Contacts
home/ Casual

What does it mean to mark the relief on the map. Reading topographic maps. Relief. Out-of-the-box design of cards

Of all the elements of the terrain, relief plays the most important role, because it affects the state and position of all other elements: hydrography, distribution settlements, roads, vegetation, etc. Between all these elements there is a certain relationship, which is influenced by the relief. Terrain is the most difficult to depict on a map because the terrain needs to be displayed in three dimensions, and the map is a flat representation of the terrain. The relief is three-dimensional in space and has a huge variety of volumetric forms that must be conveyed on a plane. Therefore, there are several ways to depict relief, which are currently used in one way or another on maps for various purposes.

1 Picture (perspective) way... In this way, the relief was depicted on old maps in the form of primitive drawings of heights, mountains, ridges. The relief was depicted as seen. For greater clarity, the mountains were covered with shadows.

It is not necessary for him to know the absolute or relative heights, the steepness of the slopes, but it is enough to convey a perspective image of the relief. Visibility and simplicity are the main advantages of the pictorial way of displaying the relief on maps, but, of course, geometric accuracy cannot be conveyed in this way.

This method of depicting relief was widespread in the 15th – 18th centuries. Currently, this method is used on those maps where clarity, rather than accuracy, is required, and therefore it is primarily used on children's maps.

2 Dash method... Paintings of the relief in the 18th century. first of all, it ceased to satisfy the military, the main consumers of cards. They had to quickly get an accurate idea of ​​the steepness of the slopes, the roughness of the terrain, and the nature of the relief in general from the maps. Therefore, a new way of depicting relief was proposed - dashed. In Russia, the A.P. Bolotov and the scale of the General Staff. The principle of constructing such scales is as follows: the steeper the slope, the thicker and denser the shading,

at the same time, steep slopes are covered with shadow, and gentle ones are highlighted.

The disadvantage of this method was that it is impossible to determine the absolute and relative heights by means of the strokes. In addition, stroke drawing is very laborious, and card printing requires high reproduction techniques. Therefore, they began to look for new ways to depict the relief. Currently, this method is used when depicting rocky relief on topographic maps.

3 Method of shading relief(black-and-white plastic), that is, the creation of a halftone image under a given illumination of the area. Hillshade is used to add dimension to relief shapes.

On handwritten maps, washing was widely used already in the second half of the 18th century, but its printing was mastered only in the middle of the 19th century. as a result of the introduction of lithography. The original hillshade is like a photograph of a relief model of the terrain with lateral northwest lighting.

In this case, all the slopes located opposite the light source remain white, the opposite slopes are dark, and those located at different angles to the light are colored with shadows of different brightness and lightness, depending on their illumination. The washing method gives a clear plastic image of the relief. The disadvantage of this method is that it is impossible to determine the steepness of slopes and heights of points on the map.

Washed is currently used on some small scale general geographical maps, but more often a light gray wash is applied in addition to horizontal lines and gypsometric painting. Today, you can find light washing of the relief on political, political-administrative and administrative maps. Shading the relief is performed using the Adobe PhotoShop program.

4 Method of spot marks. Spot elevations are the absolute elevations of points that are labeled on the map. With the help of elevation marks, they show the characteristic heights, including the command ones, which have the greatest height, from which the possibility of a good view of the terrain is realized. High-altitude marks of mountains, hills, mounds, passes, cliffs and ledges, embankments and notches are distinguished. They make it easier to read the map and make it possible to determine the excess of some points over others.

As an independent method, elevation marks are not used, since they do not give a clear and visual representation of the relief, therefore they are used in combination with other methods of depicting the relief.

5 Contour lines method... A horizontal is a line that connects the same elevation marks. Contours are the main way to represent relief on topographic maps. There are the following types of contour lines: solid (drawn according to the height of the section); thickened (at a section of 5.0 m and 20 m, every fifth horizontal line is thickened, at a section of 2.5 m - every tenth); additional horizontals or semi-horizontals (drawn at half the height of the relief section); auxiliary contours (drawn at a quarter of the height of the relief section).

