The Arctic contains a wealth of landforms that are governed by the diurnal and seasonal response of permafrost to climatic and topographic forcings. Of key importance to the process rates of many periglacial landforms is the dynamic behaviour of the active layer, which regulates the transfer of heat and moisture between the atmosphere and permafrost. The strong dependence of periglacial process rates on active layer dynamics makes this geomorphic system particularly sensitive to future increases in Arctic temperatures and precipitation. These increases will continue to degrade permafrost, affecting the distribution and rates of periglacial processes. I develop a landform classification model on Svalbard that reveals solifluction and scree to be the most dominant hillslope processes acting on this landscape, with sediment fluxes greatest in solifluction. A combination of landslide mapping, solifluction modelling and slope stability analysis in Alaska reveals that landslides are coincident with convergent topography on soliflucting hillslopes that have concentrated ground ice at depth. Convergent topography allows for higher moisture availability that feeds the growth, concentration, and development of a large network of ice lenses at the permafrost/active layer boundary. The excess pore pressures generated upon thaw reduces the shear strength of soil at the base of the active layer, causing it to slide downslope along a planar slip surface on top of the unthawed permafrost. Due to a warming Arctic, permafrost is expected to continue thawing, creating an ever more dynamic and deeper active layer. Consequently, the relative regional extent of periglacial landforms in mountainous Arctic environments is expected to change, with Arctic hillslopes becoming more unstable during extreme summer thawing. This will pose a greater hazard to Arctic infrastructure and act as a major force for environmental and geomorphological change.

Resumo: Os projetos de reforma agrária apresentam dificuldades de planejamento para uso e ocupação da terra. Esses problemas afetam a qualidade de vida das famílias, a produtividade e a sustentabilidade ambiental. Isso se deve à carência de estudos interdisciplinares detalhados de diagnósticos e zoneamentos ambientais para implantação, desenvolvimento e gestão desses assentamentos. Assim, o objetivo principal desse estudo é estabelecer o zoneamento geoambiental no assentamento rural Pirituba II (Itapeva/Itaberá/SP) e analisar o uso desse instrumento para melhorar os projetos de reforma agrária que visem a sustentabilidade socioambiental. Para isso, foram realizadas fotointerpretação de fotos aéreas (escala 1:25.000) e verificações em campo para detalhar as informações ambientais básicas de drenagem, geologia estrutural, de unidades fisiográficas, e pedológicas. Essas informações permitiram a compreensão da evolução e dinâmica da paisagem. A partir da caracterização das unidades fisiográficas colúvio-aluvionares da área foram estabelecidos os fatores e processos endógenos e exógenos que resultaram na formação das paisagens. Isto permitiu estabelecer as zonas geoambientais (unidades aloestratigráficas). Essas foram divididas em subzonas geoambientais pela análise estrutural e fisiográfica, para posteriormente determinar as potencialidades e limitações de tais unidades. Dessa forma, mapas temáticos foram elaborados quanto à: suscetibilidade à erosão, indicação de áreas para proteção ambiental e adequação a culturas anuais. A aplicação do zoneamento geoambiental no assentamento Pirituba II forneceu um estudo detalhado e integrado do meio físico para planejamento local visando a sustentabilidade socioambiental. Portanto, esse zoneamento pode ser uma ferramenta útil para a gestão territorial e melhoria dos projetos de reforma agrária. / Abstract: The environmental diagnostic studies that aim planning for land reform settlements are few and still present some gaps. These affect the life quality of families, productivity and environmental sustentability. Geoenvironmental zoning is based on the integration of physical aspects, and for this reason it may contribute with information that will be used for the environmental analysis of these settlements. The aim of the present study is to evaluate the geoenvironmental zoning applied to the Pirituba II Settlement (Itapeva/Itaberá/SP) as a reliable tool and instrument for the definition of lines that can help in the sustainable implementation of land reform projects, as much by the social view as by the environmental focus. For this the drainage, structural geology, physiographic unities and pedological basic environmental information were detailed through field and laboratory works (aerial photointerpretation). This information have enabled better undestanding of the landscape dynamic and evolution. Physiographic characterization for colluvial and alluvial units of the studied area permitted to establish the factors and processes, both endogenetic and geomorphic, that resulted in the landscape formation. The geoenvironmental zoning was defined by this purpose, which generate subdividing operations into structural and physiographic analysis, for as much as the potentiality and limitation determination of them as entities. The following thematic maps were obtained, therefore: erosion vulnerability, environmental protection indication and agricultural annual rotation. The results of the geoenvironmental zoning work in the Pirituba II Settlement allowed the definition of environmental planning detailed strategies in agreement with sustainable reality. / Orientador: Jairo Roberto Jiménez-Rueda / Coorientador: Gerd Sparovek / Banca: Rualdo Menegat / Banca: Ariovaldo Umbelino de Oliveira / Mestre

