Application of Landsat-8 and ALOS-2 data for structural and landslide hazard mapping in Kelantan, Malaysia

Identification of high potential risk and susceptible zones for natural hazards of geological origin is one of the most important applications of advanced remote sensing technology. Yearly, several landslides occur during heavy monsoon rainfall in Kelantan River basin, Peninsular Malaysia. Flooding and subsequent landslide occurrences generated significant damage to livestock, agricultural produce, homes and businesses in the Kelantan River basin. In this study, remote sensing data from the recently launched Landsat-8 and Phased Array type L-band Synthetic Aperture Radar-2 (PALSAR-2) on board the Advanced Land Observing Satellite-2 (ALOS-2) were used to map geologic structural and topographical features in the Kelantan River basin for identification of high potential risk and susceptible zones for landslides and flooding areas. The data were processed for a comprehensive analysis of major geological structures and detailed characterizations of lineaments, drainage patterns and lithology at both regional and district scales. The analytical hierarchy process (AHP) approach was used for landslide susceptibility mapping. Several factors such as slope, aspect, soil, lithology, normalized difference vegetation index (NDVI), land cover, distance to drainage, precipitation, distance to fault and distance to the road were extracted from remote sensing satellite data and fieldwork to apply the AHP approach. Directional convolution filters were applied to ALOS-2 data for identifying linear features in particular directions and edge enhancement in the spatial domain. Results indicate that lineament occurrence at regional scale was mainly linked to the N-S trending of the Bentong-Raub Suture Zone (BRSZ) in the west and Lebir Fault Zone in the east of the Kelantan state. The combination of different polarization channels produced image maps that contain important information related to water bodies, wetlands and lithological units. The N-S, NE-SW and NNE-SSW lineament trends and dendritic, sub-dendritic and rectangular drainage patterns were detected in the Kelantan River basin. The analysis of field investigation data indicates that many of flooded areas were associated with high potential risk zones for hydrogeological hazards such as wetlands, urban areas, floodplain scroll, meander bend, dendritic and sub-dendritic drainage patterns, which are located in flat topographic regions. Numerous landslide points were located in a rectangular drainage system that is associated with a topographic slope of metamorphic and quaternary rock units. Consequently, structural and topographical geology maps were produced for Kelantan River basin using PALSAR-2 data, which could be broadly applicable for landslide hazard mapping and identification of high potential risk zone for hydrogeological hazards. Geohazard mitigation programs could be conducted in the landslide recurrence regions and flooded areas to reduce natural catastrophes leading to loss of life and financial investments in the Kelantan River basin. In this investigation, Landsat-8 and ALOS-2 have proven to successfully provide advanced Earth observation satellite data for disaster monitoring in tropical environments

Landslide susceptibility mapping using remote sensing data and geographic information system-based algorithms

Whether they occur due to natural triggers or human activities, landslides lead to loss of life and damages to properties which impact infrastructures, road networks and buildings. Landslide Susceptibility Map (LSM) provides the policy and decision makers with some valuable information. This study aims to detect landslide locations by using Sentinel-1 data, the only freely available online Radar imagery, and to map areas prone to landslide using a novel algorithm of AB-ADTree in Cameron Highlands, Pahang, Malaysia. A total of 152 landslide locations were detected by using integration of Interferometry Synthetic Aperture RADAR (InSAR) technique, Google Earth (GE) images and extensive field survey. However, 80% of the data were employed for training the machine learning algorithms and the remaining 20% for validation purposes. Seventeen triggering and conditioning factors, namely slope, aspect, elevation, distance to road, distance to river, proximity to fault, road density, river density, Normalized Difference Vegetation Index (NDVI), rainfall, land cover, lithology, soil types, curvature, profile curvature, Stream Power Index (SPI) and Topographic Wetness Index (TWI), were extracted from satellite imageries, digital elevation model (DEM), geological and soil maps. These factors were utilized to generate landslide susceptibility maps using Logistic Regression (LR) model, Logistic Model Tree (LMT), Random Forest (RF), Alternating Decision Tree (ADTree), Adaptive Boosting (AdaBoost) and a novel hybrid model from ADTree and AdaBoost models, namely AB-ADTree model. The validation was based on area under the ROC curve (AUC) and statistical measurements of Positive Predictive Value (PPV), Negative Predictive Value (NPV), sensitivity, specificity, accuracy and Root Mean Square Error (RMSE). The results showed that AUC was 90%, 92%, 88%, 59%, 96% and 94% for LR, LMT, RF, ADTree, AdaBoost and AB-ADTree algorithms, respectively. Non-parametric evaluations of the Friedman and Wilcoxon were also applied to assess the models’ performance: the findings revealed that ADTree is inferior to the other models used in this study. Using a handheld Global Positioning System (GPS), field study and validation were performed for almost 20% (30 locations) of the detected landslide locations and the results revealed that the landslide locations were correctly detected. In conclusion, this study can be applicable for hazard mitigation purposes and regional planning

