O uso dos dados lidar para a compreensão da dinâmica de escoamento e acúmulo de águas em Recife – PE

Os grandes aglomerados urbanos desencadeiam profundas problemáticas de natureza hidroclimática, resultantes principalmente das formas de uso e ocupação do solo. Os padrões hídricos, tais como escoamento e acúmulo de fluxo, são afetados diretamente pelo efeito de impermeabilização do solo decorrente das construções humanas e quando esta estrutura urbana é somada aos eventos climáticos extremos, culminam na ocorrência periódica de inundações. Diante deste contexto, o presente estudo tem como objetivo compreender e identificar os danos hidrológicos decorrentes da concentração urbana, sobre a dinâmica natural do escoamento, a fim de investigar os fatores que provocam estas inundações nas determinadas regiões. A área de estudo do presente trabalho é representada por folhas de amostragem do sensor LiDAR das Regiões político administrativas IV e VI do município do Recife, Pernambuco. Para subsidiar a análise proposta, os modelos digitais de elevação do projeto Pernambuco 3D, provenientes do sensor LiDAR, foram processados em ambiente SIG, e a partir destes dados de alta resolução espacial foi possível analisar detalhadamente as variáveis que propiciam o escoamento superficial e acúmulo de fluxo nas áreas em estudo. Os resultados obtidos para as áreas de amostragem, foram analisados e comparados com as políticas públicas de drenagem urbana e planejamento territorial vigentes, avaliando a relação entre as redes de macro e microdrenagem, com a ocorrência de inundações no meio urbano. The use of lidar data for the understanding of water flow and accumulation dynamics in the Recife – PEA B S T R A C TLarge urban agglomerations result in huge problems of hydroclimatic nature, resulting mainly from the forms of land use and occupation. Water patterns, such as runoff and flow accumulation, are directly affected by the waterproofing effect from human constructions, and when added to the extreme weather events, they culminate in a periodic occurrence of urban floods. The study area of the present work is represented by the LiDAR sensor sampling sheets from the administrative political Regions IV and VI of the municipality of Recife, in Pernambuco. Given this context, the present study aims to understand and identify the hydrological damage caused by the urban concentration on the natural dynamics of runoff, to investigate the factors that cause these floods in that specific region. To subsidize the proposed analysis, the digital elevation models of the Pernambuco 3D project, from the LiDAR sensor, were processed in a GIS environment, and from these high spatial resolution data it was possible to analyze in detail the variables that propitiate surface runoff and flow accumulation in the areas under study. The results obtained for the sampling areas were analyzed and compared with the urban drainage and territorial planning public policies in force, evaluating the relationship between the macro and micro drainage networks, with the occurrence of floods in the urban environment. Keywords: Geoprocessing. remote sensing. urbanization. urban flood. surface runoff.

Distribution Matters: Sensitivity of Gridded Data of Population and Economic Conditions to Global Water Scarcity Assessment

Availability of water per capita is among the most fundamental water-scarcity indicators and has been used extensively in global grid-based water resources assessments. Recently, it has been extended to include the economic aspect, a proxy of the capability for water management. We applied the extended index globally under SSP–RCP scenarios using gridded population and economic conditions from two independent sources and unexpectedly found that the gridded data were significantly sensitive to global water-scarcity assessment. One projection assumed urban concentration of population and assets, whereas the other assumed dispersion. In analyses using multiple SSP–RCP scenarios representing a world of sustainability (SSP1–RCP2.6), regional rivalry (SSP3–RCP7.0), and fossil fuel development (SSP5–RCP8.5) in the future, multiple GCMs, and two gridded datasets showed that the water-scarce population ranges from 0.32–665 million. Uncertainties in the SSP–RCP and GCM scenarios were 6.58–489 million and 0.68–315 million, respectively. The population distribution assumption had a similar impact, with an uncertainty of 169–338 million. These results highlight the importance of the subregional distribution of socioeconomic factors for predicting the future global environment.

