International Institute for Geo information Science and Earth Observation ITC

Enschede, Netherlands

International Institute for Geo information Science and Earth Observation ITC

Enschede, Netherlands
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Voinov A.,International Institute for Geo information Science and Earth Observation ITC | Cerco C.,U.S. Army
Environmental Modelling and Software | Year: 2010

Model integration is becoming increasingly important as our impacts on the environment become more severe and the systems we analyze become more complex. There are numerous attempts to make different models work in concert. However model integration usually treats models as software components only, ignoring the evolving nature of models and their constant modification and re-calibration to better represent reality. As a result, the changes that used to impact only contained models of subsystems, now propagate throughout the integrated system, across multiple model components. This makes it harder to keep the overall complexity under control and, in a way, defeats the purpose of modularity, where efficiency is supposed to be gained from independent development of modules. We argue that data that are available for module calibration can serve as an intermediate linkage tool, sitting between modules and providing a module-independent baseline, which is then adjusted when scenarios are to be run. In this case, it is not the model output that is directed into the next model. Rather, model output is presented as a variation around the baseline trajectory, and it is this variation that is then fed into the next module down the chain. The Chesapeake Bay Program suite of models is used to illustrate these problems and the possible remedy.

Wielstra B.,Netherlands Center for Biodiversity Naturalis | Wielstra B.,International Institute for Geo Information Science and Earth Observation ITC | Arntzen J.W.,International Institute for Geo Information Science and Earth Observation ITC
BMC Evolutionary Biology | Year: 2011

Background: The rapid radiation of crested newts (Triturus cristatus superspecies) comprises four morphotypes: 1) the T. karelinii group, 2) T. carnifex - T. macedonicus, 3) T. cristatus and 4) T. dobrogicus. These vary in body build and the number of rib-bearing pre-sacral vertebrae (NRBV). The phylogenetic relationships of the morphotypes have not yet been settled, despite several previous attempts, employing a variety of molecular markers. We here resolve the crested newt phylogeny by using complete mitochondrial genome sequences. Results: Bayesian inference based on the mitogenomic data yields a fully bifurcating, significantly supported tree, though Maximum Likelihood inference yields low support values. The internal branches connecting the morphotypes are short relative to the terminal branches. Seen from the root of Triturus (NRBV = 13), a basal dichotomy separates the T. karelinii group (NRBV = 13) from the remaining crested newts. The next split divides the latter assortment into T. carnifex - T. macedonicus (NRBV = 14) versus T. cristatus (NRBV = 15) and T. dobrogicus (NRBV = 16 or 17). Conclusions: We argue that the Bayesian full mitochondrial DNA phylogeny is superior to previous attempts aiming to recover the crested newt species tree. Furthermore, our new phylogeny involves a maximally parsimonious interpretation of NRBV evolution. Calibrating the phylogeny allows us to evaluate potential drivers for crested newt cladogenesis. The split between the T. karelinii group and the three other morphotypes, at ca. 10.4 Ma, is associated with the separation of the Balkan and Anatolian landmasses (12-9 Ma). No currently known vicariant events can be ascribed to the other two splits, first at ca. 9.3 Ma, separating T. carnifex - T. macedonicus, and second at ca. 8.8 Ma, splitting T. cristatus and T. dobrogicus. The crested newt morphotypes differ in the duration of their annual aquatic period. We speculate on the role that this ecological differentiation could have played during speciation. © 2011 Wielstra and Arntzen; licensee BioMed Central Ltd.

de Man W.H.E.,International Institute for Geo Information Science and Earth Observation ITC
Transactions in GIS | Year: 2013