Tectonic Geodesy: An Analysis of the Crustal Deformation of the Western Sundaland Plate from Nearly Two Decades of continuous GPS Measurements

The Sundaland plate (hereinafter, Sunda plate) is located in a tectonically active region where the Eurasia, India-Australia, Yangtze, Burma, Molucca Sea, Banda Sea, and Timor plates converge and share common boundaries. It is known that great earthquakes typically rupture along subduction plate boundaries, and this is the case for the Sunda megathrust. On 26th December 2004, a thrust earthquake of Mw 9.0 that ruptured a ~1,300 km long segment, initiated from off the coast of northern Sumatra (Aceh) to the south of Andaman Island, and marked the beginning of an active seismological period. Three months later, another thrust earthquake of Mw 8.6 ruptured to the south of the 2004 event. Further south, the 2007 Mw 8.5 Bengkulu thrust earthquake ruptured off the shore of Bengkulu and had two massive aftershocks of Mw 7.9 and Mw 7.0 in less than 24 hours’ following the event. Most recently, the 2012 Mw 8.6 and Mw 8.2 Wharton Basin (WB) strike-slip earthquakes ruptured a diffuse boundary of the Indian and Australian plate that accommodates the present-day plate motion of the Sunda plate. This dissertation presents the geodetic analysis of 143 continuous GPS (cGPS) measurements that span a large region of the Sunda plate, including Indonesia (Sumatra), Malaysia (Peninsular Malaysia, Sabah and Sarawak), India (Nicobar–Andaman Islands), Thailand, the Philippines and Singapore, between 1999.0 and 2015.9. During the 2004 and 2005 earthquakes, the cGPS measurements recorded significant coseismic displacements and postseismic deformation in the western margin of the Sunda plate. Subsequently, the regional velocity field for distances of up to 1,400 km from the epicentre shows a clear deviation from the course of motion of prior to the 2004 and 2005 earthquake events, implying that a significant postseismic relaxation process is undergoing in the elastic crust and the underlying mantle. The velocity field deviation has decreased significantly following the 2012 Wharton Basin strike-slip earthquakes, which postseismic of 2012 earthquake is reaching closer to the interseismic state. The geodetic-based strain rate field indicates a high shear strain rate following the 2004 and 2005 megathrust earthquakes, mainly concentrated on the Sunda forearc at the segment north of the equator. It is likely to be caused by postseismic relaxation from both ruptures, which produces a complex deformation pattern on the overriding plate surface. The dilatation strain rate analysis reveals localised subsidence in northern Kelantan, a northeast coast state in the Peninsular Malaysia, which is likely induced by groundwater extraction. The region shows higher ground deformation rates (0.22 ppm/yr) than the other parts of Peninsular Malaysia. The observed vertical measurements indicated a maximum subsidence rate of 4.22±0.17 mm/yr (1 confidence level), as well as a corresponding horizontal deformation signal that manifests as high shear strain rate. Dilatation strain rate analysis shows a contraction pattern along the SW-NE trend of the Kelantan River, associated with the extensional pattern as moving further away from the river. A study of the interseismic plate locking coefficient also reveals that the subduction interface for this segment, which was fully locked before the 2004 and 2005 earthquakes is freely slipping after the ruptures. The present-day (2007–2016) interseismic velocity fields have shown that this segment of the plate is now regaining locking with >0.5 coupling coefficient. While to the south, the plate interface along the Siberut segment was locked before the 2007 Bengkulu earthquake and it remains partially locked after the rupture. This finding is also consistent with published results, that suggest that the 2007 ruptures only slipped a part of the rupture length of the 1797 and 1833 earthquakes. This study reveals the temporal variation of the coupling coefficient along the Sunda subduction interface following the series of great earthquakes. The coseismic displacements are inverted to study two key ruptures, the 2004 Aceh earthquake and 2012 Wharton Basin earthquakes since they have significant effect on the present-day geodynamics of the Sunda plate. The preferred model in this study agrees with the published models that the 2004 Aceh earthquake ruptured an at least 1,300 km long segment along the Sunda subduction trench, and it resulted in a moment of 4.3×1022 Nm and the moment magnitude of Mw 9.0. The recent 2012 strike-slip earthquake shows a preference fault rupture of NNE trending. The rupture may have triggered some motion on the Sunda subduction interface, that is suggested to be one of the contributing sources for the small-scale tsunami that was recorded at the regional tide gauges

