Open-Source Geospatial Technology for Coastal Asset Mapping and Management

Abstract

Coastal areas are highly productive in terms of natural resources and important for their strategic location. This leads to the development of industry, ports, and townships/cities in coastal areas. Therefore, many assets/ infrastructures are developed in coastal areas which are managed by respective administrations. Proper management of these assets requires a geographic information system (GIS) that can integrate and disseminate geospatial data along with ground photographs. The advancement of open-source geospatial technology enables the development of feature-rich yet cost-effective GIS applications. In the present chapter, one such web GIS framework is discussed for mapping and management of coastal assets using open-source geospatial technology.

1. Introduction

Coastal areas are bordering areas of a land surface that are close to a coastline or seashore where land and water surfaces meet. They are unique areas in terms of biodiversity and ecosystems. Coastal areas are environmentally sensitive and valuable with respect to the economy. They are extremely important to human activities, such as settlements, ports, business, and lively hood. Coastal fisheries are one of the major economic activities in coastal areas other than tourism and industry. It also provides opportunities for the generation of renewable energy. Therefore, many assets/infrastructures are developed in coastal areas which are managed by respective administrations. Coastal ecosystems provide protection against sea-level rise and tsunamis. However, natural calamities, such as cyclones and floods affect coastal regions frequently impose threats to economic and environmental assets. Proper management of these assets requires a GIS that can integrate and disseminate geospatial data along with ground photographs. The advancement of open-source geospatial technology enables development of feature-rich yet cost-effective geographic information system applications using free and open-source software (FOSS). Consequently, geospatial technology using FOSS is increasingly utilized in different sectors viz. natural resource management [1], biodiversity conservation [2], plantation and green space management [3, 4], planning of infrastructure [5]. In the present chapter, one such web GIS framework is discussed for mapping and management of coastal assets using open-source geospatial technology, including mobile apps.

Mapping of the assets is done through a field survey. GPS-enabled devices are used for collecting the spatial location of the asset. The smartphone-based geotagging application not only collects the location but also captures the asset photograph along with other associated information. The open-source Android operating system (OS) provides an excellent application programming interface (API) for developing such geotagging app that helps in systematic mapping of coastal assets and automatic generation of asset database. In the present chapter, the development process of a geotagging app using Android Studio is discussed. Once the asset data is captured in the field, the database is created. Open-source Postgres database application along with PostGIS extension provides support for spatial database management. PHP is an open-source scripting language that interfaces the database to retrieve information and passes them to the client application. The client application developed using HyperText Markup Language (HTML), JavaScript, etc. enables in generating dynamic web pages to send and receive user queries and replies respectively from the server. In the present chapter, the development framework of a WebGIS application involving open-source geospatial technologies is discussed.

A brief introduction of WebGIS, including its characteristics and components, is given in Section 2. Section 3 introduces mobile applications in the context of location-based services. The methodology is described in Section 4 whereas the results are discussed in Section 5. Finally, conclusions are drawn in Section 6.

2. WebGIS

GIS system includes computer hardware, software, and applications to capture, edit, analyze, manipulate, and visualize geo-referenced data. WebGIS is an advanced form of GIS available on the web platform where the exchange of information takes place between a GIS server and a client (mostly browser-based) application running on a mobile or desktop.

2.1 Characteristics of WebGIS

A diverse set of analytical functions are offered by GIS beyond mapping. WebGIS extends the potential of GIS to a wider audience and helps in the decision-making. Some of the important characteristics of WebGIS are listed below:

• It serves a large number of users simultaneously

• Runs on browser and supports multiple platforms and operating systems.

• Follows unified updates.

• Easy access to map and satellite imagery for different applications.

• Available in customized dashboards with user-friendly interfaces.

2.2 Components of WebGIS

WebGIS allows the dissemination and analysis of geospatial data over the web. Components of WebGIS include (i) database server, (ii) GIS server, (iii) application server, and (iv) client. Figure 1 shows the architecture of WebGIS where each component is connected. It is a three-tier architecture. The first and second tires include the client (Browser) and application server respectively, whereas the GIS server and the database server reside in the third tier. The communication between these components is performed via Hypertext Transfer Protocol (HTTP) and the format of the response can be an HTML, binary image, XML (Extensible Markup Language), GML (Geography Markup Language), or JSON (JavaScript Object Notation).

Figure 1.

WebGIS architecture.

The client accesses the WebGIS application hosted in the application server through HTTP requests. The WebGIS application provides a customized interface that includes functionalities viz. display, overlay, query, and analysis. The client requests are analyzed in the application server and accordingly, requests are sent to either/both GIS server or/and database server. On a successful query, responses are sent to the application server from the database and/or GIS server. Finally, results are presented to the client in customized form by the application server through the HTTP response. Brief functionalities of each of the WebGIS components are described in the following subsections.