Notwithstanding optimistic rhetoric about integrating geospatial data from different sources and supporting good governance, much of the literature on geoinformation management is limited to a technical orientation with a positivist paradigm. Complex geoinformation management, like public policy, must go beyond these boundaries. The article calls attention to the underexposed role of dilemmas in geoinformation management and how to cope with them. It uses lessons from the development of 'integrated surveys' at the former International Training Centre for Aerial Survey (ITC) in The Netherlands as an early and practical case of managing geoinformation for public policy some 40 years ago. These lessons are apparently also relevant to modern digital geoinformation management, as in SDI. Focus on public policy requires not only integration of geospatial data from different sources but also integration of geoinformation into complex decision-making processes. This complexity probably creates dilemmas because of mutually incompatible perspectives between different actors on what is to be managed. Geoinformation management for public policy therefore requires the ability to find, over and over again, a common ground between and beyond incompatible perspectives. The article proposes a 'transdisciplinary' framing of geoinformation management to support the required thinking outside the box. © 2013 John Wiley & Sons Ltd.

Georgiadou Y.,International Institute for Geo Information Science and Earth Observation ITC | Stoter J.,International Institute for Geo Information Science and Earth Observation ITC
Computers, Environment and Urban Systems | Year: 2010

The aim of this paper is to develop a conceptual framework for studying the use of geo-information and associated technology in government. We first review how geo-information, geo-information technology and people-notions central to geo-information use-are conceptualized in the literature and show that authors view these notions through two contrasting lenses, a market and a polis lens. We then present a people-centered conceptual framework for the study of geo-information use in government. The framework encompasses people's values, people's practices and the rules that people are expected to follow to optimize the use of geo-information. We show how the market and polis lenses illuminate the study of values, practices and rules in different ways resulting in radically different insights. Finally, we illustrate the usefulness of the conceptual framework with preliminary findings from a longitudinal empirical study in the Netherlands. © 2009 Elsevier Ltd. All rights reserved.

Perez Lapena B.,University of Twente | Wijnberg K.M.,University of Twente | Hulscher S.J.M.H.,University of Twente | Stein A.,International Institute for Geo Information Science and Earth Observation ITC
Journal of Applied Ecology | Year: 2010

1. Assessing and monitoring the impact of offshore wind farms on marine fauna is vital if we want to achieve ecologically sustainable development of this renewable energy resource. Given the complexity of the marine environment, a method capable of accommodating spatio-temporal behaviour of specific species and their interrelation with other marine phenomena is an essential prerequisite for investigating whether or not there has been any measurable impact to date.2. This paper presents a method based on geostatistical simulation to assess whether pre- and post-construction collected bird count data suggest displacement of birds due to the wind farm. The method takes into account spatial autocorrelation in species abundance at various scales, pre- and post-construction differences in environmental conditions and in survey effort and design.3. We demonstrate that taking these factors into account influences the conclusions about a wind farm's impact on bird life. In particular, incorporating spatial autocorrelation in seabird numbers is an important factor in reducing the risk of wrongly identifying an effect of a wind farm on bird abundance.4. Synthesis and applications. The development of offshore wind farms is often in conflict with nature conservation interests. Environmental impact assessment and monitoring is essential to protect and manage the marine environment. The method described here will allow scarce data to be utilized effectively as a basis for well-informed environmental decisions. In addition, the method will assist in the design of optimal monitoring procedures at a given site, balancing costs and effectiveness in detecting potentially harmful impacts. © 2010 The Authors. Journal compilation © 2010 British Ecological Society.

van der Gesest K.,AISSR | Vrieling A.,International Institute for Geo Information Science and Earth Observation ITC | Dietz T.,AISSR
Environment and Urbanization | Year: 2010

