GIS Operations Research Articles

ChatGeoAI: Enabling Geospatial Analysis for Public through Natural Language, with Large Language Models

Large Language Models (LLMs) such as GPT, BART, and Gemini stand at the forefront of Generative Artificial Intelligence, showcasing remarkable prowess in natural language comprehension and task execution. This paper proposes a novel framework developed on the foundation of Llama 2, aiming to bridge the gap between natural language queries and executable code for geospatial analyses within the PyQGIS environment. It empowers non-expert users to leverage GIS technology without requiring deep knowledge of geospatial programming or tools. Through cutting-edge Natural Language Processing (NLP) techniques, including tailored entity recognition and ontology mapping, the framework accurately interprets user intents and translates them into specific GIS operations. Integration of geospatial ontologies enriches semantic comprehension, ensuring precise alignment between user descriptions, geospatial datasets, and geospatial analysis tasks. A code generation module empowered by Llama 2 converts these interpretations into PyQGIS scripts, enabling the execution of geospatial analysis and results visualization. Rigorous testing across a spectrum of geospatial analysis tasks, with incremental complexity, evaluates the framework and the performance of such a system, with LLM at its core. The proposed system demonstrates proficiency in handling various geometries, spatial relationships, and attribute queries, enabling accurate and efficient analysis of spatial datasets. Moreover, it offers robust error-handling mechanisms and supports tasks related to map styling, visualization, and data manipulation. However, it has some limitations, such as occasional struggles with ambiguous attribute names and aliases, which leads to potential inaccuracies in the filtering and retrieval of features. Despite these limitations, the system presents a promising solution for applications integrating LLMs into GIS and offers a flexible and user-friendly approach to geospatial analysis.

Analysis of spatio-temporal development of mining landforms using aerial photographs: Case study from the Ostrava–Karviná mining district

Abstract The anthropogenic relief transformations of the mining landscape are characterised by high dynamics of changes over time that can be effectively mapped on a large scale using aerial images. The Karviná part of the Ostrava-Karviná mining district, which stands for significant hard coal mining area in the Czech Republic, has been selected to analyse the spatio-temporal development of anthropogenic landforms. Anthropogenic landforms were visually identified from the aerial images from 1947, 1966, 1971, 1985, 1994, 2009, and 2018. Specific anthropogenic landforms were analysed along with their spatio-temporal changes based on obtained vector data. The total extent and number of anthropogenic landforms increased the most during the periods 1947–1966 and 1971–1985. The same anthropogenic landforms occurred on circa 24 hectares in the entire period 1947–2018. The most anthropogenic landforms remained preserved in the last observed period 2009–2018. The multi-temporal analysis of aerial photographs and overlay operations in GIS enabled to map the age of specific landforms and to identify changed or unchanged anthropogenic landforms. This method is suitable for the study of landform dynamics at mining sites and is particularly relevant for the planning challenges in post-mining reclamation.

Оценка уязвимости карстовых подземных вод к загрязнению на основных массивах Горного Крыма с использованием региональной методики

