In water management not only daily planning and operational water management
is of great concern, the maintenance of water systems (embankments, structures,
canal systems et cetera) is essential. Regularly safety tests have to be
drawn up on components of the water system. The actual condition of each
component has to be compared with the requirements. Therefore, the actual
conditions of the water system have to be monitored continuously to gain
insight into necessary maintenance.
Much information has to be gathered and stored before any calculations for the determination and budgeting of the necessary maintenance can be made. The responsible authorities in the Netherlands have already stored much information in automated information systems. Alphanumerical information on land registration is mainly stored on the AS-400 platform. For the graphical information mostly AutoCAD is used. Information on the conditions of the water systems was mainly stored in paper archives or local databases. Therefore an application was built for structured, automated, user-friendly registration of management information that could use the existing automated information. Advantage was taken of the use of a geographic information system because lots of graphical data (AutoCAD) had to be linked to alphanumerical data (dBASE, AS-400).
In water management not only operational water management is of great
concern, the maintenance of water systems (embankments, structures, canal
systems et cetera) is important as well. According to Dutch legislation
regularly safety tests have to be drawn up on components of the water system.
The actual condition of each component has to meet the requirements. Therefore,
the actual conditions of the water system have to be monitored continuously
to gain insight into necessary maintenance.
In the Netherlands a new Act on flood protection came into force in
January 1997. This act obliges water managers to test the primary structures
on safety periodically. Therefore, the country is subdivided into dike-ring
areas. A dike-ring consisting of dikes, dunes, water-retaining works and/or
higher ground surrounds each area.
Testing a component/element on safety can be seen as comparing the actual conditions with the initial design criteria (safety-norms/standards). Requirements are set for loading and acceptable statistical return periods of the exceedence of the water level that a dike-ring component should withstand are laid down. These requirements apply to crest level, berm width, condition of components et cetera. The statistical return period varies for 10,000 years (for dike-ring areas subjected to see-floods) to 1,250 years (for dike-ring areas subjected to river-floods). In water quantity management similar equations can be made. Here canals and structures must fulfill certain requirements in gauge-control, water discharge, water supply, environment, recreation, shipping access, road connection, transport, agriculture, fishery and landscape.
A lot of data has to be gathered and stored before any calculations can be made. Many organizations (national and local government, engineering firms) and computational models are using the same kind of information. This information is stored in several kinds of databases. The integration of these databases faces a number of complex problems, like the definition of variables, objects and the specific dimensions of the variables. For that reason standardization of description of this information is indispensable. The easiest solution is to agree upon a dictionary describing the essential terminology. Therefore, the Union of Dutch Polder-boards has set up a dictionary of water system information. This dictionary gives a classification of all objects with their attributes used for surface water modeling. These objects are categorized in fields of area, measurement, pipe, surface water, dike, structure et cetera. Every categorized (entity) object has its own code, graphic symbol and several attributes that are coded as well. When a database is structured in this manner, it is easy for an application, which also uses this classification, to retrieve the desired data for their variables. Along with the classification project in the Netherlands there is an attempt by STOWA, a foundation for applied research in water management, to define a digital exchange format. The digital exchange format is based on NEN 1878 (comparable to National Transfer Format in England) and NEFIS (comparable to Hierarchical Data Format). At this moment NEN 1878 is only a definition that describes how to write (geo-)graphical and alphanumerical data into an ASCII file. An ASCII file has the disadvantage that the data can only be read sequentially. Therefore this format is only suitable for off-line exchange of mainly (geo-)graphical data. Another disadvantage of NEN 1878 is that there is yet no standard interface written that allows users to store data in the defined format. The main advantages of NEFIS regarding to NEN 1878 are that the data is self-describing and can directly be accessed (binair format). Therefore NEFIS is very suitable for on-line alphanumerical (more dimensional measurement) data exchange. This standardization process gives possibilities for the exchange of information between several applications. (Figure 1)
In July 1993 one Dutch polder-boards (Hoogheemraadschap van de Alblasserwaard
en de Vijfheerenlanden ) and Delft University of Technology (faculty of
Civil Engineering) started to develop an automated geographic information
system for dikes named GISWAK. This project aimed to develop a structured,
user-friendly registration of management information on PC-level. Then
however there was no standard dictionary for water management. Therefore
a data model had to be created in which information, required for the testing
of dikes, could be stored. The first data model of GISWAK was, among other
sources, used for the development of the standard dictionary. To meet the
requirements of the final standard dictionary, the structure of the latest
data model of GISWAK is slightly changed. In 1995 an alliance of six Dutch
polder-boards started to develop a geographic information system for water
quantity management, named GISWAB. The functionality of this application
is fully based on the application GISWAK.
The responsible authorities have already stored much information in
automated information systems. Alphanumerical information on land registration
is mainly stored on the IBM AS-400 platform. For the graphical information
mostly AutoCAD is used. Initially, information on the conditions of the
water systems was stored in paper archives or local databases. Therefore,
an application was built for structured, automated, user-friendly registration
of management information that could use the existing automated information.
Advantage was taken of the use of a geographic information system because
a large number of graphical data (AutoCAD) had to be linked to alphanumerical
data (dBASE, AS-400).