Resumo: A área escolhida para a realização deste trabalho foi o município de Itápolis, o qual se localiza na porção oeste do estado de São Paulo. A escolha de Itápolis está relacionada à ausência de trabalhos vinculados à temática ambiental para a região em que o mesmo se insere, os quais se fazem necessários em decorrência da intensa atividade agrícola que ali se desenvolve. Neste contexto, o objetivo deste trabalho foi realizar um levantamento das características ambientais da área e, a partir da análise destas, elaborar o zoneamento geoambiental do município com base na proposta de Mateo Rodriguez (1994) a qual possibilita uma interpretação do meio através da análise sistêmica. Através dessa proposta metodológica o município foi dividido em diversas unidades e para cada uma delas estabeleceu-se o estado ecológico baseado na relação entre a capacidade de uso potencial e a função sócio-econômica atual. A aplicação desta metodologia se mostrou satisfatória, sendo que a mesma forneceu informações relevantes em relação às fragilidades ambientais da área e concomitantemente possibilitou a realização de uma análise geoambiental para o município, cujo maior problema identificado foi a intensa ação de processos erosivos, com formas erosivas já instaladas em decorrência do uso da terra sem que se empregue práticas conservacionistas. / Abstract: The chosen area for accomplishment of this work was the Itápolis municipality, located in the west portion of the Sao Paulo State. The choice was due to absence of environmental works in the region, necessary because of intense agricultural activities. In this context, the goal was to carry out a survey of environmental features of the area and after analysis, to elaborate environmental zoning of the municipality, based on Mateo Rodriguez (1994) proposal which makes interpretation through system analysis. Through this methodological proposal, the municipality was divided in diverse units and each one of them, the ecological status is established according to capacity of potential use and present social and economic function. The application of this methodology was satisfactory, supplying relevant environmental vulnerability data making possible an environmental analysis of the municipality whose major problems are the intense erosive processes in course as a result of land use without conservatives practices. / Orientador: Cenira Maria Lupinacci da Cunha / Banca: Regina Célia de Oliveira / Banca: Antônio Carlos Tavares / Mestre

Estuaries are among the most biologically productive ecosystems on the planet, per unit area, with intertidal habitats and particularly saltmarshes providing a variety or ecosystem services and supporting large numbers of both primary and secondary producers. These habitats are globally important and are found throughout tropical to temperate climates. Micro-tidal estuaries are found throughout the world and particularly sensitive to sea-level rise, as they are limited in their ability to adjust and are considered vulnerable to future changes .Hence, at a broad scale, understanding the drivers and mechanisms of saltmarsh change in micro-tidal systems is crucial in aiding decision making in future coastal management. This thesis explores the drivers and mechanisms of saltmarsh change through the development of a conceptual model, which is then tested using Poole Harbour, UK as a case study site. The potential drivers of saltmarsh change were investigated using a multidisciplinary approach, combining a GIS historic change analysis utilising aerial photography, charts and maps, a bathymetric analysis of the harbour morphology and a 2D hydrodynamic TELEMAC model. Spartina anglica rapidly colonised the Harbour at the end of the 19th Century increasing the saltmarsh area from approximately 120ha to over 900ha during the 1920’s, after which there was a decline in area that has continued to present day However, saltmarsh extent in 2005 was still approximately three times the extent prior to the colonisation of Spartina anglica. Poole Harbour is large and dendritic and spatially within the Harbour separate tributaries exhibit clearly distinct saltmarsh erosion and accretion trends. Accretion was seen to occur in relatively sheltered locations with short fetches, fronted by high mudflats, in areas that are flood dominant both in terms of hypsometry as well as tidal peak flow and slack duration. Erosion was seen to occur in relatively exposed areas where the marsh top and fringing mudflats are significantly lower and local sediments have a lower shear velocity than in accretionary regions. Saltmarsh erosion tends to occur in morphologically ebb dominant areas but not exclusively, suggesting multiple drivers are in operation. Poole Harbour is used in this study as an example of a wider global problem. At a broad scale, observations emphasise that saltmarsh changes occurring elsewhere in the UK, and potentially elsewhere in the world, may be more complex than often portrayed. Highlighting the need for detailed case by case studies, that use all the data available over a sufficient time period. Multiple drivers of change control the net evolution of saltmarsh in Poole Harbour and this is likely to be a widespread conclusion for other estuaries globally.

