Regimes of spatial ordering in Brazil: Neoliberalism,leftist populism and modernist aesthetics in slum upgrading in Recife

This paper shows how regimes of spatial ordering in Brazil are produced by the entangling of neoliberalism, leftist populism and modernist visions. The paper focuses on Prometrópole, a slum upgrading project in Recife funded by the World Bank, which commenced in 2007. In this project, the neoliberal dimension manifests in the idea that the state, private companies and citizens together are responsible for (re)constructing urban space, and further, that beneficiaries should behave as autonomous citizens, taking responsibility for their new living environment. The leftist political dimension is seen in participatory procedures to involve the target population from project design through to implementation, in expectation of their cooperation with the government. The modernist aesthetics – of straight lines, open spaces and visible order – informs the project design with the requirement to use the new houses and public spaces according to the standards of ‘modern civilization’. As our research shows, such a regime of spatial ordering clashes with the livelihoods of the urban poor, whose quality of life might even deteriorate as a result of the intervention. Furthermore, so‐called participatory procedures fail to grant the target population any real influence in creating their environment. Consequently, these residents of the new housing estate drastically reconstruct their private and public areas, reappropriating the urban space and contesting the regime of spatial ordering imposed upon them.     

Assessing the shear-sheltering theory applied to low-level jets in the nocturnal stable boundary layer

This paper investigates the existence of shear sheltering on turbulence data over a quasi-ideal experimental site in Oklahoma, USA. Originally developed for engineering flows, the shear-sheltering theory is predicated upon the idea of low-level jets blocking large eddies aloft, preventing them from propagating to the surface. In this scenario, suppression of low-frequency turbulence energy and reduction of surface fluxes would be expected. Results from the Oklahoma experiment show instead an enhancement of surface turbulence intensity and of the relative contribution of large scales to total (co)variances for low-level jet cases with strong shear, thus suggesting the absence of shear sheltering at the site. The results underline the complexity of surface-atmosphere interactions in nocturnal stable conditions. Atmospheric modeling of exchange using various scenarios of surface characteristics, flow regimes, and low-level jet properties is suggested to further assess the potential applicability of the shear-sheltering theory to atmospheric flows.     

An elastoplastic evaluation of the stress state around cylindrical openings based on a closed multiaxial yield surface

There are many applications encountered in geo‐engineering where there is a need to evaluate the stress state around circular openings. This paper presents a new analytical solution for evaluating the stresses around a cylindrical excavation in an elastoplastic medium defined by the closed MSDP_u yield surface. The proposed formulation takes into account the 3D stress geometry with a plasticity criterion that intersects the mean stress axis on the positive (compressive) and negative (tensile) sides. The results shown here illustrate how the stress distribution and yielding zone size are affected by various influence factors. Validation of the proposed formulation is made by comparing calculated results with existing analytical solutions and a numerical simulation. Copyright © 2008 John Wiley & Sons, Ltd.     

Reactive transport modelling of mine tailings columns with capillarity-induced high water saturation for preventing sulfide oxidation

A series of laboratory column tests on reactive mine tailings was numerically simulated to study the effect of high water saturation on preventing sulfide mineral oxidation and acid mine drainage (AMD). The approach, also known as an elevated water table (EWT), is a promising alternative to full water covers for the management and closure of sulfidic tailings impoundments and for the long term control of acid mine drainage. The instrumented columns contained reactive tailings from the Louvicourt mine, Quebec, and were overlain by a protective sand cover. Over a 13–19 month period, the columns were exposed to atmospheric O₂ and flushed approximately every month with demineralized water. A free draining control column with no sand cover was also used. During each cycle, water table elevations were controlled by fixing the pressure at the column base and drainage water was collected and analyzed for pH and Eh, major ions, and dissolved metals (Fe, Zn, Cu, Pb, and Mg). The columns were simulated using the multi-component reactive transport model MIN3P which solves the coupled nonlinear equations for transient water flow, O₂ diffusion, advective–dispersive transport and kinetic geochemical reactions. Physical properties and mineralogical compositions for the material layers were obtained from independent laboratory data. The simulated and observed data showed that as the water table elevation increased, the effluent pH became more neutral and SO₄ and dissolved metal concentrations decreased by factors on the order of 10²–10³. It is concluded that water table depths less than or equal to one-half of the air entry value (AEV) can keep mine tailings sufficiently saturated over the long term, thus reducing sulfide oxidation and AMD production.     

