No abstract

São apresentados os resultados de pesquisa que quantificaram a precipitação efetiva e a interceptação das chuvas pelo dossel da floresta secundária de Mata Atlântica na "microbacia experimental B", do Laboratório de Hidrologia Florestal Walter Emmerich, em Cunha-SP. No período de um ano foram medidos a precipitação no aberto, a precipitação interna e o escoamento pelo tronco das árvores, totalizando 54 coletas. Um pluviômetro em área aberta e 16 no interior da floresta foram utilizados para quantificação dos dois primeiros processos, respectivamente. Para determinação do escoamento pelo tronco foram instalados dispositivos de espuma de poliuretano em 38 árvores. A água interceptada foi estimada pela diferença entre a precipitação no aberto e a precipitação efetiva. Concluiu-se que, em média, 18,6% da precipitação foi interceptada pela floresta, retornando à atmosfera na forma de vapor. Um montante de 81,2% alcançou o piso como precipitação interna e apenas 0,2% como escoamento pelo tronco. Os fluxos de precipitação interna e escoamento pelo tronco foram maiores no período caracterizado como chuvoso. Os porcentuais de interceptação foram superiores no período pouco chuvoso.

Stream water quality is controlled by the interaction of natural and anthropogenic factors over a range of temporal and spatial scales. Among these anthropogenic factors, land cover changes at catchment scale can affect stream water quality. This work aims to evaluate the influence of land use and seasonality on stream water quality in a representative tropical headwater catchment named as Córrego Água Limpa (Sao Paulo, Brasil), which is highly influenced by intensive agricultural activities and urban areas. Two systematic sampling approach campaigns were implemented with six sampling points along the stream of the headwater catchment to evaluate water quality during the rainy and dry seasons. Three replicates were collected at each sampling point in 2011. Electrical conductivity, nitrates, nitrites, sodium superoxide, Chemical Oxygen Demand (DQO), colour, turbidity, suspended solids, soluble solids and total solids were measured. Water quality parameters differed among sampling points, being lower at the headwater sampling point (0m above sea level), and then progressively higher until the last downstream sampling point (2500m above sea level). For the dry season, the mean discharge was 39.5ls (from April to September) whereas 113.0ls were averaged during the rainy season (from October to March). In addition, significant temporal and spatial differences were observed (P<0.05) for the fourteen parameters during the rainy and dry period. The study enhance significant relationships among land use and water quality and its temporal effect, showing seasonal differences between the land use and water quality connection, highlighting the importance of multiple spatial and temporal scales for understanding the impacts of human activities on catchment ecosystem services.

Abstract

Due to the importance of the species Araucaria angustifolia (Bertol.) Kuntze and on account of its presence in the "Núcleo Cunha", it was decided to study its influence on the process of rainfall redistribution. Daily throughfall (Tr) and stemflow of trees (Et) in a plot of 600 m 2 , equipped with 15 rain gauges and devices for collecting stemflow water on 19 trees were measured. A rain gauge installed in the open area located near the plot provided the rainfall data in the open (Pa). The interception (I) was estimated by the equation: I = Pa -(Et + Tr). The experimental period covered from October 2008 to March 2009. Sixty-eight rain events were recorded, resulting in 1,565.9 mm of precipitation in the open, and 163.4 mm were intercepted by the canopy. The gross precipitation is directly proportional to the rainfall in the open, since the intercept tends to decrease with the increase of rainfall classes. Negative interception events were recorded, showing another water entrance in the system. Palavras-chave:Araucaria angustifolia (Bertol.) Kuntze, gross precipitation, interception, throughfall, stemflow, precipitação efetiva, interceptação, transprecipitação, escoamento pelo tronco. 117 4 3 artigo anterior 9 Anais II Seminário de Recursos Hídricos da Bacia Hidrográfica do Paraíba do Sul: Recuperação de Áreas Degradadas Serviços

