ArcGIS Analysis Research Articles

ASSESSMENT OF PROBABLE FOUNDATION PROBLEMS USING GEOPHYSICAL AND REMOTELY SENSED DATA IN A TYPICAL BASEMENT COMPLEX, SOUTHWESTERN NIGERIA.

This research work asses the problems of building foundation within Sagari Estate, Akure, Southwestern Nigeria, using remotely sensed data and geophysical methods. The slope, lineament, hill, and contour map were generated using terrain analysis in ArcGIS 10.5 environment. Electrical Resistivity (ER) and Very Low Frequency (EM-VLF) Electromagnetic methods were used in this study. The ER method involves the use of Vertical Electrical Sounding (VES) with Schlumberger configuration. The initial geoelectric parameters obtained from the fifty three (53) VES station points interpretation (layer resistivities and thicknesses) were used to generate geoelectric maps. The variation of strata and physical strength information within the investigated area were determined from the integrated results of the three methods. Results revealed that substantial portion of the areas studied is relatively unsuitable for high rise civil engineering foundations. However, it was showed that the northern and southern parts of the investigated area were more suitable for foundations. The dominant presence of lineaments, steep slopes , fractures, streams, and thick clayey topsoil as well as weathered layers within the western, eastern, and the central portions reveals susceptibility to subsidence if adequate structural supports mitigate the effect of the persistent foundation failure are not provided.

APLIKASI SISTEM INFORMASI GEOGRAFIS TERHADAP MANAJEMEN TRANSPORTASI DARI TPH KE PKS

This study aims to create a transportation management database, create a participatory map of the harvest path from the TPH to Mill and create a transportation management model in palm oil plantations. The study was conducted at PT. Langkat Nusantara Kepong (LNK) Tanjung Beringin Estate, Hinai District, Langkat Regency, North Sumatra. This research was conducted in May - June 2019.
 This research was conducted by direct measurement in the field and navigation analysis. Direct measurements in the field are done by calculating the distance from TPH to Mill, calculating the average speed of trucks when carrying FFB to Mill, calculating truck time from TPH to Mill. To measure the distance done using GPS Garmin then data from GPS is entered and analyzed with the ArcGIS program. Navigation analysis is carried out using Network Analysis in ArcGIS, where the work of Network Analysis will find the most effective and efficient way.
 Roads in Tanjung Beringin Gardens are distinguished by their functions as HW (Highway), MR (Main Road), CR (Collection Road) and BR (Boundrest Road). Map of the FFB transportation path from TPH to Mill via the CR line which then passes the MR, and passes the HW that corresponds to the truck lane. The results of research conducted by direct measurement in the field of FFB to Mill are already effective and efficient compared to navigation analysis.
 Keywords: Navigation Analysis, GIS, TPH, harvest transportation, palm oil

Evaluation of Locational and Environmental Effects of Religious Centres on Adjoining Development in Ibadan, Nigeria

This study assesses locational and environmental effects of religious centres on adjourning development in Ibadan South-East Local Government, Oyo State, Nigeria. Primary and secondary data were utilized. Geographic coordinates of religious centres were collected using GPS for a location-based mapping and nearest neighbour analysis in ArcGIS 10.3. A Multi-stage sampling technique was employed and systematic sampling procedure was used to administered 210 copies of questionnaires to respondents. The data were analysed using descriptive statistics which were frequency distribution and absolute mean in SPSS. Results showed that the nearest neighbour index (Rn) is 0.01 with critical value of <-2.58, p-value is 0.704138 and the nearest neighbour ratio equals 0.61799. Most religious centres were located without planning development permits and therefore are restricted by law to operate in the residential areas they were sited. Other key findings were based on three indices that were developed which are Proliferation Influencing Index (PII), Environmental Impact Index (EII) and Precaution Measures Index (PMI). The highest PII of 3.82 indicated that the proliferation of religious centres is majorly caused by “beliefs and practices”. An EII of 4.03 showed that environmental impact is highly due to “non-compliance with conditions of existing consents already in place” while “payment of fine by defaulters” with the highest PMI of 3.85 is the most used control measure. This study concludes that religious centres have been encouraged in residential areas by use of fines as against the enforcement of planning regulations as contained appropriately in urban and planning regional law.

