Tornadoes are one of Mother Nature’s deadliest phenomena. They affect a large region of the United States. The risk of tornadoes is contingent on dynamic atmospheric conditions that are most likely during spring but which can occur anytime of the year, making the storms challenging to forecast. Using geographical information systems (GIS), a web-based spatial decision support system (SDSS) was created to help understand the spatial dimension of tornado risk assessment. The risk values are calculated using Tornado Days rather than taking a crude density measurement. The SDSS hosts GIS web services that are displayed on an Adobe Flex application. The web application allows users to view, research, query and extract information from the attributes of the GIS files. There is also a dynamic risk tool which gives users the ability to click anywhere inside the study area and get the percentage of risk that a tornado will occur within 25 miles of that very point. The web application eliminates users and viewers from conducting their own research and GIS work. In addition, automated updating models and macros were created to update the tornado database on an annual basis.

There is a need to integrate large-scale database, high-performance computing engines and geographical information system technologies into a user-friendly web interface as a platform for data visualization and customized statistical analysis. We present some concepts and design ideas regarding dynamic data storage and extraction by making use of open-source computing and mapping technologies. We implemented our methods to the Kentucky Mesonet automated weather mapping workflow. The main components of the work flow includes a web based interface, a robust database and computing infrastructure designed for both general users and power users such as modelers and researchers.

No description available.

Shallow lake wetlands, for which aquatic plants (macrophytes) and water clarity are the key indicators of ecological status, provide valuable services to wildlife and humanity. Conservation of these ecosystems requires development of rapid and large scale monitoring strategies, where remote sensing and Geographic Information Systems (GIS) can be advantageous. In this study, high spatial resolution Quickbird and IKONOS and medium spatial resolution Landsat and Aster images were used for monitoring the aquatic plants and water clarity in Lakes Mogan and Eymir. Classification of emergent plants with high spatial resolution data yielded overall accuracies greater than 90% for both lakes, while overall accuracies obtained from the medium spatial resolution data ranged between 80% and 93% for Lake Mogan and between 70% and 78% for Lake Eymir. It was found that there was 23ha reed bed loss in Lake Mogan between 2002 and 2005 and an additional 14ha was lost between 2005 and 2006. In Lake Eymir, no significant change in reed bed area was detected from high spatial resolution images / however medium spatial resolution images revealed 8ha of change which was attributed to the presence of mixed pixels due to low resolution. The overall accuracies for submerged plant coverage classification from Quickbird images in Lake Mogan were 83% (2005) and 79% (2006) and for classification of submerged plants species were 72% (2005) and 69% (2006). Moreover, it was found that blue band together with the ratio of red band to blue band, were the best predictors of Secchi disc depth.

The purpose of this study is to evaluate and to compare the results of bivariate statistical analysis conducted with three different data sets in Geographical Information Systems (GIS) based landslide susceptibility mapping applied to the Devrek region. The data sets are created from the seed cells of crowns and flanks, only crowns, and only flanks of the landslides by using 10 different parameters of the study area. To increase the data dependency of the analysis, all parameter maps are classified into equal frequency classes based directly on the percentile divisions of each seed cells data set. The resultant maps of the landslide susceptibility analysis indicate that all data sets produce acceptable results. In each seed cell data set analysis, elevation, lithology, slope, aspect and drainage density parameters are found to be the most contributing factors in landslide occurrences. The results of the three data sets are compared by Seed Cell Area Index (SCAI). This comparison shows that the crowns data set produces the most accurate and successful landslide susceptibility map of the study area.

Disputats. Rheinische Friedrick-Wilhelms-Universität, 2001.

There are 34 state-supported historic sites that are managed by the Texas Historical Commission (THC) and the Texas Parks and Wildlife Department (TPWD). These sites have been acquired over the years with various justifications and acquisition histories and are not a planned system of historic sites. With the rapidly changing demographics in Texas, it is clear that new strategies need to be developed so that these sites better represent the history of all Texans. The thesis investigation begins with a history of diversity initiatives within the preservation movement. Next, I present an innovative method for identifying potential areas of focus for diversity initiatives at state historic sites using Geographic Information Systems (GIS). I developed a spatial analysis methodology to quantify the level of diversity of the web content of each of the 34 state historic sites. Each historic site’s web site was then ranked according to its relevance to four ethnic groups: African Americans, Hispanics, Asians and Native Americans. Additionally, I generated population maps, descriptive maps, and analytical maps in order to understand how historic sites interact with the surrounding population. Finally, I present a set of strategies for existing state historic sites that will provide greater diversity in interpretative techniques and promotion. The goal of the GIS-based spatial analysis and the subsequent development of strategies aimed at targeted sites is to broaden the appeal of historic sites to a more diverse audience. / text

