Gullies are significant contributors of sediment to streams in the southeastern USA. This study investigated gully erosion in the clay-rich soils of east Tennessee under a humid subtropical climate. The aims of this study were to (1) estimate long-term erosion rates for different gully geomorphic settings, (2) compare patterns of erosion for the different settings, and (3) model the response of gully erosion to freeze-thaw events. Erosion was measured weekly from June 2012 to August 2018 using 105 erosion pins distributed in gully channels, interfluves, and sidewalls. Erosion rates were estimated from average slopes of lines of best fit of pin lengths versus time. Maximum and minimum temperature was calculated daily using an on-site weather station and freeze-thaw events were identified. Gully erosion was modeled using antecedent freeze-thaw activity for the three geomorphic settings. Long-term erosion rates in channels, interfluves, and sidewalls were 2.5 mm/year, 20 mm/year, and 21 mm/year, respectively; however, week-by-week erosion was statistically different between the three settings, indicating different erosive drivers. Models of erosion with lagged freeze-thaw variables explained up to 34.8% of the variability in erosion variables; sidewall erosion was most highly related to freeze-thaw activity. Freeze-thaw in prior weeks was an important variable in all erosion models.

Made available in DSpace on 2017-07-21T18:15:27Z (GMT). No. of bitstreams: 1 WolliverDias.pdf: 3685063 bytes, checksum: 2953027d085ff6193c938c6c73f7b42d (MD5) Previous issue date: 2012-04-26 / Fundação Araucária de Apoio ao Desenvolvimento Científico e Tecnológico do Paraná / The banks erosion in river is in the most dynamic processes of the landscape and can be influenced by several factors. The bank erosion is a result of the interaction between the ravines conditions and the fluvial characteristics. Therefore, erosion rates are determined by the ravines resistance against the potential erosive flow. The adjacent land use is also a determining factor in erosion processes, once the protection exerted by riparian vegetation ceases to exist when it is replaced for other ends. This study aimed to analyze the dynamics of banks erosion along the Guabiroba River located in Guarapuava - PR. However, it was considered the physical parameters of the evaluated sections: material texture, ravines face resistance, slope, and the fluvial stream characteristics. The estimated margins erosion was performed by monitoring erosion pins (volumetric technique). Thus, it was possible to quantify rates of river banks erosion at Guabiroba River, as well as identify and classify the occurring erosion processes. The material loss value along the river banks at Guabiroba River was approximately 1684.7 tons, registered between October 2010 and January 2012, mainly represented by the interaction of corrosion processes and undermining. / A erosão das margens de rios encontra-se entre os processos mais dinâmicos da paisagem, podendo ser influenciado por diversos fatores. A erosão das margens é resultado da interação entre as condições dos barrancos e das características fluviais. Assim, as taxas de erosão são determinadas pela resistência do barranco frente ao potencial erosivo do fluxo. O uso da terra nas adjacências também é determinante nos processos erosivos, tendo em vista a proteção exercida pela vegetação ripária que deixa de existir quando as matas ciliares são substituídas por outros usos. O presente trabalho buscou analisar a dinâmica da erosão de margens plenas ao longo do rio Guabiroba, localizado no município de Guarapuava - PR. Para tanto, levou-se em consideração os parâmetros físicos das seções avaliadas: textura do material, resistência da face do barranco, declividade e características do canal fluvial. A estimativa da erosão das margens foi realizada através do monitoramento dos pinos de erosão (técnica volumétrica). Desta forma, foi possível quantificar as taxas de erosão das margens do rio Guabiroba, bem como identificar e classificar os processos erosivos ocorrentes. O valor de perda de material ao longo das margens do rio Guabiroba foi de aproximadamente 1684,7 toneladas, registrados entre outubro de 2010 e janeiro de 2012, representados principalmente pela interação dos processos de corrasão e solapamento.