ANALYSIS OF THE STATE OF PLANT COMMUNITIES IN THE DOLINSKY NATURE SANCTUARY (SAKHALIN) ACCORDING TO SATELLITE SURVEYS

The determination ratio of timber tree in the composition of stands makes it possible to judge about geoecological state of the vegetation cover. It be noted heterogeneous studying of forests in different regions of the country, in connection with which the research of specially protected natural areas (SPNA), which includes the Dolinsky Nature Sanctuary, with an insufficient number of employees in the forest industry, becomes especially relevant. Automated decoding of remote sensing data serves as an aid to ground-based observations. Work to identify the species composition of forests according to aerospace surveys on the territory of Sakhalin Island previously carried out in small volumes. The Sentinel-2 satellite images of the territory of the Dolinsky Nature Sanctuary, obtained in 2018-2021, analyzed in order to identify the classification features of various plant communities characteristic of the southern part of Sakhalin. On basis of visual interpretation, reference sites for geobotanical studies were identified, which with a high degree of confidence attributed to specific plant formations: fir-spruce, stone-birch, willow-alder river valleys, bamboo, deforested areas and plantings of pine and larch crops. Further work carried out using the methods of geoinformation analysis in ArcGIS. The optimal combinations of channels in the formation of synthesized image composites for the selection of training samples for each plant formation were determined when performing vegetation classification. In case of difficulties with the separation of some formations (larch - pine) in the images, the work carried out based on the materials of multi-season surveys. The obtained characteristics of the training samples can be used for further research in the Dolinsky Nature Sanctuary and beyond.

Estimating Mass Balance of White Glacier using ICESat-2

White Glacier is located on Axel Heiberg Island in Nunavut, Canada, and has had its mass balance actively monitored since 1960. Due to COVID-19 travel restrictions it not possible for researchers to travel to White Glacier and perform the measurements required. This results in gaps in data required to determine the mass balance for 2018-2020. In this study we aim to collect and process laser altimeter data to be interpolated to calculate an estimate of the Mass Balance of White Glacier. This study will be completed using a geodetic technique that utilizes the Ice Cloud and Elevation-2 (ICESat-2) satellite altimetry data. ICESat-2 is carrying ATLAS which is an Advanced Topographic Laser Altimeter that is equipped with six laser beams divided into three pairs that measure lidar altimetry to derive surface height. The longitude, latitude, datetime, and land ice height values were extracted over the Expedition fjord region using MATLAB. The land ice tracks were brought into ArcGIS for analysis, three repeat tracks in the Expedition Fjord region were selected for analysis to determine the difference in elevation between the premelt seasons of 2019 and 2020 as well as one track comparing the premelt and melt seasons of 2019. These elevation differences will be interpolated as accumulation or ablation dependant on the location on the glacier and used to estimate mass balance.

Assessment of groundwater recharge potential in a typical geological transition zone in Bauchi, NE-Nigeria using remote sensing/GIS and MCDA approaches

The increasing demand for water occasioned by harsh climatic conditions, population explosion, and increasing urbanization has necessitated more attention and reliance on groundwater resources, particularly in water-limited regions. Thus, judicious management of available groundwater resources becomes crucial to meet the freshwater requirements in such zones. In this study, remote sensing and geographic information system were deployed to delineate groundwater recharge zones in semi-arid geological transition zones of Bauchi, northeastern Nigeria.Seven thematic layers comprising elevation, slope, land use/land cover, drainage density, lithology, magnetic lineament density, and hydraulic head were integrated based on their degree of influence in groundwater recharge. Normalization of the weights was achieved through the analytical hierarchical process (AHP), while the overall integration of the thematic maps was actualized by overlay analysis in ArcGIS 10.3.1 environment to generate a final groundwater recharge zone map of the area.The resulting map was delineated into three different zones: low, moderate, and high, occupying 20% (627 km2), 77% (2352 km2), and 3% (80 km2) respectively. The overall assessment of recharge zones revealed that a high percentage of the southwestern part of the study are characterized dominantly by poor groundwater recharge potential, attributable to high elevations and impervious rock outcrops with associated steep slopes, thus limited infiltration owing to the high velocity of runoff. The northwestern and parts of the southwestern zones, underlain by migmatite/gneiss, and partly granites, however, exhibited medium-low recharge potential, owing to the occurrence of considerably lower altitudes and occupied by thicker regoliths and underlying rocks of medium-high lineament densities. The sandstones revealed predominantly medium-high recharge potential, attributable to high permeability, lower hydraulic heads, and relatively flat geomorphology which enhances meteoric recharge and base flow processes.

