Spatial Analysis of Artisanal and Small-Scale Mining in the Tarkwa-Nsuaem Municipality of Ghana

Abstract In recent times there have been lots of public outcry on the environmental and public health and safety effects of Artisanal and Small-scale gold Mining (ASM) and the need to monitor ASM activities for reclamation purposes. To effectively develop and deploy policy responses to the environmental and human health effects of ASM, knowledge of the locations and distribution of ASM sites is a prerequisite. However, information regarding ASM hotspots and spatial distribution, the scope and types of ASM operations are hard to find. Therefore, this research was designed to use satellite-based data to map out ASM sites, focusing on the Tarkwa-Nsuaem municipality as the study area. Several image processing techniques were applied on a Landsat 8 satellite image downloaded from the US Geological Survey website. The image processing resulted in the identification of 221 clusters of ASM sites, representing 12.72% of the total size of the study area. To further explore the effects of these ASM sites, Areas of Interest (AOI) including forest reserve, rivers, large-scale mines and urban settlements were defined. By selecting and analysing the location and distribution of the ASM sites in relations to the AOI, the study was effective in identifying environmentally sensitive and critical areas warranting the urgent attention of society to mitigate the health, safety and ecosystem service effects of ASM in the study area. By identifying the environmental sensitive areas being affected by ASM, the findings could support the prioritisation of reclamation efforts.   Keywords: Artisanal Small-Scale Mining, Satellite Image, Environmental Effect, Public Health and Safet

Ramification of Datum and Ellipsoidal Parameters on Post Processed Differential Global Positioning System (DGPS) Data – A Case Study

The World Geodetic System 1984 (WGS 84) is the global reference frame upon which Global Positioning System (GPS) observations are referenced to. Observations in the frame are in latitudes, longitudes and ellipsoidal heights. For use in a particular locality, it is necessary to convert these into the local coordinate system. In Ghana, the datum and ellipsoidal parameters for Ghana War Office and Clarke 1880 are used for the transformation of the GPS coordinates from the WGS 84 datum system to the Ghana National Grid System. This paper therefore examines post processed DGPS data using these two datum and ellipsoidal definitions separately. Dual frequency DGPS data were collected from 19 survey pillars (ie SGW D224/14/1 to SGW D224/14/19) and post processed using Clarke 1880 datum and ellipsoidal parameters. The raw data was also post processed using Ghana War Office datum and ellipsoidal parameters. The results for the two indicated an average difference of 7.23 m (23.72 ft) for 19 stations. This certainly does not fall within the tolerance set by Survey and Mapping Division (SMD) of the Lands Commission for cadastral plans production, which is +/- 0.9114 m (+/-3 ft). A composite plan using the post processed data from the two datum and ellipsoidal definitions was produced. The plan shows an overlapping area by the use of the two coordinates to plot, an indication of a potential conflict between ownership on paper which may not necessary exist on the ground.Keywords: Differential, Global Positioning System, Datum and Ellipsoidal Parameter

The use of gis to study the spatial variation of diseases: a case of western region, Ghana

The ability to formulate disease control programmes and put strategic action plans into practice has become an important issue for Regional Health Directorates in Ghana. An important factor in disease control programmes is to correlate variations in different communities with environmental factors using spatially reliable data. To achieve this, spatial distribution maps for predominant diseases such as malaria, skin infection, Respiratory Tract Infection (RTI), asthma and diarrhea for the year 2005 were created. In this study, a database of disease statistics and the geographical information representing the boundaries as well as the centre of the administrative units of the Western Region of Ghana were built using cartographic and GIS techniques – choropleth mapping to examine the spatial distribution of the selected diseases. The results show that there is a strong correlation between mining activities and the prevalence of diseases under study in the Western Region

A 3D Procrustean Approach to Transform WGS84 Coordinates to Ghana War Office 1926 Reference Datum

Abstract Satellite positioning technique such as Global Positioning System (GPS) is available to all countries for geospatial positioning. The availability of such positioning technique has revolutionised surveying in Ghana. The GPS operates on a global reference frame to fix control points for surveying and mapping purposes. There is therefore the need to transform coordinates from the satellite-based datum to the Ghana War Office 1926 datum. Several iterative methods have been proposed over the years for coordinate transformation and have been found to exhibit good transformation accuracy. However, these iterative methods always demand the linearisation of the transformation model equations and initial approximation values of the yet to be determined transformation parameters. These computational processes further enhance the computational complexity of the iterative methods and longer convergence time. As alternative solution, the Procrustes method has been proposed and applied to solve coordinate transformation problems in different geodetic reference networks. Review of previous studies indicates that the Procrustes method is direct, simple to use and produce satisfactory transformation accuracy. This method, however, is yet to be applied to ascertain its efficiency in the Ghana geodetic reference network. Therefore, this study utilised the 3D Procrustean approach to transform coordinates from World Geodetic System 1984 (WGS84) to Ghana War Office 1926 reference datum. The technique produced Root Mean Square Horizontal Error (RMSHE), Arithmetic Mean of the Horizontal Error (AMHE) and Standard Deviation (SD) values of 1.003 m, 0.901 m and 0.452 m, respectively. This study is serving as an extension to the ongoing research works to determine optimal transformation model for Ghana geodetic reference network.   Keywords: Procrustean Approach, Coordinate Transformation, Conformal Model, Satellite Positionin

