It is essential to visualize water scarcity as a result of an inappropriate process of appropriation and the use of natural resources. This understanding has been gaining more and more prominence in studies in Brazil and also in the world. In this context, this research aims to map the risk of water shortages and sewage insufficiency in a Brazilian semi-arid city using GIS-MCDA. The secondary data used in this research were collected from IBGE, Compesa, and the City Hall of Caruaru and were processed using the QGIS 3.12 Bucareşti software. The Pernambuco Tridimensional database and the Analytical Hierarchy Process method were used in the process to generate the maps. After collecting and analyzing the data, it was seen that, according to the water shortage risk map, seven neighborhoods had a “Very high” risk, in which the criteria with the greatest weight were the distance from distribution reservoirs, the main supply network and altimetry. The map of the degree of sanitary sewage insufficiency showed that four neighborhoods have a “Very high” degree; these neighborhoods are far from the main sewage network and from sewage treatment stations and have the lowest rates of households served by the system. Such characteristics need to be highlighted in the planning and implementation of water and sewage services. Thus, it is concluded that the use of high-resolution spatial databases for the planning of urban services, as carried out in the present work, provides a greater level of confidence for solutions that can be implemented in the expansion of service networks to the population.

Vegetation indexes from remote sensing images are often used for land-cover monitoring and identification of biomass changes. They are also very useful to describe the relationships between the phenological cycle and the carbon sequestration, which are climate change indicators. The Caatinga land-cover is very heterogeneous, making hard the understanding of the land cover processes in different scales (spatial and temporal), due to seasonalities and human actions. The Landsat series products usually can describe spatial land-cover variations, with a low temporal scale, so far. This study aims to improve the temporal representation of the land cover by Landsat images for a Caatinga area. This article presents an evaluation, using a mathematical approach of three-parameter functions to describe the Normalized Difference Vegetation Index (NDVI). Each function performance was evaluated by the reduced chi-square (chi(2)) and determination coefficient (R-2) parameters. The analysis is performed for an annual period and considers land-cover changes by anthropic action. The Cauchy function seems the best option and presented an adjust up to 83% of the total (years and places), with an R-2 (average) of 0.82. The parameters of this function can be a valuable source for environmental studies in the Caatinga biome, supporting temporal analysis of the vegetation.

Cities keep growing, and in most of the cases this expansion process is hard to model and describe for planning actions. Quantitative methods are increasingly used to help planning, monitoring, and regulating urban land-use processes. Remote sensing images series are making possible different types of spatial-temporal analysis of the Earth surface. Surface albedo is a remote sensing product acquired in a long series of satellite images such as Landsat (more than 40 years of observation). Those analyses allow measuring waterproofed areas for urban drainage studies, as well as monitoring urban spreading patterns, growth vectors, and issues related to comfort and environmental quality, as well as about land use and land-use planning (directives for master plans) among others. This article shows the direct applicability of surface albedo changes as an indicator of urban land-cover changes. The current study analyzed the urban area of Petrolina County (PE) in the following periods: 2001 and 2006, 2006 and 2011, and 2011 and 2017. Such analysis uses the surface albedo variation along the time and results showed a strong correlation between increased surface albedo and urban expansion. Besides, it enabled to observe the relation between the high urban growth in the 2011-2017 period and the urban spot expansion by 14% (approximately 590 thousand square meters of territorial extension). The Urban development stood out in the Northern and Southwestern regions of Petrolina County.

The São Francisco River Integration Project was designed to reduce the impacts of droughts in the states of Brazilian semiarid. The article performs a temporal analysis of the water availability in the four PISF water receiving states, through the cross-tabulation of data referring to the water surface and the annual precipitation of the states in the period from 1985 to 2017. To identify the correlation between these two parameters and inferences that can be made from the results in the 33 years of analysis. The methodology consists in determining the correlation between the areas classified as water surface by the MapBiomas project and rainfall obtained by satellite. Water recurrence data from the Global Water Surface product are also used to validate the discussion about water availability. The results point to the multiannual drought that occurred since 2012 and the consequent loss of water surface of the states, besides identifying an increase of correlation in the states of Paraíba, Pernambuco and Rio Grande do Norte from the 90s. The results highlight the water management fragility of the states, and shows that the precipitation is not enough for the current demands.

