Final Project - New Orleans Flood Hazard Map

With the disastrous flooding that occurred in New Orleans during Hurricane Katrina, and now with the incredible destruction witnessed in northern Japan with the Sendai tsunami, the world is now, more than ever, aware of the destructive power of water. The city of New Orleans is famous for its mixture of old European flare and American culture, but asides from its cultural appeal, New Orleans is famous for being below sea level, prone to seasonal flooding from the Mississippi and heavy storm surges from Hurricanes in the Gulf of Mexico. With all of these potential threats to the city of New Orleans, both the city’s government and citizens have grown aware of the threat flooding imposes on the city. Thus, the map I created sets out to find the locations where people and businesses are most under threat of flood and flood damage.

The first step in determining how to construct and create a flood hazard map is to determine the different environmental factors that either deter or attract flooding to certain areas. Like the fire hazard map we made in class, the flood map is a sum of all flood causing factors. Once all these factors are given values, a flood map detailing all potential hazard zones is created. But before this flood hazard map is created, a list of flood hazards has to be constructed. And before these flood hazards are determined, it is also important to find good and reliable data sources to use in constructing this map, as well as a heavy amount of data manipulation that needs to occur before the data can be useful in creating a flood hazard map.

The data source used to make the flood hazard map is that of the GIS database at the Louisiana State University, Baton Rouge. The LA ATLAS (Louisiana State GIS database) acts as the central GIS database of the state of Louisiana, and is the most reliable and reputable source of shape files and raster data for the state of Louisiana, as well as for the greater New Orleans metropolitan area.

After determining the location of a reliable source of data, the search for quality and useful data, information important and relevant to creating a flood hazard map of the New Orleans metropolitan area begins. The data I downloaded included shape files on the location of levees, bodies of water, land use, elevation, soil type, and toxic waste dumps.

The first download was a levees shape file, provided by the LA Atlas, made by the USACE or United States Army Corps of Engineers, the federal branch of government in charge of constructing and maintaining the levee system. This is a polyline dataset, as levees are linear in nature. But like many of the other datasets, the coverage of the levee system is statewide, and using the clip tool, the data was clipped to cover only the New Orleans metropolitan area.

The second dataset downloaded was that of hazardous waste sites in the State of Louisiana. Collected by the EPA and mandated by law to be open to the public, locations of all sites where hazardous materials can enter the environment is provided in a shape file. Though toxic waste sites don’t cause floods, flood waters can damage these sites, potentially leaking out dangerous chemicals into the environment creating a more hazardous environment in the surrounding area.

The third file downloaded contained the locations of bodies of water in the State of Louisiana. This polygon map provides a map of every known lake, river, or marsh area in Louisiana, and like the levee map, needed to be clipped to provide coverage of the New Orleans metropolitan area. Along with the hazardous waste sites and levees, buffers were made along the perimeters. For the water features polygon, 1 mile wide buffers were made, indicating the areas flood waters could reach in the event that the Mississippi River or Lake Pontchartrain swells its boundaries due to heavy rains or storm surges. The levees were given thin 100 yard buffers because the buffer around water features already exposes the potential damage from flooding near levees, since levees run around water features. Instead, the purpose of the levee buffers is the potential of levee failure. Though flooding may inundate a home or building with water, many times, the structure of the building remains intact. With levee failure, a torrent of water rushes through the small gap in the levee, destroying anything in its path, such as the recent tsunami did in Northern Japan. Thus anybody or anything within a close proximity to a levee is under more threat of destruction due to the sheer force and power of flood waters near broken levees. The toxic waste site was given a half mile buffer because though floodwaters are dangerous and can carry these toxins, the chance of these toxins being diluted in the flood waters are much greater as you move further away from the original toxic waste site.

After creating these buffers, it was time to download raster data. The next data set was on elevation. I downloaded a 1 arc second DEM from the USGS seamless viewer. The elevation data set is given by far the most weight in the flood hazard calculation map. The reason for such high value being given is because of the fact that New Orleans is shaped like a bowl, and if there is any breach in the levees or even a heavy rain, all of the water is not going to drain to the local lakes or rivers, but will drain to the areas of lowest elevation. Large pumping stations located throughout the city of New Orleans were built to handle the water, but these pumping stations are incapable of handling such large amounts of flood water. Thus elevation soon becomes the most important factor in determining flood hazard zones.

