Week 5 Work – Savannah Domenech
I hog up much less room this way. Click the text above to view my Week 5 work.
Module 1: 8/23/2023 to 10/10/2023, OWU Environment & Sustainability
I hog up much less room this way. Click the text above to view my Week 5 work.
Chapter 1:
Chapter 2:
Exercise 2A
Exercise 2B
Exercise 2C
Chapter 3
Exercise 3A
Exercise 3B
Exercise 3C
Exercise 3 dimension
Chapter 4
Exercise 4A
Exercise 4B
Exercise 4C
Chapter 5
Exercise 5A
Exercise 5b
Exercise 5c
Chapter 1 (Law / Collins)
Exercise 1:
Chapter 2:
Chapter 3:
Questions :
Chapter 4:
Questions:
Chapter 5:
Questions
Notes:
Chapter 1:
Chapter 2:
Chapter 3:
Chapter 4:
Chapter 5:
Chapter 1
I actually enjoyed this chapter a lot because it expressed different types of analysis in numerous parts of daily life (%forest, burglaries, parcels near a liquor store, etc) I cannot stress how cool it is that GIS is around us more than just using it for maps and navigation, which was my initial thought prior starting this course.
Keeping in mind what different types of geographical features are and how they are represented, a discrete feature is a feature that has definite boundaries. An example of this is a lake or a building. Continuous phenomena is something that can be measured regardless of location, so in the book it mentions temperature or precipitation. (no gaps, starts off as sample points.) Lastly, summarized data is the density of individual features within a boundary, the data applies to a whole area, but isn’t really a specified location. (Example: 740 area code is typically in Southeastern Ohio, but it isn’t specific to what county it is in. It could be Guernsey, Belmont, Noble, or even Marion county. It’s more than those counties. I’m just using the example that it isn’t limited to one county.) There are two ways to represent GIS model wise: These are called vector and raster.
Vector: This is defined using x,y locations in an area which does not have boundaries, GIS then connects these dot-like coordinates to draw lines and outlines. These dots can be areas, lines, events and of course locations. Main takeaway: Vectors utilize lines as a way to create almost an outline for locations, streams, and areas. ->discrete and summarized data typically
Raster: These are seen as more of a matrix of cells with continuous space. Used in layers, but layers can be added on top of one another and analysis is then done by combining all of the layers to make a new layer that contains cell values. This seems to rely more on scale of the cell, because it changes the layer being analyzed and also the presentation of the map. Main takeaway: cell size should be close to the original scale of the map, because using too large or small of a cell size can cause conflict with information and lack of precision on the map. ->continuous values
Both Vector and Raster: Continuous categories.
Map projections: locations on the globe, but are translated onto a flat surface like a map (Flat earth vibes, not liking that but okay GIS.)
Coordinate system: Uses specific units to target features in a 2D space, as well as the origin of those units.
Good gravy, this chapter is packed with information
I liked that it mentioned land use in this chapter, we learned about that in GEOG 347, so that’s rad.
Chapter 2
Now there is some degree of significance to plotting and mapping things, mainly because when we look at a map, we are looking for something specific, whether it is a similar structure or a pattern that is familiar to us. (When I drive home, sometimes on Apple maps I look specifically for the Y bridge on Zanesville because it is what I use to get into Cambridge, I can see this on a map and in person.) Maps also can be used to determine trends in areas (ex: Police officers investigating crime activity and seeing whether or not it is in the same area or different parts of the city.)
Maps are dependent on audiences and what issue is being addressed. (I really liked the color palette for the keys, sorry that’s random but it’s very pretty.) Features require locations, and locations require coordinates prior to being typed into a geographical database (so latitude, longitude, and addresses.)
It’s important to use specific colors that draw attention to different categories on maps, oftentimes soil maps utilize different colors and codes because soil types are fairly wordy sometimes, but they put the full name in the legend/key. (I think back to a time when I was in a soil microbial lab where this person showed us all the soil types in Kalamazoo county. Here’s the website if anyone wishes to take a gander at it, https://websoilsurvey.nrcs.usda.gov/app/WebSoilSurvey.aspx
After the hour-long talk the person ended it by saying soil doesn’t matter and I wanted to cry. anyways.) Using recognizable features in maps are extremely important to audiences, especially those who live there that are looking for specific rivers, landmarks, maybe a weird statue. Patterns can be seen just by the human eye, but sometimes maps have “easter eggs” for those who may see different patterns, this varies on how meaningful certain details are to people.
