A Metrópole é um fenômeno em movimento. Seu processo, a metropolização, se constitui a partir de várias relações que envolvem a Natureza e a História. Esta pesquisa investiga a particularidade da apropriação do ambiente fluvial das várzeas da Bacia do Pirajuçara no processo de formação da metrópole de São Paulo. Historicamente, continuidades e descontinuidades se sucederam neste processo sob uma contradição fundamental: a afirmação da várzea como ambiente fluvial e a produção do espaço como sua negação. As intervenções nos rios e nas várzeas objetivam a metrópole sob as determinações formais do capital em geral. Tal condição cristaliza um papel muito particular deste ambiente na divisão do trabalho, fundamentalmente como espaços de circulação. Neste contexto, a relação entre a apropriação do ambiente fluvial das várzeas e a produção do espaço na metrópole se constitui numa problemática em que a catástrofe das inundações se põe como limite ao processo. A nova prática de retenção do escoamento nos reservatórios de contenção de cheias (piscinões) se objetiva nas ideologias do ambientalismo e da sustentabilidade. O que aparece como ruptura se apresenta como continuidade da apropriação das várzeas para a realização da metrópole como espaço de reprodução do valor. / The Metropolis is a phenomenon in movement. Its process, the metropolization consists of many relations involving nature and history. This research investigates the peculiar fluvial environment appropriation of the floodplains of the Pirajuçara River Basin during the formation of the metropolis of São Paulo. Historically, continuities and discontinuities have been succeeding each other in this process in a fundamental contradiction: the assertion of the floodplain as a river environment and the production of space as its negation. Interventions in rivers and wetlands in the city aim the metropolis under the formal determinations of capital in general. Such condition crystallizes a very particular role of this environment in labor division mainly as passage space. In this context, the relationship between the appropriation of the environment of river floodplains and the production of space in the metropolis composes a set of problems in which the disaster of flooding arises as the limit process. The new practice of restraining the flow with flood control reservoirs (piscinões) has its objectives in environmentalism and sustainability ideologies. What appears as disruption shows up as continuity of floodplains appropriation in order to carry out the metropolis as an area for value reproduction.

This thesis presents an experimental study, both in the field and laboratory to cast more light on the primary role of the river floodplains in releasing and/or removing total-P to/from the in-stream load, under high runoff and flood conditions, by investigating the soil total-P spatial and vertical deposition patterns and topsoil erodibility, along the three (3) main river sections (e.g., headwaters, transfer and deposition zones) of an agricultural watershed, such as the Turkey River (TR). In soils, phosphorus, P, primarily exists as sediment-bound and less often as dissolved. During wet hydrological years, soil erosion and surface runoff are the main P release and transport mechanisms, while during dry hydrological years, P leaches to the deeper soil levels and is transported to freshwaters through groundwater discharge. In between the upland areas and the river network, there is a buffer zone, known as floodplain that regulates the flux exchanges between these two watershed components. Floodplains play an essential role in the riverine system health by supporting important physical and biochemical processes and improving the water quality downstream. These characteristics have led to the conclusion that floodplains primarily act as sinks for P. However, floodplains are subject to erosion as well, where soil particles along with the attached P are removed from the topsoil or enter re-suspension, under high runoff and flood conditions. The study provides an insight into the soil total-P deposition patterns across the floodplains of five (5) identified field sites and couples them with topsoil erodibility to eventually address the research objectives, which can be summarized as follows: (i) investigation of the soil total-P spatial and vertical variability across the floodplains along the main river zones and development of relationships between P variability and soil physical properties (e.g., soil texture); (ii) identification and characterization of the soil total-P deposition patterns across the floodplains (e.g., short- vs. long-term P deposition areas); and (iii) comparisons of the soil total-P concentrations and critical shear stresses among the main river zones and determination of their primary function either as P sources or sinks, under high runoff and flood conditions. Following that line of thinking, this research results comprise of three (3) parts, each one addressing a specific objective. The first part of the results includes the soil texture and total-P