Fluxos hidrogeoquímicos em águas fluviais de microbacias do nordeste paraense e a sua relação com o uso da terra

O Nordeste Paraense é caracterizado por conter as mais antigas áreas de colonização da Amazônia, onde predomina a agricultura familiar itinerante de derruba e queima e também a pecuária bovina extensiva. A paisagem é fortemente marcada pela vegetação secundária em diversos estágios de sucessão e poucos remanescentes de floresta primária, a qual é geralmente localizada às margens de pequenos rios e igarapés. Nesse contexto, o presente estudo, conduzido em 14 microbacias no Nordeste Paraense sob diferentes usos e cobertura da terra e em quatro microbacias em áreas florestais sob baixo impacto antrópico, objetivou avaliar a hidrogeoquímica das águas fluviais para o embasamento da gestão de duas mesobacias hidrográficas nessa região. Foi detectado que a composição química das águas fluviais dos pequenos igarapés está sendo influenciada pelas práticas agrícolas adotadas em suas bacias de drenagem. Sinais hidrogeoquímicos diferenciados foram observados no caso das microbacias com presença de: sistema agrícola de derruba e queima; lavouras com irrigação e uso de agroquímicos; e pecuária bovina. Além disso, constatou-se a importância das microbacias florestadas para o aporte de nitrato, cloreto e sódio para os ecossistemas fluviais estudados. Adicionalmente verificou-se certa variação sazonal na hidrogeoquímica das águas fluviais e uma forte influência dos sistemas agropecuários, especialmente as pastagens, sobre os parâmetros físico-químicos mensurados, com redução da concentração de oxigênio dissolvido, e aumento da temperatura, do pH e da condutividade elétrica. Pelo presente estudo, pode-se inferir que a presença de mata ciliar é imprescindível para minimizar os impactos dos sistemas agrícolas nos recursos hídricos e deve ser apontada como uma ferramenta na gestão de bacias, assim como é recomendável a substituição de técnicas tradicionais que utilizam o fogo, por técnicas mais sustentáveis de produção agropecuária, como o plantio direto na capoeira. Por fim, sugere-se que dentre os parâmetros analisados, alguns podem ser recomendados, dependendo do uso da terra a ser focado, como indicadores de sustentabilidade ambiental dos sistemas agropecuários de produção para a gestão local de bacias hidrográficas.

Simulação de produção de sedimentos em microbacias em função de cenários de restauração florestal

In São Paulo state, deforestation and agriculture activities are increasing soil losses processes, especially in areas of susceptible soils where properties not adopt soil conservation practices. Environmental adequacy at property level regarding Permanent Protection Areas and Legal Reserves is considered a factor on reducing soil losses and considering that we assessed soil losses of different scenario of environmental adequacy. Simulations of erosive process were carried out in 15 catchments of Corumbataí river basin, according to different forest restoration scenarios, as well as the current situation of land use/land cover. The scenarios include the implementation of Permanent Preservation Areas (PPA), the reforestation of variable source areas, and two scenarios, the Legal Reserve installation in 20% of each catchment, being one of them for most critical areas in terms of erosion and the other at random. It was observed that the establishment of PPA and the reforestation of hydrologically sensitive areas, offered only a small contribution to the control of the erosive process, resulting in a reduction of 10% and 7,8%, respectively, while the legal reserve in critical areas has a significant reduction of 69,8%. The random scenario, in turn, resulted in a reduction of only 21,4%. Results show that reforestation could reduce soil losses, but previous studies of land prioritization and planning could increase significantly its efficiency at this process.

Procedimentos para o dimensionamento de reservatório de água pluvial para residências unifamiliares: viabilidade e aprimoramento metodológico

This paper focus to apply, to discuss and to propose the Maximum Harvesting Method improvement, regarding the method application, for household rainwater harvesting systems. For this purpose, the rainwater was considered to supply the flush toilet demand in a household for 3, 4, and 5 inhabitants. The 80, 120 and 200m2 catchments areas and the 0, 1, 2 and 4mm first flushes discharges were also considered. Further, the improvement suggestions for cistern volume calculus and volume/level dynamics variation in a period were presented and the results were compared applying the Simulation Analyses Method. The results indicate that the Maximum Harvesting Method could be applied and that the improvement proposal can be used to determinate the cistern volume as well to analyze the dynamic behavior of volume/level, constituting by itself a single tool to assist rainwater harvesting systems designers.

