Steep Topography Research Articles

Geological and geomechanical evidence from the Sünnet landslides (NW Anatolia) for an Mw8.0 cascade rupture in the North Anatolian Fault 8 ky ago

Although the North Anatolian Fault is one of the most investigated continental transform faults across the globe, the maximum earthquake magnitude (Mmax) expected and the resulting seismic risk to the nearby big settlements is still a matter of debate. Some part of the problem issues from the relatively short paleoseismological record of this fault while the rest is closely related to the uncertainties of probable multiple segment ruptures. This study addresses this issue through the investigation of the Sünnet-W landslide in terms of age and dynamic triggering conditions in NW Anatolia where similar large bedrock failures abound. This landslide is a rotational failure with a volume of 5.75 million m3 and developed in the Jurassic-Cretaceous carbonate successions 16 km off the NAF. Radiocarbon dating of the earliest sediments of the associated dam lake upstream yields a calibrated age of 8000 ± 35 yr BP for the landslide formation. Pseudo-static back analysis of the failure based on the pre-slide morphology, strength, and discontinuity density of the bedrock revealed horizontal accelerations of 0.484 g and 0.976 g for the initiation of failure. The steep topography and especially the height of the failed slope imply that a topographic amplification of 1.5 times would be reasonable based on the previous numerical models. Moreover, the paleoclimatological conditions of the time are estimated not to be sufficient for the complete saturation of the deep sliding surface. Even after the consideration of these site-specific encouraging conditions, a threshold magnitude of about 8.0 for the triggering earthquake of the Sünnet-W landslide is suggested. This estimate is at least six times larger than the anticipation of the previous paleoseismological studies (M7.4) from the western part of the NAF. We suggest that the triggering earthquake of the Sünnet landslides 8 ky ago may have been a huge cascade rupture that involves many, if not all, of the segments between Erdek and Niksar along the western and central NAF. This type of multi-segment rupture was previously conceptualized throughout the NAF but remained unexemplified up to date. The present study demonstrates that they should be seriously traced in far-reaching paleoseismological records due to their huge impacts on the seismic hazard of the region.

Improving Youth Preparedness in Facing Floods and Landslides Through the Team Games Tournament Method

The most frequent disasters in Jember are floods. The most severely affected area is Panti District. The flash floods and landslides in Panti sub-district in 2006 resulted in loss of life and large property losses. This is caused by bare forest vegetation, steep slope topography, and prolonged high rainfall. The population that is vulnerable to disasters is youth. The purpose of this study was to increase youth preparedness knowledge at MTs SA Miftahul Ulum, Sodong Hamlet, Kemiri Village, Panti District in dealing with floods and landslides. The method of providing education is carried out by means of a Team Games Tournament (TGT). Evaluation was carried out using a one group pre-test post-test design. The results obtained were that the value of youth preparedness knowledge significantly increased (p-value <0.001). The TGT method has proven to be effective in increasing disaster preparedness knowledge because the absorption of the material is easier to understand and accept and students are more active in participating during the process of delivering the material.

Suitability of Tourism Zone Based on Oceanographic Characteristics and Coastal Ecosystems in Sendang Biru Waters and Sempu Island, Malang Regency

Sendang Biru Tourism Beach and Sempu Island are tourism zones based on East Java Provincial Regulation No. 1 of 2018, which are part of the Sempu Strait, Malang Regency. Tourism activities depend on the quality of natural resources as the main tourism commodity. Activities that do not match or exceed the area's carrying capacity will also pressure coastal and water resources. This study aimed to determine the suitability of oceanographic and ecosystem characters in tourism zones as parameters for suitability. This study collects secondary and primary data obtained in January 2021, and the method of analysis uses the overlapping technique of physical and biological parameters. The study results show that these waters have a sloping - steep topography with tidal types is mixed tide prevailing semidiurnal, and a current type with a slow - medium category and conditions of temperature, salinity, and pH are still suitable for aquatic ecosystem life. The tourism zone of Sendang Biru Beach and Sempu Island has an oceanographic character that supports coastal tourism activities and ecosystem life, and aquatic biota. However, the existing ecosystem conditions less support coastal tourism activities in these waters. Based on the analysis, it appears that some coastal areas are suitable and very suitable for coastal tourism activities, and the ecotourism concept is recommended for coastal tourism activities.