GIS-based vulnerability analysis of the United States to COVID-19 occurrence

The outbreak of COVID-19 in the United States has resulted in over 11.2 million cases and over 240 thousand deaths. COVID-19 has affected the society in unprecedented way with its socioeconomic impact yet to be determined. This study aimed at assessing the vulnerability of the US at the county-level to COVID-19 using the pandemic data from January to June of the year 2020. The study considered the following critical factors: population density, elderly population, racial/ethnic minority population, diabetics, income, and smoking adults. Pearson’s correlation analysis was performed to validate the independence of the factors. Spatial correlations between the COVID-19 occurrence and the factors were examined using Jaccard similarity analysis, which revealed relatively high correlation. A vulnerability to COVID-19 map with a five-level Likert scale was created using Logistic Regression Analysis in ArcGIS. The map showed close agreement in seven representative states, which were selected based on COVID-19 cases including NY, CA, FL, TX, OH, NC, and MT with R2 values between 0.684 and 0.731 with Root Mean Squared Error (RMSE) values between ±0.033 and ±0.057. Furthermore, vulnerability levels from ‘High’ to ‘Very High’ were obtained for the top ten counties with the highest COVID-19 cases with residual values less than or equal to 0.04. The method and resulted vulnerability map can aid in COVID-19 response planning, prevention programs and devising strategies for controlling COVID-19 and similar pandemics in the future.

南四湖流域关键生态系统服务的时空权衡关系

从多尺度科学地研究流域各生态系统服务间的权衡与协同关系，对流域实现经济发展与生态保护双重目标具有重要研究意义。运用InVEST模型模拟评估产水量、水质净化、土壤保持、碳存储、生物多样性维持和授粉等6类区域关键生态系统服务，并通过热点分析、相关分析和主成分分析，定量分析自改革开放以来（1980-2018年）这些生态系统服务的时空变化及其在不同尺度上的权衡关系。结果表明：（1）南四湖流域产水服务呈上升趋势，而水质净化、土壤保持、碳储存、生境质量、授粉等服务则总体呈下降趋势。（2）研究区东部林地和草地广布，是碳存储、生境质量和授粉服务的高值区，而建设用地分布的地区是产水量和土壤保持服务的高值区。（3）产水量与水质净化服务之间呈权衡关系，水质净化与生境质量、碳存储与授粉之间则存在较强的协同关系。（4）在子流域尺度上主要是存在着供给服务（产水量）与调节服务（水质净化和土壤保持）、供给服务（产水量）与支持服务（生境质量）之间的空间权衡关系；在县域尺度上，供给服务、调节服务与支持服务（产水量、水质净化、碳存储、生境质量和授粉）之间主要是空间协同关系，两个尺度之间具有较大差异。研究结果可为管理者在合适的空间尺度上制定相应的政策提供科学支撑，促进南四湖流域生态环境和社会经济协同发展。;It is important to create a win-win situation on both economic development and ecological protection. For better ecological management and protection in the future, it is essential to identify the trade-offs and synergies of multiple ecosystem services (ESs) at differently spatial scales. The relationships of ESs varied over time and spatial scales, it is important to study the spatio-temporal dynamics of relationships to realize the trends of ESs change and determine appropriate scale to manage. However, the spatio-temporal dynamics of ESs relationships in the Chinese large basin remain a challenge, as information on adaptable unit to ESs management is often insufficient. Therefore, the purpose of this research is to identify relationships of ESs on sub-watershed and county scales. Six key ESs in Nansihu Basin were selected to simulate and evaluate by InVEST (Integrated Valuation of Ecosystem Services and Tradeoffs) model since the reform and opening-up (1980-2018), which included water yield (WY), water purification (WP), sediment delivery ratio (SDR), carbon storage (CS), habitat quality (HQ), and crop pollination (CP). In this paper, the spatial distributions of six ESs were analyzed and the hotspots of each ES were identified by hot spot analysis in ArcGIS 10.2. Moreover, the spatial and temporal dynamics of relationships among six ESs were analyzed through correlation and principal component analyses via the correlation and principal component analyses. And further analyses were performed on different scales to the relations. The results displayed as follow:(1) in the Nansi Lake Basin, the WY was increasing from 1980 to 2018, while WP, SDR, CS, HQ and CP were decreasing during this periods. (2) The land use types in eastern basin were mainly forest and grassland, which possessed high levels of CS, HQ and CP. The areas with construction land suggested high levels of WY and SDR. (3) There was a significant trade-off relationship between WY and WP, as well as strongly synergetic relationships between WP and HQ, CS, CP occurred in the basin. (4) There was a great difference in relationships between sub-watershed and county scale. Trade-offs mainly occurred between the provisioning service (such as WY) vs the regulating services (such as WP and SDR) and provisioning service (such as WY) vs the supporting service (such as HQ) on sub-watershed scale. While on the county scale, there was a synergetic relationship between the provisioning service and regulating services vs supporting services (such as WY, WP, CS, HQ, CP). Our research provided an assessment framework to spatio-temporal dynamics of ESs relationships, which suggested that sub-watershed unit was suitable for ecological management. Based on the results of different spatial scales, this research provided scientific support for managers to formulate corresponding strategies at appropriate spatial scale and promote eco-economic coordinated development in the Nansihu Lake Basin.