2.2.1 Database server

A GIS includes spatial and aspatial data which are stored in a database. The database is suitable for large datasets with several features and provides an efficient mechanism to store, query, analyze, and update these data [6]. Database server communicates with the GIS server and application server for providing spatial and aspatial data as per their requests.

2.2.2 GIS server

The GIS server is software that creates web services using spatial data for GIS applications. Web service runs on the GIS server and performs some actions in response to a client request. To facilitate the exchange of geographic data across the web, the Open Geospatial Consortium (OGC) has defined open specifications for GIS web services. Different OGC compliant services include the web map service (WMS) and web map tile service (WMTS) for requesting maps, the web feature service (WFS) for requesting vector feature geometries and attributes, the web coverage service (WCS) for raster data requests, and the web processing service (WPS) for spatial data processing operations.

2.2.3 Application server

The application server hosts the WebGIS application that accepts clients’ requests and processes them and provides the output in customized form. Different APIs and libraries viz. OpenLayers and Leaflet are used to develop the WebGIS application that consumes web services. API is an organized set of programming components that can be used to develop applications using a particular language. The application handles the details of all the web service requests occurring in the background and provides an intuitive user experience. In WebGIS application maps are often produced by combining multiple web services as layers. The term “mashup” refers to describe such maps created from multiple web services [7].

2.2.4 Client

Client refers to a computer or other device that requests information or processing from a server. The client accesses the WebGIS application hosted in the application server through the browser via the Internet. Each time an action is performed at the client, the request is sent to the application server. On successful processing of the request, the result is displayed at the client end in a customized form in the WebGIS application.

In spite of having advantages over standalone GIS, WebGIS have several challenges viz. security, data quality, performance, poor network connectivity, and maintenance.

3. Mobile application for location-based services

The geographical location of an object along with its description is an important aspect of mapping. Objects are mapped in the field using traditional tools and methods that have their own limitations. In recent years, digital methods with new technologies are gaining significant interest and popularity for field surveys and mobile-based mapping is one of them. Smartphones and tablets integrated with Global Positioning System (GPS) receiver provide a convenient way of recording location as well description of observations. Hence, in the present section, a few important technological tools/functionalities are described briefly that help in developing mobile applications for location-based services.

3.1 GPS module

GPS, a satellite navigation technology, provides the geolocation information of an object and is mostly used in the location-based mobile app. The location accuracy of recent GPS technology is within a few meters.

3.2 Cellular ID

Cellular identification is unique for any device. It enables in getting the approximate location information of the device from the cellular tower. It is an essential component of geolocation in the absence of live data from the mobile device.

3.3 Geofencing

A geofence is a virtual boundary set up around a geographical location. Geofencing is a location-based service in which an app uses GPS or cellular data to trigger certain predefined actions when a mobile device enters or exits a geofence.

3.4 Map functionalities

The map is an important element that supports the display and analysis of location information. In addition to the display of map and satellite view, some significant functionalities of map elements include routing/navigation, geocoding, measurement of distance/ area, etc.

4. Methodology

Coastal asset mapping and management system involve two subsystems, the first one is mapping and the second one is management. In this section, the methodology for designing and developing the total system is discussed using open-source geospatial technology.

4.1 System architecture

The mapping of coastal asset is carried out using location-based services of the mobile device whereas the management of assets is implemented through WebGIS. The overall system architecture is given in Figure 2. The mobile application is developed to collect coastal asset data in the field. This data includes field photos as well as asset information. Once the data is collected by the app, it is saved on the device. Subsequently, the data is sent to the database server via the application server through the Internet. GIS server hosts the WMSs related to base map layers. The database server serves the spatial and aspatial data to the GIS server and application server depending on the requests. The development methodology of each of the components using open-source tools and software is described in the following subsections.

Figure 2.

Overall system architecture.

4.2 Design and Development of Mobile application

The most popular open-source mobile-operating system is Android. Hence, in the present chapter, the development of an Android-based mobile application is discussed using Android Studio. Android Studio is the official integrated development environment (IDE) for Android and contains features that are required to build an Android app. An IDE is software that combines common developer tools into a single graphical user interface (GUI) for building applications. Some important features of Android Studio include visual layout, APK analyzer, intelligent code editor, fast simulator, flexible build system, etc. that accelerates the development process and helps to develop quality applications for Android devices.

Since the mobile, as well as the WebGIS, shares a common database, the database is designed first. The main objective of the mobile app is to collect coastal asset information. Therefore, the asset table is created using the fields viz. asset name, asset type, locality, latitude, longitude, date/ time stamp, and collector’s information.