Generation of Extreme Precipitation over the Southeastern Tibetan Plateau Associated with TC Rashmi (2008)

Abstract In this study, the development of an extreme precipitation event along the southeastern margin of the Tibetan Plateau (TP) by the approach of Tropical Cyclone (TC) Rashmi (2008) from the Bay of Bengal is examined using a global reanalysis and all available observations. Results show the importance of an anomalous southerly flow, resulting from the merging of Rashmi into a meridionally deep trough at the western periphery of a subtropical high, in steering the storm and transporting tropical warm–moist air, thereby supplying necessary moisture for precipitation production over the TP. A mesoscale data analysis reveals that (i) the Rashmi vortex maintained its TC identity during its northward movement in the warm sector with weak-gradient flows; (ii) the extreme precipitation event occurred under potentially stable conditions; (iii) topographical uplifting of the southerly warm–moist air, enhanced by the approaching vortex with some degree of slantwise instability, led to the development of heavy to extreme precipitation along the southeastern margin of the TP; and (iv) the most influential uplifting of the intense vortex flows carrying ample moisture over steep topography favored the generation of the record-breaking daily snowfall of 98 mm (in water depth), and daily precipitation of 87 mm with rain–snow–rain changeovers at two high-elevation stations, respectively. The extreme precipitation and phase changeovers could be uncovered by an unusual upper-air sounding that shows a profound saturated layer from the surface to upper troposphere with a moist adiabatic upper 100-hPa layer and a bottom 100-hPa melting layer. The results appear to have important implications to the forecast of TC-related heavy precipitation over high mountains. Significance Statement This study attempts to gain insight into the multiscale dynamical processes leading to the development of an extreme precipitation event over the southeastern margin of the Tibet Plateau as a Bay of Bengal tropical cyclone (TC) approached. Results show (i) the importance of an anomalous southerly flow with a wide zonal span in steering the relatively large-sized TC and transporting necessary moisture into the region; and (ii) the subsequent uplifting of the warm and moist TC vortex by steep topography, producing the extreme precipitation event under potentially stable conditions, especially the record-breaking daily snowfall of 98 mm (in water depth). The results have important implications to the forecast of TC-related heavy precipitation over the Tibet Plateau and other high mountainous regions.

Diffusive wave models for operational forecasting of channel routing at continental scale

AbstractOperational forecast models require robust, computationally efficient, and reliable algorithms. We desire accurate forecasts within the limits of the uncertainties in channel geometry and roughness because the output from these algorithms leads to flood warnings and a variety of water management decisions. The current operational Water Model uses the Muskingum‐Cunge method, which does not account for key hydraulic conditions such as flow hysteresis and backwater effects, limiting its ability in situations with pronounced backwater effects. This situation most commonly occurs in low‐gradient rivers, near confluences and channel constrictions, coastal regions where the combined actions of tides, storm surges, and wind can cause adverse flow. These situations necessitate a more rigorous flow routing approach such as dynamic or diffusive wave approximation to simulate flow hydraulics accurately. Avoiding the dynamic wave routing due to its extreme computational cost, this work presents two diffusive wave approaches to simulate flow routing in a complex river network. This study reports a comparison of two different diffusive wave models that both use a finite difference solution solved using an implicit Crank–Nicolson (CN) scheme with second‐order accuracy in both time and space. The first model applies the CN scheme over three spatial nodes and is referred to as Crank–Nicolson over Space (CNS). The second model uses the CN scheme over three temporal nodes and is referred to as Crank–Nicolson over Time (CNT). Both models can properly account for complex cross‐section geometry and variable computational points spacing along the channel length. The models were tested in different watersheds representing a mixture of steep and flat topographies. Comparing model outputs against observations of discharges and water levels indicated that the models accurately predict the peak discharge, peak water level, and flooding duration. Both models are accurate and computationally stable over a broad range of hydraulic regimes. The CNS model is dependent on the Courant criteria, making it less computational efficient where short channel segments are present. The CNT model does not suffer from that constraint and is, thus, highly computationally efficient and could be more useful for operational forecast models.

