Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Mapping European canker spatial pattern and disease progression in apples using GIS, Tasman, New Zealand
Iorio, Diletta Di ; Walter, Monika ; Lantinga, Egbert ; Kerckhoffs, Huub ; Campbell, Rebecca E. - \ 2019
New Zealand Plant Protection 72 (2019). - ISSN 1175-9003 - p. 176 - 184.
Apple - Disease progression - European canker - Geographical Information Systems - GIS - Hot-spots - Neonectria ditissima - Spatial - Temporal

European canker (EC), caused by Neonectria ditissima, is an important disease in apple-producing regions in New Zealand. In order to improve plant protection, Geographic Information Systems (GIS) can be used to map plant disease location and severity in agricultural settings. Data were compiled from apple growers in Tasman, New Zealand, to investigate EC distribution over 4 years, for the period 2015–2018. ArcGIS software, including the Spatial Analyst, Interpolation and Geospatial statistics toolboxes, was used to map EC incidence at the spatial scale of orchard blocks, which allowed the identification of disease hot-spots. A clustered spatial pattern of disease was detected every year and areas with higher risk of EC were identified within the region. The spatial patterns detected were related to disease pressure over time for different apple cultivars. The use of GIS provides a platform for analysing and visually communicating disease patterns over time. Investigating disease spatial pattern allows the inference of spatial processes and further hypothesis generation to understand the pathogen.

Uncertainties of prediction accuracy in shallow landslide modeling : Sample size and raster resolution
Shirzadi, Ataollah ; Solaimani, Karim ; Roshan, Mahmood Habibnejad ; Kavian, Ataollah ; Chapi, Kamran ; Shahabi, Himan ; Keesstra, Saskia ; Ahmad, Baharin Bin ; Bui, Dieu Tien - \ 2019
Catena 178 (2019). - ISSN 0341-8162 - p. 172 - 188.
Alternating decision tree - GIS - Landslide susceptibility - Pixel and sample size - Uncertainty

Understanding landslide characteristics such as their locations, dimensions, and spatial distribution is of highly importance in landslide modeling and prediction. The main objective of this study was to assess the effect of different sample sizes and raster resolutions in landslide susceptibility modeling and prediction accuracy of shallow landslides. In this regard, the Bijar region of the Kurdistan province (Iran) was selected as a case study. Accordingly, a total of 20 landslide conditioning factors were considered with six different raster resolutions (10 m, 15 m, 20 m, 30 m, 50 m, and 100 m) and four different sample sizes (60/40%, 70/30%, 80/20%, and 90/10%) were investigated. The merit of each conditioning factors was assessed using the Information Gain Ratio (IGR) technique, whereas Alternating decision tree (ADTree), which has been rarely explored for landslide modeling, was used for building models. Performance of the models was assessed using the area under the ROC curve (AUROC), sensitivity, specificity, accuracy, kappa and RMSE criteria. The results show that with increasing the number of training pixels in the modeling process, the accuracy is increased. Findings also indicate that for the sample sizes of 60/40% (AUROC = 0.800) and 70/30% (AUROC = 0.899), the highest prediction accuracy is derived with the raster resolution of 10 m. With the raster resolution of 20 m, the highest prediction accuracy for the sample size of 80/20% (AUROC = 0.871) and 90/10% (AUROC = 0.864). These outcomes provide a guideline for future research enabling researchers to select an optimal data resolution for landslide hazard modeling.

Participatory ecosystem service mapping to enhance community-based mangrove rehabilitation and management in Demak, Indonesia
Damastuti, Ekaningrum ; Groot, Rudolf de - \ 2019
Regional Environmental Change 19 (2019)1. - ISSN 1436-3798 - p. 65 - 78.
Community-based mangrove management - Demak - Ecosystem services - Environmental change - GIS - Participatory resource mapping

