Application of a GIS-aided Method for the Assessment of Volcaniclastic Soil Sliding Susceptibility to Sample Areas of Campania (Southern Italy)

Natural Hazards, Published Online 20 April 2011

Sebastiano Perriello Zampelli, Eliana Bellucci Sessa, and Marco Cavallaro

“A significant part of Campania is extensively covered by volcaniclastic soils, deriving from the alteration of airfall-sedimented formations of layered ashes and pumices that were ejected by Campi Flegrei and Mt. Somma–Vesuvius during explosive eruptions. Where such soils cover steep slopes cut in carbonate bedrock, landforms depend essentially on the morpho-evolution of such slopes prior to the deposition of the volcaniclastic soils, because these are generally present only as thin veneers, up to a few meters of total thickness. Historical records and local literature testify that, in this part of Campania, landslides that originate on carbonate slopes covered by such soils and terminate at their foot or at gully outlets are frequent, following critical rainfall events. Such landslides can be classified as complex, occurring initially as debris slides, but rapidly evolving into debris avalanches and/or debris flows. The localization of the initial sliding areas (i.e. “sources”) on the slopes depends on both the spatial distribution of characters of the soil cover and the spatial distribution of the triggering rainfall events. It therefore appears reasonable to separate the two aspects of the problem and focus on the former one, in order to attempt an assessment of soil sliding susceptibility in the event of landslide-triggering rainfall. In this paper, some results of the application of a method aimed at such an assessment are presented. The method, called SLIDE (from SLiding Initiation areas DEtection), is based on the concept that, for a spatially homogeneous soil cover and a spatially homogeneous landslide-triggering rainfall sequence, different values of threshold slope gradient for limit equilibrium conditions exist, depending on morphological characters of the soil cover, such as its continuity and planform curvature. The method is based on the assessment of (1) soil cover presence, (2) discontinuities within soil cover, (3) slope gradients and curvature, by means of good resolution DEMs. It has been applied to sample carbonate slopes of Campania, where landslides originated either repeatedly or recently. Results are encouraging, and a soil sliding susceptibility map of a large area, based on a simplified version of method, is also presented.”

Modeling Spatial Accessibility to Parks: A National Study

International Journal of Health Geographics, Published 09 May 2011

Xingyou Zhang, Hua Lu, and James B. Holt

“Background: Parks provide ideal open spaces for leisure-time physical activity and important venues to promote physical activity. The spatial configuration of parks, the number of parks and their spatial distribution across neighborhood areas or local regions, represents the basic park access potential for their residential populations. A new measure of spatial access to parks, population-weighted distance (PWD) to parks, combines the advantages of current park access approaches and incorporates the information processing theory and probability access surface model to more accurately quantify residential population’s potential spatial access to parks.

“Results: The PWD was constructed at the basic level of US census geography – blocks – using US park and population data. This new measure of population park accessibility was aggregated to census tract, county, state and national levels. On average, US residential populations are expected to travel 6.7 miles to access their local neighborhood parks. There are significant differences in the PWD to local parks among states. The District of Columbia and Connecticut have the best access to local neighborhood parks with PWD of 0.6 miles and 1.8 miles, respectively. Alaska, Montana, and Wyoming have the largest PWDs of 62.0, 37.4, and 32.8 miles, respectively. Rural states in the western and Midwestern US have lower neighborhood park access, while urban states have relatively higher park access.

“Conclusions: The PWD to parks provides a consistent platform for evaluating spatial equity of park access and linking with population health outcomes. It could be an informative evaluation tool for health professionals and policy makers. This new method could be applied to quantify geographic accessibility of other type of services or destinations, such as food, alcohol, and tobacco outlets.”