Hidrogeoquímica e qualidade das águas superficiais na Bacia do Alto Jacaré-Pepira (SP)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Validazione in torrenti appenninici monitorati di un modello fisicamente basato per la stima del deflusso solido sospeso

Il modello afflussi-deflussi e di erosione Kineros2, fisicamente basato, distribuito e a scala di evento, è stato applicato a due bacini idrografici montani della provincia di Bologna (Italia) al fine di testare e valutare il suo funzionamento in ambiente appenninico. Dopo la parametrizzazione dei due bacini, Kineros2 è stato calibrato e validato utilizzando dati sperimentali di portata e di concentrazione dei solidi sospesi, collezionati alla chiusura dei bacini grazie alla presenza di due stazioni di monitoraggio idrotorbidimetrico. La modellazione ha consentito di valutare la capacità del modello di riprodurre correttamente le dinamiche idrologiche osservate, nonchè di trarre conclusioni sulle sue potenzialità e limitazioni.

Dimensionamento di invasi per il controllo dei deflussi nei bacini urbanizzati

Urbanization is a continuing phenomenon in all the world. Grasslands, forests, etc. are being continually changed to residential, commercial and industrial complexes, roads and streets, and so on. One of the side effects of urbanization with which engineers and planners must deal with, is the increase of peak flows and volumes of runoff from rainfall events. As a result, the urban drainage and flood control systems must be designed to accommodate the peak flows from a variety of storms that may occur. Usually the peak flow, after development, is required not to exceed what would have occurred from the same storm under conditions existing prior to development. In order to do this it is necessary to design detention storage to hold back runoff and to release it downstream at controlled rates. In the first part of the work have been developed various simplified formulations that can be adopted for the design of stormwater detention facilities. In order to obtain a simplified hydrograph were adopted two approaches: the kinematic routing technique and the linear reservoir schematization. For the two approaches have been also obtained other two formulations depending if the IDF (intensity-duration-frequency) curve is described with two or three parameters. Other formulations have been developed taking into account if the outlet have a constant discharge or it depends on the water level in the pond. All these formulations can be easily applied when are known the characteristics of the drainage system and maximum discharge that these is in the outlet and has been defined a Return Period which characterize the IDF curve. In this way the volume of the detention pond can be calculated. In the second part of the work have been analyzed the design of detention ponds adopting continuous simulation models. The drainage systems adopted for the simulations, performed with SWMM5, are fictitious systems characterized by different sizes, and different shapes of the catchments and with a rainfall historical time series of 16 years recorded in Bologna. This approach suffers from the fact that continuous record of rainfall is often not available and when it is, the cost of such modelling can be very expensive, and that the majority of design practitioners are not prepared to use continuous long term modelling in the design of stormwater detention facilities. In the third part of the work have been analyzed statistical and stochastic methodologies in order to define the volume of the detention pond. In particular have been adopted the results of the long term simulation, performed with SWMM, to obtain the data to apply statistic and stochastic formulation. All these methodologies have been compared and correction coefficient have been proposed on the basis of the statistic and stochastic form. In this way engineers which have to design a detention pond can apply a simplified procedure appropriately corrected with the proposed coefficient.

Prozessorientierte Modellierung des Wassertransports zur Bewertung von Hochwasserschutzmaßnahmen in bewaldeten Entstehungsgebieten