A Decade after Typhoon Morakot (2009): What Have We Learned about Its Physics and Predictability?

Abstract Typhoon Morakot struck Taiwan during 7–9 August 2009 and became the deadliest tropical cyclone (TC) in five decades by producing up to 2635 mm of rain in 48 h, breaking the world record. The extreme rainfall of Morakot resulted from the strong interaction among several favorable factors that occurred simultaneously. These factors from large scale to small scale include the following: 1) weak environmental steering flow linked to the evolution of the monsoon gyre and consequently slow TC motion; 2) a strong moisture surge due to low-level southwesterly flow; 3) asymmetric rainfall and latent heating near southern Taiwan to further reduce the TC’s forward motion as its center began moving away from Taiwan; 4) enhanced rainfall due to steep topography; 5) atypical structure with a weak inner core, enhancing its susceptibility to the latent heating effect; and 6) cell merger and back building inside the rainbands associated with the interaction between the low-level jet and convective updrafts. From a forecasting standpoint, the present-day convective-permitting or cloud-resolving regional models are capable of short-range predictions of the Morakot event starting from 6 August. At longer ranges beyond 3 days, larger uncertainty exists in the track forecast and an ensemble approach is necessary. Due to the large computational demand at the required high resolution, the time-lagged strategy is shown to be a feasible option to produce useful information on rainfall probabilities of the event.

Scalings for Eddy Buoyancy Fluxes Across Prograde Shelf/Slope Fronts

AbstractDepth‐averaged eddy buoyancy diffusivities across continental shelves and slopes are investigated using a suite of eddy‐resolving, process‐oriented simulations of prograde frontal currents characterized by isopycnals tilted in the opposite direction to the seafloor, a flow regime commonly found along continental margins under downwelling‐favorable winds or occupied by buoyant boundary currents. The diagnosed cross‐slope eddy diffusivity varies by up to three orders of magnitude, decaying from in the relatively flat‐bottomed region to over the steep continental slope, consistent with previously reported suppression effects of steep topography on baroclinic eddy fluxes. To theoretically constrain the simulated cross‐slope eddy fluxes, we examine extant scalings for eddy buoyancy diffusivities across prograde shelf/slope fronts and in flat‐bottomed oceans. Among all tested scalings, the GEOMETRIC framework developed by D. P. Marshall et al. (2012, https://doi.org/10.1175/JPO-D-11-048.1) and a parametrically similar Eady scale‐based scaling proposed by Jansen et al. (2015, https://doi.org/10.1016/j.ocemod.2015.05.007) most accurately reproduce the diagnosed eddy diffusivities across the entire shelf‐to‐open‐ocean analysis regions in our simulations. This result relies upon the incorporation of the topographic suppression effects on eddy fluxes, quantified via analytical functions of the slope Burger number, into the scaling prefactor coefficients. The predictive skills of the GEOMETRIC and Eady scale‐based scalings are shown to be insensitive to the presence of along‐slope topographic corrugations. This work lays a foundation for parameterizing eddy buoyancy fluxes across large‐scale prograde shelf/slope fronts in coarse‐resolution ocean models.

