evolution of the western amazon lowland relief impact of andean foreland dynamics the congruency in the depositional origin and age of the uppermost sedimentary strata forming non flooded rainforest ground terra firme in the western and central amazon lowlands is a much debated subject here we conclude from the study of remote sensing imagery that active andean foreland dynamics have played a major role in the evolution of the plio pleistocene fluvial landscape in the western amazon foreland dynamics have resulted in a terra firme composed of late tertiary alluvium and younger alluvial terraces and plains in peru thermoluminescence and 14c dating show local aggradation of this younger alluvium between 180 and 30 ka the documented high age heterogeneity of the terra firme has implications for considerations of the biogeography of the amazon forest

reach scale floodplain inundation dynamics observed using airborne synthetic aperture radar imagery data analysis and modelling summary in this paper we use an airborne synthetic aperture radar to map river flood inundation synoptically at fine spatial resolution 1 2 m along a 16 km reach of the river severn west central england images were obtained at four times through a large flood event between 8th and 17th november 2000 and processed using a statistical active contour algorithm to yield the flood shoreline at each time intersection of these data with a high vertical accuracy survey of floodplain topography obtained from airborne laser altimetry permitted the calculation of dynamic changes in inundated area total reach storage and rates of reach dewatering in addition comparison of the data to gauged flow rates the measured floodplain topography and map data giving the location of embankments and drainage channels on the floodplain yields new insights into the factors controlling the development of inundation patterns at a variety of scales finally the data were used to assess the performance of a simple two dimensional flood inundation model lisflood fp and allows us for the first time to validate the dynamic performance of the model this process is shown to give new information into structural weaknesses of the model and suggests possible future developments including the incorporation of a better description of floodplain hydrological processes in the hydraulic model to represent more accurately the dewatering of the floodplain

geomorphology and ecosystems challenges and keys for success in bridging disciplines geomorphology plays a fundamental role in controlling many ecosystem processes and in turn ecosystems can have a profound influence on many geomorphic forms and processes over the past few decades a proliferation of research has developed at the interface of geomorphology and ecosystems ecology the 2005 binghamton symposium brought together some of the leading researchers from both communities to address these critical interfaces between the disciplines this paper reviews some of the aspects of the disciplines of geomorphology and ecosystems ecology and the papers presented at the symposium the papers in this volume illustrate the current status of the disciplines the difficulties in bridging the disciplines and the issues that are emerging as research priorities

a petrologic comparison of triassic plutonism in the san gabriel and mule mountains southern california triassic magmatism in the southwest u s cordillera forms a semicontinuous magmatic arc extending from northwestern nevada to southeastern california quartz monzodioritic and quartz monzonitic rocks and associated diorites and granites are widespread in southeastern california and we suggest that these rocks represent exposure of a structurally deeper part of the triassic arc where it was emplaced into comparatively thick proterozoic crust elemental and isotopic data suggest that triassic quartz monzodiorites and quartz monzonites in the mule and san gabriel mountains were derived from a relatively undepleted nonradiogenic mafic lithospheric source with virtually no upper crustal interaction very limited data for associated triassic diorites indicate a wide range in composition and a surprisingly radiogenic isotopic signature younger triassic granites record a strong geochemical signature of interaction with continental crust including inherited zircon and high initial sr ratios but comparatively less radiogenic pb isotopic compositions the major and trace element geochemistry of late triassic plutonic rocks in southeastern california is similar in many respects to alkalic components of the triassic arc in the mojave desert however contemporaneous rocks farther north have a calc alkalic signature perhaps reflecting the variation in age and composition of lithosphere across which the triassic arc was constructed

channel widening downstream of valley gorges influenced by flood frequency and floodplain roughness mountain fronts are the locus of significant variations in river width characterized by narrow bedrock gorges opening to wider unconfined alluvial rivers that are often braided the contribution of the abrupt change in river valley confinement in modulating the long term transport capacity and the resulting equilibrium channel width has never been considered here we use a numerical model integrating the full frequency magnitude distribution of streamflow to explore the long term bedload transport capacity of idealized confined and unconfined channels both single thread and braided the model predicts a significant transport capacity loss for a single channel of constant width at the transition between confined gorges and unconfined floodplains that is slightly reduced when floodplain vegetation is present because the total transport capacity of a single thread channel systematically decreases with channel width in a stochastic framework only narrower unconfined channels could compensate for the loss of confinement this prediction contradicts observations of widening ratios ranging from three to eight downstream of gorges in various world rivers we resolve this inconsistency by demonstrating that a braided river made of narrow channels inset in a wide floodplain can maintain the total bedload transport capacity downstream of gorges by increasing the range of competent discharges we also show that riparian vegetation may only enhance bedload transport capacity for highly variable discharge regimes and discuss the relevance of various definitions of representative discharges these results point to the previously unrecognized role of valley confinement in modulating the sediment transport capacity of rivers

efficient incorporation of channel cross section geometry uncertainty into regional and global scale flood inundation models this paper investigates the challenge of representing structural differences in river channel cross section geometry for regional to global scale river hydraulic models and the effect this can have on simulations of wave dynamics classically channel geometry is defined using data yet at larger scales the necessary information and model structures do not exist to take this approach we therefore propose a fundamentally different approach where the structural uncertainty in channel geometry is represented using a simple parameterisation which could then be estimated through calibration or data assimilation this paper first outlines the development of a computationally efficient numerical scheme to represent generalised channel shapes using a single parameter which is then validated using a simple straight channel test case and shown to predict wetted perimeter to within 2 for the channels tested an application to the river severn uk is also presented along with an analysis of model sensitivity to channel shape depth and friction the channel shape parameter was shown to improve model simulations of river level particularly for more physically plausible channel roughness and depth parameter ranges calibrating channel manning s coefficient in a rectangular channel provided similar water level simulation accuracy in terms of nash sutcliffe efficiency to a model where friction and shape or depth were calibrated however the calibrated manning coefficient in the rectangular channel model was 2 3 greater than the likely physically realistic value for this reach and this erroneously slowed wave propagation times through the reach by several hours therefore for large scale models applied in data sparse areas calibrating channel depth and or shape may be preferable to assuming a rectangular geometry and calibrating friction alone

wetland mapping in the congo basin using optical and radar remotely sensed data and derived topographical indices article i nfo this study reports results of a classification tree approach to mapping the wetlands of the congo basin focusing on the cuvette centrale of the congo river watershed an area of 1 176 000 km 2 regional expert knowledge was used to train passive optical remotely sensed imagery of the landsat thematic mapper tm and enhanced thematic mapper plus etm sensors jers 1 active radar l band imagery and topographical indices derived from 3 arc sec elevation data of the shuttle radar topography mission srtm all data inputs were resampled to a common 57 m resolution grid a classification tree bagging procedure was employed to produce a final map of per grid cell wetland probability thirty bagged trees were ranked and the median result was selected to produce the final wetland probability map thresholding the probability map at 0 5 yielded a proportion of wetland cover for the study area of 32 equivalent to 360 000 km 2 wetlands predominate in the carpe lake tele lake tumba landscape located in the western part of the democratic republic of the congo and the south eastern republic of congo where they constitute 56 of the landscape local topography depicting relative elevation for sub catchments proved to be the most valuable discriminator of wetland cover however all sources of information i e optical radar and topography featured prominently in contributing to the classification tree procedure reinforcing the idea that multi source data are useful in the characterization of wetland land cover the method employed freely available data and a fully automated process except for training data collection comparisons to existing maps and in situ field observations indicate improvements compared to previous efforts

simple spatially distributed models for predicting flood inundation a review abstract in this paper we review recent progress in the use of reduced complexity models for predicting floodplain inundation we review the theoretical basis for modelling floodplain flow with simplified hydraulic treatments based on a dimensional analysis of the one dimensional shallow water equations we then review how such schemes can be applied in practice and consider issues of space discretization time discretization and model parameterisation before going on to consider model assessment procedures we show that a key advantage of reduced complexity codes is that they force modellers to think about the minimum process representation necessary to predict particular quantities and act as a check on any tendency to reductionism at the same time however the use compared to standard hydraulic codes of strong simplifying assumptions requires us to also address the question how simple can a model be and still be physically realistic we show that by making explicit this debate about acceptable levels of abstraction reduced complexity codes allow progress to be made in addressing a number of long standing debates in hydraulics

remote sensing of floodplain geomorphology as a surrogate for biodiversity in a tropical river system madre de dios peru the complex floodplains of large rivers offer a striking example of how geomorphology by dictating patterns in the frequency and duration of soil saturation and surface flooding influences ecosystem structure and function this study draws on multiple sources of data from remote sensing together with ground observations and water sampling to distinguish floodplain ecosystems in the madre de dios river a tributary of the amazon river in peru this remote tropical river meanders across sub andean alluvial deposits in a tectonically active region and creates floodplain surfaces of varying ages including terraces that are above the reach of present day river floods data from landsat etm optical multispectral jers 1 l band radar and the shuttle radar topography mission c band interferometric digital elevation models were integrated in an object oriented image analysis approach to distinguish five classes of floodplain vegetation vegetation classes generally correspond with successional age and reflect the activity of the riverine meander belt stage data for the river show erratic fluctuations and an annual range exceeding 8 m but the maximum depth of floodplain inundation varied from 1 m close to the river to approximately 0 1 m on more elevated terraces the major ion composition of standing waters on the floodplain during the dry season indicated the importance of emergence of local groundwater in maintaining saturated soils particularly further from the river where backswamp vegetation is distinct and includes palm swamps thus a hydrological continuum exists from deep but sporadic river inundation near the river to constant soil saturation by groundwater emergence in distal backswamps reflecting the geomorphological origin and age of the floodplain deposits this hydrogeomorphic continuum results in fundamental ecological differences the exceptionally rich biodiversity of the sub andean region may be ascribed in part to the enhanced biodiversity associated with fluvial geomorphological features and thus conservation planning must account for the diverse landforms created by fluvial dynamics

