Sensitiveness of model to environmental fragilities to multicriterial weighting: physical aspects of watershed of the Alto Uruguay

Modelos de fragilidades ambientais compreendem, de maneira geral, a avaliação de n aspectos (ou fatores) relativos às características locais, usualmente tratadas por técnicos de diferentes áreas constituintes de uma equipe multidisciplinar. Porém a definição dos n aspectos por parte da equipe nem sempre acontece de forma unânime, não raro ocorrendo, no início do processo de avaliação, dúvidas sobre o quanto realmente cada aspecto ou fator (indicador) apresenta-se significativo dentro do modelo de avaliação. Como estudo de caso, foi realizada a sensibilidade das ponderações dos fatores que compõem o método multicriterial AHP (Analytic Hierarchy Process), aplicado na região da bacia hidrográfica do Alto Uruguai. A metodologia consistiu na ponderação sistemática de cada fator constituinte do modelo para posterior consideração quanto a sua influência em relação ao conjunto dos fatores, proporcionando uma avaliação quanto a sua eficácia na identificação de pesos dos fatores em cenários que mostram maior discriminância no conjunto, além de apresentar alternativas na composição dos pesos. Assim, a partir dos resultados da análise, configura-se a importância da realização do estudo da sensibilidade em modelos de fragilidade ambiental aplicados à bacia hidrográfica.Palavras-chave: Análise de sensibilidade; avaliação ambiental; multicritério. AbstractSensitiveness of model to environmental fragilities to multicriterial weighting: physical aspects of watershed of the Alto Uruguay. Environmental fragilities models comprise, generally, the evaluation of n criteria (or factors) on local characteristics, usually handled by technicians from different areas in a multidisciplinary team. However, definition of n aspects by team does not always happen unanimously, often occurring early in the evaluation process doubts whether every aspect or indicator is in fact significant within the evaluation model. As a case study, it was performed the sensitivity of weighting factors that comprising the multicriterial method AHP (Analytic Hierarchy Process) applied to the basin of the Alto Uruguay region. After evaluating the multicriterial method, we applied the sensitiveness analysis to improve the weighting process. Therefore, from the results of this analysis, it sets up the importance of the study of sensitiveness of environmental fragility models for the watershed better understanding.Keywords: Sensitiveness analysis; environmental assessment; multicriterial weighting.AbstractEnvironmental fragilities models comprise, generally, the evaluation of n criteria (or factors) on local characteristics, usually handled by technicians from different areas in a multidisciplinary team. However, definition of n aspects by team does not always happen unanimously, often occurring early in the evaluation process doubts whether every aspect or indicator is in fact significant within the evaluation model. As a case study, it was performed the sensitivity of weighting factors that comprising the multicriterial method AHP (Analytic Hierarchy Process) applied to the basin of the Alto Uruguay region. After evaluating the multicriterial method, we applied the sensitiveness analysis to improve the weighting process. Therefore, from the results of this analysis, it sets up the importance of the study of sensitiveness of environmental fragility models for the watershed better understanding.Keywords: Sensitiveness analysis; environmental assessment; multicriterial weighting

Áreas de Preservação Permanente e seus serviços ambientais

The Permanent Preservation Areas (APP), along watercourses, are determined based on the width of these. However, it is believed that there are more relevant factors, such as environmental services offered by APPs. The present study sought to compile studies that address environmental services from the APPs, such as subsidies for a better understanding on the subject. It was observed that, although there are equations for estimating the minimum width of APPs, some authors argue that the lack of a definitive method for establishing this width that allows for satisfactory protection of the watercourse. Some claim that without studies of the dynamics that occur in the riparian area, there is no way to conclude the distances expressed numerically for APPs are consistent with the principles of preservation for which they propose. Due to different methodologies and parameters involved in the delimitation of APP, are distinct bands of width settings for the same function in the same section of river. Thus, it is considered that one can only make widths indicative of areas to be kept vegetated or revegetated depending on the type of environmental service than expected, without, however, having to determine the proper width to serve simultaneously to all the services.As Áreas de Preservação Permanente (APPs), ao longo dos cursos d’água, são determinadas em função da largura destes. Contudo, acredita-se que há outros fatores que devem ser considerados, entre quais se destacam os serviços ambientais oferecidos pelas APPs. O presente trabalho buscou compilar estudos que tratam dos serviços ambientais oriundos das APPs, a fim de fornecer subsídios para melhor entendimento sobre o assunto. Observou-se que, embora haja equações de estimativa da largura mínima de APPs, há autores que defendem a inexistência de um método definitivo para o estabelecimento desta largura que possibilite uma proteção satisfatória do curso d'água. Alguns autores afirmam que, sem os estudos da dinâmica que ocorre na área ripária, não há como concluir se as distâncias expressas numericamente para APPs são compatíveis com os princípios da preservação para os quais se propõem. Em virtude de diferentes metodologias e dos parâmetros envolvidos na delimitação da APP, encontram-se distintas definições de largura de faixas para uma mesma função, em uma mesma seção de rio. Deste modo, considera-se que se pode apenas fazer indicativos de larguras de áreas a serem mantidas vegetadas ou revegetadas em função do tipo de serviço ambiental que se espera, sem, entretanto, ter a determinação da largura adequada para atender, simultaneamente, a todos os serviços

