In the southern Appalachians, the dominant soil order, Ultisols, is highly susceptible to erosion. If left unmanaged these soils can develop into gully systems resulting in land degradation. This study examines gully development through sidewall mass-wasting events at a high temporal resolution using 30 minute time-lapse photography. Prior research at this site found significant mass wasting events occurring between weekly monitoring periods. By shortening the interval of observation to 30-minutes, a more accurate understanding of the frequency and intensity of these mass-wasting events, and their relation to meteorological factors, can be determined. Photographs of a gully (approximately 1.5 m deep by 3 m wide at the top) were captured every 30 minutes from 11/29/17 - 2/18/2018 with a WingScape outdoor time-lapse camera mounted on a plastic stake 3.16 m from the gully facing northwest and upstream into the gully channel. A total of n=1648 images were coded using presence/absence indices for six observed geomorphic processes: creep on NE facing sidewall, creep on SW facing sidewall, slump on NE facing sidewall, slump on SW facing sidewall, channel aggradation, and channel development. Precipitation and temperature data were collected every 5 minutes using a Davis Vantage Pro 2 weather station located 240 m from the gully, and were aggregated to various time intervals. Precipitation received in previous 0.5, 1, 1.5, 2, 3, 6, 12, 24, 36, 48, and 72 hours were calculated for each image. Two binary temperature variables were generated with values of “1” if temperature dropped below 0 °C (32 °F) during the prior 30 minutes or 24 hours, respectively, and “0” otherwise. Logistic regression models (forward conditional method) for the six geomorphic index variables were generated using the precipitation and temperature data. For creep on the NE facing sidewall, the significant independent variables are 3 hour and 72 hour prior rain, and freeze conditions in the previous 0.5 and 24 hours. On the SW facing sidewall, rain and temperature variables were also important for creep; rain in the previous 12 and 24 hours, and freeze conditions within the previous 24 hours were retained in the model. For slumping on both the NE and SW facing sidewall, recent and prolonged rain were important. Specifically, 1, 6, 12, and 24 hour rainfall were retained in both models, with the addition of 3 hour rainfall in the NE facing sidewall slump model. No temperature variables were retained. For channel aggradation (deposition of material in the channel), rain in the prior 12 and 72 hours, and freezing in the prior 24 hours were important, suggesting that freeze-thaw processes loosen the soil, and subsequent rain events carry material into the channel. When rain stops, the material is then deposited in the channel. Interestingly, no viable model could be developed for channel development (erosion) using these parameters. These results will be useful to quantify meteorological controls on gully erosion at short temporal scales.

[pt] O processo de voçorocamento é apontado em muitas pesquisas como consequência do uso do solo, sobretudo da ação antrópica. Entretanto, no médio vale do rio Paraíba do Sul (RJ/SP), tem se observado que áreas sob o mesmo tipo de cobertura e uso do solo apresentam comportamentos diferentes quanto a ocorrência de voçorocas, indicando que existem outros fatores que determinam, de forma mais intensa, a ocorrência desse processo. Desta forma, esse trabalho se propôs a investigar os fatores que podem influenciar a distribuição diferencial do processo de voçorocamento nesta paisagem. Foram selecionadas as bacias mais próximas à calha principal do rio Paraíba do Sul e foram plotadas (em imagem de satélite, com método de fotointerpretação) todas as voçorocas identificadas nesta área. A distribuição espacial de voçorocas foi comparada com outros dados da região (unidades litológicas, cobertura e uso e aspectos morfométricos do relevo). Ao todo foram plotadas 671 voçorocas. Destas 671, 99 (14,7 por cento) foram identificadas como resultado de cortes de estrada e 572 (85,3 por cento) sem apararente relação direta com os cortes de estrada. O resultado da análise evidenciou a predominância deste processo sobre a unidade metassedimentar do gnaisse Paraíba do Sul, caracterizado por um material bastante friável quando decomposto. Além disso, a proximidade da calha principal do rio Paraíba do sul também exerce influência como nível de base regional, determinando o limite do processo erosivo. / [en] Gully erosion have been indicated in many researches as a consequence of the use of land use and land cover. However, it has been observed, in middle Paraíba do Sul river valley, that areas on the same type of current and past land use cover presents different behaviors regarding the occurence of gullies. This indicates that there are other factors that determine the occurenc of this process. The factors that may influence the diferencial distribution of the gully erosion process in this landscape were investigated. Initially, the watersheds closest to the main waterway of the Paraíba do Sul river were selected and all gullies were identified in this área. The spatial distribution of gullies was compared with other data of the region (lithologic units structure, land use cover and morphometric aspects of relief). In all, 671 gullies were plotted. Of these 671, 99 (14,7 percent) were identified as resulto f roads, and 572 (85,3 percent) with no apparent direct relation to this. The result of the analysis evidenced that the predominance of gully erosion is on the metassedimentary lithologic unit of the Paraiba do Sul gneiss. This lithologic unit is characterized by a very friable material when decomposed. In addition, the proximity of the main channel of the Paraiba do Sul river also exerts influences as a regional base level, determining the limit of the erosive process.