a simple raster based model for flood inundation simulation in this paper the development of a new model for simulating flood inundation is outlined the model is designed to operate with high resolution raster digital elevation models which are becoming increasingly available for many lowland floodplain rivers and is based on what we hypothesise to be the simplest possible process representation capable of simulating dynamic flood inundation this consists of a one dimensional kinematic wave approximation for channel flow solved using an explicit finite difference scheme and a two dimensional diffusion wave representation of floodplain flow the model is applied to a 35 km reach of the river meuse in the netherlands using only published data sources and used to simulate a large flood event that occurred in january 1995 this event was chosen as air photo and synthetic aperture radar sar data for flood inundation extent are available to enable rigorous validation of the developed model 100 50 and 25 m resolution models were constructed and compared to two other inundation prediction techniques a planar approximation to the free surface and a relatively coarse resolution two dimensional finite element scheme the model developed in this paper outperforms both the simpler and more complex process representations with the best fit simulation correctly predicting 81 9 of inundated and non inundated areas this compares with 69 5 for the best fit planar surface and 63 8 for the best fit finite element code however when applied solely to the 7 km of river below the upstream gauging station at borgharen the planar model performs almost as well 83 7 correct as the raster model 85 5 correct this is due to the proximity of the gauge which acts as a control point for construction of the planar surface and the fact that here low lying areas of the floodplain are hydraulically connected to the channel importantly though it is impossible to generalise such application rules and thus we cannot specify a priori where the planar approximation will work simulations also indicate that for this event at least dynamic effects are relatively unimportant for prediction of peak inundation lastly consideration of errors in typically available gauging station and inundation extent data shows the raster based model to be close to the current prediction limit for this class of problem q 2000 elsevier science b v all rights reserved

volcanic eruptions on mid ocean ridges new evidence from the superfast spreading east pacific rise 17 19 s uniform sediment cover were recovered from lava that buries older faulted terrain the boundary in lava composition coincides with a change in depth to the top of an axial magma lens seismic reflector consistent with magmas from two separate reservoirs being erupted in the same event chemical compositions from throughout the area indicate that lavas with identical compositions can be emplaced in separate volcanic eruptions within individual segments a comparison of our results to global data on submarine mid ocean ridge eruptions suggests consistent dependencies of erupted volume activated fissure lengths and chemical heterogeneity with spreading rate consistent with expected eruptive characteristics from ridges with contrasting thermal properties and magma reservoir depths index terms 3035 marine geology and geophysics midocean ridge processes 8414 volcanology eruption mechanisms 8439 volcanology physics and chemistry of magma bodies 3655 mineralogy and petrology major element composition keywords lava flow chemical heterogeneity erupted volume lava morphology side scan sonar

plutonic lithics in ignimbrites of taupo volcanic zone new zealand sources and conditions of crystallisation abstract plutonic rock fragments occur as rare accessory lithics within some of the ignimbrites erupted from calderas and caldera complexes in central taupo volcanic zone tvz new zealand the two main suites of plutonic lithics are 1 medium to fine grained granitoids and 2 fine grained dolerites and microdiorites the granitoids are mostly medium grained rocks with both equigranular and granophyric intergrowth textures the latter indicating rapid crystallisation at shallow crustal levels biotite is the predominant mafic phase in most granitoid samples although rare hornblende and orthopyroxene bearing granitoids also occur glass occurs in some granitoid samples from rotoiti ignimbrite indicating that these samples were incompletely crystallised prior to eruption dolerite and microdiorite fragments typically contain abundant hornblende and up to 10 vesicular interstitial glass sio2 abundances in the granitoids range between 70 3 and 77 9 they are weakly metaluminous to weakly peraluminous and show an enrichment in large ion lithophile lil elements rb k ba and a depletion in nb relative to morb similar to recent tvz rhyolitic volcanic rocks chemically and petrographically the granitoids fall into two distinct groups high sr granodiorites 120 205 ppm sr and chemically more evolved low sr monzogranites 26 65 ppm sr with an apparent compositional gap between the two eu eu anomalies and strong correlations between al2o3 cao and sr indicate that compositional variation between the two granitoid groups is dominantly controlled by plagioclase fractionation the high and low sr groups coincide with the highest and lowest sr concentrations observed in tvz rhyolites ree data and sr nd pb and o isotope ratios for granitoids are comparable to published data for tvz rhyolites and consequently they are considered to represent crystallised portions of zoned silicic magma chambers associated with quaternary tvz volcanic activity and not fragments of older pre tvz basement most granitoids are regarded as comagmatic with their host ignimbrites but those from rotoiti ignimbrite have different mineral assemblages and whole rock chemistry to the host ignimbrite these fragments appear to be incompletely crystallised portions of an earlier magma system possibly the same system that generated the matahina ignimbrite dolerites and microdiorites are geochemically similar to evolved high alumina basalts erupted from the central tvz and are considered to be intrusive equivalents

the morphology and surface processes of comet 19 p borrelly the flyby of the nucleus of the comet 19p borrelly by the deep space 1 spacecraft produced the best views to date of the surface of these interesting objects it transformed borrelly from an astronomical object shrouded in coma of gas and dust into a geological object with complex surface processes and a rich history of erosion and landform evolution based on analysis of the highest resolution images stereo images photometry and albedo we have mapped four major morphological units and four terrain features the morphological units are named dark spots mottled terrain mesas and smooth terrain the features are named ridges troughs pits and hills in strong contrast to asteroids unambiguous impact craters were not observed on borrelly s surface because of the relatively short period of this comet surface erosion by volatile sublimation is in geologic terms a very active process the formation and the morphologies of units and features appear to be driven by differential rates of sublimation erosion erosional rates across the comet are probably controlled by solar energy input and the location of the subsolar point during perihelion differences in energy input may produce different varieties of sublimation erosional landforms the terrains on borrelly suggest that solar energy input could map directly into erosional processes and landforms

floodplain channel morphology and networks of the middle amazon river 1 floodplain channels are important components of river floodplain systems and are known to play a key role in hydrodynamic exchange and sediment transport the amazon floodplain exhibits complex networks of these channels and despite their potential importance to this globally important wetland system these floodplain channels are relatively unstudied the research presented here is the first systematic and detailed study of the network and morphologic characteristics of a large number of these channels in the middle reach of the central amazon river using analysis of data derived from landsat enhanced thematic mapper plus etm mosaic and field survey our findings show that the channels are ubiquitous their width varies widely and some of their characteristics can be fitted using power laws potentially much like the self similar or fractal like behavior hypothesized for other types of fluvial networks in all 96 of the floodplain channels are not wide enough to be represented well or at all in the 90 m shuttle radar topography mission data channel depths are tied closely to the local amplitude of the passing main river flood wave p value of 0 75 except where there are local runoff inputs which results in substantially deeper channels which provide preferential flow paths across the floodplain channel networks imply that areas of the floodplain function for large parts of the flood cycle as separate hydrogeomorphic land units here termed floodplain hydrological units fhus these hypothesized fhus also have distinct spatial and pattern characteristics and it is suggested here that their differences could provide the beginnings of a framework for understanding the detailed hydrodynamics of the floodplain in particular different types of fhus have differences in flood water source which will have important implications for biogeochemical studies of the wetlands

was the 2009 flood the most hazardous or the largest ever recorded in the amazon abstract floods are fundamental components of amazon nature and culture the large flood of 2009 however opened a new perspective on hazards and disasters in the amazon basin more than 238 000 residents from 38 municipalities were affected by floods along the amazon river and lower reaches of its tributaries never before has a flood in the amazon produced such a dramatic effect on the local population the magnitude of the disaster suggested it was the largest recorded amazon flood since the beginning of measurements in 1928 at obidos and that it could represent the largest recorded flood on earth a complex combination of atmospheric and hydrologic factors made the 2009 amazon flood the most hazardous it was the result of large scale and regional climatic events non typical mechanisms of flood transmission generating complex inter relations in time and space between the main system and the tributaries and recent urban growth of riverine cities without adequate planning our measurements at obidos however indicate that the 2009 flood was the highest recorded amazon stage but most likely not the largest water discharge we propose as well that the magnitude of the amazon floods at obidos has been overestimated for decades and that the available values of flood discharge have been a source of error for a multidisciplinary set of scientists developing climate and environmental modeling

