GIS Applications for Dumping Site Selection

The aim of this paper is to highlight a user interface developed under ArcView 3.0a using a combination of avenue and dialogs to help in the process of dumping site selection. The most important conclusion is that non-GIS users can select interactively their site within 10-15 minutes. However, if the user is not satisfy with the output zones he/she can iterates again and again.

1.0 Introduction

1.1 Dumping site selection

Among the factors that governing the selection of the dumping site are:

• Institutional factors such as restrictions by local authorities for dumping due to other priorities.
  
• Economical factors such as dumping site should be at minimum distance from roads so that collection vehicles can travel through the optimum route.
  
• Environmental factors such as noise contamination due to trucks movement; soil, surface water, and groundwater contamination due to leachate; and atmospheric contamination due to emission of carbon dioxide (CO2)and methane(CH4).

The criteria for selecting a dumping site is almost similar all over the world with some constraints related to locality. However, some of the criteria factors may conflict with each other; therefore, some compromises or tradeoffs between criteria will be necessary if the process is to materialized (Michael, 1991).

1.2 The role of GIS in solid waste management

Many companies work in the filed of solid waste management in Malaysia have allocated budget for GIS. For example, Alam Flora Sdn. Bhd. (AFSB) is a company responsible for the collection, transportation, and disposal of 70% of Malaysia's solid waste. It has taken an initiative to setup a GIS like ArcInfo and ArcView as key components for managing its information (Keir, 1997).

1.3 User interface

The increasing level of complexity of GIS systems requires special consideration to the user-friendliness of the system. This may be discussed from two points of view: from the viewpoint of specialized users, calling for sophisticated capabilities; and from the viewpoint of wide audiences, requiring the ease of use for non-GIS users. Raper and Rhind (1990) argue that ease of use is a vital criterion for the selection of an appropriate GIS. It is generally accepted that a system, which is easy to use, can help cut recruitment and training costs and help retain staff.

1.4 The objective of this paper

2.0 User requirements/ the call for GIS

The people of Pulau Langkawi have complained about the scarcity of dumping site facilities and asked the government to locate a new dumping site. The site must meet the requirements of the Environmental Quality Act (EQA) 1974 issued by the Department of Environment(DOE)Malaysia. For more detail about DOE the reader can refer to the web site: http//www. jas.sains.my/doe/.

A study carried by Lee (1997) for the production of zoning plans for Pulau Penang (Malaysia) has showed that to produce one set of zoning plans requires 3 or 4 technicians working for a period of 3 to 4 weeks. Using GIS modeling the zoning plan can be produced in an hour or less. A same time 3-4 weeks utilizing 3 to 4 technicians is expected for locating a dumping site manually in Pulau Langkawi, because the two islands have almost similar area.

In order to reduce the time and labor for locating a dumping site in Langkawi, the local authority has identified GIS as a potential and valuable tool that can be used in the siting process. It is then decided to develop a user interface that provides a GIS analysis to identify a list of suitable dumping sites for further investigations. Furthermore, it is realized that the data obtained for the siting process can be used in for other purposes using the same GIS principles.

2.1 ArcView as a system for development environment

In this study the user interface is built using ArcView GIS 3.0a mainly due to the following reasons:

• Low cost desktop GIS.
• Customization is based on Object Oriented (OO) language using Avenue.
• Supports Inter-Application Communication (IAC) with other applications through Dynamic Data Exchange(DDE, Dynamic Link Library(DLL), and Remote Procedure Control(RPC).
• Supports Client/Server DBMS access anywhere on a network (dBase, SQL).
• Supports integration of different data sets such as CAD, Shape files, ArcInfo coverages, multimedia image, and link real-time events such as GPS.
• Supports internet applications using ArcView Internet Map Server and MapObjects.
• Its extensions such as Spatial Analyst, Network Analyst, and 3D module is vital for future monitoring of the dumping site.
  