The next data I downloaded was data on soil types. There are four main soil types in the New Orleans metropolitan area, all with different ability in absorbing and retaining moisture. Soils that were historically located under marshes are rated with the highest value, in that many of the soils are already fully saturated with water, unable to absorb any new moisture. On the other hand, alluvial soil located on the natural levees of the Mississippi has a greater ability to absorb and retain moisture as they are newer and above sea level.

Lastly I downloaded a dataset on land use. Land such a swamps and marshes were rated very low since they are already flooded, as well as urban landscapes, since concrete and asphalt both do not absorb water and allow floodwaters to travel faster than if they were flowing across other land types such as agricultural land or forested areas.

With most of the data besides the elevation dataset, I used a valuing system from zero to three or four, because besides elevation, the data are equally as hazardous. But with the elevation data set, I subtracted from the overall sum in areas with higher elevation, because the potential of flooding in areas above sea level only occurs in only the most extreme of circumstances.

The resulting flood hazard map is a calculation of all values given to certain map features using the reclassify method in the spatial analysis toolbar. In measuring the accuracy of this map I compared the results of the flood hazard map to the flooding which enveloped New Orleans after Hurricane Katrina. As with flooding after Katrina, the areas darkest (and thus more prone to flooding) were the areas hardest hit, and where the majority of the damage and destruction occurred.

Though this map includes many elements, improvement to the map can be made. With more research into the impact on flooding different elements have, a more precise flood hazard map can be created. These different elements, such as the locations of water pumps, storm drains, age of the levee system, can all be added to the map. But what this map does do is give a general knowledge of the locations that will be hardest hit by flooding in case of any major storm, giving public officials and citizens the information necessary to react quickly and distribute supplies where necessary, if and when New Orleans is hit by the next ‘Big One’.

Lab - 8

It has seemed this season that there has been an abnormal amount of rainfall, as nearly every other weekend has had some precipitation. But according to the data provided to us by the county of Los Angeles, we are still under the seasonal average in some places. The first two maps on my map layout are the seasonal average rainfall and this current season’s rainfall. The data provided by the county of Los Angeles was recorded at several stations throughout southern California. But since each station is prone to errors, many stations were lacking data relating to this current season or the seasonal average, leading to the elimination of some of the data, leaving 61 weather recording stations that had usable data.

With 61 stations of data, the interpolation is a bit more accurate than if there were less stations, but if the county of Los Angeles fixed different errors within their recording systems, these maps could be even more accurate. The last two maps are of the difference in rainfall levels, either below or above average for this year. As you can tell, the map is split down the middle, with the eastern edge receiving more rain than average, while the west is below average.

This data was also interpolated using two different techniques. All the maps on the left were interpolated using IDW or Inverse Distance Weighted, with all maps using a power of two. These maps provided blockier but understandable data results. On the other hand the maps on the right were interpolated using the Spline method. These maps are much more beautiful and visually appealing, but it seems that some of the data is exaggerated, though this method looks much more similar to weather related maps we see on a day to day basis. I wouldn’t say one is better than the other, but it seems as if IDW is a little bit more respectful of distance, but Spline follows the terrain of Los Angeles County a little bit better.

Lab 7 - Fire Hazard Map

On the surface, this tutorial and lab seemed quite simple, but once I dove head in into the project, I experienced much difficulty and confusion. The tutorial was well written like most of the tutorials we have completed, but I think what the tutorial lacked was a clear sense of exactly what we were doing and what the different maps we were to create were going to symbolize and display. I worked through and completed the tutorial quite quickly, and had a basic understanding of what the tutorial was teaching me.

Once I began to work on the station fire map, I was confused as to which maps I need to display for the final product. I made several maps including a slope, and vegetation type, as we made in the tutorial. But then I figured the most important map was a fire hazard map combination of the slope and vegetation flammability maps. So I set forth and began to work on these maps.

The first major problem I ran into was reclassifying the slope from the DEM. I kept running into large numbers that were not useful. I made sure that I was reclassifying into percent, but it still gave me large numbers. But with the help of classmates I was able to classify them correctly as well as combine the two to make a fire hazard map.

Lab 6 - Suitablitiy Analysis

The suitability analysis lab was a very thought provoking one, in that it showed the student the very power and important role GIS has in decision making for different potentially dangerous but necessary sites, such as landfills and toxic waste dumps. Comparing the lab that we completed this week with the Kettleman city dump situation and controversy, one can see that the decisions of the city or state in determining locations for dumps can have real life effects.