surface processes recorded by rocks and soils on meridiani planum mars microscopic imager observations during opportunity s first three extended missions the microscopic imager mi on the mars exploration rover opportunity has returned images of mars with higher resolution than any previous camera system allowing detailed petrographic and sedimentological studies of the rocks and soils at the meridiani planum landing site designed to simulate a geologist s hand lens the mi is mounted on opportunity s instrument arm and can resolve objects 0 1 mm across or larger this paper provides an overview of mi operations data calibration and analysis of mi data returned during the first 900 sols mars days of the opportunity landed mission analyses of opportunity mi data have helped to resolve major questions about the origin of observed textures and features these studies support eolian sediment transport rather than impact surge processes as the dominant depositional mechanism for burns formation strata mi stereo observations of a rock outcrop near the rim of erebus crater support the previous interpretation of similar sedimentary structures in eagle crater as being formed by surficial flow of liquid water well sorted spherules dominate ripple surfaces on the meridiani plains and the size of spherules between ripples decreases by about 1 mm from north to south along opportunity s traverse between endurance and erebus craters

relationship of soil properties to parent material and landscape position in eastern madre de dios peru abstract properties of soils in the eastern part of madre de dios peru were characterized and related to landscape position and parent material texture level uplands dissected side slopes and recent flood plains dominate the topography in this region soil textures vary from clayey to sandy depending on the texture of sedimentary materials from which each pedon formed parent material textural variation is a result of differences in the energy of the meandering rivers that deposited the ancient alluvium fourteen soil profiles were described and sampled in the field and analyzed in the laboratory data for eight soil profiles representative of the region are presented here the profiles include soils formed in both sandy and fine textured parent materials and soils with moisture status ranging from well drained to poorly drained soil moisture conditions vary with position on the landscape such that as distance from streams increases average depth to the fluctuating water table decreases redoximorphic features are present in all mineral soils the average depth to redoximorphic features is least in locations furthest from streams soils in landscape positions that are poorly or somewhat poorly drained contain significant amounts of plinthite in all soils kaolinite is the dominant mineral in the

adjustment of a spaceborne dem for use in floodplain hydrodynamic modeling summary precise digital elevation models dems are required for the accurate modeling of floodplain hydrodynamics the accuracy of currently available spaceborne dems however is hindered by a variety of errors which reduce the flow connectivity between river channels and the surrounding floodplains here we introduce a new algorithm for adjusting a spaceborne dem which utilizes the information from a prescribed drainage networks dataset the algorithm is designed to remove all the pits in the spaceborne dem caused by vegetation canopies sub pixel sized structures and random radar speckles while minimizing the amount of modification required for removing the pits the proposed algorithm was applied to the srtm3 dem with reference to the drainage network information in the hydrosheds flow direction map with consideration of the systematic errors in the srmt3 dem small channels connecting floodplains were successfully implemented into the adjusted dem the accuracy of the adjusted dem was validated using hydrodynamic simulations with the lisflood fp model in a middle reach of the amazon river the simulated water surface elevations and flooded areas with the adjusted dem shows better agreement to observation data when compared to the results from the original srtm3 dem the flow connectivity ensured by the dem adjustment algorithm is found to be essential for representing realistic water exchanges between river channels and floodplains in hydrodynamics modeling

geochronology of the proterozoic basement of southwesternmost north america and the origin and evolution of the mojave crustal province the proterozoic baldwin gneiss in the central transverse ranges of southern california a part of the mojave crustal province is composed of quartzofeldspathic gneiss and schist augen and granitic gneiss trondhjemite gneiss and minor quartzite amphibolite metagabbro and metapyroxenite sensitive high resolution ion microprobe shrimp data indicate that augen and granitic gneisses comprise a magmatic arc intrusive suite emplaced between 1783 12 and 1675 19 ma adjacent to or through thinned archean crust high u th rims on zircons in most samples suggest an early metamorphic event at 1741 ma but peak amphibolite facies metamorphism and penetrative west vergent deformation occurred after 1675 ma the baldwin gneiss is part of a regional allochthon emplaced by west vergent deformation over a proterozoic shelf slope sequence joshua tree terrane we hypothesize that emplacement of this regional allochthon occurred during a late early or middle proterozoic arc continent collision along the western margin of laurentia

the hydro geomorphologic complexity of the lower amazon river floodplain and hydrological connectivity assessed by remote sensing and field control abstract hydrological connectivity processes along the lower amazon river floodplain at lago miratuba floodplain lmf were analyzed based on remote sensing and field measurements connectivity processes are related to 12 geomorphic sub units of the floodplain that are interconnected at different stage thresholds through channelized and overbank flow paths while lakes act as reservoirs for flood waters local rainfall and water table saturation seepage hydrological connectivity processes along the floodplain happen through complex internal routings of water flows over space and time mainly along floodplain channels and breached levees the contribution of local recharge mainly rainfall was decoupled from river recharge river hydrological connection to floodplain because precipitations and local runoff also recharge the floodplain the hydrological connectivity of the 12 geomorphic units varied significantly from each other because the inundation and the floodplain connections with the river were initiated at specific river stage thresholds for each sub unit an interesting finding is that connections with the river for all units were initiated through channelized flows below the bankfull stage of the amazon river the connectivity processes over different geomorphic units are also not correlated with their minimum distance shortest lines from the river this implies that a flood pulse model largely concerned with lateral connectivity mostly through overbank diffusion only partially explains the complex hydrological connectivity processes at a regional scale along the complex lower amazon river floodplain thus for hydrological connectivity assessments in the amazon river floodplain reach by reach scale studies have to be carried out relating the hydro geomorphologic processes channelized flow routing paths overbank diffusion and local recharge to the internal geomorphic variability and complexity of the floodplain

a high accuracy map of global terrain elevations spaceborne digital elevation models dems are a fundamental input for many geoscience studies but they still include nonnegligible height errors here we introduce a high accuracy global dem at 3 resolution 90 m at the equator by eliminating major error components from existing dems we separated absolute bias stripe noise speckle noise and tree height bias using multiple satellite data sets and filtering techniques after the error removal land areas mapped with 2 m or better vertical accuracy were increased from 39 to 58 significant improvements were found in flat regions where height errors larger than topography variability and landscapes such as river networks and hill valley structures became clearly represented we found the topography slope of previous dems was largely distorted in most of world major floodplains e g ganges nile niger and mekong and swamp forests e g amazon congo and vasyugan the newly developed dem will enhance many geoscience applications which are terrain dependent

high resolution mapping of floodplain topography from space a case study in the amazon abstract terrain elevation is essential for land management navigation and earth science applications remote sensing advancements have led to an increase in the availability of a range of digital elevation models with global to quasi global land coverage however the generation of these models in water bodies requires specialized approaches such as the delimitation of the shorelines isobaths of lakes over time therefore the processing costs are high in complex areas with many lakes currently there is no systematic topographic mapping of lakes and channels in large and complex floodplains using remote sensing data we present here the first high resolution topographic mapping 30 m of the non forested portion of the middle lower amazon floodplain using a new method based on in situ amazon river water levels and a flood frequency map derived from the landsat global surface water dataset validation using locally derived bathymetry showed a root mean square error rmse of 0 89 m for floodplain elevation and a good representation of spatial patterns with pearson s correlation coefficient of 0 77 our approach for improving topographic representation in open water areas is an alternative to srtm3 dem or merit dem which represents these areas as a flat surface we also generated the amazon river bathymetry using nautical charts from the brazilian navy average rmse of 7 5 m and bias of 5 m and floodplain depths maps corresponding to the high and low water periods of the river flood wave the results show that the storage volume in the open water floodplain varies 104 3 km3 on average each year from 11 9 km3 in low water to 116 2 km3 in high water the method can be applied to any temporarily flooded area to provide the often missing underwater digital topographic data required for hydrological ecological and geomorphological studies the data set developed in this study can be found at https doi org 10 17632 vn599y9szb 1

groundwater discharge into an estuary using spatially distributed radon time series and radium isotopes summary quantifying groundwater discharge remains a challenge due to its large temporal and spatial variability here we quantify groundwater discharge into a small estuary using radon 222rn and radium isotopes 223ra and 224ra high temporal resolution 30 min time steps radon observations at 4 time series stations were used to determine where groundwater discharge is prevalent in the estuary and to reduce mass balance model uncertainties a three endmember mixing model was developed based on short lived radium isotopes sampled at a single location to separate the shallow saline and deep fresh sources of the discharging groundwater the results show that using multiple 222rn time series stations decreased the overall uncertainty of groundwater discharge estimates from about 41 to 23 the radon derived groundwater flux was 56 13 and 35 12 cm d 1 in wet and dry conditions respectively the spatially distributed stations detected a well defined small area located four kilometers upstream from the mouth of the estuary as a groundwater discharging hotspot estimates based on a 223ra and 224ra mass balance resulted in groundwater discharge estimates of 65 18 and 84 48 cm d 1 in the wet and 18 5 and 20 6 cm d 1 in the dry the mixing model revealed contrasting results for deep vs fresh groundwater contribution in wet and dry conditions in wet conditions deep fresh groundwater discharging into the estuary contributed 65 compared to the shallow saline groundwater 35 while during dry conditions a larger contribution 80 was related to shallow groundwater a comprehensive spatial and temporal sampling strategy can produce groundwater discharge estimates with lower uncertainty and provides additional insight on where groundwater enters surface waters