The horizontal lines are supplemented with bergstrokes (short dashes perpendicular to the horizontal lines, indicating the direction of the slope), labels of the elevation marks of the characteristic points of the terrain and some contour lines (the marks are signed in their breaks and the base of the numbers is always located down the slope). The main advantage of this method is that it is possible to carry out various cartometric work along the horizontal lines: to determine the absolute heights of points and the elevations of some points over others, the steepness and direction of slopes, etc. From the drawing of the contour lines, their shape, the density of the survey, you can get an idea of ​​the terrain. Correctly selected height of the relief section on the map allows you to very clearly convey the nature of the relief and the degree of its dissection. Therefore, this method is used today on state topographic maps.

6 Hypsometric method, or layer-by-layer coloring of elevation steps, the main and most used method of depicting relief on physical and hypsometric maps. Horizontals on overview maps called isohypsum. Isohypses serve as dividing lines between the steps of heights passing through a certain number of meters in height. On hypsometric maps of Russia, a scale is used, which is built according to the principle: the higher, the darker.

The method is very clear, it allows you to accurately measure the relief and perform work on the map. In addition, the type of relief - mountainous or flat - is well depicted and readable on the map.

The relief of the seabed is depicted in a similar way, only here layer-by-layer coloring of the depth steps is performed. Isobaths - lines of equal depths serve as dividing lines between different steps of depths. In the legend of general geographic maps, the scale of heights always includes not only the relief of the land, but also the relief of the seabed. The lowest steps of the scale, corresponding to the areas of the bottom of the seas and oceans, are colored blue. Lowlands - land areas up to 200 m - painted in green color... Land areas above 200 m are colored from light yellow (light brown) to orange (dark brown). The highest steps are usually stained with a deep brown color. There are other colors in the hypsometric scale. Well-chosen scale colors can give the impression of a three-dimensional image.

7 Relief symbols... They are used to display landforms that are not expressed by horizontals: abrupt violations of the relief, for example, rocks, gullies, cliffs, ravines, etc. In these cases, brown signs are used, which go well with horizontals. Artificial landforms, for example, quarry ledges, ditches, embankments, waste heaps, etc., are shown with black signs.

Terrain block diagrams are three-dimensional flat drawings that convey the plasticity of the earth's surface. Usually they are combined with longitudinal and cross-sections, which show the internal geological structure of the territory. Modern computer technologies make it possible to obtain three-dimensional block diagrams on the display and carry out various transformations with them.

8 Digital elevation models(DEM). DEM - a set (array, file) of elevation marks Z, taken at the nodes of a network of points with coordinates x, y and encoded in numerical form (A. M. Berlyant).

Currently, DEMs are the basis for computer mapping. With the help of DEM, various calculations are performed, the construction of maps of the density and depth of relief, inclination angles, construction of sections, lines of sight, etc. In addition, DEMs are used to model routes, profiles, to create land use areas, for example, construction sites and other design work ... DEM can currently be built in various programs, including IndorGIS, Autodesk Civil 3D, etc.

To preserve information about the relief of a particular area, mankind uses topographic maps. To convey the entire completeness of information will allow horizontal lines - closed curved lines, characterized by equal altitude above sea level. The following definitions contribute to the clarification of such subtleties:

1. Horizontal - a line of equal absolute heights earth surface... The drawing and arrangement of contour lines relative to each other allows to determine the connection and the shape of the irregularities of the territory. As the characteristics of such a concept as horizontals, they call the height of the section and the inception.

2. The height of the section is the distance separating adjacent secant surfaces. It is important to take into account the correspondence to the nature of the terrain and the scale of a particular map. For better understanding, this information is contained in text form on each sheet of the map, framed on the south side.

3. Placement is the distance from one to another adjacent contour plotted on the map. The cardinal role in understanding the map is played by the height of the section of a particular relief, as well as the degree of steepness of the slope. More precisely, the greater the angle of inclination, the less the setting.

Contours: division into views

For drawing on the map, the following types of contour lines are used:

  • main (solid), drawn by means of solid lines (corresponding to the height of the section);
  • showing important details of a semi-horizontal (half), in the form of dashed lines (after 1/2 of the section height);
  • clarifying information about the details of the relief, auxiliary contours, applied through 1/4 of the section height in the form of short dashed lines;
  • thickened horizontals, corresponding to a five-fold height of the section, facilitate the reading of maps.

The inscription at the bottom of the map, indicating solid contours drawn every 100m, means that solid thin contours are repeated every 100m, and thicker analogs are repeated every 500m.

How to choose the height of the section

When choosing the height of the section, the type of terrain and the scale of the map are taken into account. For both flat and hilly territories, the calculation of the section height provides for 0.02 of the scale value. Relative to the highlands, there is a twofold increase in the height of the section (0.04 scale). Mapping of flat-plain places is characterized by a two-fold decrease in the height of the section (0.01 scale).

