World Geodetic System Research Articles

Priority Analysis of Mangrove Guraping Ecotourism Development Based on Spatial Data Using Process Hierarchy Analysis

This article aims to analyze the development priorities of Guraping mangrove ecotourism based on spatial data using process hierarchy analysis (AHP). The research process is divided into three stages: the pre-processing stage, processing stage, analyzing and reporting phase. In the processing stage, the spatial data used is Landsat 8 OLI in the Guraping mangrove ecotourism area from 2013-2021 with the Coordinate Reference System World Geodetic System (WGS) 84 or Universal Transverse Mercator (UTM) Zone 52N. In the Processing stage, raster data for each zone in the Guraping mangrove ecotourism area will be calculated using the Normalized Difference Vegetation Index (NDVI) algorithm to determine the maximum, average, and minimum values value. The analyzing and reporting phase contains an idea of NDVI calculations result related to the Decree of the Minister of State for the environment in 2004. The findings of this study indicate that the ranking system in the Analytical Hierarchy Process (AHP) algorithm can be used to analyze the priority of the Guraping mangrove ecotourism development program. In AHP Calculation, the programs consist of rehabilitation, restoration, reclamation, and conservation. In addition, the alternatives are zone 1, zone 2, and zone 3. The ranking results show that the program relevant to the NDVI calculation of the Guraping mangrove ecotourism context is the rehabilitation program. Furthermore, the alternative ranking results show that Zone 1 is the priority zone for the rehabilitation program.

A Review of Termite Species and Their Distribution in Thailand.

Simple SummaryThere is little information available on termite species in Thailand. We reviewed termite species and information on their distribution in Thailand via the Google Scholar search platform and online databases with the QGIS program to create a map of termite species. In total, 44 coordinates were obtained from 19 reviewed sources, with approximately 75 species of termites identified at the species level and 83 unknown species of termites being reported across all regions.Although 3105 termite species have been documented worldwide, little information is available on those in Thailand. In this review, the Google Scholar search platform and the Scopus and Science Direct databases were used to obtain information on termite species and for georeferencing. The QGIS software was used to create point localities that were overlaid on the Thailand administrative level 1 (province) to map the distribution of termite species in the country based on the World Geodetic System 1984. From the 19 reviewed sources, 44 defined coordinates were identified in 14 provinces across Thailand. Among these 44 coordinates, we found 75 termite species and 83 unknown species of termites; in total, 36 termite species were from the North (6 locations), 33 species were from the Northeast (10 locations), 34 species were from the West (4 locations), 29 species were from the Central region (3 locations), 44 species were from the East (8 locations), and 54 species were from the South (13 locations). The most predominant species in all regions were Globitermes sulphureus, Macrotermes gilvus, Microcerotermes crassus, and Microtermes obesi.

ASSESSMENT OF AFFORESTATION PROGRAMME AND COMMUNITY PERCEPTION IN GUMEL LOCAL GOVERNMENT AREA, JIGAWA STATE

This study assessed afforestation programme and community perception in Gumel Local Government area of Jigawa state. Field data collection was done using structured questionnaire and Landsat satellite imageries. A total of two hundred (200) questionnaire were distributed to the 200 sample size drawn from the sample area using a multi-stage sampling design technique. In a similar way, Landsat data were collected for a period of thirty (30) years using Landsat TM for 1988 and 1998 with Landsat ETM for 2008 and landsat-8 operational land imager (OLI) for 2018 using Earthexplorer. A 30m by 30m resolution Landsat image of the study area was obtained from NASA website. The images were downloaded from the Global Land Cover Facility of the University of Maryland (GLCF, 2018) and the United States Geological Survey (USGS) and spatially referenced in the Universal Transverse Mercator (UTM) projection with datum World Geodetic System (WGS). The images were extracted to Tiff formats for processing and classification using maximum likelihood classifier in Idrisi Selva. The collected data were subjected to analysis such as mean, simple percentage, graphs and tables. Results shows that between the year 1988 to 2018, afforestation in Gumel Local Government Area of Jigawa State increases significantly due to the success of the afforestation programme. It was however recommended that Government agencies in charge of forestry activity are thereby encouraged to put up measures in ensuring the avoidance of forest encroachment activities so as to ensure abundance trees and land covers.