Migration-environment linkages are at the centre of media attention because of public concern about climate change and a perceived "flooding" of migrants from less developed countries into more affluent parts of the world. In the past few years, a substantial body of conceptual literature about environmentally induced migration has evolved, but there is still a paucity of empirical work in this area. Moreover, the environmental causes of migration have been studied largely in isolation of the environmental consequences. In this paper we present an analysis of migration and vegetation dynamics for one country (Ghana) to assess four migration-environment linkages. On the one hand, we look at two environmental drivers of migration: environmental push and pull. On the other hand, we look at the environmental impact of migration on source and destination areas. Census data at the district level (N=110) are used to map domestic migration flows in Ghana, which are then related to vegetation dynamics retrieved from a remotely sensed Normalized Difference Vegetation Index (NDVI) dataset (1981- 2006). The analysis shows that at the national level, there are significant but weak correlations between migration and vegetation cover and trends therein. Districts with a migration deficit (more out-migration than in-migration) tend to be more sparsely vegetated and have experienced a more positive NDVI trend over the past quarter century than districts with a migration surplus. A disaggregation of data in three principle migration systems shows stronger correlations. Namely that north-south migration and cocoa frontier settlement have important environmental dimensions, but environmental factors do not seem to play a major role in migration to the capital, Accra. An important insight from this paper is that migration flows in Ghana can be explained partly by vegetation dynamics but are also strongly related to rural population densities. This is because access to natural resources is often more important than the scarcity or abundance of natural resources per se. This study further shows that satellite remote sensing can provide valuable input to analyses of migration-environment linkages. © 2010 International Institute for Environment and Development (IIED).

Verstappen H.T.,International Institute for Geo Information Science and Earth Observation ITC
Geografia Fisica e Dinamica Quaternaria | Year: 2011

Natural hazards, threatening many parts of the world, are often ignored in the context of regional planning and environmental management, although this is necessary for avoiding, or at least substantially reducing the recurrence interval and magnitude of the related «natural» disasters. This is particularly the case for «creeping» disasters, related to environmental degradation caused by slow and in many cases almost imperceptible processes, including desertification, salinization, certain forms of soil erosion, pollution, etc. The more spectacular instantaneous disasters, resulting from high-intensity and low-frequency natural events of endogenous or exogenous origin, are nowadays reported about by the media world-wide. They are, however, soon out of focus again and adequate measures to prevent similar disasters in the future do not always remain a high priority of the responsible authorities. Disaster reduction through environmental management is a complex issue that requires interdisciplinary applied research related to the natural environment as well as to the socio-economic situation of the endangered societies. In fact, sustainability is at stake. For the implementation of adequate protection measures, ranging from «hard» engineering structures to «soft» management improvements, optimal cooperation between the various sectors of the communities concerned is essential. This multisectoral approach should lead up to a master-plan for long term regional management and a disaster scenario specifying tasks and responsibilities of organizations and individuals in case of an emergency situation. Apart from natural disasters, technical-industrial disasters and also the, often neglected, ecological disasters should be considered. Humanitarian disasters are, unfortunately, largely outside the field of science. The UNIDNDR (International Decade for Natural Disaster Reduction) program of the 19nineties concentrated on natural disasters only. Its follow-up, the UN-ISDR (International Strategy for Disaster Reduction), has a broader scope because technological / industrial disasters are also included. Examples are given of volcanic disasters in Indonesia, including gas emanations on the Dieng plateau and pyroclastic flows on the densely populated SW slopes of the Merapi volcano in Central Java, Further, the effects of the ill-famed eruption of the Nevado de Ruiz volcano, Colombia in 1985 are discussed in relation to shortcomings in disaster mitigation systems. Drought and desertification studies executed in northern Chad and in Botswana are discussed thereafter as an introduction to the problems of assessing and achieving global sustainability problems.

Nefeslioglu H.A.,General Directorate of Mineral Research and Exploration | Gokceoglu C.,Hacettepe University | Sonmez H.,Hacettepe University | Gorum T.,International Institute for Geo information Science and Earth Observation ITC
Landslides | Year: 2011