Introduction. Assessment of groundwater vulnerability to contamination is an effective tool for scientific substantiation of the sanitary protection zones for drinking water sources. Karst ground waters of the Mountain Crimea form the main resources for water supply in the Crimean Peninsula. This study has a purpose to perform the assessme nt and mapping of karst ground waters resource vulnerability to contamination on such representative massifs of the Crimean Mountains as Chatyrdag, Dolgorukovsky, Karabi and Ay-Petri . Materials and methods. Assessment of karst ground waters vulnerability is conducted by use of Mountain -Crimean method. It has been developed on the base of some wide-tested European methods (COP-method and Slovene approach) with methodological modification and adaptation to regional conditions of the Mountain Crimea. The input data for assessment is spatial information about ground waters vulnerability factors: protective layers in vadose zone, flow concentration by streams, sinkholes and caves, precipitation regime etc. The collected spatial information was converted into attributed geo data layers, which were subsequently subjected to overlay operations in Arc GIS 10 software according to assessment scheme. Results. According to the assessment results, approximately 34 and 14% of the Chatyrdag massif area gained the category of high and very high vulnerability, on the Karabi massif – 14 and 17%, on the Dolgorukovsky massif – 14 and 2%, on the Ay-Petri massif – 19 and 7% of total area respectively. The result ing vulnerability maps demonstrate significant mosaics and contrast, which is associated with discrete distribution of protective covers and high differentiation of ground water recharge conditions within the catchments of karst massifs. Discussion. Analysis of the resulting vulnerability maps have revealed that the leading factors determining areas of high and very high vulner ability of karst waters are runoff concentration factors, while the factors of protective cover mainly determine the areas with low vulnerability. The zones of high vulnerability on the Chatyrdag and Karabi massifs are mainly coincide with areas of high density of karst forms (sinkholes and caves), while high vulnerability zones of the Ay-Petri and Dolgorukovsky massifs are predominantly associated with areas near permanent and temporary watercourses. In general, the obtained maps of groundwater vulnerability are quite consistent with the known data on the hydro-geological conditions of the assessed massifs. Conclusions. The identified differences in the area ratio and spatial distribution of ground waters vulnerability categories between the assessed massifs are a consequence of local geological, geo-morphological and hydrological features. The obtained results confirm high applicability of the Mountain-Crimean regional method for groundwater vulnerability assessment, at least for the karst massifs of the Mountain Crimea. Suggestions for practical application and direction for future research. The produced groundwater vulnerability maps create a scientific basis for delineation of water protection zones, assessing the risks of groundwater pollution and developing the territorial planning schemes within studied areas. The next stage of study is an assessment of groundwater source vulnerability for individual karst springs used in water supply.

Spatial Evaluation of a Natural Flood Management Project Using SAR Change Detection

This study proposes an evaluation method using C-band Sentinel-1 synthetic aperture radar (SAR) data to provide evidence of flood characteristic changes after the restoration of a floodplain. A portable, flexible evaluation framework has replicated previous change detection research approaches to analyse a Natural Flood Management (NFM) project on the Sussex Ouse river in southern England, conducted by the Sussex Flow Initiative (SFI), to ascertain how control measures have helped mitigate flood risk. GIS operations were conducted on the mapped results of the change detection procedure to identify how flood area, form and compactness have been affected after the NFM installation restored a floodplain to slow river flow and how these changes relate to the overall aims of the project. Innovative means were employed to verify the change detection methodology by sampling flood records from internet-published drone footage. The overall accuracy achieved using the Change Detection and Thresholding (CDAT) technique was 75%. The use of SAR data provides evidence of how NFM features function during significant flood events, providing a mapped delineation of the actual flood extent. A comprehensive scorecard has been developed to evaluate the positive and negative outcomes of the spatial changes that have manifested in post-restoration floods, in comparison to inundation before the installation. Results from this study have been included in the annual report of the SFI project to demonstrate how key features have attenuated flood waters in accordance with design intentions.

A Case Analysis of Particle Defects Found in 220kV GIS by Ultrasonic Partial Discharge and SF6 Gas Decomposition Products Joint Detection

The particles inside GIS have become the biggest factor affecting the safe and stable operation of GIS. How to effectively and timely find the particle defects is very important to ensure the reliable operation of GIS. This article describes in detail how to find particles in GIS through ultrasonic partial discharge method and comprehensive diagnosis of SF6 gas decomposition products, and gives specific solutions, which will provide very useful experience for subsequent GIS operation and maintenance.

Application of Ultrasonic Testing Method in Particle Detection of GIS Handover Test

Ultrasonic partial discharge detection is a necessary test in GIS handover test, which is very significant to detect the internal defects of GIS. This article introduces in detail how the ultrasonic partial discharge detection method is applied to the GIS handover test through a case in which the internal particles are found through the ultrasonic partial discharge detection method in the GIS handover test. It also fully proves that the ultrasonic partial discharge detection method is very effective for discovering the internal particles of GIS through this case. The experience of this case can provide a very meaningful experience for the subsequent GIS handover, operation and maintenance tests.