Analysis of Methods for Ellipsoidal Height Estimation – The Case of a Local Geodetic Reference Network

Ghana’s local geodetic reference network is based on the War Office 1926 ellipsoid with data in latitude, longitude and orthometric height  without the existence of ellipsoidal height. This situation makes it difficult to apply the standard forward transformation equation for direct conversion of curvilinear geodetic coordinates to its associated cartesian coordinates (X, Y, Z) in the Ghana local geodetic reference network. In order to overcome such a challenge, researchers resort to various techniques to obtain the ellipsoidal height for a local geodetic network. Therefore, this paper evaluates, compares, and discusses different methods for estimating ellipsoidal height for a local geodetic network. The investigated methods are the Abridged Molodensky transformation model, Earth Gravitational Model, and the Orthometric Height approach. To evaluate these methods, their estimated local ellipsoidal height values were implemented in the seven-parameter similarity transformation model of Bursa-Wolf. The performance of each of the methods was assessed based on statistical indicators of Mean Square Error (MSE), Mean Absolute Error (MAE), Horizontal Position Error (HE) and Standard Deviation (SD). The statistical findings revealed that, the Abridged Molodensky model produced more reliable transformation results compared with the other methods. It can be concluded that for Ghana’s local geodetic network, the most practicable method for estimating ellipsoidal height is the Abridged Molodensky transformation model.  Keywords: Abridged Molodensky Model, Earth Gravitational Model, Orthometric Height, Geodetic Networ

A Spatio-Temporal Based Estimation of Sequestered Carbon in the Tarkwa Mining Area of Ghana

The vegetation in the Tarkwa Mining Area (TMA) has experienced changes as a result of population growth, urbanization, mining activities and illegal chainsaw operations and this has led to an increase in temperature over the past years. Therefore, studying its forest biomass carbon (C) stock and its spatio-temporal change is important to the sustainability of forest resources and understanding of the forest C budget in the TMA. In this study, aboveground forest biomass/carbon stock and its changes in the TMA were estimated from three nested-circular plots of horizontal radii 12.62 m, 8 m and 4 m using stratified random sampling from sixty locations in five land use/cover types as well as GIS/Remote Sensing techniques over a 21 year period. An estimated total of 1 250.93 ± 7 Mg/km2 carbon was recorded in the TMA. Carbon in different land-use/cover types ranges from 587.76 ± 4 Mg/km2 carbon in closed canopy to 270.23 ± 2 Mg/km2 carbon in shrubs/herbaceous. The TMA also experienced an average of 412.14 Gg of carbon (equivalent to 19.63 Gg carbon per year) lost between 1986 and 2007 due to the changes in the land use/cover types. The study area is however, considered a net source of carbon.Keywords: Spatio-Temporal, Carbon, Mining, Biomass, GI

Modelling of Malaria Risk Areas in Ghana by using Environmental and Anthropogenic Variables – A Spatial Multi- Criteria Approach

Malaria is the leading cause of morbidity and mortality in Ghana, accounting for over three million cases and thousands of deaths annually. The risks of morbidity and mortality associated with malaria are characterized by spatial and temporal variation across the country. This research sought to use GIS and multi-criteria decision analysis to produce a predictive model of malaria using eight risk factors ranging from environmental to anthropogenic. Each of the risk factors was classified into three classes of malaria risk according to how it impacts malaria prevalence. The classified risk factors were finally overlaid through the use of weighted overlay after weights were determined from them using the Analytical Hierarchy Process (AHP). Results indicate that high risk areas are concentrated at the central as well as the west-southern parts of the country consisting mainly of the Ashanti, Brong Ahafo, Eastern, Central and the Western Regions. No area was classified as low risk while 53.51% and 46.49% were classified as medium and high risk respectively. The risk map created can serve not only as a predictive tool, but can be used to obtain a comprehensive understanding of the dynamics of malariatransmission.Keywords: Malaria, GIS, Analytical Hierarchy Process, Weighted Overla

Ambient particulate matter air pollution and stillbirth in Ghana: A difference-in-differences approach