A modification to the Soil Conservation Service curve number method for steep slopes in the Loess Plateau of China

The Soil Conservation Service curve number (CN) method is widely used for predicting direct runoff from rainfall. However, despite the extent of cultivation on hillslope areas, very few attempts have been made to incorporate a slope factor into the CN method. The objectives of this study were (1) to evaluate existing approaches integrating slope in the CN method, and (2) to develop an equation incorporating a slope factor into the CN method for application in the steep slope areas of the Loess Plateau of China. The dataset consisted of 11 years of rainfall and runoff measurements from two experimental sites with slopes ranging from 14 to 140%. The results indicated that the standard CN method underestimated large runoff events and overestimated small events. For our experimental conditions, the optimized and non‐optimized forms of the slope‐modified CN method of the Erosion Productivity Impact Calculator model improved runoff prediction for steep slopes, but large runoff events were still underestimated and small ones overpredicted. Based on relationships between slope and the observed and theoretical CN values, an equation was developed that better predicted runoff depths with an R² of 0·822 and a linear regression slope of 0·807. This slope‐adjusted CN equation appears to be the most appropriate for runoff prediction in the steep areas of the Loess Plateau of China. Copyright © 2005 John Wiley & Sons, Ltd.     

Protracted river response to medieval earthquakes

Mountain rivers respond to strong earthquakes by rapidly aggrading to accommodate excess sediment delivered by co-seismic landslides. Detailed sediment budgets indicate that rivers need several years to decades to recover from seismic disturbances, depending on how recovery is defined. We examine three principal proxies of river recovery after earthquake-induced sediment pulses around Pokhara, Nepal's second largest city. Freshly exhumed cohorts of floodplain trees in growth position indicate rapid and pulsed sedimentation that formed a fan covering 150 km² in a Lesser Himalayan basin with tens of metres of debris between the 11th and 15th centuries AD. Radiocarbon dates of buried trees are consistent with those of nearby valley deposits linked to major medieval earthquakes, such that we can estimate average rates of re-incision since. We combine high-resolution digital elevation data, geodetic field surveys, aerial photos, and dated tree trunks to reconstruct geomorphic marker surfaces. The volumes of sediment relative to these surfaces require average net sediment yields of up to 4200 t km^–2 yr^–1 for the 650 years since the last inferred earthquake-triggered sediment pulse. The lithological composition of channel bedload differs from that of local bedrock, confirming that rivers are still mostly evacuating medieval valley fills, locally incising at rates of up to 0.2 m yr^–1. Pronounced knickpoints and epigenetic gorges at tributary junctions further illustrate the protracted fluvial response; only the distal portions of the earthquake-derived sediment wedges have been cut to near their base. Our results challenge the notion that mountain rivers recover speedily from earthquakes within years to decades. The valley fills around Pokhara show that even highly erosive Himalayan rivers may need more than several centuries to adjust to catastrophic perturbations. Our results motivate some rethinking of post-seismic hazard appraisals and infrastructural planning in active mountain regions. © 2018 John Wiley & Sons, Ltd.     

A multidisciplinary study of the Cape Peloro brackish area (Messina, Italy): characterisation of trophic conditions, microbial abundances and activities