Fragilidades ambientais do Alto Camaquã e vulnerabilidade dos pecuaristas familiares frente a disponibilidade hídrica

Este trabalho teve como objetivo analisar as vulnerabilidades da pecuária familiar sobre a disponibilidade hídrica, frente ao aumento de temperatura ocasionada pelas mudanças climáticas, da sub-bacia hidrográfica do Alto Camaquã. Este território pertence à parte remanescente de maior valor para a biodiversidade do Bioma Pampa, pois compreende uma região que, por suas características econômicas e socioambientais, ainda mantém um ecossistema a priori estável. O sistema de produção, pecuária familiar, ajuda a manter essas condições, porém sofre determinadas demandas do mercado econômico incompatíveis com seu manejo. As mudanças climáticas e ambientais aceleram os processos de intemperismo, de degradação ambiental, além de influenciar os processos do ciclo hidrológico. Este estudo demonstrou que a disponibilidade hídrica e a resistência do solo são as principais variáveis que tornam o Alto Camaquã um território frágil frente ao aumento de temperatura; e os pecuaristas familiares apresentam-se vulneráveis a estas mudanças por não haver instrumentos de mitigação aos impactos ambientais característicos na região e, tão pouco, estratégias de gestão para propiciar o aumento da sua resiliência

Caracterização da fragilidade ambiental da bacia hidrográfica do Arroio Grande (RS) como subsídio ao planejamento territorial

One of the main tools used by public agencies in preparing the environmental planning is the map of environmental fragility. In order to use geoprocessing technologies to identify areas of bigger and smaller environmental fragility of the Arroio Grande Watershed, it was used the methodology proposed by Ross (1994), The Arroio Grande River Basin is locating between the geographic coordinates 29\ub0 29' 20" and 29\ub0 43' 20" S and 53\ub0 47' 30" and 53\ub0 34' 20" W and has an area of 27,673.77 hectares. Its a medium to high fragility basin, especially as a function of the land use and occupancy as well as its terrain characteristics and soil units. The class of potential fragility with higher representativity is the mean fragility and occurs in an area of 12768.12 hectares. The more representative class of emerging environmental fragility is called the average the mean fragility, present in 54.12% of total basin, presenting itself to 14977.87 hectares. The land use in the class presents the most forests, with 43.47%, followed by class field with 36.52%. Only 4.42% of the area gives strong fragility watershed, of which 89.08% of the total understood by the class of exposed soil, and only 10.86% with the class of irrigated agriculture.Pages: 4072-407

PROTOCOL OF FACTORS ASSESSMENT INFLUENTIAL IN SUSCEPTIBILITY TO EROSION OF RIVER SLOPES

ABSTRACT Actions to conserve rivers must be preceded by an environmental diagnosis, however, beyond the body of water, the adjacent atmosphere must also be characterized by ability of recognizing the human impacts and differentiate them of the natural variation of these ecosystems. This study aimed to develop a rapid assessment protocol (PAR), composed of seven parameters - vegetation, soil texture, part of the river, slope inclination slope gradient, soil depth in slope, stroke width of water course, use and land cover -, assigning them weights 0-4, in order to assess the influence of their categories in susceptibility to erosion of the river slope. The PAR was applied in 40 sampling unities (UA) in the watershed of Arroio Val de Buia in Silveira Martins, RS. From the final result of the PAR it was created erosion susceptibility classes, "stable", "susceptible" and "instable". The t test showed significant differences between the evaluated units and the Hierarchical Cluster Analysis (AHA) distinguished two classes of UA, according to the categories of susceptibility to erosion resulting from PAR. The basic parameters that determined the groupings were: soil, soil depth in slope, vegetation, the stretch of water course and, land use and land cover. We conclude that the PAR is presented as a good rapid assessment tool river, similar to the studied stream, being useful to the environmental planning considering the regional characteristics

PROTOCOL OF FACTORS ASSESSMENT INFLUENTIAL IN SUSCEPTIBILITY TO EROSION OF RIVER SLOPES

ABSTRACT Actions to conserve rivers must be preceded by an environmental diagnosis, however, beyond the body of water, the adjacent atmosphere must also be characterized by ability of recognizing the human impacts and differentiate them of the natural variation of these ecosystems. This study aimed to develop a rapid assessment protocol (PAR), composed of seven parameters - vegetation, soil texture, part of the river, slope inclination slope gradient, soil depth in slope, stroke width of water course, use and land cover -, assigning them weights 0-4, in order to assess the influence of their categories in susceptibility to erosion of the river slope. The PAR was applied in 40 sampling unities (UA) in the watershed of Arroio Val de Buia in Silveira Martins, RS. From the final result of the PAR it was created erosion susceptibility classes, "stable", "susceptible" and "instable". The t test showed significant differences between the evaluated units and the Hierarchical Cluster Analysis (AHA) distinguished two classes of UA, according to the categories of susceptibility to erosion resulting from PAR. The basic parameters that determined the groupings were: soil, soil depth in slope, vegetation, the stretch of water course and, land use and land cover. We conclude that the PAR is presented as a good rapid assessment tool river, similar to the studied stream, being useful to the environmental planning considering the regional characteristics