LAB 7

ArcGIS & A SECONDARY SOURCE

The 2000 US Census

        The maps created below depict the percentage of Asians, Blacks or some other race in every county in the continental United States. They are the results of the 2000 Census which asked respondents to choose one or multiple races to describe themselves. This Census tried to place better focus on understanding  the diversity across the country. The majority of the people, 98%, chose only one race to describe themselves (Cassidy & Grieco 2011). The maps are visual interpretations of the results and shows the physical/spatial distribution of some of these races. I chose this specific yellow to brown color gradation because it shows great contrast between high and low concentrations of people. 

         About 10.2 million people, or 3.6 of the total population, chose their race as Asian (Cassidy & Grieco 2011). A large percentage of Asians live on the West Coast of the United States especially in central and southern California and the north-west of Washington. Throughout the rest of the continental United States, there are scattered counties with high percentages of the Asian race. The high concentrations in the west may be explained by immigration history. In the early decades of the 19th century, many Asian immigrants were processed through Angel Island in San Francisco, California and stayed within the state. Because the counties in the west are so large, if taking the number of counties in consideration, one could say that Asians do not have large percentages in too many counties. It is also important to note that the highest percentage a county has of Asian race is 46%, which is a great contrast to the highest percentage of Blacks. 

            The map above shows the there are many counties in the United States that have at least 25% of Blacks. Approximately 34.7 million people, or about 12%, reported only their race as only Black (Cassidy & Grieco 2011). Of all the three maps, this one shows the most grouped concentrations of one race. There are very few blacks in the western plains of the country.  It is clear that the majority of African Americans reside in the south or south east coast of the United States. There is a gradual decrease outward from the counties with the highest percentage of Blacks. A very plausible explanation of this distribution of people can be traced back to slavery in American history. In its early history, the slaves in the country worked in the deep south, working for huge plantations. Through marginalization and other setbacks even after the end of slavery, many Blacks did not have a good chance to leave the south. 

          This last map shows the percentages of people that reported being of some other race. Of the total population that reported, about 5% (15.4 million) chose this category (Cassidy & Grieco 2011). The highest percentage is about 39 and it is in the counties that are in southern mid-west and the western coast. As you move to the northward and eastward, the percentages drop significantly. This category of race consists predominantly (97%) of people of Hispanic origin (Cassidy & Grieco 2011). This may explain the distribution because the counties with high percentages of some other race border in close proximity to Mexico. 
        These choropleth maps can give us a greater understanding of the distribution of diversity in the United States. And even though these were the results from a Census taken eleven years ago, they give us clues about the people of the time. Those percentages and densities not only tell us about the physical distribution of people, but it can also be associated back to the cultural and social history of the nation. 




Reference:
Adapted from U.S. Census Bureau, Overview of Race and Hispanic Origin, by Elizabeth M. Grieco and Rachel C. Cassidy, Census 2000 Brief Series. Wednesday, 26-Jan-2011 
http://www.nationalatlas.gov/articles/people/a_race.html 

LAB 6

DIGITAL ELEVATION MODELS IN ArcGIS
Yosemite National Park

   
        The area I selected for my digital elevation model was Yosemite National Park, which is the largest habitat block set aside in the Sierra Nevada. I chose it because I have been making plans to visit it in the summer and so I wanted to create something that was of real interest to me. It covers 761,268 acres and over 3.7 million people visit every year. It has an elevation range of 500 to 4000 meters and so allows for various vegetation zones which houses great biological diversity. Its an inspiring place filled with waterfalls, deep valleys and mountains, which are showcased in the digital elevation models that I have created. Above is a ground level view from one of Yosemite's many valleys.

Extent Information 
   In decimal degrees:

• North 38.0188888882
• East 119.406111111
• West -119.825555555
• South -37.6013888882    

Spatial Reference

• GCS North America 1983
• Datum: D North American 1983
• Angular Unit: Degree (0.017453292519943295)

Digital Elevation Models

Three-Dimensional Rendering

LAB 5

MAP PROJECTIONS 

Significance, Perils, & Potentials 

of Map Projections 

       Map projections are important because they are a way to translate the three dimensional world onto a two dimensional surface. However, because it is impossible to retain all the three dimensional aspects, it is important to know which projection is best for the information you are trying to convey. All maps have some distortion, but different projections maintain specific aspects of the three dimensional world. These three projections include conformal, equal-area, and equidistant.

