Assessing total water storage and identifying flood events over Tonlé Sap basin in Cambodia using GRACE and MODIS satellite observations combined with hydrological models

In this study, satellite observations including gravity (GRACE), terrestrial reflectance (MODIS), and global precipitation (TRMM) data, along with the output from the PCR-GLOBWB hydrological model, are used to generate monthly and sub-monthly terrestrial water storage (TWS) estimates and quantify flood events over the Tonle Sap basin between 2002 and 2014. This study is the first time GRACE data have been used to investigate the hydrological processes over the Tonle Sap basin. To improve the accuracy of the TWS estimates from GRACE, a signal restoration method was applied in an effort to recover the signal loss (i.e., signal leakage) inherent in the standard GRACE post-processing scheme. The method applies the correction based on the GRACE observations only, requiring no external data or hydrological models. The effectiveness of the technique over the Tonle Sap basin was validated against several independent data sets. Based on the GRACE observations since 2002, the 2011 and 2013 flood events were clearly identified, and measured to have basin-averaged TWS values of 42 cm (40% higher than the long-term mean peak value) and 36 cm (34% higher) equivalent water height, respectively. Those same years also coincide with the largest observed flood extents, estimated from the MODIS data as 6561 km2 (91% above the long-term mean peak value) and 5710 km2 (66% above), respectively. Those flood events are also linked to the observed inter-annual variations of water storage between 2010 and 2014. It was shown that those inter-annual variations mainly reflect the variations in the surface water and groundwater storage components, influenced by the change of the precipitation intensity. In addition, this study presents a new approach for deriving monthly and sub-monthly TWS variations over a regularly inundated area by using MODIS reflectance data in addition to GRACE solutions. The results of this study show that GRACE data can be considered as an effective tool for monitoring certain small-scale (82,000 km2) hydrological basins.

[1]  J. Famiglietti,et al.  Satellite-based estimates of groundwater depletion in India , 2009, Nature.

[2]  C. Donlon,et al.  The Global Monitoring for Environment and Security (GMES) Sentinel-3 mission , 2012 .

[3]  S. K. McFeeters.  The use of the Normalized Difference Water Index (NDWI) in the delineation of open water features , 1996 .

[4]  M. Cheng,et al.  Variations in the Earth's oblateness during the past 28 years , 2004 .

[5]  Hubert H. G. Savenije,et al.  A Comparison of Global and Regional GRACE Models for Land Hydrology , 2008 .

[6]  Jeffrey P. Walker,et al.  THE GLOBAL LAND DATA ASSIMILATION SYSTEM , 2004 .

[7]  Changsheng Li,et al.  Mapping paddy rice agriculture in South and Southeast Asia using multi-temporal MODIS images , 2006 .

[8]  Thanapon Piman,et al.  Quantifying changes in flooding and habitats in the Tonle Sap Lake (Cambodia) caused by water infrastructure development and climate change in the Mekong Basin. , 2012, Journal of environmental management.

[9]  S. Swenson,et al.  Methods for inferring regional surface‐mass anomalies from Gravity Recovery and Climate Experiment (GRACE) measurements of time‐variable gravity , 2002 .

[10]  C. Torrence,et al.  A Practical Guide to Wavelet Analysis. , 1998 .

[11]  Oliver Baur,et al.  GRACE‐derived ice‐mass variations over Greenland by accounting for leakage effects , 2009 .

[12]  S. Swenson,et al.  Post‐processing removal of correlated errors in GRACE data , 2006 .

[13]  M. Watkins,et al.  GRACE Measurements of Mass Variability in the Earth System , 2004, Science.

[14]  Michael Durand,et al.  The Surface Water and Ocean Topography Mission: Observing Terrestrial Surface Water and Oceanic Submesoscale Eddies , 2010, Proceedings of the IEEE.

[15]  J. Thepaut,et al.  The ERA‐Interim reanalysis: configuration and performance of the data assimilation system , 2011 .

