Terrain analysis

When rainfall is received on a watershed, depending on the ini al soil moisture content some of the water seeps underground while the excess forms surface water response. The nature of the runoff and its eff ects in the watershed can be represented by the applica on of hydrologic models to predict streamfl ow. In this study, the Geological Streamfl ow Model (GeoSFM) and the Muskingum Cunge (M-C) model were used to model the hydrologic processes of the Yala river network. The objec ve of the study was to develop a fl ood early warning system to mi gate poten al fl ood hazard risk exposed to the downstream inhabitants. Historical hydro-metric datasets of 1975-2005 were used for calibra on, verifi ca on and streamfl ow rou ng based on a split record analysis. For the runoff genera on, rainfall and evapora on datasets were provided by the Kenya Meteorological Department (KMD) while for model calibra on and verifi ca on, streamfl ow was obtained from Water Resources Managemen...

This paper focuses on the effectiveness of the Height Above the Nearest Drainage (HAND) model with the integration of detailed Light Detection and Ranging (LiDAR) data and geographic information systems (GIS) to compute the fluvial flood hazard maps in the Gidra River Basin, western Slovakia. Study area, which is characterized by a wide variety of terrain forms including valleys, hills or lowland, serves as an ideal case study for creating the HAND model. Our approach uses GIS tools to develop digital elevation model (DEM)-based factors crucial for creating the HAND model, such as stream network, flow direction and flow accumulation rasters. Based on the HAND model, it is possible to derive flood-prone areas for any observed water stage measured at gauging stations or with the use of synthetic rating curves for any cross section on the river. This paper aims at outlining the usefulness of GIS and detailed DEM data to produce the HAND model, which is then applied for rapid creation of fluvial flood hazard maps.

Fluvial flooding is characterized by flood discharges, which cause overflowing of the river banks and endangering the adjacent floodplains. In this study, we studied the 3.1 km section of the Gidra River (western Slovakia), which belongs to critical river sections prone to fluvial flooding. We aimed to compare two approaches for fluvial flood hazard mapping. Hydraulic approach was performed with the use of MIKE + model while the GIS-based approach was carried out using the Height Above the Nearest Drainage (HAND) model. The research question was whether the HAND model is suitable for flood inundation modeling and comparable to hydraulic modeling in the specific valley type of terrain. To determine the peak discharges for 100 and 1000 return periods, we used the rainfall-runoff procedure via the STORAGE and COS-MO4SUB models. Accuracy of HAND models, as respect to the hydraulic MIKE + models, was assessed with the use of the following metrics: Critical Success Index, F1-score, Bias, Precision, Recall, and Overall Accuracy. Based on the results, the HAND model underestimated the hydraulically modeled flood extents in case of both flood scenarios with Bias values of 0.84 (Q 1000) and 0.87 (Q 100). The Overall Accuracy resulted in values of 0.93 (Q 1000) and 0.94 (Q 100). We concluded that the HAND-based modeled flood extents for the studied river section had an acceptable accuracy in case of both flood scenarios. Focusing on the river located in a valley type of terrain, the usage of the HAND model is mainly for rapid and preliminary fluvial flood hazard mapping due to lower data and computational requirements in comparison to hydraulic models.

Multibeam surveys can provide detailed bathymetry data for the continental slope from which quantitative descriptors of the seabed terrain (e.g., slope) may be obtained. We illustrate the value of these descriptors for benthic habitat mapping, and highlight the advantages of multiscale analysis. We examine the application of these descriptors as predictor variables for species distribution models, which are particularly valuable in the deep sea where opportunities to directly survey the benthic fauna remain limited. Our initial models are encouraging and suggest that wider adoption of these methods may assist the delivery of ecologically relevant information to marine resource managers.

Heterodera schachtii is managed by rotation with non-hosts, resistant cover crops, and resistant and tolerant sugar beet cultivars. Microplots 60 cm deep and 30 cm in diameter containing steamed field soil were (i) noninfested or infested with 550 H. schachtii eggs per 100 g at (ii) 0 to 60 cm, (iii) 0 to 30 cm or (iv) 30 to 60 cm in depth. Plots were planted to susceptible, resistant, and tolerant sugar beets. Five weeks later, the sugar beet canopy was largest in condition i, smallest in condition ii, and intermediate in conditions iii and iv. White sugar yield (WSY) was highest in condition i, second in condition iv, lowest in condition ii, and intermediate in condition iii. Cultivar-specific final nematode numbers were independent of the level of infestation. In two experiments utilizing 1-m2 microplots, naturally occurring H. schachtii populations were suppressed with fosthiazate at depth layers in reverse to those infested in the first experiment, and planted to susceptible, r...

