Development of Geoweb application using Open Source Technology: An innovative approach for disaster mitigation and management

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1 Development of Geoweb application using Open Source Technology: An innovative approach for disaster mitigation and management Harish Karnatak Reedhi Shukla National Remote Sensing Center (ISRO) Hyderabad (Andhra Pradesh), INDIA Hariom Singh Sameer Saran Abstract - Internet GIS technology has recently triggered into all the decision making process due to the recent advances both in broadband & wireless communication and internet technology. Today the GIS web portals provides a user friendly interface to access theme based distributed resources and data services. Therefore a single GIS services may not be sufficient to address the requirements of all kind of target users. The development of interoperable GIS application by consuming the web services from different sources gives a unique platform for planning and decision making. Under the present study, we have used Open Source GIS solutions at server end to develop mashup application by consuming the web services from various web portals. In addition to that a centralized repository of Flood Hazard zonation map of Assam state, Land Use Land Cover(LULC) integration with Flood Hazard map, Flood Hazard zonation map at village level etc are being used. The centralized and distributed dataset are disseminated through a rich GUI based Web GIS application using OpenLayer and GeoExt. Further Geoserver is used as a GIS server while PostgreSQL with PostGIS are used as a Geo-RDBMS, PHP is used as web application development and Apache web server is used for web publishing. The GeoWeb application also provides the functionality for vector based Geo-processing based on OpenLayer WKT parser and implemented for Buffer, Union, and Intersection operation. The functioning of OpenLayer WKT parser is to publish spatial data on the OpenLayer map when spatial data are organized as WKB in PostGIS. Keywords: Internet GIS, Open Source GIS, web services, LULC, vector based Geo-processing. 1. INTRODUCTION Geographic information is collected for geographically dispersed locations and archived, processed, and maintained by numerous organizations spanning multiple application objectives [1]. As the use of the Internet became more widespread, there came a remarkable growth in Internet GIS, especially for the dissemination of GIS functions and geospatial data. The advantage of the Internet, i.e. global and real-time accessibility, ensured its potential as an important medium for the dissemination of GIS functions and data [2]. It promoted the participation of the public and customers, and resulted in the increased scale and profitability of many GIS projects [3]. Internet GIS can provide better solutions to problems than traditional GIS, which was hindered by its closed architecture [4]. With the recent advances in broadband and wireless communication technologies as well as the dramatic increase in internet technology it is promising to extend further the reach and range of GIS user working in offices and laboratories in the field or at home would lead to the development of internet GIS or web enabled GIS [5]. The Internet technology as a digital communication medium enhances the capability of GIS data and software application by making them more accessible and reachable to wider range of users, planners and decision makers. Today the GIS based web portals provides a centralized and uniform interface to access the distributed and heterogeneous resources and data services [6]. Most of the web GIS based portals available in Internets are designed for specific theme and are targeted to specific class of users. A single GIS service may not be sufficient to address the requirement of all kind of target users. The positive development in this emerging area is adoptions of common international standards published by Open Geospatial Consortium (OGC) for GIS data and services. GIS services defined by the OGC are part of a larger effort to build distributed systems around the principles of Service Oriented Architectures (SOA). Such systems unify distributed services through a message-oriented architecture. Web Service standards are 1 P age

2 a common implementation of SOA ideals [7]. As disaster management work usually involves a large number of different agencies working in different areas, the need for detailed geographical information in order to make critical decisions is very high. By utilizing geo-information technologies, agencies involved in the response can share information through databases in the form of digital maps, products and services at one location. Without this capability, disaster management personnel have to access a number of departments and their unique data. Most disasters do not allow time to gather these data. The internet or web based GIS technologies by integrating the DSS tools can provides a mechanism to centralize for necessary analysis and visual display of critical data/ information during an emergency. The main objective of this study is to suggest a new development model for dynamic and interoperable Internet GIS applications in the application of disaster management using the open source GIS solutions. In this study, the relevant technologies for Internet GIS development were thoroughly reviewed, and then a new development model was designed and successfully tested. 2. PREPARATION OF GEO-SPATIAL DATA Through Decision Support Centre (DSC), NRSC/ISRO has taken up development of Flood Hazard Zonation Maps using satellite data towards Disaster Risk Reduction, under ISRO-DMS Programme. Towards this, as a first step, NRSC has generated Flood Hazard Zonation Maps for Assam state of India based on the analysis of 10 years of multi-temporal satellite datasets acquired during the flood seasons of , Flood Hazard layer is derived. Based on frequency of inundation, the flood hazard is categorized into 5 classes -Very high, high, moderate, low and very low. About % (22.21 lakh hectares) of land in Assam State is subjected to flood inundation during Out of total flood affected area (22.21 lakh hectares), about 3.53 lakh hectares of land i.e % falls under high to very high flood hazard categories (i.e., subjected to flood inundation at least 7 times during ) ( As per the published literature in Flood Hazard Zonation Information service ( the major steps involved in preparation of flood hazard zonation maps: to programme the satellite data during near peak situations. Satellite data was also programmed and procured during progression and recession of the flood wave for studying the impact of the flood. B. Spatial Data Rectification The acquired satellite datasets were rectified to a defined projection system for integration with database layers. C. Preparation of Flood inundation layer Using image processing classification algorithms water layer was extracted from the satellite data and integrated with the pre-flood river and water bodies layer to derive flood inundation layer. D. Preparation of Annual Flood Layer The flood inundation layers generated for different flood waves in a calendar year were integrated to generate the maximum flood inundation extent observed in that year. E. Preparation of Flood Hazard layer The maximum flood inundation layers corresponding to various years ( ) were integrated for assessing the frequency of inundation and subsequent generation of hazard layer. F. Database integration The hazard layer was further integrated with the database consisting of administrative boundaries, landuse/landcover, infrastructure, etc. for impact assessment and statistics generation. 3.1 DEVELOPMENT OF INFORMATION SERVICES The geo-spatial data on flood hazard zonation and other geo-spatial data generated under ISRO-DMSP programme are published into internet domain with various GIS tools for decision analysis and information extraction. The software development for this information service is done using open source GIS solution for web application. The general software system architecture is shown in Fig 1. A. Satellite data Acquisition Satellite data from Indian Remote Sensing Satellites (IRS) and microwave satellite data from Radarsat satellite was acquired during the floods in Brahmaputra since The water levels observed at different gauge stations were closely monitored during floods and attempts were made 2 P age