detection and mapping of the geomorphic effects of flooding using uav photogrammetry in this paper we present a novel technique for the objective detection of the geomorphological effects of flooding in riverbeds and floodplains using imagery acquired by unmanned aerial vehicles uavs also known as drones equipped with an panchromatic camera the proposed method is based on the fusion of the two key data products of uav photogrammetry the digital elevation model dem and the orthoimage as well as derived qualitative information which together serve as the basis for object based segmentation and the supervised classification of fluvial forms the orthoimage is used to calculate textural features enabling detection of the structural properties of the image area and supporting the differentiation of features with similar spectral responses but different surface structures the dem is used to derive a flood depth model and the terrain ruggedness index supporting the detection of bank erosion all the newly derived information layers are merged with the orthoimage to form a multi band data set which is used for object based segmentation and the supervised classification of key fluvial forms resulting from flooding i e fresh and old gravel accumulations sand accumulations and bank erosion the method was tested on the effects of a snowmelt flood that occurred in december 2015 in a montane stream in the sumava mountains czech republic central europe a multi rotor uav was used to collect images of a 1 km long and 200 m wide stretch of meandering stream with fresh traces of fluvial activity the performed segmentation and classification proved that the fusion of 2d and 3d data with the derived qualitative layers significantly enhanced the reliability of the fluvial form detection process the assessment accuracy for all of the detected classes exceeded 90 the proposed technique proved its potential for application in rapid mapping and detection of the geomorphological effects of flooding

floodplain complexity and surface metrics influences of scale and geomorphology abstract many studies of fluvial geomorphology and landscape ecology examine a single river or landscape thus lack generality making it difficult to develop a general understanding of the linkages between landscape patterns and larger scale driving variables we examined the spatial complexity of eight floodplain surfaces in widely different geographic settings and determined how patterns measured at different scales relate to different environmental drivers floodplain surface complexity is defined as having highly variable surface conditions that are also highly organised in space these two components of floodplain surface complexity were measured across multiple sampling scales from lidar derived dems the surface character and variability of each floodplain were measured using four surface metrics namely standard deviation skewness coefficient of variation and standard deviation of curvature from a series of moving window analyses ranging from 50 to 1000 m in radius the spatial organisation of each floodplain surface was measured using spatial correlograms of the four surface metrics surface character variability and spatial organisation differed among the eight floodplains and random fragmented highly patchy and simple gradient spatial patterns were exhibited depending upon the metric and window size differences in surface character and variability among the floodplains became statistically stronger with increasing sampling scale window size as did their associations with environmental variables sediment yield was consistently associated with differences in surface character and variability as were flow discharge and variability at smaller sampling scales floodplain width was associated with differences in the spatial organisation of surface conditions at smaller sampling scales while valley slope was weakly associated with differences in spatial organisation at larger scales a comparison of floodplain landscape patterns measured at different scales would improve our understanding of the role that different environmental variables play at different scales and in different geomorphic settings

chapter 3 mid crustal emplacement ofmesozoic plutons san gabriel mountains california and implicationsfor the geologic history of the san gabriel terrane

a new procedure for gridding elevation and stream line data with automatic removal of spurious pits abstract a morphological approach to the interpolation of regular grid digital elevation models dems from surface specific elevation data points and selected stream lines is described the approach has given rise to a computationally efficient interpolation procedure which couples the minimization of a terrain specific roughness penalty with an automatic drainage enforcement algorithm the drainage enforcement algorithm removes spurious sinks or pits yielding dems which may be used to advantage in hydrological process studies the drainage enforcement algorithm has also been found to significantly increase the accuracy of dems interpolated from sparse but well chosen surface specific elevation data moreover it facilitates the detection of errors in elevation data that would not be detected by more conventional statistical means and forms a sound physical basis for cartographic generalization

holocene floodplain lake sediments in the amazon 14c dating and palaeoecological use abstract the holocene biostratigraphic record of amazon lowland rain forests is fragmentary and is based on restricted number of cores the majority representing sedimentation in a floodplain environment these biostratigraphic data have often been interpreted as demonstrating climatic oscillation between wetter and drier conditions and the subsequent vegetation changes here we survey and 14c date a further six western amazon floodplain lakes and examine their fluvially controlled sedimentation processes the lakes which are of the cutoff type are located along the rivers manu tambopata and amazon solimoes in the peruvian amazon lowlands all the lakes cored are under the influence of current overbank sedimentation of the parent suspension rich whitewater rivers and receive an annual fill of allochthonous inorganic suspension during the flood most of the cores collected were rich in minerogenic sediments gyttja clay loss on ignition we think that the observed bias towards older 14c ages documented in the gyttja clays is caused by the high proportion of old fine particulate organic matter being recirculated and resedimented within the suspension load the strong fluvial control of lake sedimentation and the unreliability of the 14c dates from the amazon suspension rich floodplains call for caution in palaeoecological interpretation furthermore owing to the low number of within lake replicate cores in the amazon holocene stratigraphy analyses we consider the postulated holocene climatic oscillation schemes to be tentative only

validation of a full hydrodynamic model for large scale hydrologic modelling in the amazon a key aspect of large river basins partially neglected in large scale hydrological models is river hydrodynamics large scale hydrologic models normally simulate river hydrodynamics using simplified models that do not represent aspects such as backwater effects and flood inundation key factors for some of the largest rivers of the world such as the amazon in a previous paper we have described a large scale hydrodynamic approach resultant from an improvement of the mgb iph hydrological model it uses full saint venant equations a simple storage model for flood inundation and gis based algorithms to extract model parameters from digital elevation models in the present paper we evaluate this model in the solimoes river basin discharge results were validated using 18 stream gauges showing that the model is accurate it represents the large delay and attenuation of flood waves in the solimoes basin while simplified models represented here by muskingum cunge provide hydrographs are wrongly noisy and in advance validation against 35 stream gauges shows that the model is able to simulate observed water levels with accuracy representing their amplitude of variation and timing the model performs better in large rivers and errors concentrate in small rivers possibly due to uncertainty in river geometry the validation of flood extent results using remote sensing estimates also shows that the model accuracy is comparable to other flood inundation modelling studies results show that i river floodplain water exchange and storage and ii backwater effects play an important role for the amazon river basin hydrodynamics copyright 2011 john wiley sons ltd

interpretation of crustal seismic velocities in the san gabriel mojave region southern california the increased concern over seismic hazards in the los angeles region has created interest in the crustal structure and mechanical properties associated with faults like the sierra madre and san andreas this study presents the seismic properties of major lithologies found in the vicinity of the san andreas fault zone in order to correlate with the los angeles region seismic experiment lars e results scientists from the larse group have recently acquired high quality seismic data along three transects thirty nine rock samples were collected along the larse line i which trends ne sw across the central mojave desert and the san gabriel mountains these rock samples represent the following lithologies precambrian gneisses san gabriel anorthosite mesozoic granitic intrusives pelona schist mendenhall granulite gneisses and san andreas fault zone cataclasites the seismic properties were determined by measuring compressional and shear wave velocities as a function of confining pressure average compressional and shear wave velocities at 150 mpa show a wide range of values the mendenhall gneiss and the san gabriel anorthosite complex have high velocities 6 5 km s and 6 4 km s respectively the pelona schist the mojave granitic intrusives and the san andreas cataclasitic rocks have average velocities of 5 8 km s 5 2 km s and 5 1 km s respectively average densities range from 2320 kg m3 for fault zone cataclasites to 3100 kg m3 for a mendenhall granulite gneiss gneisses and schists show significant seismic anisotropy 5 20 due to preferred mineral orientation while most other rocks are nearly isotropic poisson s ratios range from a high of 0 29 in the san gabriel anorthosite to a low of 0 22 in the san gabriel gneiss comparison of the measured seismic properties with the larse velocity model allows interpretation of crustal structure in terms of rock compositions the upper crust southwest of the san andreas fault contains granitic intrusives gneisses and schists while under the mojave desert the upper crust is dominated by gneisses high velocities under the san gabriel mountains represent either lower crustal granulites or anorthosite the velocity decrease beneath the san andreas fault zone originates from minor amounts of cataclasite or the presence of low velocity lithologies such as pelona schist 1998 elsevier science b v all rights reserved

multi scale assessment of overflow driven lateral connectivity in floodplain and backwater channels using lidar imagery overflow driven lateral connectivity significantly influences the spatial distribution and diversity of floodplain habitats and biota proper understanding of lateral connectivity in floodplain and backwater channels is therefore critical for assessment of river quality and for targeting management or restoration actions in this study we present a methodological framework for spatial and temporal assessments of overflow driven lateral connectivity at two spatial scales bypass reach and backwater channel firstly we compute the relative elevations as well as overflow discharge duration and frequency using a simple raster based method that uses a lidar digital elevation model dem rating curves and streamflow time series subsequently we analyse the accuracy of this approach with respect to the accuracy of a dem and evaluate its further applications altogether four 10 km long bypass reaches and 11 backwater channels are analysed located along the rhone river corridor in france the results proved the precision of the method to be affected by the lidar dem accuracy which was on average more precise in a typically homogeneous floodplain setting rather than for backwater channel plugs with pronounced topographic complexity and usually riparian forest canopy amongst the four studied reaches bregnier cordon proved to have the greatest flooding dynamics followed by belley and chautagne the hydrological connectivity pattern of pierre benite differed significantly three longitudinal patterns of hydrological connectivity of backwater channels displayed stepwise advancement of the water the presented results can be used to assess ecological potential of floodplain habitats and their historic and prospective evolution through time copyright 2014 john wiley sons ltd