The State of Remote Sensing Capabilities of Cascading Hazards Over High Mountain Asia

Cascading hazard processes refer to a primary trigger such as heavy rainfall, seismic activity, or snow melt, followed by a chain or web of consequences that can cause subsequent hazards influenced by a complex array of preconditions and vulnerabilities. These interact in multiple ways and can have tremendous impacts on populations proximate to or downstream of these initial triggers. High Mountain Asia (HMA) is extremely vulnerable to cascading hazard processes given the tectonic, geomorphologic, and climatic setting of the region, particularly as it relates to glacial lakes. Given the limitations of in situ surveys in steep and often inaccessible terrain, remote sensing data are a valuable resource for better understanding and quantifying these processes. The present work provides a survey of cascading hazard processes impacting HMA and how these can be characterized using remote sensing sources. We discuss how remote sensing products can be used to address these process chains, citing several examples of cascading hazard scenarios across HMA. This work also provides a perspective on the current gaps and challenges, community needs, and view forward toward improved characterization of evolving hazards and risk across HMA

Impact of rubber tree dominated land-use on biodiversity and ecosystem services in the Greater Mekong Subregion

Die vorliegende Dissertation analysiert den Einfluss von steigendem Kautschukanbau (Hevea brasiliensis) hinsichtlich Biodiversität und Ökosystemdienstleistungen (ÖSD) in der Greater Mekong Subregion. Kautschukplantagen beeinflussen die Bereitstellung verschiedener Ökosystemdienstleistungen wie Kohlenstoffspeicherung, Wasserverfügbarkeit und qualität und beeinträchtigt die Biodiversität. Um diese Einflüsse zu untersuchen war die erste Aufgabe die Erstellung eines Überblicks über Veröffentlichungen bezüglich ÖSD und Biodiversität in Kautschuk-Anbaugebieten. Die Literaturübersicht zeigte, dass die Mehrzahl der Publikationen nur eine einzige oder sehr wenige ÖSD behandelt. Dies entspricht nicht den Anforderungen von Entscheidungsträgern, die für fundierte Entscheidungen hinsichtlich Landnutzungsplanung oder die Entwicklung von Zahlungen für ÖSD ein holistisches Bild brauchen, das mehrere ÖSD simultan betrachtet. Um einen Beitrag zu einer holistischeren Sichtweise zu leisten, war die zweite Aufgabe die Analyse des Einflusses von Kautschuk auf die ÖSD Kohlenstoffspeicherung, Bodenerosion, Wasserverfügbarkeit und -qualität, sowie Einkommen und Existenzsicherung. Obwohl es bezüglich der Kohlenstoffbindung in verschiedenen Landnutzungsformen noch große Unsicherheiten gibt, verdichten sich die Hinweise darauf, dass in Kautschukplantagen weniger Kohlenstoff gespeichert ist, als in natürlichen Wäldern. Das Risiko von Erodibilität von Böden in Kautschukanlagen ist im Vergleich zu natürlichen Wäldern höher. Der lokale und regionale Wasserkreislauf wird von Kautschukplantagen ebenfalls beeinflusst. Die Wasserqualität für Menschen und wasserlebende Organismen wird ebenfalls beeinträchtigt. Zweifelsfrei hat die Einführung von Kautschuk eine signifikante Steigerung des Farmeinkommens bewirkt. Allerdings legen sich die Bauern mit der Kautschukproduktion auf Jahrzehnte fest und sind somit abhängig von einer einzelnen Kultur. Weitere ökologische Gefahren bestehen durch Pflanzenkrankheiten und schädlinge, ungünstige Witterung oder Klimaveränderung. Die Auswertung der Studien zeigte deutlich, dass der zunehmende Kautschukanbau in der GMS von verschiedenen Problemen und Bedrohungen für die Bauern und die Umwelt begleitet wird. Die Entwicklung von nachhaltigen Landnutzungskonzepten ist daher unabdingbar. Aufgrund der beschriebenen Ergebnisse basieren Vorschläge für eine nachhaltigere Landnutzung auf Diversifizierung der Plantagen und die Wiederaufforstungen von Wäldern, beides erfordert aber ökonomische Anreize für die Bauern. Ein weiterer Teil der Dissertation behandelt die Entwicklung eines Biodiversitäts-Indikators, der in bestehenden Biodiversitätsmodellen verwendet werden kann. Unser Datensatz umfasste Flora, Vertebraten und Invertebraten. Der resultierende Indikator wurde als Eingabe in ein bestehendes Modell zur Bewertung von ÖSD verwendet. Abschließend wurde eine Landnutzungskarte aus dem Jahr 2007 mit zwei Szenarien verglichen. Um ein differenzierteres Bild zu erhalten wurden zusätzlich Untergruppen analysiert. Die erste Untergruppe Arten für den menschlichen Gebrauch beinhaltete nur die Arten, die der Mensch direkt nutzt (Wildbienen für die Honigproduktion und Pflanzen für Traditionelle Chinesische Medizin). Die zweite Unter-gruppe Rote Liste Arten, bestehend aus Pflanzen und Säuger die auf der roten Liste verzeichnet sind, wurde getrennt untersucht, um Naturschutzaspekte mit einzubeziehen. Die Ergebnisse zeigten, dass es bei einer Beschränkung auf die Arten für den menschlichen Gebrauch weniger Unterschiede zwischen den Szenarien gibt, da die Medizinalpflanzen auch in Kautschukplantagen vorkommen, wenn auch mit anderen Arten (Generalisten und Ruderalpflanzen). Dies führt zu einer wichtigen Schlussfolgerung: Allein die Entscheidung Was untersucht wird ist nicht ausreichend (Biodiversität), sondern auch das Wie (Gruppierung von verschiedenen Artgruppen) ist wichtig, da es erhebliche Auswirkungen auf die Ergebnisse hat. In einem letzten Aspekt wurde die Übertragbarkeit der Projektergebnisse auf andere Regionen der Welt untersucht, um die Relevanz des Kautschukanbaus auch für Gebiete außerhalb des eigentlichen