Effective Water management: Moving from a database ...

CREATING A CATCHMENT MANAGEMENT INFORMATION SYSTEM (CMIS): MOVING FROM A DATABASE TO A GEODATABASE S.J. VILJOEN, E. PRETORIUS, C.H. WESSELS and O.J. GERICKE S.J. Viljoen School of Information and Communication Technology Central University of Technology, Free State President Brand Street Bloemfontein 9301 South Africa

ABSTRACT Water is a valuable resource that should be managed. It was therefore decided by the South African Government to establish Catchment Management Agencies (CMAs) that should assist in the management of water resources. Catchment Management Information Systems (CMIS) are needed to manage all the variables that have an influence on water resources. Large amounts of data should be recorded, maintained and extracted for decision making purposes. These decisions will be made after simulations and/or calculations have been performed by the system. In order to develop such a system a database should be developed to form the backbone of data management. This database will contain data from a variety of data sources and many stakeholders. The database will furthermore assist with the management (addition, deletion and updating) of data and will ensure that the integrity of data is maintained. By adding additional geospatial attributes, the database can be used in a GIS (Geographic Information System) environment and will be known as a geodatabase. This GIS environment will allow the user to perform simulations and calculations and the derived results will be used by CMAs for effective decision making.

INTRODUCTION Water is a scarce resource in South Africa which is characterized by frequent droughts, floods and erratic, unevenly distributed rainfall (3). It has become very important to manage the water resources and their quality in a sustainable and efficient way. The National Water Act (NWA) of 1998 provides a framework to protect water resources against over exploitation and indicates that water is essentially a tool to transform society towards social and environmental justice and poverty eradication. Moreover it is supposed to ensure that there is enough water for social and economic development now and in the future. Many factors have an impact on the available water resources. Hence the scope and scale of water resources policy and management is enormous and difficult to put into practice. Besides, the amount of available surface and ground water, the water use, the water quality, and the coordination of water resource management comprise environmental and social issues. Another area of concern is the collection and provision of information for water resource managers and development planners wherever water related planning takes place (7). This has led to the establishment of Catchment Management Agencies (CMAs). CMAs share the responsibility for managing water resources with the state. There exists a need to manage water resources effectively to enable CMAs to make knowledgeable decisions which will ensure that water resources are managed in a sustainable way. A relational database with all the relevant data (water oriented, environmental, social and political) should be created and eventually be converted to a geodatabase. This would allow CMAs to extract both alphanumerical data as well as spatial data from the geodatabase to make fact-based decisions. Before water management in South Africa can be discussed, a closer look at the major role players needs to be taken. First of all the Constitution of South Africa states that (9): “Everyone has the right to have access to sufficient food and water” and “an environment that is not harmful to their health or well-being” (1996), sections 27 (1.b) & 24 (a). Secondly, Act 36 of the National Water Act (NWA) states the following: “Water is a national resource, owned by the people of South Africa and held in custodianship by the state (1998)” According to the stipulations in the Constitution and the NWA the Government should ensure that everyone in South Africa has access to enough, good quality water – now and in the future. CMAs share the responsibility for managing water resources with the state (10; 8). In order to manage the water resources effectively each CMA needs to look at large collections of variables, for example environmental attributes (soil type, rainfall, evaporation, geology, temperature and water quality) and water supply attributes (industrial needs, human consumption, water demand, water leakage, purification plants). Typically, data are stored in spreadsheet programs. Although spreadsheets operate in a manner that is relatively straightforward and easy to comprehend, they were not intended as a storage tool for large data sets. To keep data organized in a spreadsheet, separate files are often created by the user to hold data from different locations, years, and types of data (e.g., catchment, stations, rivers and dams). This results in an ever increasing number of files, each of which have to be individually managed when new data are added or when new calculations are needed. The use of a Relational Database Management System (RDMS) may provide for a more flexible and locally manageable system to solve these data management problems. If suitable table structures and database design

techniques are used then decreased data storage size, decreased data retrieval times, and inclusions of new data are easily achieved. This increases data accuracy by providing one central data source, thereby eliminating the need for error prone cutting and pasting operations (4). INFORMATION SYSTEMS FOR WATER MANAGEMENT Water (catchment) management tends to suffer from a chronic failure to establish meaningful programme objectives due to the lack of data and a comprehensive information system to aid decision-making. A water authority requires information to function properly. This information is derived from data, such that the data have to be collected, processed and interpreted via information systems (IS) and information technology (IT) (6). A water authority is dependent upon this information to carry out its scientific, engineering and operational functions. The data required for water management can be categorized into three broad categories, namely, commercial data, network data, and mission specific data. Commercial data are defined as all data describing a consumer connection; network data being all data representing the infrastructure that conveys water from source to consumer including bulk conveyance and storage, distribution pipes and reservoirs, pump stations, and valves; and mission specific data all peripheral data required to satisfy a certain mission or goal. This may include water quality, return flow and effluent characteristics, cadastral and other GIS based datasets. A well-designed and structured database provides important information for improved water management (5). To achieve effective water management, a system needs to be developed to handle the data in an organized manner. This will help with the management of all data and the creation of relevant output results (Figure 1).