Les polygones à coin de glace sont très répandus dans la zone du pergélisol continu. Lorsque le ruissellement d’eau de fonte nivale s’infiltre de façon concentrée dans une cavité, il peut initier le processus de thermo-érosion du pergélisol (notamment des coins de glace) pouvant mener à la formation de ravins. Dans la vallée de Qalikturvik sur l’Ile Bylot (NU, Canada), le développement de ravins de thermo-érosion dans un milieu de polygones à coins de glace entraîne comme impact : i. la réorganisation des réseaux de drainage impliquant un assèchement des milieux humides en marge des chenaux d’érosion, ii. des variations dans le régime thermique et de l’humidité de proche-surface et iii. la prise en charge et le déplacement des sédiments vers l’extérieur du bassin-versant. L’objectif de cette thèse vise à approfondir les connaissances géomorphologiques propres au ravinement par thermo-érosion, d’examiner, caractériser et quantifier les impacts du ravinement (tel que sus-mentionné en i. ii. iii.) et le rôle de celui-ci dans une optique d’évolution du paysage périglaciaire à l’échelle temporelle de l’année à la décennie. Les ravins sont dynamiques : un ravin en particulier déclenché en 1999 et étudié depuis s’érodait à une vitesse de 38 à 50 m/a durant sa première décennie d’existence, pour atteindre une longueur totale de ~750 m et une surface érodée de ~25 000 m² en 2009. Des puits sont localisés près des zones de ravinement actives ; des levées alluviale, mares et polygones effondrés dans les zones stabilisées post-perturbation. Sur la terrasse de polygones recouvrant le plancher de la vallée au site à l’étude, 35 ravins furent identifiés et 1401 polygones furent perturbés avec 200 000 m³ de sols transportés. Une amélioration du drainage, une dégradation de la capacité de rétention de l’humidité, une transition d’un écoulement de ruissellement vers un écoulement canalisé caractérise les aires ravinées et leurs environs. Les polygones intacts sont homogènes d’un à l’autre et dans leurs centres ; les polygones perturbés ont une réponse hétérogène (flore, humidité et régime thermique). Les milieux érodés hétérogènes succèdent aux milieux homogènes et deviennent le nouvel état d’équilibre pour plusieurs décennies. / Ice wedges polygons are very common features characterizing continuous permafrost environments. When concentrated snowmelt runoff recurrently flows into opened frost cracks in ice wedges (or nearby depressions), thermo-erosion of permafrost leading to gullies can occur. In the valley of Qalikturvik on Bylot Island (NU, Canada), rapid development of gullies due to thermo-erosion processes in wet polygons exert the following: i. forced rerouting of drainage networks, changing moisture input in wetlands adjacent to a gullied channel; ii. variation in near-surface thermal regime and moisture; iii. erosion and displacement of thawed soils outside the watershed. The objectives of this thesis are to quantify and widen the understanding of the thermo-erosion gullying geomorphology, the related impacts (as aforementioned in i. ii. iii.) and the role of such erosion in the context of the periglacial landscape evolution on a short to medium timescale. In this study, gullies are active and dynamic: one gully triggered in 1999 (and monitored since then) elongated at a rate varying between 38 and 50 m/y during the first decade following its initiation. Its total length at the end of that decade (1999-2009) was ~750 m for an eroded surface of ~25 000 m². Sinkholes were exclusive to the active zone of a gully where alluvial levees and collapsed polygons were common in the stable zone. Thirty-five gullies were identified over the polygon terrace featuring the valley floor. 1401 polygons were consequently breached due to thermo-erosion resulting in 200 000 m³ of displaced soils and thawed permafrost. Gullied areas were characterized by improved drainage conditions, a reduced capacity to retain moisture and a transition from dominantly surface runoff toward channelized flow. Intact wet polygons were homogeneous between each other and in their center; disturbed polygons were heterogeneous (for moisture, thermal regime and vegetation) following a breach of at least one side. Wetland polygons, when disturbed due to gullying, evolve toward an heterogeneous landscape which will become the new equilibrium for that terrain for decades to come.

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The diploma thesis solves question about sanitation installations and gas installation on the factory floor in Tišnov. The theoretical part deals with draining and cleaning of waste water containing oil products. The work also focuses on possible solutions given specialization. Project part solves sanitation installations and gas installation on the factory floor in the selected variant of the object. This is a large hall with an administrative part.

MENVSC / Department of Geography and Geo-Information Sciences / Human activities on land degradation have triggered several environmental problems especially in rural areas that are under developed. The main aim of this study is to analyse the contribution of different land uses to gully development and sediment load on the Nzhelele River Valley in the Limpopo Province. Data was collected using different methods such as observation, field data techniques and experiments. Satellite digital images, topographic maps, aerial photographs and the sediment load static model also assisted in determining how land use affects gully development and sediment load. For data analysis, the researcher used the following methods: Analysis of Variance (ANOVA), descriptive statistics, Pearson correlation coefficient and statistical correlation methods. The results of the research illustrates that high land use activities create negative changes especially in areas that are highly fragile and vulnerable. Distinct impact on land use change was observed within settlement area (9.6 %) within a period of 5 years. High correlation between soil organic matter and soil moisture (R=0.96) was observed. Furthermore a significant variation (p ≤ 0.6) between the soil organic matter and soil moisture was also observed. A very significant variation (p ≤ 0.003) was observed in bulk density and extreme significant variations (p ≤ 0.0001) were observed in organic matter and soil particle size. The sand mining and agricultural activities has contributed significantly to the amount of sediment load in the Nzhelele River. A high significant amount of total suspended sediment (55.3 %) and bed load (53.8 %) was observed within the agricultural area. The connection which associates the development of gullies to various land use activities determines the amount of sediment load. These results are consistent with other previous research and suggest that land use activities is likely to exacerbate the development of gullies and sediment load in the Nzhelele River Valley