Social networks and trade of services: modelling interregional flows with spatial and network autocorrelation effects

Recent literature on border effect has fostered research on informal barriers to trade and the role played by network dependencies. In relation to social networks, it has been shown that intensity of trade in goods is positively correlated with migration flows between pairs of countries/regions. In this article, we investigate whether such a relation also holds for interregional trade of services. We also consider whether interregional trade flows in services linked with tourism exhibit spatial and/or social network dependence. Conventional empirical gravity models assume the magnitude of bilateral flows between regions is independent of flows to/from regions located nearby in space, or flows to/from regions related through social/cultural/ethic network connections. With this aim, we provide estimates from a set of gravity models showing evidence of statistically significant spatial and network (demographic) dependence in the bilateral flows of the trade of services considered. The analysis has been applied to the Spanish intra- and interregional monetary flows of services from the accommodation, restaurants and travel agencies for the period 2000–2009, using alternative datasets for the migration stocks and definitions of network effects.     

Interactive Visualization Software to Improve Relief Interpretation Skills: Spatial Data Infrastructure Geoportal versus Augmented Reality

The improvement of geospatial thinking is essential for success in science, technology, engineering, and mathematics disciplines. Training based on the geovisualization and interpretation of landforms can develop the relief interpretation skill. The research reported here focuses on the study of relief visualization and interpretation, using results from a workshop performed with forty-six university students using different displays of geovisualization in a Spatial Data Infrastructure (SDI) geoportal: LiDAR digital surface model, HillShade digital terrain model, digital elevation model, slope model, high-resolution orthophoto, and topographic map. The results are compared with those of another workshop on the same topic carried out with augmented reality (AR) technology. The relief interpretation skill improvement was measured before and after each of the workshops using the Topographic Map Assessment test. The results with the SDI geoportal showed a significant gain in relief interpretation skill between pretest and posttest scores but less than the gain obtained with AR. No differences were found due to the gender of the participants in either case. Key Words: augmented reality, geospatial thinking, landform interpretation, relief interpretation skill, Spatial Data Infrastructure.     

Modelling spatio-temporal patterns of sediment yield and connectivity in a semi-arid catchment with the WASA-SED model

Abstract

Rainfall–runoff induced soil erosion causes important environmental degradation by reducing soil fertility and impacting on water availability as a consequence of sediment deposition in surface reservoirs used for water supply, particularly in semi-arid areas. However, erosion models developed on experimental plots cannot be directly applied to estimate sediment yield at the catchment scale, since sediment redistribution is also controlled by the transport conditions along the landscape. In particular, representation of landscape connectivity relating to sediment transfer from upslope areas to the river network is required. In this study, the WASA-SED model is used to assess the spatial and temporal patterns of water and sediment connectivity for a semi-arid meso-scale catchment (933 km²) in Brazil. It is shown how spatial and temporal patterns of sediment connectivity within the catchment change as a function of landscape and event characteristics. This explains the nonlinear catchment response in terms of sediment yield at the outlet.

Citation Medeiros, P. H. A., Güntner, A., Francke, T., Mamede, G. L. & de Araújo, J. C. (2010) Modelling spatio-temporal patterns of sediment yield and connectivity in a semi-arid catchment with the WASA-SED model. Hydrol. Sci. J. 55(4), 636–648.     

Macrobenthos and multi-molecular markers as indicators of environmental contamination in a South American port (Mar del Plata,Southwest Atlantic)

We evaluated benthic habitat quality along a presumed contamination gradient in the Mar del Plata port (Southwestern Atlantic) by coupling biological and chemical proxies in a multidisciplinary approach. Organic matter and photosynthetic pigment contents were higher in silty-clay bottoms of the inner port sites. Levels of all fecal steroids decreased from the inner sites to the port inlet. High concentrations of coprostanol in the inner sites seemed to derive from a permanent population of sea lions rather than from sewage outfalls due to coprostanol/epicoprostanol ratio (IV) values <2.5. PAHs levels were also higher in the inner sector, related to both biomass combustion and petroleum combustion associated to local marine traffic. High disturbance and low ecological status were reflected in low benthic diversity and high AMBI values in the inner sites.     

