Spatial Distribution Of Areas Research Articles

Seawater intrusion-triggered high fluoride groundwater development on the eastern coast of China.

High-fluoride groundwater is commonly found in coastal areas worldwide, while its formation mechanism remains elusive. Herein, a comprehensive study was performed to identify the major controlling factor of high-fluoride groundwater occurrence along the eastern coast of China. Hydrogeochemical methods were employed to examine the distribution patterns of seawater intrusion and fluoride concentration and the impact of seawater intrusion on the fluoride concentration. The results indicate that seawater intrusion significantly influences the groundwater evolution process in the study areas. The groundwater in Laizhou Bay was affected by brine, and the groundwater in Tianjin and Jiangsu was affected by seawater with a mixing ratio lower than 40% and 20%, respectively. And the fluoride concentration in groundwater from Tianjin, Laizhou Bay, and Jiangsu generally exceeded 1mg/L, with the average of 2.3mg/L, 24.9mg/L, and 34.6mg/L, respectively. Both the degree of seawater intrusion and the fluoride concentration exhibit a consistent pattern: Laizhou Bay > Tianjin > Jiangsu. Cl- concentration in groundwater varies positively with the F- concentration (y = 0.66x - 1.31). Moreover, the spatial distribution of areas with high-fluoride groundwater mirrors that of seawater intrusion. The high-fluoride groundwater varies spatially and is related to the degree, stage, and type of seawater intrusion. In other words, when seawater intrusion intensifies more or groundwater in the freshwater renewal phase with higher Na+/Ca2+ or the presence of paleo-seawater intrusion with higher fluoride concentration of brine, the concentration of fluoride in groundwater is higher. As seawater intrusion intensifies, the high-fluoride groundwater in the study areas generally poses a higher health risk to human. These findings enhance our comprehension of the mechanisms underpinning high-fluoride groundwater in coastal regions and the environmental ramifications of seawater intrusion.

EXTREME HEAT VULNERABILITY AMONG OLDER ADULTS: A MULTILEVEL RISK INDEX FOR PORTLAND, OREGON

Abstract Extreme heat is an environmental health equity concern disproportionately impacting low- income older adults and people of color. Exposure factors, such as living in rental housing and lack of air conditioning, and sensitivity factors, such as chronic disease and social isolation, increase mortality risk among older adults. Older persons face multiple barriers to adaptive heat mitigation, particularly for those living in historically temperate climates. This study measures two heat vulnerability indices to identify areas and individuals most vulnerable to extreme heat and discusses opportunities to mitigate vulnerability among older adults. We constructed two heat vulnerability indices for the Portland, Oregon metropolitan area: one using area scale proxy measures extracted from existing regional data and another at the individual scale using survey data collected following the 2021 Pacific Northwest Heat Dome event. These indices were analyzed using principal component analysis (PCA) and Geographic Information Systems (GIS). Results indicate that the spatial distribution of areas and individuals vulnerable to extreme heat are quite different. The only area found among the most vulnerable on both indices has the largest agglomeration of age- and income-restricted rental housing in the metropolitan area. Due to spatial variations in heat-related risk at the individual and area scales, measures addressing heat risk should not be spatially uniform. By focusing resources on older adult individuals and areas in particular need of assistance, heat risk management policies can be both highly efficient and cost-effective.

Extreme Heat Vulnerability Among Older Adults: A Multilevel Risk Index for Portland, Oregon.

Extreme heat is an environmental health equity concern disproportionately affecting low-income older adults and people of color. Exposure factors, such as living in rental housing and lack of air conditioning, and sensitivity factors, such as chronic disease and social isolation, increase mortality risk among older adults. Older persons face multiple barriers to adaptive heat mitigation, particularly those living in historically temperate climates. This study measures two heat vulnerability indices to identify areas and individuals most vulnerable to extreme heat and discusses opportunities to mitigate vulnerability among older adults. We constructed two heat vulnerability indices for the Portland, OR, metropolitan area: one using area scale proxy measures extracted from existing regional data and another at the individual scale using survey data collected following the 2021 Pacific Northwest Heat Dome event. These indices were analyzed using principal component analysis and Geographic Information Systems. Results indicate that the spatial distribution of areas and individuals vulnerable to extreme heat are quite different. The only area found among the most vulnerable on both indices has the largest agglomeration of age- and income-restricted rental housing in the metropolitan area. Due to spatial variations in heat-related risk at the individual and area scales, measures addressing heat risk should not be spatially uniform. By focusing resources on older adult individuals and areas in particular need of assistance, heat risk management policies can be both highly efficient and cost effective.