Nature ecosystems are always complex, full of uncertainties and nonlinear changes. These changes are sometimes catastrophic, and many ecosystems have already been altered from their natural state as a result of human activities. Therefore, abrupt changes are likely to happen, the consequences of which can be irreversible. It becomes urgent to (i) further understand the features of complex ecological systems, and (ii) to identify yearly warning signals (EWS) to allow prediction of catastrophic transitions. This thesis aims for an understanding of one such example of a complex ecological system, i.e. Erhai Lake, Yunnan Province, China, and to determine the EWS in this ecosystem. This thesis focuses on the process of eutrophication in Erhai Lake, using two cores from the lake and a training set from Yunnan province, SW China. The study employed multiple techniques including monitoring, palaeolimnological proxies and modelling. The ideas of feedbacks, resilience and thresholds from complex ecological system theory are used to interpret the lake’s eutrophication process. Fossil diatom data is mainly employed to calculate the EWS for the lake’s ecosystem transition. The conclusions have been supported with a minimal model which is written with STELLA software. The main findings include: 1. The alternative stable states in the training set may affect the accuracy of diatom-based transfer functions. 2. The resilience of the lake’s ecosystem decreased due to the intensification of human activities, and the lake crossed a threshold at around 2001 due to a new positive feedback mechanism. 3. The lake was in a ‘flickering’ state between 1980-2000. Rising variance could be considered as an indicator of EWS but it was most likely caused by flickering rather than ‘critical slowing down’ in these noise-induced critical transitions. 4. The minimal model shows that flickering states can be simulated, and the rising variance due to flickering is also likely to predict the critical transitions in the simulated system. The mutual authentication between palaeo- data and the minimal model can deeply improve the understanding of a complex system, and explanation of complex theories. This work firstly considered the alternative stable states in a training set and presented EWS in a real natural ecosystem. Our findings suggest that rising variance can be seen as a warning signal in a system; therefore, it can be applied for intervention purposes in critical transitions in real ecosystems.

Marine Protected Areas (MPAs) are recognised globally as effective tools for protecting valuable and vulnerable marine ecosystems (habitats, species and communities), maintaining the biological diversity, and safeguarding the associated historical and cultural resources. MPAs accommodate local communities and regulate the different uses of the sea, fostering more sustainable use of marine resources. Moreover, MPAs are increasingly being used as environmental laboratories, enabling a greater scientific understanding of marine systems. In the Mediterranean Sea about a hundred of MPAs have been designated during the last decades, all but one of which are in coastal areas. This study develops a new way of using RS techniques tailored for the monitoring and management of Mediterranean MPAs. The advance in satellite Remote Sensing (RS) technologies has made possible to look at the MPAs not only by means of discrete in situ surveys but rather on the basis of a “synoptic” and repeated view. The primary aim of this thesis was to establish how the satellite sensors can be successfully used and whether RS provides reliable tools for monitoring and managing Mediterranean MPAs. The study aimed specifically at describing and identifying, by means of passive remote sensors, the spatial and temporal scale of the bio-physical processes occurring in Mediterranean MPAs. Observations retrieved by ocean colour and thermal infra-red sensors, for a range of MPA study sites, were used to depict system functioning by the analysis of the prevailing spatial and temporal variations of the geophysical parameters and biophysical conditions. The seasonal variations of the ecological indicators (i.e. phytoplankton blooms and thermal trends) were analysed over various MPAs located in different regions of the Mediterranean basin, and different biooptical algorithms were tested in a coastal MPA. The short-term and long-term monitoring (interannual) of the ecological indicators is key to elucidating trends and modifications in the biogeochemical balance of the basin possibly caused by environmental changes which could potentially affect the MPA’s resilience. Consequently it is now possible to monitor MPAs easily and at low cost, by integrating RS with the traditional sampling methodologies to work towards safeguarding of valuable marine habitats and species. RS should be considered as key tool that fosters the ecosystem-based management.