concentration analyses of the extracted soil profiles to identify the soil total-P spatial and vertical deposition patterns across the floodplains, as well as, to investigate the total-P variability with respect to soil physical properties (e.g., soil texture). The second part of the results focuses on investigating the role of topography (e.g., flat vs. ridge vs. swale land surfaces) and flood characteristics (e.g., frequency, magnitude, duration) in soil total-P spatial and vertical deposition patterns across the river floodplains to understand the time-scale nature of the P storage. The last part of the results presents the experimentally determined topsoil critical shear stress values and erodibility rates to characterize the floodplains’ primary function, based on their location along the three (3) main river zones, either as sources or sinks for total-P, during high runoff and flood conditions. Overall, the results of this research show that (i) the total-P concentration in soils is tightly related to the fine particle content and monotonic linear relationships can be established between the two variables. In other words, the higher the fine particle content, the higher the total-P concentration in soils; (ii) a mixture of two normal distributions fit the log-transformed soil total-P concentration data of each field site considered in this study. The fitted distributions successfully capture the two peaks of the soil total-P concentration data correspond to the lower and upper floodplain terraces; (iii) the lower floodplain terraces (e.g., 2- and 5-year floodplains) are characterized by significantly lower soil fine particle percentage contributions and total-P concentrations compared to the upper floodplain terraces, at a 5% confidence level. These patterns can be attributed to the fact that the lower floodplain terraces are frequently flooded and/or under inundation compared to the upper floodplain terraces and thus part of the fine particles along with the attached P are regularly winnowed away. Therefore, the lower floodplain terraces can be considered as short-term P storage means, in between two consecutive major flood events, while the upper floodplain terraces act more as long-term P storage means; (iv) there is a longitudinal increase in the topsoil critical shear stress values, which follows the increase in the fine particle content reconfirming the principle that the more the fine particle content in soils, along with the existence of vegetation with dense, well-developed root systems, the more resistant to erosion are the soils. From a soil erodibility perspective, the floodplains along the headwaters zone can be considered as major fine sediment and total-P sources contributing to the in-stream loads, while the floodplains along the deposition zone primarily act as sinks for fine sediment and total-P. As far as the role of the floodplains along the transfer zone, they can be considered as sinks for fine sediment and total-P during low magnitude runoff and flood events (e.g., 2-; 5-; and 10-year return periods), while during higher magnitude events, they act as sources releasing fine sediment and total-P; and (v) topsoil samples characterized by dense, well-developed root systems fall approximately along a trend line that follows almost a parallel pattern with the trend line for the topsoil samples without dense and/or well-developed root systems. The existence of dense, well-developed vegetation root systems to topsoil consistently increases its critical shear stress threshold (e.g., > 1 Pa) and thus its ability to resist erosion.

River systems, such as the Columbia River in the Pacific Northwest, USA have been influenced by human activities, resulting in changes to the physical processes that drive landform evolution. This work describes an inventory of landforms along the Columbia River estuary between the Pacific Ocean and Bonneville Dam in Oregon and Washington. Groupings of landforms are assigned to formative process regimes that are used to assess historical changes to floodplain features. The estuary was historically a complex system of channels with a floodplain dominated by extensive tidal wetlands in the lower reaches and backswamp lakes and wetlands in upper reaches. Natural levees flank most channels in the upper reaches, locally including areas of ridge and swale topography and crevasse splays that intrude into backswamps. Other Holocene process regimes affecting floodplain morphology have included volcanogenic deltas, tributary fans, dunes, and landslides. Pre-Holocene landforms are locally prominent and include ancient fluvial deposits and bedrock. Historical changes to streamflow regimes, floodplain isolation by flood-control systems, and direct anthropogenic disturbance have resulted in channel narrowing and limited the amount of floodplain that can be shaped by flowing water. Floodplain isolation has caused relative subsidence of tidal floodplains along much of the lower estuary. Most extant landforms are on trajectories controlled by humans and new landforms are mostly created by humans.

