Analysis of lake level changes in Nam Co in central Tibet utilizing synergistic satellite altimetry and optical imagery

Abstract The fluctuations of closed basin lakes on the Tibetan Plateau are a valuable record of climate change induced water balance alterations within the catchments. Since these basins are remote and hard to access, multisensoral remote sensing is a valuable method to gather the necessary water budget components with appropriate spatial coverage and with high temporal resolutions. Thus the lake level elevation changes of the central Tibetan lake Nam Co were examined in example by a comparison of satellite altimetry (RA-2/ENVISAT, GFO radar altimeters and GLAS/ICESat laser altimeter for the period 2000–2009) and the evaluation of a time series of optical satellite data dating back to 1976 (Landsat) and 1965 (Corona) in order to validate hydrological water budget modelling results. The combination of all three altimeters revealed a rising trend of lake level on average by 0.31 m/year in the period 2000–2009 which corresponds to a total volume change of 6.2 km 3 . This is in a good agreement with simulated average lake level rise of 0.35 m/year obtained from distributed hydrological modelling ( Krause et al., 2010 ). The movements of lakeshore measured on the satellite imagery confirm the trend revealed by the altimetry data and they also indicate the rising trend since 1965. While GFO provides a dense time series of data the more accurate ENVISAT/RA-2 data unfortunately feature large data gaps over Tibet. The measurements from time limited campaigns of ICESat validate the results of radar altimetry and they provide unlike radar altimeters a valid height over lake ice during winter and spring period. The results show that the presented approach is a valuable contribution to understand the impact of changing climate on the hydrology of Tibetan lakes.

[1]  Jingshi Liu,et al.  Growth of a high-elevation large inland lake, associated with climate change and permafrost degradation in Tibet , 2009 .

[2]  A. Lang,et al.  Late Quaternary glacier advances, lake level fluctuations and aeolian sedimentation in Southern Tibet , 2002 .

[3]  T. Bolch,et al.  A glacier inventory for the western Nyainqentanglha Range and the Nam Co Basin, Tibet, and glacier changes 1976-2009 , 2010 .

[4]  C. Birkett,et al.  Contribution of the TOPEX NASA Radar Altimeter to the global monitoring of large rivers and wetlands , 1998 .

[5]  Jun Yu Li,et al.  Decadal trend of climate in the Tibetan Plateau—regional temperature and precipitation , 2008 .

[6]  S. Kienberger,et al.  Regional climate projections in two alpine river basins: Upper Danube and Upper Brahmaputra , 2011 .

[7]  Bin Wang,et al.  Tibetan Plateau warming and precipitation changes in East Asia , 2008 .

[8]  Jesus Gomez-Enri,et al.  Water level fluctuations derived from ENVISAT Radar Altimeter (RA-2) and in-situ measurements in a subtropical waterbody: Lake Izabal (Guatemala) , 2008 .

[9]  H. Zwally,et al.  Overview of ICESat's Laser Measurements of Polar Ice, Atmosphere, Ocean, and Land , 2002 .

[10]  J. Crétaux,et al.  Lake studies from satellite radar altimetry , 2006 .

[11]  Jean-François Crétaux,et al.  Evolution of Sea Level of the Big Aral Sea from Satellite Altimetry and Its Implications for Water Balance , 2005 .

[12]  Erich Roeckner,et al.  Evaluation of the hydrological cycle in the ECHAM5 model , 2006 .

[13]  Stephen F. Ackley,et al.  Monitoring lake level changes on the Tibetan Plateau using ICESat altimetry data (2003-2009) , 2011 .

[14]  Shi-chang Kang,et al.  From brightening to dimming in sunshine duration over the eastern and central Tibetan Plateau (1961–2005) , 2010 .

[15]  Hongjie Xie,et al.  Water level variation of Lake Qinghai from satellite and in situ measurements under climate change , 2011 .

[16]  Tandong Yao,et al.  Glacier and lake variations in the Mapam Yumco basin, western Himalaya of the Tibetan Plateau, from 1974 to 2003 using remote-sensing and GIS technologies , 2008, Journal of Glaciology.

[17]  Wei Wang,et al.  The response of lake change to climate fluctuation in north Qinghai-Tibet Plateau in last 30 years , 2009 .

[18]  You Qinglong,et al.  Glaciers and Lake Change in Response to Climate Change in the Nam Co Basin,Tibet , 2009 .

[19]  Anny Cazenave,et al.  Interannual lake level fluctuations (1993–1999) in Africa from Topex/Poseidon: connections with ocean–atmosphere interactions over the Indian Ocean , 2002 .

[20]  C. Birkett,et al.  The contribution of TOPEX/POSEIDON to the global monitoring of climatically sensitive lakes , 1995 .

[21]  C. Birkett,et al.  Synergistic Remote Sensing of Lake Chad: Variability of Basin Inundation , 2000 .

[22]  Peter Krause,et al.  Hydrological system analysis and modelling of the Nam Co basin in Tibet , 2010 .

[23]  C. K. Shum,et al.  ICESat Laser Altimetry in the Great Lakes , 2004 .

[24]  Xiao-dong Liu,et al.  Climatic warming in the Tibetan Plateau during recent decades , 2000 .

[25]  Gravity anomalies from retracked ERS and Geosat altimetry over the Great Lakes: Accuracy assessment and problems , 2008 .

[26]  P. Berry,et al.  Global inland water monitoring from multi‐mission altimetry , 2005 .

[27]  Anny Cazenave,et al.  Caspian sea level from Topex‐Poseidon altimetry: Level now falling , 1997 .

[28]  Carlos R. Mechoso,et al.  Water level fluctuations in the Plata Basin (South America) from Topex/Poseidon Satellite Altimetry , 2002 .

[29]  T. Yao,et al.  Recent Glacial Retreat and Its Impact on Hydrological Processes on the Tibetan Plateau, China, and Surrounding Regions , 2007 .

[30]  A. Cazenave,et al.  SOLS: A lake database to monitor in the Near Real Time water level and storage variations from remote sensing data , 2011 .

[31]  Bob E. Schutz,et al.  A Survey of ICESat Coastal Altimetry Applications: Continental Coast, Open Ocean Island, and Inland River , 2008 .

[32]  M. Frechen,et al.  Late Pleistocene Lake Level Fluctuations of the Nam Co, Tibetan Plateau, China , 2008 .

[33]  Craig S. Lingle,et al.  Airborne and spaceborne DEM- and laser altimetry-derived surface elevation and volume changes of the Bering Glacier system, Alaska, USA, and Yukon, Canada, 1972–2006 , 2009, Journal of Glaciology.

[34]  Yanhong Wu,et al.  The response of lake-glacier variations to climate change in Nam Co Catchment, central Tibetan Plateau, during 1970–2000 , 2008 .

[35]  A. Cazenave,et al.  Preliminary results of ENVISAT RA-2-derived water levels validation over the Amazon basin , 2006 .