As plantas aquáticas são estudadas como um efeito do desequilíbrio causado pela poluição e/ou alagamento dos rios. A quantidade excessiva de plantas, conseqüente desse desequilíbrio, dificulta a navegação e a produção de energia elétrica. O objetivo deste trabalho foi identificar as principais plantas aquáticas do rio Tietê e relacioná-las com a turbidez da água dos diferentes reservatórios. Foram avaliados todos os focos de vegetação aquática emersa, flutuante e submersa, presentes em cada reservatório, em toda a sua extensão, sendo consideradas como importantes as espécies que apresentaram o caráter dominante. Foi observado que os represamentos apresentam problema de plantas aquáticas e a qualidade da infestação varia entre os reservatórios. Foram consideradas como dominantes as seguintes espécies: Brachiaria mutica, Brachiaria subquadripara, Eichhornia crassipes, Egeria densa, Egeria najas, Enidra sessilis e Typha angustifolia. Observou-se que houve uma tendência de maior ocorrência de plantas flutuantes e emersas (marginais) nos reservatórios com maior turbidez e de plantas submersas naqueles com menor turbidez. Para as duas braquiárias, observou-se que a freqüência das espécies aumentou com o aumento da turbidez até o limite de 34,93 NTU. O aguapé ocorreu com altos índices de freqüência (acima de 50%) em todos os reservatórios do rio Tietê, independentemente das características da água. Em se tratando das egérias, a freqüência das espécies aumentou gradativamente com a redução da turbidez e a taboa não apresentou uma relação com o índice estudado. A espécie E. sessilis se mostrou bastante dependente da qualidade da água, tendo sua freqüência aumentada com o aumento da turbidez.<br>Aquatic plants are studied as an effect of pollution unbalance and/or river flooding. The excessive amount of plants,as a consequence of such unbalance, hinders navigation and electric power production. The objective of this work was to identify the main aquatic plants of the Tietê River and to relate them with water turbidity of the different reservoirs. All the foci of aquatic immersed, floating and submerged vegetation in each reservoir were evaluated in all their extension. Those species presenting a dominant character were considered important.The reservoirs were found to present aquatic plant problems with the quality of infestation varying among the reservoirs. The following species were considered to be dominant: Brachiaria mutica, Brachiaria subquadripara, Eichhornia crassipes, Egeria densa, Egeria najas, Typha angustifolia and Enidra sessilis.There was a tendency for a greater occurrence of floating and submerged (marginal) plants in the reservoirs with greater turbidity and for a larger occurrence of submerged plants in reservoirs with less turbidity. For the two Brachiarias it was observed that the frequency of the species increased with the increase of turbidity up to the limit of 34.93 NTU. E. crassipes occurred with high frequency indexes (above 50%) in all the Tietê River reservoirs, independent of the characteristic of the water. For Egerias, frequency increased gradually with reduced turbidity and T. angustifolia did not present a relationship with the studied index. The species E. sessilis was found to be rather dependent on the quality of the water,its frequency increasing with increased turbidity.

D. Kaimowitz, 'Cuatro medio verdales: la relacion bosques y agua en Centroamericana', 2001 | This paper looks at four &#8220;half-truths&#8221; about the relations between forests and water in Central America. The first is that deforestation has reduced rainfall in certain regions of Central America. The second is that forest help to maintain dry season stream flow. The third is that deforestation has led to more intense flooding. The fourth is that the region&#8217;s hydroelectric reservoirs and the Panama Canal are rapidly becoming sedimented. As the name implies, the article argues that each of these has some elements of truth but other aspects that are myths. The author emphasizes that even though some of these claims are myths action still needs to be taken to avoid inappropriate deforestation and forest degradation