Assessment of mangrove ecosystem services (ES) is essential to understand and manage the contribution of these ecosystems to the well-being of local communities. They are the primary beneficiaries but their experience, knowledge, and information are frequently ignored in ES assessment and mapping. In this study, a participatory resource mapping (PRM) approach was applied using local knowledge and experience to analyze geo-referenced information on mangrove ecosystem services. Local communities were involved from the beginning in method selection, application, evaluation, and verification. This “inclusive participatory ES mapping” was conducted in two villages (Bedono and Timbulsloko, Central Java, Indonesia) from 2014 to 2015. Participants representing different community elements were involved in the mapping process. They first created a historical map of the situation in their villages roughly between 1980 and 1999 (before rehabilitation) and then described the subsequent environmental changes. The mapping exercise also documented different mangrove resources that are utilized by communities and identified key areas, such as harvesting zones, biodiversity hotspots, erosion zones, different fishing grounds, and newly rehabilitated areas. The maps reveal that integrating PRM and indigenous geo-referenced information can elicit past and contemporary information on (changes in) ecosystem service availability and use. The results show that by involving local communities from the beginning, the participatory ES mapping can facilitate social learning, provide the foundation for the creation of social capital, and equip the community with sufficient spatial information to improve local mangrove management. The participatory ES mapping approach presented in this paper can be used as a model to support local and regional decision-making processes and to enhance community-based mangrove management in other coastal regions in Indonesia and beyond.

Effects of urbanization on river morphology of the Talar River, Mazandarn Province, Iran
Yousefi, Saleh ; Moradi, Hamid Reza ; Keesstra, Saskia ; Pourghasemi, Hamid Reza ; Navratil, Oldrich ; Hooke, Janet - \ 2019
Geocarto International 34 (2019)3. - ISSN 1010-6049 - p. 276 - 292.
GIS - land cover - river channel change - River morphology
In the present study, we investigate the effects of urbanization growth on river morphology in the downstream part of Talar River, east of Mazandaran Province, Iran. Morphological and morphometric parameters in 10 equal sub-reaches were defined along a 11.5 km reach of the Talar River after land cover maps were produced for 1955, 1968, 1994, 2005 and 2013. Land cover types changed extremely during the study period. Residential lands were found to have increased in area by about 1631%, while forest land and riparian vegetation decreased in by approximately 99.9 and 96.2%, respectively. The results of morphometric and morphological factors showed that average channel width (W) for all 11.5 km of the study river decreased by 84% during the study period, while the flow length increased by about 2.14%.
Quality of terrestrial data derived from UAV photogrammetry : A case study of Hetao irrigation district in northern China
Zhang, Hongming ; Yang, Jiang Tao ; Baartman, Jantiene E.M. ; Li, Shu Qin ; Jin, Bei ; Han, Wen Ting ; Yang, Xiaomei ; Gai, Lingtong ; Ritsema, Coen J. ; Geissen, Violette - \ 2018
International Journal of Agricultural and Biological Engineering 11 (2018)3. - ISSN 1934-6344 - p. 171 - 177.
Accuracy evaluation - DEM - GIS - Irrigation area - Photogrammetry - UAVs

Most crops in northern China are irrigated, but the topography affects the water use, soil erosion, runoff and yields. Technologies for collecting high-resolution topographic data are essential for adequately assessing these effects. Ground surveys and techniques of light detection and ranging have good accuracy, but data acquisition can be time-consuming and expensive for large catchments. Recent rapid technological development has provided new, flexible, high-resolution methods for collecting topographic data, such as photogrammetry using unmanned aerial vehicles (UAVs). The accuracy of UAV photogrammetry for generating high-resolution Digital Elevation Model (DEM) and for determining the width of irrigation channels, however, has not been assessed. A fixed-wing UAV was used for collecting high-resolution (0.15 m) topographic data for the Hetao irrigation district, the third largest irrigation district in China. 112 ground checkpoints (GCPs) were surveyed by using a real-time kinematic global positioning system to evaluate the accuracy of the DEMs and channel widths. A comparison of manually measured channel widths with the widths derived from the DEMs indicated that the DEM-derived widths had vertical and horizontal root mean square errors of 13.0 and 7.9 cm, respectively. UAV photogrammetric data can thus be used for land surveying, digital mapping, calculating channel capacity, monitoring crops, and predicting yields, with the advantages of economy, speed and ease.

