A Clustering Approach for Protecting GIS Vector Data

The availability of Geographic Information System (GIS) data has increased in recent years, as well as the need to prevent its unauthorized use. One way of protecting this type of data is by embedding within it a digital watermark. In this paper, we build on our previous work on watermarking vector map data, to improve the robustness to (unwanted) modifications to the maps that may prevent the identification of the rightful owner of the data. More specifically, we address the simplification (removing some vertices from GIS vector data) and interpolation (adding new vertices to GIS data) modifications by exploiting a particular property of vector data called a bounding box. In addition, we experiment with bigger maps to establish the feasibility of the approach for larger maps

Geographically intelligent disclosure control for flexible aggregation of census data

This paper describes a geographically intelligent approach to disclosure control for protecting flexibly aggregated census data. Increased analytical power has stimulated user demand for more detailed information for smaller geographical areas and customized boundaries. Consequently it is vital that improved methods of statistical disclosure control are developed to protect against the increased disclosure risk. Traditionally methods of statistical disclosure control have been aspatial in nature. Here we present a geographically intelligent approach that takes into account the spatial distribution of risk. We describe empirical work illustrating how the flexibility of this new method, called local density swapping, is an improved alternative to random record swapping in terms of risk-utility

Land Use Planning and Vernal Pool Conservation in a Southern Maine Town

In this dissertation I investigate the impacts of both growth management regulations and vernal pool protection regulations on landscape permeability for wood frogs (Rana sylvatica), a vernal pool-obligate species. Motivated by new legislation in Maine (USA) to protect vernal pools and the species that depend on them, I combined a spatially-explicit economic model of the conversion of undeveloped parcels to residential use with a landscape permeability model for wood frogs. I estimated the economic model using a Bayesian Gibbs Sampler to account for spatial error dependence and used the results to predict future landscape patterns in a focal town, Falmouth, Maine, under different growth management and vernal pool buffer policies. Through a series of simulated vernal pool distributions, I also examine the importance of the degree of clustering of pools on the effectiveness of pool buffers. I also produced buildout scenarios for the focal town assuming cluster zoning and conservation zoning. I analyzed each of these predicted landscapes using the landscape permeability model to assess the resulting functional connectivity of the future landscapes at three scales based on the life cycle of wood frogs. Specifically, I examined connectivity between breeding pools, between breeding pools and non-breeding habitat, and between clusters of breeding pools. The results suggest that vernal pool buffers offer moderate protection at the breeding pool level but less protection to amphibians migrating beyond breeding pools. Open space requirements in subdivisions also appear capable of improving permeability for migrating amphibians, but they are generally less effective than breeding pool buffers. Nonetheless the differences in permeability across different levels of open space and the interaction between buffers and open space requirements suggest that different land use planning and open space policies may alter the effectiveness of buffer zones across space and across jurisdictions. The results suggest the need for a multi-scale approach to pool-breeding amphibian conservation and point to conservation zoning as a promising multi-scale approach