Pemetaan Daya Dukung Fondasi Dangkal di Wilayah Universitas Jember Berbasis CPT (Cone Penetration Test)

This research aims to make a bearing capacity distribution map of shallow foundations (footplate), which is to provide convenience in terms of examining substructure buildings planned by the consultant by the owner. Spatial concepts method, ArcGIS and kriging, are used to simplify the analysis stage in making bearing capacity maps. Bearing capacity distribution map of soil shows that most of the University of Jember area at two meters depth has hard soil consistency and has a bearing capacity of around 83.9 - 110.9 kg/cm2. The results of comparative analysis of ArcGIS and CPT has a ratio of 0,758 for point 1 and 0,765 for point 2.

Geospatial Modeling of Radon-Prone Areas

Methods for identification of potentially radon-prone areas using geospatial analysis in ArcGIS 10.6 software environment and mathematical modeling in SPSS 19.0 on the example of high background radiation area have been developed. High level of natural radioactivity associated with uranium content in environment objects and natural uranium occurrences, and also the spatial density of faults (reliable and unreliable) and lineaments were taken into account as well as the distance from uranium mine located nearby.
 The method of linear discriminant functions was used to make a math model for determining the level of radon hazard. To do this, data on all locations were divided into training and test samples. Determination of predictors of the mathematical model was performed using Fisher's criterion by their sequential inclusion in discriminant equations. Among the considered 13 factors of radon hazard, seven of them turned out to be informative. For them, canonical coefficients were calculated using the least squares method for first- and second-order polynomials. Based on the values of discriminant functions, a territorial map was constructed to assign the new location to a certain level of radon hazard.
 The maps obtained present the correlation of the radon-prone areas with the zones of high spatial density of faults and lineaments, and confirmed by the data of direct indoor radon measurements. In a limited number of measurements, the methods might get a good help in prioritization for round-the-country radon survey. As far as the model for identification of potentially radon-prone areas is mainly based on geological studies, the further research is supposed to be directed to its approbation for a different geological environment of the Ukrainian shield.

Assessing trends and predicting the cover management factor in a tropical island state using Enhanced Vegetation Index

Soil erosion is a complex process involving multiple factors that contribute to the amount of soil loss. The amount of vegetation cover is one of the main factors used to estimate soil loss and is an important risk factor in informing land use management and soil conservation policies. Cover/crop management (C-factor) is a dynamic soil loss factor and analysing C-factor trends in the context of both space and time, to build a multi-dimensional data structure, increased the value of the trend analysis. The objectives of the study were to (1) utilise EVI dependent static and dynamic predictive equations to compute the C-factor, and (2) to investigate the spatio-temporal changes of the C-factor and hotspots in a tropical small island developing state (SIDS) from 2010 to 2019. ArcGIS Model Builder was utilised to automate the computation of the C-factor using Moderate Resolution Imaging Spectroradiometer (MODIS) Enhanced Vegetation Index (EVI) data and compute the ordinary least square regression. Spatio-temporal analysis was performed using the novel emerging hot spot analysis in ArcGIS to identify statistically significant hot and cold spot trends of cover management to locate new, intensifying, persistent, or sporadic hot spot patterns at different time-step intervals. The regression output for the C-factor and EVI values indicated a strong r2, explaining on average 90% of the models. There was no statistically significant (P value > 0.05) increase in C-factor trend over a 10 year period (2010–2019, P-value = 0.92), a 5 year period (2015–2019; P-value = 0.59), or a 3 year period (2017–2019; P-Value = 0.31). Our results showed that intensifying hot spots (27%) were concentrated along the north–south corridor of the study area, highlighting areas with a statistically significant increase of the C-factor, thus a reduction in vegetation cover over the study period. Integrating spatio-temporal data and spatial technology provided vital cover management estimates for soil practitioners and farmers to guide conservation strategies.

