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  • Publication
    Open Access
    WOS© Citations 2Scopus© Citations 2  275  55
  • Publication
    Open Access
    Characterizing channel-floodplain connectivity using satellite altimetry: Mechanism, hydrogeomorphic control, and sediment budget
    In this study, a mechanism of channel-floodplain seasonal connectivity over a full hydrological year is assessed mainly utilizing satellite radar altimetry data (Jason-2) in a floodplain along the Amazon River. The proposed observation-based approach employs the concurrent measurement of water levels (WLs) over river and floodplain, analyzing seasonal changes in water surface height differences between the two water bodies. Hydrological connectivity thresholds at different stages during the rising phase were identified, and then validated using field data and remote sensing-driven surface suspended sediment maps. Successful decoupling of the two indiscrete flooding processes during the rising phase: channelized and overbank dispersion processes, is one of the major outcomes of this study. Different roles of the connectivity processes on floodplain hydrogeomorphology are highlighted that channelized flows determine inundation frequency, residence time and development of positive topographic features in the floodplain; while overbank flows contribute good part of the seasonal water storage and sediment budget in the floodplain, and tends to smooth positive topography built by channelized flows. The zones of overbank flooding, however, are rather localized due to the well-developed natural levee complex and stable channel-dominated floodplain along the river bank. Lastly, the presented approach is straightforward based on the publicly available operational dataset and therefore it may be readily adapted by non-remote sensing experts. Thus, along with the emergence of new radar altimetry platforms, such as ICESat-2 or Jason-3 that could measure WL of smaller lakes, the proposed approach offers the potential to contribute to research on channel-floodplain systems in other rivers at a global scale.
    WOS© Citations 29Scopus© Citations 36  289  167
  • Publication
    Metadata only
    Geomorphic control on stage-area hysteresis in three of the largest floodplain lakes
    (2022)
    Ang, Wei Jing
    ;
    ;
    Yang, Xiankun
    Hysteresis in floodplain lakes occurs between stage and lake area. Stage-area hysteresis controls the storage and exchange of water and sediments, and is a critical hydrological behavior for lake management. While hysteresis has been repeatedly observed in the floodplain lakes of large rivers, the hydrological mechanism and factors in control have been poorly understood thus far. In this paper, we investigate the role of geomorphology in controlling lake hysteresis, specifically the geologic setting and the lake basin, the lake position relative to the main stem of the river, as well as the influence of lake shape and its internal depositional landforms on inundation dynamics. We study the floodplain lakes along three of the largest rivers around the world: the Curuai Lake of the Amazon River, the Tonle Sap Lake of the Mekong River, and the Poyang Lake of the Yangtze River. The three lakes exhibit a similar counter-clockwise stage-area hysteresis: for a given stage, the lake area is larger in the falling season than in the rising season. Our results indicate that hysteresis is mainly controlled by geomorphology, where the lake shape and basin size lead to delays in the drainage and drop in lake area during the falling season, resulting in counter-clockwise hysteresis. Nevertheless, the lakes are of distinct climatic and geologic-geomorphic settings, representing the variety in the lake types of large rivers. Hence, while geomorphology is the overall driver, unique lake characteristics delay the fall in water extent and shape hysteresis on a case-by-case nature. At Curuai, the complex floodplain morphology (impeded floodplain) complicates and slows the routing of outflow. At Tonle Sap, the lake flows into the river solely through a narrow channel, where a backwater effect restricts drainage. At Poyang, the wide lake shape upstream leads to counter-clockwise hysteresis, while the narrow channel downstream exhibits clockwise hysteresis. Out of the three investigated floodplains, Tonle Sap has the largest degree of hysteresis (0.41), followed by Poyang (0.17) and Curuai (0.13). This trend in hysteresis extent is a result of the different composition of inflow and the lake–river hydrological connectivity, attributed to lake geomorphology. This study is the first to address geomorphology as the primary control over lake hysteresis, which improves understanding of the stage-area curve in empirical and numerical hydrological models, and potentially floodplain management.
    WOS© Citations 3Scopus© Citations 4  46