Im der vorliegenden Arbeit wurden die Einflüsse verschiedener wasserwirtschaftlicher und forstwirtschaftlicher Maßnahmen auf das Abflussverhalten von bewaldeten Gebieten untersucht. Der Schwerpunkt lag auf der Erfassung der Veränderungen im natürlichen System durch die jeweilige Maßnahme. Der Wassertransport wurde dabei auf der Prozessebene im Hangmaßstab betrachtet. Wichtige Erkenntnisse hinsichtlich der Hochwasserentstehung in bewaldeten Gebieten wurden gewonnen. Daraus abgeleitet wurde eine Bewertung sowohl der natürlich gegebenen Systemgrößen als auch der einzelnen Maßnahmen bezüglich einer Hochwasservorsorge in Wäldern.Berücksichtigt wurden Änderungen in der Bestockung und in der Feinerschließung der bewaldeten Flächen durch Wege und Wirtschaftstrecken. Die Wassertransportprozesse wurden im Gelände untersucht und in Abhängigkeit der globalen klimatischen Randbedingungen sowie den bodenhydraulischen und landnutzungsspezifischen Parameter mit dem Niederschlag-Abfluss-Modell CATFLOW simuliert.Die Abflussdynamik wird im untersuchten Maßstab im wesentlichen durch die gegebene Bodenhydraulik, die Vorfeuchte des Bodens bei einem Niederschlag und durch die Niederschlagsintensität bestimmt. Die vergleichende Untersuchung von zwei rheinland-pfälzischen Waldstandorten ergab, dass im Bereich Soonwald ein relativ hohes Hochwasserrisiko besteht. Hier wirken sich Eingriffe durch forstwirtschaftliche Bewirtschaftungsmaßnahmen stark aus. Im Bereich des Pfälzerwaldes ist nur ein sehr geringes Hochwasserrisiko gegeben, da hier die natürlichen Gebietseigenschaften die Eingriffe durch Bewirtschaftungsmaßnahmen überprägen.

Studio dei metodi di valutazione della pericolosità associata ai "debris flow" in ambiente alpino

The present work concerns with the study of debris flows and, in particular, with the related hazard in the Alpine Environment. During the last years several methodologies have been developed to evaluate hazard associated to such a complex phenomenon, whose velocity, impacting force and inappropriate temporal prediction are responsible of the related high hazard level. This research focuses its attention on the depositional phase of debris flows through the application of a numerical model (DFlowz), and on hazard evaluation related to watersheds morphometric, morphological and geological characterization. The main aims are to test the validity of DFlowz simulations and assess sources of errors in order to understand how the empirical uncertainties influence the predictions; on the other side the research concerns with the possibility of performing hazard analysis starting from the identification of susceptible debris flow catchments and definition of their activity level. 25 well documented debris flow events have been back analyzed with the model DFlowz (Berti and Simoni, 2007): derived form the implementation of the empirical relations between event volume and planimetric and cross section inundated areas, the code allows to delineate areas affected by an event by taking into account information about volume, preferential flow path and digital elevation model (DEM) of fan area. The analysis uses an objective methodology for evaluating the accuracy of the prediction and involve the calibration of the model based on factors describing the uncertainty associated to the semi empirical relationships. The general assumptions on which the model is based have been verified although the predictive capabilities are influenced by the uncertainties of the empirical scaling relationships, which have to be necessarily taken into account and depend mostly on errors concerning deposited volume estimation. In addition, in order to test prediction capabilities of physical-based models, some events have been simulated through the use of RAMMS (RApid Mass MovementS). The model, which has been developed by the Swiss Federal Institute for Forest, Snow and Landscape Research (WSL) in Birmensdorf and the Swiss Federal Institute for Snow and Avalanche Research (SLF) takes into account a one-phase approach based on Voellmy rheology (Voellmy, 1955; Salm et al., 1990). The input file combines the total volume of the debris flow located in a release area with a mean depth. The model predicts the affected area, the maximum depth and the flow velocity in each cell of the input DTM. Relatively to hazard analysis related to watersheds characterization, the database collected by the Alto Adige Province represents an opportunity to examine debris-flow sediment dynamics at the regional scale and analyze lithologic controls. With the aim of advancing current understandings about debris flow, this study focuses on 82 events in order to characterize the topographic conditions associated with their initiation , transportation and deposition, seasonal patterns of occurrence and examine the role played by bedrock geology on sediment transfer.