Distribution feature and development characteristics of geohazards in Wudu district, Gansu province, Northwest China

BackgroundThe study area located at southeast Gansu, China, has long been afflicted by the intense occurrence of geohazards. The study area is characterized by interleaving terrain of precipitous mountains and valley basins, abundant precipitation, and complicated geological setting. In this work, 1144 geohazards including 759 landslides, 281 debris flows, and 104 collapse were presented and their types were categorized in detail. Then, the distribution of geohazards were analyzed and the controlling role of hazard-inducing environment and triggering factors on geohazards were preliminary presented.ResultsIn this work, correlation analysis between geohazards and geological, topographical, and geomorphological context was conducted. Concave slopes with height smaller than 200 m and slope gradient between 21° and 40° is the favorable topographic feature for landslide occurrence and the predominant slope aspects of landslides are southwest, south, west, and southeast. Collapse generally occurs in slope with gradient larger than 45°. Valleys with valley gradient less than 400‰, valley height between 100 and 500 m, and watershed area of 1–10 km2 register the largest percentage and the most favorable slope gradient for the supply of solid source at the debris flow source area is 25°–45°. The preferable strata for geohazards (landslide, collapse and debris flow) are Middle and upper Pleistocene loess, Holocene diluvium, Silurian phyllite and slate, Neogene mudstone, and Devonian schist and gneiss, and most geohazards occurred in tectonic erosional middle altitude mountain, tectonic erosional high-middle altitude mountain, tectonic erosional-diluvial planation surface. In addition, the controlling role of triggering factors, i.e., precipitation, earthquake, and human engineering activity was discussed and described in this work.ConclusionGeohazards in the study area are synthetically controlled by the hazard-inducing environment and triggering factors. The complicated sliding-prone strata and steep topography resulted from strong tectonic movement provides a favorable basis for the development and formation of geohazards. Heavy rainfall, strong seismic motion, and human engineering activity are the main triggering factors for geohazard occurrence.

On the selection of turbulent model for the nearshore hydrodynamics modeling of coral reefs: Insight from an inter-comparison study

Natural coral reefs generally have rough and undulating topography. Due to the steep and variable topography from the deep to shallow water near the starting point of reef flats, the wave motion is quite complex and there are severe wave rolling and breaking on reef flats. To credibly simulate the wave evolution on reef flats, and the hydrodynamic performance of revetment breakwaters built on coral reefs, a suitable turbulence model is needed in the numerical simulation. In this study, a series of hydrodynamic numerical simulations with various RANS turbulence models are conducted adopting OlaFlow solver as the computational platform. The numerical results from three turbulence models, i.e. the standard k-ε, the buoyancy-modified k-ω SST, and the stabilized k-ω SST, are analyzed and evaluated utilizing different grid systems, where the grid number is 1.40, 2.37 and 3.52 million, respectively. By comparing the numerical results from the three different turbulence models, it is found that the stabilized k-ω SST turbulence model could give consistent and good results for the complex evolution process of waves on reef flats, and give acceptable results for the wave impact on structures. In contrast, the numerical results from the standard k-ε and the buoyancy-modified k-ω SST models present significant grid dependencies, indicating that the credibility of these results is doubtful. On the aspect of capturing the wave breaking and run-up, the results from the buoyancy-modified k-ω SST and the stabilized k-ω SST models are remarkably better than that from the standard k-ε model. As for the overtopping volume over breakwater, all three turbulence models present serious grid dependence and fail to obtain consistent numerical results. Finally, it is recognized that the stabilized k-ω SST model is a suitable turbulence model for the nearshore hydrodynamics modeling of coral reefs.

Tc-cylinder: An optimized algorithm for accurate topography effect from high-resolution digital elevation models