Long-Term Partial Discharge Behavior of Protrusion Defect in HVDC GIS

This article investigates the partial discharge (PD) behavior of protrusion defects in real-size high-voltage direct current gas insulated switchgear (HVDC GIS) for SF6 and SF6 alternative gases including fluoronitrile–CO2 mixture (10%) and fluoroketone–dry air mixture (6.6%). The evolution of PD apparent charge and PD repetition rate for all investigated gases is presented and discussed. The measurement results indicate that PD behavior changes as a function of time. The PD apparent charge increases and the PD repetition rate decreases with the increase of voltage application time. This evolution can be related to the change in protrusion tip radius due to electrochemical etching: radius of the protrusion’s tip being enlarged. In addition, the pulse sequence analysis (PSA) plots of the PDs caused by this defect are presented. It is observed that the PSA plots change over time. Therefore, for the development of a robust PD monitoring and defect-recognition tool, as well as for the assessment of risks in the operation of HVDC GIS, it is crucial to take these changes into account.

Prospects for improving geostrategic asset management of the country on the basis of the unified spatial data system

In the article, the authors considered the theoretical provisions of the use of geographical information systems in cadastral activities. The paper analyzed the regulatory framework of cadastral activities, the provision of information and cartographic information. The authors noted that significant attention is paid to the provision of public services in the field of cadastre in electronic form and the implementation of cadastral activities using Internet technologies. The authors also mentioned that to date, a huge number of different software systems with distinctive features that are necessary for the effective conduct of cadastral activities have been developed in the country. The paper contains the most common violations in the establishment of territorial zones, implements the experience of using the functionality of GIS, examines the stages of checking for violations of semantic and graphical data, and makes proposals aimed at eliminating errors in order to place land plots on state cadastral registration. In order to ensure the correct operation of information systems, it’s advisable to determine the legal relations associated with the lawful creation and operation of GIS that meet the requirements of the legislation of the Russian Federation. Nowadays it is also necessary to develop a number of domestic GIS for the purposes of cadastral activities.

Study on the characteristics of the potential rise of shell under VFTO in the GIS pumped storage power station

Compared with the traditional GIS station, complex wiring and operation mode of pumped-storage plant diversity, working condition of frequent transformation, makes the plant to produce very fast transient overvoltage (VFTO) probability increase greatly. VFTO will form a transient coupled to the GIS shell casing transient earth voltage (TEV), and then to station personnel safety and the reliability of the secondary equipment poses a great threat. But at the moment because of the limitation of testing technology such as understanding of the academic study of TEV is lack of system. Based on a typical 500 kV gis pumped-storage power station, this paper established a system equivalent model of GIS, network frame and calculates the amplitude, frequency spectrum characteristic of the TEV and influence on VFTO characteristics, and analyzes the fault location, power supply mode, branch bus, the influence of vertical grounding electrodes on the TEV characteristics, For the characteristics of the TEV rules and parameters. Research on TEV characteristics of GIS of pumped storage power station has important reference value for further perfecting relevant theories.

A new method for evaluating the spatial correspondence between surface and subsurface geological lineaments: A case from the Potiguar Basin, NE Brazil

This paper provides a new technique for evaluating lineaments that focuses on the spatial link between surface and subsurface elements in a single layer. We chose a test area in northeast Brazil's Borborema Province. We extracted magnetic and relief lineaments from aeromagnetic and SRTM data. We defined the lineaments that agree on both layers using GIS operations. To identify the concordance between lineaments, we constructed kernel density maps that combined the data from each layer. We detected NE-SW solid conditioning of the structures. Even when evaluating only the concordant lineaments in other directions, they are expressed in groupings in NE-SW, as with NW-SE features, that associates with transfer failures and are contained by large NE-SW structures. The Atlantic Ocean's opening and expansion phases were linked to the E-W direction, also truncated by NE-SW lower density sections. The N–S trend was inexpressive. Areas with a higher density of concordant lineaments were associated with regions more susceptible to the Neotectonics of landform inversion, forming domes and arches-oriented NE-SW, as in Serra do Mel, Macau High, and Ponta Grossa High. Lower lineament density areas indicated visual correspondence with the most significant number of production wells in the Potiguar Basin, indicating that these regions are more favorable for the accumulation and trapping of hydrocarbons.