3 Figure 2. Home page of flood hazard zonation information service Web Browser Client HTTP Web Services Client WMS+WFS The home page of flood hazard zonation information service provides various technical documents with detailed methodology adopted as a hyperlink available in top menu bar. Web GeoExt Ext JS OpenLayer API Application End Figure 1. Software System Architecture Geo Data The tools and technologies used in the development of flood hazard zonation information services are listed in table 1. The online district atlas provides various utilities to the users Fig 3. The statistical analysis with crop area damage assessments, inundation area statistics, flood hazard zonation wise area distribution are available for user defined administrative areas viz Online statistical analysis of spatial features Fig 3 S. No. 1. The ready to printable maps are also available for download Fig 3 S. No. 2. The list of affected villages can also be visualized Fig 3 S. No. 3 and searched using an AJAX based search engine Fig 3 S. No. 4. S. No. Technology Purpose 1 PostgreSQL Database 2 POSTGIS Spatial Database gateway 3 Geoserver GIS server for publishing OGC web services 5 PHP Programming environment for application server 6 OpenLayer Development of Geoweb 2.0 application 7 GeoExt Rich web GIS GUI 8 Apache Web server Table 1. Used tool and technology CUSTOMIZED GEOWEB APPLICATION RESULT AND DISCUSSION The Geoweb application on flood hazard zonation of Assam state is accessible using URL: Few of the outputs as a screen shot image are shown below: Figure 3. Various utilities available under online District atlas The GIS shell of this information service provides a very user friendly GUI (Graphical user interface) for various online GIS operations Fig 4. Figure 4. GIS Shell of Information Service The important components of GIS shell includes layer 3 P age

4 control, legend, navigation toolbar, tool for linking of attribute data with spatial features, dynamic query builder, WMS consuming utility for live servers, spatial filter, layer transparency tool (similar to layer swipe utility) etc. 3.3 WEB BASED GEO-PROCESSING METHODOLOGY that are within a specified distance of a point, line or polygon. For example, you might use a buffer to create a circular area encompassing 56 km around a road defining this region to find villages as shown in Fig 6. Customized GIS applications allow the buffer distance to vary per feature. The vector based Geoprocessing (Buffer, Union, Intersection) has been achieved by using capability of POSTGIS where industry standard SQL is used as a communication medium with RDBMS for GIS data. By using SQL the vector based analysis has been done Fig 5 Configuration WKB Application Database PostGreSQL + PostGIS GIS - PHP Geo WMS/WFS OpenLayer API WKT Web GIS Application Web Application Deployment Web (Apache) Figure 6. Line Buffer and result UNION ANALYSIS Union is another Analysis tool used to perform overlay analysis on the basis of features in the vector data. Union builds a new features class by combining the features and attributes of each feature class as shown in Fig 7. WMS/WFS Network Infrastructure/ Firewall etc Enterprise GIS Clients C1 C2 Cn Web based Geoprocessing Figure 5. Geoprocessing Methodology The role of POSTGIS is it adds support for geographic objects to the PostgreSQL (object-relational database). In effect, PostGIS "spatially enables" the PostgreSQL server, allowing it to be used as a backend spatial database for geographic information systems (GIS) [8]. The vector based Geoprocessing is attempted based on OpenLayer WKT Parser and implemented for Buffer, Union, & Intersection operation. The functioning of OpenLayer WKT parser is to publish spatial data on the OpenLayer map when spatial data organized as WKB in PostGIS. 3.4 GEOWEB APPLICATION FOR WEB BASED GEOPROCESSING BUFFER ANALYSIS A GIS Buffer is a proximity analysis used to create polygons based on a specified distance from the original geometrical feature. The output is a larger zone or region that surrounds and encompasses the feature. The output of a Buffer is often used to define or determine any features Figure 7. Intersection of Lines and Polygons The process application provides single features by combining multiple features and its corresponding attribute. This customized application can perform the functionality to union not only in proximity but also remote feature class INTERSECTION ANALYSIS Intersect is one of the Analysis tools used to perform overlay analysis on vector feature. This tool builds a new feature from the intersecting features common in both feature. In other words - that portion of geometry A and geometry B that is shared between the two geometries. If the geometries do not share any space (are disjoint), then an empty geometry collection is returned. 4 P age

