Terrain Units Research Articles

Visual interpretation of landsat-1 imagery of central and southern districts of Haryana state, India

LANDSAT-MSS data in the form of a false colour composite image at a scale of 1:250,000 has been used to produce terrain unit maps of parts of north west India. The area of study consisted of central and southern districts of Haryana State.

Terrain Evaluation of the Dempster Highway across the Eagle Plain and along the Richardson Mountains, Yukon Territory

A detailed terrain classification was carried out as part of a study on the Dempster Highway from Mile 166 to Mile 290.5, the Yukon–Northwest Territories Border. The objective was to establish a rational basis for field testing and subsurface exploration programs in the future and the evaluation of the potential effects upon the physical environment of the construction of highways and other transportation facilities in the Arctic, on terrain composed of sedimentary rocks which have not been glaciated. Terrain units were established on the basis of geology, vegetation, topography, and patterned ground. The subsurface sediments were mapped mainly as outcrops of weathered shale and sandstone. The sandstone was found to be the most stable foundation and borrow material. The shale was found to be mainly clay with high ice contents near the surface, and was observed to be very unstable when thawed. A number of plant communities, which differed significantly from a geotechnical point of view, were identified.

Terrain units in eastern Antarctica

APPROXIMATELY 12,000,000 km2 of bedrock in Antarctica is inaccessible, except to remote sensing, beneath an ice sheet up to 4.5 km thick. The topographical and geological pattern of the subglacial continent has, consequently, been little investigated and no more than a few geophysical measurements have been obtained. The availability of continuous records of bedrock topography from airborne radio echo sounding, however, now facilitates the calculation of statistics of terrain roughness, which can be used quantitatively to differentiate subglacial regions, to cluster similar units, and to indicate associations or characteristics related to geological factors1.

Soils and Terrain Units Around Resolute, Cornwallis Island

The soils around Resolute, southwest Cornwallis Island, are mapped and described. Polar Desert, Lithosol and Tundra gley are identified as the main genetic soils. Polar Desert Soils and Lithosols are found on dry, moisture-shedding sites, whereas some Bog soils are intermixed with Tundra gleys in wet, poorly drained and plant colonized sites. Subdivisions of soil series are associated with terrain units, which are regarded as a useful differentiating basis among arctic soils and as an aid in their mapping. Local variation within the three genetic soils is related to changes in parent material, terrain unit and percent plant cover. Weathering and pedogenesis are those of a cold, arid environment, and the Polar Desert soils are dominant in the study area.

SYSTEMATIC AERIAL PHOTO ANALYSIS OF SOFT GROUND CONDITIONS

In such a mountainous country as Japan, alluvial lowlands are basically important for human activities, and are most densely populated. As the occupance of the earth's surface by man-made structures is essential for human activities, ground conditions of lowland areas should be considered the significant natural environment. Ground conditions are also closely related with human activities as causative factors which result in natural disasters such as ground subsidenc and earthquake damage. Almost all problems due to ground conditions which affect land use, land development and disaster prevention have resulted in the areas with soft ground conditions, as evidenced in such industrial cities situated on coastal deltaic lowlands as Tokyo, Osaka, Nagoya and Niigata, and in many other poorly-drained lowlying lowlands throughout Japan where rapid regional development is now in progress. Ground conditions have mainly been studied by soil engineers and engineering seismologists to the present in Japan. Considering the significance of ground conditions as environment, their formations, areal differences and influences to human activities must be the subjects of physical geographical study. Numerous studies on photo analysis and interpretation in geology and soils have been conducted by many specialists, but no systematic study on ground conditions has been made in Japan or in other countries. The first purpose of this paper is the presentation of the methods and techniques used to analyze ground conditions, above all soft ground conditions by aerial photographs. The second purpose is the contribution of the methods and techniques to engineering soil survey and regional planning from the viewpoint of disaster prevention. The main tool of aerial photo analysis and interpretation used in this study is a systematic analysis of micro-landforms supported by the know-ledge of geomorphological development. Geology and soils comprising ground conditions cannot be seen directly on aerial photographs. The main keys for interpreting geology and soils are micro-features of the earth's surface and tonal characteristics. But, the analysis of tonality is handicapped in alluvial lowlands of Japan because of intensive land utilization, and the systematic analysis of micro-landforms plays the most important role. Micro-landforms seen on lowlands can be regarded as a record of a recent episode of geomorphological development and the surface expression of sedimentary materials deposited by various agents. In other words, it may be said that micro-landforms of lowlands are the most significant indicator showing the distribution of geologic materials. Hence, the delineation of the terrain units composed of a single kind of geologic materials depending on the similarlity and homogeneity of micro-features, and the correlation of those units with engineering soils are the essential processes for determining ground conditions from the air. The first step to infer ground conditions is the delineation of “micro-landform units”, which are the smallest land units and are composed of similar geologic materials having similar physical properties. The standard micro-landform units which are used to interpret engineering soils in alluvial lowlands of Japan are presented in Table 1. Classification of micro-landform units is based on genetic classification of landforms. These units are suited for delineating the areal extent of soft ground areas. However, geologic materials or soils inferred directly from such units are generally limited to those forming near the surface of the ground.

Terrain Analysis for Metropolitan Fringe Area Planning

A method for mapping the physical characteristics of land, and for applying this information to an evaluation of the suitability of the land in metropolitan fringe areas to urban development is presented. It is proposed that land use suitability maps be prepared for planning areas. These maps indicate the relative land use suitability of terrain units in the planning area by rating these units as optimum, satisfactory, marginal, or unsatisfactory for various land uses. The land use suitability maps are based on terrain maps drawn for the area and on land use suitability ratings prepared for the area. The land use suitability ratings are based primarily on the topography, soil, drainage, and depth to bedrock characteristics of land areas. Land use suitability maps should be used as a planning tool in conjunction with an evaluation of the other social, economic, political, and environmental factors that shape the patterns of urban development.

Airglow of Venus: a re-examination

Rhea is the second largest icy satellites of Saturn and it is mainly composed of water ice. Its surface is characterized by a leading hemisphere slightly brighter than the trailing side. The main goal of this work is to identify homogeneous compositional units on Rhea by applying the Spectral Angle Mapper (SAM) classification technique to Rhea’s hyperspectral images acquired by the Visual and Infrared Mapping Spectrometer (VIMS) onboard the Cassini Orbiter in the infrared range (0.88–5.12 μm). The first step of the classification is dedicated to the identification of Rhea’s spectral endmembers by applying the k-means unsupervised clustering technique to four hyperspectral images representative of a limited portion of the surface, imaged at relatively high spatial resolution. We then identified eight spectral endmembers, corresponding to as many terrain units, which mostly distinguish for water ice abundance and ice grain size. In the second step, endmembers are used as reference spectra in SAM classification method to achieve a comprehensive classification of the entire surface. From our analysis of the infrared spectra returned by VIMS, it clearly emerges that Rhea’ surface units shows differences in terms of water ice bands depths, average ice grain size, and concentration of contaminants, particularly CO2 and hydrocarbons. The spectral units that classify optically dark terrains are those showing suppressed water ice bands, a finer ice grain size and a higher concentration of carbon dioxide. Conversely, spectral units labeling brighter regions have deeper water ice absorption bands, higher albedo and a smaller concentration of contaminants. All these variations reflect surface’s morphological and geological structures. Finally, we performed a comparison between Rhea and Dione, to highlight different magnitudes of space weathering effects in the icy satellites as a function of the distance from Saturn.