        Conformal maps preserve angles. So if two curves intersect at a specific angle, the images of the two curves on the map also intersect at the same angle. The Mercator map projection was  the standard map for nautical purpose because of its ability to represent lines of constant course as straight segments. This map preserves angles and small shapes because the linear scale remains constant. It does come with obvious distortions of the size and shape of large objects as the scale increases from the equator to the poles (note that Greenland is larger than the US). The stereographic projection also preserves angles, but neither area or distance. Like the Mercator map it creates more distortions towards the poles, but does not look as extreme (compare Antarctica and Greenland between both).

        A second type of map projection is one that maintains equal area such as the Bonne and cylindrical equal-area projections. The Bonne projection is pseudoconical with all parallels being concentric arcs of circle, all equally spaced and all standard lines. Scale is correct along the straight vertical central meridian. However, deformaties increase towards the edges of the map. The cylindrical equal-area projection is quite a contrast with the Bonne projection, but it does conserve area. It has straight parallels and meridians. The projection stretches the continents east to west and distortions also increase towards the poles.

       The third category of map projections is equidistant maps that preserve distance from one standard point or line. With the equidistant conic projection the scale is the same along all meridians because it has constant parallel spacing. It is not equal area or conformal and obviously distorts the south pole. With sinusoidal map projections, distances along parallels are preserved. It shows relative sizes fairly accurately but distorts shapes and directions. There is no distortion along the central meridian or equator.

        I have given examples of the different categories of map projections as well as specific examples for each category. Even though two maps may try to preserve the same thing, there are still discrepancies in distances as noted by the variable measurements from Washington DC to Kabul. Also, I have only provide two examples of each type of projection but in reality there are a plethora that can be found that falls under the three categories and there are even some that do not fall under any, such as the popular Robinson map projection. Note that although some projections may preserve more than one thing, it is impossible to preserve all. Nevertheless, it is important to understand the different projections and what they conserve to appropriately convey a certain set of information. These projections have been used for many years and will continually be used for many more to come because they are so integral in understanding distances, angles, and areas of places around the world. 

Examples

LAB 4

ARCGIS TUTORIAL

Proposed Airport Expansion

       The ArcGIS tutorial was great because I really got to see how different layers can be compiled together to form a very informative visual. Through the map/model that the tutorial made me create I got to really see its use. This map in particular allows someone looking at it to see the impact a proposed airport expansion would have on the community. I really enjoyed creating it. 

 Pitfalls and Potential of ArcGIS

        ArcGIS was designed by ESRI as a geographic information system modeling and mapping program. Through the tutorial that was provided I became a little more familiar with what accompanies the task of using ArcMap as well as ArcCatalog. The program allows creativity, as made possible by the many different commands that can be utilized to create more than I  had imagined. Different editing techniques allow for a multitude of possible combinations of attributes that allow for many different map creation. Graphs can also be integrated as a supplement to maps.

       Though the tutorial provided step by step guidance as well as visual aid, I still found it to be tedious and very detail orientated. With ArcGIS, patience is a must because it can be very time consuming, but after awhile I started seeing consistencies of where certain commands were located. I can tell that getting a good grasp of the program is going to take a lot of time and practice. Making sure the progress was saved properly was also a difficult task that frustrated  me and many of my peers. Of course if all the students were able to work through their own computers then it would not be a problem. This is not possible because the program is really expensive. However, it is obvious that if someone was serious in pursuing digital modeling and mapping, this is a great program. 

       GIS has great potential in spatial analysis because so many different layers can be included in a creation. There are many ways to  represent the data and features. Mapping has come a long way with the advent of this program and it has given and will continue to give great contributions to the study of geography all around the world. It is also great because a seasoned professional can map and and compile data as long as he is provided the proper attributions without surveying an area himself. 

      The ability to properly utilize ArcGIS needs experience and a lot of practice. This means that its more suitable for professionals. Although maps can be professionally made, it does not necessarily mean it is 100% accurate. Human error is common and although the map/model creator may be accurate and precise, the data and attributes he uses for the projection may not be accurate.  It is important to still be wary of this fact. Overall, ArcGIS has much more potential and positive contributions than its pitfalls. As it becomes  utilized and updated more and more, I am sure that it can only get better. I personally cannot wait to become proficient in employing this program.