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- Effects of prescribed fire on surface soil in a Pinus pinaster plantation, northern PortugalPublication . Meira Castro, Ana C.; Shakesby, R. A.; Espinha Marques, J.; Doerr, S. H.; Meixedo, JP; Teixeira, J.; Chaminé, Helder I.In order to decrease the risk of severe wildfire, prescribed fire has recently been adopted in Portugal and elsewhere in the Mediterranean as a major tool for reducing the fuel load instead of manual or mechanical removal of vegetation. There has been some research into its impact on soils in shrublands and grasslands, but to date little research has been conducted in forested areas in the region. As a result, the impact of prescribed fire on the physico-chemical soil characteristics of forest soils has been assumed to be minimal, but this has not been demonstrated. In this study, we present the results of a monitoring campaign of a detailed pre- and post-prescribed fire assessment of soil properties in a long-unburnt P. pinaster plantation, NW Portugal. The soil characteristics examined were pH, total porosity, bulk density, moisture content, organic matter content and litter/ash quantity. The results show that there was no significant impact on the measured soil properties, the only effect being confined to minor changes in the upper 1 cm of soil. We conclude that provided the fire is carried out according to strict guidelines in P. pinaster forest, a minimal impact on soil properties can be expected.
- Insignificant impact of prescribed fire on surface soil in a Pinus pinaster plantation, northern PortugalPublication . Meira Castro, Ana C.; Shakesby, R.; Marques, J. Espinha; Santos, N.; Šmid, M.; Meixedo, João Paulo; Teixeira, J.; Chaminé, Helder I.; Doerr, S. H.Following a prescribed fire in a Pinus pinaster forest site located in the north-west Portugal, monitoring of any changes in selected soil characteristics and soil hydrology was undertaken to assess the effects of burning on the following: pH, electrical conductivity, water content, organic carbon and porosity. Thirty plots were established on a regular grid. At each sample plot before and after the fire, samples were collected (disturbed samples from depths of 0-1cm and 1-5cm; undisturbed core samples from 0-5cm). The results indicate that there was no measurable impact on the properties of the soil following this carefully conducted prescribed fire. The fire only affected the litter layer, as intended. Confirmation of this minimal impact on the soil was provided by regrowth of grasses and herbs already occurring two months after the fire. The implication is, therefore, that provided this wildfire-risk reduction strategy is carried out under existing strict guidelines, any impact on soil quality will be minimal.
- Assessment of groundwater contamination in an agricultural peri-urban area (NW Portugal): an integrated approachPublication . Barroso, M. Fátima; Ramalhosa, Maria João; Olhero, A.; Antão, M. C.; Pina, M. F.; Guimarães, L.; Teixeira, J.; Afonso, M. J.; Delerue-Matos, Cristina; Chaminé, Helder I.The excessive use of pesticides and fertilisers in agriculture has generated a decrease in groundwater and surface water quality in many regions of the EU, constituting a hazard for human health and the environment. Besides, on-site sewage disposal is an important source of groundwater contamination in urban and peri-urban areas. The assessment of groundwater vulnerability to contamination is an important tool to fulfil the demands of EU Directives. The purpose of this study is to assess the groundwater vulnerability to contamination related mainly to agricultural activities in a peri-urban area (Vila do Conde, NW Portugal). The hydrogeological framework is characterised mainly by fissured granitic basement and sedimentary cover. Water samples were collected and analysed for temperature, pH, electrical conductivity, chloride, phosphate, nitrate and nitrite. An evaluation of groundwater vulnerability to contamination was applied (GOD-S, Pesticide DRASTIC-Fm, SINTACS and SI) and the potential nitrate contamination risk was assessed, both on a hydrogeological GIS-based mapping. A principal component analysis was performed to characterised patterns of relationship among groundwater contamination, vulnerability, and the hydrogeological setting assessed. Levels of nitrate above legislation limits were detected in 75 % of the samples analysed. Alluvia units showed the highest nitrate concentrations and also the highest vulnerability and risk. Nitrate contamination is a serious problem affecting groundwater, particularly shallow aquifers, especially due to agriculture activities, livestock and cesspools. GIS-based cartography provided an accurate way to improve knowledge on water circulation models and global functioning of local aquifer systems. Finally, this study highlights the adequacy of an integrated approach, combining hydrogeochemical data, vulnerability assessments and multivariate analysis, to understand groundwater processes in peri-urban areas.