Waste Transportation Route Optimization in Malang using Network Analysis

Malang has a projection population of 861,414 people in 2018. This big population would cause waste generation that is increasing every day. Waste generation was recorded at the amount of up to 646.07 tonnes/day just from Malang in 2018. However, waste transported to landfill was only 516.84 tonnes/day. It means that the load factor was only 84.73%. Waste transportation problems come from various factor. Malang had only 68 temporary waste storage (TPS) that were spread in the city. This number of TPS was not commensurate with waste generation that was generated every day. The limited number of trucks was another issue considering Malang only had 35 trucks capable of making three trips per day. Limited number of trucks and TPS has led to a bad situation for transporting waste. As a result, many wastes were left behind in TPS. Therefore, it is necessary to analyze the best route for the trucks sso that the waste route can be optimized using network analysis in ArcGIS. This study assessed one route of a truck which had the longest distance (TPS Tunggul Wulung) with a total of 60.2 km at a time that it reached in 113.8 minutes. The result of the network analysis method with ArcGIS showed that the total distance declined to 36.2 km. This indicates that the alternative route shown by the shortest distance method has been able to reduce the existing distance for waste transportation route by 24 km. This certainly resulted in the decline in travel time for ± 39 minutes/day. This indicates that the existing routes can be optimized by alternative route network analysis in ArcGIS.

Spatial Analysis to Evaluate Groundwater Vulnerability to Contamination of Unconfined Aquifer in Semarang Lowland Area Using DRASTIC Method

The increasing population up to 1.67% per year in the urban coastal city such as Semarang affects enormous stress on the natural resources – groundwater, in particular. To assess groundwater vulnerability to contamination the DRASTIC method was applied. DRASTIC was one method in compiling a zone of groundwater vulnerability to contamination. This method required seven parameters, namely D (water table depth), R (recharge zone), A (media aquifer), S (soil media), T (topography), I (vadose zone), and C (hydraulic conductivity). Processing of each parameter to calculate the Drastic Index (DI) was developed by using spatial analysis in ArcGIS. The results conduct there is three-level of groundwater vulnerability to contamination namely low, medium, and high. The low vulnerability has the number of DI of 61 to 100, while the DI of moderate is around 101-140. The high level is represented by 141-180 of DI. The low level is distributed in some areas in the south of Semarang, while the medium is dominated in the Ngaliyan area, Gajahmungkur, Semarang Selatan, also found in Tugu, Semarang Barat, Candisari, and some areas in the Semarang Tengah. Indeed, the high level is found in the plains areas in the northern, in the western, and eastern part of Semarang.

Suitability Assessment of the Tools Under a Three-Dimension System of Landscape Monitoring: A Case Study in the NWHS of Bogda

Landscapes provide significant ecosystem service value in Natural World Heritage Sites (NWHSs) and are required to be preserved by regular monitoring and evaluation. It is vital to choose appropriate monitoring tools according to local conditions to guarantee the process is effective and efficient. This study aims to find out the spatial suitability of monitoring tools under a three-dimension system of space-based monitoring, sky-based monitoring, and ground-based monitoring. A suitability assessment was conducted from three aspects—the monitoring environment, object, and effect—from which typical differences existed among the three types of tools. Nine indicators were finalized, in which eight were classified and scored using the Delphi method with objectivity, and the remaining indicator was processed subjectively by quantifying the different monitoring effects on different landscape units by each of the tools. The method was verified using a case study in Bogda of Xinjiang Tianshan through overlay analysis in ArcGIS. The results showed an apparently stepped distribution characteristic related to altitude, where space-based monitoring zones are located in regions of high altitude, and the landscapes in low-altitude regions had the best monitoring effects using the ground-based tool and sky-based tool. Combined with the distribution characteristics of the 3-level protected zones, the results show a consistency with reality and could help planners to strategically deploy monitoring sites and allocate them advisable monitoring facilities and staffing.

