Overview
You have been hired as a GIS consultant to address one of the two real world issues facing the Royal National Park:
1) Mapping susceptibility to landslides, or
2) Identifying suitable locations for a whale watching lookout.
To earn your pay for the job (i.e., your marks for the major assignment), you need to produce a final report detailing the steps you took to solve the problem, your findings, and a discussion of the implications of those findings. You should include visuals (maps, charts, tables) where necessary to illustrate your results.
The final report is due via SMAH Central by Friday in Week 12. Word limit: 3000
The Projects
Imagine that you have been hired by the NSW Office of Environment and Heritage (OEH) as a GIS consultant. Your study area is the Royal National Park (RNP), located on the NSW coast between Wollongong and Sydney. OEH has identified the two issues of concern noted above.
You must choose ONE of these issues, and design a GIS analysis to address it. You are provided with GIS data layers and decision rules, but you must determine what ArcGIS tools are needed to complete each project based on what you¡¦ve learned throughout the semester. A good way to start determining what tools are needed is to draw a cartographic model diagram BEFORE you start your analysis in Model Builder. Once you have developed a plan for the analysis, you need to do the analysis, recording every step in Model Builder and produce results
Note that there are two parts to each project: required and optional. You must complete the required part to PASS the assignment. If you have time and are interested in earning a higher mark for the assignment, you can also attempt the optional part(s).
Below are descriptions of each of the two projects from which you can choose:
Option 1: Landslide Susceptibility
Landslides occur when a mass of rock, debris or earth moves down a slope, and are typically triggered by an external event such as such as intense rainfall, earthquake shaking, water level change, storm waves or rapid stream erosion (Dai et al 2002). The risk of a landslide occurring, therefore, depends both on factors that predispose a slope to failure (susceptibility) and on the likelihood of occurrence of trigger events. To assess the extent to which a landslide may damage the natural environment, human infrastructure and potentially cause loss of life, it is also necessary to estimate how large the slide will be and where and how far it will travel down slope (Dai et al 2002). Detailed quantitative assessment of landscape risk (susceptibility + likelihood of trigger events) thus requires considerable data and field work as well as complex statistical modeling, which is beyond the scope of this project.
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However, it is possible to simplify the analysis to gain a general idea of the susceptibility of the RNP to the occurrence of landslides using freely available data in GIS. If warranted, this could then be followed by more detailed studies in future to further delineate susceptibility and risk across the RNP. For example, key factors that tend to be present when landslides occur include:
a) Slope greater than 10 percent,
b) Geologically recent (last 10,000 years) previous landslide activity,
c) Stream or wave activity undercutting or cutting into a bank, reducing the stability of the surrounding land,
d) The presence or potential for snow avalanches,
e) The presence of an alluvial fan (indicating vulnerability to the flow of debris or sediments),
f) The presence of impermeable solids (i.e., silt or clay) which are mixed with granular soils (i.e. sand and gravel).
Of these, (a) and (c) can be readily mapped for the RNP with available data in ArcGIS and as such can form the basis for a preliminary estimate of landslide susceptibility across the RNP.
Required:
1.1 Map the areas of the Park that are susceptible, moderately susceptible and highly susceptible to landslides (see landslide susceptibility decision rules below). Calculate the % area of the Park in each zone. Is there any spatial pattern to where the susceptible areas are located?
1.2 Identify the sections of sealed roads within the Park that fall within each susceptibility zone. What implications do you think this will have for evacuating visitors to the Park after a landslide if necessary?
Optional:
1.3 Flooding can trigger a landslide in a susceptible area. Find the percentage of all susceptible areas (susceptible, moderately susceptible and highly susceptible combined) that are also located near a water source.
1.4 Landslides can have long term impacts on vegetation. Find the average susceptibility level (defined as: not susceptible = 0, susceptible = 1, moderately susceptible = 2, highly susceptible = 3) for each vegetation type. Which, if any, vegetation types are on average moderately or highly susceptible?
1.5 Bonus question: use the scientific literature about landslides to determine the likely factors needed to estimate the trajectory of a landslide starting at a given point. Based on this, what data layers would you need, and what tools would you use in ArcGIS to combine them and how would you do it?
Decision Rules for landslide susceptibility:
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1. Susceptibility to a landslide occurring is defined as:
„X Highly susceptible = the presence of cliffs at risk from undercutting by water erosion (see #2 and #3 below).
„X Moderately susceptible = if grid cell is steep enough to be considered a cliff (see #2 below), but not at risk from undercutting by water erosion (see #3 below).
„X Susceptible = slope greater than 10 percent but not steep enough to be considered a cliff.
2. A grid cell is assumed to be a cliff if: slope is greater than 35 degrees).
3. A cliff that is deemed to be at risk from undercutting by water erosion is located within 50 m of a water source.
4. For question #1.3, ¡¥near a water source¡¦ is defined as within 80 m.
Option 2: Suitable locations for a whale watching lookout
The Royal National Park is a popular destination for all sorts of recreational activities, including whale watching. Whales migrate every year moving along the entire NSW coast as they move between their hunting grounds in Antarctica and their breeding grounds in tropical Queensland. Their migration routes are within short distance of the coastline, making the Royal National Park a desirable location from which to observe them given the frequent vantage points from which the sea is visible within the Park. Your task for this project is to help Office of Environment and Heritage identify areas in the Park that would be suitable for the creation of whale watching platform.
Required:
2.1 Map the point locations in the park from where at least some view of the ocean is possible. Calculate the % of the points across the study area that these represent. Is there any spatial pattern to where these are located?
2.2 Map land areas that are unsuitable, somewhat suitable, suitable, and highly suitable for the installation of a whale watching platform (see Decision Rules below). Find the points identified in #2.1 that are located within the highly suitable areas and identify the top three based on the area of ocean that is visible from each site.
Optional:
2.3 Perhaps people would be willing to walk or bike along an unpaved trail to reach a whale watching platform. Accordingly, change Decision Rule #3 such that sites are suitable if they are located within 400 metres of any road, track or trail (rather than just paved roads and the highway) and recalculate your
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answers for #2.2. How much of a difference, if any, does this make to how many highly suitable sites exist for the whale watching platform? Does it change which sites are ranked as the top three?
2.4 Map the areas that are visible from the highest ranked site (from #2.2). Explain why you think the top ranked site can ¡¥see¡¦ the largest area of ocean. Also explain why you needed to use ¡¥demlandsea¡¦ instead of ¡¥dem¡¦ to do the analysis.
2.5 Bonus question: Assume that all forest types have a typical height of 10 metres and recalculate the visible areas from the highest ranked site (from #2.2). By how much area does the visible area shrink or grow compared to what you found for #2.4? Explain why you think this is the case. How might this change if you assigned a more realistic height to each vegetation type found across the RNP?
Decision Rules for siting the whale watching platform:
1. Point locations which offer some visibility over the ocean must contain at least one ocean grid cell that is visible.
2. Areas which are at least somewhat suitable for the installation of a whale watching platform must not be located within water bodies or vegetation types that are predominantly wet (such as swamps, lagoons, saltmarsh, mangroves, wet riparian scrub, or water).
3. Areas that are suitable, must meet the criteria in #2 above, but also are located within 400 metres of paved roads. Note that the highway is a paved road, but the railway and walking trails are not.
4. Areas that are highly suitable, must meet the criteria in #2 and #3 above, but must also be located in areas clear of tall vegetation so the view is not blocked (no types of forest or woodland).