Variabilità spaziale dei parametri di modelli afflussi-deflussi

L’invarianza spaziale dei parametri di un modello afflussi-deflussi può rivelarsi una soluzione pratica e valida nel caso si voglia stimare la disponibilità di risorsa idrica di un’area. La simulazione idrologica è infatti uno strumento molto adottato ma presenta alcune criticità legate soprattutto alla necessità di calibrare i parametri del modello. Se si opta per l’applicazione di modelli spazialmente distribuiti, utili perché in grado di rendere conto della variabilità spaziale dei fenomeni che concorrono alla formazione di deflusso, il problema è solitamente legato all’alto numero di parametri in gioco. Assumendo che alcuni di questi siano omogenei nello spazio, dunque presentino lo stesso valore sui diversi bacini, è possibile ridurre il numero complessivo dei parametri che necessitano della calibrazione. Si verifica su base statistica questa assunzione, ricorrendo alla stima dell’incertezza parametrica valutata per mezzo di un algoritmo MCMC. Si nota che le distribuzioni dei parametri risultano in diversa misura compatibili sui bacini considerati. Quando poi l’obiettivo è la stima della disponibilità di risorsa idrica di bacini non strumentati, l’ipotesi di invarianza dei parametri assume ancora più importanza; solitamente infatti si affronta questo problema ricorrendo a lunghe analisi di regionalizzazione dei parametri. In questa sede invece si propone una procedura di cross-calibrazione che viene realizzata adottando le informazioni provenienti dai bacini strumentati più simili al sito di interesse. Si vuole raggiungere cioè un giusto compromesso tra lo svantaggio derivante dall’assumere i parametri del modello costanti sui bacini strumentati e il beneficio legato all’introduzione, passo dopo passo, di nuove e importanti informazioni derivanti dai bacini strumentati coinvolti nell’analisi. I risultati dimostrano l’utilità della metodologia proposta; si vede infatti che, in fase di validazione sul bacino considerato non strumentato, è possibile raggiungere un buona concordanza tra le serie di portata simulate e osservate.

External drivers of biogeochemical cycles in a tropical montane forest in Ecuador

Successful conservation of tropical montane forest, one of the most threatened ecosystems on earth, requires detailed knowledge of its biogeochemistry. Of particular interest is the response of the biogeochemical element cycles to external influences such as element deposition or climate change. Therefore the overall objective of my study was to contribute to improved understanding of role and functioning of the Andean tropical montane forest. In detail, my objectives were to determine (1) the role of long-range transported aerosols and their transport mechanisms, and (2) the role of short-term extreme climatic events for the element budget of Andean tropical forest. In a whole-catchment approach including three 8-13 ha microcatchments under tropical montane forest on the east-exposed slope of the eastern cordillera in the south Ecuadorian Andes at 1850-2200 m above sea level I monitored at least in weekly resolution the concentrations and fluxes of Ca, Mg, Na, K, NO3-N, NH4-N, DON, P, S, TOC, Mn, and Al in bulk deposition, throughfall, litter leachate, soil solution at the 0.15 and 0.3 m depths, and runoff between May 1998 and April 2003. I also used meteorological data from my study area collected by cooperating researchers and the Brazilian meteorological service (INPE), as well as remote sensing products of the North American and European space agencies NASA and ESA. My results show that (1) there was a strong interannual variation in deposition of Ca [4.4-29 kg ha-1 a-1], Mg [1.6-12], and K [9.8-30]) between 1998 and 2003. High deposition changed the Ca and Mg budgets of the catchments from loss to retention, suggesting that the additionally available Ca and Mg was used by the ecosystem. Increased base metal deposition was related to dust outbursts of the Sahara and an Amazonian precipitation pattern with trans-regional dry spells allowing for dust transport to the Andes. The increased base metal deposition coincided with a strong La Niña event in 1999/2000. There were also significantly elevated H+, N, and Mn depositions during the annual biomass burning period in the Amazon basin. Elevated H+ deposition during the biomass burning period caused elevated base metal loss from the canopy and the organic horizon and deteriorated already low base metal supply of the vegetation. Nitrogen was only retained during biomass burning but not during non-fire conditions when deposition was much smaller. Therefore biomass burning-related aerosol emissions in Amazonia seem large enough to substantially increase element deposition at the western rim of Amazonia. Particularly the related increase of acid deposition impoverishes already base-metal scarce ecosystems. As biomass burning is most intense during El Niño situations, a shortened ENSO cycle because of global warming likely enhances the acid deposition at my study forest. (2) Storm events causing near-surface water flow through C- and nutrient-rich topsoil during rainstorms were the major export pathway for C, N, Al, and Mn (contributing >50% to the total export of these elements). Near-surface flow also accounted for one third of total base metal export. This demonstrates that storm-event related near-surface flow markedly affects the cycling of many nutrients in steep tropical montane forests. Changes in the rainfall regime possibly associated with global climate change will therefore also change element export from the study forest. Element budgets of Andean tropical montane rain forest proved to be markedly affected by long-range transport of Saharan dust, biomass burning-related aerosols, or strong rainfalls during storm events. Thus, increased acid and nutrient deposition and the global climate change probably drive the tropical montane forest to another state with unknown consequences for its functions and biological diversity.