The curvature of the terrestrial surface enters into the category of primary parameters, directly derived, on the strenght of the altimetric values stored up in the grid type elevation structures. Geomorphological, it indicates the changing rate of the slope or of the orientation per unit lenght, in the XY plan. There are many types of curvatures, but in the more important morphometric analyses they are the following: profile curvature, plan curvature, tangential curvature, longitudinal curvature, transverse curvature, maximum curvature, minimum curvature, medial curvature, general curvature. This article aims at highlighting the differentiations that appear in the qualitative interpretation, in a geomorphologic sense, the results of the processing curvatures’ varieties in a series of GIS type programmes. At the same time, we had as our goal, the identification of the causes for these interpretative disparities, causes that are found in the mathematical apparatus used at the elabora...

In this paper, a high-resolution digital elevation model (DEM) of the Ischia Island has been created, and a digital terrain analysis has been carried out to identify of morphostructural elements of this landscape. Ischia is an active volcano located in the Western sector of the Gulf of Naples that is characterized by historical and recent volcano-tectonic activity. The local kinematics is unclear, and so identification of tectonic lineaments might elucidate recent tectonic processes. We identify morphostructural features using geomorphic parameters derived from analysis of the high-resolution DEM. Successively, the comparison with known geologic features provides validation of the extracted morphotectonic data. We found that one of the main directions of the morphostructural lineaments extracted is consistent with the regional NE-SW extensional stress field; moreover, the lineaments on the northern flank of Mt. Epomeo are strictly correlated with the mapped faults that have a history of strong and moderate earthquakes. The technique implemented for this study area allowed us to identify new original morphostructural lineaments in a reproducible way that may be useful for investigating various landscapes where field survey is not possible. Indeed, the extracted lineaments represent potential active faults near the northern coast of the Ischia Island, where both seismicity and intense urbanization delineate a high seismic risk.

Applications of remote sensing and CIS for groundwater modelling of large semiarid areas 187 200 I 400 Ktlometers Lake Chad Basin Lake Chad Basin Rivers Quaternary aquiIer Country political boundaries Regions selected Ior Iig. 2 Fig. 1 Location of the Lake Chad Basin ...

The oldest materials in the region appear to be radar dark plains with light mottling in places. These plains are cut by fractures and other tectonic features, as well as at least one sinuous channel that may be the result of lava erosion. Superimposed on these plains and the associated structural features is a 75 krn diameter impact crater which in turn has been buried by lavas erupted from the Mylitta Fluctus source area. This volcanic complex is associated with the massive lava flow field that extends northwards into Lavinia Planitia for some 800 km. Superimposed on the source area are numerous small shields of a few kilometres in diameter.

The oldest materials in the region appear to be radar dark plains with light mottling in places. These plains are cut by fractures and other tectonic features, as well as at least one sinuous channel that may be the result of lava erosion. Superimposed on these plains and the associated structural features is a 75 krn diameter impact crater which in turn has been buried by lavas erupted from the Mylitta Fluctus source area. This volcanic complex is associated with the massive lava flow field that extends northwards into Lavinia Planitia for some 800 km. Superimposed on the source area are numerous small shields of a few kilometres in diameter.