A combined approach for flood hazard assessment using hydrological, hydraulic and GIS modeling case study of El Hamiz Wadi, Algeria

Flood hazard is one of the most destructive natural phenomena causing a significant material damage and human losses in Algeria during the past decade. The aim of this study is to assess and characterize the flood hazard in El Hamiz watershed (Algeria). In addition, this study identifies areas and elements prone to this hazard to minimize the damages and losses. The methodology used in the present study is based on a combination of hydrological and hydraulic modeling using the Hec-Ras software and mapping techniques using a Geographic Information System (GIS). The flood hazard assessment model of El Hamiz wadi using different hydrological (rainfall / runoff transfer and return period), hydraulic (water level and flow velocity) and exposure (land use data and socio-economic data) parameters revealed that the downstream part of the studied area is the most susceptible to flood events. The mapping of flood-prone areas indicated the extent of this phenomena on the El Hamiz wadi banks, especially through heavy submersion of residential areas characterized by a high urban concentration including inhabitants, activities and infrastructures.

“Com duas gejas em cada uma das fontes”: escarificações e o processo de tradução visual da diáspora jeje em Minas Gerais durante o século XVIII

<p>Este artigo analisa os impactos da presença dos grupos de línguas gbe na formação do léxico empregado no detalhamento das cicatrizes rituais da população africana presente no distrito diamantino da capitania de Minas Gerais em meados do século XVIII. O enfoque é dado sobre o processo histórico de difusão do termo “geja”, explorando tanto os seus significados ligados a padrões específicos de escarificações como o seu uso generalizado para marcas corporais africanas, independentemente da origem étnica. Examina-se a sua emergência como índice de uma cadeia mais ampla de significados atrelados à etnogênese jeje em um contexto de grande concentração urbana de povos da Costa da Mina.</p><p>“With Two Gejas on Each Temple”: scarification and the process of visual translation in the jeje diaspora of 18th Century in Minas Gerais</p><p>Considering the visual culture of the African diaspora, this article analyzes the effects of the presence of Gbe language groups in the formation of the lexicon used in detailing the ritual scarification of the African population present in the diamond district of the captaincy of Minas Gerais in the eighteenth century. It focuses on the historical process of spreading the term geja, exploring both its meanings linked to specific patterns of scarification and its widespread use for African body markings in general. Its emergence is examined as an index of a broader chain of meanings connected to the Gbe ethnogenesis in a context of great urban concentration of people from Costa da Mina.</p><p>Jeje Nation | African Diaspora | Gejas | Scarification</p>

Does urban concentration matter for changes in country economic performance?

This paper uses a novel, globally harmonised city-level data set – with cities defined at the Functional Urban Area (FUA) level – to revisit the link between urban concentration and country-level economic dynamics. The empirical analysis, involving 108 low- and high-income countries, examines how differences in urban concentration impinge on changes in employment, Gross Domestic Product (GDP) per capita and labour productivity at country level over the period 2000–2016. The results indicate that urban concentration reduces employment growth but increases GDP per capita and labour productivity growth. The returns of urban concentration are higher for high- than for low-income countries and are mainly driven by the ‘core’ of FUAs, rather than by suburban areas.

Cities and Violence: An Empirical Analysis of the Case of Costa Rica

ABSTRACT This article focuses on the effect of urbanization on violent crime – particularly homicide in Costa Rica. Although violence is a major problem throughout Latin America, few empirical studies carried out in the area use high-quality socioeconomic and crime databases with a high level of geographical disaggregation. In this article, we employ data from all 473 districts of Costa Rica between 2010 and 2013. We develop a model which takes into account endogeneity problems and uses contrasts of marginal linear predictions. We conclude that the degree of urban concentration plays a key role in explaining homicide rates, other things being equal. This effect is progressive: the greater the urban concentration, the greater the increase in homicide rates. This causal relationship is not observed in offenses other than homicide.

The urbanising force of global warming: the role of climate change in the spatial distribution of population

We study the relationship between changes in weather patterns and the spatial distribution of population and economic activity within countries. Our unique global dataset combines climatic and census data for the period 1950–2015 with satellite data on built-up areas, and light intensity at night for the 1990–2015 periods. We establish a global non-linear effect of climate on urbanisation. In particular, we find that deteriorating climatic conditions are associated with more urbanisation. This happens across the whole urban structure, with urbanisation increasing in both smaller and larger cities. But, we also find that weather variation can alter the national urban structure, including the pattern of urban concentration, as well as the size, density and spatial structure of large cities.