Yaas cyclone induced flash floods influenced many low-lying areas in the coastal regions and changed the turbidity of the wetlands. Study was carried out to assess the impact of cyclone on various Hydrological aspects including surface inundation, rainfall, and water quality. Surface inundation was estimated using synthetic aperture radar Sentinel-1 and Advanced Microwave Scanning Radiometer (AMSR-2) dataset. Optical dataset of Sentinel-2 was analysed to understand the changes in the turbidity of the nearby rivers and lakes. Accumulated rainfall showed a high amount (> 300 mm) of precipitation received at the landfall location in Odisha during the period of 23 May 2021 to 28 May 2021. Heavy flooding was observed in the coastal districts of Orissa including Bhadrak, Kendrapara. Near Digha coast, a high amount of river discharge at the ocean mouth was observed in comparison to pre cyclone time. The turbidity of the water was also observed to be high due to sediments carried by the river.
A fully automated procedure is now established for downloading, processing and publishing of Sentinel1-A&B SAR data on VEDAS. The data Sentinel1_SAR(IW)_GRD is automatically downloaded from Bhoonidhi portal; processed using SNAP tool and published on VEDAS for users. User can perform web-based visualisation and analysis at very high speed.
Following functionalities are available on VEDAS for Sentinel-1 SAR data :
1. Visualisation of daily data for a selected date for VV and VH polarisation.
2. Temporal profile for a pixel is available on click for both polarisations.
3. User defined dynamic mosaic of SAR data can be generated for any number of days.
4. RGB composite for any three dates and polarisation can be generated.
5. Water spread of reservoirs of flooded area can be generated with user defined thresholds.
(Developed by Microwave Techniques Development Division, AMHTDG, EPSA, SAC)
Microwave Data Analysis Software (MIDAS V2.2) is a SAC developed software for the study and analysis of Microwave remote sensing data. MIDAS is a self-sufficient, portable software developed in C++ and Java. It has gsl2, tqdm, libtiff and GDAL as its dependencies. These are provided with MIDAS and it is not required to install them prior to using MIDAS. This software caters to ISRO SAR missions like, RISAT-1, Chandrayaan-2 DFSAR, LS-ASAR (airborne precursor to NISAR mission), etc. Apart from that, MIDAS also supports processing of ALOS-1, RADARSAT-2 and UAVSAR datasets too. It has several polarimetric data analysis features, by providing support to convert data into C3/T3/C4 matrices, speckle-filtering, polarimetric decompositions (Pauli, Yamaguchi, H-A-Alpha etc). MIDAS supports Wishart classification by user-defined RoI selection.
(Developed by Hyperspectral Techniques Development Division (AMHTDG, EPSA, SAC, ISRO, Ahmedabad, Gujarat-380015)
AdVance HYperspectral data Analysis Software (AVHYAS-version-1) is an in-house developed tool for the processing, analysis and visualization of hyperspectral data. AVHYAS tool has been plugged in with QGIS platform which is an open source GIS environment to have the GIS capabilities and extend QGIS for hyperspectral image analysis. AVHYAS is built on back end framework Python 3.7, Scikit-learn, GDAL, tensor flow while front end is QGIS 3.14 with QT designer. Major modules of AVHYAS are atmospheric correction, deep learning classification, data fusion, spectral unmixing, feature extraction, target detection, geophysical applications etc. along with data quality evaluation, preprocessing and basic tools.
This book presents the highlights of various scientific studies in the Antarctic region undertaken by Space Applications Centre (SAC-ISRO) using the earth observation data and decade long experience (2009-2019) of participation in the expeditions to Antarctica coordinated by National Centre of Polar and Ocean Research (ESSO-NCPOR). The studies include technique development and analysis of sea ice, ice sheet and ice shelves using sensors launch by ISRO such as AltiKa, SCATSAT-1, OSCAT, MSMR, RISAT, AWiFS, LISS-III, LISS-IV etc. Field studies include measurements at Bharati and Maitri stations
Drought is a complex natural phenomenon which impact agriculture enormously. Early detection of drought helps stakeholders to take counter measures and provide timely advisories. VEDAS has newly added drought monitoring functionality in its basket by providing widely used Standard Precipitation Index (SPI) and Vegetation Condition Index (VCI).
VEDAS is providing monthly and running 1-month weekly SPI at state as well as taluka levels. Monthly SPI is being calculated using CHIRPS precipitation data while running 1-month weekly SPI is being calculated using NOAA and CHIRPS rainfall data based on 1981-2018 CHIRPS precipitation data. It is available at its vegetation condition dashboard. It is also enabled with spatial analysis (map) as well as data analysis (pie chart and bar chart) functionalities.
Being the highest specific discharge river system in the world, the Brahmaputra river experiences number of long-duration flood waves during the monsoon season annually. Therefore, WRF-Hydro model is setup and is used to predict 3-day water level and inundation probability during the monsoonal flood condition in the Brahmaputra river at Guwahati gauge station and this prediction is visualised on VEDAS.
Water level of various waterbodies over India derived from satellite altimetry is also visualised in Hydrology Application.