INPUT DATA

CMIS

OUTPUT

COMMERCIAL - Population - Towns - Municipalities

TIME-BASED RESULTS - Environmental outputs - Simulations - Predictions

NETWORK - Stations - Purification plants - Dams - CMAs

STRATEGIC PLANNING - Analysis - Estimations

MISSION SPECIFIC - Water quality - Water leakage - Rainfall - Evaporation - Temperature

DATABASE - RDMS - Spreadsheets - SQL functions - GIS-based MIS MODULES - Analysis - Water Management - Presentation & Reporting - Water Module Interfaces

PRESENTATION & REPORTING - Water demand - Water quality - Simulations - Estimations - Other

DECISION SUPPORT TOOLS - Optional - What are the scenarios? - Quick Reference Feedback

Figure 1: The movement of data in a CMIS

The creation of a CMIS will involve the following processes (as indicated in Figure 2): 1. Gather the data from all the stakeholders (Department of Water Affairs, Bloem Water, StatsSA, Weather Bureau, etc.). 2. Design the relational database by indicating which non-spatial entities (Population, Local and District Municipalities, CMAs, water boards, etc.) and water related entities (catchment, stations, rivers, dams, etc.) should be stored. Indicate how the different entities relate to one another and create an Entity Relational Diagram (ER-diagram) to provide a visual layout of the design. 3. Create the relational database by making use of a RDMS such as Oracle. 4. Analyze the relational database and determine the spatial values (longitude, latitude and altitude) of the entities used in the database. 5. Convert the relational database to a geodatabase format (by adding the necessary shape and metadata files) and use it in conjunction with a GIS. 6. Add the data into the geodatabase and test the system by creating different scenarios. 7. Go back to all the stakeholders and determine whether their needs where met and whether changes should be made to the geodatabase. 8. Implement the geodatabase and make it available to all stakeholders.

1. GATHER DATA

2. DESIGN

3. CREATE

4. ANALYZE

8. IMPLEMENT

7. STAKEHOLDERS

6. ADD DATA

5. CONVERT

G

G

G

Figure 2: Steps to create a CMIS

USING AND IMPLEMENTING DIFFERENT TYPES OF DATABASES Large datasets will be gathered and stored in one of two database management systems. Relational Database A relational database is suited for information in which relationships that allows for improved storage, maintenance, search, and retrieval can be defined. This type of database provide capabilities to enforce relationships, thereby encouraging information

integrity, improved querying and reporting, and the elimination of duplicate information. It is thus highly recommended that a relational database be used in situations where information should be frequently updated and/or frequently exported or linked to spatial information. Oracle would be best suited as DBMS due to the following reasons (1): First of all the DBMS supports the Corporate GIS Spatial Database Engine (SDE), which provides a great level of interoperability between spatial data and the database. Secondly, Oracle is suitable to manage large complex databases (this is especially important because large datasets over a period of years will be used). Thirdly, Oracle is suitable for frequent (real-time) update integration with GIS. Fourthly, Oracle will allow for the integration of all Corporate GIS applications (present and future) including desktop, wireless, intranet and internet applications and finally Oracle is suitable for implied spatial referencing in which the database content will be used to generate spatial features. For catchment management it might be necessary to store specific information that does not form part of existing GIS systems. It is therefore important to start with an analysis of all the data and to create an ER-diagram that will illustrate the interdependencies between the different entities. For example, in the Figure 3 we have a small segment of data that should be recorded in the CMIS. The blocks represent the entities (name, attributes and data types) and the lines in-between the relationships. The data will be interpreted by the DBMS in the following manner: - Provinces (contain one or more towns and contain one or more Local Municipalities). - Towns (belongs to only one province and belongs to only one Local Municipality). - Local Municipalities (contain zero or more towns, belongs to one District Municipality and belongs to one or more province). - District Municipality (contain one or more Local Municipality). Geodatabase Geodatabases contain complex data. The shape of line and area features are structured sets of coordinates that cannot be well represented with standard data types such as integer, byte, double, real, and string. In addition features (entities) are used in systems that have explicit topological relationships, implicit spatial relationships, or general relationships. The problem with a relational database is the fact that it saves alphanumerical data and does not consider the geographic side of the data. For example, if referring to a river it is necessary to record some extra information for illustration purposes, longitude, latitude and altitude. These attributes might have significant influences on the data that will be recorded and should be considered for decision making and forecasting. A geodatabase will build on the basic features of a relational database (12). Firstly, a geodatabase can represent geographic data in four ways: discrete objects as vector features, continuous phenomena as rasters, surfaces as triangulated irregular networks

