In the year of 2009, there was a Station Fire in Los Angeles County, in Los Angeles River Ranger District and Angeles National Forest. This fire started to burn on August 26 2009, and the fire is  was fully contained on October16, 2009. In this incident, 2 fireman were killed, and up to 160,577 acres of land were burned. (Station Fire) From the Station fire Perimeter Map, we can see that the area of the fire on Aug30 was almost quadruple than the area of the fire on Aug29, and double the next day. In lab 7, the fire spreading patterns are studied, and i think the major factor that leads the fire spread this fast is due to the Elevation.

As well known, fire will continnus to combus when the three elements of fire triangle exists. Accroding to wikipedia, the three fire tirangle elements are heat, fuel, and oxidizing angent(such as oxygen) (Fire Triangle). Since the cause of this incident is because of arson(2009 fire summary), the require of heat is fulfilled; secondly, there are lot of woods in the angeles national forest, and they can used as fuel for burning; lastly, there was enough oxygen since the incident is occur in an open area. So, we can assume that the fire can continue burning until one of these three element used up. In this incident, the fuel may used up first because there is no rain and not enough man power to lower the heat, and the oxygen will not used up.

With the existing of fire trangle, we can futher analysis how the fire can be spread. According to Principle of Fire behavior, Fire seldom self-propagate (spread) through surface, so non-self-propagate(such as wind and Elevation) is the major reason that why fire spread. (P.84 Quintiere)The Defintion of flame spread is that process in which the perimeter of the fire grows. There are two major types of frame spread, assist and opposed frame spread(P.85 Quintiere ). In this incident, the fire is spreading from low land to high land, and this is one kind of upward spread (assist spread)(P.90 Quintiere ) . In the map, the green coloer means low land, and the brown color means high land. We can see that the fire perimeters were extended toward the brown color much more faster (assist frame spreading) than going to the green region (opposed frame spread).The spread rate can be calculated by a equation that stated in the book.

Aonther instersting point that I found out from the theme map is: the spread of fire is not much related to the rivers and stream, is that, the rivers and stream could not stop the spreading of the fire. We can see from the map; even though there is river or stream present, the fire will continue spread to the high land direction. I think the reason why the river cannot stop the spreading of the fire is that the river and stream may lower the heat, but the heat is still enough to combus with fuel and oxygen, and to propagate.

All in all, in this station fire incident, the fire spread from lowland to highland. The elevation is one of the major factors that plays an important role in this incident.

"Station Fire".Inci Web Incident Information System http://inciweb.org/incident/1856/. Nov 28, 2010 03:33

"Fire Triangle"http://en.wikipedia.org/wiki/Fire_triangle Wikipedia. Nov 28, 2010 03:33

"2009 fire summary" http://www.fire.ca.gov/downloads/redbooks/2009/02-wildland-statistic-all-agencies/11_2009_Fire_Summary.pdf California Department of Forestry and Fire Protection. Nov 28, 2010 03:33

Quintiere G. James. "Principle of fire behavior." Delmar, a division of  Thomson learning.(1998 )

PS: This is the first time for me to use ArcGIS10, and I found out this new version is more easier to handle then the 9.3version :)

Lab6 DEMs in ArcGIS

3D image of the location

            In this lab, I selected the North-East part of Los Angeles as the map location.  The top of the map lays on 34.43638 degrees and the bottom of the mas lays on 34.2761 degrees; the left of the map lays on -118.67638 degrees, and the right of the map lays on -118.43805 degrees. This DEM is using GCS North American 1983 spatial reference, and using D North American 1983 Datum. This DEM have 858 columns and 577 Rows. Each cell is 0.000277x0.000277 in size.

Lab5:Projections In ArcGIS

  With no projection, the distance (D) between Washington, D.C. and Kabul is 6936.35 miles 

World Equal Distance Cylindrical Projection:(D)=5068.2miles
World  Equal Distance Conic Projection:(D)=7021.4miles

World Cylindrical Projection: (D)=10120.3 miles
Mollweide Equal Area Projection:(D)=7930.84miles 

WGS 1984 Web Mercator Projection: (D)=10119.7miles
Mercator Projection (D)=10119.6miles

          

            In Lab5, different projections of world map is created by using ArcGIS. Map projection is the methods and procedures that are used to transform the spherical three-dimensional earth into two-dimensional planar objects,  such as paper, and computer screen. However, there are no perfect method to project a three-dimensional object into two-dimensional without any distortion, so different map projections have different preservations. There are three main types of map projections. They are: Equal distance projection, preserving distance; Equal area projection, preserving area; and Conformal projection, preserving direction.