A region-by-region condensed description of almost all of the area that was radar-photographed by Veneras 15 and 16 is presented. Using some generalizations, the diversity of terrain was reduced to a discrete set from which a geological-morphological map was constructed. The predominant type of terrain of the studied area is a plain that was tentatively subdivided into five morphological types: ridge-and-band, patchy rolling plain, dome-and-butte plain, smooth plain, and high smooth plain. Stratigraphically, the ridge-and-band plains are the oldest and the smooth plains are the youngest. The stratigraphic position of the other types is yet to be determined. Large sections of the plains show similarities to the mare-type basaltic plains of the moon, Mercury, and Mars. Other types of terrain are combinations of ridges and grooves in various patterns: linear parallel, orthogonal, diagonal or chevron-like, and chaotic. In some places the ridge-and-groove terrain is stratigraphically below the plain material, but in other places it appears to be plain material that has been subsequently deformed. Near the eastern and western boundaries of Ishtar Terra large (several hundred kilometers in diameter) ring-like features can be seen that are named coronae or ovoids. Evidence of tectonic deformation and the presence of flow-like patterns support their designation as volcano-tectonic features. Beta Regio seems to be an uplifted plain showing evidence of rifting and volcanism. All types of terrain are sparesely peppered with craters of obvious impact morphology. Their average density gives the plain an age range of 0,5 to 1 × 10 9 years. The fact that many impact craters are still in the pristine state indicates a very low rate of surface reworking, at least for the last 0,5 to 1 × 10 9 years. No evidence for water-erosion-sedimentation processes has been found. The tectonic activity of Venus has no equivalent on the moon, Mercury, or even Mars, and can be The Geology and Geomorphology of the Venus Surface 161 compared only with that of the Earth. Intensive horizontal deformation, previously known only on Earth, occurs on Venus, but in a characteristic Venusian style.

This study uses a Geographical Information System (GIS) for terrain analysis of the Keller Peninsula (KP), King George Island (KGI), Antarctica, to describe its morphological characteristics. We processed a vertical metric aerial photography and a Digital Terrain Model (DTM) in a Digital Photogrammetric Station to generate an orthophoto and then to create a KP orthophotomap. A more detailed DTM for the area surrounding the Brazilian Comandante Ferraz Station (EACF) was generated adding local points with known elevation. From these DTMs, we derived hypsometric, slope and aspect maps, hillshade models, perspective view scenes and topographic profiles, as well as measurements of distances, perimeters, areas and volumes for the KP and the EACF areas. At KP predominate steep terrain slopes (35.6%), followed by very steep (22.3%), moderate (20%) and abrupt areas (12.8%). Its hillsides are mainly westward (21.3%) and eastward (15.3%) oriented.

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Water is strategic but also highly vulnerable natural resource, this because the increasing demand from multiple uses, in many cases competing amongst them, seems to influence the concepts of sustainability of the exploitation of the water resource. In this context, mathematical models were developed to support the decision process (DSS), in order to evaluate and manage the available superficial water resource. The approach of this models is focused towards a natural integration of the two processes of evaluation and management of the available water resource, in an operating context, that is shared amongst managers, users and the local administration concerned. These results can be achieved by means of the new technologies in the field of elaboration, representation, communication and sharing data, this means to combine the potentialities of the Web with those of GIS systems (Web-GIS). The application of the methodology briefly introduced was applied to the Tiber River basin, and h...

Worldwide, landslides claim many lives each year, with an average of 162.6 deaths reported in Japan from 1945 to 2019. There is growing concern about a potential increase in this number due to climate change. The primary source of shallow and rapid landslides within watersheds is the 0-order basins, which are located above the 1st order drainage system. These active geomorpho-logical locations govern the frequency of mass movement. Despite the recognition of their im-portance, little attention has been paid to the role of 0-order basins in initiating landslides. Drainage systems can be extracted using the Digital Elevation Model (DEM) in GIS software. However, the effect of DEM resolution on the extraction of 1st order basins remains unexplained. This research develops an algorithm to assess the impact of DEM resolution on the extraction of first-order basins, channel head points, and the identification of approximate zero-order basins. The study includes algorithms to evaluate the correlation between DEM resolution and 1st order drainage system ex-traction using fuzzy classification techniques for approximate 0-order basins. The algorithm was applied in Toho Village, Fukuoka, Japan, defining the most appropriate DEM and stream definition threshold with an 86.48% accuracy and ±30 m error margin for channel head points. Critical slip surfaces were identified inside the 0-order basins and validated with a landslide inventory map with a 91% accuracy. The developed algorithms support hazard management and land use planning, providing valuable tools for sustainable development.