An efficient algorithm, tc-cylinder, has been developed to obtain terrain corrections by considering computational efficiency, data storage and use, spherical curvature effects, water bodies, etc. High resolution Digital Elevation Models (DEMs) are fundamental data sources for accurate terrain corrections. But a high-resolution DEM like SRTM1 poses some difficulties during processing, such as data storage, handling, efficiency and computation speed over large areas. In order to overcome these issues, a shortened computation area radius (e.g., 50 km) is preferred for practical studies. This kind of limitation may cause an accuracy loss of over 20 mGal in steep topography. Similarly, spectral methods used to speed up the computations have drawbacks in areas with high slopes. The presented algorithm for segmenting cylinder bodies proves more realistic and effective terrain correction results in all physical conditions. An optimization approach that belongs to the Intel’s processor and compiler architecture improved processing efficiency by a factor of 2.5 times with non-temporal stores, which copies large data directly to memory. Synthetic masses based on known geometric bodies were considered to test program efficiency and numerical results. The contribution was examined at gravity stations in the Konya Closed Basin, which has a sophisticated topography. Additionally, an investigation was conducted in extreme conditions, such as Everest Mountain and the Ağrı Mountain in Turkey, with abrupt elevation profile changes. The numerical analyses of the accuracy of terrain correction values is performed on different combinations of DEM resolutions. Consequently, it is verified that 1′′ inner and 15′′ outer grid resolutions lead to sub-mGal accuracy with less processing time, even in rough topography.

Observation of Bottom-Trapped Topographic Rossby Waves to the West of the Luzon Strait, South China Sea

Abstract Topographic Rossby waves (TRWs) play an important role in deep-ocean dynamics and abyssal intraseasonal variations. Observational records from 15 current- and pressure-recording inverted echo sounders (CPIESs) and two moorings deployed in the northern Manila Trench (MT), South China Sea (SCS), for over 400 days were utilized to analyze the widely existing near-21-day bottom-trapped TRWs in the trench. The TRWs were generally generated in winter and summer, dominated by perturbations in the upper ocean. Kuroshio intrusion and its related variabilities contributed to the perturbations in winter, whereas the perturbations generated north of Luzon Island dominated in summer. Eddies north of Luzon propagated northwestward in the summer of 2018; however, these eddies caused the Kuroshio meanderings in the Luzon Strait (LS) in the summer of 2019. The variations in the Kuroshio path and the Kuroshio-related eddies induced TRWs in the deep ocean in regions with steep topography. However, the spatiotemporal distributions of TRWs were complex owing to the propagation of the waves. Some cases of TRWs showed no relation to the local upper-layer perturbations but propagated from adjacent regions. Some of these TRWs were induced by perturbations in the upper ocean in adjacent regions, and propagated anticlockwise in the MT with shallow water to their right, while others may be related to the intraseasonal variations in deep-water overflow in the LS and propagated northward. This study suggests that the Kuroshio and Kuroshio-related eddies significantly contribute to the dynamic processes associated with intraseasonal variations in the deep SCS through the generation of TRWs. Significance Statement Topographic Rossby waves (TRWs) are fluctuations generated when water columns travel across sloping topography under potential vorticity conservation. Based on observations of 15 current- and pressure-recording inverted echo sounders (CPIESs) and two moorings in the northern Manila Trench (MT) in the South China Sea (SCS), TRWs with periods of approximately 21 days were observed and analyzed. This study describes the generation, propagation, and spatiotemporal distribution of TRWs west of the LS and confirms that regional Kuroshio meanderings and upper eddies play important roles in the dynamic processes associated with intraseasonal variations in the deep SCS; the study may thus contribute to knowledge on the dynamic response of the abyssal current to mesoscale perturbations in the upper ocean.

Crescent-Shaped Low-Temperature Distribution along the Convex Topography in the Southeastern Edge of Taiwan Bank in Summer