A GIS Partial Discharge Defect Identification Method Based on YOLOv5

The correct identification of partial discharge types is of great significance to the stable operation of GIS. In order to improve the recognition accuracy and result of partial discharge, and to meet the requirements of real-time monitoring of GIS equipment, this paper proposes a GIS partial discharge defect recognition model based on YOLOv5. First, the GIS partial discharge simulation experiment is established to create the dataset of partial discharge PRPD map. Then, a YOLOv5-based GIS partial discharge defect recognition model is constructed, and different training methods are used to optimize the parameters of the model. By comparing with target detection models based on other deep learning methods, such as Faster-RCNN and YOLOv4, the YOLOv5 model discussed in the paper has significantly improved the recognition efficiency and recognition accuracy, in which mAP value is 95.89% and FPS is 28.89. In addition, the model can realize the distinction and identification of multiple PD types in a single PRPD map. At last, the YOLOv5-based GIS partial discharge defect identification model is applied to the test in a 500 kV substation. The model accurately determines the type of GIS partial discharge, which verifies the accuracy and validity of the model.

Research on Conducted Disturbance to Secondary Cable Caused by Disconnector Switching Operation

The disconnector switching operation in GIS not only generates very fast transient overvoltage (VFTO) in primary equipment, but also couples to the secondary system, which affects normal operation of the secondary equipment. In this study, aiming at the conducted disturbance caused by the disconnector switching operation of the 1,000-kV UHV GIS test circuit on the secondary cable, a broadband equivalent circuit model of the potential transformer and the grounding grid is proposed based on the vector fitting method and the impedance synthesis method, and the accuracy of the model is tested. On the basis of this model, the conducted disturbance voltage of the secondary cable core is obtained by combining the measured typical disturbance source waveform. The research results of the influencing factors of conducted disturbance show that the amplitude of the disturbance voltage generated by the capacitive conduction is higher than that generated by the resistive conduction, but the main frequency of the resistive conducted disturbance voltage is higher. The amplitude of the conducted disturbance voltage will decrease with the increase of the length of the cable and the length of the grounding wire. The single-ended grounding of the secondary cable shield at the GIS side will cause serious disturbance voltage. The research results of this study will be beneficial to the protection of secondary cable electromagnetic disturbance in the intelligent substation and have reference significance for the implementation of secondary equipment protection measures in the intelligent substation.

The Research of GIS Discharge Influence Based on Particle Properties in Installation Environment

In order to explore the influence of atmospheric free particles that exit during GIS installation on the stable operation of GIS, the size, shape and inner properties of the particles contained in the air are analyzed. And based on 500kV GIS equipment, the GIS gas chamber model and the model of free particles were established. By using the finite element simulation software, the surface electric field distribution when the free particles remain on the insulator surface is solved. The results show that the electric field distribution of particles which exist along the surface of insulator is directly related to the relative permittivity of the material of the particles themselves, and the intensity of the electric field along the surface increases with the increase of the relative permittivity. with the fact that the relative permittivity of air particles is almost below 20, as a result, the existence of 10µm grade non-metallic free particles will not cause flashover discharge. But, when a small number of Fe3O4 particles which size over 1mm or when them accumulate regularly, it will lead to flashover discharge. Therefore, the suspended atmospheric particles in the installation environment have little impact on the stable operation of GIS. When considering the installation environmental conditions, the installation can be carried out on a clear, windless day which can save costs.