Climate change is at the top of the development agenda in Central America. This region, together with the Caribbean, is highly vulnerable to the effects of climate change in Latin America. Climate change is manifesting itself through higher average temperatures and more frequent droughts that result in higher water stress, and through the rising frequency of extreme weather events such as tropical storms, hurricanes, floods and landslides, all of which pose significant challenges in the rural water supply and sanitation sector. The paper starts with a review of the historic data on temperature and precipitation trends in Central America and particularly at the regional level in Nicaragua. The data reveal a clear trend of the growing climate variability, increased water stress for crops, and greater frequency of extreme weather events. The rising intensity and frequency of ex-treme weather events is among the most critical risks to the region's development agenda, and they translate into high economic losses. This paper examines the impacts and implications of potential climate change on water resources in Nicaragua and makes key recommendations to integrate climate change and rural water supply and sanitation policies and programs in a way that increase resilience to current and future climate conditions. | 0

As plantas aquáticas são estudadas como um efeito do desequilíbrio causado pela poluição e/ou alagamento dos rios. A quantidade excessiva de plantas, conseqüente desse desequilíbrio, dificulta a navegação e a produção de energia elétrica. O objetivo deste trabalho foi identificar as principais plantas aquáticas do rio Tietê e relacioná-las com a turbidez da água dos diferentes reservatórios. Foram avaliados todos os focos de vegetação aquática emersa, flutuante e submersa, presentes em cada reservatório, em toda a sua extensão, sendo consideradas como importantes as espécies que apresentaram o caráter dominante. Foi observado que os represamentos apresentam problema de plantas aquáticas e a qualidade da infestação varia entre os reservatórios. Foram consideradas como dominantes as seguintes espécies: Brachiaria mutica, Brachiaria subquadripara, Eichhornia crassipes, Egeria densa, Egeria najas, Enidra sessilis e Typha angustifolia. Observou-se que houve uma tendência de maior ocorrência de plantas flutuantes e emersas (marginais) nos reservatórios com maior turbidez e de plantas submersas naqueles com menor turbidez. Para as duas braquiárias, observou-se que a freqüência das espécies aumentou com o aumento da turbidez até o limite de 34,93 NTU. O aguapé ocorreu com altos índices de freqüência (acima de 50%) em todos os reservatórios do rio Tietê, independentemente das características da água. Em se tratando das egérias, a freqüência das espécies aumentou gradativamente com a redução da turbidez e a taboa não apresentou uma relação com o índice estudado. A espécie E. sessilis se mostrou bastante dependente da qualidade da água, tendo sua freqüência aumentada com o aumento da turbidez. | Aquatic plants are studied as an effect of pollution unbalance and/or river flooding. The excessive amount of plants,as a consequence of such unbalance, hinders navigation and electric power production. The objective of this work was to identify the main aquatic plants of the Tietê River and to relate them with water turbidity of the different reservoirs. All the foci of aquatic immersed, floating and submerged vegetation in each reservoir were evaluated in all their extension. Those species presenting a dominant character were considered important.The reservoirs were found to present aquatic plant problems with the quality of infestation varying among the reservoirs. The following species were considered to be dominant: Brachiaria mutica, Brachiaria subquadripara, Eichhornia crassipes, Egeria densa, Egeria najas, Typha angustifolia and Enidra sessilis.There was a tendency for a greater occurrence of floating and submerged (marginal) plants in the reservoirs with greater turbidity and for a larger occurrence of submerged plants in reservoirs with less turbidity. For the two Brachiarias it was observed that the frequency of the species increased with the increase of turbidity up to the limit of 34.93 NTU. E. crassipes occurred with high frequency indexes (above 50%) in all the Tietê River reservoirs, independent of the characteristic of the water. For Egerias, frequency increased gradually with reduced turbidity and T. angustifolia did not present a relationship with the studied index. The species E. sessilis was found to be rather dependent on the quality of the water,its frequency increasing with increased turbidity.