Analysis of the quality of primary forest accessibility: the case study

Relative forest accessibility percent of accessible forest area by forest roads in comparison with total forest area is the most important indicator of the quality of primary forest accessibility. The accessible forest area by forest roads is determined by the bounded area around forest roads. Today, in the area with steep and variable slopes of terrain, a double targeted geometrical extraction distance of timber is used for the width of the bounded area around forest roads, and the forest road spacing is used in the area with a mild and uniform slope of the terrain. Both parameters depend on the targeted density of forest roads. Modern information technologies (IT) like geographical information systems (GIS) enable the quality spatial and statistical analysis of different kinds of data whose result is not accessible forest areas by current primary forest traffic infrastructure only, but also an insight into the spatial distribution of insufficient accessible areas into the forest area. The spatial distribution of these areas is significant for spatial distribution of the new routes of forest roads. The research is done in the area of Forest Management Unit (FMU) Prosara, for which the spatial analysis of a digital terrain model (DTM) determined the mostly hilly relief area. The average relative forest accessibility, based on double targeted geometrical extraction distance of timber, is 35% for the actual network of forest roads, and targeted forest road spacing is 60% for the upgraded network of forest roads.

Assessment and spatial partitioning of ecosystem services importance in Giant Panda National Park: To provide targeted ecological protection.

Giant Panda National Park is crucial for China's ecological security strategic pattern known as "two screens and three belts." The importance assessment and classification of ecosystem services in giant panda national parks has an important guiding role in the protection of giant panda national park ecosystems. In this study, we examined four indicators of habitat quality: carbon storage, water conservation, and soil and water conservation. Combined with data analysis were used to evaluate and classify the importance of ecosystem services in the study area. The results showed that: (1) the overall habitat quality index in the study area was relatively high, and the index was generally greater than 0.5. The total carbon storage was 60.5 × 106 t, and the highest carbon storage in the region was 16.9533 t. The area with the highest water conservation reached 715.275 mm. The total soil conservation was 2555.7 × 107 t. (2) From the perspective of spatial characteristics, the habitat quality in the study area presented a spatial distribution pattern of high-low from west to east. The carbon storage presented a spatial distribution pattern of high-low from east to west. The soil conservation presented a spatial pattern of decreasing from west to east, and the water conservation increased from west to east. (3) We divided the research into four levels of importance: The area of general importance in the study site accounted for 1017.58 km2 and was distributed in the northwest of the study site. The moderately important areas were distributed in the east of the study site, with an area of 1142.40 km2. The highly important areas were distributed in the west of the study site, totaling 2647.84 km2. Extremely important areas were distributed in the middle, with an area of 1451.32 km2. (4) The grid cell scale of the study area was used as the dataset to determine the weighting. This makes the weighting more objective and ensures that the spatial distribution of areas with different degrees of importance will be more accurate.

Prevalence of bovine fascioliasis, areas at risk and ensuing losses in the state of Goiás, Brazil.

The present study had to determine the prevalence and spatial distribution of areas at risk of bovine fascioliasis in the state of Goiás, central-western Brazil between 2007 and 2014; to evaluate the associations of some epidemiological variables with occurrences of Fasciola hepatica in animals; and to estimate the economic losses that this parasite on the cattle industry. It could be concluded that of 23,255,979 animals slaughtered, the average prevalence of F. hepatica in cattle in Goiás during the period evaluated was 0.0026% (95% CI: 0.0024-0.0028). In the State of Goias, in about then years (since when this parasite was found for the first time by other researchers in 2007), F. hepatica was diagnosed in 168 new municipalities. Using the regression analysis, the effective bovine herd size was a significant risk factor (OR= 1.21; 95% CI 1.1022-1.4510; p ≤ 0.05) for cattle to be infected with fascioliasis in the state of Goiás. The cattle-rearing industry lost approximately R$ 15,072.75 (US$ 4,785) due to condemn of livers with Fasciola in the state of Goiás. New studies need to be conducted in these regions, with the aim to identify the likelihood of presence of intermediate hosts, which might serve as a source of F. hepatica infection for definitive hosts.