The main purpose of this study is to develop a new hazard evaluation technique considering the current limitations, particularly for shallow landslides. For this purpose, the Buyukkoy catchment area, located in the East Black Sea Region in the east of Rize province and the south of Cayeli district, was selected as the study area. The investigations were executed in four different stages. These were (1) preparation of a temporal shallow landslide inventory of the study area, (2) assessment of conditioning factors in the catchment, (3) susceptibility analyses and (4) hazard evaluations and mapping. A total of 251 shallow landslides in the period of 1955-2007 were recognised using different data sources. A 'Sampling Circle' approach was proposed to define shallow landslide initiation in the mapping units in susceptibility evaluations. To accomplish the susceptibility analyses, the method of artificial neural networks was implemented. According to the performance analyses conducted using the training and testing datasets, the prediction and generalisation capacities of the models were found to be very high. To transform the susceptibility values into hazard rates, a new approach with a new equation was developed, taking into account the behaviour of the responsible triggering factor over time in the study area. In the proposed equation, the threshold value of the triggering factor and the recurrence interval are the independent variables. This unique property of the suggested equation allows the execution of more flexible and more dynamic hazard assessments. Finally, using the proposed technique, shallow landslide initiation hazard maps of the Buyukkoy catchment area for the return periods of 1, 2, 5, 10, 50 and 100 years were produced. © 2011 Springer-Verlag.

Carranza E.J.M.,International Institute for Geo Information Science and Earth Observation ITC
Geochemistry: Exploration, Environment, Analysis | Year: 2010

In this study, continuous field models of geochemical landscapes were obtained by interpolating stream sediment geochemical data while discrete field models of geochemical landscapes were obtained by attributing stream sediment geochemical data to their sample catchment basins. This study aimed to: (1) compare and contrast anomaly maps derived from continuous and discrete field models of stream sediment geochemical landscapes; and (2) determine which empirical frequency distributions - those of original point data or those of pixels values in models of stream sediment geochemical landscapes - are more useful in mapping of anomalies in such geochemical landscapes. Anomalies were mapped by using the mean+2SDEV (standard deviation), median+2MAD (median absolute deviation) and concentration-area (C-A) fractal methods of identifying threshold values in a geochemical data set. The results of the study in the Aroroy gold district (Philippines) highlight the following findings. In mapping of anomalies in either continuous or discrete field models of stream sediment geochemical landscapes, the C-A fractal method performs best, followed by the median+2MAD method and then by the mean+2SDEV method. Anomalies mapped in discrete field models, compared to anomalies mapped in continuous field models, of stream sediment geochemical landscapes mostly have stronger positive spatial associations with the known epithermal Au deposit occurrences in the study area. Empirical frequency distributions of either the original point data or the pixels values in the models of stream sediment geochemical landscapes are similarly useful in applying the C-A fractal method, but not in applying either the median+2MAD or mean+2SDEV method, to map anomalies in either continuous or discrete field models of such geochemical landscapes. © 2010 AAG/Geological Society of London.

Carranza E.J.M.,International Institute for Geo Information Science and Earth Observation ITC
Geochemistry: Exploration, Environment, Analysis | Year: 2010

This paper revisits catchment basin modelling of stream sediment geochemical anomalies with regard to two aspects: (1) standardization of uni-element residuals derived from analysis of a number of subsets of stream sediment geochemical data in order to obtain a single set of uni-element residuals for classification of anomalies; and (2) objective classification of anomalies in dilution-corrected uni-element residuals and in derivative scores representing multi-element associations. These two aspects of catchment basin modelling of stream sediment geochemical anomalies were examined in the Aroroy epithermal-Au district (Philippines). For the first aspect, the results of the case study show that, for the standardization of dilution-corrected uni-element residuals per data subset in order to derive a single set of dilution-corrected uni-element residuals for classification of anomalies, the application of robust statistics in exploratory data analysis is preferable to the application of classical statistics in confirmatory data analysis. For the second aspect, the results of the case study show that anomalies in standardized dilution-corrected uni-element residuals and in derivative scores representing multi-element associations can be identified objectively by application of the concentration-area fractal analysis. The results of the case study further show that the area of individual sample catchment basins is useful in GIS-based screening of significant anomalies by integrating derivative geochemical variables with fault/ fracture density, which was estimated as the ratio of number of pixels representing faults/fractures in a sample catchment basin to number of pixels in the same sample catchment basin. © 2010 Geological Society of London.

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