5 3.5 Conclusion and Future Direction The web GIS based application using open source GIS has been developed & demonstrated for different data set. The OGC web service specification are implemented WMS/WFS for inter operable GIS. The Interoperability in data& information is very important when we are developing any multi-user GIS application. The web serviced base architecture provides a framework using distributed GIS technology for disaster mitigation and management. The web services specification demonstrated in this study are not specified to any application or area. Web services can be consumed in web browser based application and also in thick client GIS software like Quantum GIS, Open Jump, and ESRI ArcGIS etc. Web serviced based architecture is one of the best for sharing and dissemination of GIS data. The Geoprocessing capability demonstrated in this study using SQL will be very useful in many areas of national resource management. The Geoprocessing in web GIS environment is emerging area where GIS researcher are trying to build a complete solution in web environment for solving any GIS based decision problem. The OGC initiative for web processing service (WPS) is pioneering effort in this direction. The application developed in this study is for only a technology demonstration purpose. The more generic tools for various Geoprocessing can be customized with its application in any specific area. The spatial decision support system (SDSS) and expert system can be developed to solve GIS based decision problem. This application can be enhanced to provide a complete GIS solution in web browser environment. REFERENCES [1].GOODCHILD, M.F., EGENHOFER, M.J., FEGEAS, R., and KOTTMAN, C., 1999, Interoperating Geographic Information System (Norwell, MA: Springer). [2].SU, Y., SLOTTOW, J. and MOZES, A., 2000, Distributing proprietary geographic data on the World Wide Web UCLA GIS database and map server. Computers & Geosciences, 26, pp DOI /s [7]. Sayar. A., Integration AJAX Approach into GIS Visualization Web Services, ICIW 06 Proceedings. [8]. AUTHORS PROFILE Dr. Harish Karnatak: Working as a Scientist SE at Indian Institute of Remote Sensing, ISRO Dehradun. He is PhD in computer science and having more than 10years of experience in Geoinformatics and software development for GIS. His area of specializations is enterprise and distributed GIS, web GIS, SDSS, spatial DBMS and open source GIS development and implementation. Mr. Hariom Singh is M.Tech in Spatial IT.Presently working as Research Scholar at Geoinformatics Division of Indian Institute of Remote Sensing, ISRO, Dehradun INDIA. His area of interest includes Distributed GIS and Spatial Database Management System, RDBMS. He is working on national level operational /research projects on Web/Distributed GIS using Open Source GIS solutions Ms. Reedhi Shukla: Working as a Scientist SD at National Remote Sensing Centre, ISRO Hyderabad. She is B.Tech in computer science with specializations in software development for GIS (web and desktop based). Dr. Sameer Saran is postgraduate in Physics and is Doctorate in the field of Geoinformatics. He is presently Scientist at Geoinformatics Division of Indian Institute of Remote Sensing, ISRO, Dehradun INDIA. He is working on various projects of Distributed Web GIS Services, Geospatial Modeling, Spatial Data Mining, Geodatabase, Spatial Decision Support System and Multi-criteria decision analysis. His other field of interest includes Microwave Remote Sensing, Process Based Modeling and Open Source Software s. [3].CARVER, S., 2001, Public participation using web-based GIS. Environmental and Planning B: Planning and Design, 28, pp [4].DAVID, J.A., KERRY, T., ROSS, A. and STUART, H., 1998, An exploration of GIS architectures for Internet environments. Computers, Environment and Urban Systems, 22, pp [5]. Zhong-Ren Peng, Ming-Hsiang Tsou, (2003). Internet GIS: Distributed Geographic Information Services for the Internet and Wireless Networks, ISBN: m March [6]. Karnatak H.C, S. Sameer, K. Bhatia and Roy P.S., 2007, Multicriteria Decision Analysis in Web GIS Environment, Geoinformatica, (2007) 11, pp: : Springer Science Publication 5 P age