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Abstract:The Civil Defense in Brazil needs to identify and differentiate floods and flash floods for the official registry. This study aims to quantitatively define and differentiate between floods and flash floods. Floods and flash floods are characterized by factors including the speed of water level rise and water flow; the hydrological response time to a rainfall event and the extension of the flood affected area. The hydrological definitions are ambiguous and make it difficult to distinguish between a flood and flash flood event. Even though some papers have mentioned that flash floods occur within 6 hours after an intense rainfall event, there is still certain subjectivity. This study proposes the use of the Operation Efficiency Index (OEI) as a quantitative means to distinguish between a flood and flash flood event. The OEI is defined as the rate of the time of flood concentration (Tc) to the operational response time (To) in the institution-community system. Tc and To are associated with environmental and human factors, respectively. When the OEI value is smaller than one, then flash floods occur. Otherwise the event can be defined as a flood.

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O presente trabalho apresenta uma revisão conceitual sobre a Hidrogeomorfologia. Esta ciência foi conceitualmente proposta em 1973 e desde lá vem sido desenvolvida e aplicada em diversas pesquisas. A Hidrogeomorfologia pode ser considerada como a união entre a Hidrologia e a Geomorfologia, sendo que a maneira como esta união ocorre ainda não é muito clara. São apresentadas e analisadas diversas pesquisas que se intitulam de hidrogeomorfológicas e denotam que ainda não há um consenso metodológico e conceitual sobre esta nova ciência. Por fi m, o presente trabalho analisou a formação conceitual da Hidrogeomorfologia, seus princípios, processos, aplicações e o seu objeto.

In this paper, a stormwater fee specifically for small municipalities was developed through a simplification of the Equivalent Residential Unit (ERU) system, which is the main method applied in the United States. The Simplified ERU is based on the amount of impervious area and the fee considers the operations and maintenance costs, besides having a single class of billing. It was applied in Santo Amaro da Imperatriz city, located in the southern region of Brazil, which can be classified as a small city. The value of the Simplified ERU (294.32 m2) was similar to the average impervious area in the United States (269.42 m2) and it was equivalent to $0.28 per square meter (within the range of other countries' fees). The method proved to be a feasible and rapid technique for funding stormwater services, and its simplicity allows its application in different locations. This funding model can generate revenue to address current stormwater problems, such as the lack of funding for existing drainage infrastructure, and contribute to downstream flooding reduction. This paper also intends to encourage discussion about the methods for designing a stormwater fee in the academic community, which is still incipient.

In Santa Catarina State (Brazil), Rio dos Cedros is one of the cities that suffered from natural disasters triggered by very intense rainfall in November 2008. According to the Municipal Civil Defense, this event caused economic losses of US$2.1 million and 96 homeless, directly affecting 90% of the municipal population. The principal phenomenon responsible for these disasters was the debris flow. In this context, field surveys were conducted throughout the city in order to investigate the possibility for houses to be affected by landslides and debris flows. After the preliminary evaluation, two cases of debris flow whose extensions were over 1 km were chosen for a more detailed survey. The objective of the present study was to analyze the meteorological and geomorphic aspects of these cases. The total rainfall in Rio dos Cedros in November 2008 and the entire year of 2008 were 644 mm and 2509 mm, respectively. An analysis of the daily rainfall during October and November 2008 and the debris flow occurrence time indicates that the factor triggering debris flows in Rio dos Cedros in 2008 was the accumulated rainfall, not its intensity. Two debris flows analyzed in the present study had different geomorphic conditions, one being confined in the channel and showing ordinal debris flow (Debris A), and the other unconfined, presenting the debris avalanche feature (Debris B). The larger density of clastic blocks was observed at the depositional area of Debris B. Both the localities are characterized with migmatite. Topographic analysis showed that the volume of the mass movement is related with topographic parameters (elevation difference and travel distance). This relationship implies that the two cases of Rio dos Cedros had similar behavior to other cases reported in temperate and cold regions. It is, therefore, concluded that there is geomorphic control on

Os escorregamentos são processos naturais que podem trazer diversos impactos ambientais, sociais e econômicos.A identificação e mapeamento de áreas suscetíveis a escorregamentos são procedimentos importantes no gerenciamento de bacias hidrográficas. O uso de modelos de estabilidade de encostas auxilia na gestão da problemática envolvendo os escorregamentos, mas frequentemente negligenciam o efeito da vegetação. Este trabalho apresenta uma metodologia para analisar o efeito da vegetação em modelos de estabilidade de encostas. Em primeiro lugar, parâmetros relacionados a vegetação foram inseridos no equacionamento do Fator de Segurança (FS). A partir de análise de sensibilidade, verificou-se quais parâmetros possuem maior influência na estabilidade. Posteriormente, o modelo SHALSTAB foi modificado, inserindo os parâmetros mais relevantes, e aplicado na Bacia do rio Cunha. Os efeitos mecânicos, gerados pela presença da vegetação, inseridos na equação do FS são: coesão das raízes (cr); sobrecarga gerada pelo peso da vegetação (Sw); tensão cisalhante oriunda da ação do vento nas copas das árvores (Ve). Observou-se que cratua no sentido de aumentar a estabilidade da encosta e sua influência é a mais significativa dentre os parâmetros analisados e é maior em solos rasos, diminuindo com o aumento da profundidade. O parâmetro Sw atua na redução da estabilidade da encosta e exerce maior influência em solos

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