The Java Programming Language, Android software development kit (SDK), and SQLite Database were used for developing the application. Java is a general-purpose programming language that is class-based, object-oriented, and designed to have as few implementation dependencies as possible. Android SDK, a collection of software development tools and programs, is used to develop new applications for devices running the Android operating system. Android apps can be developed using Kotlin, Java, and C++ languages using the Android SDK. The SQLite is an embedded SQL database engine that is used here for storing the collected survey data in the mobile device through the mobile app.

4.3 Design and development of WebGIS application

The Coastal asset WebGIS application may include user authentication to ensure secure data access. The user interface of the application is designed as a dashboard. The main application page contains a map with elements viz. legend, table of content, overview map, and scale bar. Different GIS functionalities viz. Navigation and Measurements are developed as different tools and combined under the “Tools” menu. All the tools and map elements are made collapsible to facilitate effective map visualization.

4.3.1 Preparation of map layers

Coastal asset mapping and management is a special kind of GIS application. The base map may include layers viz. road and rail network, population information, land use/land cover (LU/LC), administrative boundaries, drainage, and water bodies. Remote sensing and GIS techniques are utilized for the generation of various thematic resource maps in conjunction with ancillary data. Quantum GIS (QGIS) [8] is a free desktop GIS software that can be used to generate these spatial layers. QGIS supports both raster and vector layers allowing users to analyze them for spatial map generation. External WMS and WFS are also supported in QGIS [9].

Remote sensing satellite data, such as CARTOSAT and LISS-IV, may be integrated with the GIS environment to extract information related to natural resources and generate thematic layers. These utilitarian types of maps serve the purpose of planning and decisions making.

4.3.2 Generation of database server

Since the mobile and WebGIS application shares a common database the design of the database should be performed at the beginning before the actual development starts. The structure of the coastal asset data table is generated along with its field definitions and data types. This table is used to save the asset records captured through the mobile app. The same table is used by the WebGIS application for the display and analysis of coastal assets.

A spatial database is required to store and utilize the asset data in the web environment. PostgreSQL/PostGIS is a powerful reliable and stable open-source database [10, 11] and is used for this purpose. It supports most of the major operating systems viz. Linux, UNIX, and Windows for managing spatial/aspatial data. PostGIS extension of PostgreSQL provides support for geographic objects. This enables the performance of spatial queries in PostgreSQL. Hence, the coastal asset database is created in PostgreSQL/PostGIS where the asset table is generated. Subsequently, the other geospatial layers are incorporated in the coastal asset database one after another.

4.3.3 Formation WMS

Once the database is prepared, the spatial layers are converted into Web Map Service (WMS), to facilitate spatial data sharing over the Internet. The open-source Java-based GeoServer [12] provides the platform to share, edit, and display geospatial content in the web environment. It accesses data from any major spatial data source viz. PostGIS, ArcSDE, Oracle, and DB2 and publishes those using open standards. GeoServer enables very quick and easy map generation using the free java-based mapping library “OpenLayers.”

4.3.4 Development of client web application

The interactive WebGIS application for the management of coastal assets is developed using HTML and Java scripts, while OpenLayers [13] mapping library is used to develop geospatial functionalities. OpenLayers enables the development of feature-rich WebGIS applications by putting a dynamic map on the web page [14]. Tiled layers can be rendered using OpenLayers from OGC complied sources viz. open street map (OSM), Bing, and MapBox. A range of vector data formats, including GeoJSON, TopoJSON, KML, and GML, is supported by OpenLayers. Operations, such as map rendering, interactive drawing, and editing can be performed by OpenLayers without using an additional plug-in at the client end.

PHP (Hypertext Preprocessor) [15] is used to query the database and fetch results as per the user’s requirement. PHP is a fast and flexible general-purpose scripting language that can be easily embedded in an HTML page. Hence, it is very popular and useful in web-based application development. It is used as server-side script to interface the database from the WebGIS application.

The query results fetched from the database are dynamically managed using AJAX (Asynchronous JavaScript and XML) [16] web development technique. It asynchronously sends the request and retrieves data from the server in the background without reloading the web page. To achieve this, it uses a group of existing web technologies together, including HTML, Cascading Style Sheets (CSS), JavaScript, Document Object Model (DOM), XML, and the XMLHttpRequest object. The dynamic results are parsed and analyzed using the jQuery JavaScript library [17]. The feature-rich jQuery library simplifies event handling and AJAX in the WebGIS application. CSS dictates the appearance of HTML elements of a page and hence is used to develop the look and feel of the user interface of the present application.