The flat terrain of the Moscow region is mapped to a scale of 1: 100,000. In this case, solid areas are drawn every 20m. For high-mountainous Nepal, where the map scale is 1: 100,000, the contour lines are plotted every 40m. With the same scale of the map of a certain flat-plain area, the repetition of contour lines is observed every 10m.

Conclusion: the scale of the map of flat areas provides for drawing contour lines every 2 meters, for high-mountainous areas - every 4 meters, for flat-flat surfaces - every meter.

Slope directions: definition features

With the help of contour lines, it is possible to obtain information about the location of objects and their height. Since the application by means of contour lines, both the ridge and the hollow, is practically the same, then you have to use not only closed lines. Here, such additions to the horizontal lines as bergstrikhs are used, which make it possible to distinguish, in addition to the direction of the slopes, also the most complex relief forms.

4. Under the concept of bergstrich is meant a short line, standing (at the bend) perpendicular to the horizontal. This is how the indication of the fall of the slope is given. An understanding of the direction of the slopes will be provided by bergstriks, as well as elevation marks of different types:

  • Contour elevations, in the form of digital signatures applied along the contour lines and giving an idea of ​​the height above sea level. Moreover, the upper part of the numbers is in the area where the slope is the highest.
  • Elevation marks are digital signatures on watersheds, coastlines, hilltops, and the lowest places of valleys.

The accuracy of such labels depends on the selected scale:

  • 1: 100,000 and above - up to 0.1m;
  • 1: 200,000 and less - up to 1m.

Relief elements transmitted through conventional signs

To map specific relief details, special symbols are used. In this regard, it is worth mentioning talus, cliffs, rocks, gullies, ravines, ramparts, excavations, barrows, pits, sinkholes of the karst type, etc. Moreover, the signs of such formations are supplemented with signatures about the height or depth. What's more important: objects of natural origin are depicted in brown paint, and artificial ones - in black. The second option should include: formations of stones, grottoes, tunnels, outlier rocks, etc. In addition, passes are displayed on maps of mountainous areas, supplemented by elevation indicators and time stamp on the spot. Blue paint is used to apply firn fields, glaciers and additional signs.

Characteristic features of the relief on a small-scale map

The drawing of the relief on the maps, the scale of which is equal to 1: 500 00 and 1: 1 000 000, is carried out by means of contour lines and conventional symbols. True, here there is a generalized nature of application, when only the structure, the level of segmentation, and the main forms are shown.

The frequency of the contour lines section differs according to the type of surface:

  • for plains - 50m;
  • for mountainous areas - 100m.

And if the height above sea level exceeds 1000m, then at a scale of 1: 1,000,000, the emphasis is on the height of the section of 200m.

Application volume legend for certain objects is regulated according to the need for orientation on the ground. Moreover, the choice is made in favor of smaller versions of signs.

When plotted on a map with a small relief scale highlands, the elevation and hillshade steps are shown using paint layering. As the height of the relief increases, there is a transition from orange of different shades to brown of varying intensity. Changes in tone take place every 400, 600, 1000m (corresponding to the absolute elevation of a given territory). To plot the scales of interest, they are oriented in the same way as in the case of the cross-section of contour lines indicated on the map from the south side (under the frame).

The volumetric perception of the relief is provided by adding shadows on the slopes of mountainous reliefs. The relative steepness and height of the slope is judged by the shade of the washdown, which will provide a visual representation of valleys, canyons, mountain ranges, etc.

1.1 Types and forms of terrain

In military affairs under terrain understand the area of ​​the earth's surface on which to conduct fighting... Irregularities in the earth's surface are called topography, and all objects located on it, created by nature or human labor (rivers, settlements, roads, etc.) - local items.

The relief and local objects are the main topographic elements of the terrain, influencing the organization and conduct of a battle, the use of military equipment in battle, the conditions of observation, firing, orientation, camouflage and passability, that is, determining its tactical properties.

A topographic map is an accurate display of all the most tactically important elements of the terrain, plotted in a mutually accurate position relative to each other. It makes it possible to explore any territory in a relatively short time. A preliminary study of the terrain and making a decision for a subunit (unit, formation) to carry out a particular combat mission is usually carried out on a map, and then clarified on the ground.

