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

seasonal trends, and integrate cloud cover data from theGeostationary Environmental satellites for an improvedtemporal resolution.Baugh, CalumUsing field data to assess the effectiveness ofadjusted spaceborne derived DEMs for replicatingAmazon River floodplain hydro-dynamicsBaugh, Calum 1 ; Yamazaki, Dai 2, 3 ; Hall, Amanda 1 ; Bates,Paul 1 ; Schumann, Guy 11. School of Geographical Sciences, University of Bristol,Bristol, United Kingdom2. Institute of Industrial Science, The University of Tokyo,Tokyo, Japan3. Byrd Polar Research Center, Ohio State University,Columbus, OH, USAHydro-dynamic modelling requires accurate DEM datato provide the topographic boundary condition. In the caseof the Amazon, vegetation distortion of the only suchavailable dataset (SRTM) can degrade the accuracy of thismodelling. However the extent of these impacts are not yetfully understood because of the lack of hydro-dynamic fieldobservations from the floodplain. Such field data can beused firstly to identify the original impact of vegetationdistortion upon a hydro-dynamic simulation. Second, it canassess the effectiveness of DEM adjustment algorithms atremoving the distortion. Therefore, to address this issue thefollowing data were collected within the floodplain 250 kmupstream from Manaus on the central Amazon mainstemduring July 2011; flow velocity, direction and depth, watersurface elevation and tree height. A hydro-dynamicsimulation using the LISFLOOD-FP model was thenperformed using the original SRTM DEM. Comparing thesimulation results to the field flow data showed pooragreement, for example the velocity gradients differed by twoorders of magnitude. Therefore a version of the SRTM DEMfrom Yamazaki et al., (submitted to J. Hydrol) who adjustedit to better include floodplain channels was used. Thisdemonstrated greater agreement between the field flow dataand the model in areas of channelized floodplain flow.However a comparison of water surface elevations betweenthe field and modelling data showed that vegetationdistortion still remained in the adjusted DEM. A vegetationcorrection method, validated using the tree height field data,was then applied to the adjusted DEM. The results showedthe greatest agreement between the field and modellingdata. This work therefore shows how floodplain hydrodynamicdata collected in the field can be used to validateand correct an adjusted DEM in the context of hydrodynamicsimulations of large remote rivers.Becker, Matthew W.Wetlands as Groundwater Piezometers in BorealForestsBecker, Matthew W. 1 ; Babonis, Gregory S. 2 ; Fredrick, Kyle C. 31. Dept Geological Sciences, California State Long Beach,Long Beach, CA, USA2. Geology, University at Buffalo, Buffalo, NY, USA3. Department of Earth Sciences, California University ofPennsylvania, California, PA, USABoreal forests are considered a critical component ofglobal carbon cycling. Groundwater plays an important partin boreal forests as depth to water table influencesbiodiversity and groundwater discharge provides droughtresistance and nutrients for plants. Understanding howgroundwater influences these remote ecologicalenvironments on a sub-continental scale requires the use ofremote sensing combined with hydrologic models. Wepresent an example of such an application, in whichwetlands and seepage lakes are used as groundwaterhydraulic head observations in a numerical flow model. Thetest area is the Northern Highland Lakes Region ofWisconsin, USA, which is a southern boreal / temperateforest biome punctuated by kettle lakes, wetlands, and bogs.These surface water features are often well connected togroundwater so can serve as measurements of groundwaterhydraulic head which, in turn, can be used to determinegroundwater flow and storage and its potential forbiogeochemical transport. The key is to isolate those featuresthat are hydraulically connected to groundwater and thenmake accurate elevation measurements of their surface. Toisolate seepage lakes that were well connected togroundwater we used thermal band temperaturemeasurements from the ASTER satellite. We used AIRSAR toseparate open wetlands from mixed wetlands so thataccurate elevations measurements could be made. Wecompared SRTM elevations to ground-based measurementsof elevation and investigated their influence of theiraccuracy on a 900 square kilometer numerical flow model.These investigations indicate that seepage lakes, wetlands,and bogs are effective measurements of ground-waterelevations, but in flat-lying areas small errors in surfaceelevations can have significant impacts on groundwater flowmodels. Rigorous classification of remotely sensed surfacewater features is, therefore, critical to confident prediction ofgroundwater flow and biogeochemical transport. Radarband imaging is particularly useful tool locating suitablepoints of water elevation measurements in lakes, wetlands,and bogs.37