Monday, January 26, 2015

Invasive Saltcedar (Tamarisk spp.) Distribution Mapping Using Multiresolution Remote Sensing Imagery

Saltcedar is a type of invasive species that has taken hold in the South and Southwestern United States. It originally came to the United States from Europe and Asia in the early 19th Century. It was brought by early settlers on purpose and by accident.  This research analysis of saltcedar looks at these populations through distribution mapping using multiresolution remote sensing imagery. It was achieved this through two types of analyses. First was five pixel-based classification were used through Quickbird and AISA.  The second analyses were done using Landsat TM imagery. The purpose of this analysis is to determine the distribution and density of saltceder populations in the United States, because of its destructive potential on native ecosystems.  

The results of this analysis showed that one type of process worked better than the other. AISA hyperspectral imagery performed better than other systems at mapping saltcedar populations in the South and Southwest. AISA outperformed Quickbird by roughly 10 percent. That 10 percent is in terms of accuracy of placing saltcedar in the correct place. All of the analyses showed a large distribution of saltcedars in local ecosystems.  This was able to show the best systems for mapping invasive species in the environment.  

Wang, L., Silván-Cárdenas, J. L., Yang, J., & Frazier, A. E. (2013). Invasive Saltcedar (Tamarisk spp.) distribution mapping using multiresolution remote sensing imagery. The Professional Geographer, 65(1), 1-15.

System,Science,and Studies

Chapter 1 basically explains what GIS is and how we as human beings use its technology in our everyday life. It also describes the origin of the GIS technology which was created in the mid 1960's in Canada. It was named the Canadian Geographic Information system or CGIS.  It also explains in great detail the different branches of technology that utilize the systems resources the most. Some say that this is the new way of solving real world problems with technology. Chapter one also briefly informs the readers the anatomy of the GIS database, meaning that it informs us how important the internet is to the operators of GIS. A company called ArcGIS is the number one user of the GIS database. Did you know that the GIS database was priced at over 5.9 billion dollars!! The five main components of GIS are also listed in this chapter. They are:The Internet, The users hardware, The software that runs on the users computer, The anatomy of the database, and finally the people who design, maintain, and run the system. Chapter one not only explains the technology side of GIS, but it also tell us about the business side of the system. Meaning how does this company turn a profit and there annual ratings.

Pictured above is Roger Tomlinson. The inventor of the first Canadian Geographic Information System 
I learned that the internet allows users access to specific functions that are provided by remote sites. The GIS world is highly influenced by the publishing industry which includes magazines, books, and journals. The first courses in GIS were offered in universities in the early 1970's, often as an overgrowth of courses in cartography and remote sensing. Did you know that in 1992 the term geographic information science was coined by Michael Goodchild in a paper he published. The one question that frequently is asked about the GIsystem is the system reliable enough for it to be used in geography. Many geographers are very skeptical about the GIsystem and still question its consistency

White rock Micro Heat islands

This blog stands out as it depicts the effect the suns rays heat and cool the earth and many of the contributing or off-setting factors. The author used thermal radar imaging to see where and why some places radiated more heat or why the areas are able to stay cool. A degree change of 6 to 11 is quite significant and can be the difference from a desert and a forest. His finding showed that the coolest areas were highly wooded and older building that had a lot of cover that absorb and radiates the heat from the Sun. Roofs of building bare ground and concrete are the biggest reflectors of heat and trap them. Greenery can off set much of the heat but not enough, the forest to the north maintains the coolest temperatures while the apartments and urbanized to the west and south have substantially hotter temperatures.

Spatial analysis on neighborhood effects and voter turn-out in College Station, Texas

     Through a spatial analysis of voter turnout and the " neighborhood effect" within College Station, TX, draws a relationship between voting at a precinct level with voters and nonvoters in three locations and the outcomes within their communities. The purpose of this spatial analysis is to examine the outcome of what happens within a local community (whether it be negative or positive) based on how socio-politically participatory the residents are. When analyzing three past referendums that were voted on within College Station, one in 1995 regarding a $10 million issuance for infrastructure in order to "reconstruct" the community, another in 1997 that initiated a prevention of construction of a City Convention Center, and one more in 1999 that was initiated in order to reopen a city street that was closed due to "the high nuisance through traffic."

