The Use of Aerial Photos in Engineering Planning
The planning of any engineering project requires information on land use, topography, soils, drainage, transportation, urban de­ velopment, and many other factors before actual location and design can be accomplished or field surveys undertaken. To obtain this preliminary information engineers surveyors, and planning com­ missions need maps. They need planimetric maps showing land use, or they need topographic maps having a contour interval of at least ten feet showing planimetric detail. Unfortunately, in numerous counties of Indiana and in the various cities of the state planimetric and topographic maps are seldom available or are obsolete. For example, of the 600 odd minute quadrangle sheets that are required for mapping the state of Indiana only about 130 maps were completed before January 1951 (10). Although 35 have been issued since that date, this great undertaking is still less than 30 per cent complete. Furthermore, the cost and time required to prepare by field survey methods the different types of maps would deplete available funds and in all probability prevent the construc­ tion of the improvement or delay it for a long period of time. In addition to the shortage of maps there is a shortage of engi­ neers for collecting and compiling information into maps. This shortage is especially felt by the county, city and state governments at a time when population is increasing; and, therefore, needs for water supply, sewage treatment, parking facilities, subdivision develop­ ment, highway development, traffic studies and other engineering studies are critical. Aerial photographs are a valuable source of basic map information to overcome the shortage of maps and also save time and money in numerous planning operations. It is the purpose of this paper to discuss the characteristics of aerial photographs and to explain their use in the planning phases of engineering projects. It is to be emphasized that aerial photographs will not eliminate
DRAINAGE PATTERN SIGNIFICANCE IN AIRPHOTO IDENTIFICATION OF SOILS AND BEDROCKS
THIS PAPER REPORTS THE ANALYSES OF DRAINAGE PATTERNS FOR THEIR USE IN THE IDENTIFICATION OF REGIONAL SOILS AND BEDROCKS BY MEANS OF AIRPHOTOS. THE STUDY IS ONE OF SEVERAL CONCERNING THE INTERPRETATION OF AERIAL PHOTOGRAPHS BY THE JOINT HIGHWAY RESEARCH PROJECT AT PURDUE UNIVERSITY. THE RELATIVE EASE WITH WHICH STREAM SYSTEMS CAN BE OBSERVED ON AERIAL PHOTOGRAPHS FACILITATES THE RECOGNITION OF DRAINAGE PATTERNS. IN THE NATURAL SCIENCES, IT HAS BEEN ACCEPTED FOR A LONG TIME THAT CERTAIN BASIC DRAINAGE PATTERNS SUCH AS THE DENDRITIC, TRELLIS, RADIAL, PARALLEL, ANNULAR, AND RECTANGULAR ARE ASSOCIATED WITH SPECIFIC LAND SURFACE MATERIALS. AIRPHOTO INTERPRETATION HAS REVEALED SEVERAL MODIFICATIONS OF THE BASIC DRAINAGE PATTERNS. FOR EXAMPLE, SOME OF THESE MODIFIED TYPES ARE THE RETICULAR, PHANTOM, AND LACUNATE. DRAINAGE PATTERNS, TRACED DIRECTLY FROM REPRESENTATIVE AIRPHOTOS OF VARIOUS PHYSIOGRAPHIC REGIONS THROUGHOUT THE UNITED STATES, ARE PRESENTED AS ILLUSTRATIONS OF PATTERNS WHICH DEVELOP IN THE SOILS AND BEDROCKS TYPICAL OF THE REGIONS. THESE EXAMPLES HAVE BEEN SELECTED TO SHOW NOTICEABLE DIFFERENCES IN DRAINAGE PATTERNS. FOR INSTANCE, DRAINAGE PATTERNS IN REGIONS WHERE THE ROCKS ARE BARE OR ARE COVERED ONLY WITH SHALLOW SOILS, ARE DECIDEDLY DIFFERENT THAN THOSE IN REGIONS OR DEEP GLACIAL DRIFT. LIKEWISE, DRAINAGE PATTERNS DEVELOP DIFFERENTLY IN HORIZONTAL ROCKS THAN IN TILTED ROCKS. IT IS CONCLUDED THAT SURFACE DRAINAGE PATTERNS CAN BE RELIED UPON IN THE AIRPHOTO IDENTIFICATION OF SOILS AND BEDROCKS ON A REGIONAL BASIS. /AUTHOR/
Geologic proof on paleo-glaciation remains in Laoshan Mountain
Laoshan Mountain is the highest mountain in China coast.Various typical geomorphic features of glarosion,glacial deposition,rare glacial moraine coast and glacial moraine fans in east are well developed in Laoshan Mountain.Well preserved four glacial epochs are identified in Laoshan Mountain.In early Pleistocene,the altitude of snowline ranged from 60 m to 90 m in east.More than sixty paleo-glacial tongues were developed in Laoshan Mountain,some of them which located in east extended into the Yellow Sea.Sporopollen analysis indicates that the climate in Laoshan Mountain is very cold during the ice age.Multi-modal grain-size probability curves of the moraines are the typical characteristics of sediments deposited by glaciation.Regional landforms and climatic conditions are the key factors dominating the altitude of snowline during the ice age.