University of Idaho School of Forestry - Forester Yearbook (Moscow, ID)

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THE IDAHO FORESTER 41 Th-e form of the information lends flexibility to it and its completeness instills confidence by removing uncertainties. Group decision and the elimination of the personal equation will tend to strengthen judgment and are a natural outcome of aerial examination and surveys. DIVERSITY OF USE The diversity of use of aerial photographs and mosaics, particularly when made under government or public auspices, enhances their economic value and conversely reduces the ultimate cost, as the information is applicable to many purposes. Aerial photographs and mosaics embody the possibility of being de- veloped into topographic maps. In addition they depict a replica of every ground feature and can be used for all purposes, including forestry, agriculture, reclamation, and state and government highways projects. This adaptability enhances very materially the value of the resulting information by eliminat- ing duplication of effort. Ground survey maps would indicate and emphasize only the fea- tures or subjects directly applying to the par- ticular purpose under consideration. NONTECHNICAL In many cases it is essential that certain technical aspects of projects be discussed with and made clear to nontechnical persons, for purpose of financing and appropriations. To many of these persons maps, profiles, and dia- grams are not readily comprehensible. A pic- ture or a mosaic with the project indicated up- on it brings ready comprehension and when supplemented with oblique pictures, affords understanding and eliminates long complicated explanations. A common ground of under- standing is thus provided and any tendency to- ward an individual uncertainty is removed, to the end that negotiations can proceed with more assurance and confidence in both the project and the representative. The preceding general statements introduce a few engineering aspects of aerial surveys and some of the resulting advantages. The scale of the pictures and the extent of the de- tail depend only upon the height from which the picture was taken and the extent of it is later enlargement. The map scale will vary similarly. GENERAL COMPARISON A comparison of relative values between ground and aerial examination, particularly on preliminary Work, is not readily present- able with brevity inasmuch as the aerial method introduces new elements of great val- ue that are not obtainable by ground methods. A dollar for dollar comparison is not equit- able as the advantage of the a-erial method in providing a quicker and broader understand- ing of the entire situation is infinitely gI'eater than the ground method. Similar results might be obtained by either method by the same in- dividual provided he covered the country on the ground with a thoroughness equal to the plane in the air, took enough time, and made a decision that his superiors would approve if they had seen everything that he had seen. This is a rather heavily qualified statement and the result of that procedure would be to again become subservient to the personal equa- tion and delete all of the fundamental advan- tages and assurances previously enumerated. The sole advantage would be that the man had been upon the ground and would be in a better position to classify the material. Upon returning from a reconnaissance, he would bring no corroborative evidence to support his opinion. Upon the return of the plane, a series of photographs of each route considered would be available for d-etailed study and con- sideration and would constitute a permanent record available at any time for any purpose affecting the area covered. For an explora- tory flight as compared to a ground trip, the flight would cost the least. For a photographic flight as compared to a ground trip on trails, the cost would be about the same, as the ground trip would require much more travel to gain the sam-e understand- ing and assurance. In certain very difficult areas, the ground reconnaissance would cost A Forest Survey Party Makes Use of Pack Horses to Ca.r1'y Men and E'qnfipment into Inaccessible Regions Where There Are No Roads and Often Few Trails.

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A GENERAL COMPARISON OF AERIAL AND GROUND SURVEYS THROUGH FOREST AREAS J. A. CHAMBERLIN E'I'Lg'i'l'L66'1 , Idaho Department of Public Wo1'ks THE survey through the forest for the crossing of the Bitter Root Mountains by the Lewis and Clark Highway between Lewis- ton, Idaho and Missoula, Montana was under- taken by aerial methods in the interest of speed, economy, and improved survey methods. The project was undertaken jointly by the United States Bureau of Public Roads and the Idaho Department of Public Works. A discussion of the general conclusions reached in comparison with those usually se- cured by the customary ground methods is of interest, as many new and essential advan- tages have become apparent. These advan- tages are individual to aerial methods, so constitute aerial method assets, and are enumerated rather than compared, as there are no ground method equivalents to set against them. GROUND LIMITATIONS Ground survey methods have remained prac- tically constant as to time, cost, and scope for a long period. The speed of construction ac- celerates annually. Nature's obstacles and hu- man endurance have remained constant. Man's chief limitation has been his natural means of locomotion and his limited horizontal vision. Aerial methods provide another dimension and will lift him above these limitations. The necessity for greater dispatch in con- structive decision to supplement the increasing speed in transportation and communication is well recognized. The planning and prepara- tion for constructive undertakings usually consumes more time than the construction it- self. If constructive decision and design are not accelerated in proportion to that of the other elements, the cycle of speed and time saving will not be complete. The slower functions will nullify, to a large extent, the general advance. The net saving in time will be reduced and de- velopment be retarded in a general economic sense. TIME FACTOR The time factor carries an economic and political value that is not readily determinate in dollars and cents when monetary first costs are considered and compared. It is, however, a dominant factor when measured in terms of final value received. The holding of projects in suspense during long periods of investiga- tion and ground survey is a liability on public projects and a financial loss to operating com- panies. Rapidity of decision allows the stream of development to flow continuously and re- moves obstructions that delay not only the pri- mary project, but related ones as well. The public or business interest which sup- ports the particular undertaking is continually sustained by rapidity of decision. Interest is not allowed to subside through long prepara- tory periods during which adverse conditions may arise and administrations change. During the preliminary period of considera- tion, the economic foundation of an undertak- ing is laid, as the primary findings form the basis for acceptance or rejection. It is during this period that the information at hand is usually most meager and assurances are slow in developing. By the use of aerial methods, this situation is reversed. All physical and topographical information is secured with the greatest of dispatch at a time when its pos- session is most essential. Facts are immedi- ately at hand. The maximum information is available at the psychological time and not months or perhaps years later when condi- tions, opinions and persons have changed. PERSONAL EQUATION Preliminary examinations and reports are usually made by one individual whose findings are sometimes checked by the independent re- ports of another individual and on these find- ings the program is outlined. The reports and maps submitted are unavoidably colored by the competency and reactions of the individual maps and the scope of the examination refiect his opinion as to the suiiiciency of the infor- mation. This individual attitude or personal equation, has a greater effect and infiuence during the preliminary stages than at any other time. The report of the individual is considered by a superior officer who has little means of measuring its merit and sufiiciency. The present interrelation of business and departmental subdivisions is making more and more essential the necessity for joint decisions when determining upon a course of action. The situation must be considered from varied as- pects by various executives. The information wide in scope as well as finely de- must be tailed to meet the requirements. Aerial photo- graphs, mosaics and maps, when submitted to a management allow the subject to be con- sidered by all concerned. GROUP DECISION The executive heads may then reach their own individual conclusions without being sub- ject to the personal equation of any individ- ual and without the possibility of misunder- standing any supplementary verbal or written information. The final outline for action is then developed and becomes a joint or group decision in which all interested parties have participated in proportion to their jurisdiction.

