Geometria dos terraços agrícolas e modelação da instabilidade de vertentes (Vale do Douro - Portugal)

As estruturas construídas para o cultivo da vinha no vale do rio Douro (Portugal) devem adaptar-se às condições do terreno que, genericamente, apresentam declives acentuados, dado o encaixe ao longo do setor português da Meseta Ibérica. Os novos sistemas de terraços onde são implantadas as vinhas usam maquinaria pesada, produzindo uma nova geomorfologia e implicando uma dinâmica natural diferente, associada à instabilidade de vertentes e à erosão dos solos por escorrência.Os novos patamares não permitem a aplicação dos métodos de base estatística, uma vez que não se pode fazer inventário. Mas é possível aplicar modelos matemáticos de base física, já que só se usa o inventário para efeito de validação.Structures built for the cultivation of vineyards in the Douro Valley (Portugal) must adapt to terrain that, generally, have steep slopes, given the deep incision along the Portuguese sector of the Iberian Meseta. The installation of new terracing systems for the vineyards, using heavy machinery, produce a new geomorphology and a different natural dynamics associated with the instability of slopes and soil erosion by runoff. The new geomorphology do not allow the application of statistical based methods for that evaluation since it is not possible to use the inventory. But it is possible to access to susceptibility with the mathematical physically based modelssince the inventory is only used for validation

Validation of landslide susceptibility using a GIS-based statistical model and Remote Sensing Data in the Amzaz watershed in northern Morocco

The main objective of this research is to examine and validate the landslide susceptibility assessment (LSA)results of the spatial probability of landslide occurrence in the Amzaz watershed area in Northern Morocco,setting out to create a helpful agent for the decision-makers of land-use policies. In order to reach the maingoal of this study, two sub-objectives were defined: the presenting of the physiography and the cartographyof the geographical components of the study area, and the analysis of the LSA using a statistical-basedmethod, Information Value Method (IVM), as a criteria required by the Model. Lastly, the validation of theresults through the prediction and success rates was carried out. Landslide susceptibility is the probabilitythat landslides will be generated in the predicted zone depending on local terrain characteristics.Several methods are proposed for landslide susceptibility assessment worldwide. IVM has been applied toprepare the landslide susceptibility map. This paper envisages the definition of the settings of the study areaas well as the geophysical characteristics by means of the acquisition and preparation of predisposing factors,such as the geology, land use and climate and the application of the IVM on LSA using a statistically basedmethod for each subset of the landslide inventory.This study is aimed at a prediction vision for sustainability as an alternative and this is not limited todegradation processes. It also concerns the efforts made to adapt to the impacts and even those of mitigatingchange. The promotion of sustainable development in risk areas requires an effort to analyze and evaluatelocal practices and approaches. This is what we are trying to do through this work, which starts from amethodological basis to validate a model for predicting landslides affecting the Moroccan Central Rif area

Geometria dos terraços agrícolas e modelação da instabilidade de vertentes (Vale do Douro – Portugal)

Structures built for the cultivation of vineyards in the Douro Valley (Portugal) must adapt to terrain that, generally, have steep slopes, given the deep incision along the Portuguese sector of the Iberian Meseta. The installation of new terracing systems for the vineyards, using heavy machinery, produce a new geomorphology and a different natural dynamics associated with the instability of slopes and soil erosion by runoff. The new geomorphology do not allow the application of statistical based methods for that evaluation since it is not possible to use the inventory. But it is possible to access to susceptibility with the mathematical physically based models since the inventory is only used for validation. As estruturas construídas para o cultivo da vinha no vale do rio Douro (Portugal) devem adaptar-se às condições do terreno que, genericamente, apresentam declives acentuados, dado o encaixe ao longo do setor português da Meseta Ibérica.Os novos sistemas de terraços onde são implantadas as vinhas usam maquinaria pesada, produzindo uma nova geomorfologia e implicando uma dinâmica natural diferente, associada à instabilidade de vertentes e à erosão dos solos por escorrência. Os novos patamares não permitem a aplicação dos métodos de base estatística, uma vez que não se pode fazer inventário. Mas é possível aplicar modelos matemáticos de base física, já que só se usa o inventário para efeito de validação

Electrical resistivity and spatial variation in agriculture terraces: statistical correlation between ert and flow direction algorithms

The construction of earthen embankmentterraces in the Douro Region raises a set of problemsrelated to hydrological processes. The main objectiveof this study is the evaluation of the spatial variationof electrical resistivity in agriculture terraces at Dourovalley (Portugal). To achieve this objective, two variablesare analysed, the soil electrical resistivity and the flowdirection algorithm. In a field survey we recorded 13electrical resistivity profiles. The contributing area wascalculated with the algorithms D (Deterministic InfinityFlow) and MFD (Multiple Flow Direction) and the results arethe base of the internal runoff modelling, both supportedby the digital elevation model with a spatial resolutionof 1m2. A correlation between the spatial variation ofthe soil electrical resistivity represented by the standarddeviation of the electrical resistivity for each profile andthe average value of the contributing area coincident witheach profile was established. The electrical resistivitystandard deviation seems to be moderately well correlatedaccording to the D algorithm at about 1m of depth, and ithas a good correlation at 1,5m to 2m of depth with the MFDalgorithm. Taken together, the results show a significantpositive statistical correlation between the electricalresistivity standard deviation and the contributing areas(MFD and D) depending on the soil depth

Nuvens de pontos, classificação de imagens e MDT: Propostas metodológicas

A generalização no acesso a Veículos Aéreos Não Tripulados (VANT) equipados comcâmaras digitais de alta resolução, foi acompanhada por uma evolução de software detratamento de imagens facilitou a aquisição de informação e consequente produção demodelos digitais de elevação. Contudo, este tipo de técnica, ao contrário da tecnologiaLiDAR, não permite, de forma automática a classificação, de acordo com o uso do solo,da nuvem de pontos cotados gerados. Como resultado, os modelos digitais de elevação,representam toda a informação altimétrica relativa aos objetos que se encontram entreo sensor aerotransportado (camara) e o solo. Por vezes é necessário transformarmodelos digitais de elevação em modelos digitais de terreno, neste sentido, utilizandouma classificação supervisionada, testamos vários classificadores no intuito de isolar osGround points dos restantes pontos. Concluímos que o classificador de máxima verossimilhança ICM apresentou os melhores resultados, tornando possível a transformar um Modelo Digital de Elevação num Modelo Digital de Terreno