           In 1995, the referendum initiated by the city council of College Station was the least cared about since it was the least controversial. Since it is completely appropriate to spend tax dollars on improvements around the city, there was no controversy. The referendum would be an overall improvement for everyone within the community making  a clear impact upon the voter turnout. Since the neighborhood effects would be an improvement overall, the voter turnout for the referendum to pass was the obvious winner.

                The results of the referendum initiated by voters in 1997 provide a more controversial argument due to a skeptical community regarding tax dollars going to a city convention center. Although the creation of the city convention center would stimulate economic growth and create new jobs, many residents argued against the city council. Many people opposed the convention center however; an equal amount of people favored as well. The referendum was passed as well but with a slimmer margin due to people being split upon the decision.

                The most controversial referendum in College Station was initiated in 1999 to force the city to reopen Munson Avenue. In order to greatly increase traffic on a street in one of the city's most attractive neighborhoods, many people argued back and forth opposing and in favor for the opening of the street Residents of Munson even being attacked by being called elitists by voters. Strong advertisement and media coverage opened this referendum to be a significance among all people within the community. The referendum, however, was passed "by a near 2-1 ratio" due to the strong media interest showing that Munson Avenue was perpendicular to the TAMU campus's south side. People in the voting precincts south of TAMU saw closing of Munson Avenue as a restriction of their traveling routes to TAMU. The voter turnout of this referendum was scattered and cluster which makes the effects of the neighborhood scattered and clustered as well.

                In conclusion, neighborhood effects in local politics are heavily influences by distribution of actual voters. The outcome among the community will be based on how many people oppose or favor what they want due each individual's self-interest.

Sunday, January 25, 2015

Geodesy and Geodetic Methods

What is Geodesy? 
Due to technology, the knowledge of Earth's shape and landscapes has changed over the years. Thanks to geodesy, studying these changes has become easier and more precise. Geodesy focuses on Earth's size, orientation, shape, and gravitational field as well as fluctuations in these values.

Modern Geodesy
Advances in modern technologies, such as GPS and synthetic aperture radar satellites, have allowed geodetic research to become even more precise. Modern geodesy gathers information using four basic techniques: positioning of geodetic instruments, altimetry, interferometric synthetic aperture radar (InSAR), and gravity studies. Efficient positioning of radio telescopes, satellite lasers, and GPS is necessary for precise geodetic measurements. Altimetry measurements gather data through changes in elevation instead of measuring 3D changes by alternative positioning techniques. Altimetry satellites shoot pulses at Earth's surface in order to gain ground measurements. InSAR uses SAR observations to produce digital elevation models. Gravity studies use satellite orbits to measure gravitational changes because satellite orbits are very sensitive to gravitational changes which makes them useful when determining the shape of the Earth. 

Applications (Global/Local) and Societal Implications

Geodesy can be used on a global scale to calculate global issues such as water budgets for each country. 
Using satellites to measure sea levels helps determine these figures. 

The same research methods can be applied on a local scale.Pictured above shows the use of geodetic 
tools to gather information about river and lake water levels in the Congo. This helps give insight 
into available ground water. 

As a result of these technological advances and their implementations, people can be better informed about the societal impacts of small changes in Earth's environment. For example, the severity of hazards that pose threats to coastal regions, such as flooding due to rising sea levels, can be measured more accurately using geodetic methods. The precision of geodetic measurements and the variety of applications for geodetic data make geodesy make it essential for understanding further many of the Earth's processes and humanity's impact on those processes. 

Wdowinski, S., & Eriksson, S. (n.d.). Geodesy in the 21st Century. Eos, Transactions American Geophysical Union, 153-153.

Local Food Systems

Globalization and industrialization of the food industry has forever changed the way of life for most people and led to a lack of ability for people living in urban centers to eat locally and organically. Eating locally is seen as the solution to the globalized food system and the issues that it has brought to our society. The common theme of urban centers is a lack of green space and ways for people to get fresh foods. And this lack of fresh foods is commonly centralized around the parts of cities with the lowest annual incomes. However, in Philadelphia, progress has been made and about 50% of the new community gardens are located in the <$18,000/year income districts (Fig. 2).