Drone-based surveys offer significant advantages in terms of efficiency and accessibility, yet they are often hampered by inaccuracies in distance measurements. These inaccuracies arise due to factors such as uneven terrain affecting ground-based drones and altitude fluctuations impacting aerial drones. This paper explores these challenges and introduces an innovative solution: the use of dual-drone laser technology to enhance measurement precision. By employing two drones-either ground-based or aerial-equipped with laser transmitters and receivers, we can mitigate the errors caused by terrain irregularities and altitude variations. Our findings suggest that this approach significantly improves the accuracy of distance measurements compared to traditional single-drone methods, offering a more reliable alternative for various surveying applications. Introduction: In recent years, drone technology has emerged as a transformative tool in the field of surveying, offering unprecedented access to remote and challenging environments. Drones provide a versatile platform for collecting high-resolution data across vast areas with remarkable speed and efficiency, significantly reducing the time and labor traditionally required for such tasks. The ability to capture aerial imagery, topographic data, and other critical information has made drones indispensable in a variety of industries, including agriculture, construction, environmental monitoring, and disaster management.

The complex development of geomorphometric theory has led to various concepts of land surface curvature (LSC), whose compatibility has not yet been systematically investigated. The definition, terminology and interpretation of LSCs show significant confusion and gaps reflected in various applications in geoscience modelling and prediction. Here we discuss the present situation, specify basic problems, and make initial suggestions for their solution.

— Landslide is routine geological process on earth’s crust, but recorded under disasters due to loss of lives and property. Prevention and mitigation of disaster can be planned if detected prior to the occurrence. The proposed paper is detection and mapping tool of probable mass movements and its destruction potential. The area surrounded by pre occurred landslide at Bhilar in Maharashtra is chosen for the present study. The effort has been made to study the Geo-informatics approach containing Remote sensing data and GIS as software integrated tool towards Landslide Hazard zonation. The various Spectral signatures and the image interpretation keys with respect to slope instability and various image data to identify Pre-occurred events and vulnerable sites are studied and used. The multivariate statistical analysis in the form of Information value method has been implemented along with the spatial analysis to obtain Landslide Susceptibility and Hazard Zonation. The methodology consid...

Mapping and analysis of alluvial gold concentrations as well as assessment of the impact of mining activities on the people of Talensi-Nabdam District, Ghana was undertaken. The mining concessions allocated to small-scale miners were surveyed and mapped using Total Station and Electrometric distance measurement equipment. Forty concessions were investigated: the largest covered 28.3ha. Analysis of ore bodies and slope percentage shows that Manganiferous Rock has the highest percentage rate of occupancy (46.5 %) with a slope percentage rate of 0-90%. Sandstone follows with 26.8% rate of occupancy and a slope rate of 0-100%. Sandstone and Quartz field-Spar Porphyry have the highest slope rate within 0-100%. Predictive terrain analysis indicated that the concentrations of the deposits are geographically located within the North-East and South East regions of the study area. Gold production evaluation shows that maximum increament was experieced in the year 2001 with a production unit o...

This study examines the relationship between wetlands hidden beneath the forest canopy (‘cryptic wetlands’) and dissolved organic carbon (DOC) export to streams and lakes in forested ecosystems. In the Turkey Lakes Watershed (TLW), located in the Algoma Highlands of central Ontario, Canada, there is substantial natural variation in average annual DOC export (kgC ha−1 year−1), ranging from 11·4 to 31·5 kgC ha−1 year−1 in catchments with no apparent wetlands. We hypothesized that the natural variation in DOC export was related to cryptic wetlands. Cryptic wetlands were derived manually from geographic coordinates that were surveyed with a differential global positioning system, and automatically from identification of topographic depressions and flat slopes (<1·5° ) within a digital elevation model (DEM) in a geographic information system. For the TLW catchments, which are characterized by shallow soils over bedrock, a significant correlation (r2 ≥ 0·9, p < 0·001) between manual...

This study presents a simple model of dissolved organic carbon (DOC) loading to surface waters that is applicable to headwater catchments in forested regions on glaciated landscapes. Average annual DOC export was highly variable among the 33 experimental catchments along an east‐west transect, ranging from 0.90 to 13.74 g C/m2/a. It was hypothesized that the proportion of wetlands within the catchments would explain the majority of variation in average annual DOC export. To test this hypothesis, digital terrain analysis was used to derive wetlands automatically under both open and closed forest canopies by identifying the probability of a grid cell being a depression and/or flat. Using a 10 m digital elevation model (DEM) derived from readily available sources, the proportion of wetlands explained 63% of the variance in average annual DOC export among the 33 experimental catchments. Inclusion of regional climatic indicators, including the number of growing degree days (with a base o...