Multi-hydro hydrological modelling of a complex peri-urban catchment with storage basins comparing C-band and X-band radar rainfall data

ABSTRACT

The spread of impervious surfaces in urban areas combined with the rise in the intensity of rainfall events as a result of climate change has led to dangerous increases in storm water flows. This paper discusses a new implementation of the fully distributed hydrological model Multi-Hydro (developed at École des Ponts ParisTech), when operating storage basins, and its ability to deal with high-resolution radar rainfall data. The peri-urban area of Massy (south of Paris, France) was selected as a case study for having six of these drainage facilities, used extensively in flood control. Two radar rainfall datasets with different spatiotemporal resolutions were used: Météo-France’s PANTHER rainfall product (C-band) and ENPC’s X-band DPSRI. The rainfall spatiotemporal variability was analysed statistically using Universal Multifractals (UM). Finally, to validate the application, the water level simulations were compared with local measurements in the Cora storage basin located next to the catchment’s single outlet.     

Revisiting hydrocarbons source appraisal in sediments exposed to multiple inputs

The aim of this work was to test the efficiency of statistical methods as compared to the traditional diagnostic ratios to improve hydrocarbon source identification in sediments subjected to multiple inputs. Hydrocarbon determination in Guanabara Bay sediments pointed out high degradation and ubiquitous petrogenic pollution through the presence of high unresolved complex mixture. Polycyclic aromatic hydrocarbon (PAHs) ratios suggested pervasive contamination derived from combustion in all sediments and failed discriminating samples despite the specificity of sources in different sampling sites. Principal component analysis (PCA) effectively distinguished the petrogenic imprint superimposed to the ubiquitous combustion contamination, since this technique reduces the influence of PAHs distribution which is common to all samples. PCA associated to multivariate linear regression (MLR) allowed a quantitative assessment of sources confirming predominance of the pervasive contaminant component superimposed to a generalized petrogenic imprint. The pervasive component derives from combustion contributions as well as from differential PAHs degradation.     

Traditional ecological knowledge and community resilience to environmental extremes: A case study in Doñana,SW Spain

Research in the last decade has emphasised the potential contribution of traditional ecological knowledge to cope with challenges from global environmental change. This research examines the role of traditional ecological knowledge and shared systems of beliefs in building long-term social–ecological resilience to environmental extremes. Data were collected from 13 villages of the Doñana region, southwestern Spain, through interviews, focus groups, and systematic reviews of historical archives. First, we assess adaptive practices to cope with environmental change. Then, we use historical records of religious ceremonies (1577–1956) to reconstruct collective responses to environmental extremes. Our results (1) show how environmental extremes could induce social and economic crises through declines in ecosystem services and (2) identify practices to cope with recurrent disturbance and institutional devices developed in response to environmental extremes. We conclude that traditional ecological knowledge and shared systems of beliefs can facilitate collective responses to crises and contribute to the maintenance of long-term resilience of social–ecological systems.     

Throughfall enrichment and stream nutrient chemistry in small headwater catchments with different land cover in southern Chile

Land cover changes have a great impact on nitrogen (N) and phosphorous (P) fluxes catchments. In this study, we wanted to compare different land covers: deciduous (D), evergreen (E) (both native forests), and exotic Eucalyptus globulus plantation (EP), affected precipitation, and stream discharge on N and P species concentrations and fluxes, under a low deposition climate in south‐central Chile. For this, we collected bulk precipitation, throughfall, and stream water samples after 41 rainfall events in E and EP, during the period June 2009–March 2011, and 31 rainfall events in D, during the period October 2009–March 2011. The highest canopy enrichment of N and P species for throughfall was observed in deciduous forest, while E. globulus showed the minimum enrichment. Total nitrogen (total‐N) discharge in EP was about 8.6 times higher than that of E and D catchments. Total‐N annual retention was positive only in E and D catchments. However, EP catchment showed a net loss (?4.79 kg N ha/year). The biggest difference was observed in nitrate stream concentrations, which showed low values for E (3.4 ± 1.3 μg/L), while EP and D showed higher nitrate concentrations (84.9 ± 16.7 and 134.7 ± 36.7 μg/L, for EP and D, respectively). Total phosphorous (total‐P) discharge flux was low in EP (0.4 kg P ha/year), and negligible in E and D forests (<0.1 kg P ha/year). Total‐P annual retention was near to 1.0 kg N ha/year (on E and D), while a net loss (?1.5 kg N ha/year) was observed for EP. We attribute the observed differences in nutrient throughfall enrichment due to high multi‐stratified canopies in the native forests. Both deciduous and evergreen native forest‐covered catchments showed the highest retention of total‐N and total‐P, in contrast to Eucalyptus‐covered plantation.