İnsanız Hava Aracı (Drone) ile Erozyon Alanlarının Tespiti: Trakya Yarımadası Örneği

Bu çalışma, Trakya Yarımadası’nda tespit edilen erozyon bölgelerinin alan ve hacimlerinin Coğrafi Bilgi Sistemleri (CBS) kullanılarak hesaplanması amacı ile gerçekleştirilmiştir. Uzaktan algılama ile yapılan ölçümler hem zaman kazanımı hem de fazla işgücünün önüne geçmektedir. Ayrıca drone ile çekim yapılabilecek araziler için satın alınabilecek uydu görüntülerinden daha az maliyetli olmaktadır. Bu amaçla, bölgede doğal karakteristikleri farklılık gösteren 13 erozyon alanı incelenmiş ve insansız hava aracı (drone) ile görüntüler elde edilmiştir. Çalışmada İHA verilerinin kalibrasyonu amacıyla sınırları belli olan ve doğaya zarar vermeyen beyaz boya ile sınırları belirlenmiş ve çeşitli yüksekliklerden bu alanların tüm ölçümleri (uzunluklar, açılar vb.) yapılmıştır. Sınırları belirlenen alanlar daha sonra İHA görüntüleri alınarak CBS yazılımları ve grafik programı “Autodesk Inventor” ile çeşitli proseslerden geçirilerek hacim hesaplaması yapılmıştır. Görüntülerde farklılık olmaması için uygun hava koşulları beklenmiş ve birleştirilecek olan İHA görüntüleri benzer hava şartlarında elde edilmiştir. Farklı hava koşullarında alınan görüntülerin birleştirilmesinde ışık, gölge gibi faktörlerin hesaplamalarda herhangi bir sapmaya neden olmaması ve görsel olarak farklılık oluşturmaması için özen gösterilmiştir. Toplam 13 adet erozyon alanlarından görüntüler alınmış ve çalışmada koordinat sistemi olarak WGS 1984 (World Geodetic System 1984) kullanılmıştır.
 Bu görüntüler birleştirilerek bu alanların ortomozaik görüntüleri oluşturulmuştur. Görüntülerdeki bölgelerin alan ve hacimlerinin yanı sıra kalibrasyonları da yapılmıştır. Yapılan çalışmada, kalibrasyon için küçük bir alanın kullanılması alansal hesaplamada doğruluk oranını %90’ın üzerine çıkarırken hacim ölçümlerinde ise bu oran uçuş yüksekliğine göre %60 – 78 arasında bulunmuştur. 
 Yaklaşık 100 m2 alanda yapılan kalibrasyon çalışmasında 100 metre yükseklikten çekilen görüntüde 12 fotoğraf, 10 metre yükseklikten çekilen görüntüde ise 103 fotoğraf kullanılmıştır. Buna göre, yerden 10 metre yükseklikten çekilen görüntüde hacimsel doğruluk oranı %78,57 bulunmuştur.

What was the River Ister in the Time of Strabo? A Mathematical Approach

Abstract We introduce a novel method for map registration and apply it to transformation of the river Ister from Strabo’s map of the World to the current map in the World Geodetic System. This transformation leads to the surprising but convincing result that Strabo’s river Ister best coincides with the nowadays Tauernbach-Isel-Drava-Danube course and not with the Danube river what is commonly assumed. Such a result is supported by carefully designed mathematical measurements and it resolves all related controversies otherwise appearing in understanding and translation of Strabo’s original text. Based on this result, we also show that Strabo’s Suevi in the Hercynian Forest corresponds to the Slavic people in the Carpathian-Alpine basin and thus that the compact Slavic settlement was there already at the beginning of the first millennium AD.