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42 more than a photographic flight, but with the qualification in each case, that ground trips do not aHord the advantages previously enumerated. ' It appears, then, that up to the point of actual maps and surveys, aerial methods offer a great advantage not only in time, but in returns from the cost, and further, that there is a credit balance to carry over and apply on the cost of ground control and mapping. AERIAL RECONNAISSANCE The effectiveness of the reconnaissance and photographic flights on the Lewis and Clark project over that of ground reconnaissance was evidenced in many ways. On the Hrst flight the Bitter Root Mountains were crossed over the Lochsa River Route and recrossed over the North Fork Route. The Ridge Route lying between the above mentioned routes was observed at the same time. The flying time was three hours, over diiiicult mountain coun- try, and the distance flown, about three hun- dred miles. The main streams were in deep narrow recesses and the high ground was sharp and ragged in form. The flight was made at an elevation of from 1,000 to 5,000 feet above the ground. The highest elevation reached was 10,000 feet and in only one case did the plane descend within a few hundred feet of the ground. It was naturally supposed that the general course and relation of the routes as well as the drainage systems would show clearly, but a surprising amount of detail proved to be ascertainable at the same time. The plane was held to one side of the objective rather than immediately above it in order to permit of the ground view in perspective. STREAMS SHOW PLAINLY In the burned areas, ground details showed with a great clearness and the nature of the material was evident. On fully timbered sec- tions where the trees rose tier on tier from narrow bottoms, and the river seemed to fill the channel, the details were not so readily ascertained. In this case, judgment could be rendered only from the general steepness of the side slopes, the bald rocky spots and masses of rock that had rolled into the river. The general configuration, however, was readily observed. The heavily timbered sec- tions were not extensive in the canyons and offered little interruption. The various routes flowed by with such rapidity that the outstanding differences were presented with emphasis and comparisons were readily made. Secondary streams could, in many cases, be seen from their sources to their mouths. The side of the main rivers having the least tributary streams was easily selected. The requirements for bridges were evident. The varied characters of ground along the river bank were easily segregated. Slopes and cliffs and the main trails showed THE IDAHO FORESTER clearly, as well as fluffs of dust stirred by a plodding pack train, with which, perchance, there traveled some engineer on ground re- connaissance. The position of the pack train indicated to a certain degree the nature of the ground near the river by its occupancy or its avoidance. TREES lVlARK HIGH WATER In many cases a line of isolated trees stood at highwater line along the rivers and so showed that the area between them and the water was a bar, and not tenable. Steep sections of the main streams were in- dicated by narrow channels and white water, and slack sections by Wide channels and black water. The scars of snow slides and cloud bursts led down the slopes to fantails of debris on the river bank and bars in the stream. The entire panorama lay spread beneath in all its detail and close or distant observation was accomplished by a word to the pilot. Mountains led away on both sides and wide deflections in the courses of river and streams were seen in their true relations and in some cases invited cut-offs by the use of more ascent and descent. The top of the divide was viewed for many miles and the passes lay spread out for observation. There is slight likelihood of missing a hidden pass from the air. Out from the divide ran slopes and ridges of varied ground which told much of their texture by their form. Basins were viewed from all sides and peaks are circled with celerity. A remark to the pilot, and distant ground is quickly close by and then swept away as ,questions are answered visually. An effortless investiga- tion conducted by a seemingly detached intel- lect that requires no endurance for its trans- portation. ROUTES EASILY COMPARED FROM AIR The examination of routes lying reasonably close to main streams is comparatively simple as the actual position of the line is determinate within narrow limits. The position of a sup- ported line that may loop about is not so readily decided upon from the air as a wide area may be occupied and the elevation line can not be determined. In such cases, the ex- amination becomes more general. The con- figuration and formation of the country over which a descent is proposed, is open to con- sideration as a whole. Desirable ground for development or support is much more readily located from the air, although ground work would be required to prove its utility and co- incidence with the desired grade line. In any case, the general character of sup- porting ground on any route or routes is readily open to comparison. Aerial recon- naissance eliminates that ever present fear on ground work of overlooking something by not knowing what lies just beyond one more hill. From the air, the entire area and many miles on each side are examined in a few ef-