Geoportal for highways as a basic element of spatial data infrastructure

This article is devoted to the development of geographic information systems, WEB-mapping and information integration into the spatial data infrastructure (SDI). The analysis of the history of the creation of spatial data infrastructure in the world community and in Russia is carried out, the specifics of the development of Web-GIS and SDI are revealed. As part of the study, the analysis of the world experience of using the Web-GIS of highways, as well as the current state of applied geoinformation systems in Russia was carried out. The key issue considered in the article is the development of the architecture of a Web GIS (geoportal) of highways for the purposes of accounting, analysis and systematization of spatial data. The main features of the formation of systems for recording data on highways are determined, the main tasks solved by these systems are given. The automobile road is a complex and lengthy object, which should become the spatial basis for the development of spatial data infrastructure in Russia. A block diagram of the main modules of the geoportal has been developed and proposed. The main functionalities implemented at each stage of the Web GIS operation are highlighted. As a result of the implementation of the proposed architecture of the geoportal, a system of analysis, systematization and management of spatial data of a road enterprise was introduced. The use of a geoportal significantly affects the optimization of the performance of various works on highways. Also, the result of the work (Web-GIS) can be implemented as a system for analysis, accounting and systematization of data on other extended linear objects (power lines, gas pipelines, water pipelines, etc.). A user interface of a geoportal, a structure for storing spatial data, modules for transforming coordinates and information, blocks for loading, analyzing and unloading data have been developed. The proposed architecture is versatile and easy to use, which is a clear advantage over the analog systems described in the study. Further study of the research topic opens up prospects for the rapid development of integrated geoinformation software tools on the Internet and a deeper understanding of the need to develop spatial data infrastructure.

Efficient Hazard Assessment for Pluvial Floods in Urban Environments: A Benchmarking Case Study for the City of Berlin, Germany

The presence of impermeable surfaces in urban areas hinders natural drainage and directs the surface runoff to storm drainage systems with finite capacity, which makes these areas prone to pluvial flooding. The occurrence of pluvial flooding depends on the existence of minimal areas for surface runoff generation and concentration. Detailed hydrologic and hydrodynamic simulations are computationally expensive and require intensive resources. This study compared and evaluated the performance of two simplified methods to identify urban pluvial flood-prone areas, namely the fill–spill–merge (FSM) method and the topographic wetness index (TWI) method and used the TELEMAC-2D hydrodynamic numerical model for benchmarking and validation. The FSM method uses common GIS operations to identify flood-prone depressions from a high-resolution digital elevation model (DEM). The TWI method employs the maximum likelihood method (MLE) to probabilistically calibrate a TWI threshold (τ) based on the inundation maps from a 2D hydrodynamic model for a given spatial window (W) within the urban area. We found that the FSM method clearly outperforms the TWI method both conceptually and effectively in terms of model performance.

A Tool for the Automatic Aggregation and Validation of the Results of Physically Based Distributed Slope Stability Models

Distributed physically based slope stability models usually provide outputs representing, on a pixel basis, the probability of failure of each cell. This kind of result, although scientifically sound, from an operational point of view has several limitations. First, the procedure of validation lacks standards. As instance, it is not straightforward to decide above which percentage of failure probability a pixel (or larger spatial units) should be considered unstable. Second, the validation procedure is a time-consuming task, usually requiring a long series of GIS operations to overlap landslide inventories and model outputs to extract statistically significant performance metrics. Finally, if model outputs are conceived to be used in the operational management of landslide hazard (e.g., early warning procedures), the pixeled probabilistic output is difficult to handle and a synthesis to characterize the hazard scenario over larger spatial units is usually required to issue warnings aimed at specific operational procedures. In this work, a tool is presented that automates the validation procedure for physically based distributed probabilistic slope stability models and translates the pixeled outputs in warnings released over larger spatial units like small watersheds. The tool is named DTVT (double-threshold validation tool) because it defines a warning criterion on the basis of two threshold values—the probability of failure above which a pixel should be considered stable (failure probability threshold, FPT) and the percentage of unstable pixels needed in each watershed to consider the hazard level widespread enough to justify the issuing of an alert (instability diffusion threshold, IDT). A series of GIS operations were organized in a model builder to reaggregate the raw instability maps from pixels to watershed; draw the warning maps; compare them with an existing landslide inventory; build a contingency matrix counting true positives, true negatives, false positive, and false negatives; and draw in a map the results of the validation. The DTVT tool was tested in an alert zone of the Aosta Valley (northern Italy) to investigate the high sensitivity of the results to the values selected for the two thresholds. Moreover, among 24 different configurations tested, we performed a quantitative comparison to identify which criterion (in the case of our study, there was an 85% or higher failure probability in 5% or more of the pixels of a watershed) produces the most reliable validation results, thus appearing as the most promising candidate to be used to issue alerts during civil protection warning activities.