Comparative Analysis of the Molodensky and Kotsakis Ellipsoidal Heights Transformation between Geocentric and Non-Geocentric Datums Models

The non-availability of ellipsoidal heights of local geodetic Datums has made it necessary for the application of ellipsoidal heights transformation models to the available global ellipsoidal heights to obtain their respective theoretical heights in local Datums. It is required to know the accuracy, as well as reliability of any model of interest before its application. For that reason, this study comparatively analyses the Molodensky and Kotsakis models for the transformation of ellipsoidal heights between geocentric and non-geocentric Datums to determine the reliability of the Kotsakis model. The Global Navigation Satellite System (GNSS) data of the used stations were processed in World Geodetic System 1984 (WGS84) datum to obtain their global geographic coordinates and ellipsoidal heights. The coordinates, ellipsoidal heights and the transformation parameters between WGS84 and Minna Datums were applied to the Molodensky and Kotsakis models to compute the Clarke 1880 theoretical heights of the stations. The Molodensky model was used as a reference to which the Kotsakis model ellipsoidal heights were compared to obtain the Kotsakis model ellipsoidal heights discrepancies, as well as residuals. The residuals were used to compute the Root Mean Square Error (RMSE) of the Kotsakis model. The computed RMSE, as well as reliability of the model is 1.244 m. The study concluded that the low reliability, as well as accuracy of the Kotsakis model might be as a result of the two rotation datum shift parameters in it as they are the main differences between the two models.

Uzbekistan's coordinate system transformation from CS42 to WGS84 using distortion grid model

Currently, a non-geocentric geodetic coordinate system introduced in 1942 (CS42), based on the Krasovsky ellipsoid and the Baltic system of normal heights introduced in 1977, is used for geodetic works in the Republic of Uzbekistan. The development of the GNSS network proposes a task of transition to a new geocentric system based on the World Geodetic System 1984 (WGS84) ellipsoid. Many software products adopt 3- or 7-parameter conversions, which can cause errors up to several meters and are not suitable for many applications. In this case, local transformations using a grid of differences between observation points with known coordinates in both datums would give the best accuracy. In this paper, we discuss various interpolation methods (Kriging, Minimum Curvature, Inverse Distance to a Power and Radial Basis Function) to solve the distortion modeling between CS42 and WGS84 systems for national datum improvement. The results show that the distortion models share a common tendency for all interpolation methods: the maximum horizontal displacements are concentrated along the West Tien Shan lineament, which is the boundary of the relief lowering. The discrepancies between the grid-based (calculated) and GPS-measured coordinates are evaluated. Statistical and spatial analysis has confirmed that for the coordinate transformation from CS42 to WGS84 and vice versa, grid-based transformation with Radial Basis Function interpolation has a high accuracy transformation. Analysis of the available data across the eastern part of the country shows that some positional distortions existed between the CS42 and WGS84 datums. For the best RBF method, the magnitude of these distortions is about 0.019–0.755 m with a standard deviation of 0.015 m.

