017 shown in google earth.
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