In the framework of the VECTOR DIVCOST Project, a 2-year investigation was started in 2006, with the aim of testing the sensibility of microbial parameters to environmental changes and of assessing whether they can provide information about functional changes in the carbon cycle. The investigation was performed in the surface waters of two small brackish ponds (Ganzirri and Faro), located in the Cape Peloro transitional area (Sicily, Italy). The seasonal changes in both the microbial compartment [bacterioplankton, vibrios, exoenzymatic hydrolysis of proteins and polysaccharides, bacterial secondary production (HBP) and community respiration] and the trophic state of suspended matter [total suspended matter (TSM), particulate organic carbon (POC), particulate organic nitrogen (PON), C/N] were analysed in relation to the hydrological characteristics [temperature, salinity, oxygen, fluorescence, NH₄, NO₂, NO₃, PO₄]. Despite marked differences in the nutritional input and the diversification in both carbon budget and trophic level, the two ponds show similar trends in many of the investigated factors, hardly influenced by seasonal variations. Temporally coupled trends were observed for some parameters (enzyme activities, vibrios abundances, respiratory activity), whereas others (POC, PON, heterotrophic bacterial production, bacterioplankton) showed a seasonal shift between the two lakes. The different behaviour found for the some biotic parameters suggests that their response to environmental conditions may be modulated differently between the two lakes, which, despite their spatial proximity and reciprocal connection, do not always show contemporaneous functional processes.     

Adaptation of the SNOWMAP algorithm for snow mapping over eastern Canada using Landsat-TM imagery

Abstract

The snow mapping algorithm SNOWMAP was adapted to Landsat-TM data and to the context of eastern Canada. Six Landsat-5 TM scenes were used. It was found that the original version of SNOWMAP greatly underestimates snow cover extent. The modification made to the original algorithm, by cancelling the minimum threshold of 0.1 on the NDVI value, allows gaps to be filled in. In addition, a spatial correction procedure applied to the modified SNOWMAP algorithm results improves snow detection under coniferous forests. Based on a limited data set of ground-based observations (only 40 sites were available), the modified SNOWMAP seems to perform better in snow detection than the original version of the algorithm. An application case is presented in order to demonstrate the relevance of the modified SNOWMAP results as a high spatial-resolution reference for the validation of historical snow maps derived from medium spatial-resolution satellite data.

Citation Chokmani, K., Dever, K., Bernier, M., Gauthier, Y. & Paquet, L.-M. (2010) Adaptation of the SNOWMAP algorithm for snow mapping over eastern Canada using Landsat-TM imagery. Hydrol. Sci. J. 55(4), 649–660.     

Quantitative inter‐annual and decadal June–July–August temperature variability ca. 570 BC to AD 120 (Iron Age–Roman Period) reconstructed from the varved sediments of Lake Silvaplana,Switzerland

Annually resolved June–July–August (JJA) temperatures from ca. 570 BC to AD 120 (±100 a; approximately 690 varve years) were quantified from biogenic silica and chironomids (Type II regression; Standard Major Axis calibration‐in‐time) preserved in the varved sediments of Lake Silvaplana, Switzerland. Using 30 a (climatology) moving averages and detrended standard deviations (mean–variability change, MVC), moving linear trends, change points and wavelets, reconstructed temperatures were partitioned into a warmer (+0.3°C; ca. 570–351 BC), cooler (?0.2°C; ca. 350–16 BC) and moderate period (+0.1°C; ca. 15 BC to AD 120) relative to the reconstruction average (10.9°C; reference AD 1950–2000 = 9.8°C). Warm and variable JJA temperatures at the Late Iron Age–Roman Period transition (approximately 50 BC to AD 100 in this region) and a cold anomaly around 470 BC (Early–Late Iron Age) were inferred. Inter‐annual and decadal temperature variability was greater from ca. 570 BC to AD 120 than the last millennium, whereas multi‐decadal and lower‐frequency temperature variability were comparable, as evident in wavelet plots. Using MVC plots of reconstructed JJA temperatures from ca. 570 BC to AD 120, we verified current trends and European climate model outputs for the 21st century, which suggest increased inter‐annual summer temperature variability and extremes in a generally warmer climate (heteroscedasticity; hotspot of variability). We compared these results to MVC plots of instrumental and reconstructed temperatures (from the same sediment core and proxies but a different study) from AD 1177 to AD 2000. Our reconstructed JJA temperatures from ca. 570 BC to AD 120 showed that inter‐annual JJA temperature variability increased rapidly above a threshold of ～10°C mean JJA temperature. This increase accelerated with continued warming up to >11.5°C. We suggest that the Roman Period serves with respect to inter‐annual variability as an analogue for warmer 21st‐century JJA temperatures in the Alps. Copyright © 2011 John Wiley & Sons, Ltd.