Assessing total water storage and identifying flood events over Tonlé Sap basin in Cambodia using GRACE and MODIS satellite observations combined with hydrological models
Assessing total water storage and identifying flood events over Tonlé Sap basin in Cambodia using GRACE and MODIS satellite observations combined with hydrological models
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DOI：
10.1016/j.rse.2016.03.030
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发表时间：
2016-08
影响因子：
13.5
通讯作者：
N. Tangdamrongsub;P. Ditmar;S. Steele‐Dunne;B. Gunter;E. Sutanudjaja
中科院分区：
文献类型：
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作者：
N. Tangdamrongsub;P. Ditmar;S. Steele‐Dunne;B. Gunter;E. Sutanudjaja
在本研究中，卫星观测数据包括重力 (GRACE)、陆地反射率 (MODIS) 和全球降水 (TRMM) 数据以及 PCR-GLOBWB 水文模型的输出，用于生成每月和次月陆地水储存 (TWS) 估计值，并量化 2002 年至 2014 年间洞里萨盆地的洪水事件。这项研究是首次使用 GRACE 数据来调查洞里萨盆地。为了提高 GRACE 的 TWS 估计的准确性，采用了信号恢复方法来恢复标准 GRACE 后处理方案中固有的信号丢失（即信号泄漏）。该方法仅根据 GRACE 观测进行校正，不需要外部数据或水文模型。该技术在洞里萨盆地的有效性已根据多个独立数据集进行了验证。根据 2002 年以来的 GRACE 观测，明确识别了 2011 年和 2013 年的洪水事件，并测得流域平均 TWS 值分别为 42 厘米（比长期平均峰值高 40%）和 36 厘米（比长期平均峰值高 34%）当量水高。同年也恰逢观测到的最大洪水范围，根据 MODIS 数据估计，洪水范围分别为 6561 平方公里（比长期平均峰值高出 91%）和 5710 平方公里（比长期平均峰值高出 66%）。这些洪水事件还与2010年至2014年观测到的水储存量的年际变化有关。研究表明，这些年际变化主要反映了受降水强度变化影响的地表水和地下水储存成分的变化。此外，本研究提出了一种新方法，通过使用 MODIS 反射率数据以及 GRACE 解决方案来得出定期淹没区域的每月和次月 TWS 变化。本研究结果表明，GRACE 数据可被视为监测某些小规模（82,000 km2）水文流域的有效工具。
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 Tonlé Sap basin between 2002 and 2014. This study is the first time GRACE data have been used to investigate the hydrological processes over the Tonlé 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 Tonlé 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.