Untersuchungsgebietes zu ermitteln. Dafür wurde das System der Land-Archetypen benutzt, das eine große Auswahl von Landnutzungsintensitäten verwendet und gleichzeitig ökologische und sozio-ökonomische Gegebenheiten mit einbezieht. In einem ersten Schritt wurde der Projekt-Archetyp definiert, basierend auf der Zusammenführung von globalen Indikatoren mit deren Hilfe Landnutzung und Landeigenschaften beschrieben werden können. Für das Verbundprojekt Sustainable Rubber Cultivation in the Mekong Region wichen nur wenige der 32 untersuchten globalen Indikatoren von den realen lokalen Werten ab. Das Übertragbarkeitspotenzial für die GMS war relativ hoch und unterstützt damit die Wichtigkeit der Projektergebnisse für diese große Region.The present dissertation analyzes the impact of rubber tree (Hevea brasiliensis) dominated land-use on biodiversity and ecosystem services (ESS) in the Greater Mekong Subregion (GMS). Although originating from South-America natural rubber is mainly cultivated in South-East Asia. This expansion of rubber plantations affects different ESS such as carbon storage, availability and quality of water and threatens biodiversity in this highly biodiverse region. In order to analyze these impacts the first task was to give a comprehensive overview about publications concerning ESS and biodiversity in rubber cultivation systems. A thorough literature review showed that the majority of publications concentrated on single or few ESS, which does not match the demands of decision-makers. In order to make sound decisions for land-use planning or developing Payments for Ecosystem Services Schemes a holistic view including multiple services. In order to fill this knowledge gap, the second task was to analyze the impacts of rubber on the ESS carbon storage, soil erosion, water availability and water quality and economically and socially related ESS, such as income and livelihood security. Although there are still great uncertainties about carbon storage in different land-use systems there are hints that the carbon storage in rubber plantations is lower than in natural forests. Concerning erodibility, rubber plantations increase the soil erosion risk compared to natural forests. Rubber cultivation also affects the local and regional water balance. Since rubber production in monocultures requires the use of huge amounts of pesticides and chemical fertilizers which enter the aquatic system by rainfall-induced run-off, water quality for humans and aquatic organisms is as well threatened. Undoubtedly, from an economic point of view the introduction of rubber resulted in significant increases in household income and is hence a possibility to move households and communities out of poverty. However, by deciding to grow rubber, farmers are committing themselves for decades to come and are thus dependent on a single product, which exposes them to further risks. In addition, there are ecological hazards due to crop diseases, pests, unfavorable weather conditions or changes in climate. The review of studies clearly indicates that increasing rubber cultivation in the GMS is accompanied by various problems and threats to farmers and the environment. Therefore, the development of more sustainable land-use concepts is required. Concordantly, suggestions for land-use change are based on system diversification and forest restoration, which both require economic incentives for farmers. The next part of this dissertation deals with the development of a biodiversity indicator (based on selected flora and fauna species) that can be included in existing biodiversity models to show the impact that different rubber cultivation scenarios will have on various species groups. A combination of multi-species data supplemented with literature data was used and included flora, vertebrates and invertebrates. The resulting indicator was used as input into an established ESS assessment framework. Finally, a current land-use map from 2007 was compared with two scenarios. In order to get a more detailed picture, sub-groups of biodiversity were analyzed as well. First, a sub-group of human use species category was assessed which included only species which are directly used by humans. Second, the sub-group red list species, consisting of red list plants and mammals was analyzed separately to include the conservational aspect. The results showed that when considering the indices from the category human use species there is less of an impact between the scenarios, because medicinal plants for example are still commonly distributed within rubber plantations, albeit with different species (generalists, ruderal flora). This leads to an important conclusion: not only the decision on what is analyzed (biodiversity), but also how it is analyzed (groups of different species) considerably influences the results. To complete this dissertation the transferability of this place-based research to other regions of the world was tested to assess the relevance beyond the study area. To do this the system of land archetypes was used, which utilizes a wide range of land-use intensity metrics and incorporates simultaneously environmental and socio-economic conditions. In a first step, the project archetype was defined, based on a synthesis of global land system indicators. For the project Sustainable Rubber Cultivation in the Mekong Region, only few of the 32 global indicators did not closely match the local reality. The transferability potential for the GMS was quite high and therefore emphasizes the importance of the project results for this huge region