channel floodplain geomorphology along the solimoes amazon river brazil across the cratonic landscape of brazil the solimoes amazon river transports to its delta plain 1240 mt of suspended sediment derived from andean erosion and reworks another 3200 mt of floodplain sediments distribution of these sediments has resulted in a variable along stream pattern of geomorphology the upstream reaches are characterized by sediment erosion in the main channel and deposition in floodplain channels that are an order of magnitude smaller in discharge than the main channel sediment deposition in and migration of the floodplain channels erases oxbow lakes of the main channel and yields an intricate scroll bar topography that forms the boundaries of hundreds of long narrow lakes in contrast downstream reaches are characterized by channels restricted by stabilizing long term levee building and floodplain construction dominated by overbank deposition overbank deposition buries the scroll bar topography resulting in a flat floodplain covered by a patchwork of large more equant shallow lakes on the basis of estimated rates of recycling of floodplain sediments the modern floodplain of the brazilian amazon could have been recycled in 5000 yr and is recycled more rapidly in the upstream than the downstream reaches the cratonic interior is interrupted by structural arches that bound intracratonic basins four of these arches cross the valley of the main river system at intervals of several hundred kilometres and impart a tectonic imprint on the channel floodplain geomorphology at this spatial scale structural arches appear to exert a primary influence by promoting entrenchment of the river as it passes through zones of deformation thus restricting channel movement for example as the river crosses the purus arch the valley narrows to 20 km compared to an average of 45 km the water surface gradient decreases sediment is deposited and yet the rate of channel migration is negligible hence the effect of the arches is to create a landscape where on the spatial scale of hundreds of kilometres the river is confined and entrenched in its valley is straight and is relatively immobile local valley tilting apparently unrelated to the arch structures also imprints the geomorphology in particular a tilted valley in the upstream reaches appears to have caused avulsions which have left behind the only large scale oxbow type features on the brazilian amazon river floodplain

flooding dynamics on the lower amazon floodplain 1 hydraulic controls on water elevation inundation extent and river floodplain discharge 1 modeling the routing of flood waters across large floodplains is challenging because flows respond to dynamic hydraulic controls from complex geomorphology vegetation and multiple water sources in this study we analyzed the topographic and hydrologic controls of inundation dynamics of a large floodplain unit 2440 km2 along the lower amazon river we combined land topography derived from the shuttle radar topography mission srtm with underwater topography derived from an extensive echo sounding survey to generate a seamless digital elevation model dem floodplain inundation was simulated using lisflood fp which combines one dimensional river routing with two dimensional overland flow and a local hydrological model for the first time accurate simulation of filling and drainage of an amazon floodplain was achieved with quantification of changes in water elevation flooding extent and river floodplain exchange we examined the role of diffuse overbank versus channelized flows on river floodplain exchange diffuse overbank flows represent 93 of total river to floodplain discharge and 54 of floodplain to river discharge floodplain discharge during high water was four times higher than field observation values when the srtm v 4 dem with no correction was used for simulation because of a 4 4 m elevation bias originating from residual motion errors of the srtm interferometric baseline

exchanges of sediment between the flood plain and channel of the amazon river in brazil sediment transport through the brazilian sector of the amazon river valley a distance of 2010 km involves exchanges between the channel and the flood plain that in each direction exceed the annual flux of sediment out of the river at obidos 1200 mt yr 1 the exchanges occur through bank erosion bar deposition settling from diffuse overbank flow and sedimentation in flood plain channels we estimated the magnitude of these exchanges for each of 10 reaches of the valley and combined them with calculations of sediment transport into and out of the reaches based on sediment sampling and flow records to define a sediment budget for each reach residuals in the sediment budget of a reach include errors of estimation and erosion or deposition within the channel the annual supply of sediment entering the channel from bank erosion was estimated to average 1570 mt yr 1 1 3 the obidos flux and the amount transferred from channel transport to the bars 380 mt yr 1 and the flood plain 460 mt yr 1 in channelized flow 1230 mt yr 1 in diffuse overbank flow totaled 2070 mt yr 1 1 7 the obidos flux thus deposition on the bars and flood plain exceeded bank erosion by 500 mt yr 1 over a 10 16 yr period sampling and calculation of sediment loads in the channel indicate a net accumulation in the valley floor of approximately 200 mt yr 1 over 16 yr crudely validating the process based calculations of the sediment budget which in turn illuminate the physical controls on each exchange process another 300 400 mt yr 1 are deposited in a delta plain downstream of obidos the components of the sediment budget reflect hydrologic characteristics of the valley floor and geomorphic characteristics of the channel and flood plain which in turn are influenced by tectonic features of the amazon structural trough

chemical weathering response to tectonic forcing a soils perspective from the san gabriel mountains california abstract what controls the chemical weathering of soils in tectonically active landscapes recent field and modeling studies suggest that tectonic forcing and associated increases in erosion rates may either promote or hinder soil chemical weathering these competing trajectories are dependent on two primary controls the availability of fresh minerals and their residence time on the landsurface here we explore rates and extents of soil weathering in the san gabriel mountains of california where previous work has measured clear tectonic fingerprints on rates of long term exhumation hillslope erosion and landscape morphology we quantify chemical weathering across this landscape by elemental analysis of soils saprolites and bedrock on six sites that bracket the low gradient hillslopes of the relict upland plateau and the high gradient hillslopes at the margins of the tectonically driven incising landscape average chemical depletion fractions which measure weathering losses from soil relative to unweathered parent material decrease with increasing elevation and decreasing temperature reflecting a combination of climate influence and potential dust inputs from the mojave desert weathering fluxes from non dust affected sites with similar elevations climates and lithology correlate with both erosion rates and hillslope gradient on low gradient hillslopes 25 weathering intensities and rates both decrease as erosion rates increase and soils thin at the highest denudation rates 300 t km 2 y 1 saprolite production is outpaced and soils are produced directly from fractured rock these patterns are consistent with those predicted by a previously published model for denudation weathering relationships based on mineral weathering kinetics variable weathering extents in soils indicate that weathering in the sgm is largely kinetically limited this study is the first to quantify decreases in both rates and extents of soil chemical weathering with increasing erosion rates and suggests tectonic uplift in rapidly eroding and incising landscapes may not stimulate increased silicate weathering

simulating the surface waters of the amazon river basin impacts of new river geomorphic and flow parameterizations this paper describes the impacts of new river geomorphic and flow parameterizations on the simulated surface waters dynamics of the amazon river basin three major improvements to a hydrologic model are presented 1 the river flow velocity equation is expanded to be dependent on river sinuosity and friction in addition to gradient forces 2 equations defining the morphological characteristics of the river such as river height width and bankfull volume are derived from 31 622 measurements of river morphology and applied within the model 3 1 km resolution topographic data from the shuttle radar topography mission srtm are used to provide physically based fractional flooding of grid cells from a statistical representation of sub grid scale floodplain morphology the discharge and floodplain inundation of the amazon river is simulated for the period 1968 1998 validated against observations and compared with results from a previous version of the model these modifications result in considerable improvement in the simulations of the hydrological features of the amazon river system the major impact is that the average wet season flooded area on the amazon mainstem for the period 1983 1988 is now within 5 of satellite derived estimates of flooded area whereas the previous model overestimates the flooded area by about 80 the improvements are a consequence of the new empirical river geomorphologic functions and the srtm topography the new formulation of the flow velocity equation results in increased river velocity on the mainstem and major tributaries and a better correlation between the mean monthly simulated and observed discharge copyright 2007 john wiley sons ltd

ndvi patterns as indicator of morphodynamic activity in the middle parana river floodplain abstract this work assesses the performance of a 2000 2014 ndvi modis time series to identify areas of the parana river floodplain associated with different morphodynamic areas and hence ecological behavior from classification procedures we obtained six ndvi patterns p1 to p6 differing in their mean values standard deviation and seasonality the ndvi patterns are evidence of different situations in terms of elevation flood dynamics and vegetation physiognomies p1 represents water bodies p2 to p4 cover frequently flooded lowlands colonized by marshy vegetation and p5 and p6 are placed on middle and high elevations that are less flooded and also are covered by tall vegetation grassland and forest instead of differences among the six ndvi patterns they showed a spatial arrangement that allowed the identification of two parallel belts belt i formed by p2 to p4 is placed close to the parana river and its connected branches while belt ii formed by p5 and mainly p6 appears on the marginal floodplain far away from the main channels the spatial arrangement of the two belts is similar to limits followed by the morphodynamic areas of the parana fluvial system more than 60 of the surface covered by p2 and p5 corresponds to low morphodynamic areas while nearly 70 of p6 matches with high morphodynamic areas through their annual and interannual behavior spatial arrangement and relationship with morphodynamic areas the ndvi patterns allow the interpretation of lateral organization of the parana river floodplain this paper exploits the potential of time series of ndvi to understand from a synoptic point of view the floodplain dynamics by capturing the seasonal and interannual variability of vegetation physiognomies and hydrosedimentological regime along and across the floodplain