Sub-Saharan African countries, including Ghana, are known hotspots for fine particulate matter air pollution (PM2.5) and stillbirths but lacked epidemiologic evidence. We investigated the association between PM2.5 and stillbirth in Ghana. District-level stillbirth data were obtained from the Ghana Health Service for all 260 local districts from 2012 to 2019 for a total of 5,229,338 births, including 81,611 stillbirths. Spatiotemporal datasets, including satellite-derived PM2.5, temperature, population density, and gross domestic product were linked with the birth data. We applied a variant difference-in-differences design with conditional quasi-Poisson regression to estimate the risk of stillbirth associated with annual PM2.5 concentrations. We adjusted for relevant environmental and sociodemographic factors and performed subgroup analyses by population density and household air pollution. The average district-level annual stillbirth incidence was 29 (standard deviation = 55) per 1000 births. The annual average PM2.5 concentration was 59.97 μg/m3 (standard deviation = 9.75). Every 10 μg/m3 increment in annual average PM2.5 was associated with a 3% risk of stillbirth (RR); 1.03 (95% CI: 0.97, 1.09) for allsource PM2.5 and 2% risk each for anthropogenic (RR = 1.02, 95% CI: 0.96, 1.07) and natural (RR = 1.02, 95% CI: 0.94, 1.11) sources. The association was higher for moderate or high subgroup, relative to low subgroup and higher in natural than anthropogenic sources of PM2.5 exposures. Thus, there was some evidence for an adverse association between PM2.5 exposure and stillbirth but estimates were less precise. Given that the district-level variation may be underpowered, stronger risk is expected in future high-quality individual-level longitudinal cohort studies in Ghana.Sylvester Dodzi Nyadanu, Gizachew Assefa Tessema, Ben Mullins, Bernard Kumi-Boateng, Anthony Adofo Ofosu, Gavin Pereir

Ambient air pollution, extreme temperatures and birth outcomes: a protocol for an umbrella review, systematic review and meta-analysis

Prenatal exposure to ambient air pollution and extreme temperatures are among the major risk factors of adverse birth outcomes and with potential long-term effects during the life course. Although low- and middle-income countries (LMICs) are most vulnerable, there is limited synthesis of evidence in such settings. This document describes a protocol for both an umbrella review (Systematic Review 1) and a focused systematic review and meta-analysis of studies from LMICs (Systematic Review 2). We will search from start date of each database to present, six major academic databases (PubMed, CINAHL, Scopus, MEDLINE/Ovid, EMBASE/Ovid and Web of Science Core Collection), systematic reviews repositories and references of eligible studies. Additional searches in grey literature will also be conducted. Eligibility criteria include studies of pregnant women exposed to ambient air pollutants and/or extreme temperatures during pregnancy with and without adverse birth outcomes. The umbrella review (Systematic Review 1) will include only previous systematic reviews while Systematic Review 2 will include quantitative observational studies in LMICs. Searches will be restricted to English language using comprehensive search terms to consecutively screen the titles, abstracts and full-texts to select eligible studies. Two independent authors will conduct the study screening and selection, risk of bias assessment and data extraction using JBI SUMARI web-based software. Narrative and semi-quantitative syntheses will be employed for the Systematic Review 1. For Systematic Review 2, we will perform meta-analysis with two alternative meta-analytical methods (quality effect and inverse variance heterogeneity) as well as the classic random effect model. If meta-analysis is infeasible, narrative synthesis will be presented. Confidence in cumulative evidence and the strength of the evidence will be assessed. This protocol is registered with PROSPERO (CRD42020200387).Sylvester Dodzi Nyadanu, Gizachew Assefa Tessema, Ben Mullins, Bernard Kumi-Boateng, Michelle Lee Bell and Gavin Pereir

Prenatal exposure to long-term heat stress and stillbirth in Ghana: A within-space time-series analysis

Introduction: Few studies examined the association between prenatal long-term ambient temperature exposure and stillbirth and fewer still from developing countries. Rather than ambient temperature, we used a human thermophysiological index, Universal Thermal Climate Index (UTCI) to investigate the role of long-term heat stress exposure on stillbirth in Ghana. Methods: District-level monthly UTCI was linked with 90,532 stillbirths of 5,961,328 births across all 260 local districts between 1st January 2012 and 31st December 2020. A within-space time-series design was applied with distributed lag nonlinear models and conditional quasi-Poisson regression. Results: The mean (28.5 ± 2.1 °C) and median UTCI (28.8 °C) indicated moderate heat stress. The Relative Risks (RRs) and 95% Confidence Intervals (CIs) for exposure to lower-moderate heat (1st to 25th percentiles of UTCI) and strong heat (99th percentile) stresses showed lower risks, relative to the median UTCI. The higher-moderate heat stress exposures (75th and 90th percentiles) showed greater risks which increased with the duration of heat stress exposures and were stronger in the 90th percentile. The risk ranged from 2% (RR = 1.02, 95% CI 0.99, 1.05) to 18% (RR = 1.18, 95% CI 1.02, 1.36) for the 90th percentile, relative to the median UTCI. Assuming causality, 19 (95% CI 3, 37) and 27 (95% CI 3, 54) excess stillbirths per 10,000 births were attributable to long-term exposure to the 90th percentile relative to median UTCI for the past six and nine months, respectively. Districts with low population density, low gross domestic product, and low air pollution which collectively defined rural districts were at higher risk as compared to those in the high level (urban districts). Discussion: Maternal exposure to long-term heat stress was associated with a greater risk of stillbirth. Climate change-resilient interventional measures to reduce maternal exposure to heat stress, particularly in rural areas may help lower the risk of stillbirth