The terrain, influencing the hostilities, in one case can contribute to the success of the troops, and in the other have a negative impact. Combat practice convincingly shows that one and the same terrain can give more advantages to those who study it better and use it more skillfully.

By the nature of the relief, the area is divided into flat, hilly and mountainous.

Flat terrain characterized by small (up to 25 m) relative elevations and a relatively small (up to 2 °) steepness of the slopes. The absolute heights are usually small (up to 300 m) (Fig. 1).

Rice. 1. Plain, open, slightly rugged terrain

The tactical properties of flat terrain depend mainly on the soil and vegetation cover and on the degree of ruggedness. Clay, loamy, sandy loam, peat soils allow the unhindered movement of military equipment in dry weather and significantly impede movement during rains, spring and autumn thaw. It can be cut by river channels, ravines and gullies, have many lakes and swamps, which significantly limit the maneuvering possibilities of troops and reduce the rate of advance (Fig. 2).

Plain terrain is usually more favorable for organizing and conducting an offensive and less favorable for defense.

Rice. 2. Plain wooded forest closed heavily rugged terrain

Hilly terrain characterized by the wavy nature of the earth's surface, forming irregularities (hills) with absolute heights of up to 500 m, relative elevations of 25 - 200 m and a prevailing steepness of 2-3 ° (Fig. 3, 4). Hills are usually composed of hard rocks, their tops and slopes are covered with a thick layer of loose rocks. The depressions between the hills are wide, flat or closed basins.

Rice. 3. Hilly semi-enclosed rugged terrain

Rice. 4. Hilly gully-gully semi-closed rugged terrain

The hilly terrain ensures the movement and deployment of troops hidden from enemy ground observation, facilitates the selection of sites for the firing positions of missile forces and artillery, and provides good conditions for the concentration of troops and military equipment. In general, it is favorable for both offensive and defensive purposes.

Mountain landscape represents areas of the earth's surface, significantly elevated above the surrounding terrain (having an absolute height of 500 m and more) (Fig. 5). It will be distinguished by its complex and varied relief, specific natural conditions. The main landforms are mountains and mountain ranges with steep slopes, often turning into cliffs and rocky cliffs, as well as hollows and gorges located between mountain ranges. The mountainous terrain is characterized by a sharp rugged relief, the presence of hard-to-reach areas, a sparse network of roads, a limited number of settlements, a rapid flow of rivers with sharp fluctuations in water levels, a variety of climatic conditions, and the predominance of stony soils.

Combat operations in mountainous areas are considered as actions in special conditions. Troops often have to use mountain passes, observation and firing, orientation and target designation are difficult, at the same time, it contributes to the secrecy of the location and movement of troops, facilitates the arrangement of ambushes and engineering barriers, and the organization of camouflage.


Rice. 5. Highly rugged mountainous terrain

1.2 The essence of the image of the relief on maps by contours

The relief is the most important element of the terrain, which determines its tactical properties.

The image of the relief on topographic maps gives a complete and sufficiently detailed idea of ​​the unevenness of the earth's surface, the shape and relative position, elevations and absolute heights of points of the terrain, the prevailing steepness and length of slopes.

Rice. 6.The essence of the image of the relief by horizontals

The relief on topographic maps is depicted by contour lines in combination with conventional signs of cliffs, rocks, ravines, gullies, stone rivers, etc. ... On all topographic maps, the relief is depicted in the Baltic system of heights, that is, in the system of calculating absolute heights from the average level of the Baltic Sea.

1.3 Types of contour lines

Horizontal- a closed curved line on the map, which corresponds to a contour on the ground, all points of which are located at the same height above sea level.

The following contours are distinguished:

  • the main(solid) - relief section corresponding to the height;
  • thickened - every fifth main contour; stands out for ease of reading the relief;
  • d Additional contours(semi-horizontal) - drawn by a dashed line at a relief section height equal to half of the main one;
  • auxiliary - are depicted by short intermittent thin lines, at an arbitrary height.

Distance between two adjacent the main horizontals in height are called the height of the relief section. The height of the relief section is signed on each sheet of the map under its scale. For example: "Solid contours are drawn every 10 meters."

To make it easier to count contours when determining the heights of points on the map, all solid contours corresponding to the fifth multiple of the height of the section are drawn thickly and a number is put on it indicating the height above sea level.