In mapping the local food system in Philadelphia, the amount of "food miles" that food travels from its source of production to the consumer was looked at and most of the food was determined to be local. Yet, the administrative boundaries of what is considered to be local may be skewed seeing as the average distance traveled is still 61 miles. With this in mind, it can still be said that progress is being made with community gardens filling some of the food availability gaps in low income neighborhoods. Using mapping technologies to determine distances of populations from food producers as well as finding available land that could be utilized for further development of the local food system, the future integration of local food production into the existing food industry is looking more promising than ever.

Kremer, P., & DeLiberty, T. L. (2011). Local food practices and growing potential: Mapping the case of Philadelphia. Applied Geography31(4), 1252-1261.

VGI as Big Data

Volunteered Geographic Information (VGI) is a term that can also be called "big data." Applications such as Foursquare utilize and are involved in the creation of big data. However, this is just one of the many tools that companies and businesses use to track certain data about their customers. The companies use the data/geodemographics to analyze customers, target groups, and ideal sale regions for the company's benefits.
This is a graph depicting movement using the Twitter application.

This type of data is coined "volunteered" simply because the users of the applications are considered volunteers by partaking in the use of the application. This information is collected through geographical datasets that are generated by the users and are put to use by companies and businesses. VGI can be considered a commodity in this aspect, because data is analyzed and applied for economic decision-making processes. One main problem with VGI is that the datasets don't allow for any definitive and respected interpretation of what is represented. There is a lack of knowledge and understanding about motives and contexts of the users, so a well informed analysis of the data is hardly possible. Perhaps the other main problem is the argument of whether the information is truly "volunteered" or not. Users go online and utilize the uses of the applications that are popular today, such as Twitter, Foursquare, and Flickr. It is argued that they are not using those applications in order to provide information to a third party for the process of geodemographic profiling. In contrast, it is argued that they simply wish to participate in the everyday uses of the applications.
This image shows tourist density that is calculated from the Flickr database.

Fischer, F. (2012). VGI as Big Data: A new but delicate geographic data-source. GeoInformatics15(3), 46-47.

Sunday, October 5, 2014

White Rock Lake and Micro Urban Heat Islands

Cathy Aniello, Ken Morgan, Arthur Busbey, and Leo Newland used LANDSAT TM and GIS to map micro-urban heat islands in Dallas, Tx. Specifically, the researchers looked at the White Rock Lake area which has diverse land cover including impervious cover, bare soil, grass, trees, and apartment buildings. Micro urban heat islands are different than heat islands. Heat islands are areas generalized as having higher temperatures than the surrounding rural areas. Micro urban heat islands (MUHI) are hot-spots within the city urban heat island. These researchers believed that increased tree cover would offset the effects of these MUHIs. They looked at satellite temperature readings from LANDSAT TM and found that areas with trees were not only cooler, but had a radiative cooling effect that extended well beyond the tree canopy. They found that the MUHIs also had a radiative heat effect. Interestingly, older apartments and housing areas were significantly cooler than newer ones due to their increased tree cover. The hottest areas in White Rock Lake were land uses associated with impervious cover such as a warehouse district, asphalt parking lots and roads, and the new apartment complexes on the West side of the lake. Big areas of bare soil and grass around the lake were also hot spots. The coolest areas were those with the most tree cover such as the heavily forested area to the North of the lake and the older apartments and residential areas and White Rock Lake. This data reinforces the idea that increased tree cover leads to cooling of surrounding areas and could be used to combat the heat island effect. The MUHIs are an average of 5 to 11 degrees Celsius warmer than their surroundings. Increasing tree cover in urban areas would not only help reduce temperatures but would also help sequester more carbon emissions and other pollutants (which are abundant in urban settings), help prevent runoff and soil erosion, as well as create visually pleasing green spaces.  

Aniello, C., Morgan, K., Busbey, A., & Newland, L. (1995). Mapping micro-urban heat islands using Landsat TM and a GIS. Computers & Geosciences,21(8), 965-969.