Production efficiency models (PEMs) have been developed to aid with the estimation of terrestrial ecosystems productivity where large spatial scales make direct measurement impractical. One of the key datasets used in these models is the fraction of photosynthetic active radiation absorbed by vegetation (FAPAR). FAPAR is the single variable that represents vegetation function and structure in these models and hence its accurate estimation is essential. This thesis focused on improving the estimation of FAPAR and developing a new PEM model that utilises the improved FAPAR data. Foremost, the accuracy of operational LAI/FAPAR products (i.e. MGVI, MODIS LAI/FAPAR, CYCLOPES LAI/FAPAR, GLOBCARBON LAI/FAPAR, and NN-MERIS LAI TOC algorithm) over a deciduous broadleaf forest was investigated. This analysis showed that the products varied in their prediction of in-situ FAPAR/LAI measurements mainly due to differences in their definition and derivation procedures. The performance of three PEMs (i.e. Carnegie-CASA, C-Fix and MOD17GPP) in simulating gross primary productivity (GPP) across various biomes was then analysed. It was shown that structural differences in these models influenced their accuracy. Next, the influence of two FAPAR products (MODIS and CYCLOPES) on ecosystem productivity modelling was analysed. Both products were found to result in overestimation of in-situ GPP measurements. This was attributed to the lack of correction for PAR absorbed by the non-photosynthetic components of the canopy by the two products. Only PAR absorbed by chlorophyll in the leaves (FAPAR chlorophyll) is used in photosynthesis and hence it was hypothesised that deriving and using this variable would improve GPP predictions. Therefore, various components of FAPAR (i.e. FAPAR canopy, FAPAR leaf and FAPAR chlorophyll) were estimated using data from a radiative transfer model (PROSAIL-2).The FAPAR components were then related to two sets of vegetation indices (i.e. broad-band: NDVI and EVI, and red-edge: MTCI and CIred-edge). The red-edge based indices were found to be more linearly related to FAPAR chlorophyll than the broad-band indices. These findings were also supported by data from two flux tower sites, where the FAPAR chlorophyll was estimated through inversion of net ecosystem exchange data and was found to be better related to a red-edge based index (i.e. MTCI).Based on these findings a new PEM (i.e. MTCIGPP) was developed to (i) use the MTCI as a surrogate of FAPAR chlorophyll and (ii) incorporate distinct quantum yield terms between the two key plant photosynthetic pathways (i.e. C3 and C4) rather than using species-specific light use efficiency. The GPP predictions from the MTCIGPP model had strong relationship with the in-situ GPP measurements. Furthermore, GPP from the MTCIGPP model were comparable to the MOD17GPP product and better in some biomes (e.g. croplands). The MTCIGPP model is simple and easy to implement, yet provides a reliable measure of terrestrial GPP and has the potential to estimate global terrestrial carbon flux.