A GIS-based approach for identifying potential sites for harvesting rainwater in the Western Desert of Iraq
Adham, Ammar ; Sayl, Khamis Naba ; Abed, Rasha ; Abdeladhim, Mohamed Arbi ; Wesseling, Jan G. ; Riksen, Michel ; Fleskens, Luuk ; Karim, Usama ; Ritsema, Coen J. - \ 2018
International Soil and Water Conservation Research 6 (2018)4. - ISSN 2095-6339 - p. 297 - 304.
GIS - Iraq's western desert - Rainwater harvesting - Suitability map

People living in arid and semi-arid areas with highly variable rainfall and unforeseeable periods of droughts or floods are severely affected by water shortages and often have insecure livelihoods. The construction of dams in wadies to harvest rainwater from small watersheds and to induce artificial groundwater recharge is one of the solutions available to overcome water shortages in the Western Desert of Iraq. The success of rainwater harvesting (RWH) systems depends heavily on their technical design and on the identification of suitable sites. Our main goal was to identify suitable sites for dams using a suitability model created with ModelBuilder in ArcGIS 10.2. The model combined various biophysical factors: slope, runoff depth, land use, soil texture, and stream order. The suitability map should be useful to hydrologists, decision-makers, and planners for quickly identifying areas with the highest potential for harvesting rainwater. The implementation of this method should also support any policy shifts towards the widespread adoption of RWH.

Integrating local knowledge and remote sensing for eco-type classification map in the Barotse Floodplain, Zambia
Rio, Trinidad Del; Groot, Jeroen C.J. ; DeClerck, Fabrice ; Estrada-Carmona, Natalia - \ 2018
Data in Brief 19 (2018). - ISSN 2352-3409 - p. 2297 - 2304.
Barotseland - Geographical distribution - GIS - Landsat-8 satellite data - Thematic map - Vegetation types

This eco-type map presents land units with distinct vegetation and exposure to floods (or droughts) in three villages in the Barotseland, Zambia. The knowledge and eco-types descriptions were collected from participatory mapping and focus group discussions with 77 participants from Mapungu, Lealui, and Nalitoya. We used two Landsat 8 Enhanced Thematic Mapper (TM) images taken in March 24th and July 14th, 2014 (path 175, row 71) to calculate water level and vegetation type which are the two main criteria used by Lozi People for differentiating eco-types. We calculated water levels by using the Water Index (WI) and vegetation type by using the Normalized Difference Vegetation Index (NDVI). We also calculated the Normalized Burn Ratio (NBR) index. We excluded burned areas in 2014 and built areas to reduce classification error. Control points include field data from 99 farmers’ fields, 91 plots of 100 m2 and 65 waypoints randomly selected in a 6 km radius around each village. We also used Google Earth Pro to create control points in areas flooded year-round (e.g., deep waters and large canals), patches of forest and built areas. The eco-type map has a classification accuracy of 81% and a pixel resolution of 30 m. The eco-type map provides a useful resource for agriculture and conservation planning at the landscape level in the Barotse Floodplain.