This work presents a methodology for the refinement of shuttle radar topographic mission (SRTM-90 m) data available for South America to enable detailed watershed studies in Amazonia. The original data were pre-processed to properly map detailed low-order drainage features and allowed digital estimates of morphometric variables. Spatial-resolution refinement (3 00 to 1 00 , or $90 to $30 m) through data kriging was found to be an interesting solution to construct digital elevation models (DEMs) with more adequate presentation of landforms than the original data. The refinement of spatial resolution by kriging interpolation overcame the main constraints for drainage modeling with original SRTM-90 m, such as spatial randomness, artifacts and unrealistic presentation due to pixel size. Kriging with a Gaussian semivariogram model caused a smoothing of the resulting DEM, but the main features for drainage modeling were preserved. Canopy effects on the modeled surface represented the main remaining limitation for terrain analysis after pre-processing. Data regarding a small watershed in Amazonas ($38 km 2), Brazil, were evaluated through visualization techniques, morphometric analyses and plot diagrams of the results. The data showed limitations for use in the original form, but could be applied for watershed modeling at relatively detailed scales after the described pre-processing.

We first provide a critical review of statistical procedures employed in the literature for testing uncertainty in digital terrain analysis, then focus on several aspects of spatial autocorrelation that have been neglected in the analysis of gridded elevation data. When applied to first derivatives of elevation such as topographic slope, a spatial approach using Moran’s I and the LISA (Local Indicator of Spatial Association) allows: (1) georeferenced data patterns to be generated; (2) error hot- and coldspots to be located; and (3) error propagation during DEM manipulation to be evaluated. In a worked example focusing on the Wasatch mountain front, Utah, we analyse the relative advantages of six DEMs resulting from different acquisition modes (airborne, optical, radar, or composite): the LiDAR (2 m), CODEM (5 m), NED10 (10 m), ASTER DEM (15 m) and GDEM (30 m), and SRTM (90 m). The example shows that (apart from the LiDAR) the NED10, which is generated from composite data sources, is...

Ahnert Ahnert, F., 1970. Functional relationships between denudation, relief and uplift in large mid-latitude drainage x basins. Am. J. Sci. 268, 243-263 proposed that a denudation rate D could be predicted by the relation D s 0.1535h, where h is local relief, a substitute for mean slope. The present study seeks to explore the value of this simple equation as a normative geomorphological tool. In two successive and complementary stages, its principles are applied to the Western Dharwar Craton of South India. First, the robustness of local relief as a reliable substitute for mean slope is examined. Following the demonstration that the equation can successfully be used in the region of interest pending correction factors for rock resistance, a potential denudation map of the Western Dharwar Craton is established. The pattern of potential Ž 2. denudation values is compared with known measurements of both long-term ; 10 Ma denudation rates inferred from Ž y5. apatite fission track data and modern ; 10 Ma denudation rates derived from available sediment load measurements in relevant river basins. Unexpectedly close similarities between long-term, short-term and potential denudation rates prompt a discussion on the merits of potential denudation as a possible standard in the appraisal of measured rates and as a tool for establishing permissible denudation rates when assessing the impact of man-induced erosion. A landscape-specific basal metabolic rate of erosion is defined as a new concept. The methodological pitfalls in extrapolating denudation rates from the measurement of sediment loads in rivers are reviewed and suggestions for tighter investigation are made.

Radar imagery has become one of the most important data sources and efficient tools for terrain analysis and natural resource surveys since 1960s. With the development of technology in the field of radar remote sensing, new generation of radar sensors, i.e., Synthetic Aperture Radar (SAR) was born. Unique specifications of radar systems and images versus optical ones led to a whole new series of applications for radar imageries all over the world. However, the level of achievable accuracy from radar imageries is still a problem for their applications. Multiplicative noise such as speckle which is unavoidable part of coherent radar images, degrade radiometric quality and interpretability. Moreover, geometric distortions such as foreshortening, layover, shadow and other problems related to special imaging geometry of radar systems, decrease reliability of radar imageries. Thus, radiometric and geometric corrections and calibrations must be applied to the radar images before using them...