retro modeling the middle mississippi river summary a one dimensional 1 d unsteady flow retro model was developed using historic c 1900 hydrologic and geospatial data and implemented using hec ras the objective of this investigation was to create a 1 d unsteady flow model for the middle mississippi river for the beginning of the 20th century in order to assess the magnitude and types of changes in flood stages associated with 20th century river engineering the retro model was constructed from survey data dating to 1888 1889 and hydrologic data from 1900 to 1904 the late 19th century survey data was supplemented by a modern high resolution dem used to fill gaps in the historic data land cover data recorded during this historic survey was used to establish floodplain roughness values based on published manning s n for the various land cover types and these roughness values were then adjusted to calibrate the model comparison of the retro model results with the 2004 upper mississippi river system flow frequency study umrsffs flood stages showed increases in flood stages of 2 3 4 7 m for large events 50 year recurrence interval these results confirm previous research results showing large scale reductions in flood conveyance on the middle mississippi during the 20th century increased roughness of the floodway coupled with reduction in channel and floodplain area due to wing dike and levee construction are the likely explanation for the observed increases in flood stages between 1889 and 1998 channel widths through the study reach decreased 40 and floodplain area for the 100 year flood decreased by 60 in addition manning s n values in the retro model were lower than the values used in the umrsfss suggesting that 1 the modern floodway is rougher than the historic floodway 2 this increased roughness is not a result of explicit changes in land cover but rather 3 the increase is a result of implicit roughness changes such as wing dike construction the retro model developed in this investigation provides a framework for modeling hydrodynamic and ecological responses to altered hydrologic regimes during more than a hundred years of channel modification

thermobarometric constraints on the depth of exposure and conditions of plutonism and metamorphism at deep levels of the sierra nevada batholith tehachapi mountains california we present thermodynamic estimates of pressures temperatures and volatile activities in variably deformed gabbroic to granitic cretaceous 115 100 ma batholithic and framework rocks of the tehachapi mountains southernmost sierra nevada california al contents of hornblende in granitoids imply igneous emplacement at 8 kbar in the southernmost tehachapi mountains with lower pressures 3 7 kbar to the north metamorphic pressures and temperatures for garnet bearing paragneisses and metaigneous rocks were estimated on the basis of garnet hornblende plagioclase quartz and garnet biotite plagioclase quartz thermobarometers disparate results for the metaigneous rocks from the latter system point to the difficulty of applying pelite based thermobarometers to rocks of contrasting composition and mineralogy preferred pressures cluster at 7 1 9 4 and 3 6 4 3 kbar incomplete knowledge of reaction histories however limits our interpretation of the lower pressures because they are minimum estimates the 4 kbar samples are all from a small area and if our interpretation is correct they imply a local more shallow event superimposed on crust once residing at deeper structural levels garnet hornblende and garnet biotite temperatures are less coherent likely owing to retrograde fe mg exchange and range from 570 to 790 c the majority of the rocks are igneous and affected by recrystallization and metamorphism during subsolidus cooling they are not granulites country rock paragneisses are typically migmatized at peak metamorphic conditions near that of the wet granite solidus 690 c veinlike paragenesis of garnet in the metaigneous rocks suggests formation related to the presence of a fluid phase thermodynamic estimates of volatile activities in these garnet bearing assemblages suggest variable mostly co 2 rich fluid compositions in the absence of any pervasive fluid flux the igneous rocks of the tehachapi mountains were thus intruded at depths of 30 km making them the deepest known exposed components of the cretaceous sierra nevada batholith metamorphism occurred at these great depths and perhaps locally after 15 km of uplift before 87 ma implying an uplift rate of 1 2 mm yr a minimum uplift rate is 0 6 mm yr this original uplift and possible subsequent uplift events may have been related to underthrusting of a block of rand schist from what is now the southeast with concomitant widespread ductile deformation the deduced pressure temperature and uplift history is similar to those of high pressure high temperature cretaceous batholithic rocks in salinia and the san gabriel mountains but direct correlation is not wan anted when compared with higher level intrusive rocks from analogous portions of the sierra nevada batholith to the north the tehachapi rocks reveal a deep batholith that is more heterogeneous and somewhat more mafic on average but displaying a similar level of isotopic hybridization involving mantle and crustal sources the batholith is quartz rich at these levels suggestive of a weak ductile middle crust susceptible to prolonged deformation and possible delamination

predicting floodplain inundation raster based modelling versus the finite element approach we compare two approaches to modelling floodplain inundation a raster based approach which uses a relatively simple process representation with channel flows being resolved separately from the floodplain using either a kinematic or diffusive wave approximation and a finite element hydraulic model aiming to solve the full two dimensional shallow water equations a flood event on a short c 4 km reach of the upper river thames in the uk is simulated the models being validated against inundation extent as determined from satellite synthetic aperture radar sar imagery the unconstrained friction parameters are found through a calibration procedure where a measure of fit between predicted and observed shorelines is maximized the raster and finite element models offer similar levels of performance both classifying approximately 84 of the model domain correctly compared with 65 for a simple planar prediction of water surface elevation further discrimination between models is not possible given the errors in the validation data the simple raster based model is shown to have considerable advantages in terms of producing a straightforward calibration process and being robust with respect to channel specification copyright 2001 john wiley sons ltd

fluvial perturbance in the western amazon basin regulation by long term sub andean tectonics haffer s refuge theory proposes that during the arid climatic phases of the late pleistocene tropical lowland forests of amazonia were reduced to isolated patches contributing to the high species richness of the present day forest the theory was developed because no obvious historic or modern geomorphic isolation barriers were recorded in amazonia analyses of radar images combined with stratigraphical data show that in the basinal forelands of the tectonically active andes the geological setting causes long term fluvial perturbance this leads to a temporally structured highly complex mosaic of fossil and present floodplains these dynamics have been present with varying activity and geographic range during the tertiary and quaternary providing site turnover that has not been recognized by the biogeographic tradition of the amazon basin

triassic plutonism in southern california southward younging of arc initiation along a truncated continental margin earliest cordilleran magnatism in the southwestern united states is recorded by a belt of triassic plutons that inme protemzoic basemint of the mojave crustal province and its cratona miogeoclinal cover the belt extends from the western mojave desert through the trausverse ranges to the colorado river trough triassic plutons are predominantly alkali calcic fe and sr mriched quartz mzrdior tes and monzonites the northern part of the belt is comlx sed of two older plutonic mites 241 231 ma which are high k to shoshonitic the southern part of the belt is a younger 218 213 ma sodic alkalic suite the plutonic record in southern california suggests a short lived southward younging continental margin arc sang for eraplacement of triassic plutons sulim on a continental margin modified by s mistral tranqform faulting triassic plutonism in this region was followed by a magmatic lull prior to the onset of voluminous middle to late jurassic cordilleran arc magmatism

water levels in the amazon basin derived from the ers 2 and envisat radar altimetry missions article i nfo this study sets out to analyze the stages of water bodies in the amazon basin derived from the processing of ers 2 and envisat satellite altimetry data for envisat gdr measurements for both ice 1 and ice 2 tracking algorithms were tested for ers 2 the ice 2 data produced by the oscar project was used water level time series over river segments of very different width from several kilometers to less than a hundred of meters were studied the water level time series that can be derived from narrow riverbeds are enhanced by off nadir detections conversely the off nadir effect may degrade the series over large bodies if not properly accounted for comparison at crossovers and with in situ gauges shows that the quality of the series can be highly variable from 12 cm in the best cases and 40 cm in most cases to several meters in the worse cases cautious data selection is clearly a key point to achieve high quality series indeed low quality series mostly result from inclusion of outliers in the data set finally retained for the computation of the series ice 2 and ice 1 tracking algorithms in the envisat data perform almost equally well envisat altimetry is clearly an improvement on ers 2 altimetry

are the circular dark features on comet borrelly s surface albedo variations or pits abstract the highest resolution images of comet 19p borrelly show many dark features which upon casual inspection appear to be low albedo markings but which may also be shadows or other photometric variations caused by a depression in the local topography in order to distinguish between these two possible interpretations we conducted a photometric analysis of three of the most prominent of these features using six of the highest quality images from the september 22 2001 deep space 1 ds1 flyby we find that 1 the radiance in the darkest parts of each feature increases as phase angle decreases similarly to the radiance behavior of the higher albedo surrounding terrain the dark features could be either fully illuminated low albedo spots or alternatively they could be depressions no part of any of the three regions was in full shadow 2 one of the regions has a radiance profile consistent with a rimmed depression the second with a simple depression with no rim and the third with a low albedo spot 3 the regolith particles are backscattering and carbon black is one of the few candidate regolith materials that might explain this low albedo we conclude that borrelly s surface is geologically complex to the limit of resolution of the images with a combination complex topography pits troughs peaks and ridges and some very dark albedo markings perhaps a factor of two to three darker than the average 3 4 albedo of the surrounding terrains our technique utilizing measured radiance profiles through the dark regions is able to discriminate between rimmed depressions rimless depressions and simple albedo changes not associated with topography