Mapping abiotic stresses for rice in Africa : Drought, cold, iron toxicity, salinity and sodicity
Oort, P.A.J. van - \ 2018
Field Crops Research 219 (2018). - ISSN 0378-4290 - p. 55 - 75.
Crop maps - GIS - HWSD - ORYZA2000 - Uncertainty
Maps of abiotic stresses for rice can be useful for (1) prioritizing research and (2) identifying stress hotspots, for directing technologies and varieties to those areas where they are most needed. Large-scale maps of stresses are not available for Africa. This paper considers four abiotic stresses relevant for rice in Africa (drought, cold, iron toxicity and salinity/sodicity). Maps showing hotspots of the stresses, the countries most affected and total potentially affected area are presented. In terms of relative importance, the study identified drought as the most important stress (33% of rice area potentially affected), followed by iron toxicity (12%) and then cold (7%) and salinity/sodicity (2%). Hotspots for iron toxicity, cold and salinity are identified. For drought, local variation along the hydromorphic zone was a stronger determinant than larger-scale climatic variation, therefore mapping of drought based on climatic zones has only limited value. Uncertainties in the mappings are discussed.
The peatland map of Europe
Tanneberger, Franziska ; Tegetmeyer, C. ; Busse, S. ; Barthelmes, A. ; Shumka, S. ; Mariné, A.M. ; Jenderedjian, K. ; Steiner, G.M. ; Essl, F. ; Etzold, J. ; Mendes, C. ; Kozulin, A. ; Frankard, P. ; Milanović, ; Ganeva, A. ; Apostolova, I. ; Alegro, A. ; Delipetrou, P. ; Navrátilová, J. ; Risager, M. ; Leivits, A. ; Fosaa, A.M. ; Tuominen, S. ; Muller, F. ; Bakuradze, T. ; Sommer, M. ; Christanis, K. ; Szurdoki, E. ; Oskarsson, H. ; Brink, S.H. ; Connolly, J. ; Bragazza, L. ; Martinelli, G. ; Aleksāns, O. ; Priede, A. ; Sungaila, D. ; Melovski, L. ; Belous, T. ; Saveljić, D. ; Vries, F. De; Moen, A. ; Dembek, W. ; Mateus, J. ; Hanganu, J. ; Sirin, A. ; Markina, A. ; Napreenko, M. ; Lazarević, P. ; Stanová, V.Š. ; Skoberne, P. ; Pérez, P.H. ; Pontevedra-Pombal, X. ; Lonnstad, J. ; Küchler, M. ; Wüst-Galley, C. ; Kirca, S. ; Mykytiuk, O. ; Lindsay, R. ; Joosten, H. - \ 2017
Mires and Peat 19 (2017). - ISSN 1819-754X
Drained peatland - GIS - Histosol - Mire - Organic soil - Peat
Based on the ‘European Mires Book’ of the International Mire Conservation Group (IMCG), this article provides a composite map of national datasets as the first comprehensive peatland map for the whole of Europe. We also present estimates of the extent of peatlands and mires in each European country individually and for the entire continent. A minimum peat thickness criterion has not been strictly applied, to allow for (often historically determined) country-specific definitions. Our ‘peatland’ concept includes all ‘mires’, which are peatlands where peat is being formed. The map was constructed by merging national datasets in GIS while maintaining the mapping scales of the original input data. This ‘bottom-up’ approach indicates that the overall area of peatland in Europe is 593,727 km2. Mires were found to cover more than 320,000 km2 (around 54 % of the total peatland area). If shallow-peat lands (< 30 cm peat) in European Russia are also taken into account, the total peatland area in Europe is more than 1,000,000 km2 which is almost 10 % of the total surface area. Composite inventories of national peatland information, as presented here for Europe, may serve to identify gaps and priority areas for field survey, and help to cross-check and calibrate remote sensing based mapping approaches.
Natura 2000 and spatial planning
Grift-Simeonova, V.S. van der; Bouwma, I.M. ; Grift, E.A. van der; Sunyer, Carlos ; Manteiga, Lola ; Külvik, Mart ; Suškevičs, Monika ; Dimitrov, S. ; Dimitrova, Ana - \ 2017
Brussel : DG Environment, European Commission - 124 p.
Natura 2000 - spatial planning - EU legislation - GIS - cross-border cooperation
Spatial planning which reconciles nature conservation with other policies' objectives can be a useful tool for implementing the EU nature legislation. However, a thorough exploration of the potential role of spatial planning and its instruments for the implementation of Natura 2000 has not yet been made either at EU or Member State level. In order to bridge this knowledge gap, this study provides an insight into the role and functions of spatial planning policies at EU and Member State level in relation to Natura 2000 and Nature Directives more generally. The key areas of analysis in this study are the notion and rationale of spatial planning, its instruments and governance processes, the mechanisms for integration of Natura 2000 in spatial planning processes and in sectoral policies, the EU-legal frameworks, cross border-cooperation and relevant spatial planning technologies.
Mapping land-use dynamic in the Vietnamese mekong delta
Le, Thuy Ngan ; Bregt, Arnold K. - \ 2017
In: SGEM2017 Conference Proceedings SGEM (International Multidisciplinary Scientific GeoConference &amp; EXPO SGEM 23) - ISBN 9786197408034 - p. 589 - 594.
GIS - Land-use - Mekong Delta - Time-series map - Vietnam

Policies supporting rice cultivation and investments in water infrastructures facilitated intensification and diversification of land-use in the Vietnamese Mekong Delta. Although the major changes are acknowledged in the literature, few studies have examined the dynamism of land-use across the delta. Overlaying land-use maps, we identified land-use dynamic by the number of changes observed during the 11-year study period. Land-use was found to be highly variable, changing by 14.94% annually between 2001 and 2012. Rice cropping underwent the greatest change, evolving from single cropping of traditional varieties towards double and triple cropping of highyielding varieties. A clear trend was observable in the upper delta, where large expanses of triple rice cropping, especially within the dyke systems. Changes in land-use were also observed in the central delta and coastal zone, but here the pattern was more fragmented. Meanwhile, aquaculture remained stable after rapid expansion in the early 2000s.