In order to quickly determine the nature of the surface irregularities on the maps when reading the map, special pointers for the direction of the slopes are used - bergstrichs- in the form of short lines, placed on the horizontal lines (perpendicular to them) in the direction of the slopes. They are placed on the bends of the contour lines in the most characteristic places, mainly at the tops of the saddles or at the bottom of the basins.

Additional contours(semi-horizontals) are used to display characteristic forms and relief details (bends of slopes, peaks, saddles, etc.), if they are not expressed by the main contours. In addition, they are used to depict flat areas, when the locations between the main contours are very large (more than 3 - 4 cm on the map).

Auxiliary contours are used to depict individual relief details (saucers in steppe regions, depressions, individual hillocks on flat terrain), which are not transmitted by the main or additional horizontals.

1.4 The horizontal representation of typical landforms

The relief on topographic maps is depicted by curved closed lines connecting terrain points that have the same height above the level surface, taken as the origin of the heights. These lines are called contour lines. The image of the relief with contour lines is supplemented with captions of absolute heights, characteristic points of the terrain, some contour lines, as well as the numerical characteristics of relief details - height, depth or width (Fig. 7).

Rice. 7. Representation of relief with conventional signs

Some typical landforms on maps are displayed not only by the main, but also by additional and auxiliary contours (Fig. 8).

Rice. 8. Image of typical landforms

2. Determination on the map of absolute heights and relative elevations of terrain points, ascents and descents, steepness of slopes

2.1. Determination of absolute heights and relative elevations of terrain points on the map

Rice. 9. Determination of absolute heights and relative elevations of terrain points on the map

Absolute height- the height of a point on the earth's surface above sea level; is determined by the elevations and contour lines (in Fig. 9 these are heights with elevations 33.1 and 49.8).

Relief section height is the height distance between two adjacent cutting planes.

Relative altitude(mutual excess of points)- the height of a point of the terrain above another, it is defined as the difference in the absolute heights of these points (in Fig. 9, the relative height is 16.7 (49.8-33.1)).

Rice. 10. Determination on the map of ascents and descents on the route (route profile).

Rice. 11. Determination of the steepness of the slopes on the map

Profile- a drawing depicting a section of the terrain in a vertical plane.

For greater expressiveness of the terrain, the vertical scale of the profile is taken 10 or more times larger than the horizontal.

In this regard, the profile, transmitting the mutual excess of points, distorts (increases) the steepness of the slopes.

To build a profile you need(fig. 10) :

  • draw a profile line (route of movement) on the map, attach a sheet of graded (millimeter) paper to it, transfer to its edge with short lines the places of contour lines, bend points of slopes and local objects that the profile line cuts, and sign their heights;
  • sign on a sheet of graph paper near the horizontal lines the heights corresponding to the heights of the contour lines on the map, conventionally taking the intervals between these lines for the height of the section (set the vertical scale);
  • from all the dashes denoting the intersection of the profile line with the elevation marks of the contour lines, the points of inflection of the slopes and local items, lower the perpendiculars until they intersect with the parallel lines corresponding to the elevations and mark the resulting intersection points;
  • connect the intersection points of a smooth curve, which will depict the profile of the terrain (ascents and descents on the route of movement).

The steepness of the slope on the map is determined by the location - the distance between two adjacent main or thickened contours; the smaller the laying, the steeper the slope.

To determine the steepness of the slope, it is necessary to measure the distance between the contours with a compass, find the corresponding segment on the plot of the laying and read the number of degrees (Fig. 11).

The relief is a collection of real irregularities. physical surface Earth. By their origin, relief elements are subdivided into natural and artificial. On topography

It is customary to designate relief elements of natural origin in brown color on maps, and elements of artificial origin in black. The relief is depicted using conventional signs, heights and contour lines (the main method). Symbols are used to depict relief elements that cannot be displayed using contour lines (cliffs, ravines, gullies, slopes, retaining walls, etc.). On geographical maps, the relief of the daytime surface and the bottom of the seas and oceans is depicted using washings, when creating topographic maps, this method is not used. However, when using computer technologies for creating topographic maps, the image of the relief on them using hillshade does not present any problem.

Hollow

Rice. 3.14.

If any shape of the earth's surface is cut with a horizontal plane (Fig. 3.14), then we get a certain curve, all points of which will have the same height value, therefore, two equivalent definitions of the horizontal can be given:

  • 1) horizontal - a curve obtained by a section of the earth's surface horizontal plane;
  • 2) horizontal - an imaginary curve, all points of which have the same height value.

