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River Discharge

River Discharge
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(
  b.AVISO website(
2. SARAL/AltiKa data were obtained from MOSDAC website (

Processing Steps

  1. The given range was corrected for
    • path delay in the atmosphere through which the radar pulse passes
    • the nature of the reflecting sea surface
  2. All range corrections are added to the range
  3. Rating curve methodology was developed between Altimeter river height and in-situ river discharge (Rantz et al. 1982).


  1. Coastal and Hydrology Altimetry product (PISTACH), handbook 2010.
  2. 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.
  3. 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.
  4. 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.
  5. 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
    1. Hsat represents the satellite altitude with respect to reference ellipsoid
    2. R represents the satellite range
    3. Cw(w for wet tropospheric)and Cd (d for dry tropospheric) are corrections for delayed propagation in the atmosphere
    4. Ci is the correction delayed propagation through the ionosphere
    5. Cst and Cp represents the correction for solid and polar tides respectively.


  • 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

  1. Limited daily in-situ river discharge data (2007 - 2012) available along Godavari River were obtained from Dowlaiswaram Dam Authorities, Andhra Pradesh.
  2. 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



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:
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:
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
UL Coordinates: 19N, 80.5E
UR Coordinates: 19N, 82.5E
LL Coordinates: 16N, 80.5E
LR Coordinates: 16N, 82.5E
18 Geographic Name, Geographic Identifier Godavari river
19 Bounding box
UL Coordinates: 19N, 80.5E
UR Coordinates: 19N, 82.5E
LL Coordinates: 16N, 80.5E
LR Coordinates: 16N, 82.5E
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