An improved method for calculating slope length (λ) and the LS parameters of the Revised Universal Soil Loss Equation for large watersheds
Zhang, Hongming ; Wei, Jicheng ; Yang, Qinke ; Baartman, Jantiene E.M. ; Gai, Lingtong ; Yang, Xiaomei ; Li, Shu Qin ; Yu, Jiantao ; Ritsema, Coen J. ; Geissen, Violette - \ 2017
Geoderma 308 (2017). - ISSN 0016-7061 - p. 36 - 45.
GIS - LS - RUSLE - Soil erosion - Terrain analysis
The Universal Soil Loss Equation (USLE) and its revised version (RUSLE) are often used to estimate soil erosion at regional landscape scales. USLE/RUSLE contain parameters for slope length factor (L) and slope steepness factor (S), usually combined as LS. However a major limitation is the difficulty in extracting the LS factor. Methods to estimate LS based on geographic information systems have been developed in the last two decades. L can be calculated for large watersheds using the unit contributing area (UCA) or the slope length (λ) as input parameters. Due to the absence of an estimation of slope length, the UCA method is insufficiently accurate. Improvement of the spatial accuracy of slope length and LS factor is still necessary for estimating soil erosion. The purpose of this study was to develop an improved method to estimate the slope length and LS factor. We combined the algorithm for multiple-flow direction (MFD) used in the UCA method with the LS-TOOL (LS-TOOLSFD) algorithms, taking into account the calculation errors and cutoff conditions for distance, to obtain slope length (λ) and the LS factor. The new method, LS-TOOLMFD, was applied and validated in a catchment with complexly variable slopes. The slope length and LS calculated by LS-TOOLMFD both agreed better with field data than with the calculations using the LS-TOOLSFD and UCA methods, respectively. We then integrated the LS-TOOLMFD algorithm into LS-TOOL developed in Microsoft's.NET environment using C# with a user-friendly interface. The method can automatically calculate slope length, slope steepness, L, S, and LS factor, providing the results as ASCII files that can be easily used in GIS software and erosion models. This study is an important step forward in conducting accurate large-scale erosion evaluation.
A territorial approach to assess the transition to trellis vineyards in special protection areas for steppe birds in Spain
Montero García, F. ; Brasa Ramos, A. ; Montero Riquelme, F. ; Carsjens, G.J. - \ 2017
Land Use Policy 67 (2017). - ISSN 0264-8377 - p. 27 - 37.
GIS - Grapevine - Great bustard - Habitat fragmentation - Vineyard structure

Traditional vineyards in Spain are being upgraded to trellis vineyards. A key question is to what extent the transition to trellis vineyards is compatible with the environmental preservation goals in Special Protection Areas. This paper presents a GIS-based model to assess the suitability of Special Protection Areas for the development of trellis systems. The model was applied in a Special Protection Area for steppe birds in Castilla-La Mancha, Spain, a region with the largest concentration of vineyards in the world. The model includes three components: (1) a vineyard structure analysis, (2) an analysis of habitat fragmentation, and (3) a suitability analysis. The results showed that 50.9% of the study area, including 82.1% of the existing vineyards, was classified as suitable for transition to trellis systems. In the remaining unsuitable areas an increase in trellis systems should be avoided. The model is a stepping stone for improving the sustainable land use development of Mediterranean agricultural landscapes. Further research is needed to include wider socio-economic and environmental consequences of modernizing viticulture practices.

AgriSuit : A web-based GIS-MCDA framework for agricultural land suitability assessment
Yalew, S.G. ; Griensven, A. van; Zaag, P. van der - \ 2016
Computers and Electronics in Agriculture 128 (2016). - ISSN 0168-1699 - p. 1 - 8.
AHP - GIS - Land suitability - Multi-criteria analysis - Remote sensing

A web-based framework (AgriSuit) that integrates various global data from different sources for multi-criteria based agricultural land suitability assessment based on the Google Earth Engine (GEE) platform is developed and presented. The platform enables online data gathering, training and classifying of land cover classes based on remote sensing and GIS techniques, as well as computation of suitability of land-use classes for agricultural activities. A demonstration of the framework on the Upper Blue Nile basin in Ethiopia is presented.