Semantic location extraction from crowdsourced data

Crowdsourced Data (CSD) has recently received increased attention in many application areas including disaster management. Convenience of production and use, data currency and abundancy are some of the key reasons for attracting this high interest. Conversely, quality issues like incompleteness, credibility and relevancy prevent the direct use of such data in important applications like disaster management. Moreover, location information availability of CSD is problematic as it remains very low in many crowd sourced platforms such as Twitter. Also, this recorded location is mostly related to the mobile device or user location and often does not represent the event location. In CSD, event location is discussed descriptively in the comments in addition to the recorded location (which is generated by means of mobile device's GPS or mobile communication network). This study attempts to semantically extract the CSD location information with the help of an ontological Gazetteer and other available resources. 2011 Queensland flood tweets and Ushahidi Crowd Map data were semantically analysed to extract the location information with the support of Queensland Gazetteer which is converted to an ontological gazetteer and a global gazetteer. Some preliminary results show that the use of ontologies and semantics can improve the accuracy of place name identification of CSD and the process of location information extraction

Application of PALSAR-2 remote sensing data for structural geology and topographic mapping in Kelantan river basin, Malaysia

Natural hazards of geological origin are one of major problem during heavy monsoons rainfall in Kelantan state, peninsular Malaysia. Several landslides occur in this region are obviously connected to geological and topographical features, every year. Satellite synthetic aperture radar (SAR) data are particularly applicable for detection of geological structural and topographical features in tropical conditions. In this study, Phased Array type L-band Synthetic Aperture Radar (PALSAR-2), remote sensing data were used to identify high potential risk and susceptible zones for landslide in the Kelantan river basin. Adaptive Local Sigma filter was selected and applied to accomplish speckle reduction and preserving both edges and features in PALSAR-2 fine mode observation images. Different polarization images were integrated to enhance geological structures. Additionally, directional filters were applied to the PALSAR-2 Local Sigma resultant image for edge enhancement and detailed identification of linear features. Several faults, drainage patterns and lithological contact layers were identified at regional scale. In order to assess the results, fieldwork and GPS survey were conducted in the landslide affected zones in the Kelantan river basin. Results demonstrate the most of the landslides were associated with N-S, NNW-SSE and NE-SW trending faults, angulate drainage pattern and metamorphic and Quaternary units. Consequently, geologic structural map were produced for Kelantan river basin using recent PALSAR-2 data, which could be broadly applicable for landslide hazard assessment and delineation of high potential risk and susceptible areas. Landslide mitigation programmes could be conducted in the landslide recurrence regions for reducing catastrophes leading to economic losses and death