Mac protocols for linear wireless (sensor) networks

Wireless sensor networks (WSNs) consist of a large number of sensor nodes, characterized by low power constraint, limited transmission range and limited computational capabilities [1][2].The cost of these devices is constantly decreasing, making it possible to use a large number of sensor devices in a wide array of commercial, environmental, military, and healthcare fields. Some of these applications involve placing the sensors evenly spaced on a straight line for example in roads, bridges, tunnels, water catchments and water pipelines, city drainages, oil and gas pipelines etc., making a special class of these networks which we define as a Linear Wireless Network (LWN). In LWNs, data transmission happens hop by hop from the source to the destination, through a route composed of multiple relays. The peculiarity of the topology of LWNs, motivates the design of specialized protocols, taking advantage of the linearity of such networks, in order to increase reliability, communication efficiency, energy savings, network lifetime and to minimize the end-to-end delay [3]. In this thesis a novel contention based Medium Access Control (MAC) protocol called L-CSMA, specifically devised for LWNs is presented. The basic idea of L-CSMA is to assign different priorities to nodes based on their position along the line. The priority is assigned in terms of sensing duration, whereby nodes closer to the destination are assigned shorter sensing time compared to the rest of the nodes and hence higher priority. This mechanism speeds up the transmission of packets which are already in the path, making transmission flow more efficient. Using NS-3 simulator, the performance of L-CSMA in terms of packets success rate, that is, the percentage of packets that reach destination, and throughput are compared with that of IEEE 802.15.4 MAC protocol, de-facto standard for wireless sensor networks. In general, L-CSMA outperforms the IEEE 802.15.4 MAC protocol.

Long-term effects of watershed management on surface runoff and sediment loss in the Ethiopian Highlands

Data on rainfall, runoff and sediment loss from different land use types have been collected by the Soil Conservation Research Programme in seven small catchments (73-673 hectares) throughout the Ethiopian Highlands since the early 1980s. Monitoring was carried out on a storm-to-storm basis for extended periods of 10-20 years, and the data are analysed here to assess long-term effects of changes. Soil and water conservation technologies were introduced in the early years in the catchments in view of their capacity to reduce runoff and sediment yield. Results indicate that rainfall did not substantially change over the observation periods. Land use changes and land degradation, however, altered runoff, as shown by the data from small test plots (30 m2), which were not altered by conservation measures during the monitoring periods. Sediment delivery from the catchments may have decreased due to soil and water conservation, while runoff rates did not change significantly. Extrapolation of the results in the highlands, however, showed that expansion of cultivated and grazing land induced by population growth may have increased the overall surface runoff. Watershed management in the catchments, finally, had beneficial effects on ecosystem services by reducing soil erosion, restoring soil fertility, enhancing agricultural production, and maintaining overall runoff to the benefit of lowland areas and neighbouring countries.

Active processes, morphology, and dynamics of icy debris fans: Landform evolution along rapidly degrading escarpments in alpine regions undergoing recent deglaciation