The potential study of marine aquaculture location in Eastern Bintan Island

Bintan is one of Indonesia’s islands, consisting of nearly 2408 small islands and directly adjacent to Singapore and Malaysia. The strategic geographic location and many small islands and supported by 95% of the sea area give Bintan Island an advantage in developing the marine aquaculture sector. This study aims to apply remote sensing analysis to collect comprehensive information on the strategic Marine Aquaculture Zone (MAZ) in the eastern part of Bintan Island. The data used in this study were the concentration of chlorophyll-a (Chl-a) and Sea Surface Temperature (SST) from MODIS level-3 with a resolution of 4 km from January to December 2019. The pre-processing data analysis on SST and Chl-a concentrations was used SeaDas software to ensure the results of the data projections in the form of the World Geodetic System 84 (WGS84) format. The data processing stage uses ER Mapper software to project the SST distribution and Chl-a concentration into a contour. Post-processing data analysis was used ArcGIS software to determine the results of crossing the SST contour and Chl-a combination to obtain the optimal potential location for the Marine Aquaculture Zone (MAZ). Image data processing shows the lowest potential marine aquaculture location was in Bintan Island in West Season with 202 MAZ. The highest potential location for marine aquaculture on Bintan Island in North Season with 584 MAZ. The results showed the potential location for marine aquaculture locations in Bintan Island was widely distributed, and most of the locations far from the coastline of eastern Bintan Island. This study indicates that the east part of Bintan Island has the potential to be implemented for marine aquaculture areas to develop sustainable marine aquaculture production.

A Tri-Satellite Interference Source Localization Method for Eliminating Mirrored Location.

With the increase in satellite communication interference, the tri-satellite time difference of arrival (TDOA) localization technique, which is an effective method to determine the location of the interference using sensors or antennas, has been developed rapidly. The location of the interference source is determined through the intersection of the TDOA lines of position (LOP). However, when the two TDOA LOP have two mirrored intersection points, it is theoretically difficult to determine the real location. Aiming at this problem, a method for eliminating mirrored location based on multiple moment TDOA is proposed in this paper. First, the TDOA results are measured at multiple moments using the cross-ambiguity function (CAF), and the localization equation set is established based on the World Geodetic System (WGS)-84 earth ellipsoid model. Then, the initial location result can be obtained by solving the equation set through the Newton iteration method. Finally, the high-precision location result after eliminating the mirrored location is obtained after the single moment localization based on the initial location. Simulation experiments and real measured data processing results verify the effectiveness of the proposed method. It still has good robustness under the condition of large measurement errors and deviations from the prior initial values.

GEODETIC ERRORS ARISING FROM THE DIFFERENCES BETWEEN SK-42 AND WGS-84 COORDINATE SYSTEMS WHEN IMPLEMENTED IN MODERN WEAPONS SYSTEMS

Modern weapons, technological systems, and facilities used in our days mainly are either managed with digital topographic maps produced in WGS-84 (World Geodetic System-1984) coordinate system or are connected with Military Geographic Information System (MGIS) created on the base of this coordinate system. If we use topographic maps based on the 1942 coordinate system in computer systems of modern weapons, and other technological systems and facilities, then it will be inevitable to encounter some geodesy related errors. In this article, these errors and their possible solutions are explained in the case of using the Krassovsky coordinate system in Azerbaijan.

A Plan for Applying Cadastral Record to the Transformation of Cadastral Coordinates into the World Geodetic System

A Plan for Applying Cadastral Record to the Transformation of Cadastral Coordinates into the World Geodetic System

Construction and Accuracy Analysis of a BDS/GPS-Integrated Positioning Algorithm for Forests