(TINs), and references to places as locators and addresses. Secondly, a geodatabase stores shapes and features. By using specific GIS software the user can perform spatial operations such as finding objects that are nearby, touching, or intersecting (this aspect is important to achieve effective water management due to the fact that many variables influence each other and should be evaluated on a frequent basis to allow for accurate decision making) by referring to the framework represented by a geodatabase for defining and managing geographic coordinate systems for sets of data. Thirdly, a geodatabase can model topologically integrated sets of features such as transportation or utility networks and subdivisions of land based on natural resources or land ownership (this aspect is very important for water management). Fourthly, a geodatabase can define general and arbitrary relationships between objects and features, for example if we refer back to Figure 3 we can conclude that a town should be situated in one province and that a province has one or more towns. Fifthly, a geodatabase can enforce the integrity of attributes through domains and validation rules (by indicating the relationships between objects and assigning values to predetermined datasets will ensure that the information in the geodatabase is as accurate as possible and that the deletion of data in one part of the geodatabase does not have a negative effect on data in another part). Sixthly, a geodatabase can bind the natural behavior of features to tables that store features. Seventhly, a geodatabase can present multiple versions of the data so that many users can edit and work on the same data simultaneously.

Figure 3: ER- Diagram Geodatabases are available in two variants – personal and multi-user. A personal geodatabase is suitable for project-oriented GIS, usually smaller type projects and makes primarily use of the Microsoft ® Access database system as storage medium. A multi-user geodatabase on the other hand allows for much larger database systems with many users who can access the information simultaneously. A multi-user geodatabase will be best suited for the CMIS. Many stakeholders are involved when it comes to the management of water in South Africa and all will be linked, directly or indirectly, to the CMIS. The stakeholders can access to the geodatabase through a TCP/IP network by using ArcSDE (2, 11). The possibility to make the information available via the internet also exists.

ArcSDE will be used as database engine due to the large datasets that users will access. ArcSDE offers some valuable features. Firstly, there is no limit on the size of a database (the only limit on size will be due to the capacity of the hardware that is used to implement the CMIS, which can however be expanded at a later stage by acquiring larger storage mediums). Secondly, any relational database can be deployed (Oracle provide some unique features and will be used to create a custom geodatabase to satisfy the needs of water management). Thirdly, geographic data from UNIX or Windows NT can be served (users are not limited to a specific computer operating system platform, which will be beneficial for all the stakeholders that make use of different systems). Fourthly, data can be served to other applications such as MapObjects®, ArcIMS (Arc Internet Map Server), ArcView® GIS, and CAD client systems. Fifthly, the geodatabase can be centrally stored and administered. Sixthly, Open GIS Consortium (OGC)-compliant applications can be build. Seventhly, Structured Query Language (SQL) applications can be built to access the tables and rows in a geodatabase. An ArcGIS geodatabase will be used and forms the top-level unit of geographic data. It is primarily a collection of feature classes, object classes, relationship classes, datasets, the schema and rule base for each geographic dataset, and attribute data. Geographic data are organized into four primary types of geographic data, namely: firstly, vector data for representing features; secondly, raster data for representing images grid-based thematic data, and surfaces. Thirdly, TINs for representing surfaces. Fourthly, addresses and locators for finding a geographic position (ArcGIS 9 – Building a Geodatabase). Geodatabases are accessed through GIS-based software which allows users to add new data, retrieve data or create graphic representations of the data in a suitable map-based format. This is important because different variables can be compared/analyzed and the simulation results can be given as output to the user. RESULTS The main focus was to create a multi-user geodatabase that will make the management of catchment areas easy and transparent. The geodatabase will form the backbone of the CMIS and will assist in subsequent decision-making and environmental simulations. It is important to consider all the variables that might have a direct or indirect effect on a catchment area or that should be included in future research projects. This aspect will guarantee the sustainability of the geodatabase. A large spectrum of data (commercial, network and mission-specific) that were obtained from various sources and stakeholders were gathered and analyzed. Sybase PowerDesigner is a CASE-tool used for building applications and client/server databases. This tool was used to create an ER-diagram that indicates the different variables (entities) and their relationships to one another. Some further analysis occurred, certain mission-critical data were added and some redundant information deleted. After many discussions with the individual stakeholders and other interested parties a final version of the ER-diagram were created and this was used as a basis for the creation of the geodatabase (Figure 4).

