Gully erosion, land uses, water and soil dynamics: a case study of Nazareno (Minas Gerais, Brazil)

Gully erosion is a critical issue worldwide. To correctly associate environmental data (as climate, soil, vegetation cover, topography, etc.) and soil erosion susceptibility with land uses remains a challenge in land management. We examine the returning soil removal of a reclaimed gully in Nazareno city, Minas Gerais’ state (Brazil), comparing field assessment with laboratory experiments using two types of soil (well-developed soil and granite-gneiss saprolite). Both of them showed that macroscopic behavior of soils is connected with microscopic characteristics. Well-developed soil is more erosion resistant than granite-gneiss saprolite, but the surrounding land uses do not respect these differences. These analyses have enabled to explain why this and other gullies in the municipality are apparently stabilized, but soil losses remain occurring. It is demonstrated that urban and rural expansion played the major role in triggering gullies and soil losses.Erosión es un problema crítico en todo el mundo. Este documento evalúa las interacciones de los usos del suelo con la dinámica macroscópica y propiedades microscópicas del suelo frente a la susceptibilidad su erosión. Examinamos la reativación de una cárcava recuperada en la ciudad de Nazareno (Brasil), comparando la evaluación de campo con experimentos de laboratorio utilizando dos tipos de suelo (suelo bien desenvuelto y granito-gneiss saprolito). Ambos demostraron que el comportamiento macroscópico de los suelos esta relacionado con las características microscópicas. Suelo bien desenvuelto es más resistente a la erosión que granito-gneiss saprolito, pero los usos de la tierra de los alrededores no respeta estas diferencias. Estos análisis han permitido explicar por qué este y otras cárcavas del municipio aparentemente se estabilizaron, pero las pierdas de suelo siguen ocurriendo. Se ha demostrado que la expansión urbana y rural desempeñó un papel importante en el desencadenamiento de estas erosiones y pierdas de suelo

Gully erosion, land uses, water and soil dynamics: a case study of Nazareno (Minas Gerais, Brazil)

Gully erosion is a critical issue worldwide. To correctly associate environmental data (as climate, soil, vegetation cover, topography, etc.) and soil erosion susceptibility with land uses remains a challenge in land management. We examine the returning soil removal of a reclaimed gully in Nazareno city, Minas Gerais’ state (Brazil), comparing field assessment with laboratory experiments using two types of soil (well-developed soil and granite-gneiss saprolite). Both of them showed that macroscopic behavior of soils is connected with microscopic characteristics. Well-developed soil is more erosion resistant than granite-gneiss saprolite, but the surrounding land uses do not respect these differences. These analyses have enabled to explain why this and other gullies in the municipality are apparently stabilized, but soil losses remain occurring. It is demonstrated that urban and rural expansion played the major role in triggering gullies and soil losses

Natural and human forcing in recent geomorphic change; case studies in the Rio de la Plata basin

An analysis of geomorphic system`s response to change in human and natural drivers in some areas within the Rio de la Plata basin is presented The aim is to determine whether an acceleration of geomorphic processes has taken place in recent years and, if so, to what extent it is due to natural (climate) or human (land-use) drivers Study areas of different size, socio-economic and geomorphic conditions have been selected: the Rio de la Plata estuary and three sub-basins within its watershed Sediment cores were extracted and dated ((210)Pb) to determine sedimentation rates since the end of the 19th century. Rates were compared with time series on rainfall as well as human drivers such as population, GDP, livestock load, crop area, energy consumption or cement consumption, all of them related to human capacity to disturb land surface Data on river discharge were also gathered Results obtained indicate that sedimentation rates during the last century have remained essentially constant in a remote Andean basin, whereas they show important increases in the other two, particularly one located by the Sao Paulo metropolitan area Rates in the estuary are somewhere in between It appears that there is an intensification of denudation/sedimentation processes within the basin. Rainfall remained stable or varied very slightly during the period analysed and does not seem to explain increases of sedimentation rates observed. Human drivers, particularly those more directly related to capacity to disturb land surface (GDP, energy or cement consumption) show variations that suggest human forcing is a more likely explanation for the observed change in geomorphic processes It appears that a marked increase in denudation, of a ""technological"" nature, is taking place in this basin and leading to an acceleration of sediment supply This is coherent with similar increases observed in other regions (C) 2010 Elsevier B V All rights reservedPlan Nacional de I+D+I, Ministerio de Educacion y Ciencia, Spain[CAMGEO]Plan Nacional de I+D+I, Ministerio de Educacion y Ciencia, Spain[CGL2006-11431]Universidad de Cantabria (Spain)Universidad Nacional de La Plata (Argentina)Universidade de Sao Paulo (USP, Sao Carlos, Brasil)MEC, Spai