5. Results and discussions

The entire system contains two major applications one is the mobile app for coastal asset data collection and another is WebGIS application for data visualization and management. The functionalities of the asset data collection app are described in section 5.1 while the WebGIS functionalities are given in Section 5.2.

5.1 Mobile app for coastal asset data collection

The mobile application starts with a user profile screen. It takes the user’s information viz. name, email id, and phone number, and validates them (Figure 3a). Information once entered is stored for subsequent use, however, at the beginning of the next use, the user can update them. Upon receiving the valid user information, the app proceeds to the main activity (Figure 3b). Here, options are provided to input information and take a picture related to coastal assets. The current latitude and longitude positions are captured by the GPS receiver of the mobile phone. Finally, the record consisting of all these data can be sent to the server along with the current date and time stamp using the “Send” button. The captured information can be saved in the local device using the “Save” button. The Exit button enables exiting the application. The “Records” button enables viewing and editing of saved records. The mobile app also enables the user to visualize the sent records using the “Map” button.

Figure 3.

Mobile app (a) home screen, and (b) main activity screen.

5.2 WebGIS functionalities

Once the captured record is sent to the centralized server, the web application displays those records on the map. The display of the map is shown in Figure 4 where the coastal area of the state of West Bengal, India is shown. The Bhuvan [18] WMS is used for the display of the base map and satellite imagery. The satellite view shows the high-resolution satellite image of the area.

Figure 4.

Map display.

The map also shows the scale bar as well as the overview map at the bottom left and the bottom right corner, respectively. Here three asset locations are plotted using blue markers which were collected using the mobile app. Different markers/colors may be assigned to display different types of coastal assets on the map viz. administrative, financial, educational, industrial along with the proper legend.

Another important functionality of the WebGIS is overlay where individual map layers (here WMS) are overlaid on the base map. Users can control the overlay through the content window that contains all the spatial layers available in the application. Figure 5 shows a sample content window that enlists administrative boundaries viz. block boundary, district boundary, road, drainage, land use/land cover. Users can add or remove these layers as and when required. The zoom-in button is placed next to each layer which enables to zoom the map to the layer extent.

Figure 5.

Map overlay with content window.

The map navigation tools are kept in a toolbar as shown in Figure 6. This includes functionalities, such as previous view, next view, zoom-in, zoom-out, zoom to full extent. In addition to this map, navigation can be controlled using mouse scroll and left buttons.

Figure 6.

Map navigation tools.

Measurement of distance and area on the map is carried out using the respective tools. Figure 7(a) and (b) depicts the usage of area and distance measurement tools respectively on the satellite image.

Figure 7.

Measurement tool for (a) area, and (b) distance.

Search is an important functionality of the GIS application. Search on the coastal asset layer can be performed by type/name/location. Search results in the display of assets that matches the criteria along with statistics. The output can be further displayed using charts. Spatial as well as aspatial queries also can be implemented depending upon the user’s requirements. The proximity analysis enables to identify assets in a given buffer distance of a selected location in the map. In addition to it, the user can select a particular category of the asset to the given proximity of a location. Figure 8(a) shows the location of health facilities (by the red marker) available in the 5 km proximity from the location denoted by the black marker. The proximity tool is shown in Figure 8(b). The map “onclick” functionality shows the pop-up window to provide further details of an asset along with the ground photograph as given in Figure 9. These data were captured and sent through the mobile app and subsequently are available in the WebGIS application in near real time.

Figure 8.

Proximity analysis.

Figure 9.

Map ‘on-click’.

Routing comes under network analysis where the road network is used to get route direction for a given pair of source and destination locations chosen by the user. The route direction tool and the map output are shown in Figure 10.

Figure 10.

Route direction.

6. Conclusions

In recent years, geospatial technology is effectively utilized in the management of natural resources and spatial infrastructures [19, 20]. Compared to conventional methods, this technology is efficient and hence is widely adopted in different applications across the world. It has become more popular and affordable among the stakeholders due to the availability of FOSS. In the present chapter, an open-source framework is discussed for coastal asset mapping and monitoring using geospatial technology. This enables fast capture and analysis of coastal asset information in near real time in a cost-effective manner. Mobile app-based asset data collection involves minimum human interaction that leads to more accurate data entry and less error. The system provides authenticate and reliable data access mechanism. The WebGIS application is accessible by a large number of stakeholders without any financial investment at the individual level except the Internet connectivity. It has great customization capability [21] to encode the complex business logic that enables effective decision-making even by non-GIS professionals.

Acknowledgments

The authors acknowledge the Bhuvan portal and the team for providing supporting map functionalities.

Conflict of interest

The authors declare no conflict of interest.

Other declarations

Results are demonstrated using synthetic data.