[16]  Matthias Drusch,et al.  Sentinel-2: ESA's Optical High-Resolution Mission for GMES Operational Services , 2012 .

[17]  Helen Amanda Fricker,et al.  The ICESat-2 Laser Altimetry Mission , 2010, Proceedings of the IEEE.

[18]  M. Bierkens,et al.  Global modeling of withdrawal, allocation and consumptive use of surface water and groundwater resources , 2013 .

[19]  S. Lek,et al.  Diversity and spatial distribution of freshwater fish in Great Lake and Tonle Sap river (Cambodia, Southeast Asia) , 1999 .

[20]  Byron D. Tapley,et al.  Contribution of ice sheet and mountain glacier melt to recent sea level rise , 2013 .

[21]  S. Swenson,et al.  Accuracy of GRACE mass estimates , 2006 .

[22]  C. Jekeli.  Alternative methods to smooth the Earth's gravity field , 1981 .

[23]  Zizhan Zhang,et al.  Long-Term Groundwater Variations in Northwest India From Satellite Gravity Measurements , 2014 .

[24]  M. Bierkens,et al.  Global monthly water stress: 1. Water balance and water availability , 2011 .

[25]  S. M. de Jong,et al.  Calibrating a large‐extent high‐resolution coupled groundwater‐land surface model using soil moisture and discharge data , 2014 .

[26]  M. Kummu,et al.  Water balance analysis for the Tonle Sap Lake–floodplain system , 2014 .

[27]  Ge Sun,et al.  A COMPARISON OF SIX POTENTIAL EVAPOTRANSPIRATION METHODS FOR REGIONAL USE IN THE SOUTHEASTERN UNITED STATES 1 , 2005 .

[28]  C. Kummerow,et al.  The Tropical Rainfall Measuring Mission (TRMM) Sensor Package , 1998 .

[29]  C. Shum,et al.  On the postprocessing removal of correlated errors in GRACE temporal gravity field solutions , 2009 .

[30]  D. Chambers,et al.  Estimating Geocenter Variations from a Combination of GRACE and Ocean Model Output , 2008 .

[31]  J. Famiglietti,et al.  A GRACE‐based water storage deficit approach for hydrological drought characterization , 2014 .

[32]  Brian F. Thomas,et al.  River basin flood potential inferred using GRACE gravity observations at several months lead time , 2014 .

[33]  T. Cochrane,et al.  Historical impact of water infrastructure on water levels of the Mekong River and the Tonle Sap system , 2014 .

[34]  Grzegorz Michalak,et al.  GFZ RL05: An Improved Time-Series of Monthly GRACE Gravity Field Solutions , 2014 .

[35]  T. Sakamoto,et al.  Detecting temporal changes in the extent of annual flooding within the cambodia and the vietnamese mekong delta from MODIS time-series imagery , 2007 .

[36]  Bingxin Yu,et al.  Cambodia's agricultural strategy : future development options for the rice sector : a policy discussion paper , 2011 .

[37]  F. Landerer,et al.  Accuracy of scaled GRACE terrestrial water storage estimates , 2012 .

[38]  A. Hou,et al.  The Global Precipitation Measurement Mission , 2014 .

[39]  W. Peltier.  GLOBAL GLACIAL ISOSTASY AND THE SURFACE OF THE ICE-AGE EARTH: The ICE-5G (VM2) Model and GRACE , 2004 .

[40]  Y. Hong,et al.  The TRMM Multisatellite Precipitation Analysis (TMPA): Quasi-Global, Multiyear, Combined-Sensor Precipitation Estimates at Fine Scales , 2007 .

[41]  F. Bryan,et al.  Time variability of the Earth's gravity field: Hydrological and oceanic effects and their possible detection using GRACE , 1998 .

[42]  Frank Flechtner,et al.  Status of the GRACE Follow-On Mission , 2013 .