Some climate models are still lacking features such as dynamical modelling of ice sheets due to their computational cost which results in poor accuracy and estimates of e.g. sea level rise. The need for low-cost high-order models initiated the development of the First-Order Stokes (or Blatter-Pattyn) model which retains much of the accuracy of the full-Stokes model but is also cost-effective. This model has proven accurate for ice sheets and glaciers with frozen bedrocks, or no-slip basal boundary conditions. However, experimental evidence seems to be lacking regarding its accuracy under sliding, or stress-free, bedrock conditions (ice-shelf conditions). Hence, it became of interest to investigate this. Numerical experiments were set up by formulating the first-order Stokes equations as a variational finite element problem, followed by implementing them using the open-source FEniCS framework. Two types of geometries were used with both no-slip and slip basal boundary conditions. Specifically, experiments B and D from the Ice Sheet Model Intercomparison Project for Higher-Order ice sheet Models (ISMIP-HOM) were used to benchmark the model. Local model errors were investigated and a convergence analysis was performed for both experiments. The results yielded an inherent model error of about 0.06% for ISMIP-HOM B and 0.006% for ISMIPHOM D, mostly relating to the different types of geometries used. Errors in stress-free regions were greater and varied on the order of 1%. This was deemed fairly accurate, and probably enough justification to replace models such as the Shallow Shelf Approximation with the First-Order Stokes model in some regions. However, more rigorous tests with real-world geometries may be warranted. Also noteworthy were inconsistent results in the vertical velocity under slippery conditions (ISMIPHOM D) which could either be due to coding errors or an inherent problem with the decoupling of the horizontal and vertical velocities of the First-Order Stokes model. This should be further investigated. / Vissa klimatmodeller saknar fortfarande funktioner så som dynamisk modellering av istäcken på grund av dess höga beräkningskostnad, vilket resulterar låg noggrannhet och uppskattningar av t.ex. havsnivåhöjning. Behovet av enkla modeller med hög noggrannhet satte igång utvecklingen av den s.k. Första Ordningens Stokes (eller Blatter-Pattyn) modellen. Denna modell behåller mycket av noggrannheten i den mer exakta full-Stokes-modellen men är också väldigt kostnadseffektiv. Denna modell har visat sig vara noggrann för istäcken och glaciärer med frusna berggrunder eller s.k. no-slip randvillkor. Experimentella bevis tycks dock saknas med avseende på dess noggrannhet under glidning, eller stressfria, berggrundsförhållanden (t.ex. vid ishyllor). Därför ville vi undersöka detta. Numeriska experiment upprättades genom att formulera Blatter-Pattyn ekvatonerna som ett variationsproblem (via finita elementmetoden), följt av att implementera dem med hjälp av den öppna källkoden FEniCS. Två typer av geometrier användes med både glidande och stressfria basala randvillkor. Specifikt användes experiment B och D från Ice Sheet Model Intercomparison Project for Higher-Order ice sheet Models (ISMIP-HOM) för att testa modellen. Lokala fel undersöktes och en konvergensanalys utfördes för båda experimenten. Resultaten gav ett modellfel på ca 0,06 % för ISMIP-HOM B och 0,006 % för ISMIP-HOM D, vilka var mest relaterade till de olika typerna av geometrier som användes. Fel i stressfria regioner var större och varierade i storleksordningen 1 %. Detta ansågs vara ganska noggrant och sannolikt tillräckligt för att ersätta modeller så som Shallow Shelf Approximationen med Blatter-Pattyn-modellen i vissa regioner. Dock krävs mer noggranna tester med mer verkliga geometrier för att dra konkreta slutsatser. Också anmärkningsvärt var motsägande resultat i den vertikala hastigheten under glidande förhållanden (ISMIP-HOM D) som antingen kan ha berott på kodningsfel eller ett modelproblem som härstammar utifrån särkopplingen mellan den horizontella- och den vertikala hastigheten i Blatter-Pattyn-modellen. Detta bör undersökas vidare.

