On the possibility of using geothermal data for paleoclimate studies in Antarctica: the experience from Portugal

The study of the climate in the past and the climate change in mainland Portugal using geothermal data has started in 1996. Reconstruction of ground surface temperature (GST) history from temperature logs measured in a 200 m deep borehole located 5 km away from the town of Évora in Portugal, indicates a warming of 1K since the second half of the nineteenth century to the middle of the 90s of the twentieth century, increasing considerably in the last 10 years. Results of the reconstruction (based on a functional space inversion – FSI – method) are compared with air temperatures recorded at the Lisbon meteorological station since 1856. The air temperature time series display a warming trend with the amplitude about 1K for the same period. The coupling of the air and ground temperature changes and their downward propagation by heat conduction was confirmed by repeated logging in November 2003, 6.7 years after obtaining the first temperature log. The method can be used in paleoclimatic studies in Antarctica as well as in areas with permafrost

Update Heat Flow Density Map for Portugal

New thermal conductivity, heat production and temperature data obtained in Portugal were used to produce a new heat flow density map. Heat flow density values in Portugal vary between 42 and 115 mW/m2 and allow the extrapolation of temperatures to depths not yet reached by existing boreholes. Additionally, temperature maps at 500 and 1000 m depths and a two-dimensional model constructed along a north-south profile in the area where there is more geothermal information are given

Is debt replacing equity in regulated privatized infrastructure in developing countries?

The main purpose of this paper is to describe the evolution of the financing structure of regulated privatized utilities and transport companies. To do so, the authors rely on a sample of 121 utilities distributed over 16 countries, and 23 transport infrastructure operators and 23 transport services operators distributed over 23 countries. They show that leverage rates vary significantly across sectors, with the highest rates observed in transport and the lowest in water. Moreover, the authors also show that the 1997 Asia crisis led operators to adjust their financial structure differently in different regions. Overall, the evidence they present shows that debt is replacing equity in financing the investment needs of utilities and transport services in developing countries. These results raise some questions as to whether the regulator's mandate should be expanded to monitor the financial structure of companies and as to whether the international community should make a stronger commitment to more transparent regulatory accounting systems.International Terrorism&Counterterrorism,Banks&Banking Reform,Payment Systems&Infrastructure,Public Sector Economics&Finance,Municipal Financial Management,Banks&Banking Reform,Public Sector Economics&Finance,Rural Finance,Municipal Financial Management,Environmental Economics&Policies

Preliminary results of an ERT in a vineyard in Estremoz, Portugal

In 2014 a geophysical survey was carried out in a vineyard in Quinta do Mouro, in the wine region of Estremoz, in southern Portugal, to understand and study the geoelectrical characteristics of the soil. The main objective of the geophysical work was to delineate and characterize the soil and bedrock in geoelectrical terms in the vineyard’s area. The area has patches where high quality grapes are produced and patches which produce mediocre grapes. The geophysical survey aimed to try to understand if there was any correlation between the electrical resistivity of the ground (related with the amount of moisture in the ground) and the quality of the vines and grapes. The results indicate that, in this case, the quality of the vines and grapes appear to be related with the moisture in the ground, the good vines and grapes being associated with higher moisture content of the ground and so lower electrical resistivities

Results of geoelectrical surveys in the area of Crater 70, Deception Island, Maritime Antarctica

Deception Island is horse-shoe shaped stratovolcano with 15 km diameter and a large caldera that opens towards the southeast, forming a bay about 7 km wide. The maximum altitude is at Mount Pond (539 m a.s.l.). About 57% of the island area is covered by glaciers. In geological terms Deception Island is composed of volcano-sedimentary deposits, including pyroclastic flows and deposits, strombolian scoriae and lava, volcanic and hypo-volcanic indurated ashes, and phreatomagmatic deposits. Recent eruptions took place in the interior of the island in 1967, 1969, and 1970. Permafrost is widespread in the island but its characteristics are still poorly studied. In this study we present geoelectrical data collected in the Crater 70 area of Deception Island which was formed during the eruptions of 1970. The study area is located in the southern slope of a volcanic cone and the objective of the geoelectrical survey was to determine if there were any permafrost aggradation after the eruptive event and to assess the thickness of the frozen body. Two electrical resistivity tomography (ERT) profiles and a vertical electrical sounding (VES) were done (Fig. 1). Geoelectrical methods are particularly well adapted to study the spatial distribution of permafrost because of its high electrical resistivities in comparison with the electrical resistivities of soil and rocks with water and above 0 oC

Effect of the curing time on the numerical modelling of the behaviour of a chemically stabilised soft soil

The ability of the Modified Cam Clay (MCC) model combined with the Von Mises (VM) model, considering the effect of curing time on the enhancement of the mechanical properties of a chemically stabilised soft soil is examined. The evolution of the strength and stiffness over time is based on the results of undrained compressive strength (UCS) tests carried out for different curing times (from 28 days to 360 days). Initially, the MCC/VM models associated with the effect of curing time are validated by CIU triaxial tests, for curing times of 28 and 90 days. Finally, the behaviour of an embankment built on a soft soil reinforced with deep mixing columns is predicted based on the previously validated models. The results show that the increase of curing time of the DMCs slightly decreases the settlement obtained with a curing time of 28 days

Climate Change Impact in a Shallow Coastal Mediterranean Aquifer, at Saïdia, Morocco

A density dependent numerical flow model was applied to study the climate change impact in an unconfined shallow aquifer in the Mediterranean coast of Morocco. The stresses imposed to the model were derived from the IPCC emission scenarios and included recharge variations, rising sea level and advancing seashore. The simulations show that there will be a significant decline in the renewable freshwater resources and that salinity increases can be quite large but are limited to a restricted area

Heat Flow Density Estimations in the Portuguese Northern Hercynian Massif using Silica Geothermometry

Surface heat flow density (HFD) estimates in the Portuguese northern Hercynian Massif are difficult to obtain using the usual Fourier method. As a matter of fact, this zone is mostly composed by granitoid and metamorphic rocks, and most wells drilled there are too shallow for reliable HFD calculations; furthermore, HFD estimates are scarce and their geographical distribution is still very irregular. All these conditions imply that a HFD map for this region must be obtained using alternative methods, such as the silica geothermometry method. Under certain conditions, the use of silica geothermometers to estimate HFD in mineral waters has proved to be an effective way to understand and establish the thermal regime in areas with scarce conventional HFD determinations. Because temperatures obtained with silica geothermometry are related to deep thermal conditions in the crust and to water-rock equilibrium, a regional HFD analysis may be carried out using those temperatures. The silica geothermometer, developed by Truesdell in 1976 (Truesdell, 1976), give good results for low SiO2 concentrations, which is the case for the Portuguese northern Hercynian Massif, and is applied to more than 30 samples of mineral water occurrences reported for the zone. This number of samples, even though small, is considerably higher and more evenly distributed than conventional HFD estimates for the same area. Application of silica geothermometry to northern Hercynian Massif waters shows a discrete reservoir temperature zoning, ranging from about 45 ºC, in its southwest limit, to more than 120 ºC, towards its northeast limit. Using temperatures obtained by silica geothermometry and heat flow density values calculated through the conventional method in an area of 1º x 1º in the study zone, an empirical linear relationship between HFD and temperatures obtained by silica geothermometry is obtained and used to construct a HFD map for the Portuguese northern Hercynian Massif. The resulting HFD map is compared with the general geological and structural framework, and an attempt to a geothermal characterisation of the Portuguese northern Hercynian Massif is made