Abstract Various physical mechanisms of ocean upwelling usually occur near or along coastal regions worldwide. Five upwelling zones of unequal intensity are found around the Taiwan Strait, and the Taiwan Bank (TB) upwelling zone has the most prominent characteristics of low temperature. In this study, satellite images, shipboard ADCPs (acoustic Doppler current profilers), and CTDs (conductivity–temperature–depth measures) were analyzed to investigate the processes of cold water upwelling around the TB shoaling zone. In addition, the MITgcm numerical model and the flexible cubic spline technique were also employed, allowing us to better understand those processes. The model results suggested that a combination of Ekman transport and the centrifugal force, driven by the geostrophic South China Sea Warm Current (SCSWC), constitutes a physical mechanism to contribute the vigorous upwelling in the TB shoal zone. The upwelling is largely driven by Ekman transport. However, the centrifugal force may explain why the upwelling with a crescent-shaped distribution of low temperatures along the convex topography of the southeastern edge of the TB shoaling zone is more prominent than expected, as it tends toward the so-called gradient wind balance. Sudden relaxation of the friction force occurred because of the very sharp shelf break (20–60 m) and steep slope topography; a discontinuous velocity zone around the shelf break could also lead to vigorous cold water upwelling. Significance Statement Extensive data concerning the Taiwan Bank (TB) shoaling zone have been collected in the past decade in an attempt to improve understanding of the process of cold water upwelling in the area. Because the Kuroshio invades the South China Sea from the east, and the South China Sea Warm Current flows northeastward around the southeastern edge of the TB, water circulation in and around the sandbar is very complicated. Thus, we expanded our model range from small to large scale to avoid the open boundary settings of small-scale model (including the temperature and salinity fields, wind stress, and the model driving forces), which were not easy to set up. Thus, we used a large-scale, high-resolution circulation model to study a small-scale ocean region. Physical processes of this upwelling can finally be verified in the small-scale region. To compensate for the insufficient resolution of the large-scale numerical model, our strategy was to utilize the flexible cubic spline technique to resolve the curvature of the markedly meandering currents. In light of scale analysis, the results showed that in addition to the critical contribution of Ekman transport to the upwelling, the effects of centrifugal forces on upwelling in the TB shoal zone need to be considered.

The Utilisation of Electrical Resistivity Imaging (ERI) for Geological Structures Mapping in Rock Mass: A Review

Electrical Resistivity Imaging (ERI) is an in-situ geophysical method widely used in environmental, engineering and hydrogeological explorations due to cost, time, and data coverage efficiency. Traditionally, geotechnical parameters such as discontinuities properties are obtained from rock samples acquired from a borehole. However, it only provides a single information point, costly and time-consuming. Thus, an approach using electrical resistivity to detect the presence of geological structure in a rock mass is an alternative method that can be applied. Discontinuities in rock mass include joints, bedding planes, blasting cracks, fractures, faults, and folds. This paper aims to present the utilisation of geoelectrical resistivity imaging for geological structures mapping in rock mass based on the review from previous research. The Electrical Resistivity Imaging (ERI) method is an effective tool to obtain structural differentiation of geological medium by interpreting 2D and even 3D electrical resistivity models. Electrical Resistivity Imaging (ERI) is an automated data acquisition system, inversion codes, non-invasive and user-friendly. The raw data received from data acquisition was analysed using Res2DINV software. The data inversion was done by applying the robust method and finite element grid to accommodate the steep topography. The data interpretation included numerical modelling to assess the suitability of all used electrode arrays in relation to the geological setting.

Chondrichthyan (Holocephali, Squalomorphii and Batomorphii) remains from the Badenian of southern Hungary (Tekeres, Mecsek Mountains): the first deepwater cartilaginous fishes from the Middle Miocene of the Central Paratethys

AbstractMiddle Miocene (Badenian) chondrichthyan fossils collected from the Tekeres Schlieren Member of the Baden Formation at Tekeres (southern Hungary, Mecsek Mts) are described here. The chondrichthyan assemblage is exceptionally diverse and well‐preserved, and consists of holocephalans, selachians and batomorphs. Nine taxa are reported for the first time from the Badenian of the Central Paratethys: Ischyodus sp., Hexanchus cf. nakamurai, Centrophorus sp., Isistius triangulus, Pristiophorus sp., Sphyrna integra, Raja cf. gentili, Dasyatis cf. pastinaca and Mobula fragilis. The fauna is characterized by many deepwater taxa, making it the first bathyal vertebrate assemblage of the Badenian Central Paratethys. However, typically shallow water, littoral forms are also present, which are worn and often broken, indicating that some of the Tekeres fauna was transported and redeposited from a shallow, coastal setting into deeper water environments. Rapid basin deepening and the resulting steep topography can be linked to ongoing rifting of the south‐west Pannonian Basin. The majority of the studied chondrichthyan fauna have extant representatives in the Mediterranean, which supports an active faunal connection between the Mediterranean and the Central Paratethys via the Slovenian Corridor and the existence of a network of deepwater habitats at least along this pathway.