The Wealden ghyll woodlands are associated with unique plant assemblages that include nationally rare bryophyte species with oceanic affiliations. The identification and monitoring of this type of 'priority' habitat, recognised as important in terms of regional and national biodiversity, is a central facet of the UK Biodiversity Action Plan (UKBAP). Despite the acknowledged importance of ghyll woodlands for non-vascular plant species, previous studies attempting to examine and characterise the ghyll woodlands have neglected to include these bryophyte communities. This research identifies and characterises the Wealden ghyll woodlands through an examination of the spatial and temporal distributions of bryophyte and flowering plant species. The research also seeks to provide baseline data against which biodiversity levels can monitored. In order to identify and contextualise the importance of ghyll woodland in terms of regional biodiversity, survey data was collected from other types of ancient woodland throughout the region for comparative analysis. The study involved the collection of species and environmental data from a total of 1440 random quad rats from 60 survey sites situated throughout the Weald, as well as the use of archive survey data collected during two 20 year periods (1951-1970 and 1976-1995). A number of statistical approaches including general linear modelling, ANOSIM, MannWhitney U and Spearman rank correlation analysis were used to identify the environmental correlates of spatial and temporal changes in species distributions. Spatial analysis indicated that ghyll woodland is restricted to the stream valleys themselves which were significantly richer in bryophyte and flowering plant species than the surrounding woodlands. NVC classifications assigned to the ghylls indicated the presence of 'oceanic' plant communities that are associated with damp, humid microclimatic conditions. A number of authors have explained the presence of oceanic bryophytes within the ghylls as being the result of a damp, humid microclimate present within the stream valleys. However, the study found no significant differences between climatic conditions within the ghyll valleys and those in the surrounding ancient woodlands. ANOSIM analysis indicated that community composition was influenced by site substrate, with clay and sandstone ghyll woodlands containing significantly different plant communities. Chi-squared analysis identified a temporal increase in the ratio of oceanic bryophytes and ancient woodland indicator flowering plant species during the study period. Analysis of Ellenberg indicator values indicated a move towards more shadetolerant plant communities within the ghyll woodlands. The patchily distributed ghyll woodlands were examined for signs of habitat fragmentation through genetic analysis of the bryophyte Conocephalum conicum (Great Scented Liverwort) using the random amplification polymorphic DNA technique (RAPD). Wright's fixation index (FST) and Nei 's coefficient of gene variation (GST) both indicated a loss of genetic diversity characteristic of genetic isolation. A Mantel test based on Nei 's genetic distance values indicated that the genetic isolation observed was not correlated with the geographical distance between populations. The study indicated that temporal changes are occurring in the composition of ghyll woodland plant communities and that bryophyte populations are displaying symptoms of genetic isolation. The study illustrates the importance of some form of monitoring program if the biodiversity value of these sites is to be maintained.

ALMEIDA, Thiara Messias de. Análise Geossistêmica Aplicada ao Estudo da Fragilidade Ambiental na Bacia Hidrográfica do Rio São João de Tiba-BA. 2014. 267 f. Tese (Doutorado em geografia)- Universidade Federal do Ceará, Fortaleza-CE, 2014. / Submitted by Elineudson Ribeiro (elineudsonr@gmail.com) on 2016-06-14T17:29:13Z No. of bitstreams: 1 2014_tese_tmalmeida.pdf: 24484328 bytes, checksum: a5b8846678a86d1ba8ae9d88621a4804 (MD5) / Approved for entry into archive by José Jairo Viana de Sousa (jairo@ufc.br) on 2016-06-14T17:49:21Z (GMT) No. of bitstreams: 1 2014_tese_tmalmeida.pdf: 24484328 bytes, checksum: a5b8846678a86d1ba8ae9d88621a4804 (MD5) / Made available in DSpace on 2016-06-14T17:49:21Z (GMT). No. of bitstreams: 1 2014_tese_tmalmeida.pdf: 24484328 bytes, checksum: a5b8846678a86d1ba8ae9d88621a4804 (MD5) Previous issue date: 2014 / The watershed is understood as a complex system that integrates elements natural, socioeconomics and cultural. The objective of research was to assess the anthropogenic changes in the dynamics of landscape the River Basin São João de Tiba-BA and its interference in the fragility of environmental systems. The basin of 178. 