Constructing Identities

This book explores the construction of regional identities in the Early Bronze Age through the temporal variation in burial practice in Southwest Norway. Earthen barrows from the regions Etne, Karmøy, Jæren, and Lista are used as the archaeological source for this study. How historically constituted structures together with external practice form part of an open-ended process of identity construction is investigated. Previous research has often used a set, rigid definition of identity, and earthen barrows along the coast of Southwest Norway have therefore frequently been portrayed as part of a southern Scandinavian culture. These perceptions are not necessarily wrong, but neglect the complicated processes that give rise to groups. In this study it is argued that patterns found in the material remains, both unintentional and intentional, express regional variation. Through a quantitative methodology based on a selection of focus points and spatial analysis in ArcGIS the multifaceted process behind identity construction is showcased. As a result, the southwest coast of Norway during the Early Bronze Age can be seen as a more complex and dynamic region. Although many similarities between regions are shared, they are also clearly divided and competitive.

Detection of Environmental Degradation in Jazan Region on the Red Sea, KSA, Using Mathematical Treatments of Remote Sensing Data

Jazan Region subjects mainly to environmental degradation due to anthropogenic activities. In the present study, remote sensing integrated with some mathematical treatments as overlay analysis for adequately evaluating land degradation of Jazan area. The present study focuses on vegetation, geological, urban, and coastal changes. Three satellite images were acquired for typically assessing these changes in 2008, 2014, and 2018. To detect the environmental degradation, normalized difference vegetation index (NDVI) and statistical model were used for vegetation, principal component analysis (PCA) and band ratios (b5/b7 and b3/bl) for geological changes, and normalized difference built index (NDBI) for urban degradation. Also, coastal changes had been detected using some analysis of ARCGIS. Results showed that NDVI in 2008, 2014, and 2018 were 5.7, 11, and 7.2%, respectively. From the linear model and statistical analysis of vegetation in the future, there is unaccountable disappearance of the vegetation by the end of 2020 with the disappearance of the evergreen areas of trees and desert plants around region. For geological changes, PCA of the three images give more than 80% of geological features of the study area. Band ratios, b5/b7 and b3/bl, emphasize alteration, clay, and Fe minerals that have specific spectral reflectance and absorption features in these bands. For coastal changes, the reasonable rate of beach growth was precisely 85.3% between 2008 and 2014, while this ratio positively declined to 14.7% between 2014 and 2018 of the economic expansion during the monitoring period from 2008 to 2018. Urban area of Jazan City was 262.34, 354.43, and 409.17 km2 for 2008, 2014, and 2018, respectively. Results showed that urban area has been increased from 2008 to 2018 with a percentage of 55.9%. The marked degradation may be reasonably anticipated to anthropogenic activities and unplanned management. Technology date should be applied universally to avoid environmental degradation of Jazan Region. Remote sensing and statistical model might offer an effective and good assessment of land degradation.

Identification of groundwater potential zones in the hard and soft rock terrains of Kogi State, North Central Nigeria: an integrated GIS and remote sensing techniques

The availability of groundwater varies from region to region, place to place, sometimes within a few meters and even within the same geological formation. In the study area, an integration of various thematic maps such as geomorphologic, slope, drainage density, land use/land cover maps derived from remote sensing images, geological and lineament density maps and soil map helped in generation of groundwater potential zone map using the weighted overlay analysis in ArcGIS by assigning suitable weights on the Saaty’s scale according to their importance in occurrence of groundwater. However, the assigned weights of the thematic layers and their features were then normalized by using AHP. The groundwater potential zones in the study area were grouped into four classes, and their distributions are: excellent (10.23%), good (51.35%), moderate (34.26%) and poor (4.16%). Excellent groundwater prospect map which covered only 10.23% of the study area falls within the lowlands and plains. For the accuracy of the groundwater potential zone map of the study area based on RS and GIS-based model, it was validated with the data on existing boreholes which was collated for 60 boreholes in the study area and shows positive correlation.