Considering the critical importance of the quality of input data for landslide susceptibility, we investigate the performance improvements that can be achieved by different globally available digital elevation models (DEMs) using different state-of-the-art statistical and machine-learning models. For this purpose we compare the predictive performances achieved using terrain attributes derived from TanDEM-X DEM (12 m resolution and resampled to 30 m), ASTER DEM (30 m), SRTM DEM (30 m), and a DEM (25 m) interpolated from contour lines (1:25.000 map scale), exploiting the capabilities of logistic regression, generalized additive models, random forests and support vector machines. The study was conducted in the Buz au Sector of the Curvature Subcarpathians of Romania, a region highly susceptible to landslides. While the performances varied little among modelling techniques, the use of different DEMs strongly influenced the cross-validation accuracy of landslide susceptibility models. TanDEM-X (12 m) based susceptibility models outperformed models based on the other DEMs (median Area Under the Receiver Operating Characteristics Curve (AUROC) values 0.708-0.730). Models using ASTER-derived terrain attributes showed the poorest predictive capabilities (median AUROC 0.568-0.595). We conclude that the quality of DEMs is of critical importance in landslide susceptibility modelling, and greater efforts should be made to obtain suitable DEM products.

Tools for accurately predicting environmental risks, such as the location and spatial extent of potential inundation, are not widely available. A dependence on calibration and a lack of available flood data have prevented the widespread application of existing hydrodynamic methods for predicting the extent of inundation. We use the height above the nearest drainage (HAND) terrain model to develop a simple static approach for mapping the potential extent of inundation that does not depend on flood observations and extends beyond methods for mapping low-lying areas. While relying on the contour concept, the method utilizes drainage-normalized topography and flowpaths to delineate the relative vertical distances (drop) to the nearest river. The HAND-delineated relative drop is an effective distributed predictor of flood potential, which is directly related to the river stage height. We validated the new HAND contour approach using a flood event in Southern Brazil for which high-resolution maps were available. The results indicated that the flood hazard-mapping method accurately predicted the inundation extent of the channel carrying the flood wave and the channels influenced by flooding. For channels positioned outside of the flood-wave area, the method overestimated the actual flood extent. As an original static assessment of floodwaters across the landscape, the HAND contour method could be used to map flood hazards in areas with poor information and could promote the development of new methods for predicting hydrological hazards.

Moving beyond the 4th Dimension of Quantifying, Analyzing and Visualizing Acoustic Beamformed Data Chris Malzone 1 , Michael Mutschler 2 , Tim Pauly 1 , Matt Wilson 1 , Ian Higginbottom 1 1 Myriax Inc, 2877 Historic Decatur Road, San Diego California 92106 USA 2 ...

Maps showing the distribution of seabed nature types, or habitats, are an important component of regional seabed mapping, such as in Norway's 'MAREANO' programme. This is particularly the case when economic interests in the offshore area require information as a basis for sustainable development of resources. Generation of such maps represents the meeting of traditional disciplines of geology and biology, and is a process that requires multidisciplinary cooperation. Focussing on the eastern part of Tromsøflaket bank, and adjacent troughs in the southern Barents Sea, northern Norway we show how physical and biological data have been combined, with the help of multivariate statistics to produce a preliminary nature-type map for the area. This preliminary map represents an important first step in nature-type mapping in the offshore area and contributes to the national effort to define nature types and develop methods for their mapping and prediction.

Eight landscape types have been defined and spatially documented from a 40 000 km 2 large area off Lofoten, Vesterålen and Senja in northern Norway. The area represents some of the most geologically diverse coast and offshore margin areas in Norway. The basis for the classification is an integrated, hierarchical system for terrestrial, coastal and marine nature types, presently being developed in Norway. This is the first broad-scale attempt to apply the new system in the marine domain. Detailed multibeam bathymetric data form the basis for 3D models of the seafloor, which have also been analysed using modelling and GIS tools.