Στο πρώτο κεφάλαιο αναπτύσσονται οι έννοιες Γεωδαισία, Γεωδαιτικό ή τοπογραφικό δίκτυο, τα είδη των δικτύων, τα προβολικά συστήματα, τα διεθνή και τα ελληνικά γεωδαιτικά συστήματα αναφοράς καθώς και η μεταξύ τους μαθηματική σχέση. Στο δεύτερο κεφάλαιο αναφέρονται ο ορισμός και τα είδη του Γεωγραφικού Συστήματος Πληροφοριών, τα δομικά του στοιχεία, η οργάνωσή του, οι εφαρμογές και δυνατότητές του. Επίσης ιδιαίτερη έμφαση δίνεται στη διασύνδεση του Γ.Σ.Π με την ευρυζωνικότητα, γεγονός το οποίο αναδεικνύει την σημαντικότητα ύπαρξης των GIS(Γ.Σ.Π). Στο τρίτο κεφάλαιο αναλύεται το πρόγραμμα που χρησιμοποιήθηκε στην υλοποίηση, δηλαδή το Quantum GIS, ενώ ακολουθούν οι ψηφιακοί χάρτες καθώς και οι αναλυτικές αναφορές σχεδιασμού τους, οι οποίοι κατασκευάστηκαν με χρήση του QGIS. Η παραπάνω ανάλυση αναφέρεται στους δήμους Πύργου, Αμαλιάδος, Πάτρας, Ρίου, Αιγίου, Αγρινίου, Ναυπλίου και Μεσολογγίου. Στο τέταρτο κεφάλαιο αναπτύσσονται δύο αλγόριθμοι εφαρμογής: ένας για την ανίχνευση του περικλειόμενου τριγώνου(με κορυφές ασύρματα κέντρα) δοθέντος συγκεκριμένου σημείου και ένας για την εύρεση της διαδρομής από δοθέν σημείο έως τον πλησιέστερο κόμβο ενός δικτύου οπτικών ινών. Στο πέμπτο κεφάλαιο παρουσιάζονται τα συμπεράσματα της διπλωματικής εργασίας και ακολουθεί η βιβλιογραφία που χρησιμοποιήθηκε. / -

The Homol'ovi region of northeastern Arizona was home to a dense prehistoric population with strong, archaeologically-visible ties to the Hopi Mesas. As an ancestral Hopi residential area, this region is an important part of the Hopi cultural landscape utilized contemporarily by Hopi people for religious and resource procurement purposes. However, while previous research indicates that the Cottonwood Wash drainage formed an important component of the Homol'ovi landscape, the archaeology of the wash and its adjacent uplands is poorly understood. This research adopts a two-pronged approach to assessing the efficacy of GIS analysis for interpreting the spatial distribution of archaeological sites within the Homol'ovi landscape. The deductive approach draws on principles of cultural landscape theory to construct a descriptive model of dimensions of Hopi land use on the basis of ethnographic documentation and Hopi traditional history. This model is applied to a database composed of survey data collected from the Cottonwood Wash vicinity and data from the Homol'ovi Research Program's survey of Homolovi State Park. The model is then operationalized through GIS analysis of site distributions, and the efficacy of the model for predicting the location of different types of prehistoric land use is evaluated. The second, inductive, approach examines site distribution relative to patterns of visibility and movement in the Homol'ovi region and identifies areas for the refinement of spatial data associated with shrines and petroglyphs in the region. On the basis of this two-pronged approach, a research strategy iteratively incorporating deductive and inductive analyses, coupled with the use of participatory approaches, is recommended for future research.

There are a number of decision making problems in which Geographical Information System (GIS) has employed to organize and facilitate the procedure of analyzing the problem. These GIS-based decision problems which typically include a number of different criteria and alternatives are generally analyzed by Multicriteria Decision Analysis (MCDA).Different locations within a geographical area represent the alternatives by which the overall goal of the project is achieved. The quality of achieving the goal is evaluated by a set of criteria which should be considered in the work. Analytic Hierarchy Process (AHP) which is a powerful method of MCDA generally can organize spatial problems and decides which alternatives are most suitable for the defined problems. However due to some intrinsic uncertainty in the method, a number of authors suggest fuzzifying the method while others are against fuzzification of the AHP. The debate over fuzzifying AHP is going on and attempt for finding that was mostly in theory, and little, if any; practical comparison between the AHP and fuzzified AHP has done. This work presents a practical comparison of AHP and fuzzy AHP in a GIS-based problem, case study, for locating a dam in Costa Rica, considering different criteria. In order to perform the AHP and fuzzy AHP in the GIS-based problem and calculating weights of the criteria by the methods, some computer codes have written and developed in MATLAB. The comparisons between the AHP and fuzzy AHP methods are done on result weights and on the result final maps. The comparison between the weights is repeated on different levels of uncertainty in fuzzy AHP then all the results are compared with the result of AHP method. Also this study for checking the effect of fuzzification on results is suggested Chi-Square test as a suitable tool. Comparisons between the resulting weights of the AHP and fuzzy AHP methods show some differences between the methods. Furthermore, the Chi-Square test shows that the higher level of uncertainty in the fuzzy AHP, the greater the difference in results between the AHP and fuzzy AHP methods.