Indigenous voices in climate change adaptation

AbstractThis project investigated how the deep knowledge of the Yorta Yorta people can be used to strengthen their participation and influence in the complex national and regional processes that determine how their traditional lands, which are in the highly-contested Murray-Darling Basin, are managed, leading to improved adaptation decisions both for the Yorta Yorta and the wider community.Through discussions with the Yorta Yorta over several years, the approach developed for the project was the creation of a Geographical Information System (GIS) mapping framework containing both Yorta Yorta knowledge and more conventional knowledge. GIS allows for mapping and layering of different types of data, allowing the Yorta Yorta to access and present their knowledge in ways that relate to Western decision-making processes. To do this, the project had four components:1. Development and testing of protocols and methodology for the collection and protection of Yorta Yorta knowledge. This was carried out through an intergenerational process, whereby Yorta Yorta youth were trained in cultural data collection techniques, and they interviewed Elders to capture the knowledge.2. Building of a GIS framework to integrate both the Yorta Yorta knowledge and more conventional data about the climate, hydrology and biodiversity of the Yorta Yorta area. For the first time this pulled together all of the conventional information normally used as a basis for natural resource management decisions. In addition, because the GIS database has been created and is owned by the Yorta Yorta means that they have something of value to bring to the discussions, so that they are able to participate in those discussions on equal terms.3. Exploration of the views of the broader community in the region regarding management of the region and adaptation alternatives through a stakeholder consultation process. The consultation identified the potential for greater use of science as a neutral arbiter in issues such as management of the Murray-Darling Basin, but even more important is the need for genuine, deep, open-minded dialogue with the community at all stages of decision-making, particularly at an early stage before proposals are put forward and views become entrenched.4. Identification of broader lessons for improving adaptation of First Nations communities in Australia from the experience of the Yorta Yorta and other communities around the country, through a national workshop. The key conclusion of the workshop was the urgent need to empower First Nation communities to make their own assessments and decisions on the best ways for them to respond to climate change.The project raised community awareness and knowledge and energised the Yorta Yorta youth to take an interest in their history and culture, and in the climate challenges facing their community. Overall the project has been a successful pilot demonstration of the utility of a GIS database to integrate Indigenous and conventional knowledge for better natural resource management outcomes and the project has increased the knowledge and capacity of the Yorta Yorta to engage in effective natural resource management and decision-making.Please cite this report as:Griggs, D, Lynch, A, Joachim, L, Zhu, X, Adler, C, Bischoff-Mattson, Z, Wang, P, Kestin, T 2013  Indigenous voices in climate change adaptation: Addressing the challenges of diverse knowledge systems in the Barmah-Millewa, National Climate Change Adaptation Research Facility, Gold Coast, pp.71AbstractThis project investigated how the deep knowledge of the Yorta Yorta people can be used to strengthen their participation and influence in the complex national and regional processes that determine how their traditional lands, which are in the highly-contested Murray-Darling Basin, are managed, leading to improved adaptation decisions both for the Yorta Yorta and the wider community.Through discussions with the Yorta Yorta over several years, the approach developed for the project was the creation of a Geographical Information System (GIS) mapping framework containing both Yorta Yorta knowledge and more conventional knowledge. GIS allows for mapping and layering of different types of data, allowing the Yorta Yorta to access and present their knowledge in ways that relate to Western decision-making processes. To do this, the project had four components:Development and testing of protocols and methodology for the collection and protection of Yorta Yorta knowledge. This was carried out through an intergenerational process, whereby Yorta Yorta youth were trained in cultural data collection techniques, and they interviewed Elders to capture the knowledge.Building of a GIS framework to integrate both the Yorta Yorta knowledge and more conventional data about the climate, hydrology and biodiversity of the Yorta Yorta area. For the first time this pulled together all of the conventional information normally used as a basis for natural resource management decisions. In addition, because the GIS database has been created and is owned by the Yorta Yorta means that they have something of value to bring to the discussions, so that they are able to participate in those discussions on equal terms.Exploration of the views of the broader community in the region regarding management of the region and adaptation alternatives through a stakeholder consultation process. The consultation identified the potential for greater use of science as a neutral arbiter in issues such as management of the Murray-Darling Basin, but even more important is the need for genuine, deep, open-minded dialogue with the community at all stages of decision-making, particularly at an early stage before proposals are put forward and views become entrenched.Identification of broader lessons for improving adaptation of First Nations communities in Australia from the experience of the Yorta Yorta and other communities around the country, through a national workshop. The key conclusion of the workshop was the urgent need to empower First Nation communities to make their own assessments and decisions on the best ways for them to respond to climate change.The project raised community awareness and knowledge and energised the Yorta Yorta youth to take an interest in their history and culture, and in the climate challenges facing their community. Overall the project has been a successful pilot demonstration of the utility of a GIS database to integrate Indigenous and conventional knowledge for better natural resource management outcomes and the project has increased the knowledge and capacity of the Yorta Yorta to engage in effective natural resource management and decision-making

Discovering private trajectories using background information

Trajectories are spatio-temporal traces of moving objects which contain valuable information to be harvested by spatio-temporal data mining techniques. Applications like city traffic planning, identification of evacuation routes, trend detection, and many more can benefit from trajectory mining. However, the trajectories of individuals often contain private and sensitive information, so anyone who possess trajectory data must take special care when disclosing this data. Removing identifiers from trajectories before the release is not effective against linkage type attacks, and rich sources of background information make it even worse. An alternative is to apply transformation techniques to map the given set of trajectories into another set where the distances are preserved. This way, the actual trajectories are not released, but the distance information can still be used for data mining techniques such as clustering. In this paper, we show that an unknown private trajectory can be reconstructed using the available background information together with the mutual distances released for data mining purposes. The background knowledge is in the form of known trajectories and extra information such as the speed limit. We provide analytical results which bound the number of the known trajectories needed to reconstruct private trajectories. Experiments performed on real trajectory data sets show that the number of known samples is surprisingly smaller than the actual theoretical bounds

Coastal erosion and accretion in Pak Phanang, Thailand by GIS analysis of maps and satellite imagery

Coastal erosion and accretion in Pak Phanang of southern Thailand between 1973 and 2003 was measured using multi-temporal topographic maps and Landsat satellite imageries. Within a GIS environment landward and seaward movements of shoreline was estimated by a transect-based analysis, and amounts of land accretion and erosion were estimated by a parcel-based geoprocessing. The whole longitudinal extent of the 58 kilometer coast was classified based on the erosion and accretion trends during this period using agglomerative hierarchical clustering approach. Erosion and accretion were found variable over time and space, and periodic reversal of status was also noticed in many places. Estimates of erosion were evaluated against field-survey based data, and found reasonably accurate where the rates were relatively great. Smoothing of shoreline datasets was found desirable as its impacts on the estimates remained within tolerable limits

Exploring the effectiveness of geomasking techniques for protecting the geoprivacy of Twitter users

With the ubiquitous use of location-based services, large-scale individual-level location data has been widely collected through location-awareness devices. Geoprivacy concerns arise on the issues of user identity de-anonymization and location exposure. In this work, we investigate the effectiveness of geomasking techniques for protecting the geoprivacy of active Twitter users who frequently share geotagged tweets in their home and work locations. By analyzing over 38,000 geotagged tweets of 93 active Twitter users in three U.S. cities, the two-dimensional Gaussian masking technique with proper standard deviation settings is found to be more effective to protect user\u27s location privacy while sacrificing geospatial analytical resolution than the random perturbation masking method and the aggregation on traffic analysis zones. Furthermore, a three-dimensional theoretical framework considering privacy, analytics, and uncertainty factors simultaneously is proposed to assess geomasking techniques. Our research offers insights into geoprivacy concerns of social media users\u27 georeferenced data sharing for future development of location-based applications and services