- Assessment of sustainability of groundwater in urban areas (Porto, NW Portugal): a GIS mapping approach to evaluate vulnerability, infiltration and rechargePublication . Freitas, Liliana; Afonso, Maria José; Pereira, Alcides J. S. C.; Delerue-Matos, Cristina; Chaminé, Helder I.The urban water cycle concept demonstrates the connectivity and interdependence of urban water resources and human activities, and the need for integrated sustainable management studies and approaches. The role of climate, geology, geo-morphology, land-use/cover, hydrogeochemistry, hydraulics, human activities among other features is significant in urban areas. In addition, land-use development has a stronger influence on terrestrial hydrology than climate variability. The need for provision of safe water, sanitation and drainage systems is key elements to consider for the groundwater resources in complex urban environments. In recent years, a new focus has emerged, addressing issues on integrated GIS mapping stud-ies on urban water supply systems, particularly in historical cities. To illustrate that approach the Porto urban area (NW Portugal) was selected. This work presents a comprehensive study to demonstrate the key importance of urban groundwater studies, as well as the evaluation of the Urban Infiltration Potential Index and the potential groundwater yields that might be available for non-potable uses, such as irrigation of parks and lawns, street cleaning and firefighting. This strategy is useful for the planning and management of urban groundwater abstraction in an equitable and sustainable manner.
- Characterization of soils in an area of prescribed firePublication . Santos, N.; Šmid, M.; Meira Castro, Ana C.; Marques, J. Espinha; Meixedo, João Paulo; Góis, Joaquim; Chaminé, Helder I.; Vivas, António; Carvalho, E.The prescribed fire is a technique that is often used, it has several advantages. Pedological and hydropedological techniques were tested to assess the prescribed fire changes may cause in soils. This work was performed in Tresminas area (Vila Pouca de Aguiar, Northern Portugal), during February and March 2011. In the present study we applied several techniques. For the field sampling was followed the ISO 10381-1[1], ISO 10381-2[2], and FAO rules [3], as well as were used a grid with 17 points for measuring the soil parameters. During the fire, we have tried to check, with the assistance of the Portuguese Forestry Authority, some important parameters such as, the propagation speed, the size of the flame front and the intensity of energy emitted per unit area. Before the fire, was collected carefully soil disturbed and undisturbed samples for laboratory analysis, and measured soil water content; we also have placed four sets of thermocouples for measuring soil temperature. After the fire, were collected the thermocouples and new soil samples; the water content were measured in the soil and collected ashes. In the laboratory, after preparing and sieving the samples, were determined the soil particle size. The soil pH and electrical conductivity in water was also determined. The total carbon (TC) and inorganic carbon (IC)[4] was measured by a Shimadzu TOC-Vcsn. The water content in soil has not varied significantly before and after the fire, as well as soil pH and soil electrical conductivity. The TC and IC did not change, which was expected, since the fire not overcome the 200° C. Through the various parameters, we determined that the prescribed fire didn’t affect the soil. The low temperature of the fire and its rapid implementation that lead to the possible adverse effects caused by the wild fire didn’t occurred.
- Geotechnical Hazards in Rocky Slopes (Northern Portugal): Focused on MethodologyPublication . Trigo, José Filinto; Pacheco, Carlos; Fernandes, João; Ferraz, Pedro; Sousa, Jorge; Machado, Rui; Duarte, Sara; Mendes, Ana; Freitas, Liliana; Teixeira, José; Ramos, Luís; Afonso, Maria José; Chaminé, Helder I.Interdisciplinary studies of rocky slopes stability have been performed on Northern Portugal, that allowed to establish a design methodology. This approach carries together the use of more traditional techniques, with the application of more recent technologies, such as unmanned aerial vehicles. This work presents a set of procedures that have been applied successfully in several case studies, describing the different stages, with an emphasis on the production of a ground three-dimensional model. This model is generated from photographs obtained with successive drone flights, with overlapping. It is the support for the development of subsequent stages, especially for the characterisation of the trajectories of rockfalls and modelling, the development of susceptibility mapping and of rock slope hazard. In this context, the Natural Slope Quality Index (N-SQI ), an adaptation of the Slope Quality Index (SQI), orientated to natural slopes, is presented. The Block Gravity Number (BGN), created in order to hierarchise rock blocks, selecting them for modelling, is also proposed.
- Hydrogeochemical, isotopical and ecotohicological approach to the Paranhos spring galleries catchworks from Porto urban area (nw Portugal)Publication . Guimarães, Laura; Afonso, Maria José; I. Chaminé, Helder; Marques, José M.; Carreira, Paula; Costa, Isilda; Teixeira, José; Guilhermino, Lúcia; Carvalho, José Martins; Fonseca, Paulo E.; Rocha. Fernando T.; Beleza, VitorinoThis multidisciplinary study presents the preliminary results of the hydrogeochemical, isotopical and ecotoxicological analyses performed to assess the nature and suitability for use of groundwater from the Paranhos’ spring galleries catchworks. These springs constituted for more than five centuries one of the main water supplies to Porto city. For the characterisation of the underground area (ca. 3km extension and a-25m of depth), constituted mainly by granitic rocks, the following tools were applied: i) subsurface geological and geotechnical mapping and; ii) hydrogeological, isotopical and ecotoxicological techniques. Surface and subsurface fieldwork surveys were first carried out to identify major tectonic accidents responsible for groundwater circulation paths and to assess lithological and structural heterogeneity. Hydrogeological fieldwork campaigns were then performed, and in situ determinations included: temperature (°C), pH and electrical conductivity (uS/cm). Several sampling sites were subsequently established, based on the surface activities located on the course of the springs, and water samples were collected for hydrogeochemical, isotopical and ecotoxicological analyses. All the water samples have been analysed for major element concentration. The isotopic techniques employed included d2H and d18O. For ecotoxicological evaluation standard acute bioassays with Daphnia magna were performed. For each sample, two 48h-LC5o bioassays were simultaneously performed: one with PH correction and the other without pH correction. In each bioassay, five concentrations of groundwater were prepared by dilution of the original sample with ASTM hard water. The hydrogeochemical analyses showed a nitrate and sulphate-enriched composition for these groundwaters, probably resulting from intense urbanisation, sewer leakage and some agricultural practices. Concerning the ecotoxicological analyses, no mortality was observed in any of the tests performed. The results obtained in this study suggest that part of Porto urban groundwater could be suitable for irrigation uses, but additional tests must be carried out to verify its compliance with existing standards of water quality. Specifically, geoenvironmental and ecotoxicological studies are required to assess potential variations in water composition and toxicity associated with seasonal changes in climate and human activities.