                Map projections are significantly important in map making, because different maps have different usages, and different preservations. Like in this lab, one of the purpose is measuring the distance between Washington, D.C. and Kabul in different map projection. The actual distance between the two cities is 6936miles. As the data above, the distance error of conformal projection and equal area projection is large. The delta D can up to about 3000miles. Also, not all equal distance projection can be used to measure the distance between  Washington, D.C. and Kabul, because there are two types of equal distance projections, longitude preserving and latitude. In this lab, the distance between Washington, D.C. and Kabul is along the latitude, so the World Equal Distance Cylindrical Projection is not doing a good measurement because it is a longitude preserving projection. But the measurement of World Equal Distance Conic projection is quite close to the actual value(actual=6936miles, measure=7021miles). From this, the significance for the map projection can be understood, and different kinds of map projections do make a different in measurements.

                In this lab, it is needed to do some research on projections of map. In ArcGIS, there are a lot of projections can be used in ArcGIS, and I found out that there are not only conformal, equal area, and equal distance projection, but also some other projection, for example, Gall's Stereographic Projection; this projection preserve in both shape(area), distance, and direction, but these preservations are only true at latitude 45N and S. In the other places other then latitude 45N and S, most of the distance, shape, and direction are generally distorted. Knowing which projection is the map used, and understanding how the projection work out is the only way to avoid the peril of using the wrong map projection.

            All in all, map projection is a fundamental topic in Geographical information system. I think there are still a lot of improvements can be done in map projection since until now, there is no perfect projection can use to represent the three-dimensional world. With the advance technology in the future, may be there are some two-dimensional object can turn into a globe and it can show the real world with no distortion.

Lab4

In this lab, the basic elements of ArcMap are introduced by ArcMap tutorial. Before going throguh the tutorial. I tried to find a legal download version, which is the ArcGIS 10 trial version(This version is free for two months), but since the ArcGIS10 requires 64-bit CPU and 64-bit operation system, and my computer has not been upgraded yet, so I used ArcGIS9.3 for this lab. The tutorial starts from exploring the data with the tools in the tool bar, then the tutorial teach us how to edit geographic features,to work with tables, and to work with map elements. Since I have some computer science background, and I follow the instruction in the lab, for example: save in a relative path file name, how to export the map as .jpg format and so on, I can get though the tuturial fluently and make the map.

After using the ArcGIS, I find out that this software is very powerful. In each frame, there are lots of layers, and features, and these layers and features are store as a single file; each of the layer or feature can represent different spatial data or attributes, and ArcMap can marge them together. Moreover, AcrMap can do a lot of editing about these frames and layers such as, copying and pasting one layer in a frame to another frame, changing the color of the layer and features, doing calculations of the attributes in the table, plotting graph, doing geostatistics analysis, and so on. Also, this software is kind of user-friendly, it provide a lot of explainlations in every windows, and the tutorial is clear and detailed. Futhermore, the ArcGIS has a great diversity. I looked up the ESRI offical website. For ArcGIS10, there are more then 1GB of tuturial; this means the tutorial PDF file(3.6MB) that we go through, contains a very little portion of function of the whole software. What we did is based on some exsisting maps and edit them. From these, we can see ArcGIS is extremely powerful.

The pitfalls and potiential become more obvious after experiencing the workout of GIS software.The first problem arise is the software. In this lab, if the school is not going to provide us the software, we need to buy the software ourselves and the software is not cheap; and this is the first barrier which stops new learner to learn how to use GIS. Also, a lot of softwares have high hardware or software requirement, like the problem that I encounter using ArcGIS 10. This may implies a basic computer knowledge is required for using GIS too. Besides the software issue, learning how to use GIS is time consuming. In this lab, we just edit the templates, but not create our own work, and this still use a lot of time. The time reuqired to train a professional GIS software user is long, so a lot of people would rather using Neogeography rather than using GIS. Also, the format of out put of GIS software is mainly paper, and GIS contain a huge amount of metadata that paper is not enough for displaying all the information which store in the database. Like in this lab, we are difficult to display all the data sets in one page.

On the other hand, GIS also have a lot of potential. First of all, it is professional. When I edit the map using ArcMap, the software will mentain the accuracy. For exmaple when we import a layer into a frame, the features in the layer will fall in exactly the position and size that correspond with the real world. Secondly, everything in the map is changable. Unlike Neogeography, user can only edit some of the elements in the map; user can edit the entire map, so GIS is a better platform for user to create their own map. Thirdly, GIS can do complex calculation of attributes, and express these attributes in several ways. This is all I discover in my first ArcMap experience. I believe as I go over the course, I will discover more and more potential and adventages of GIS.