In Kettleman city, the toxic waste dump is built and allowed to exist by the state, but it is controlled by the federal government. The federal government uses this dump to dispose of toxic chemical or substances such as PCB’s. This dump, although filled with dangerous chemicals, is necessary to have in the state, so that toxic waste does not get disposed of in less suitable dumps located near larger population centers. As well as the importance of having the dump, the dump provides employment opportunity to people living in Kettleman city, a town located in the California central valley, where the unemployment levels are one of the highest in the nation.

The problem and controversy surrounding the dump is the elevated birth defects in the nearby town of Kettleman city. The leading chemical elevation in the town’s people’s blood is arsenic, which is naturally occurring in California soil, and though Kettleman city is a farming community where one might expect to find elevated arsenic levels, their levels are higher than that one would find naturally causing.

Using GIS, and data similar to that in what we used for Gallitan County, we could look at the location of rivers soil types and drainage, and slope of the land, and could help determine if the land in which the toxic waste dump is located is suitable for such activities. The importance of testing and mapping these factors are important because one, they can determine if the toxic waste dump is the source of the birth defects, and two, if it is practical and safe to expand the toxic waste dump in its current location, or if it should be moved to a different location all together.

By testing soil drainage, we can see if it is easy or hard for the toxic waste to seep into the soil, and then into nearby streams or rivers, or even into the local water supply. By mapping the soil drainage, we will be able to see where the waste dump is located in relation to soil types, as well as see the location of the dump in relation to the slope of the land and location of rivers. Maybe something more daunting about the Kettleman city dump is its location to the California aqueduct, which runs near Kettleman city. This aqueduct bring water from northern to southern California, giving water to millions, and if the site is expanded, one important question may be is it possible for waste to taint the water travelling in the California aqueduct. But in the end, it is necessary to have a toxic waste dump, and GIS is an important tool in determining the desirability of the land on which the dump is located, and if the site needs to be moved because of the detrimental side effects it has upon the nearby population.

Mid-Term - Lab 5

By mapping the location of the marijuana dispensaries that are eligible and ineligible to remain in business, as well as mapping the locations of schools, parks and libraries, I have come to the conclusion that this ordinance should not be passed. The evidence I point to in this conclusion is the discrepancy between the locations of schools parks and libraries, and the allowance of some businesses to remain open. In the map of Marijuana Dispensaries in the City of Los Angeles, there are several instances of marijuana dispensaries being allowed to remain open while within a 1000 foot buffer of a school, library or park, while some marijuana dispensaries are being closed, though they are not within this buffer zone. This could possibly become a court issue or case of perceived discrimination or bias among the city council, possibly resulting in multiple lawsuits.

If the city council wishes to limit the amount of marijuana dispensaries within city limits, I advise a few more tactics or regulations. First enforce the 1000 foot buffer, but in a more fair way as to eliminate the possibility of court cases against the city for discrimination or bias, but also enforce drug-free zones, and close down dispensaries built during the marijuana dispensary moratorium when new dispensaries were not allowed to open within city limits. Also, another tactic may be to threaten the use of federal law, as marijuana is legal under California law, not United States law. Overall the ordinance has the right intentions and foundation, but needs to be reworked in order to benefit the citizens of the city of Los Angeles more effectively.

Data for Libraries was found at http://www.lapl.org/branches/

Data on dispensaries was found at http://cityclerk.lacity.org/cps/pdf/preliminaryResults08-25-10.pdf

Data for shapefiles was found at http://gis.ats.ucla.edu//Mapshare/Default.cfm

Lab 4 - Iraq Map

Lab 3 - Geocoding

For this project I decided to contact my father for data, as before this quarter began he asked for me to make a map for his work, so he could use it to possibly streamline or increase efficiency within his division. My father’s job is to locate and assist older adults in Orange County who have mental health issues or disabilities, and to provide assistance if needed. His employees, in this map called caseworkers, are assigned to individuals and are responsible for visiting the different clients to make sure they are maintaining a healthy lifestyle, and to assist them if they request or require counseling or doctor’s visits.

To maintain confidentiality, the addresses are off by a few streets, but the locations of the clients are near their respective locations. The clients are colored by their individual caseworker, listed in the legend. Alongside the client list is the list of individual clinics and treatment centers.

This data can be used for several things. First my father can locate which clients are being treated by which caseworker, and he can use this information to see how much driving the caseworkers must do, and could potentially re-assign caseworkers in order to save gas and increase efficiency. Second, my father can use this information to see the locations of clients in respect to their proximity to different treatment centers and clinics. Overall this map is practical in its design, and will be used to solve real problems, affecting care to different people, as well as creating real business solutions.

Below is the final product sent to my father.