In river ecology the description and understanding of near-natural ecosystem functionality is a difficult task to achieve as the majority of river floodplains have been intensively impacted by human activities. This work addresses ecological functionality of a relatively unimpacted large river system, focussing on the lateral dynamic and connectivity mechanisms driving aquatic vegetation processes. Macrophytes were found to be very patchily distributed at the riverscape scale, being mainly confined to low energy lateral habitats in the floodplain, such as backwaters. Backwaters provided favourable conditions for plants to colonise and recruit and contributed highly to species diversity and productivity at the floodplain scale. Differences between backwaters were attributed to the frequency of connectivity with the main channel during flood events. Nevertheless, the ecological mechanism driving diversity through flooding appears not to be related to flow disturbance. Biomass produced in backwaters was found to remain stable after potentially scouring floods. Therefore the hypothesis that flood disturbances promote species diversity through the removal and destruction of biomass and rejuvenate communities such that species coexistence is increased was rejected. Rather, it appears that diversity in backwaters increases along a temporal gradient as a response to the input of colonists and their accumulation overtime through successive flood inputs. Despite the apparently non-destructive effect of floods on macrophyte biomass, backwaters appear to have a significant role in exporting large amounts of plant propagules from the site of production. Backwaters represented a net source of propagules which highly enriched the main channel pool of potential colonists. However, whereas propagules could be dispersed for long distances in flood flows the probability for them to reach a suitable downstream habitat was extremely low. This work showed that dispersal at baseflow and entry to backwaters through the downstream end after short dispersal drift provided a greater chance of successful colonisation despite the individually much shorter distance moved. Backwaters were demonstrated to be rather isolated aquatic habitats, even though they experience hydrological connectivity, suggesting that primary colonisation of these sites is a limiting step. Instead, colonisation was shown to rely primarily on propagules generated internally by established plants. Whereas colonisation could occur via internal re-organisation of existing plant propagules, the backwater seed bank could also contribute to the macrophytes species established in backwaters. Such contribution was consistently low to medium along a gradient of disturbances and connectivity and showed independence from such river flow processes. Species richness was found to be higher in the established species than in the seed bank, suggesting that asexual reproduction is prioritised by aquatic vegetation in riverine backwaters. The occurrence or persistence of macrophyte species in backwaters depends upon rhizome and plant shoot regeneration. The lack of influence of connectivity revealed that plants may originate from both in situ and externally waterborne vegetative propagules derived from other upstream backwaters. This research demonstrated that the lateral dynamic and associated connectivity are major components of river floodplain ecology which generate a wide spectrum of habitats and have a controlling effect on vegetation processes. Therefore a naturally dynamic ecological state is required to support ecosystem functionality in large river floodplains and especially to maintain a high level of species diversity, productivity and colonisation of backwaters by macrophytes.

This thesis presents a discussion on the study undertaken in the application of the monthly time step Pitman rainfall-runoff model to the Kafue River basin. The study constituted one of the initial steps in the capacity building and expansion of the application of hydrologic models in the southern African region for water resources assessment, one of the core areas of the Southern African FRIEND project (Flow Regimes from International Experimental Network Data). The research process was undertaken in four major stages, each stage working towards achieving the research objectives. The first stage was the preparation of spatial data which included the selection and delineation of sub-catchments and inclusion of spatial features required to run the Pitman model and transferring the spatial data into SPATSIM. The second stage was the preparation of input data, mainly rainfall, streamflow, evaporation, and water abstraction data. This information was then imported into SPATSIM, which was able to assist in the further preparation of data by assessment of the input data quality, linking of observed flows and spatial interpolation of point rainfall data to average catchment rainfall in readiness for running and calibration of the model. The third stage was the running and calibration of the Pitman model. Use was made of both the automatic calibration facility, as well as manual calibration by means of the time series graph display and analysis facility of SPATSIM. Model calibration was used to obtain the best fit and an acceptable correlation between the simulated and the observed flows and to obtain simulation parameter sets for sub-catchments and regions within the Kafue catchment. The fourth stage was the analysis and evaluation of the model results. This included verification of results over different time periods and validation and testing of parameter transfers to other catchments. This stage also included the evaluation of SPATSIM as a tool for applying the model and as a database for the processing and storage of water resources data. The study’s output includes: A comprehensive database of hydrometeorological, physical catchment characteristics, landuse and water abstraction information for the Kafue basin; calibrated Pitman model parameters for the sub-catchments within the Kafue basin; recommendations for future work and data collection programmes for the application of the model. The study has also built capacity by facilitating training and exposure to rainfall-runoff models (specifically the Pitman model) and associated software, SPATSIM. In addition, the dissemination of the results of this study will serve as an effective way of raising awareness on the application of the Pitman model and the use of the SPATSIM software within Zambia and the region. The overall Pitman model results were found to be satisfactory and the calibrated model is able to reproduce the observed spatial and temporal variations in streamflow characteristics in the Kafue River basin.