A methodology to assess and evaluate rainwater harvesting techniques in (semi-) arid regions
Adham, Ammar ; Riksen, Michel ; Ouessar, Mohamed ; Ritsema, Coen J. - \ 2016
Water 8 (2016)5. - ISSN 2073-4441
AHP approach - GIS - Jessour - RWH suitability - Tabias - Tunisia

Arid and semi-arid regions around the world face water scarcity problems due to lack of precipitation and unpredictable rainfall patterns. For thousands of years, rainwater harvesting (RWH) techniques have been applied to cope with water scarcity. Researchers have used many different methodologies for determining suitable sites and techniques for RWH. However, limited attention has been given to the evaluation of RWH structure performance. The aim of this research was to design a scientifically-based, generally applicable methodology to better evaluate the performance of existing RWH techniques in (semi-) arid regions. The methodology integrates engineering, biophysical and socio-economic criteria using the Analytical Hierarchy Process (AHP) supported by the Geographic Information System (GIS). Jessour/Tabias are the most traditional RWH techniques in the Oum Zessar watershed in south-eastern Tunisia, which were used to test this evaluation tool. Fifty-eight RWH locations (14 jessr and 44 tabia) in three main sub-catchments of the watershed were assessed and evaluated. Based on the criteria selected, more than 95% of the assessed sites received low or moderate suitability scores, with only two sites receiving high suitability scores. This integrated methodology, which is highly flexible, saves time and costs, is easy to adapt to different regions and can support designers and decision makers aiming to improve the performance of existing and new RWH sites.

A new approach to nationwide sanitation planning for developing countries : Case study of Indonesia
Kerstens, S.M. ; Spiller, M. ; Leusbrock, I. ; Zeeman, G. - \ 2016
Science of the Total Environment 550 (2016). - ISSN 0048-9697 - p. 676 - 689.
GIS - Investment and operational costs - Nationwide planning - Solid waste - Wastewater

Many developing countries struggle to provide wastewater and solid waste services. The backlog in access has been partly attributed to the absence of a functional sanitation planning framework. Various planning tools are available; however a comprehensive framework that directly links a government policy to nationwide planning is missing. Therefore, we propose a framework to facilitate the nationwide planning process for the implementation of wastewater and solid waste services. The framework requires inputs from government planners and experts in the formulation of starting points and targets. Based on a limited number of indicators (population density, urban functions) three outputs are generated. The first output is a visualization of the spatial distribution of wastewater and solid waste systems to support regional priority setting in planning and create awareness. Secondly, the total number of people served, budget requirements and distribution of systems is determined. Thirdly, the required budget is allocated to the responsible institution to assure effective implementation. The determined budgets are specified by their beneficiaries, distinguishing urban, rural, poor and non-poor households. The framework was applied for Indonesia and outputs were adopted in the National Development Plan. The required budget to reach the Indonesian government's 2019 target was determined to be 25 billion US$ over 5 years. The contribution from the national budget required a more than fivefold increase compared to the current budget allocation in Indonesia, corresponding to an increase from 0.5 to 2.7 billion US$ per year. The budget for campaigning, advocacy and institutional strengthening to enable implementation was determined to be 10% of the total budget. The proposed framework is not only suitable for Indonesia, but could also be applied to any developing country that aims to increase access to wastewater and solid waste facilities.

Spatiotemporal patterns of tropical deforestation and forest degradation in response to the operation of the Tucuruí hydroelectricdam in the Amazon basin
Chen, Gang ; Powers, Ryan P. ; Carvalho, Luis M.T. de; Mora, Brice - \ 2015
Applied Geography 63 (2015). - ISSN 0143-6228 - p. 1 - 8.
Amazon basin - Deforestation - Forest degradation - GIS - Hydroelectric dam - Remote sensing - Spatiotemporal pattern - Statistical analysis

