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

Pavelsky, Tamlin M.Continuous River Width-Drainage AreaRelationships in the Yukon River BasinPavelsky, Tamlin M. 1 ; Allen, George H. 11. Dept of Geological Sciences, University of NorthCarolina, Chapel Hill, NC, USAThrough their role in transporting water and sedimentfrom upland catchments to coastal oceans, rivers play a keyrole in organizing landscapes and represent a major link inthe global hydrologic cycle. River form varies widely, anddifferent characteristics reflect variations in discharge,substrate, climate, and human impacts. Studies of therelationship between fluvial form and discharge (orcatchment area, which is often substituted) have beenconducted since at least the early 1950s, with statisticalrelationships between discharge and river depth, width, andvelocity encapsulated in the hydraulic geometry framework.However, large-scale examinations of river form have beenlimited by a lack of data, and most prior studies havefocused on discrete cross-sections surveyed on the ground oron descriptions of network form (i.e. stream order) ratherthan continuous river morphology. More recently, satelliteremote sensing has been used to study river form over largerscales, without the need for ground-based surveying. To thispoint, however, studies of river form from space have largelyfocused on individual river reaches or sets of discrete crosssectionsrather than measuring fluvial form continuouslyover entire large river basins. In this study, we use theRivWidth software tool(http://www.unc.edu/~pavelsky/Pavelsky/RivWidth.html) tocontinuously map river widths from 30 m Landsat imageryfor all rivers wider than ~50m in the Yukon River Basin ofCanada and Alaska. The Yukon basin was selected because itis almost entirely free of direct human influence on riverform, while also containing a wide range of different channelplanforms. The resulting map of river widths is then linkedto a map of catchment area derived from the Hydro1Kdigital elevation dataset, allowing width and catchment areato be continuously compared across an entire large riverbasin for the first time. From these linked datasets, weevaluate the consistency of width-catchment arearelationships over the entire basin and compare individualsub-basins with different characteristics including sedimentload, permafrost extent, and annual precipitation. Inaddition, the width dataset developed here provides a firstmeasure of which rivers within the Yukon Basin will besampled by the NASA/CNES Surface Water and OceanTopography (SWOT) satellite mission. One of SWOT’s majorgoals is the provision of discharge estimates for all riverswider than 100 m, globally, yet the extent and locations ofthese rivers remains poorly constrained. We demonstrate theability of RivWidth measurements to estimate SWOTsampling extent over larger river basins such as the Yukon.Peters-Lidard, Christa D.The Impact of AMSR-E Soil Moisture Assimilationon Evapotranspiration EstimationPeters-Lidard, Christa D. 1 ; Kumar, Sujay 2, 1 ; Mocko, David 2, 1 ;Tian, Yudong 3, 11. Hydrological Sciences Laboratory, NASA/GSFC Code 617,Greenbelt, MD, USA2. SAIC, Beltsville, MD, USA3. ESSIC, University of Maryland, College Park, MD, USAAn assessment of ET estimates for current LDASsystems is provided along with current research thatdemonstrates improvement in LSM ET estimates due toassimilating satellite-based soil moisture products. Using theEnsemble Kalman Filter in the Land Information System, weassimilate both NASA and Land Parameter Retrieval Model(LPRM) soil moisture products into the Noah LSM Version3.2 with the North American LDAS phase 2 (NLDAS-2)forcing to mimic the NLDAS-2 configuration. Throughcomparisons with two global reference ET products, onebased on interpolated flux tower data and one from a newsatellite ET algorithm, over the NLDAS2 domain, wedemonstrate improvement in ET estimates only whenassimilating the LPRM soil moisture product.http://lis.gsfc.nasa.govPipunic, RobertImpacts of satellite surface soil moistureassimilation on modelled root zone soil moistureand ET over a six year period: Assessment across anin-situ soil moisture monitoring network, Murray-Darling Basin, AustraliaPipunic, Robert 1 ; Ryu, Dongryeol 1 ; Walker, Jeffrey 21. Department of Infrastructure Engineering, TheUniversity of Melbourne, Parkville, VIC, Australia2. Department of Civil Engineering, Monash University,Clayton, VIC, AustraliaThe importance of root zone soil moisture is recognisedfor its role in partitioning rainfall between infiltration andrun-off, drainage to groundwater, and as a water storeaccessible to plant roots contributing to evapotranspiration.Thus accurate predictions of moisture content in the rootzone will have enormous benefit for land and watermanagement practices including agriculture, flood andweather forecasting. While this has been long known, it isstill very difficult to predict the soil moisture content ofdesired accuracies with spatially distributed Land SurfaceModels (LSMs), which becomes more challenging whenLSMs are run at