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

water in Mexico. In the last sixty years it has undergonecritical changes due to human activity that includevariations in the size of the lake, increase of suspendedsediments and chlorophyll content. Overlaid to thosevariations, we have recorded large seasonal changes insuspended sediments that favor the growth ofbacterioplankton on the surface of the lake Multispectralsatellite images (TMLandsat) from May and November2002 were processed to identify suspended sediments andchlorophyll on the Lake of Chapala. Processing includedatmospheric correction, edge enhancement to define thewater body borders, spectral enhancement and principalcomponent analysis. Image processing was efficient to coversimultaneously the whole water body and providedidentification of the suspended sediments and chlorophyllpresence. Results show high concentration of suspendedsediments in the dry season image (May, 2002) and adramatic decrease in suspended sediments after the rainseason (November image) and an increase in chlorophyll dueto the high growth rate of the water hyacinth associatedwith the large input of fertilizers from the agricultural areasthat surround the lake tributaries as the Lerma river.Processed images show that higher chlorophyllconcentrations cluster on the eastern side of the lake drivenby the strong input of the Lerma River. The use of satellitemultispectral images allowed identification of seasonalchanges in suspended sediments and chlorophyll content,and defined the spatial relation of the chemical fertilizersinput from the lake tributaries with the water hyacinthplague that threatens to cause eutrophication of this waterbody.Mersel, Matthew K.Effects of Reach Averaging on Empirically-Based,Remotely-Sensed Estimates of River DepthMersel, Matthew K. 1 ; Smith, Laurence C. 1 ; Andreadis,Konstantinos M. 2 ; Durand, Michael T. 3, 41. Geography, UCLA, Los Angeles, CA, USA2. NASA Jet Propulsion Laboratory, Pasadena, CA, USA3. Byrd Polar Research Center, The Ohio State University,Columbus, OH, USA4. Earth Sciences, The Ohio State University, Columbus,OH, USAThe NASA Surface Water and Ocean Topography(SWOT) satellite mission, planned for launch in 2019, hasthe potential to greatly enhance our understanding of thespatial and temporal dynamics of rivers worldwide. Throughrepeat-pass measurements of water-surface elevation (WSE)and inundation width, SWOT will directly observe changesin flow for many of the world’s rivers (greater than ~100meters wide). However, because SWOT will only measurechannel bathymetry down to the lowest water levelencountered over the mission lifetime, true discharge willnot be directly measured and must thus be estimated.Perhaps the greatest limiting factor to accurate estimates ofriver discharge using SWOT measurements is the estimationof channel depth. An empirically-based method forestimating channel depth from synthetic SWOT retrievalsshows promise as a simple, yet effective method for remotelysensedriver depth approximation. The method exploits thederivatives of water-surface elevation and width in order toestimate average channel depth at “optimal” river locations.This approach, however, has previously been tested usingdiscrete datasets (i.e. cross-section datasets) that do not fullyrepresent the continuous type of data that SWOT willprovide. Using a gridded bathymetric dataset for the UpperMississippi River, we explore the extent to which thismethod for river depth estimation remains effective given amore complete knowledge of a river’s exposed channelgeometry (i.e. that portion of a river’s bathymetry that liesabove the water’s surface and is thus observable by SWOT).Furthermore, we explore the impact of reach-averaging ofremotely-sensed hydraulic variables (i.e. water-surfaceelevation and width) on this method. Initial results suggestthat reach-averaging of these variables up to approximately350m on the Upper Mississippi does not significantly reducethe accuracy of this depth estimation method.Miller, Norman L.Developing a High-Resolution Modeling andAssimilation Scheme for Terrestrial GroundwaterChangeMiller, Norman L. 1 ; Singh, Raj 1 ; Rubin, Yoram 21. Department of Geography, University of California,Berkeley, CA, USA2. Department of Civil and Environmental Engineering,University of California, Berkeley, CA, USATo date, remote sensed terrestrial water storage has beensuccessfully demonstrated and applied at scales of100,000km and coarser. However, water resource managersrequire much finer scales for monitoring local and basinscalechange. Hyper-resolution modeling at scales of 1kmand finer allows for significantly better representation of theeffects of spatial heterogeneity in topography, soils, andvegetation on hydrological dynamics. Such fine scale allowsfor the representation of processes that are sub grid to thecurrent generation of models, including slope and aspecteffects on surface incoming and reflected solar radiation, theeffects on snowmelt, soil moisture redistribution, andevapotranspiration. High-resolution models also enablebetter representation of channel processes and provide anindication of inundated areas, water depth in flooded areas,and indirectly the number of people impacted and criticalinfrastructure potentially at risk. In this study we develop aninnovative method for advancing high spatial resolutionsimulations of the terrestrial water budget with a particularfocus on terrestrial water storage variations through the useof new scaling arguments and assimilation of gravity data.The primary hypothesis is that the local water budget termscan be calculated with improved accuracy through theapplication of such scaling and assimilation methods. Wehave begun to use new methods to run the NCARCommunity Land Model version 4 (CLM4.0) at high (900m)and very high resolution (90m) for an east-west transect100