Figure 4: Final version of geodatabase Oracle was used as DBMS because it provides the best support to the SDE and can handle large amounts of data. At this stage additional geographic attributes were added to convert the database into a geodatabase so that it can be used by the ArcGIS suite of applications developed by ESRI. All the necessary tables, relationships, domains and business rules were established and created by ArcCatalog. ArcCatalog has the same

functionality as Windows Explorer but enable the user to preview geographic data as well as metadata. ArcCatalog also provide the interface between the GIS environment and the geodatabase. With the creation of the geodatabase completed, data can be entered into it and preliminary simulations and calculations can be executed. ArcMap are used to verify the data. This does not however mean that complex simulations and results can be derived from the initial data in the geodatabase. A trial and error period should be undertaken to identify any shortcomings and to fix any erroneous data in the database. It should also be noted that it will take longer to enter large data sets (rainfall, temperature, evaporation, etc.), that expand over years, into the database. DISCUSSION AND CONCLUSION To manage the water resources of the country effectively all CMAs will need to have access to a geodatabase to make important decisions that will affect the sustainability of water in the coming years and not so distant future. Water is needed by all forms of life and is a valuable resource. The time is gone where people can just waste water. The Government, water boards, municipalities and many other stakeholders should become actively involve in the management of water. Due to the fact that there are so many variables when it comes to environmental situations a system should be put into place. The system for this is a multiuser geodatabase that allows stakeholders to supply valuable information (data) that will be used by the geodatabase and in the end reap some of the benefits by extracting data from the geodatabase or the ability to make decisions based on simulations or predictions. It is important to note that the validation of the data, at all the phases, is critical to the whole system and will determine whether the derived information will be reliable and useable. The use of range checks, limits, exception reporting and comparisons will help to identify any anomalies. REFERENCES 1.

Anon, 2003: The City and County of Denver, Corporate GIS Database Standards [online], Available from: http://www.denvergov.org/GIS/template313677.asp [Accessed May 2005]

2.

ArcGIS 9 – Building a Geodatabase, ESRI Press, California. (2004)

3.

Ashton, P.J., 2001: Walking the tightrope: The importance of water demand management in Southern Africa, The Globe Southern Africa Newsletter [online], Issue 1 Jan-Feb 2001, Available from: http://www.globe-sa.org/news101.htm [Accessed March 2002]

4.

Carleton, C.J., Dahlgren, R.A. and Tate, K.W., A relational database for the monitoring and analysis of watershed hydrologic functions: 1. Database design and pertinent queries, Computers & Geosciences, Vol. 31, Issue 4, Pages 393 – 394 (2005)

5.

Gumbo, B., Juizo, D. and Van der Zaag, P., Information is a prerequisite for water demand management: experiences from four cities in Southern Africa, Physics and Chemistry of the Earth, Vol. 28, Issues 20 – 27, Pages 828 (2003)

6.

Johnson, E.H., Integrated Water Asset Management System (IWAMS), Paper No. 99, IWA Conference, Melbourne, April 2002, Australia. (2002)

7.

Pretorius, E., Gericke, O.J., Slabbert, S.W. and Dent, M., Catchment hydrology management using GIS: case study of the Modder River Basin, South Africa. Central University of Technology, Free State, South Africa. (n.d.)

8.

Schreiner, B., Van Koppen, B., Catchment Management Agencies for poverty eradication in South Africa, Physics and Chemistry of the Earth, Vol. 27, Issues 11 – 12, Pages 969 (2002)

9.

South Africa (Republic), Constitution of South Africa – Chapter 2 – Bill of rights, Government Printer, Pretoria. (1996)

10.

South Africa (Republic), National Water Act (No 36 of 1998) of the Department of Water Affairs, Government Printer, Pretoria. (1998)

11.

Understanding ArcSDE, ESRI Press, California. (2004)

12.

Zeiler, M., Modeling our World, ESRI Press: Environmental Systems Research Institute, California, p. 12 (1999)