GOST gives the following definition: "A horizontal is a line of equal heights on a map."

The height of the cross-section of the relief by contours is the distance between adjacent cutting planes (or level surfaces) when depicting the relief by horizontals. Placement - the distance on a plan or map between two adjacent contours in a given direction. Placing the slope - laying in the direction normal to the horizontals.

With the same height of the cross-section of the relief by the horizontals, the inception of the slope is less, the greater the steepness of the slope - the angle between the direction of the slope and the horizontal plane at a given point

(fig. 3.15). Consequently, by the magnitude of the slope, one can judge the steepness of the slopes. In fig. 3.15 setting the slope (1 X larger than stingray D 2 , therefore, the corresponding slope steepness is less than the slope steepness for b 2.

Rice. 3.15. Steepness and laying

To facilitate the determination of the magnitude of the angles of inclination or slopes (the slope is called the tangent of the slope), lay graphs are used, on which the slope V or the slope is indicated along the horizontal axis and, and along the vertical - the corresponding location in a given scale (Fig. 3.16).

If we compare the images of the mountain and the depression, on which they are shown using contours, the images will not differ. To distinguish them and to indicate the direction of the slopes on the plans and maps, bergstrokes are used - short strokes drawn from the image of the horizontal downward in the direction of the slope (see Fig. 3.14).

The height of the relief section depends on the complexity of the relief (the relief is considered the more difficult, the greater the steepness of the slopes) and, for example, for plans of a scale of 1: 500 it is taken equal to 0.25, 0.5, 1.0 m, and for a scale of 1: 5000 - 1.0, 2.0, 5.0 m.

The main forms of natural relief are: mountain(hill, fell), basin, ridge, valley(log, raspok, fall), slope, saddle(fig. 3.17). A curve connecting the ridge points in series with highest values heights, called watershed. The curve connecting in series the points of the valley with the lowest values ​​of heights is called thalweg.

For clarity, when depicting the relief on plans and maps, use different kinds contour lines, namely:

  • main, corresponding to the accepted height of the cross-section of the relief and drawn in the form of a solid line with a thickness of 0.12 mm in brown;
  • basic thickened, which are the main contours, the heights of which are multiples of four or five sections

relief; their thickness is taken equal to 0.3 mm. For example, when cutting a relief And = 2 m, the main thickened contours will be horizontals with heights of 10, 20, 30 m, etc .;


Rice. 3.17.

a- mountain; 6 - basin; v- slope; G- watershed, ridge; d- valley, ravine;

e- saddle

  • additional also called semi-horizontals and drawn through 0.5 cross-sections of the relief in order to depict the features of the relief that are not expressed using the main contours; they are dashed lines 0.12 mm thick;
  • auxiliary, conducted through 0.25 cross-sections of the relief, in connection with which they are also called quarter horizontals.

More precisely, then multiplicity of thickened contours with relief sections of 1, 2 or 5 m, it is five sections, and with sections of 0.25, 0.5 or 2.5 m - four sections.

So that according to maps and plans it was possible to determine the heights of points on the earth's surface, the heights of the contour lines are evenly labeled over the entire area of ​​each sheet of the plan or map. In this case, the numbers denoting the height of the horizontal are located with their head up the slope.

For the convenience of determining the heights of contour lines over the entire area of ​​the plan sheet or map, the marks of some points are signed, primarily the most characteristic ones: points of local minima or maxima, saddle points, etc.

The terrain is very rarely represented by flat areas of the earth's surface, more often it consists of many convex or concave irregularities, different in shape and size. These irregularities are called terrain relief.

The relief, along with other natural conditions, significantly affects soil-forming processes, climate, vegetation, as well as the nature and degree of economic development and engineering equipment of the area. It largely determines the nature and location of local items - hydrography, road network, settlements, etc.

Being one of the most important topographic elements that have the most significant impact on the combat use of the terrain, the relief enhances or weakens the tactical significance of local items.

From this it is clear how important, especially in military affairs, a comprehensive study and consideration of the features of the relief in solving various problems related to the equipment and use of terrain and individual local items are.

Based on this, one of the main requirements for topographic maps of all scales is that they depict with maximum detail and accuracy not only local objects, but also the terrain. Without this, even the most detailed plan will not give an integral and visual representation of the terrain and its tactical properties.

