7.10 Risk and Suitability Analysis Tutorial

Thu, 11/22/2007 - 14:06

Disclaimer

The objective of this tutorial is to get familiar to the GIS software. The tutorial only covers some parts that are being done In a real analysis. The results that are being displayed in the tutorial can’t be compared with the results a real analysis would generate.

Introduction

The Output map of this tutorial is a map showing the Suitable Areas for Future Urban Development shown below.

All map layers are presumed to have been digitized, projected and georeferenced before proceeding to this R&S tutorial.

1 Getting started

1.1 Open ArcMap, select a new empty map. You will now save the map file. Click on File>Save as… in the menu bar. Browse to the folder C:\ \CLUP_EXERCISE_DATA\06_Workfolder and type ‘risk_and_suitability_v1.mxd’. Click Save/OK
1.2 Click on the add data button and browse to C:\ \CLUP_EXERCISE_DATA\00_BM and select the files:
barangays_bndry
Lake
municipal_bndry
Rivers
Roads
Click OK.
Click on the add data button and browse to C:\ \CLUP_EXERCISE_DATA\03_EN and select the file:
Hazards_total
Click OK.
Click on the add data button and browse to C:\ \CLUP_EXERCISE_DATA\04_LM and select the files:
LM04_Cl (land classification)
LM07_Safdz
Click OK. (See image below.)

2 Categorizing the land classification layer

2.1 The land classification layer has to be categorized.
2.2 In the table of contents, double click on the LM04_Cl > Symbology >Categories.
2.3 Choose “Unique values”
2.4 In the “Value Field” chose “CL_TP
2.5 Press the “Add all values” button
2.6 Press the Apply button
2.7 Press the Ok button

3 Making the Alienable and Disposable layer

We are interested in the areas that are alienable and disposable. Making the layer that contains this information. The following steps have to be conducted.

3.1 Open the selection menu >selection by attribute
3.2 The layer that we are making our selection from is the landclass layer. In the operator window type "CL_TP" = 'Alienable & Disposable'

3.3 Press the Apply button
3.4 In the layer menu right click on the LM04_Cl, then> Selection >Create Layer From Selected Features

3.5Rename the newly created layer alienable and disposable

4 Saving the alienable and disposable layer that you have created as a layer file

4.1 In the layer menu, right click on the layer alienable and disposable>Save As Layer File
4.2 Name the layer alienableanddisposable.lyr
4.3 Press the Save button

5 The Slope layer

In this tutorial we have access to the land classification layer. Assessments’ regarding the slope has already been considered within the classification procedure for the alienable and disposable land. Therefore we don’t have to add the slope layer to the analysis. However if you don’t have access to the land classification layer, the slope layer is a crucial part of the risk and suitability analysis.

6 The Air- and Water pollution layer

We have not included the air- and water pollution layer in this tutorial. However it’s not recommended to neglect these hazards when you are doing a risk and suitability analysis in real life. See chapter4.08.07 for more information.

7 Ancestral domain

We have not included the ancestral domain areas in this tutorial. However this is also a factor you have to consider when you are doing a risk and suitability analysis in real life. For further information regarding Ancestral domain, see chapter 4.09.05

8 SAFDZ layer

8.1 Open up the SAFDZ layer. The layer contains Agro-Forestry Zone, Agusan River, Built-up areas, Crop Development zone, Fishery development zone, Remaining NPAAAD and Watershed/Forestry zone.

The only one that is fully protected and therefore not suitable for future development is the “Remaining NPAAAD”. The next step is to create a layer that only contains the “Remaining NPAAAD”.

8.2 Open the selection menu >selection by attribute
8.3 The layer that we are making our selection from is the landclass layer. In the operator window type "SAFDZ_TP" = '8 - Remaining NPAAAD'

8.4 Press the Apply button
8.5 In the layer menu right click on the SAFDZ layer, then > Selection >Create Layer From Selected Features
8.6 Rename the newly created layer Remaining NPAAAD

9 Unite all the layers that are unsuitable for future development

The next step is to union all the layers that are unsuitable for future development in to one layer. The reason why we do this is that the final step will be to union this layer with the A&D layer and then delete those areas of the A&D layer that are unsuitable.

9.1 Open up the ArcToolbox window , then Analysis tools >Overlay >Union.
9.2 Double click on Union and a window like the one below should pop up.
9.3 In output features select the layers “hazards_total” and “remaining NPAAAD”.
9.4 In the field Output Feature Class, name the output file unsuitable areas_total

10 Adding an extra field in the newly created table

The reason for this is to make it easier later on when you union the layer that contains all the unsuitable areas with the A&D layer and then filter out those A&D areas that are affected by unsuitable areas.

10.1 In the layer menu, right click on the layer unsuitable areas__total, then >Open attribute table
10.2 Click on options > Add Field

10.3 Name the field Unsuit. Type=Text and Length=3

10.4 Right click on the header of the Unsuit column, then >Calculate Values.

A window pops up informing that you are about to do a calculate outside of an edit session and asks if you wish to continue. Press yes to continue.

10.5 In the operator window, type the word “yes

10.6Press the Ok button

11 Unite the alienable and disposable layer with the layer that contains all the unsuitable areas

The next step is to create a layer that contains the A&D areas that is not affected by the unsuitable areas.

11.1 Open up the ArcToolbox window , then Analysis tools >Overlay >Union.
11.2 Double click on Union and a window like the one below should pop up.
11.3 In output features select the layers ”unsuitable areas__total” and “Alienable & disposable
11.4 In the field Output Feature Class, name the output file unsuitable areas__and_AandD

12 Select those areas that is alienable and disposable and that is not affected by areas that are not suitable for future urban development

When you have made a layer that both contains the unsuitable areas and the A&D areas. You want to select those areas that are A&D and not unsuitable. To do this the following query has to be made:

12.1 Open the selection menu >selection by attribute
12.2 The layer that we are making our selection from is unsuitable areas__and_AandD. In the operator window type "CL_TP" = 'Alienable & Disposable' AND “unsuit” <> ‘yes’.

12.3 Press the Apply button
12.4 As you can see the query is dependent of two criteria’s. The first is that it is Alienable & Disposable. And the second is that the area is not unsuitable. The <> means not. So in plain text the query above says that the selected areas will be A&D and not unsuitable.

13 Create a new layer for the selected features

13.1 In the layer menu right click on the unsuitable areas_and_AandD layer, then> Selection >Create Layer From Selected Features.
13.2 Rename the newly created layer Suitable areas for future urban development
13.3 Now you have made a layer that only contains A&D areas that is not affected by unsuitable areas. When you put this layer on top of the base map layer, your map should look like the one below.

Ver 1.0


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