Resumen: En las regiones kársticas de México la construcción de ciudades se ha realizado con el uso de materiales y procesos que no corresponden con el funcionamiento de la dinámica de filtración del agua. Con el uso de modelos hidrodinámicos se analizó la implementación del Diseño Urbano Sensible al Agua (DUSA) en el karst y se evaluó el beneficio económico al disminuir las inundaciones en Bacalar, Quintana Roo, México. Como primera etapa se modeló la precipitación, escorrentía e infiltración; se determinó la infraestructura útil para mantener la conectividad del sistema hidrológico y se generaron escenarios modelo de permeabilidad. En la segunda etapa se analizó la eficiencia de los escenarios modelo. Finalmente se valorizaron los daños de inundación para cada escenario. Los resultados muestran que, si se mantiene un 68% de área urbana permeable y 32% impermeable con infraestructuras esponja, con periodo de retorno de 10 años, se retrasa hasta por 30 minutos el inicio de las inundaciones. Esto implica un ahorro de 5.56 millones de salarios mínimos. La implementación de DUSA reduce inundaciones, genera ahorros sociales y económicos, pero además mantiene la dinámica de flujo y conectividad del karst. El modelo internacional de DUSA disminuye la vulnerabilidad de los sistemas kársticos ante el cambio climático. | Abstract: In the karst regions of Mexico, the construction of cities has been carried out using materials and processes that do not correspond to the functioning of filtration dynamics. The present work analyzes the effects of WSUD (Water Sensitive Urban Design) implementation on karst zone and the influence in the reduction of flooding. A permeability model was developed for the urban area of Bacalar, Quintana Roo, Mexico. As a first phase, precipitation, runoff, and infiltration were modeled; the useful infrastructure to maintain the connectivity of the hydrological system was determined and permeability models considering different scenarios were generated. In the second phase, the efficiency of the model scenarios was analyzed. Finally, flood damages were assessed for each scenario. The results show that if 68% of the urban area is kept permeable and 32% impermeable with sponge infrastructure, with a return period of 10 years, the onset of flooding is delayed by up to 30 minutes. This implies a saving of 5.56 million minimum wages. The implementation of DUSA reduces flooding, generates social and economic savings, but also maintains the flow dynamics and connectivity of the karst. The international DUSA model reduces the vulnerability of karst systems to climate change.

Este trabalho foi conduzido no Laboratório de Análise de Sementes da Faculdade de Ciências Agrárias da Universidade Oeste Paulista (UNOESTE), Presidente Prudente - SP, com o objetivo de avaliar os efeitos causados pelo alagamento na germinação e no vigor de sementes de feijão. As sementes foram submetidas aos tratamentos de alagamento por períodos de 0, 8, 16, 24, 32, 40 e 48 horas a 25ºC. Durante os tratamentos foram realizadas as avaliações de grau de umidade inicial e final, e após os mesmos, teste de germinação e avaliação do comprimento de hipocótilo e de raiz, peso seco da parte aérea e raiz. Os resultados mostraram que a germinação e o vigor das sementes decresceram com o alagamento, havendo decréscimo médio de 55 pontos percentuais na germinação, com 8 horas de alagamento. Ocorreu diferenciação de lotes através da germinação com sementes que passaram por períodos de alagamento iguais ou superiores a 8 horas. O número de sementes mortas e a inibição ao desenvolvimento de raiz e hipocótilo foram crescentes com o aumento do período de submersão. Desta forma, concluiu-se que o alagamento, por 8 horas, pode causar prejuízos irreversíveis ao estabelecimento da cultura do feijoeiro, bem como, se empregado em laboratório, pode ser um bom indicativo para diferenciação de níveis de qualidade fisiológica em sementes de feijão. | This work study was carried out to evaluate the effects of different flooding periods during germination and in the bean seeds vigor at UNOESTE Seed Analysis Laboratory. Seeds were submitted to flooding periods of 0, 8, 16, 24, 32, 40 and 48h at 25ºC. Moisture content was taken before and after flooding periods. The germination test and physiological parameters, such as hypocotyl and root length and their dry weights, were obtained after periods of flooding. Results showed that germination and vigor decreased subsequently to flooding, germination decreased 55 percentage points after 8h of seed submersion. There were differentiation differences between among seed lots in germination tests after flooding periods equal to, or higher than 8h. Dead seed number and inhibition in hypocotyl and root development, shown in this work study, increased with the submersion time. In conclusion, eight hours of flooding cause irreversible damage to bean culture establishment, and the same periods of submersion, in the laboratory, could be a very good indicative to differentiate seed physiological quality.