large scale hydrologic and hydrodynamic modeling using limited data and a gis based approach summary in this paper we present a large scale hydrologic model with a full one dimensional hydrodynamic module to calculate flow propagation on a complex river network the model uses the full saint venant equations and a simple floodplain storage model and therefore is capable of simulating a wide range of fluvial processes such as flood wave delay and attenuation backwater effects flood inundation and its effects on flood waves we present the model basic equations and gis algorithms to extract model parameters from relatively limited data which is globally available such as the srtm dem gis based algorithms include the estimation of river width and depth using geomorphological relations river cross section bottom level and floodplain geometry extracted from dem etc we also show a case study on one of the major tributaries of the amazon the purus river basin a model validation using discharge and water level data shows that the model is capable of reproducing the main hydrological features of the purus river basin also realistic floodplain inundation maps were derived from the results of the model our main conclusion is that it is possible to employ full hydrodynamic models within large scale hydrological models even using limited data for river geometry and floodplain characterization

spillage sedimentation on large river floodplains active deposition across the floodplains of large rivers arises through a variety of processes collectively these are here termed spillage sedimentation three groups of 11 spillage sedimentation styles are identified and their formative processes described form presences on large river floodplains show different combinations of active spillage styles only some large floodplains have prominent levees some have coarse splays many have accessory channel dispersion and reworking while still water sedimentation in lacustrine environments dominates some lower reaches infills are also commonly funnelled into prior and often linear negative relief forms relating to former migration within the mainstream channel belt 2016 the authors earth surface processes and landforms published by john wiley sons ltd shuttle radar topography mission srtm and landsat 8 data are used to map spillage form types and coverage along a 1700 km reach of the amazon that has an active floodplain width of up to 110 km with a systematic character transformation down valley spillage forms associated directly with mainstream processes rarely account for more than 5 of the floodplain deposits there is a marked decrease in floodplain point bar complexes pbc over 1700 km downstream from 34 to 5 and an increase in the prevalence of large water bodies 2 to 37 and accompanying internal crevasses and deltas 0 to 5 spillage sedimentation is likely within the negative relief associated with these forms depending on mainstream sediment laden floodwater inputs 2016 the authors earth surface processes and landforms published by john wiley sons ltd spillage style dominance depends on the balance between sediment loadings hydrological sequencing and morphological opportunity down river form sequences are likely to follow gradient change prior up river sediment sequestration and the altered nature of spilled loads but also crucially local floodplain relief and incident water levels and velocities at spillage times considering style distribution quantitatively as a spatially distributed set of identifiable forms emphasizes the global variety to spillage phenomena along and between large rivers 2016 the authors earth surface processes and landforms published by john wiley sons ltd

denudation processes and rates in the transverse ranges southern california erosional response of a transitional landscape to external and anthropogenic forcing 1 quantification of denudation in the transverse ranges of california permits reconstruction of spatial and temporal variations in erosion that represent both the response and evolution of interacting hillslopes and channels on the southern front of the san gabriel mountains observational records of the infilling of debris basins and dams define twentieth century landscape erosion rates averaging 1 6 and 0 9 mm yr 1 respectively although all major sediment transport occurs during intense winter storms debris production on hillslopes is greatly enhanced by recurrent fires consequently in this populated region anthropogenic fires have augmented the natural erosion rates we perform a global inversion to estimate the role of precipitation intensity burned areas and local slope on catchment denudation rates after subtracting the effects of anthropogenic fires we estimate landscape denudation rates given natural fire ignition rates increased fire during the past century has augmented sediment production in debris basins by an average of 60 and individual basins show increases up to 400 to identify the dominant hillslope erosion processes the volumetric contribution of landslides was estimated using repeat aerial photographs for the same time interval over which the debris basins have been operative between 1928 and 1973 landsliding produced only 10 of the sediment in debris basins even in the long term when infrequent but volumetrically important landslides occur bedrock landslides appear to contribute a maximum of 50 to the long term landscape denudation previous mapping of soil slippage in the san dimas experimental forest within the san gabriel mountains rice et al 1969 rice and foggin 1971 indicates that shallow landsliding is likely to be the dominant modern hillslope erosion process when compared to incision rates derived from a fluvial shear stress model and to exhumation rates based on low temperature thermochronological data blythe et al 2000 modern natural erosion rates are comparable to denudation rates since the pliocene comparisons of modern erosion rates suggest that debris production on hillslopes and first order channels is directly dependent on vegetation cover and precipitation intensity for higher order channels drainage areas 2 km2 only major storms convey the sediments down valley during the past century some temporal decorrelation occurs between small scale and large scale catchments because hillslope produced sediment is stored in second order and higher channels until major storms mobilize it thus the larger fluvial network damps the episodic fire induced hillslope sediment pulses that occur within small watersheds at a longer temporal scale however uplift and denudation may have been sustained sufficiently long in much of the san gabriel mountains for the topography to reach a macroscale steady state in contrast to rapidly eroding 2 mm yr 1 ranges for which quantification of bedrock landsliding will approximate the sediment flux the san gabriel mountains occupy a niche of intermediate rates 0 1 1 0 mm yr 1 in which a broad suite of hillslope processes including shallow seated and deep seated landslides debris flows and wet and dry ravel contribute to the sediment flux

origin of gneisses in the aureole of the san gabriel anorthosite complex and implications for the proterozoic crustal evolution of southern california granulite facies gneisses along the southwestern margin of the san gabriel anorthosite complex include compositionally banded locally migmatitic felsic gneisses and mafic granulites with rare interlayered augen gneiss and garnet hypersthene spinel aluminous gneiss previous workers accepted a 1 4 ga age for these granulites and a 1 2 ga age for the adjacent anorthosite complex and hence that this proterozoic basement is allochthonous with respect to the southwestern united states part of the north american craton solvus geothermometry in felsic and mafic granulites yields minimum metamorphic temperatures of 900 950 c and new u pb zircon data yield a minimum metamorphic age of 1186 ma coincident with that of the adjacent anorthosite we reinterpret these rocks as a 1190 ma anorthosite complex and its granulite grade thermal aureole geochemical data suggest that the anorthosite complex intruded early proterozoic rocks correlative with the mojave crustal province representing the north american craton exposed to the northeast we conclude that these proterozoic basement rocks represent the southwestern margin of the north american craton and not an exotic terrane accreted in mesozoic or tertiary time

comparison of usgs and dlr topographic models of comet borrelly and photometric applications stereo analysis of images obtained during the 2001 flyby of comet borrelly by nasa s deep space 1 ds1 probe allows us to quantify the shape and photometric behavior of the nucleus the shape is complex with planar facets corresponding to the dark mottled regions of the surface whereas the bright smooth regions are convexly curved the photometric as well as textural differences between these regions can be explained in terms of topography roughness at and below the image resolution without invoking significant variations in single particle properties the material on borrelly s surface could be quite uniform a statistical comparison of the digital elevation models dems produced from the three highest resolution images independently at the usgs and dlr shows that their difference standard deviation is 120 m consistent with a matching error of 0 20 pixel similar to reported matching accuracies for many other stereo datasets the dems also show some systematic differences attributable to manual versus automatic matching disk resolved photometric modeling of the nucleus using the dem shows that bright smooth terrains on borrelly are similar in roughness hapke roughness 20 to c type asteroid mathilde but slightly brighter and more backscattering single scattering albedo w 0 056 henyey greenstein phase parameter g 0 32 the dark mottled terrain is photometrically consistent with the same particles but with roughnesses as large as 60 intrinsically darker material is inconsistent with the phase behavior of these regions many local radiance variations are clearly related to topography and others are consistent with a topographic explanation one need not invoke albedo variations greater than a few tens of percent to explain the appearance of borrelly

recent and ancient fluvial deposition systems in the amazonian foreland basin peru still active sub andean foreland deformation is suggested to have syndepositionally modified the fluvial depositional environments in the peruvian amazonian foreland basin throughout neogene quaternary time modern fluvial aggradation continues to proceed on a large scale c 120 000 km 2 in two differing depositional systems firstly various multistoried floodbasin deposits are derived from the meandering and anastomosing rivers within the subsiding intraforeland basins secondly in the northern part of the pastaza maranon basin the largest known holocene alluvial fan like formation c 60 000 km 2 composed of reworked volcaniclastic debris derived from active ecuadorian volcanoes has been identified the widespread poorly known dissected surface alluvium terra firme which covers the main part of the peruvian amazonian foreland basin shows further evidence of long term foreland deformation and terraces indicate both the effects of tectonism and pleistocene climatic oscillations in northern peru the surface alluvium was deposited by a tertiary fluvial system with palaeocurrents to the west and northwest into the andean foreland basin in southern peru the respective surficial alluvium was part of a post miocene fluvial system flowing northeast into the main amazon basin both systems were gradually abandoned when the eastward migrating andean foreland deformation led to the more distinctive partitioning of the intraforeland basins and the modern drainage system was created

optimal cross sectional spacing in preissmann scheme 1d hydrodynamic models choosing a suitable set of cross sections for the representation of the natural geometry of a river is important for the efficiency of one dimensional 1d hydraulic models but only few guidelines are available for the selection of the most suitable distance between cross sections depending on the hydraulic problem at hand this issue is investigated by examining models of a 55 km reach of the river po italy and a 16 km reach of the river severn united kingdom for both of which high quality laser scanning altimetry are available the high resolution digital terrain models of the two river reaches enabled the construction of a series of hypothetical topographical ground surveys with different spacing between cross sections which could be used as input to a standard 1d model unet both historical and synthetic flood events for the two river reaches were simulated and the results were then analyzed to quantify the accuracy associated with each resolution and to assess how survey resolution impacts the performance of standard 1d models the study results agree with the available suggestions in the literature and provide useful guidelines for 1d hydrodynamic modeling