Chapter 3
So why are we actually mapping all details? Shouldn’t we just focus on mapping the most important features out there? NOPE. Everything is significant in some sort of way, and may actually be beneficial to someone. (typically businesses.) You can include and exclude things from maps just by a degree of relevance, because honestly it may be weird to have “how many slugs are in each yard of Delaware, OH” on a map that shows who all has a subscription to oriental trading company (I bet I just unlocked a memory for you, you’re welcome.) In legends, specific things can be shown by having bigger or smaller, or thinner/thicker lines. (Expressed by having big circles as 2501-8000 employees, or very thin lines as unknown fish habitats in streams.) Mitchell describes continuous phenomena as more of a colorful part of the map. Where areas are displayed as graduated colors and surfaces are contoured, or a 3D perspective, but can also be graduated. (Remember my palette comment in chapter 2? I think this is what I meant. My heart and little GIS mind was in the right place.) Typically lighter colors are expressed as little or a lack of in a map, while darker more shaded in colors are seen as plentiful, lots of. I feel you can heavily argue the point made on page 56 of the Mitchell textbook based simply on perspective. Maps can be a way to express data or even trends especially if used in a long term fashion. (Long term deforestation, crop rotation, droughts, maybe long term crimes? Sue me.)
Counts and amounts: total numbers. (I actually don’t know what I truly meant by this, but I’m going with it.)
Summarizing by area is a bit harder, because counts and amounts throw a wrench in the patterns if areas are different in size (use ratios so this is accurately represented)
Ratios: Relationship between two quantities and are created by dividing one quantity by another.
Standard classification schemes:
Chapter 4
Mapping density is very important when it comes to looking at concentrations of features in an area.
The Dense surface is created via a raster layer and is more blobby (I think of this as when you look at a map when a storm is coming. Is it a cluster of dots coming at your town or is it a huge blob?
Be careful with dot patterns, they should be an appropriate size for the areas on the map. Too small or too large can obscure patterns which messes up the point the map was trying to make.
Units allow you to specify areal units you wish to use for density values.
Main takeaway from this chapter: A map is so much more complicated than I ever anticipated in my lifetime, there are so many factors that go into this and I didn’t even know you could incorporate standard deviation into a map. That’s insane, mapmakers are insane.
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Chapter 1: Introducing GIS Analysis
> GIS analysis is the process of finding geographic patterns in data and at the relationships between features.
Understanding Geographic Features
Discrete Features / Data: The actual location can be pinpointed
Continuous Phenomena / Data: Can be found or measured anywhere (precipitation, temperature, etc.)
Features Summarized by Area:
> Shows the density / counts of features within a boundary
Examples: Number of businesses in a zip code, total length of streams in each watershed, number of households in each country
Two Ways of Representing Geographic Features
Vector Models:
> Locations are represented as points with geographic coordinates
> Lines, such as streams, are represented by a series of coordinate pairs.
> Areas are represented by borders that are closed polygons.
Raster Models:
> Cell size affects how the map looks as well as the results of the analysis, and should be based on the original map scale and minimum mapping unit
> Continuous categories can be represented by either the vector or raster models, but continuous numeric values are represented using the raster model.
Understanding Geographic Attributes:
Attribute values include:
> Categories and ranks are non-continuous values.
> Counts, amounts, and ratios are continuous values.
Chapter 2: Mapping Where Things Are
Preparing Data
> Before you begin mapping, you need to make sure that you have geographic coordinates assigned. If the data is already in a GIS database, coordinates will already be assigned. If not, you will have to manually enter them.
> If you are mapping features by type, you must assign each feature to a category.
Making Your Map
Mapping a Single Type:
> Draw all features using the same symbol to map features as a single type. This can suggest differences in the feature that may need to be explored further.
> You can also map features in a data layer or subset based on a category value that you create. For example, instead of mapping all crimes, you could map only burglaries.
Mapping by Category:
> Using categories can help to understand how a place functions.
> Use different categories to reveal different patterns.
> If you are displaying several categories on the same map, use no more than seven categories at a time. Most people can distinguish up to seven patterns on a map, so using more can become confusing or difficult to see.
Grouping Categories:
> Using fewer categories can make it easier for a broader audience to understand your map, but there will be less detailed information shown.
> Patterns may be easier to see if you group many, similar categories together.
> You must be explicit with what is included in each category to help others understand what your map is showing.
There are multiple ways to group categories:
Option 1:
– Assign each record in the database two codes. One for its detailed category and the other for its general category.