The Influence of Shallow Taliks on Permafrost Thaw and Active Layer Dynamics in Subarctic Canada

AbstractMeasurements of active layer thickness (ALT) are typically taken at the end of summer, a time synonymous with maximum thaw depth. By definition, the active layer is the layer above permafrost that freezes and thaws annually. This study, conducted in peatlands of subarctic Canada, in the zone of thawing discontinuous permafrost, demonstrates that the entire thickness of ground atop permafrost does not always refreeze over winter. In these instances, a talik exists between the permafrost and active layer, and ALT must therefore be measured by the depth of refreeze at the end of winter. As talik thickness increases at the expense of the underlying permafrost, ALT is shown to simultaneously decrease. This suggests that the active layer has a maximum thickness that is controlled by the amount of energy lost from the ground to the atmosphere during winter. The taliks documented in this study are relatively thin (<2 m) and exist on forested peat plateaus. The presence of taliks greatly affects the stability of the underlying permafrost. Vertical permafrost thaw was found to be significantly greater in areas with taliks (0.07 m year−1) than without (0.01 m year−1). Furthermore, the spatial distribution of areas with taliks increased between 2011 and 2015 from 20% to 48%, a phenomenon likely caused by an anomalously large ground heat flux input in 2012. Rapid talik development and accelerated permafrost thaw indicates that permafrost loss may exhibit a nonlinear response to warming temperatures. Documentation of refreeze depths and talik development is needed across the circumpolar north.

The Use of Indicator Kriging for Analyzing Prices in the Real Estate Market

Abstract The patterns and relations between real estate prices and the factors which shape them can be presented, among others, in the form of traditional statistical models, as well as by means of geostatistical methods. In the case of research involving the diagnosis and prediction of transaction prices, the key role is played by the spatial aspect, hence the particular significance of geostatistical methods using spatial information. The main goal of the conducted research is to determine the probability of the occurrence of a price in a given location in space by means of geostatistical simulation - indicator kriging. Indicator kriging does not use the entirety of information included in a dataset, and can, therefore, be useful in situations when the assumptions involving the spatial stationarity of the examined phenomenon are not fulfilled by an entire dataset, but are fulfilled by a certain part of the set. The maps of the probability with which a regionalized variable (price) takes on particular values, limited by arbitrarily selected cutoff values, were prepared by means of indicator kriging. An alternative approach to the preparation of price probability maps is the determination of the spatial distribution of areas in which, with the assumed probability, the value of the price falls within the predetermined ranges. The paper presents both the essence as well as a theoretical description of the geostatistical simulation of a transaction on the real estate market, as well as the results of an experiment involving the transaction prices of real properties located in the north-western part of the city of Olsztyn. The result of the research is a set of virtual information about the places in which the transactions have occurred and about the prices of real estate, constituting a reflection of the market processes which may take place in the near future.

Spatial Planning for Promoting Sustainable Development in Pachchilaipalli Divisional Secretariat in the Killinochchi District of Sri Lanka- A Case Study for Post-Conflict Development

Reconstruction and development in post-disaster or post conflict situations pose multiple challenges. These scenarios necessitate high investment for rapid reconstruction, socio-economic development to minimize future conflicts or disasters, and opportunities to introduce; landuse planning, environmental, engineering and other best practices for increased sustainability and resilience. The post-conflict situation in the Killinochchi District presents a scenario with agencies having outdated data, missing critical information, an intensive development drive which exerts pressures on nature, culture and large number of scattered development plans. The study involves three stages, namely, establishment of baseline data, analysis of digital data and development of a zoning map as a proposed landuse. This facilitates the decision making in development activities within the area with environmnetal conservation, and coordinates stakeholder agencies for sustainable development. The entire Killinochchi District was divided in to 92 equal grids for micro level planning and 5 Km2 area in Pachchilaipalli DS Division was selected to initiate the case study. The topographical survey maps developed in 1956, 1983 and 2010 were used for spatial analysis, and to compare the landuse changes occurred during the last 57 years in the area of study. Arc GIS 10.1 software was used to develop spatial maps of different sectors. The zoning map which was prepared as the proposed landuse plan illustrates the spatial distribution of areas for development with minimum environmental impacts as the key output of the study.

A multi-sensor approach for mapping plant-derived carbon storage in Amazonian podzols

The Rio Negro basin is characterized by the extensive occurrence of podzol-type soils that store large amounts of organic matter in depth, resulting in the storage of carbon able available to the atmosphere with climate change. The quantification of this carbon requires determination of podzol types and their spatial distribution. Remote-sensing techniques would be helpful in indirect spatializing and segmentation of soil groups in Amazonian podzols. Here we associated remote-sensing images (Shuttle Radar Topographic Mission (SRTM), Operational Land Imager sensor/Landsat 8, and Thermal Infrared Sensor/Landsat 8) and field sample data in order to achieve carbon stock mapping. We found that a multi-sensor approach was critical for a proper segmentation of vegetation groups and spatial distribution of areas with different hydrologic soil regimes.