Land use and forest cover dynamics in the North-eastern Addis Ababa, central highlands of Ethiopia

BackgroundThe Ethiopian highlands have experienced intense levels of land use dynamics and forest cover transformations over the past few decades. Multiple socio-economic, demographic and bio-physical factors have driven such transformations. Nevertheless, recent expansion of urban settlements and infrastructural development could have accelerated the rate at which land cover transformations preceded but little is known about their impacts on land cover transformations in the vicinity of Addis Ababa, Ethiopia. This study, therefore, focuses on detecting long term dynamics of land use/land cover (LULC) change since the 1950s and current state of forest susceptibility to degradation in North-eastern Addis Ababa, Ethiopia. In this study Panchromatic Aerial photographs (1957), MSS (1975), TM (1995) and Sentinel-2 (2017) images were used to generate LULC types. We employed object-based classification techniques to generate LULC types for 1957 aerial photographs and maximum likelihood algorithm for images of 1975, 1995 and 2017. We also generated forest degradation susceptibility map for the study area by employing a multi-criteria approach on the ArcGIS analysis platform.ResultsOver the course of 60 years (1957–2017) the extent and direction of LULC have become more dynamic. Agricultural land and forest land showed a comparably equal extent of net change (+ 36.7% and − 37.8%, respectively) but to opposite directions. Forest lost 25.1% and 18.7% of its cover to barren land and agricultural land, respectively. The net change for forest was negative except for the period 1975–1995, with varying rates of deforestation during the four distinct study periods. However, a heightened level of deforestation occurred after the mid-1990s due to rapid urban growth and a change in government economic policy. A 6.2% net change of urban/settlement served as a catalyst for LULC transformations in the last two decades. Our findings also revealed that 97.2% of forests were located at a radius of 1 km distance from urban centers and settlements whereas 92% of them were accessible by road networks of a km radius. Similarly, 71% of forests suffer from edge effects while biophysical factors such as streams as vectors of disturbance and slopes expose about 35% of forests to degradation.ConclusionOver the last six decades the study area has shown an unprecedented level of LULC change. The main drivers of change were the combination of bio-physical processes especially drought cycles, demographic dynamics (population growth, density and internal migration), urbanization and successive government development policies. The massive conversion of forests to agricultural land and barren land in the study area will have far reaching impact on biodiversity and ecosystem services, land degradation and a change in local hydrological regime.

Assessment of air pollution and health hazard associated with sawmill and municipal waste burning in Abeokuta Metropolis, Nigeria.

Indiscriminate disposal and open burning of sawmill and municipal solid wastes constitute hazards to the quality of the immediate environment and human health. This study assessed the levels of pollutants emitted by burning sawmill and municipal wastes, and their potential hazards. Nine selected sawmills and 6 municipal solid-waste dumps in Abeokuta metropolis were investigated. During waste burning, the concentrations of NO2, SO2, CO, H2S, NH3 and VOC were monitored in replicates at the dumpsites, 10m, 20m and the nearest houses using portable samplers (Aeroqual and Multi-RAE). Mean, ANOVA, correlation and regression statistical tools were used to analyse air quality data; air quality index (AQI) was employed to classify the hazard rating of the gaseous pollutants. Nearest neighbour analysis in ArcGIS 10.0 was used to investigate dumpsites location pattern within the city. The concentrations (mg/m3) of sampled parameters from source to nearest house (NH) at the dumpsites ranged as follows: < 0.002-0.175 (NO2), < 0.002-0.235 (SO2), 0.065-0.425 (H2S), 13.98-47.40 (CO), 6.74-170.41 (NH3) and 31.13-820.03 (VOC) in wet and dry seasons. The mean concentrations of NO2, SO2 and VOC were below permissible limits at most locations while CO values were higher at all dumpsite. Significant variations (p < 0.05) were observed in the concentrations of the monitored parameters except NO2 values (SMW) in dry season. AQI rated NO2 and SO2 concentrations as "good" at all sites while CO emission ranged from unhealthy to hazardous across the dumpsites. In conclusion, the present locations of SMW and MSW dumps in the city degrade environmental quality and are unsafe for human health.