The objective of this study was to construct a BeiDou navigation satellite system (BDS)/global positioning system (GPS)-integrated positioning algorithm that meets the accuracy requirement of forest surveys and to analyze its accuracy to provide theoretical and technical support for accurate positioning and navigation in forests. The Quercus variabilis broad-leaved forest in Jiufeng National Forest Park and the Sabina Coniferous forest in Dongsheng Bajia forest farm were selected as the study area. A Sanding T-23 multi-frequency three-constellation receiver and a u-blox NEO-M8T multi-constellation receiving module were used for continuous observation under the forest canopy. Compared with T-23, the u-blox NEO-M8T is much lighter and more flexible in the forest. The BDS/GPS-integrated positioning algorithm for forests was constructed by temporally and spatially unifying the satellite systems and using a reasonable observed value weighting method. Additionally, the algorithm is also written into the RTKLIB software to calculate the three-dimensional (3D) coordinates of the forest observation point in the World Geodetic System 1984 (WGS-84) coordinate system. Finally, the results were compared with the positioning results obtained using GPS alone. The experimental results indicated that, compared with GPS positioning, there were 13–27 visible satellites available for the BDS/GPS-integrated positioning algorithm for forests, far more than the satellites available for the GPS positioning algorithm alone. The Position Dilution of Precision (PDOP) values for the BDS/GPS-integrated positioning ranged from 0.5 to 1.9, lower than those for GPS positioning. The signal noise ratio (SNR) of the BDS/GPS-integrated satellite signals and GPS satellite signals were both in the range of 10–50 dB-Hz. However, because there were more visible satellites for the BDS/GPS-integrated positioning, the signals from the BDS/GPS-integrated satellites were stronger and had a more stable SNR than those from the GPS satellites alone. The results obtained using the BDS/GPS-integrated positioning algorithm for forests had significantly higher theoretical and actual accuracies in the X, Y and Z directions than those obtained using the GPS positioning algorithm. This suggests that the BDS/GPS-integrated positioning algorithm can obtain more accurate positioning results for complex forest environments.

A comparison of existing transformation models to improve coordinate conversion between geodetic reference frames in Nigeria

Efficient transformation parameters are key to effective geodetic operations between any systems. With the advancement in technology, an improved interaction between geodetic reference frames has been noticed irrespective of their inherent heterogeneous deformations and the intermittently present oversight that exist as a result of the conversion methodology. The spatial data captured using the Global Navigation Satellite System (GNSS) have a reference datum based on the World Geodetic System 1984 (WGS84) ellipsoid. These data usually require a transformation to a local projection with its ellipsoid and datum and vice versa. These geodetic operations are unavoidably vulnerable to data loss due to distortion, especially if the applied model is unsuitable for the transformation between reference frames. Therefore, the main aim of this study is to authenticate the existing set of parameters for the local and geocentric systems in Nigeria by assessing the efficacy of the Bursa Wolf (BW) and the Molodensky Badekas (MB) models. To this end, both models (BW and MB) are compared in this study and used in the development of the Helmerts seven transformation parameters between Minna datum (Clarke 1880) and WGS84 reference ellipsoids for a large region in Southern Nigeria. Results show that the sets of datum shift transformation parameters for both models (a scale factor with three sets of translational and rotational parameters), derived from the exercise of the BW and the MB models revealed a high degree of correlation between the expected and derived set of coordinates during the validation/testing phase using each set of models. The validation exercise was carried out on a total of seven points, which were not part of the original computations. These points were distributed across the region to provide a better framework and a higher confidence level. Overall, an improvement of 68% is observed in terms of the correlation between expected and derived coordinates in the validation points and from the obtained root mean square values. Ultimately, the MB model is preferred to the BW model evidently because the transformation involves a global–local reference frame.

Analysis and Discussion on the Optimal Noise Model of Global GNSS Long-Term Coordinate Series Considering Hydrological Loading

The displacement of Global Navigation Satellite System (GNSS) station contains the information of surface elastic deformation caused by the variation of land water reserves. This paper selects the long-term coordinate series data of 671 International GNSS Service (IGS) reference stations distributed globally under the framework of World Geodetic System 1984 (WGS84) from 2000 to 2021. Different noise model combinations are used for noise analysis, and the optimal noise model for each station before and after hydrologic loading correction is calculated. The results show that the noise models of global IGS reference stations are diverse, and each component has different optimal noise model characteristics, mainly white noise + flicker noise (WN+FN), generalized Gauss–Markov noise (GGM) and white noise + power law noise (WN+PL). Through specific analysis between the optimal noise model and the time series velocity of the station, it is found that the maximum influence value of the vertical velocity can reach 1.8 mm when hydrological loading is considered. Different complex noise models also have a certain influence on the linear velocity and velocity uncertainty of the station. Among them, the influence of white noise + random walking noise is relatively obvious, and its maximum influence value in the elevation direction can reach over 2 mm/year. When studying the impact of hydrological loading correction on the periodicity of the coordinate series, it is concluded whether the hydrological loading is calculated or not, and the GNSS long-term coordinate series has obvious annual and semi-annual amplitude changes, which are most obvious in the vertical direction, up to 16.48 mm.