An appraisal of the usefulness of LandSat5_TM imageries in groundwater reconnaissance studies in Zaria – Kaduna area, north central Nigeria

In order to assess the usefulness of remote sensing to groundwater resources studies especially with regard to the location of aquifers in the hard rock terrain, Landsat5_TM imageries were used in the Zaria – Kaduna area. In that area some information on the groundwater and the aquifers were already available. Image interpretation was carried out in two parts. In the first part, a structural interpretation was done by marking lineaments (fractures), from which their density (length/km2) per cell of 2.5 km x 2.5 km was calculated for the entire area. On the basis of the various values within the cells, a symbology of relative abundance of fractures in the area was created using classes to show the spatial distribution of areas where the fracture aquifer is likely to be encountered. The second part of the interpretation involved a spectral analysis and this was carried out employing the tasseled cap transformation. From the spectral analysis areas likely to produce good yields of water from the regolith aquifer were identified using interpretation keys. From the analysis of the fracture density areas that are favourable for the accumulation of groundwater in fracture aquifer were identified. Similarly, the relative variation of depth to the water table inferred from the spectral analysis was used to deduce areas that are favourably disposed to yield groundwater from the regolith aquifer. The surface information obtained from both the structural and the spectral analyses can serve useful reconnaissance purposes. KEY WORDS: Groundwater, basement rocks, Landsat5_TM, fracture aquifer, regolith aquifer, Nigeria

Recognition of shallow karst water resources and cave potentials using thermal infrared image and terrain characteristics in semi-arid regions of Iran

Shallow karst water resources and caves may influence land surface temperatures due to cold transfer property of rocks and evaporation from buried karst. The objective of this research was to develop a method for recognition of karst areas based on evaluating the surface characteristics that manifest itself by low land surface temperature in the satellite images. Investigation of thermal ETM+ image of the study region in Iran showed that parts of carbonate rocks that bear karst water are relatively cooler compared to areas with similar terrain conditions. Relational modeling provided useful information on spatial distribution of areas that have the potential to hold karst water resources and/or caves. Further inspection of ASTER images, along with geotechnical, geophysical and geological field surveys verified the approach. Significant correlation was found between electrical resistivity and thermal band values. The method may be used as a primary exploratory tool for shallow karst water explorations in similar areas.

Quantitative evaluation of porosity in aluminum alloy die castings by fractal analysis of spatial distribution of area

High-pressure die-casting processes are widely used, especially for automotive products, but pores in the die-casting process occasionally occur during production. To identify the cause of porosity and to take corrective action in the die-casting process accurately and rapidly, a quantitative estimation of the morphology of pores can be an effective technique. In this study, fractal analysis is proposed to characterize porosity quantitatively in terms of the spatial distribution of a number of pores appearing in a target region. The purpose of the present investigation is to evaluate the proposed fractal analysis by comparing the porosity in two types of aluminum alloy die castings manufactured by different die-casting processes, and to confirm that fractal analysis of the spatial distribution of pores can quantitatively characterize the porosity.

Mapping the annual area burned in the wetlands of the Okavango panhandle using a hierarchical classification approach

This paper documents the methodology developed to identify burned areas accurately, and to quantify the spatial extent of the areas burned, in the wetlands of Botswana’s Okavango panhandle in 2001. Physical identification of burned areas in marshy wetlands is extremely difficult. Burned areas are short-lived, limiting opportunities for ground-based measurement, which is often further hampered by extreme inaccessibility, and the unpredictable nature of the location and timing of burning. Given these challenges, satellite imagery has the potential to provide an excellent alternative for such analyses. However, burned areas can be spectrally confused with non-vegetated wetland areas such as open water and muddy flats, particularly when relying predominantly on the near-infrared band. This study addresses these constraints by using a hierarchical classification of Landsat 7 ETM+ imagery to remove wet and well-vegetated areas prior to burned-area identification, and by using the thermal band data to improve the separation between wet and burned areas. These techniques resulted in good designation of burned areas, a reduction in the misclassification of unburned areas, and a refinement of the spatial distribution of areas burned in 2001. The approach should prove useful to practitioners seeking to manage fire in wetlands.

Changing rainfall and its impact on landslides in Sri Lanka

During the recent past the rainfall pattern in Sri Lanka has shown a noticeable change. This paper describes the effect of this change on the occurrence of landslides and their impacts to eco systems. This study shows that most of the landslides occurring in Sri Lanka during northeast monsoons, southwest monsoons and second inter-monsoon were located in three distinctively separated areas. Analysis of rainfall time series shows a trend of increased lengths of dry periods along with an increasing trend of rainfall intensity, especially after the late seventies. A strong relation is obtained between the location of landslides and the spatial distribution of areas where rainfall intensity is increased.

