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2012 AGU Chapman Conference on Remote Sensing of the ...

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Sun, WenchaoEstimating River Discharge by <strong>the</strong> HydrologicalModel Calibrated Based <strong>on</strong> River Flow WidthDerived from Syn<strong>the</strong>tic Aperture Radar ImagesSun, Wenchao 1 ; Ishidaira, Hiroshi 2 ; Bastola, Satish 31. College <strong>of</strong> Water Sciences, Beijing Normal University,Beijing, China2. University <strong>of</strong> Yamanashi, K<strong>of</strong>u, Japan3. Nati<strong>on</strong>al University <strong>of</strong> Ireland, Maynooth, IrelandRiver discharge is an integral part <strong>of</strong> terrestrialhydrology and <strong>the</strong> overall hydrological cycle. Thehydrological is a comm<strong>on</strong> tool for estimating river dischargein <strong>the</strong> field <strong>of</strong> hydrology. The dependence <strong>on</strong> observed riverdischarge data for calibrati<strong>on</strong> restricts applicati<strong>on</strong>s <strong>of</strong>models in basins that <strong>the</strong> in situ observati<strong>on</strong> is unavailable.In <strong>the</strong> last decade, <strong>the</strong> river cross-secti<strong>on</strong>al water surfacewidth obtained from remote sensing images, especially from<strong>the</strong> syn<strong>the</strong>tic aperture radar (SAR) which can penetrate <strong>the</strong>clouds, has been proved to be effective to trace riverdischarge from space. In this study, we present a methodusing river widths measured from SAR images for calibratingrainfall-run<strong>of</strong>f models based <strong>on</strong> at-a-stati<strong>on</strong> hydraulicgeometry. One distinct advantage is that this calibrati<strong>on</strong> isindependent <strong>of</strong> river discharge informati<strong>on</strong>. To explore <strong>the</strong>feasibility <strong>of</strong> <strong>the</strong> proposed calibrati<strong>on</strong> scheme intensively andanalyse <strong>the</strong> uncertainty in <strong>the</strong> modelling processquantitively, <strong>the</strong> generalized likelihood uncertaintyestimati<strong>on</strong> (GLUE) was applied. The method is illustratedthough a case study in <strong>the</strong> Mek<strong>on</strong>g basin. The resultsindicate that <strong>the</strong> satellite observati<strong>on</strong> <strong>of</strong> river width is acompetent surrogate <strong>of</strong> observed discharge for <strong>the</strong>calibrati<strong>on</strong> <strong>of</strong> rainfall-run<strong>of</strong>f model. This study c<strong>on</strong>tributesto river discharge estimati<strong>on</strong> in basins that no in situgauging is available.Ensemble simulati<strong>on</strong>s <strong>of</strong> river dischargeSur, ChanyangRelati<strong>on</strong>ship <strong>of</strong> <strong>Remote</strong> sensing-basedEvapotranspirati<strong>on</strong> and Eco-hydrological Factor;Water Use EfficiencySur, Chanyang 1 ; Choi, Minha 11. Civil and Envir<strong>on</strong>ment Engineering, Hanyang University,Seoul, Republic <strong>of</strong> KoreaWater Use Efficiency (WUE) as an eco-hydrologicalparameter, is an index that how amount <strong>of</strong>evapotranspirati<strong>on</strong> (ET) is used for vegetative productivity.This index is defined as <strong>the</strong> ratio <strong>of</strong> Gross PrimaryProductivity (GPP) and ET per unit area. In this study, weextracted GPP and estimated ET using Moderate Resoluti<strong>on</strong>Imaging Spectroradiometer (MODIS) image data tocompute spatio-temporal distributi<strong>on</strong> <strong>of</strong> WUE in North-East Asia. The WUE will c<strong>on</strong>tribute to understand <strong>the</strong> rolevegetative activity <strong>on</strong> hydrologic cycle in <strong>the</strong> ecosystem. Mainpurpose <strong>of</strong> this study is to understand relati<strong>on</strong>ship betweenWUE and remote sensing based ET. ET includingevaporati<strong>on</strong> from a land surface and transpirati<strong>on</strong> fromphotosyn<strong>the</strong>sis <strong>of</strong> vegetati<strong>on</strong> is a sensitive hydrologicalfactor with outer circumstances. Direct measurements EThave a limitati<strong>on</strong> that <strong>the</strong> observati<strong>on</strong> can stand for <strong>the</strong>exact site, not for an area. <strong>Remote</strong> sensing technique isadopted to compensate <strong>the</strong> limitati<strong>on</strong> <strong>of</strong> ground observati<strong>on</strong>using <strong>the</strong> Moderate Resoluti<strong>on</strong> Imaging Spectroradiometer(MODIS) multispectral sensor mounted <strong>on</strong> Terra satellite.Based <strong>on</strong> this study, we estimated Penman-M<strong>on</strong>teith basedevapotranspirati<strong>on</strong> in North-East Asia and compared withremote sensing based WUE in order to understand <strong>the</strong>interacti<strong>on</strong> between atmosphere and vegetati<strong>on</strong> activity.The schematic descripti<strong>on</strong> <strong>of</strong> <strong>the</strong> method138

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