Impact of Resolution on the Representation of the Mean and Extreme Winds Along Nares Strait

AbstractNares Strait is the long and narrow strait bounded by steep topography that connects the Arctic Ocean's Lincoln Sea to the North Atlantic's Baffin Bay. The winds that blow along the strait play an important role in modulating ice and water exports from the Arctic Ocean as well as in helping to establish the Arctic's largest and most productive polynya that forms at its southern terminus. However, its remote location has limited our knowledge of the winds along the strait. Here we use weather station data from the region as well as two reanalyses and an operational analysis with nominal horizontal resolutions that vary from ∼30 to ∼2.5 km to characterize the wind field in the vicinity of the strait. The strait has a width that varies from ∼40 to ∼100 km and as such the wind field is typically ageostrophic and controlled by the pressure gradient in the along‐strait direction. We show that model resolution plays a role in the representation of both the mean and extreme winds along the strait through the ability to represent this ageostrophic flow. Higher windspeeds occur in the vicinity of Smith Sound and are associated with a left‐hand corner jet. Kane Basin, the widest section of the strait, is characterized by a gradient in windspeed with higher speeds in the center of the basin and lower winds in the eastern basin that is the result of sheltering by the steep topography of the upstream Washington Land peninsula.

Deformation of an infinite elastic cone due to a point pressure source buried on the axis: implications to volcanic deformation

SUMMARY This paper presents a semi-analytical solution describing the deformation of an infinite elastic cone due to a point pressure source buried on the axis. The solution is based on the displacement potentials developed by Love in the spherical coordinate system and is solved as a boundary value problem given on the cone surface using the techniques of Mellin transform. Numerical integration of the inverse Mellin transform yields solutions for various cone angles. The displacements calculated for the cone angle α = 90° are confirmed to agree with the well-known Mogi’s solution for the infinite half-space. The present work will be useful for interpretation of the deformation of volcanoes with steep topography and for verification of other numerical methods.

Considering behavioral state when predicting habitat use: Behavior-specific spatial models for the endangered Tasmanian wedge-tailed eagle

Effective planning for species conservation often requires an understanding of habitat use. The resources an animal selects within the landscape relate to its behavioral state and, therefore, incorporating behavior into habitat selection analyses can help inform management of threatened species. Here we present an approach for developing behavior-specific spatial habitat-use models using large quantities of GPS telemetry data. Using hidden Markov models, we first characterize 231,478 GPS fixes from 22 recently fledged endangered Tasmanian wedge-tailed eagles (Aquila audax fleayi) as reflective of either perching, short-distance flight, or long-distance flight. We then use a multivariate habitat selection ratio to develop spatial models predicting where these behavioral states occur. Recently fledged Tasmanian wedge-tailed eagles selected for areas close to forest edges during perching and short distance flights, whereas they selected more strongly for areas with steep topography (slopes > 15°) and further from forest edges for longer flights. Models using distance to forest edge and topographic slope effectively predicted where eagles engaged in long flights (R2 > 0.91, rs > 0.90) in each of six regions, whereas the performance varied by region for models describing perching (R2 = 0.43–0.97, rs = 0.80–0.97) and short flights (R2 = 0.34–0.93, rs = 0.63–1.00). Our study provides a detailed understanding of habitat use by young Tasmanian wedge-tailed eagles, which has multiple applications in the ongoing conservation of the population. Our method illustrates a framework for spatially explicit and behavior-specific habitat selection analyses that can be applied to other species of conservation concern.