Numerical algorithms are presented to estimate the length, width and slope of rectangular planes representing irregularly shaped overland contributing areas defined on raster Digital Elevation Models (DEM). The strength of the procedure lies in that each flow path on the raster overland area is considered in the determination of the representative value for the entire rectangular plane as opposed to relying on a lumped, single flow path approach. The flow path parameters required by the algorithms are derived from raster maps of elevation (DEM) , flow direction

Numerical algorithms are presented to estimate the length, width and slope of rectangular planes representing irregularly shaped overland contributing areas defined on raster Digital Elevation Models (DEM). The strength of the procedure lies in that each flow path on the raster overland area is considered in the determination of the representative value for the entire rectangular plane as opposed to relying on a lumped, single flow path approach. The flow path parameters required by the algorithms are derived from raster maps of elevation (DEM) , flow direction

SOC (Soil Organic Carbon) is one of the most important parameters affecting the hydraulic characteristics of natural soils. Despite being rather easy to measure, SOC is known to be highly variable in space. In this work we used vegetation, climate, and morphology factors to reproduce the spatial distribution of soil organic carbon (SOC) in the mineral horizons of forest and grassland areas (in NorthWestern Italy) and evaluated the feasibility of the approach. When the overall sample was analysed (114 samples), annual precipitation and elevation were significant descriptors of the SOC variability. However, a large part of the variability remains unexplained. Two stratification criteria were then adopted, based on vegetation and topographic properties. We obtained an improvement of the quality of the estimates, particularly for grasslands and forests in the absence of local curvatures. These results indicate that the spatial variability of soil organic matter is scarcely reproducible at the regional scale, unless an a-priori reduction of the heterogeneity is applied. A discussion on the feasibility of applying stratification criteria to deal with heterogeneous samples closes the paper.

High slope angles bring more stress on the surface, creating movement that can lead to a landslide. Nyabihu district is one of Rwanda district which has high slope, high steepness and the topographical parameters area that is the main causes of landslides on community livelihood. The steep terrain and heavy rainfall patterns of the region exacerbate soil erosion and slope instability, leading to frequent landslides that endanger lives, disrupt communities, and damage critical infrastructure. Spatial datasets collected is Landsat imagery were downloaded from USGS website, which was used to analyze the land use land cover of the study area, Digital Elevation Model (DEM) data of 12.5 cm spatial resolutions were also downloaded from Alaska Satellite Facilities vertex (ASFV) used to analyze the slope, elevation and drainage density of study area and aspect analyzed by dem with helps identify slopes aspect that are more susceptible to landslides based on factors such as solar radiation exposure, soil moisture retention, and vegetation distribution is involves identifying landslide locations. By generating a Curvature map, you can identify areas with high positive or negative curvature, which may indicate potential landslide-prone zones. Rainfall data were obtained from Worldclimate.organd and soil types data from Rwanda Geoportal, soil moisture retention, and vegetation distribution is involves identifying landslide locations and proximity to roads network was used to identify distance to road vulnerability from landslides, calculating their spatial relationship, and assessing the vulnerability of landslide hazards respectively was also use as causative factors was rainfall,slope,elevation,aspect,lulc and proximity to road network to landslide in the study area. This research demonstrated how GIS tools can be used to produce map of landslide vulnerable areas using MCA and GIS. rainfall, Slope, soil types, elevation, drainage density and LULC taken as the causative factors for landslide in Western region. The finds of this map of landslide cover indicates that very high class covered 2.54 %, medium class covered 47.57 %, low class covered 0.12 % and high class covered 49.77 % of the total area. It is recommended that both local authorities and communities in the district pay much attention to the local land use planning rules, and policies governing settlement patterns and human activities distribution in order to keep people and their households away from landslide susceptible areas. In doing so, it directly contributes to reduction of soil erosion and vegetative cover removal, thereby helping in the stabilization of the slopes.

Automated terrain analysis is required for many practical applications, such as outdoor navigation, image exploitation, remote sensing, reconnaissance and surveillance. In this paper, we present a hierarchical approach to analyze multispectral (MS) imagery for autonomous land vehicle navigation. The approach integrates several strategies to label various terrain classes in these images acquired using twelve spectral bands in the visible and near-infrared spectrum. At the low (pixel) level, it combines texture gradient results from specifically selected channels by varying the size of gradient operators and performing multithresholding and relaxation-based edge linking operations to obtain robust closed region boundaries. At the high (symbolic) level, it makes use of the spectral, locational, and relational constraints among regions to achieve accurate terrain image interpretation. Details of the technique with examples from real imagery collected by an autonomous land vehicle (ALV) are presented.