Measuring Insolation and Soil Temperature in the Rocky Mountains

Insolation, incoming solar radiation, is essential for life on Earth and is integral to physical, chemical, and biological processes in our world. Insolation has direct effects on water and energy balances and therefore indirectly affects evapotranspiration, photosynthesis, wind conditions, snow melt, as well as air and soil temperature. In this study the main focus was soil temperature. Pinde Fu and Paul M. Rich used digital elevation models (DEMs) and insolation models that accounted for a variety of variables including elevation, atmospheric conditions, and varied topography to create an insolation model for an area near the Rocky Mountain Biological Laboratory in Colorado. 
Digital Elevation Model for the study area
Most interpolation methods to this point are for use on broad scales such as country or continent, but a finer method for smaller areas is not as common. Variables such as elevation, surface orientation (slope), and vegetable cover end up creating a gradient of insolation that changes with the topography. Most methods of interpolating insolation require tremendous data input and computation which in turn require expensive and sophisticated software. Other methods tend to be inaccurate and don’t account for all the aforementioned variables. The goal of this study was to create high resolution temperature maps for the study area using a few measurements from high resolution insolation models. They used Solar Analyst to derive average solar conditions/insolation for the study area. They combined physical soil temperature data samples with their temperature model to calculate temperature gradients based on elevation, topography, and vegetation cover. The result was an accurate and high resolution temperature map of their study area. The temperature and insolation data have applications in both agriculture and forestry. Looking at and understanding the levels and distribution of inoslation over different topographies could be used to determine the best areas to plant crops or which areas of forest are at risk for fires.

 Finished soil temperature map

Fu, P., & Rich, P. M. (2002). A geometric solar radiation model with applications in agriculture and forestry. Computers and electronics in agriculture37(1), 25-35.

Wednesday, October 1, 2014

L’île d’Yeu, Un Espace Convoité : Développement et Aménagement

Comme pour mon dernier article, nous faisons un bond de près de 20 ans en arrière pour lever le voile sur cette étude. Il est question cette fois d’une charmante petite île sur la côte atlantique française, l’île d’Yeu. Cette île, comme la grande partie de la côte atlantique française, bénéficie d’une économie liée à la pêche depuis des années. Les changements apportés à cette île durant la dernière quarantaine d’années ont été très important et c’est pour cela que Patrick Pottier et Marc Robin ont trouvé intéressant de cartographier ces changements à l’aide du SIG.

Ils leur alors fallu prendre en compte un grand nombre de composantes pour construire un modèle simple d’organisation spatiale, d’organisation du territoire. Les deux composantes principales sont séparées en deux sphères interne et externe, où la sphère interne n’est autre que le paysage urbain, agricole et la végétation urbaine, alors que la sphère externe représente le milieu physique, la topographie, l'altitude et le contrôle anthropique. Ces informations ont été récoltées au travers des années afin de créer une carte représentative de l’année 1951 et une de l’année 1990.
Au final, une simple délimitation par polygone est utilisée pour cartographier les zones occupées par l’urbain et l’agricole.

Evolution de l'espace urbain

Evolution de l'agriculture

Deux cartes qui ne sont pas forcément compliquées à réaliser. Ce qui est plus complexe par contre, c’est toute la problématique que montre ces cartes. En effet, lorsque l’on analyse ces cartes, la perte de l’espace agricole au bénéfice de l’espace urbain. En effet, nous pouvons voir par rapport aux années une consommation de l’espace urbain sur l’espace agricole. Tout cela a commencé en 1951 avec l’explosion urbaine de l’île jusqu’en 1995 où 30% du territoire est occupé. C’est d’ailleurs avec ces statistiques que l’on comprend les raisons des changements sur l’île d’Yeu. Effectivement, c’est île a su tirer profit de sa situation favorable au tourisme alors que 51% de ses habitations sont des habitations secondaires.

En conclusion, le système d’information géographique aide à démontrer que l’île a bénéficié d’une économie touristique à la place de se concentrer sur les ressources naturelles. Cela explique l’expansion urbaine aussi importante en défaveur des espaces agricoles.