a subgrid channel model for simulating river hydraulics and floodplain inundation over large and data sparse areas 1 this paper presents a new computationally efficient hydraulic model for simulating the spatially distributed dynamics of water surface elevation wave speed and inundation extent over large data sparse domains the numerical scheme is based on an extension of the hydraulic model lisflood fp to include a subgrid scale representation of channelized flows which allows river channels with any width below that of the grid resolution to be simulated the scheme is shown to be numerically stable and scalable before being applied to an 800 km reach of the river niger in mali the niger application focused on the performance of four different model structures a model without channels two dimensional 2 d model a model without a floodplain one dimensional 1 d model a model of the main channels and floodplain 1 d 2 d model and the subgrid approach developed here inclusion of both the channel network and the floodplain was shown to be essential meaning that large scale models of this region including routing models for land surface schemes will require a floodplain component including subgrid scale channels on the floodplain changed inundation dynamics over the delta significantly and increased simulation accuracy in terms of water level wave propagation speed and inundation extent furthermore only the subgrid model showed a consistent parameterization when calibrated against either gauge or icesat water level data suggesting that connectivity provided by small channels is a strong control on the hydraulics of the floodplain or at the very least that low resolution gridded hydraulic models require additional connectivity to represent the delta flow dynamics

satellite derived digital elevation model dem selection preparation and correction for hydrodynamic modelling in large low gradient and data sparse catchments digital elevation models dems that accurately replicate both landscape form and processes are critical to support modelling of environmental processes topographic accuracy methods of preparation and grid size are all important for hydrodynamic models to efficiently replicate flow processes in remote and data scarce regions high resolution dems are often not available and therefore it is necessary to evaluate lower resolution data such as the shuttle radar topography mission srtm and advanced spaceborne thermal emission and reflection radiometer aster for use within hydrodynamic models this paper does this in three ways i assessing point accuracy and geometric co registration error of the original dems ii quantifying the effects of dem preparation methods vegetation smoothed and hydrologically corrected on hydrodynamic modelling relative accuracy and iii quantifying the effect of the hydrodynamic model grid size 30 2000 m and the associated relative computational costs run time on relative accuracy in model outputs we initially evaluated the accuracy of the original srtm 30 m seamless c band dem srtm dem and second generation products from the aster aster gdem against registered survey marks and altimetry data points from the ice cloud and land elevation satellite icesat srtm dem rmse 3 25 m had higher accuracy than aster gdem rmse 7 43 m based on these results the original version of srtm dem the aster gdem along with vegetation smoothed and hydrologically corrected versions were prepared and used to simulate three flood events along a 200 km stretch of the low gradient thompson river in arid australia using five metrics peak discharge peak height travel time terminal water storage and flood extent the hydrologically corrected dems performed best across these metrics in simulating floods compared with vegetation smoothed dems and original dems the response of model performance to grid size was non linear and while the smaller grid sizes 120 m improved the hydrodynamic model results these offered only slight improvements at very significant computational costs compared to grid size of 120 m with grid sizes 250 m and greater decreasing in model accuracy this study highlights the important impact that the quality of the underlying dem has and in particular how sensitive hydrodynamic models are to preparation methods and how important vegetation smoothing and hydrological correction of the base topographic data for modelling floods in low gradient and multi channel environments

the effects of spatial resolution and dimensionality on modeling regional scale hydraulics in a multichannel river as modeling capabilities at regional and global scales improve questions remain regarding the appropriate process representation required to accurately simulate multichannel river hydraulics this study uses the hydrodynamic model lisflood fp to simulate patterns of water surface elevation wse depth and inundation extent across a 90 km anabranching reach of the tanana river alaska to provide boundary conditions we collected field observations of bathymetry and wse during a 2 week field campaign in summer 2013 for the first time at this scale we test a simple raster based model s capabilities to simulate 2 d in channel patterns of wse and inundation extent additionally we compare finer resolution 25 m 2 d models to four other models of lower dimensionality and coarser resolution 100 500 m to determine the effects of simplifying process representation results indicate that simple raster based models can accurately simulate 2 d in channel hydraulics in the tanana also the fine resolution 2 d models produce lower errors in spatiotemporal outputs of wse and inundation extent compared to coarse resolution 1 d models 22 6 cm versus 56 4 cm rmse for wse and 90 versus 41 critical success index values for simulating inundation extent incorporating the anabranching channel network using subgrid representations for smaller channels is important for simulating accurate hydraulics and lowers rmse in spatially distributed wse by at least 16 as a result better representation of the converging and diverging multichannel network by using subgrid solvers or downscaling techniques in multichannel rivers is needed to improve errors in regional to global scale models

mapping large scale river flow hydraulics in the amazon basin 1 research on actual requirements for a numerically consistent representation of flow dynamics in large scale river flood models are needed to improve both modeling performance and computational efficiency still regional and global scale characterizations of river hydrodynamics are absent a first attempt to map river hydrodynamics in the amazon basin is presented flood wave type maps at 0 25 spatial resolution are derived from a classification method based on the analysis of saint venant equation terms global river geometry data sets derived from both digital elevation models and empirical equations supported by stream gauge observations are used as input variables errors of input variables are estimated and a sensitivity analysis is performed results show that 64 5 of rivers headwaters and high slope rivers can be represented by the kinematic wave ki 34 5 main amazon tributaries low slope and wetland regions by the diffusive wave df and 1 lower amazon by the full saint venant equations sv in a rigorous scenario i e a case where the most restricted classification of each grid cell is considered 33 is classified as ki 62 as df and 5 as sv most of the basin presents subcritical flow with very low froude number fr while the andean region is dominated by larger fr values and supercritical flow can be found according to our evaluation mostly based on in situ data the map has a percentage of detection of 83 4

amazon flood wave hydraulics summary a bathymetric survey of 575 km of the central amazon river and one of its tributaries the purus are combined with gauged data to characterise the amazon flood wave and for hydraulic modelling of the main channel for the period june 1995 march 1997 with the lisflood fp and hec ras hydraulic models our investigations show that the amazon flood wave is subcritical and diffusive in character and due to shallow bed slopes backwater conditions control significant reach lengths and are present for low and high water states comparison of the different models shows that it is necessary to include at least the diffusion term in any model and the rmse error in predicted water elevation at all cross sections introduced by ignoring the acceleration and advection terms is of the order of 0 02 0 03 m the use of a wide rectangular channel approximation introduces an error of 0 10 0 15 m on the predicted water levels reducing the bathymetry to a simple bed slope and with mean cross section only introduces an error in the order of 0 5 m these results show that when compared to the mean annual amplitude of the amazon flood wave of 11 12 m water levels are relatively insensitive to the bathymetry of the channel model the implication for remote sensing studies of the central amazon channel such as those proposed with the surface water and ocean topography mission swot is that even relatively crude assumptions regarding the channel bathymetry will be valid in order to derive discharge from water surface slope of the main channel as long as the mean channel area is approximately correct

characteristics and causal factors of hysteresis in the hydrodynamics of a large floodplain system poyang lake china abstract a previous modeling study of the lake floodplain system of poyang lake china revealed complex hysteretic relationships between stage storage volume and surface area however only hypothetical causal factors were presented and the reasons for the occurrence of both clockwise and counterclockwise hysteretic functions were unclear the current study aims to address this by exploring further poyang lake s hysteretic behavior including consideration of stage flow relationships remotely sensed imagery is used to validate the water surface areas produced by hydrodynamic modeling stage area relationships obtained using the two methods are in strong agreement the new results reveal a three phase hydrological regime in stage flow relationships which assists in developing improved physical interpretation of hysteretic stage area relationships for the lake floodplain system for stage area relationships clockwise hysteresis is the result of classic floodplain hysteretic processes e g restricted drainage of the floodplain during recession whereas counterclockwise hysteresis derives from the river hysteresis effect i e caused by backwater effects the river hysteresis effect is enhanced by the time lag between the peaks of catchment inflow and yangtze discharge i e the so called yangtze river blocking effect the time lag also leads to clockwise hysteresis in the relationship between yangtze river discharge and lake stage thus factors leading to hysteresis in other rivers lakes and floodplains act in combination within poyang lake to create spatial variability in hydrological hysteresis these effects dominate at different times in different parts of the lake and during different phases of the lake s water level fluctuations creating the unique hysteretic hydrological behavior of poyang lake

accuracy and resolution of shuttle radar topography mission data 1 we assess the accuracy and resolution of topography data provided by the shuttle radar topography mission srtm through spectral comparisons with the national elevation dataset ned and a high resolution laser data set of the 1999 hector mine earthquake rupture we find that srtm and the ned are coherent for wavelengths greater than 200 m however the spatial resolution of the ned data is superior to the srtm data for wavelengths shorter than 350 m likely due to the application of a boxcar filter applied during final srtm processing stages from these results a low pass filter decimation algorithm can be designed in order to expedite large area srtm applications