
River heights from satellite altimeters (ENVISAT, Jason-2 and SARAL AltiKa) have been derived at two cross-over points along Godavari River. Subsequently, river height discharge stage relationship between altimetry derived heights and In-situ river discharge has been established. Using this relationship, river discharge database for Godavari River for the period i.e. 2002 - 2015 has been generated.
Data Access
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Data Version
- Version 1.0 (beta)
 
Data Sources
1. GDR tracked data of ENVISAT and Jason-2 (PISTACH Hydrology) at Yanam (estuarine side) and Bhadrachalam (riverine side) for the entire period of respective missions were obtained from
  a. ENVISAT website(http://earth.esa.int/)
  b.AVISO website(http://www.avisooceanobs.com)(Jason-2)
2. SARAL/AltiKa data were obtained from MOSDAC website (http://www.mosdac.gov.in)
Processing Steps
- The given range was corrected for
- path delay in the atmosphere through which the radar pulse passes
 - the nature of the reflecting sea surface
 
 - All range corrections are added to the range
 - Rating curve methodology was developed between Altimeter river height and in-situ river discharge (Rantz et al. 1982).
 
References
- Coastal and Hydrology Altimetry product (PISTACH), handbook 2010.
 - Frappart, F., S. Calmant, M. Cauhope, F. Seyler, and A. Cazenave (2006), Validation of ENVISAT RA-2 derived water levels over the Amazon Basin, Remote Sens. Environ., 100, 252 - 264, doi:10.1016/j.rse.2005.10.027.
 - Rantz, S. E., et al. (1982), Measurement and computation of streamflow: Volume 2. Computation of discharge, Water Supply Paper 2175, U.S. Geol. Surv., pp. 285 - 631.
 - Santos da Silva, J., S. Calmant, F. Seyler, O. C. R. Filho, G. Cochonneau, and W. J. Mansur (2010), Water levels in the Amazon basin derived from the ERS 2 and ENVISAT radar altimetry missions, Remote Sens. Environ., 114, 2160?2181, doi:10.1016/j.rse.2010.04.020.
 - SMMR and DMSP SSM/I-SSMIS Passive Microwave Data. [October 1978 to December 2012]. Boulder, Colorado USA: NASA National Snow and Ice Data CentreDistributed Active Archive Centre.
 
Derivation Techniques and Algorithm
- The observed river height with respect to geoid is given by
 - Rh= Hsat-(R+Cw+Cd+Ci+Cst+Cp) (1)
 - Where
- Hsat represents the satellite altitude with respect to reference ellipsoid
 - R represents the satellite range
 - Cw(w for wet tropospheric)and Cd (d for dry tropospheric) are corrections for delayed propagation in the atmosphere
 - Ci is the correction delayed propagation through the ionosphere
 - Cst and Cp represents the correction for solid and polar tides respectively.
 
 
Limitations
- Based on the availability of the Altimeter dataset over the study region (data gap, altimeter track loss, loss of flooding events, etc.).
 
Known problems with data
- Data problems due to bad weather (heavy rain)
 
Related data collections
- Limited daily in-situ river discharge data (2007 - 2012) available along Godavari River were obtained from Dowlaiswaram Dam Authorities, Andhra Pradesh.
 - Hourly river heights/water levels were provided by Dr. Prakash Mehra, NIO Radar gauge at Yanam (Godavari Estuary) for the period 2008 - 2010.
 
File Naming Convention
- Altimetername_derived_water_height_river_discharge_
 
- Godavari_stationname_starting_date_ending_date
 
- Envisat_derived_water_height_river_discharge_
 
- Godavari_Bhadrachalam_Oct2002_Sep2010.txt
 
MetaData
| Sr. No | Core Metadata Elements | Definition | ||||
| 1 | Metadata language | English | ||||
| 2 | Metadata Contact | MOSDAC | ||||
| 3 | Metadata date | July 20, 2015 | ||||
| 4 | Data Lineage or Quality | Water height estimation and computation of river discharge over Godavari using radar altimeters | ||||
| 5 | Title | Satellite Altimetry derived discharge over Godavari River during 2002-2015 | ||||
| 6 | Abstract | River heights and river discharge have been estimated using ENVISAT and SARAL/AltiKa over two sites and using Jason-2 over one site along Godavari River. The results arevalidated well with the in-situ data. | ||||
| 7 | Dataset Contact | Dr. Rashmi Sharma OSD/AOSG/EPSA (ISRO), Ahmedabad-380015, India. Ph: +91 79 2691 6044. Email: rashmi@sac.isro.gov.in | ||||
| 8 | Update frequency | SARAL/AltiKa and ENVISAT are in 35 day and Jason-2 10 day repetition period | ||||
| 9 | Access Rights or Restriction | Open Access | ||||
| 10 | Spatial Resolution | NA | ||||
| 11 | Language | English | ||||
| 12 | Topic Category | Water height estimation and estimation of river discharge | ||||
| 13 | Keywords | River, Satellite altimeters, river height, range corrections, rating curve | ||||
| 14 | Date or period | ENVISAT (June 2002 to September 2010), Jason-2 ( July 2008 to December 2014) and SARAL/AltiKa (March 2013) | ||||
| 15 | Responsible Party | Dr. Rashmi Sharma OSD/AOSG/EPSA (ISRO), Ahmedabad-380015, India. Ph: +91 79 2691 6044. Email: rashmi@sac.isro.gov.in | ||||
| 16 | Organization | Space Applications Centre (ISRO), Ahmedabad, India | ||||
| 16a | Org. role | Estimation of river discharge using Remote sensing techniques | ||||
| 16b | Vertical Extent (minimumValue, maximumValue, unitOfMeasure, vertical datum) | Unit of measurement = meter for river height and m3/s for river discharge Datum: WGS84 | ||||
| 17 | Geographic Extent | 
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| 18 | Geographic Name, Geographic Identifier | Godavari river | ||||
| 19 | Bounding box | 
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| 20 | Temporal Extent | Time series plot of water heights and river discharge over Godavari river since 2002. | ||||
| 21 | Access Rights or Restrictions | Open Access | ||||
| 22 | Distribution Information | Online download in .txt format | ||||
| 23 | Processing Level | Level 3 (Data product derived from altimeter GDR data) | ||||
| 24 | Reference System | Datum: WGS84 | 
      