For more detail the reader can refer to Esri web sit at: http//www.Esri.com

ArcView as a low cost desktop GIS system has gained wide use and for this reason numerous efforts to improve its spatial analysis is done by many organizations other than Esri. For example, SWEGIS. It has developed an extension that can help in spatial analysis under ArcView (Buffer, Clip, Dissolve, Distance, Eliminate, Erase, Intersect, Union, etc.). For more detail about this extension the reader can contact: mikael@swegis.com

2.2 System description and functions

The system consists of a series of buttons (Figure 1). Once the user clicks on a button the system prompts the user to select a suitable value for modeling. For example if the user clicks on "Groundwater" button, then the system will:

• Activate the original theme from which the selection will be made e.g. groundwater theme, get its attribute, selects the field where the groundwater productivity is stored, removing duplicates values in the field(get unique) and sort them.
• The sorted output list is displayed in a list box for the user to select from it. If there is a selection the selected records (Bitmap) will be saved in the memory and converted to a theme in a separate view giving it a name e.g. "Suitable groundwater".
• The system will check if there is an existing theme with the same name as above e.g. from previous modeling process, if it exists it will give the user an option to delete it or enter a new name for the theme.

Other buttons such as Districts, Landuse, Rainfall, Roads, and Soil (Figure 1) have the same functions as "Groundwater" button described above.

Paying attention to the principles of user interface, consistency is maintained between the sequences and prompts for all buttons. These sequence are:

• Select a factor to be used in modeling e.g. landuse.
• Activate the theme and select a suitable value from its attribute according to the user's criteria.
• Confirm the selection.
• Create a new theme based on the selection and give it a name "Suitable" + the parameter used for modeling e.g. Suitable Landuse.
• Clear the global variables and the selection (bitmap) from the memory using (av.ClearGlobals,av.PurgeObjects) commands.

Figure 1: A user clicks on Groundwater button, the groundwater theme is activated and its attributes are displayed for the user to select.

The button "Final Zones" (Figure 1) allow the user to view the final zones satisfying all the model parameters (criteria) and a report about the zones (Figure 2).

The program for the "Final Zones" button checks if the modeling process is initiated and checks how many parameters are used for modeling. If there is only one parameter, it will be displayed as a suitable zone, if there are two, the common area will be taken as a suitable zone. More than two parameters will be treated in such away that each two parameters will be intersected together. The central function of this option is analogous to INTERSECT in ArcInfo. If there is no common area between any two selected parameters the system gives notification about that. In general the system provides error, information, and warning messages for the user whenever it is necessary.

For example, if a user would like to locate a new facility satisfying the following criteria.
1. To be in district Kuah.
2. To be in areas with soil type clay.
3. To be in areas with low groundwater productivity.
4. To be within 500m from the main roads.

To find zones that satisfying the above criteria the user first clicks on the button "District" and from the available districts he must select Kuah. Upon the selection, the system will abstract areas that fall in district Kuah only, save them as a separate theme and display them. Similar sequences will be done for soil type and groundwater once the user clicks on "Soil" and "Groundwater" buttons. Clicking on "Road" button the system will prompt the user to enter the suitable buffer distance in this case 500m.

To find the final zones satisfying the above criteria the user can click on the "Final zones" button. The system will find the common areas between the abstracted themes and finally displays the suitable zones and a report about them (Figure 2).

Figure 2: A map showing final suitable zones associated with a report.

2.3 Problems associated with the system development

• Due to the memory limitation (32 MB RAM) of our PC and ArcView memory capability, the system in many cases aborted especially when a theme has many features (records) selected and they are saved as Bitmap in the memory.

• The modeling process usually requires many iterations (simulation) with different scenarios. If the iteration is done many times the number of themes generated may take hundreds of Mega Bytes (MBs) of storage. Putting space in mind a question arises:
  Is it possible to delete a theme and its associated files (file1.shp, file1.shx, file1.dbf) from a view and a hard disk (HD) while the project is active?
  It was found that it is possible to delete a theme from a view using the command "theView.DeleteTheme(name of theme)" and remove its associated attributes using the command "av.GetProject.RemoveDoc(adoc)". While deleting a theme from the hard disk, the access to the theme is denied because the theme is currently under an active project. In order to overcome this problem the same theme name is given from each simulation process and the system prompt the user whether to overwrite the existing theme or enter a new theme name.

• Dialog designer will be a good alternative for Visual Basic if its capabilities such as color, font, images, and icons are improved. It was found that it is easy to address ArcView directly from the Dialog designer rather than passing a command via DDE in Visual Basic.

Conclusion

References

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