A GIS-approach for Determining Permanent Riparian Protection Areas in Mato Grosso, Central Brazil

Applied Geography, Volume 31, Issue 3, July 2011, Pages 990-997

Peter Zeilhofer, Lunalva Moura Schwenk, Naomi Onga

“In this paper we propose a DEM-based GIS methodology for the identification and delimitation of riparian protection areas according to stream width. In Brazil, vegetation cover in buffer zones is monitored by mid-resolution satellite imagery, so our methodological approach includes procedures to ensure geometrical accuracy for multiple spatial layer overlay. For a study area in Mato Grosso, a sequence of DEM pre-processors was used to hydrologically correct a SRTM 90 m resolution digital elevation model. Then samples of river widths were obtained by measures using high-resolution IKONOS imagery and regressed against watershed contribution areas to define protection zone buffers. We propose a procedure to attribute the DEM-based width estimates derived from topographic maps and satellite imagery to the river networks. Validation using high-resolution IKONOS imagery indicates that the proposed methodology produces RMS errors of about 20 m on average for watercourses up to 600 m wide. This is a considerable improvement in protection area delimitation compared with current practice, particularly in headwater regions and along streams with widths of up to 200 m. Accuracy assessments indicate that environmental licensing procedures should include a tolerance of between 48% (<50 m) and 15% (200–600 m) of stream width, according to systematic errors included in the estimates.

“Highlights

  • SRTM DEM allows reliable river channel width estimates from less than 10 m up to about 600 m.
  • Contribution area size explains more than 94% of the variation in cross-section widths with a RMS error of about 20 m. Reach classification achieves an overall accuracy higher than 85%.
  • A GIS-procedure is proposed to attribute width estimates to the river networks derived from topographic maps and satellite image interpretation.
  • Accuracy assessments shows that reach width estimates should include a tolerance of between 48% (<50 m) and 15% (200–600 m) if used for buffer designation of permanent protection areas in environmental licensing.”

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Geographical Information Systems in Selection of States to Participate in a Long-term Transformative Programme to Build Leadership and Accountability in Nigeria’s Health Sector

Global Health Metrics & Evaluation: Controversies, Innovation, Accountability, 14–16 March 2011

Anddy Omoluabi, Osondu Ogbuoji, and Chioma Ogbozor

“Background: With competing interests and priorities by funding agencies and the need for quick wins, the selection of project states continues to be subjective in Nigeria. To address this issue, Management Sciences for Health (MSH) recently applied a geographical information system (GIS) to objectively and transparently select states for the implementation of a long-term transformative programme to build leadership and accountability in Nigeria’s health sector. The aim of our study was to provide an objective and transparent basis for the selection of two of 36 possible states and the Federal Capital Territory, and to communicate the outcome to relevant stakeholders.

“Methods: Relevant stakeholders including the project funder were consulted and agreed to demographic parameters including: high State HIV/AIDS prevalence, minimum presence of other donor-funded HIV/AIDS programmes, reasonable security alert levels, accessibility to other MSH offices, and presence of graduates of the MSH Fellowship Programme. With secondary demographic data, a one-to-many relationship was established between these attribute data and a state-level shapefile with the use of Manifold professional edition build 8.0.16. A layer of the state-level map was created for each parameter, and a series of select queries with agreed upon values were ran on the appropriate fields in the attribute data. The resultant maps were layered onto one and varying transparency levels were set to allow for visualisation across all the layers.

“Findings: The rationale, transparency, graphical results, and objectivity of the process facilitated the acceptance of and buy-in to the choice of the Federal Capital Territory and Gombe States by the donor agency and other stakeholders.

“Interpretation: GIS as a decision support system can help to objectively select states by managing and analysing multiple selection parameters and promote buy-in by relevant stakeholders.”

Haiti: Spatial Analysis of Vulnerability

17th Annual International Sustainable Development Research Conference (ISDRC 17), 8–10 May 2011

L. Razafindrazay, A. Morel, and S. Baptista

“The Caribbean Basin is among the most vulnerable regions to natural hazards and climate change (e.g., Manuel-Navarrete et al. 2007; Ibarrarán et al. 2009; Rossing & Rubin 2010). Haiti has the combined challenges of a severely degraded environment, extreme poverty, limited institutional and governance capacity, and repeated occurrence of natural hazards such as hurricanes, floods, landslides, and earthquakes(e.g., McAdoo & Paravisini-Gebert 2011). However, these challenges are not distributed evenly across the country. Key drivers of deforestation and land degradation in Haiti include the internal demand for charcoal and the cultivation of steep slopes (e.g., Murray 1987; Stevenson 1989). Interactions between socio-economic and natural hazard vulnerabilities need to be better understood spatially in order to support sustainable development efforts aimed at reducing poverty while managing multiple hazard-related risks.”