Planícies de inundação são áreas sujeitas a fluxo episódico de água, que devido a disponibilidade de água, nutrientes e substrato estável, foram largamente afetadas desde o surgimento e subsequente evolução de plantas vasculares terrestres. Neste contexto, a escassez de exemplos documentados de planícies de inundação formadas anteriormente ao período Siluriano contrasta com décadas de debate acerca dos efeitos da evolução de plantas terrestres em estilos de canais fluviais. Dada a importância de planícies de inundação como sítios de acumulação de partículas sedimentares, intemperismo de minerais silicáticos e desenvolvimento de perfis de solo, esta falta de dados sobre planícies de inundação antigas tem importante impacto na forma como entendemos sistemas transporte de sedimento, o registro climático e ciclos geoquímicos globais do Precambriano e início do Paleozoico. Com o objetivo de aprimorar os modelos existentes de planícies de inundação pré-vegetação, desenvolvidos antes da evolução de plantas vasculares no continente, três exemplos de ambientes aluviais foram investigados com o emprego de análise de fácies e de elementos arquiteturais. Os exemplos escolhidos oferecem a oportunidade de avaliar não apenas a existência destes depósitos sedimentares, mas também de propor um modelo para a deposição deste ambiente sedimentar particular. A Formação Tombador (Supergrupo Espinhaço, BA) é parte de espessa sucessão sedimentar de idade Mesoproterozoica, que inclui depósitos aluviais e costeiros; O Grupo Santa Bárbara e o Grupo Guaritas (Supergrupo Camaquã, RS), que se estendem do fim do Neoproterozoico ao início do Cambriano, representam sucessões aluvias depositadas em rift continental. O estudo destes três exemplos permitiu a determinação de possíveis feições comuns a planícies de inundação pré-vegetação, como depósitos de granulação relativamente mais grossa em comparação a exemplos modernos, melhor preservação de estruturas sedimentares e abundância de facies arenosas representativas de condições de fluxo e sedimentação desconfinadas. Os exemplos de planícies de inundação pré-vegetação utilizadas para compor este modelo simplificado compartilham de semelhanças marcantes a depósitos de rios efêmeros, que são frequentemente citados como explicação para a formação de espessos depósitos de arenitos-em-lençól. A reavaliação de depósitos fluviais pré-vegetação, considerando a possibilidade de que planícies de inundação de granulação grossa, sugere que este ambiente deposicional tem sido bastante negligenciado, e que inferências climáticas obtidas da alternância de estilos fluviais contrastantes pode ser equivocada, uma vez que a alternância de registro de rios perenes e efêmeros podem ser parte de um mesmo sistema deposicional. / Floodplains are areas of unconfined and episodic water flow that, given the generalized availability of water, nutrients and stable substrate, have been extensively affected by the first appearance and subsequent evolution of land plants. In this respect, the scarcity of documented examples of pre-Silurian floodplain deposits contrasts with the continuous and decades-long debate on the effects of land plants evolution on fluvial channel styles. Given the importance of floodplains as sites of sediment storage, silicate minerals weathering and development of soil profiles, this lack of data on ancient floodplains has great implications for our understanding of the source-to-sink systems, the climate record and the global geochemical cycles of the Precambrian and the Early Paleozoic. Aiming at the improvement of the current models regarding pre-vegetation floodplains, which were developed prior to the evolution of vascular land plants, three examples of alluvial environments were investigated trough facies and architectural elements analysis. The used examples offer the opportunity to assess not only the existence of such deposits, but also to propose a model for the deposition of those particular sedimentary environments. The Mesoproterozoic Tombador Formation (Espinhaço Supergroup, Northeastern Brazil) is part of thick sedimentary deposits, which includes alluvial and coastal environments; the Neoproterozoic Santa Bárbara Group and the Cambrian Guaritas Group (Camaquã Basin, Southern Brazil) represents alluvial successions deposited in a continental rift system. The study of the three examples allowed the determination of some common features to pre-vegetation floodplain deposits, like relatively coarser grained deposits in comparison to modern examples, better preservation of sedimentary structures and abundance of sandstone facies representative of sedimentation in unconfined flow settings. The pre-vegetation floodplain deposits used to draw this simplified model share characteristics remarkably similar to ephemeral river deposits, which are frequently evoked to explain the formation of thick successions of sheet-like sandstone deposits. The re-evaluation of pre-vegetation fluvial deposits considering the possibility of coarse grained floodplains suggests that this environment have been greatly overlooked, and that climate inferred from the alternation of contrasting fluvial styles might be misleading, since alternation of deposits representing perennial and ephemeral fluvial deposits can be part of the same depositional system.