To depict the relief on maps and plans, special methods are used - special conventional signs. There are several such methods, differing in their clarity and measuring qualities. On modern topographic maps, the most accurate method is used, which makes it possible to show not only the plan position, as is done in relation to local objects, but also the spatial forms and dimensions of the terrain irregularities. Thus, a modern topographic map gives a three-dimensional representation of the earth's surface, allowing not only measurements in the horizontal plane to be made on it, but also to determine the position of various local objects in height.

The main requirement for the image of the relief is that it makes it possible to easily and accurately determine the map;

type of unevenness of the earth's surface, their relative position and connection with each other;

mutual elevation and elevation of terrain points above sea level;

direction, shape, steepness and length of slopes.

To better understand the essence of the methods of depicting relief on maps, let us briefly consider the history of this issue.



The earliest was the perspective, or picturesque, method of depicting the relief. In its most primitive form, it was used already in ancient times, for example, on Egyptian maps - 1400 years BC. This method, which prevailed in the XV - XVIII centuries, was that individual prominent peaks or mountains were depicted in perspective drawings, in the form of scattered hills, and mountain ranges - as a chain of hills or zigzag stripes. For such an image, it was not necessary to know either the height of the mountains or the steepness of the slopes. This information was not particularly required then, and most importantly, they did not know how to obtain it.

A promising method of depicting relief was also widely used on Russian maps until the second half of the 18th century, when it was significantly improved by Russian cartographers, who created one of the largest cartographic works of that time, known as the Stolistovoy map. Russian Empire(fig. 11) scale of 20 versts in inch (1: 840,000). On this map, published in 1801-1804, instead of arbitrary drawings, by which it was impossible to judge the height of the mountains, perspective conventional signs were used for the first time, showing the difference in height between the mountains (high, medium and low mountains).

The advantages of the promising method include the comparative clarity of the "picture" image of the relief, which resembles ordinary, easily readable drawings. The disadvantage of this method is the impossibility of making any measurements and calculations related to the terrain on such a map. On modern maps this method is not used, but it is widely used in artistic posters and diagrams with geographic content.

At the turn of the 18th and 19th centuries, in connection with the development of military art and the improvement of small arms, commanders and military leaders were required to study the terrain and its relief in preparation and conduct of hostilities. In these new conditions, the pictorial (perspective) method of depicting the relief could no longer satisfy them. They needed more accurate data on the landforms, their relative position, the steepness and length of the slopes, so that they could more accurately and in detail judge the terrain passability and the degree of its influence on the military operations of the troops.



Rice. 11. Part of a sheet of the Stolistovaya map of Russia (1801 - 1804)

At the beginning of the 19th century, practical needs and the further development of measuring, shooting and map publishing technology caused the need for scientific development and widespread use of new methods of depicting relief, more perfect in visibility, accuracy and their measuring qualities. This is how methods of depicting relief with strokes and hillshade appeared. Both of these methods are fundamentally similar to each other and consist in depicting the unevenness of the terrain by shading their slopes. This shading was achieved by shading the slopes or washing them with paints, and the steeper slopes were covered with a thicker shadow, which gradually weakened when moving to less steep slopes.

Compared to hillshade, the shading method is more accurate. In the 19th century, it became the main method of depicting relief on maps and plans in all countries.

In the development and application of this method, Russian topographers and cartographers play a leading role. They developed scientifically grounded scale of strokes and published on the basis of their cards outstanding for their high technical and artistic qualities. These cards include, first of all, the well-known three-verst map (1: 126,000) European Russia(Fig. 12) on 517 sheets, the production of which Russian military topographers began in 1845. This map rightly belongs to the classics of Russian and world cartography.

The depiction of the relief by strokes on Russian maps was distinguished by great expressiveness and clarity. From it it was possible to determine with sufficient accuracy the direction, shape, steepness and length of slopes, the position and actual outline of watersheds and weirs, as well as the general view, location and interconnection of uneven terrain.

Rice. 12. Part of a sheet of a three-vertex map of the European part of Russia

The disadvantage of this method of depicting the relief is its extreme complexity in execution, and, in addition, it is impossible to determine the height and excess of points from the line drawing. In addition, solid shading overloads the map, clogging up all other content, and makes it difficult to read, especially a one-color map.