Physical Mechanism for Seabed Scouring around a Breakwater—A Case Study in Mailiao Port

According to a field survey in 2012, the bathymetry near Mailiao Port, located in central Taiwan’s west coast, has a scouring hole that extends approximately 500 m × 100 m with a maximum scour depth of 26 m (eroded from its design depth −22 m to −48 m). To investigate the scour mechanism near the breakwater head and prevent the breakwater from collapsing, this study conducts comprehensive analysis by analyzing field observed data, performing hydraulic model tests, and conducting numerical modeling for the area near the Mailiao Port. The results show that the current plays an important role in the scour process. The physical model tests and numerical simulations both can reproduce the scour phenomenon of the study site. By analyzing field observed data we validated through physical and numerical models. This study concludes that the current caused by the ebb and flood tide, as well as the steep and shallow seabed topography, together comprise the seabed scour mechanism near the Mailiao Port breakwater head.

Higher Water Yield but No Evidence of Higher Flashiness in Tropical Montane Cloud Forest (TMCF) Headwater Streams

There have been conflicting findings on hydrological dynamics in tropical montane cloud forests (TMCFs)—attributed to differences in climate, altitude, topography, and vegetation. We contribute another observation-based comparison between a TMCF (8.53 ha; 1906 m.a.s.l.) and a tropical lowland rainforest (TLRF) (5.33 ha; 484 m.a.s.l.) catchment in equatorial Sabah, Malaysian Borneo. In each catchment, a 90° v-notch weir was established at the stream’s outlet and instrumented with a water-level datalogger that records data at 10-min intervals (converted to discharge). A nearby meteorological station records rainfall at the same 10-min intervals via a tipping bucket rain gauge connected to a datalogger. Over five years, 91 and 73 storm hydrographs from a TMCF and a TLRF, respectively, were extracted and compared. Various hydrograph metrices relating to discharge and flashiness were compared between the TMCF and TLRF while controlling for event rainfall, rainfall intensity, and antecedent moisture. Compared to the TLRF, storm-event runoff in the TMCF was up to 169% higher, reflecting the saturated conditions and tendency for direct runoff. Instantaneous peak discharge was also higher (up to 6.6x higher) in the TMCF. However, despite high moisture and steep topography, stream responsiveness towards rainfall input was lower in the TMCF, which we hypothesise was due to its wide and short catchment dimensions. Baseflow was significantly correlated with API20, API10, and API7. Overall, we found that the TMCF had higher runoff, but higher moisture condition alone may not be sufficient to govern flashiness.

ŞAPHANE (ÇORUM) DAMAR TİPİ ALTIN CEVHERLEŞMESİNDE MULTİSPEKTRAL UYDU GÖRÜNTÜLERİ KULLANILARAK HİDROTERMAL ALTERASYON MİNERAL HARİTALAMASI VE ÇİZGİSELLİK ANALİZİ

Remote sensing techniques provide very useful data for mapping lithological features and minerals, and also revealing structural features. In particular, mapping the distributions of hydrothermal alteration minerals, which is one of the first exploration stages of metallic ore deposits, with less cost and in a short time reveals very important results. In the study area, Eocene volcanic rocks and alterations caused by hydrothermal fluids activities are intensely observed. These intense alterations are associated with gold-bearing hydrothermal veins in approximately NE-SW direction. This area, which has a high gold potential, has a steep topography and is difficult to access. Field studies in the region are carried out with difficulty and many areas can be overlooked during the studies. The mapping of distribution of hydrothermal alteration minerals was carried out by applying the spectral classification method with image enhancement techniques such as vegetation masking (NDVI), and band ratio in ASTER data in this study. In addition, automatic lineament analysis was applied to the 15 m resolution image obtained from the Landsat-8 OLI data for the detection of vein-type mineralizations. The results obtained have an overall accuracy of 84.8 and a kappa coefficient of 0.836, showing high accuracy with field data.It is suggested that the maps obtained in the study will provide useful and advanced data for new gold and/or other precious metallic mineralizations in the region.