The planned construction of hundreds of hydroelectric dams in the Amazon basin has the potential to provide invaluable 'clean' energy resources for aiding in securing future regional energy needs and continued economic growth. These mega-structures, however, directly and indirectly interfere with natural ecosystem dynamics, and can cause noticeable tree loss. To improve our understanding of how hydroelectric dams affect the surrounding spatiotemporal patterns of forest disturbances, this case study integrated remote sensing spectral mixture analysis, GIS proximity analysis and statistical hypothesis testing to extract and evaluate spatially-explicit patterns of deforestation (clearing of entire forest patch) and forest degradation (reduced tree density) in the 80,000km2 neighborhoods of the Brazil's Tucuruí Dam, the first large-scale hydroelectric project in the Amazon region, over a period of 25 years from 1988 to 2013. Results show that the average rates of deforestation were consistent during the first three time periods 1988-1995 (620km2 per year), 1995-2001 (591km2 per year), and 2001-2008 (660km2 per year). However, such rate dramatically fell to half of historical levels after 2008, possibly reflecting the 2008 global economic crisis and enforcement of the Brazilian Law of Environmental Crimes. The rate of forest degradation was relatively stable from 1988 to 2013 and, on average, was 17.8% of the rate of deforestation. Deforestation and forest degradation were found to follow similar spatial patterns across the dam neighborhoods, upstream reaches or downstream reaches at the distances of 5km-80km, suggesting that small and large-scale forest disturbances may have been influencing each other in the vicinity of the dam. We further found that the neighborhoods of the Tucuruí Dam and the upstream region experienced similar degrees of canopy loss. Such loss was mainly attributed to the fast expansion of the Tucuruí town, and the intensive logging activities alongside major roads in the upstream reservoir region. In contrast, a significantly lower level of forest disturbance was discovered in the downstream region.

A simple DEM assessment procedure for gully system analysis in the Lake Manyara area, northern Tanzania
Maerker, Michael ; Quénéhervé, Geraldine ; Bachofer, Felix ; Mori, Simone - \ 2015
Natural Hazards 79 (2015)suppl.1. - ISSN 0921-030X - p. 235 - 253.
DEM interpolation - GIS - Gully erosion - Soil erosion - Tanzania - Terrain analysis

Gully erosion is a major threat concerning landscape degradation in large areas along the northern Tanzanian Rift valley. It is the dominant erosion process producing large parts of the sediments that are effectively conducted into the river network. The study area is located in the Lake Manyara—Makuyuni River catchment, Arusha, northern Tanzania. During fieldwork, we measured topographic data of eight gully systems close to Makuyuni Town. The main focus of this study is to assess gully erosion dynamics using improved DEMs with original resolutions of 30 and 20 m, respectively. We assessed terrain characteristics to extract information on environmental drivers. To improve the DEM, we integrated information deduced from satellite images as well as from acquired GPS field data. Topographic indices such as Stream Power Index or Transport Capacity Index were derived from the re-interpolated DEM. To evaluate gully evolution, we assessed also the longitudinal slope profiles. Finally, the gully evolution phases of each gully were classified according to the concept proposed by Kosov et al. (Eksperimental’naya geomorfologiya, vol 3. Moscow University, Moskva, pp 113–140, 1978). The re-interpolated DEMs revealed a positive response especially for the more developed gullies. We show that the extraction of information on this spatial process scale based on “low-resolution” data is feasible with little additional fieldwork and image interpretation. In fact, areas identified as having a greater risk of gully erosion have been confirmed by observations and surveys carried out in the field.

Comparative analysis of soil erosion sensitivity using various quantizations within GIS environment : an application on Sperchios river basin in Central Greece
Paparrizos, Spyridon ; Maris, Fotios ; Kitikidou, Kyriaki ; Anastasiou, Theofilos ; Potouridis, Simeon - \ 2015
International Journal of River Basin Management 13 (2015)4. - ISSN 1571-5124 - p. 475 - 486.
contours - Erosion - Gavrilovič - GIS - Greece - quantization - RUSLE

Soil erosion is a prominent cause of land degradation and desertification in Mediterranean countries. The detrimental effects of soil erosion are exemplified in climate (in particular climate change), topography, human activities and natural disasters. Modelling of erosion and deposition in complex terrains within a geographic information system (GIS) requires reliable estimation of topographic factors, as well as the formulation of erosion models adequate for digital representation of spatially distributed parameters. In the current paper, two different approaches for the estimation of erosion in the Sperchios river basin are described and evaluated using GIS – the Revised Universal Soil Loss Equation and the Gavrilovič method. Implementing the ArcGIS 10.2.1 programme, the necessary input data for these approaches were estimated using four different quantizations that were created using topographic maps, courtesy of the Greek Geographical Army Service. The results indicated that even though a high-resolution quantization is always preferred for more reliable results, when there is a lack of available data, coarser quantizations can also be used to extract similar estimations.

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