A oped for terrain analysis problem solving. The working memory of the production system is used to store specific domain knowledge about landforms. This involved the description of landforms in terms of their pattern elements, including their likelihood of occurrence. The production memory was used to store the rules of inferencing. These rules were general rules and were applicable to all landforms. Thus, the domain knowledge about terrain analysis was separated into t y o components: one component consisting of specific knowledge about landforms, stored as facts in the working memory; and the other component consisting of the general methodology for inferencing, stored as rules in the production memory. Such a separation of knowledge enables additions to the knowledge base fairly easily. The knowledge base can be extended to encompass more landforms simply by creating more working-memory elements. The present version of the prototype expert system has been implemented using OPSS, a production system language. Uncertainty calculations were performed by invoking LISP functions from O P S~. The results indicated that the production system model was appropriate for designing the prototype expert system for terrain analysis.

El-Gendi Fortress is a unique geo-archaeological site in Sinai, Egypt. It reflects the progress of the Islamic military architecture during Saladin’s reign (Salah ad-din al Ayyubi), the founder of the Ayyubid dynasty (1174-1260AD). The fortress's location met two major geo-criteria. One is geographical; it is located on a mound 655 m above sea level (a.s.l) and 152 m above El-Tih El-plateau; this elevation contributes to the exploration of the surrounding areas and provides the fortress with a strong defensive position against the Crusaders' invasions of Egypt (1163–1169 AD). The second is Hydro-geological; it provides exceptional access to both meteoric surface (via barrages) and groundwater (through Sudr spring). The latter is from deep aquifers of the Nubian sandstones (Malha Formation) across the fractured carbonates (Raha and Sudr Formations of Cenomanian to Maastrichtian age). Such water was accumulated since the Pleistocene pluvial age until the fortress’ most recent ...

Spatial variability of soil hydraulic properties was measured in a forested hillslope and analyzed by applying combined water-retention-hydraulic-conductivity models (the LN and VG models) and a power function model for soil hydraulic conductivity (the Leibenzon model). Results showed that the pore-tortuosity parameterl in the LN and VG models should be treated as a fitted parameter for accurate descriptions of the unsaturated conductivity. The simultaneous optimization of both retention and conductivity curves is preferable to obtain appropriate descriptions of hydraulic properties when both retention and conductivity data are available for the parameter estimation. The Leibenzon model produced slightly poorer estimates than the LN and VG models. The exponent parameter in the Leibenzon model exhibited a spatial variation with the standard deviation of 2.38. The spatial variability of hydraulic properties was analyzed based on the spatial variation in parameters of the LN model obtained by the simultaneous optimization procedure. The parameter ψ m , which has a positive correlation with median pore-radius, was generally small at the crest and upper slope locations and large at mid-slope to footslope locations. Except for the crest, surface soils had larger ψ m values than the subsurface soils, suggesting a well-developed crumb structure in surface horizons of forest soils. For most soils, σ was greater than I, indicating a relatively large width of pore-size distribution. Saturated hydraulic conductivity (K s) was generally small at crest and upper slope locations, and large at mid-slope to footslope locations. The largerK s values were attributable to largerψ m values.

The proximity relations inherent in triangulations of geometric data can be exploited in the implementation of nearest-neighbour search procedures. This is relevant to applications such as terrain analysis, cartography and robotics, in which triangulations may be used to model the spatial data. Here we describe neighbourhood search procedures within constrained Delaunay triangulations of the vertices of linear objects, for the queries of nearest object to an object and the nearest object to an arbitrary point. The procedures search locally from object edges, or from a query point, to build triangulated regions that extend from the source edge or point by a distance at least equal to that to its nearest neighbouring feature. Several geographical datasets have been used to evaluate the procedures experimentally. Average numbers of edge-edge distance calculations to find the nearest line feature edge disjoint to another line feature edge ranged between 15 and 39 for the different datasets examined, while the average numbers of point-edge distance calculations to determine the nearest edge to an arbitrary point ranged between 7 and 35.