071 hectares, is inserted in the Region of Extreme South Bahia, which was incorporated into the "development" of economic and private megaprojects like cellulose of extensive territorial occupation that this region has experienced, resulting in severe exploitation of natural resources and intense changes in the landscape. Thus, to understand the natural dynamics and the processes of land use and occupation were performed analysis physiographic, morphometric, socioeconomic diagnosis and characterization of the evolution of the use of land, identifying the major impacts of space appropriation process. To meet the proposed objectives, was adopted the scale 1:100.000. The research involved the use of cartographic techniques and remote sensing, through GIS. For this, we used radar image (SRTM and ASTER), and satellite images Landsat TM 5, information collected in fieldwork, and data socioeconomic nature. The data generation and preparation of maps was performed in SIG ArcGIS 10. The integrated analysis of the environment can be inferred that the area is characterized, mostly by plan relief of the Coastal Tablelands of Barriers Group, which originated evolved soils as Yellow Latosols, naturally covered by a rainforest that were gradually replaced. The basin comprises nine different environmental systems. The geo-environmental characteristics of the area were attractive for the development of the main forms of anthropism that changed the landscape and turned it into two types of scenarios: the of pasture and of eucalyptus. The use of land for pasture concentrates most of the arable land, and what else disrespects environmental legislation. The plantation of eucalyptus is agricultural use with the highest growth in the period analyzed, meanwhile, the remaining forest areas were reduced by 63%. The forms of land use practiced in the basin contributed to the increase in environmental degradation processes and, consequently, increasing its Environmental Fragility. It is hoped that the research can collaborate with the area of systems analysis in watersheds as a subsidy to the Environmental Planning. / A bacia hidrográfica é entendida como um sistema complexo que apresenta de forma integrada elementos naturais, socioeconômicos e culturais. O objetivo da pesquisa foi verificar as mudanças antropogênicas na dinâmica da paisagem da Bacia Hidrográfica do Rio São João de Tiba-BA e sua interferência na fragilidade dos sistemas ambientais. Trata-se de uma bacia de 178. 071 ha, inserida na Região do Extremo Sul da Bahia, a qual foi incorporada ao processo de “desenvolvimento”, de megaprojetos econômicos e privados de extensiva ocupação territorial como a celulose, resultando em acentuada exploração de recursos naturais e intensas transformações na paisagem. Assim, para entender a dinâmica natural e os processos de uso e ocupação da terra foram realizadas análises fisiográficas, morfométricas, diagnóstico socioeconômico, caracterização da evolução dos usos do solo e mapeamentos síntese da fragilidade ambiental, identificando os principais impactos decorrentes do processo de apropriação do espaço. Para atender os objetivos propostos, adotou-se a escala de 1:100.000. A pesquisa envolveu o uso de técnicas cartográficas e sensoriamento remoto, através do geoprocessamento. Para tal, utilizou-se imagens de radar (SRTM e ASTER), imagens de satélite do sistema Landsat 5 TM, informações coletadas em trabalhos de campo, e informações de natureza socioeconômica. A geração dos dados e confecção dos mapas foi realizada no SIG ArcGis 10. A análise integrada do meio físico permite inferir que a área é caracterizada, em sua maior parte, pelo relevo plano dos Tabuleiros Costeiros do Grupo Barreiras, que deram origem a solos evoluídos como os Latossolos Amarelos, recobertos naturalmente, por uma mata úmida que foi paulatinamente substituída. A bacia comporta nove sistemas ambientais diversos. As características geoambientais da área foram atrativas para o desenvolvimento das principais formas de antropismo que modificaram a paisagem e a transformaram em dois tipos de cenários: o do pasto e o do eucalipto. O uso do solo com pastagens concentra a maior parte das terras agricultáveis, e o que mais desrespeita a legislação ambiental. A silvicultura é o uso agrícola que apresentou maior crescimento no período analisado, enquanto isso, as áreas com remanescentes florestais foram reduzidas em 63%. As formas de uso da terra praticadas contribuíram para o aumento dos processos de degradação ambiental e, consequentemente o aumento da sua fragilidade. A pesquisa contribui com a área da análise sistêmica em bacias hidrográficas como subsídio ao Planejamento Ambiental.