Option 2:
– Create a table that contains one record for each detailed code, with the corresponding general code.
– Join the feature table with the new table, and use the general code to display features.
Option 3:
– When you make the map, assign the same symbol to the detailed categories that make up each general category.
Mapping Reference Features:
> You may want to add recognizable landmarks to your map to make it more meaningful, especially to those who may not be familiar with the area they are observing.
> You may also want to reference features that are specific to your analysis so that you can observe geographic relationships.
Chapter 3: Mapping the Most and Least
Counts and Amounts:
Ratios:
> Create ratios by making a new field and adding it to the layer’s data table, and dividing the two fields containing the counts or amounts.
Class Schemes:
> The most common schemes are natural breaks, quantile, equal interval, and standard deviation.
Natural breaks:
> Finds patterns inherent in the data
> Good for mapping data not evenly distributed
Quantile:
> Good for comparing areas that are similar in size, and for data that is evenly distributed
Equal interval:
> Easier to interpret since the range for each class is equal
> Good for mapping continuous data
Standard deviation:
> Good for seeing which features are above or below the average and for displaying data that has a normal distribution
Choosing a Map Type:
Graduated symbols:
Graduated colors:
Example: percentage of population aged 18-29 (darker colors with higher values)
Charts:
Contour lines:
3D perspective views:
Chapter 4: Mapping Density
> You can create a density map based on features summarized by defined area or by creating a density surface.
Defined Area:
> Use if you already have data summarized by area or if you want to compare natural / administrative areas with defined borders
Density Surface:
> Use if you want to see the concentration of point or line features
Mapping Density for Defined Areas:
> You can map density for defined areas by graphically using a dot map or by calculating a density value for each area and shading each area based on this value.
Calculating a density value for defined areas:
> Add a new field to the feature data table to hold the density value. Then, assign density values by dividing the value you’re mapping by the area of the polygon.
Calculating Density Values
Cell Size:
> To calculate cell size: convert the density units from square kilometers to cell units (meters), then divide by the number of cells per density unit. This will give you the area of each cell. Then, take the square root of the cell area.
Displaying a Density Surface:
> You can display a density surface with either graduated colors or contours
Graduated colors:
Contours:
Hello, my name is Cailee Plunkett and I am a junior Environmental Science major from Cincinnati, Ohio. I am also a transfer student, so this is actually my first semester here at Ohio Wesleyan. I am very excited for these next two years and can’t wait to become more involved on campus. I love to hike and do anything that gets me outside, I love animals, and I am a runner.
Chapter 1:
What I found interesting about this chapter was just how many different uses GIS has, and how many people in different jobs and fields use it. For example, it can be used for farming and municipal management, but GIS can also be used to map complex networks that provide power, fuel, and water to a town or city. Waste collection routes are mapped using GIS. Even Starbucks has reportedly used GIS. I also thought it was interesting how the acronym “GIS” can be split into GISystems and GIScience, and that GIScience is almost the theory that underlies GISystems.
The Application of Remote Sensing and Geographic Information System (GIS) for Monitoring Deforestation in South-West Nigeria
In this article, GIS was used to detect deforestation in Southwest Nigeria between 1978 and 1995 and detect land use and land cover change in Southwest Nigeria as well as to assess the stability of the land. The results of the study show that in 1978, forest vegetation covered 88.25% of the surveyed area, and that this had decreased to 63.13% by 1995. With forest cover change, between 1990 to 2000, Nigeria had lost an average of 409,700 hectares of forest per year.
Urban Sprawl Development Around Aligarh City: A Study Aided by Satellite Remote Sensing and GIS
In this article, GIS was used to rapidly assess the developments of sprawl in Aligarh City. The results of this study show that the urban area of this city has increased around three times since 1971, and that around 1990, there was a sharp increase in land consumption as compared to population growth. As the city does not have a sewage treatment plant, with a growing urban area, there is less area for the water to drain into soils, and there will also be more flooding in low lying areas. By studying and watching for urban sprawl in an area over time, residential development can be better monitored.
References:
Peter, Yohanna, Innocent Reuben, and Emmanuel Bulus. “The application of remote sensing and geographic information system (GIS) for monitoring deforestation in south-west Nigeria.” Journal of Environmental Issues and Agriculture in Developing Countries Vol 4.1 (2012): 6.
Farooq, S., and S. Ahmad. “Urban sprawl development around Aligarh city: a study aided by satellite remote sensing and GIS.” Journal of the Indian Society of Remote Sensing 36.1 (2008): 77-88.