Arne Bjerhammar- a personal summary of his academic deeds

Abstract Arne Bjerhammar is well known worldwide mainly for his research in physical geodesy but also for introducing a new matrix algebra with generalized inverses applied in geodetic adjustment. Less known are his developments in geodetic engineering and contributions to satellite and relativistic geodesy as well as studies on the relation between the Fennoscandia land uplift and the regional gravity low. Most likely part of his research has contributed to worldwide political relaxation during the cold war, which deed was honored by a certificate of achievement awarded by the Department of Research of the US army as well as the North Star Order by the King of Sweden. Arne Bjerhammar’s pioneer scientific production, in particular on a world geodetic system, towards what would become GPS, as well as relativistic geodesy, is still of great interest among the worldwide geodetic community, while the memories and spirit along his outstanding academic deeds have more or less fainted away from his home university (KTH) only a decade after he passed away.

The potential study of fishing area and its relationship to marine security in Natuna island

Natuna Island is one of the small outer islands in Indonesia bordering Malaysia, Singapore, Thailand, Vietnam, and directly facing the South China Sea. Natuna seawaters have enormous potential fishery resources and one of the fishing areas used as a fishing activity for Indonesian and foreign fishermen. The potential also made illegal fishing practice rampant in Natuna seawaters and led to the Indonesian maritime security patrol being directed to Natuna seawaters to stop the illegal fishing process. The marine security patrol activities require high operational costs, and This can be minimized in several ways, particularly by knowing the points that can contain extensive fish resources, and the security patrols can be carried out directly at these points of location. To obtain information about these locations, map the potential fishing areas in Natuna seawaters for each period or monsoon. This study aims to apply remote sensing analysis to collect comprehensive information regarding strategic fishing areas prone to violations and security threats related to fishing activities based on monthly analyzes. The data used in this study were chlorophyll-a concentration and SST from MODIS level-3 with a resolution of 4 km from January to December 2019. SST and chlorophyll-a concentration data used pre-process analysis with SeaDas Software to ensure the data projection in the World Geodetic System (WGS) 84 format. The data processing stage uses ER Mapper software to project the distribution of SST and chlorophyll-a concentration into a contour. Post-processing data used ArcGIS software to determine crosses’ results on the SST contour and the combined chlorophyll-a concentration. Image data processing results show that the lowest fishing point on Natuna Island in August with 51 fishing points, and the highest fishing point on Natuna Island in February with 584 fishing points. The results showed that fishing points vulnerable to illegal fishing are mostly located in the northern part of Natuna Island. The fishing zone is mostly far from Natuna island’s coastal line. The results of this study indicate that the fishing area in the outer regions of Natuna Island needs to be increased in security and protection, especially in regions with a high level of fishing activity. This information is expected to become a reference for the authorities in the marine security sector in Natuna waters to take certain policies related to marine security patrols’ operational activities in Natuna waters, particularly in minimizing operational costs of marine security patrols in Natuna seawaters.