Enriching the metadata of map images: a deep learning approach with GIS-based data augmentation

ABSTRACT Maps in the form of digital images are widely available in geoportals, Web pages, and other data sources. The metadata of map images, such as spatial extents and place names, are critical for their indexing and searching. However, many map images have either mismatched metadata or no metadata at all. Recent developments in deep learning offer new possibilities for enriching the metadata of map images via image-based information extraction. One major challenge of using deep learning models is that they often require large amounts of training data that have to be manually labeled. To address this challenge, this paper presents a deep learning approach with GIS-based data augmentation that can automatically generate labeled training map images from shapefiles using GIS operations. We utilize such an approach to enrich the metadata of map images by adding spatial extents and place names extracted from map images. We evaluate this GIS-based data augmentation approach by using it to train multiple deep learning models and testing them on two different datasets: a Web Map Service image dataset at the continental scale and an online map image dataset at the state scale. We then discuss the advantages and limitations of the proposed approach.

Discrepancies in the spatial extent of common GIS highway networks

AbstractThe Federal Highway Administration's Highway Performance Monitoring System (HPMS) and the U.S. Census Bureau's TIGER geospatial database are relied on by countless professionals, but the two databases differ by 6.9 million km (4.3 million miles), a discrepancy greater than the Federal Highway Administration's national total of 6.6 million km (4.1 million miles). While there are several methodological reasons why a GIS network will give different answers from the HPMS, these cannot explain a difference of this magnitude. The difference exists because TIGER was based on roads shown on USGS topographic maps, the majority of which are not considered public highways today. This overestimate of highway extent can affect a range of network operations in GIS. There is, however, reason to consider TIGER's overestimate an underestimate of the actual extent of roads in the country, as well as questioning which roads should be included in a study.

Mapping Physical Development Changes in Lagos Island Local Government Area of Lagos State Using Geospatial Techniques

The scope of the research work comprised the planning and preliminary data requirement analyses, acquisition of preliminary data such as base map, data processing and database creation process, GIS implementation using linear referencing, map creation and analyses of data as well as the presentation of results. The aim of this research is to produce a new and updated map of the study area and document changes that have occurred over time. The objectives therefore includes; obtaining an older map of Lagos Island and update its features, obtaining the GPS coordinates within the study area for geo-referencing, analyzing the land use patterns for the study area, producing a new map in a Geospatial Information System Environment and analyzing the social-economic activities within the study area. The study area of this research is <i>Lagos Island Local Government Area</i>, in Lagos State, Nigeria. It is located in the South-western part of Lagos. The Study area is Located to the extreme south of Lagos, within the latitude 6°22′- 6°25′N and Longitude 3°25′E around Atlas Cove Depot and Jetty. Methodologically, this study employed field studies where equipments such as Garmin GPS MAP 62 (Series), Data storage, manipulation and retrieval hardwares were deployed. GIS operations were carried out using softwares such ArcGIS 10.8, AutoCAD 2007 for drafting, GoogleEarth-4.2 pro Application, Microsoft Excel 2007 for the storage of easting and northing (x, y) values, for all segment points and points of interest in the study area ArcGIS 10.8 software was used for Dynamic segmentation process and GIS analysis involving spatial analysis and search while Microsoft Word 2007 was used for documentation. The result showed new spatial features such as reclaimed wet lands, new roads, buildings and social amenities located in the updated map. Finally the study by demonstrating the capacity of the use GIS and remote sensing techniques for updating of maps.

GIS and Computational Notebooks

Researchers and practitioners across many disciplines have recently adopted computational notebooks to develop, document, and share their scientific workflows - and the GIS community is no exception. This chapter introduces computational notebooks in the geographical context. It begins by explaining the computational paradigm and philosophy that underlie notebooks. Next it unpacks their architecture to illustrate a notebook user's typical workflow. Then it discusses the main benefits notebooks offer GIS researchers and practitioners, including better integration with modern software, more natural access to new forms of data, and better alignment with the principles and benefits of open science. In this context, it identifies notebooks as the glue that binds together a broader ecosystem of open source packages and transferable platforms for computational geography. The chapter concludes with a brief illustration of using notebooks for a set of basic GIS operations. Compared to traditional desktop GIS, notebooks can make spatial analysis more nimble, extensible, and reproducible and have thus evolved into an important component of the geospatial science toolkit.