In the past few decades the impacts of climate warming have been significant in alpine glaciated regions. Many valley glaciers formerly linked as distributary glaciers to high-level icecaps have decoupled at their icefalls, exposing major escarpments and generating a suite of dynamic landforrns dominated by mass wasting. Ice-dominated landforms, here termed icy debris fans, develop rapidly by ice avalanching, rockfall, and icy debris flow. Field-based reconnaissance studies at two alpine settings, the Wrangell Mountains of Alaska and the Southern Alps of New Zealand, provide a preliminary morphogenetic model of spatial and temporal evolution of icy debris fans in a range of alpine settings. The influence of these processes on landform evolution is largely unrecognized in the literature dealing with post-glacial landform adjustment known as the paraglacial. A better understanding of these dynamic processes will be increasingly important because of the extreme geohazards characterizing these areas. Our field studies show that after glacier decoupling, icy debris fans begin to form along the base of bedrock escarpments at the mouths of catchments and prograde over valley glaciers. The presence of a distinct catchment, apex, and fan morphology distinguishes these landforms from other landforms common in periglacial hillslope settings receiving abundant clastic debris and ice. Ice avalanching is the most abundant process involved in icy debris fan formation. Fans developed below weakly incised catchments are dominated by ice avalanching and are composed primarily of ice with minor lithic detritus. Typically, avalanches fall into the fan catchments where sediments transform into grainflows that flow onto the fans. Once on the fans, avalanche deposits ablate rapidly, flattening and concentrating lithic fragments at the surface. Icy debris fans may become thick enough to become glaciers with splay crevasse systems. Fans developed below larger, more complex catchments are composed of higher proportions of lithic detritus resulting from temporary storage of ice and lithic detritus deposits within the catchment. Episodic outbursts of meltwater from the icecap may mix with the stored sediments and mobilize icy debris flows (mixture of ice and lithic clasts) onto the fans. Our observations indicate that the entire evolutionary cycle of icy debris fans probably occurs during an early paraglacial interval (i.e., decades to 100 years). Observations comparing avalanche frequency, volume, and fan morphologic evolution at the Alaska site between 2006 and 2010 illustrate complex response between icy debris fans even within the same cirque - where one fan may be growing while others are downwasting because of differences in ice supply controlled by their respective catchments and icecap contributions. As ice supply from the icecap diminishes through time, icy debris fans rapidly downwaste and eventually evolve into talus cones that receive occasional but ephemeral ice avalanches.

Impacts of environmental change on water resources in the Mount Kenya Region

Water resources are becoming increasingly scarce in the Mt. Kenya region. Land use and climate change may pose additional challenges to water management in the future. In order to assess the impacts of environmental change, the NRM3 Streamflow Model, a simple, semi-distributed, grid-based water balance model, is evaluated as a tool for discharge prediction in six meso-scale catchments on the western slopes of Mt. Kenya, and used to analyse the impact of land use and climate change scenarios on water resources.

Surface uplift and climate change - the geomorphic evolution of the western escarpment of the Andes of northern Chile between the Miocene and present

The Western Escarpment of the Andes at 18.30°S (Arica area, northern Chile) is a classical example for a transient state in landscape evolution. This part of the Andes is characterized by the presence of >10,000 km2 plains that formed between the Miocene and the present, and >1500 m deeply incised valleys. Although processes in these valleys scale the rates of landscape evolution, determinations of ages of incision, and more importantly, interpretations of possible controls on valley formation have been controversial. This paper uses morphometric data and observations, stratigraphic information, and estimates of sediment yields for the time interval between ca. 7.5 Ma and present to illustrate that the formation of these valleys was driven by two probably unrelated components. The first component is a phase of base-level lowering with magnitudes of∼300–500 m in the Coastal Cordillera. This period of base-level change in the Arica area, that started at ca. 7.5 Ma according to stratigraphic data, caused the trunk streams to dissect headward into the plains. The headward erosion interpretation is based on the presence of well-defined knickzones in stream profiles and the decrease in valley widths from the coast toward these knickzones. The second component is a change in paleoclimate. This interpretation is based on (1) the increase in the size of the largest alluvial boulders (from dm to m scale) with distal sources during the last 7.5 m.y., and (2) the calculated increase in minimum fluvial incision rates of ∼0.2 mm/yr between ca. 7.5 Ma and 3 Ma to ∼0.3 mm/yr subsequently. These trends suggest an increase in effective water discharge for systems sourced in the Western Cordillera (distal source). During the same time, however, valleys with headwaters in the coastal region (local source) lack any evidence of fluvial incision. This implies that the Coastal Cordillera became hyperarid sometime after 7.5 Ma. Furthermore, between 7.5 Ma and present, the sediment yields have been consistently higher in the catchments with distal sources (∼15 m/m.y.) than in the headwaters of rivers with local sources (<7 m/m.y.). The positive correlation between sediment yields and the altitude of the headwaters (distal versus local sources) seems to reflect the effect of orographic precipitation on surface erosion. It appears that base-level change in the coastal region, in combination with an increase in the orographic effect of precipitation, has controlled the topographic evolution of the northern Chilean Andes.