Some of the main concerns, regarding selection of software and hardware, that the water-boards had, were: cost, simplicity, flexibility and the use of existing data. Since the water-boards were using a PC-platform and AutoCAD the evaluation of available PC-based GIS packages rapidly lead to selection of ArcCAD from Environmental Systems Research Institute, Redlands, California (Esri) as the preferred choice. ArcCAD is a GIS that is fully integrated in AutoCAD and based on ArcInfo, the world leading GIS. Another reason for adopting ArcCAD is the availability of ArcVIEW, i.e., a low-cost application that enables to visualize, explore, query and analyze data (created in ArcCAD, AutoCAD, ArcInfo et cetera) geographically. There is a clear separation between input and use of the information. Therefore, two types of applications have been developed: an 'input-part' in ArcCAD and a 'use-part' in ArcVIEW.
The data models of GISWAK and GISWAB (125 object-classes and 800 attributes) are subsets of the total data dictionary (275 object-classes and 1300 attributes). The classifications (object-class) which can be defined in GISWAK and GISWAB are grouped as follows:
Each object-class is modeled in a graphical, geographical and alphanumerical way. The graphical model of an object is a 2-dimensional (x-y) AutoCAD-entity. All objects of the same class are grouped in a layer. Colors, line types and symbols can be standardized from within the application. Afterwards a theme is defined for each layer. The definition of each theme is set in the data dictionary. The water-board territory, in general a dike-ring, is divided in several small districts (such as dike compartments, drainage areas and irrigation areas) modeled in separate AutoCAD drawings, primarily to prevent excessively large datasets.
Only some specific (general) information of the total water-board territory is stored in an overall survey drawing. Most information is stored in situation drawings (small districts). Beside these kinds of drawings also profiles are distinguished. In profiles only twodimensional (x-z and y-z) graphical information about shape, height and underground is stored.
The input part of GISWAK and GISWAB is written in AutoCAD/ArcCAD using AutoLISP. The objective of the input applications is to provide tools to the user to register management information in a structured and user-friendly way. Therefore the ArcCAD environment is adjusted and customized for water managers. Because there is hardly any knowledge about ArcCAD within the water-boards, a graphical user interface was created that gives all ArcCAD functionality hidden behind AutoCAD commands. After opening a new drawing the GISWAK or GISWAB data-model is being created automatically. All AutoCAD layers (colors, symbols and line types included), themes and attributes are defined automatically.
Existing drawings can be selected in several ways. Besides the standard
AutoCAD and ArcCAD routines, a function is implemented that makes it possible
to select a situation drawing from an overall survey drawing.
To work with the specific GISWAK and GISWAB data the user has to select the object class in which this information is stored by using dialog boxes. Afterwards the user can choose for graphical or alphanumerical data manipulation. After choosing for graphical data manipulation several AutoCAD commands are redefined so that the geographic model can be updated automatically. There is no necessity of ArcCAD knowledge for making a geographical model of the water system by using GISWAK or GISWAB. When all graphical data for an object class has been drawn the user has to select the update button in the menu. After that the geographical model (ArcCAD theme) is updated and the dialog appears in which the user can choose another object class and type of data manipulation. When graphical data is present for an object class, the alphanumerical data can be modified. Therefore the ArcCAD functionality is extended with several functions such as selection methods, visualization of specific attributes, given domains and automation of relating databases.
All the data from the input-part of GISWAK and GISWAB can be visualized
using ArcVIEW. Because this data is registered in a structured way it was
possible to build an application in ArcVIEW version 2 using AVENUE. Therefore
a project is created in which several scripts can be reached trough menu-items,
buttons and tools. After selecting a situation drawing in an overall survey
drawing a new view is created in which all applied data is given in a predefined
way (colors, legends).
Because a lot of information is stored on the IBM AS-400 platform, a
specific module has been developed to exchange data between the AS-400
and ArcVIEW. This module is based on both dynamic data exchange (DDE) and
Rumba, an application that simulates an AS-400 host on a Windows platform.
After selecting a parcel in ArcVIEW the specific alphanumerical data in
the AS-400 is transferred to ArcVIEW.
Besides the daily operation of the water management system, maintenance
of water systems is of great importance. At present, local experience and
tradition are dominating the maintenance practice of most water-boards.
Up to now, the traditional maintenance methodology meets the needs concerning
execution of maintenance works, but does not meet the needs for planning
and budgeting the maintenance activities. At this moment a decision support
system for rational planning and calculation of maintenance of water maintenance
systems is being developed as a Ph.D. research program of the Delft University
of Technology with cooperation of STOWA and a group of water-boards. Such
a decision support system needs a lot of information that can be received
from information systems such as GISWAK and GISWAB. The completion of this
research program is scheduled for 1999.
M.P.A.M. van de Looij MSc.
Researcher
Delft University of Technology
Faculty of Civil engineering
Section Land- and Water management
PO-box 5048
2600 GA Delft, The Netherlands
Telephone: (31) 15 2781646
Fax: (31) 15 2785559
E-mail: m.vdlooij@ct.tudelft.nl