PENINJAUAN STATUS LINGKUNGAN EKSISTING SUNGAI MARIKINA, FILIPINA

Abstract: The physico-chemical characteristics of the Marikina River in an urban area of Metro Manila, Philippines was determined to evaluate the current degree of pollution. The study focused on one source at the site with general coordinates of 14°38’07.95” N, 121°05’36.33” E based on the World Geodetic System (WGS), at an average surface water elevation of around 9 m above mean sea level (AMSL). The area was chosen because of its proximity to a main road and the presence of an outfall from a cemented pipe near a major shopping mall. Comparing the results from the sampling source with the DENR effluent standards for surface waters based on (DAO-2016-08, US-EPA), the effluent is considered as too polluted to be discharged to the surface water in terms of Total Dissolved Solids (TDS: 608.9 mg/L) and Phosphates (PO4: 12.46 mg/L). The pH (6.9) and Nitrate (0.17 mg/L) of the effluent conforms to standards. A Stream Visual Assessment Protocol was conducted with a resulting Protocol Score of 5.7, which is relatively low for a moving water body. The failure to conform to set standards using the physico-chemical components is supported by the land-use profile which shows that domestic (85%), industrial/commercial (10%) and agricultural wastes (5%) greatly affect the water quality of the river. It is our recommendation therefore that continuing information and education campaigns for the maintenance of water quality be regularly conducted for the residents along the riverbanks to create awareness of the importance of keeping the water clean through minimum direct waste contributions. Keywords: Physico-Chemical characteristics, Marikina river, water quality

The Importance of the Coordinate Transformation Process in Using Heterogeneous Data in Coastal and Marine Geographic Information System

Coastal and Marine Geographic Information Systems (CMGISs) permit to collect, manage, and analyze a great amount of heterogeneous data concerning coastal, sea, and ocean environments, e.g., nautical charts, topographic maps, remotely sensed images. To integrate those heterogeneous layers in CMGIS, particular attention is necessary to ensure the perfect geo-localization of data, which is a basic requirement for the correct spatial analysis. In fact, the above-mentioned types of information sources are usually available in different cartographic projections, geodetic datum, and scale of representation. Therefore, automatic conversions supplied by Geographic Information System (GIS) software for layer overlay do not produce results with adequate positional accuracy. This paper aims to describe methodological aspects concerning different data integration in CMGIS in order to enhance its capability to handle topics of coastal and marine applications. Experiments are carried out to build a CMGIS of the Campania Region (Italy) harmonizing different data (maps and satellite images), which are heterogeneous for datum (World Geodetic System 1984 and European Datum 1950), projection (Mercator and Universal Transverse of Mercator), and scale of representation (large and medium scale). Results demonstrate that automatic conversion carried out by GIS software are insufficient to ensure levels of positional accuracy adequate for large scale representation. Therefore, additional operations such as those proposed in this work are necessary.

First report of Fusarium oxysporum f. sp. cubense tropical race 4 (TR4) causing banana wilt in the Island of Mayotte.