Diante da histórica escassez de recursos hídricos na região semiárida, é notória a necessidade de se encontrar novas fontes de obtenção e armazenamento de água, seja para o consumo humano e animal ou para produção agrícola. A implantação de barragens subterrâneas no semiárido brasileiro pode contribuir de forma positiva na melhoria do abastecimento humano em comunidades rurais, além do fornecimento de água para o consumo animal e para produção de alimentos. Como sua construção se dá sobre os solos aluviais, o presente estudo tem como objetivo avaliar o potencial de aproveitamento desses solos no estado de Pernambuco para a implantação de barragens subterrâneas e verificar as áreas passíveis de salinização para a escolha adequada desse tipo de intervenção. A área de estudo corresponde ao estado de Pernambuco, em que a presença de solos aluviais foi observada por bacia hidrográfica, utilizando os dados do Zoneamento Agroecológico do Estado de Pernambuco (ZAPE). Com a mesma base de dados foram selecionados os solos com características salinas e estimada, por aluvião, a capacidade de armazenamento de água. Foi possível verificar que o estado de Pernambuco apresenta consideráveis áreas de solos aluviais, com potencial para aproveitamento das águas subterrâneas e para construção de barragens subterrâneas, bem como identificar as regiões onde a implantação desse tipo de obra deve ser mais restritiva por conta do risco de salinização. Evaluation of the Alluvial Use Potential for a Construction of Underground Dams in the Semi-Arid Region of PernambucoA B S T R A C TGiven the historical scarcity of water resources in the semi-arid region, it is clear the need to find new sources for obtaining and storing water, either for human and animal consumption or for agricultural production. The establishment of underground dams in the Brazilian semi-arid region can contribute positively to the improvement of human supply in rural communities, as well as the supply of water for animal consumption and food production. As its construction takes place on alluvial soils, the present study aims to evaluate the potential use of alluvial soils in the state of Pernambuco for the implantation of underground dams and to verify the salinization areas for the appropriate choice of this type of intervention. The study area corresponds to the state of Pernambuco, where the presence of alluvial soils was observed by watershed, using data from Pernambuco State Agroecological Zoning (ZAPE). With the same database were selected soils with saline characteristics and estimated, in each alluvium, water storage capacity. It was possible to verify that the state of Pernambuco has areas considerable of alluvial soils, with potential for groundwater utilization and for the construction of underground dams, as well as to identify the regions where the implementation of this type of work should be more restrictive due to the risk of salinization.Keywords: groundwater, alluvium, subsurface dam, risk of salinization.

A gestão eficiente dos recursos hídricos no Nordeste brasileiro torna-se fundamental diante do regime hidrológico dos rios intermitentes, dos quais muitos são extremamente críticos. Todavia estes dependem de um regime pluviométrico irregular, tanto em escala de tempo mensal quanto anual. Objetivou-se determinar a variabilidade espaço-temporal da precipitação pluviométrica total anual, averiguando-se, também, as regiões com padrões de precipitação semelhantes por técnicas de análise multivariada (clusters e componentes principais) no Nordeste do Brasil. Foram analisados dados de precipitação pluviométrica total anual, entre os anos de 1995 e 2016, de 37 diferentes estações meteorológicas do INMET, estas situadas nos limites territoriais dos nove estados do Nordeste brasileiro. A análise de clusters verificou a formação de quatro grupos distintos, com padrões semelhantes de precipitação nas regiões dentro dos grupos, conforme também observado na análise de componentes principais. A padronização e/ou variabilidade espaço-temporal da precipitação pluviométrica dos municípios analisados mostrou-se está intimamente associada as condições das estações do ano e anomalias climatológicas, aos fatores de uso e ocupação do solo, condições de altitude e relevo, tais quais favorecem na formação e estabilidade de chuvas menores ou maiores no Nordeste brasileiro. A análise multivariada de cluster e componentes principal identificaram padrões e semelhanças pluviométricas de grupos, nos diferentes estados do Nordeste do Brasil entre os anos de 1995 e 2016. Exploratory Inference of Spatial-Temporal Data of Rainfall in the Brazilian Northeast ABSTRACTThe efficient management of water resources in the Northeast of Brazil is essential in view of the hydrological regime of intermittent rivers, of which many are extremely critical, as they depend on an irregular rainfall regime, both on a monthly and annual time scale. The objective of this study was to determine the spatial and temporal variability of the annual total rainfall, also investigating the regions with similar rainfall patterns by multivariate analysis techniques (clusters and principal components) in Brazilian Northeast. Data from total annual rainfall between the years 1995 and 2016, of 37 different INMET weather stations were analyzed, located within the territorial limit of the nine states of Brazilian Northeast. Cluster analysis verified the formation of four distinct groups, with similar precipitation patterns in the regions within the groups as also observed in the principal component analysis. The pattern and/or spatial-temporal variability of rainfall in the municipalities analyzed was shown to be intimately associated with the conditions of the year and climatic anomalies stations, and the factors of land use and occupation, altitude and relief conditions, such as favoring the formation and stability of minor or major rain in the Brazilian Northeast. Multivariate cluster and principal component analysis identified rainfall patterns and similarities of groups, in the different states of Northeastern Brazil between the years 1995 and 2016.Keywords: multivariate analysis, climate change, semiarid, regional climate patterns.