Atividades humanas demandam certos níveis de qualidade da água, no entanto, seus subprodutos a afetam por poluição. Este trabalho objetivou entender a poluição de bacias tributárias por meio da análise de parâmetros de qualidade da água e sua correlação com o uso e a ocupação do solo em microbacias do reservatório Billings na Região Metropolitana de São Paulo (RMSP). Utilizaram-se os parâmetros: Temperatura da água, Turbidez, pH, Oxigênio Dissolvido, Sólidos Totais Dissolvidos, Condutividade Elétrica e Fósforo Total. Os valores foram comparados com a Resolução CONAMA 357/2005. Foi proposto um agrupamento das classes de uso do solo conforme o grau de antropização, por meio de Sistema de Informação Geográfica (SIG). Os resultados mostraram correlações significativas entre os parâmetros de qualidade e o uso e a ocupação do solo. Locais mais antropizados foram responsáveis por uma maior degradação da qualidade da água para os parâmetros: Turbidez, Sólidos Totais Dissolvidos, Condutividade Elétrica e Fósforo Total. Alguns valores para as zonas de influência antrópica apresentaram desacordo com os parâmetros estabelecidos pela resolução CONAMA 357/2005. O estudo demonstrou a importância da preservação da vegetação em áreas de mananciais a fim de contribuir com a qualidade das águas.

Given the intrinsic hydrological cycle made of large input of water vapour and intense precipitation producing large volumes of water and sediment, modelling runoff and water losses in humid tropical watersheds is important for forest and water resources management. For instance, reliable simulations of the water cycle in such environments are a prerequisite for predictions of water quality, soil erosion and the climate change effects on water resources. The distributed parameter, physically based, continuous simulation, daily time step AnnAGNPS model, was implemented in almost completely forested (98% of its area, 0.56 km) Cunha watershed (Brazil) to assess its capability to simulate hydrological processes under tropical conditions. The simulated surface runoff was compared to 4-year observations with statistical indices on several time scales. The model, running with default CN of forest, showed poor predictions of runoff. After increasing CN from 63 to 72 by calibration, the runoff prediction capability of AnnAGNPS was satisfactory on annual, seasonal and monthly scales, while daily runoff predictions were less accurate. Modelling water losses at event scale showed that the effect of forest vegetation on water retention during a single precipitation was more limited than for longer periods (months, seasons and years), since evapo-transpiration and interception account for small shares (>20%) of total precipitation. This study demonstrated that the AnnAGNPS model has reliable runoff prediction capacity in tropical forest watersheds at the annual and seasonal scales (E > 0.73), whereas daily runoff simulations are less accurate (E = 0.44). The use of this model may prove an important tool for water resource and territory management in tropical rainforests.

Tropical montane cloud forests (TMCF) have paramount importance with regards to hydrological and ecological functions. Despite such importance in terms of water provision, they are one of the most endangered ecosystems on the planet. One important topic that is still unclear is related to TMCF regeneration: can it recover the hydrological function of such critical ecosystems? In the present paper, the hydrological effects of the natural regeneration of TMCF were examined. We selected three catchments with different degrees of TMCF, and we examined the relationship between the amount of TMCF over time and hydrological variables such as water yields and baseflow using a time series (1984–2011). Our results suggest that the increase in TMCF cover can contribute to increases in water yield. This pattern was found in a catchment with an increase of approximately 20% of forest cover. In catchments with TMCF increase lower than this threshold, water yield and flow path were influenced by hydroclimatic variables such as air temperature and rainfall. The effect of the reduction in water yield, in accordance with the increase in mean temperature, sheds light on possible consequences of climate change on ecosystem services produced in foggy environments. In light of these findings, aiming to increase the water yield, we recommend that regions frequently affected by fog are prioritized for forest restoration or conservation. To ensure significant effects, regeneration and/or successional development of TMCF has to reach at least 20% of a catchment area.