天津滨海新区湿地景观连接度距离阈值研究

PDF HTML阅读 XML下载 导出引用 引用提醒 天津滨海新区湿地景观连接度距离阈值研究 DOI: 10.5846/stxb201804190897 作者: 作者单位: 南开大学环境科学与工程学院,天津师范大学城市与环境科学学院,南开大学环境科学与工程学院 作者简介: 通讯作者: 中图分类号: 基金项目: 天津市自然科学基金科技特派员项目（16JCTPJC53900） Distance thresholds of wetland landscape connectivity in Tianjin Binhai New Area Author: Affiliation: College of Environmental Science and Engineering, Nankai University,,College of Environmental Science and Engineering, Nankai University Fund Project: Science and technology special project of Tianjin Natural Science Foundation 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:在应用景观连接度研究景观格局变化时，选择适宜的距离阈值是关键。适宜的距离阈值有利于识别景观中的关键斑块并及时发现连接脆弱的区域，对景观格局动态分析、生态恢复研究等均具有重要意义。以天津市滨海新区湿地生态系统为研究对象，将研究区域划分为不同的焦点景观，焦点景观是依据研究区域栖息候鸟的生境面积而划分的面积大小相同的区域，并通过ArcGIS中的泰森多边形分析实现，焦点景观分析可为面积更大、结构更加复杂的景观分析提供新的思路。文章选取斑块间链接数（NL）、组分数（NC）、等效连接面积指数（ECA）、景观巧合概率指数（LCP）来表征景观连接度，设定100、200、400、600、800、1000、1500、2000、3000、5000、8000 m共11个距离阈值，探讨不同距离阈值下各指数的变化规律，对比分析研究区域整体景观斑块和焦点景观内各斑块的连接度指数随距离阈值变化的异同，最终确定研究区域最佳距离阈值。结果表明：（1）各焦点景观内斑块的景观连接度指数随距离阈值的变化趋势与研究区域整体景观斑块相似且对应的最佳距离阈值相同；（2）天津市滨海新区湿地景观连接度距离阈值的适宜范围是400-800 m，该区间内进行景观格局分析研究能够较为真实的反映出研究区域实际景观状况；（3）通过进一步研究，最终确定400 m为天津滨海新区湿地景观连接度最佳距离阈值。研究结果可为天津市滨海新区湿地景观研究提供参考，在实际研究中距离阈值的选择可根据具体研究目标、研究层次需求等进行适当调整。 Abstract:When applying landscape connectivity to the study of landscape pattern changes, it is important to choose the appropriate distance threshold, which affects the analysis of landscape connectivity in the study area. If the distance threshold is set too low, the patches in the area will remain unconnected, and fragmentation will be severe, whereas if the distance threshold is set too high, the patches in the area are interconnected and grouped together. However, neither of these scenarios is likely to truly reflect the actual condition of the landscape in the study area. Using an appropriate distance threshold will facilitate the identification of key patches in the landscape and the discovery of vulnerable areas, both of which are important for the dynamic analysis of landscape patterns and ecological restoration studies. The present study investigated this principle using Landsat 8-OLI remote sensing images of a wetland ecosystem of the Tianjin Binhai New Area, taken on April 14, 2017. The research area was divided into different focal landscapes, in order to prevent software stalling and reductions in data processing speed that could have resulted from the large study area and provide a new analytical idea for this field. The focal landscape was the same size area, based on the habitat area of the migratory birds in the study area, and was analysed by Thiessen polygon analysis in ArcGIS. The number of links, number of components, equivalent connectivity area, and landscape coincidence probability were selected to characterize the landscape connectivity, and a total of 11 distance thresholds (100, 200, 400, 600, 800, 1000, 1500, 2000, 3000, 5000, and 8000 m) were selected to draw the ‘Landscape Connectivity Index-Distance Threshold’ curve, which was used to study the trend of each index under different distance thresholds. By comparing the overall landscape patch and the focal landscape connectivity index with distance thresholds, the optimal distance threshold for the study area was determined. (1) The optimal distance thresholds selected by the two methods of focal landscape and overall landscape patch were the same, and the proposed method provides new ideas for future regional landscape analysis and more complex ecological landscape pattern research. (2) The range of 400-800 m can be used as suitable distance threshold ranges for the dynamic change of landscape pattern and restoration of ecosystems in the Binhai New Area. In this interval, the connectivity of the habitat patch in the study area was relatively stable, which clearly illustrates the distribution of the patches and helps to identify the important patches in the landscape. (3) Through further research, 400 m was finally selected as the optimal distance threshold for the connectivity of the wetland ecosystem in Tianjin Binhai New Area. These findings provide a reference for studying wetland landscapes in the Tianjin Binhai New Area. In addition, the selection of the distance threshold in practical research can be adjusted according to specific research objectives and research level requirements. 参考文献 相似文献 引证文献