A Metrópole é um fenômeno em movimento. Seu processo, a metropolização, se constitui a partir de várias relações que envolvem a Natureza e a História. Esta pesquisa investiga a particularidade da apropriação do ambiente fluvial das várzeas da Bacia do Pirajuçara no processo de formação da metrópole de São Paulo. Historicamente, continuidades e descontinuidades se sucederam neste processo sob uma contradição fundamental: a afirmação da várzea como ambiente fluvial e a produção do espaço como sua negação. As intervenções nos rios e nas várzeas objetivam a metrópole sob as determinações formais do capital em geral. Tal condição cristaliza um papel muito particular deste ambiente na divisão do trabalho, fundamentalmente como espaços de circulação. Neste contexto, a relação entre a apropriação do ambiente fluvial das várzeas e a produção do espaço na metrópole se constitui numa problemática em que a catástrofe das inundações se põe como limite ao processo. A nova prática de retenção do escoamento nos reservatórios de contenção de cheias (piscinões) se objetiva nas ideologias do ambientalismo e da sustentabilidade. O que aparece como ruptura se apresenta como continuidade da apropriação das várzeas para a realização da metrópole como espaço de reprodução do valor. / The Metropolis is a phenomenon in movement. Its process, the metropolization consists of many relations involving nature and history. This research investigates the peculiar fluvial environment appropriation of the floodplains of the Pirajuçara River Basin during the formation of the metropolis of São Paulo. Historically, continuities and discontinuities have been succeeding each other in this process in a fundamental contradiction: the assertion of the floodplain as a river environment and the production of space as its negation. Interventions in rivers and wetlands in the city aim the metropolis under the formal determinations of capital in general. Such condition crystallizes a very particular role of this environment in labor division mainly as passage space. In this context, the relationship between the appropriation of the environment of river floodplains and the production of space in the metropolis composes a set of problems in which the disaster of flooding arises as the limit process. The new practice of restraining the flow with flood control reservoirs (piscinões) has its objectives in environmentalism and sustainability ideologies. What appears as disruption shows up as continuity of floodplains appropriation in order to carry out the metropolis as an area for value reproduction.

Submitted by Renata Lopes (renatasil82@gmail.com) on 2017-03-30T12:41:23Z No. of bitstreams: 1 eliesecristinadeoliveira.pdf: 658851 bytes, checksum: 68287f985bb39c1fe440518b3cd33589 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-04-03T18:49:19Z (GMT) No. of bitstreams: 1 eliesecristinadeoliveira.pdf: 658851 bytes, checksum: 68287f985bb39c1fe440518b3cd33589 (MD5) / Made available in DSpace on 2017-04-03T18:49:19Z (GMT). No. of bitstreams: 1 eliesecristinadeoliveira.pdf: 658851 bytes, checksum: 68287f985bb39c1fe440518b3cd33589 (MD5) Previous issue date: 2008-06-18 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / O entendimento da dinâmica biogeoquímica é um ponto central na tentativa de, racionalmente, manejar recursos e minimizar os impactos gerados por atividades antrópicas nos sistemas aquáticos amazônicos, especialmente devido à importância dessa região no ciclo global do carbono. O presente estudo pretende contribuir com esta temática avaliando a composição isotópica e química da água na várzea de Curuai (PA). As amostras de água foram coletadas na superfície da coluna d’água no Lago Grande em três períodos distintos do ciclo hidrológico. Os valores de concentrações e de δ13C (-28,4 a -23,3‰) e δ15N (2,0 a 5,0‰) para os sólidos fino em suspensão (SFS) revelaram mudanças consideráveis na quantidade e na composição da matéria orgânica ao longo do ciclo hidrológico. Enquanto no período de enchente a planície recebe materiais das áreas laterais e rio Amazonas, nos períodos de cheia e vazante as contribuições autóctones podem ser registradas com maior intensidade no sinal isotópico do SFS. A composição isotópica do carbono inorgânico dissolvido (CID) também parece refletir a ciclagem da matéria orgânica na várzea. A composição química da água, por sua vez, é muito similar à do rio principal e está mais intensamente relacionada ao pulso de inundação e à litologia na bacia hidrográfica. Foi observada uma maior influência da drenagem local no período de vazante, especialmente sobre as concentrações de Cl- e HCO-3. Este estudo evidencia o controle do pulso de inundação e da hidrodinâmica interna sobre a química e a composição da matéria orgânica nos sistemas de várzeas da bacia Amazônica. / The understanding of the biogeochemical dynamics is a central point for the implementation of sustainable resources management and to minimize the impacts of human activity over the Amazonian aquatic systems. It becomes more critic when we consider the role of Amazon region plays in the global carbon cycle. The present study tries to contribute to this approach by examining the seasonal variation in isotopic and chemical composition of the water in Lago Grande de Curuai floodplain, Brazil, a complex system of lakes linked to the Amazon River by several channels. Water samples were taken from surface of the Lago Grande in three different phases of the hydrological cycle. The δ13C (from -28,4 to -23,3‰) and δ15N (from 2,0 to 5,0‰) values and concentrations of the fine suspended sediments (FSS) revealed considerable variability in the lake organic matter abundance and composition. These patterns are a result of system internal functioning along the hydrological cycle. If on the one hand water and material inputs from the catchment area and Amazon river do influence the isotopic signal of the FSS the during rising water, on the other hand an effect of the primary production seems to be recovered in the FSS during periods of high water and falling. Additionally, the DIC isotopic composition seems to reflect the seasonality in organic matter inputs to the “varzea”. The water chemical composition is quite similar to that of the main river and was probably more related to the flood pulse and drainage basin lithology. A greater influence of the local drainage was observed during the falling water period, especially over the Cl- and HCO-3 concentrations. This work brings evidences that the flood pulse and the internal dynamics of the floodplains in the Amazon basin are ultimately decisive to its biogeochemistry.

A Dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the Degree of Master of Science in Geology. Johannesburg 2013 / The Nyl River floodplain, located in the Limpopo Province, is one of the few active sedimentary basins that exist within the South African interior, providing a unique opportunity to study the effect of climate change on fluvial systems. Progradation of tributary fans into the Nyl/Mogalakwena River has raised the surface by 30 m and forced the course of the river westwards towards the Waterberg. Periods of progradation deposited thick sequences of coarse-grained sediments with sand- to gravel-sized mean grain sizes and coarsely-skewed populations in the distal reaches of the tributary fans. These periods were interspersed with periods of relative non-deposition, when active sedimentation on the fan ceased and shallow lakes (or vleis) developed in the trunk river, resulting in deposition of fine-grained, organic-rich, floodplain sediment layers with silt-sized mean grain sizes and finely-skewed distributions in the extreme outer reaches of the tributary fan. The alternating progradational sequences and non-deposition events produced interlayered floodplain and fan deposits in the furthest reaches of the tributary fans along the banks of the Nyl/Mogalakwena River. Incised river cuts within the Rooisloot tributary fan were dated using OSL and 14C techniques. For OSL samples, the SAR protocol was used to measure the equivalent dose and the burial dose was determined using the CAM and MAM. Emission counting methods, including TSAC, GM-beta counting and HRGS were used to determine the dose-rate. The OSL ages ranged from 99 years to 3884 years, constraining the sampled deposits within the late Holocene. Although the 14C ages agreed with this range, carbon contamination of the samples resulted in inverted and overestimated ages. Based on stratigraphic relationships the non-deposition events have been dated at approximately 750–800 years ago, 600 years ago, 475 years BP and 100–150 years ago and two major periods of aggradation at ~ 800–1000 years ago and ~ 500–700 years ago. The rate of aggradation (0.29 cm/year) calculated implies that the entire 30 m deposit could have been deposited in 9 000 years. However, an independent study by McCarthy et al. (2011) proved that tributary sedimentation began prior to 220 ka. Therefore, in order to deposit 30 m of sediment over 220 ka, either the mid – late Quaternary sedimentation rate was lower than the recent past (Late Holocene) or the system periodically undergoes extensive erosion in order to flush the accumulated sediment from the tributary fan system.

Utilizing survey data gathered from local local level floodplain administrators (FPAs) operating within Federal Emergency Management Agency Region 6, this study provides a more nuanced understanding of perceived competency among FPAs across key floodplain management topics through the use of a principal component analysis (PCA). PCA identified six distinct components related to perceived competency among FPAs including; Modification and Update Process, General Knowledge, Grants and Programs, Analysis, Development and Real Estate, and Administration and Outreach. The study then employed regression analyses to identify organizational and individual level characteristics that predict perceived competency. Data analyses identified several organizational variables as significant positive predictors of perceived competency including working within an urban community, full-time job status and overall workload percentage dedicated to floodplain management. Additionally, several individual characteristics such as educational attainment, professional certification, previous disaster experience, and years of experience working as an FPA were also identified as significant positive predictors of perceived competency. Based on these findings the study makes several recommendations about improvements to training and educational materials for practitioners and students.