ISRO

Observing Reservoir and River Water Levels from Satellite Altimetry

Water security and management require regular monitoring of available water resources such as reservoirs, river, lakes, ponds, soil moisture etc. to devise strategies for water resources planning in the country. Prediction of hydrological extreme events such as drought and flood is crucial for decision-making. Developments in the field of Radar altimetry (SARAL – ALTIKA) is helping to measure fluctuations in water levels of major reservoirs and rivers in India.

The Satellite with ARGOS and ALTIKA (SARAL), a joint Indo-French satellite launched on February 25, 2013 is a mission for oceanographic studies. The payload, Ka-band Altimeter, ALTIKA- built by the French National Space Agency CNES.

Satellite altimeter was originally intended for ocean applications; however, it is also providing important data for inland water levels. Satellite altimetry is based on the measurement of the two-way travel time of short pulse of electromagnetic wave sent out by the satellite and reflected by a water surface. Short pulse of electromagnetic wave is received by Radar altimeter from space platform and range between the satellite and water bodies is measured by correcting atmospheric and geophysical signals. Difference between the satellite altitudes above a reference surface i.e. a conventional ellipsoid is determined through precise orbit computation.

SARAL – ALTIKA satellite data are regularly used to monitor water levels in different rivers (Ganga, Godavari, Brahmaputra, Gandak, Kosi, Yamuna, Son, Ghaghara) as well as 50 major reservoirs over India. Altimeter derived river and reservoir water level product is made available at MOSDAC and VEDAS web portals in near real time.

A detailed study on Ukai reservoir using ALTIKA data revealed lowest water levels in April 2016 since the inception of SARAL- ALTIKA (March 2013). Ukai reservoir water level analysis showed that water volume availability was less by 19.8% in April 2016 as compared to April 2015 whereas 88.5% less in comparison to 2014 for the same time frame. Water volume has improved by 38 % in April 2017 since last year (Apr 2016).  More…

River and Reservoir Water Level Retrieval Locations along with Altimeter Tracks

 

Altimeter Waveforms in a River Transact

 

Altimeter Retrieved River Water Level Fluctuations over Brahmaputra River (Track 352).
ALTIKA detected flood during June 9-12, 2015

 

Altimeter Retrieved Reservoir Water Level Fluctuations over Ukai Dam

 

Inter Annual Variations of Water Level in Ukai and Bansagar Reservoir during Summer