Fusarium oxysporum f. sp. cubense (Foc) is a fungus causing Fusarium wilt of banana (Musa spp.). The fungus is divided into three races and 24 vegetative compatibility groups (VCG) of which VCG 01213/16, commonly known as Foc tropical race 4 (Foc TR4), is of particular concern. Foc TR4 severely affects Cavendish (AAA) bananas, which comprise about 50% of all bananas produced globally, as well as many varieties susceptible to the other races of Foc. The pathogen was restricted to Southeast Asia and Australia until 2012, where after it has been detected in the Middle East, Mozambique in Africa, and Colombia in South America (Viljoen et al. 2020). Here we report the first detection of Foc TR4 in the French department of Mayotte, located in the Indian Ocean. In September 2019, leaf yellowing and wilting symptoms were observed in individual plants of the banana subgroups Silk (AAB) (cv. "Kissoukari") and Bluggoe (ABB) (cv. "Baraboufaka"). The symptomatic individuals were found in private gardens in the village of Poroani in Southwest Mayotte (World Geodetic System [WGS] 12° 53' 31.83''S, 45° 8' 30.98" E). When the pseudostems of symptomatic plants were split open, dark red to brown vascular discoloration was observed. Pseudostem tissue samples were collected and identified as Foc TR4 with the real-time PCR assay developed by Aguayo et al. (2017). Sections of the pseudostem samples were surface sterilized and used to isolate the fungus on potato dextrose agar (PDA) medium. Isolates were identified as F. oxysporum based on cultural and morphological characteristics as described in Leslie and Summerell (2006), which included fluffy aerial mycelia on PDA and the presence of short monophialides conidigenous cells bearing microconidia arranged in false heads. Abundant chlamydospores were also produced on synthetic nutrient poor agar (SNA) media. Single-spored isolates were used to develop nit mutants for vegetative compatibility group (VCG) testing (Correll 1991; Puhalla 1985). The isolates were confirmed as VCG 01213/16 as formation of heterokaryons was obtained with the nit mutants of the universal Foc TR4 tester. Two VCG 01213/16 isolates were then selected for pathogenicity testing by inoculating 2-month-old tissue culture-derived Cavendish plants, using the method described by Viljoen et al. (2017). After 10 weeks, the Foc TR4-inoculated plants produced wilting symptoms and internal rhizome discoloration typical of Fusarium wilt. Fusarium oxysporum was re-isolated from the inoculated plants and identified as Foc TR4/VCG 01213/16 by PCR (Dita et al. 2010; Matthews et al. 2020), thereby fulfilling Koch's postulates. Local authorities have destroyed the infected plants, and have undertaken an extensive survey to determine the distribution of Foc TR4 on the island. Three additional positive cases, identified with the real-time PCR assay of Aguayo et al. (2017), were found in the localities of Koungou ([WGS] 12° 44' 03''S, 45° 12' 08" E) and Bouéni ([WGS] 12° 54' 25''S, 45° 04' 43" E). These included infected Cavendish banana (AAA) plants (cv. "Kontriké"). This is the first time that Foc TR4 has been found on a banana variety other than Cavendish when newly detected in a country. Considering the proximity of Mayotte to other islands of the Comoros archipelago, Madagascar and the East African coast, where banana is considered an important staple, this report describes a serious threat to banana production and the livelihoods of people in the region.

Analysis of historical dataset based on Rennell’s map on Ganges River basin

Rennell has been widely known as the father of the modern maps since the publication of his survey works of 1760s. He made the first nearly accurate map of the then Bengal of the Indian Subcontinent entitled “A Bengal Atlas (1779)”, a work which was considered as the most significant geographical contributions of the British Empire for their strategic and administrative interests. The most important feature of the Atlas is the Ganges Basin which flows as the trans-boundary River of South Asia entrenching India, China and Bangladesh. This study reveals the historical and contextual phenomena of the river like old channels, onomastic and old administrative footprints from Rennell’s Atlas around the old courses of Ganges River, more specifically Plate 18 confining within the territorial extent of current Bangladesh Boundary entrapping the history more than 250 years of the aerial extent encompassing 11,651 km2. This research also reveals the map accuracy by calculating the modern graticules comparing the former geographic coordinate systems. In order to develop historical dataset based on Rennell’s map, various modern tools of renowned GIS approaches and corresponding attributes like geo-referencing, digitizing, geo-corrections, projection transformation, calculating geometry, pivot table etc. In the 1760s, Rennell was dependent on the primitive sextant instrument and calculated latitude, longitude assuming Fort William of Kolkata as Zero (0) degree. In this research we integrated Bangladesh Transverse Mercator (BTM) considering World Geodetic System 1984 as datum. The results illustrate the volume of rivers, riverine forest, jheel, char land are occupying 116,600; 215,959; 3573; and 15,471 ha respectively in the Rennell’s map which are currently almost disappeared. In the said plate, marsh land covered the maximum area about 118,676 ha while length of Kaccha (unmetalled) road was 1339 km, though recently metalled road length has been increased dramatically. The detected broad administrative unit was 337. The error result in the present research is with 99% accuracy. This research has highlighted the strengths to retrieve underlying evidences and relevant features and statistical/attribute data from the historical maps using remote Sensing (RS) and Geographic Information System (GIS) approaches.