- A preliminary hydrogeologic conceptual model of the Manteigas-Nave de Santo Antonio-Torre sector (Serra da Estrela Natural park, central Portugal)Publication . Marques, Jorge Espinha; Marques, José M.; Carreira, Paula M.; I. Chaminé, Helder; Fonseca, Paulo E.; Samper, Javier; Pisani, B.; Alvares, D.; Vieira, Gonçalo T.; Mora, Carla; Teixeira, José; Gomes, Alberto; Carvalho, José Martins; Borges, Frederico S.; Rocha, Fernando T.; Beleza, VitorinoThis work is strongly connected with one of the most crucial water research issues at the turn of the millennium “High Mountain Areas Hydrology” (UNESCO IHP-VI Programme). Special emphasis is dedicated to high mountains and their role and impact on surface water/groundwater interaction at Serra da Estrela region - Central Portugal, in order propose a preliminary hydrogeologic conceptual model of the Manteigas - Nave de Santo Antonio - Torre sector, contributing to i) increase knowledge on recharge and discharge processes in this high mountain area and ii) assess the role of snowmelt as a source of groundwater resources, with the aid of coupled isotopic and geochemical techniques. The isotopic signatures of Caldas de Manteigas thermomineral waters combined with the i) morphostructural data and ii) isotopic composition of shallow groundwater and precipitation samples, made it possible to identify possible recharge areas, which should be located at altitude sites above 1500 m a.s.l.. The recharge altitudes are similar to those of Nave de Santo Antonio area which is directly located on the Braganca-Vilarica-Manteigas fault zone. This tectonic structure should play an important role in groundwater recharge and circulation towards the discharge zone at the Spas.
- From engineering geosciences mapping towards sustainable urban planningPublication . Chaminé, Helder I.; Teixeira, José; Freitas, Liliana; Pires, Ana; Silva, Rui S.; Pinho, Telma; Monteiro, Rosália; Costa, Ana Lúcia; Abreu, Tiago; Trigo, José Filinto; Afonso, Maria José; Carvalho, José MartinsMaps are of key topical importance in urban geoscience and engineering practice, mainly in field data synthesis and communication related to a number of fields, such as geomatic techniques, applied geology and geomorphology, engineering geology, soil and rock geotechnics, slope geotechnics, subsurface site geotechnical investigations, urban hydrology, hydraulics and sanitation, coastal zones management, urban geoarcheology and heritage, planning and land use. The value of preparing engineering geoscience maps and plans specificallyfor urban engineering purposes are still a challenging task, particularly to end-users and planners. Nowadays, the application of Geographic Information Systems to geosciences and engineering has become more common. This paper emphasises the importance of an accurate ground field survey and inventory at several scales, GIS mapping and databases, and integrated multidisciplinary urban studies as useful tools to support a sustainable land use planning. Some selected sites are highlighted to demonstrate the importance of urban mapping for land use planning. Thus, in this study the significance of a smart urban geoscience approach is stressed.
- Site appraisal in fractured rock media: coupling engineering geological mapping and geotechnical modellingPublication . Chaminé, Helder I.; Afonso, Maria José; Trigo, José Filinto; Freitas, Liliana; Ramos, Luís; Carvalho, José MartinsGeotechnical surveys are based on collecting data from fieldwork and are a key element of rock-mass quality assessment in rock engineering. The lessons learned in several engineering projects underline the value of the accuracy of the basic geological and geotechnical data information related to the rock masses description and evaluation. An evaluation based on engineering geosciences, hydraulic and geotechnical features of rock masses involves combining parameters to derive quantitative geomechanical classifications for engineering design. In the present work, two selected sites are highlighted to demonstrate the importance of GIS mapping and models. Mapping and quantifying the on-site measurements’ information content and building a geo-database is vital for decision-making processes and risk assessment on sustainable engineering design with nature and hazards.
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