Assessing atrazine pollution potential to a drinking water reservoir using remote sensing and geographic information system modeling

Abstract Water quality monitoring by the City of Dallas, Texas (US) and the Institute of Applied Science, University of North Texas, has recently shown elevated atrazine concentrations in the watershed of a large drinking water reservoir in the Dallas-Fort Worth metropolitan area serving over 3,000,000 people. Atrazine is under investigation by numerous researchers as an environmental estrogen that may be involved in increasing breast cancer incidence in humans and impacting health and reproductive systems in wildlife. Since treatment technologies for atrazine removal from finished drinking water can be expensive and provide no protection to aquatic ecosystem health, watershed managers are currently seeking proactive methods to reduce the amount of atrazine entering water supply systems. The most viable approach for reducing atrazine in a drinking water reservoir begins with understanding the distribution and extent of landuse in the watershed where atrazine may be applied. Understanding the spatial distribution of areas potentially contributing atrazine runoff facilitates developing an effective atrazine reduction program of the best management practices that are appropriate to a particular region. Using remotely sensed satellite imagery and geographic information system modeling, an analysis of the spatial distribution of landuse, soil erodibility, and surface slope information in a large watershed in north central Texas was conducted. An ‘atrazine pollution potential’ model was developed and applied to over 224,000 hectares draining into Lake Lewisville which provides drinking water to Dallas and surrounding communities. Model results compared well with in situ water quality measurements of atrazine, and point to areas most in need of best management practice implementation.

Multiple-scale habitat modeling approach for rare plant conservation

Multiple-scale habitat assessment for rare plants is an important component of conservation and development planning. It is challenging, however, due to lack of information synthesis on the ecology of rare plants, lack of effective approaches for habitat assessment at multiple spatial scales, and lack of spatial data for relevant environmental attributes and scales. A multiple-scale habitat modeling approach was developed to meet this need. Regional-, landscape-, and site-scale habitat models were developed for eight rare plant species found in southern Texas, USA. The models were partially validated and used for planning of rare plant conservation and highway construction. Regional-scale habitat models were used to predict, based on coarse-scale geographic information system (GIS) data, spatial distribution of areas containing potential habitat of rare plant species and the probability of encountering potential rare plant habitats. Site-scale models, based on synthesis of the literature and field investigations, were developed for field survey and mapping of rare plant habitats to enable accurate assessment of potential and present habitat suitability of specific locations using fine-resolution field data on soil, landform and vegetation structure. The greatest need for assessing the presence and potential habitat of rare plants is at the landscape scales. Thus, landscape-scale models were developed for spatially explicit assessment of potential and present habitat suitability, based on site-scale models but using GIS and remote sensing-based data. These models can be used as effective tools for conservation planning, monitoring and management of rare plant habitat, as well as for reduction of land use conflicts and development cost. The processes of model development and application synthesizes the diffuse literature, identifies knowledge and data gaps to guide future research, and provides a framework for assimilating new information acquired in the future to improve habitat assessment.

Analysis of the spatial distribution of net primary productivity across Corsica (France) using the echelon approach

One of the main directions of research for ecologists studying the Earth as a global system is the search for quantitative methods for mapping and monitoring broad-scale patterns of net primary productivity (NPP). While all monitoring activities have a spatial context to a varying degree, the monitoring of NPP patterns requires an objective, criterion-based method for characterizing the spatial distribution of areas that are high or low in NPP relative to their surroundings. In this Letter, we apply a topology-based methodology called the 'echelon approach' to characterize the spatial structure of the remotely sensed NPP spatial structure across the island of Corsica (France) using a coarse-grained grid consisting of annually integrated Normalized Difference Vegetation Index (NDVI) values. Results show that the echelon approach provides a new perspective to objectively characterize the structural complexity of a tessellated surface variable for environmental monitoring purposes.

Modelling topographic potential for erosion and deposition using GIS

Abstract Modelling of erosion and deposition in complex terrain within a geographical information system (GIS) requires a high resolution digital elevation model (DEM), reliable estimation of topographic parameters, and formulation of erosion models adequate for digital representation of spatially distributed parameters. Regularized spline with tension was integrated within a GIS for computation of DEMs and topographic parameters from digitized contours or other point elevation data. For construction of flow lines and computation of upslope contributing areas an algorithm based on vector-grid approach was developed. The spatial distribution of areas with topographic potential for erosion or deposition was then modelled using the approach based on the unit stream power and directional derivatives of surface representing the sediment transport capacity. The methods presented are illustrated on study areas in central Illinois and the Yakima Ridge, Washington.