Hillshading is easier to perform than shading. The hillshaded image of the relief is quite visual, but it is unsuitable for any measurements and calculations: from such a map it is impossible to determine precisely neither the direction nor the steepness of the slopes. Currently, hillshade is used on our topographic maps of scales 1: 500,000 and 1: 1,000,000 in combination with contours as an aid to improve the clarity of the relief image. As the main method, hillshade is used on many small-scale geographic maps.

In the second half of the 19th century, in connection with new requirements for maps that arose as a result of the further equipping of armies with small arms and artillery weapons, shading was replaced by a more perfect way of depicting relief - horizontals.

The use of the method of contours, based on accurate measurements of heights and elevations of points on the earth's surface, finally determined the role and significance of the topographic map as an accurate measuring document about the terrain. Due to its high measuring qualities, not inherent in others known methods, it has survived to this day as the main one for depicting relief on modern topographic maps.

Landforms

Landforms can be positive or convex (mountains, mountain ranges, hills, etc.) and negative or concave (depressions, hollows, river valleys, etc.).

Each form of relief is formed by surfaces - slopes (slopes) of various lengths, steepness, heights and orientations. Crossing each other at different angles and in different directions, the slopes form various elementary relief forms, which can be reduced to the following five typical forms:

1. Mountain - an area of ​​the earth's surface, significantly raised above the surrounding area (500 m or more above sea level). The highest part of the mountain is called the mountain peak. It can be peak-like, plateau-like and other shapes. The upper point of a mountain peak is called a top, the lower part of the mountain (base) is called the foot, and the slope from peak to foot is called a slope.

The hill is usually rounded or oval in shape with gentle slopes and sometimes a weakly pronounced foot, with a relative height of up to 200 m is called a hill or height. The artificially created hills are called mounds.

The elevation (mountain, height) that dominates the surrounding terrain is called the command height.

2. Mountain range is a large, linearly elongated positive relief form with distinct slopes intersecting in the upper part.

The line dividing the flow of atmospheric water along two slopes directed in different directions is called a watershed.

The sharply expressed summit of the ridge is called the ridge. It usually has a sharp toothed shape, dissected into separate peaks by saddle saddles. In the longitudinal section, the crest of the ridge is a wavy line, its protruding parts correspond to the peaks. The mountain range in the plan outline has a winding shape with mountain spurs extending to the sides and their smaller branches.

An elongated hill with gentle slopes, gradually turning into a plain, and a not sharply pronounced sole is called a hump. A small elongated hill with a well-defined sole is called a ridge.

3. Basin - a depression, as a rule, of a bowl-like shape. It can be closed on all sides or open in one or two directions. The lower part of it is called the bottom. Sometimes the bottom of the basin is swampy or occupied by a lake. A small depression with a shallow depth and a flat bottom is called a saucer or depression. A very small basin is called a pit.

4. Hollow - an elongated depression, descending in one direction and having gentle, usually soddy slopes. The slope of a hollow with a pronounced upper bend is called an edge, and the line along the bottom to which the slopes are directed and which connects the lowest points, the deepest parts of the bottom, is called thalweg. The hollows are often overgrown with bushes or forests. Their bottom is sometimes swampy.

Hollows, large in size, usually with gentle slopes and a slight slope of the bottom, are called valleys. Rivers flow along the bottom of most of the valleys.

Deep steep erosion formed by temporary streams are called ravines. They arise on elevated plains, slopes of hills or hollows, composed of loose, easily eroded rocks. Their length can reach 5-10 km, width - up to 50 m, and depth -
30 m and more. The steepness of the slopes of the ravines depends on the composition of the soil and often reaches 45-50 ° and more. Under the constant influence of melt and rainwater, they rapidly increase. Over time, after reaching the waterproof layer, the ravine stops growing in depth, its slopes become more gentle, overgrown with grass and it turns into a ravine. A gully is a dry valley or a valley with a temporary watercourse. Its bottom is gently concave, the slopes are convex. The length of the ravine is from hundreds of meters to 20-30 km, the width at the top is usually 100-250 m, at the bottom 15-30 m, the depth varies from 20 to 50 m. The steepness of the slopes of the beams reaches 10-25 °. The slopes and the bottom are usually turf and often covered with woody vegetation.

A large ravine with a wide flat bottom and gentle slopes - a type of dry valley, filled occasionally in spring or during floods with waters, is called dry land.

Small erosions (the first stage of development of ravines) with steep exposed walls and a narrow, sometimes winding bottom are called gullies.

Horizontal or slightly sloping sites of various origins on the slopes of mountains, river valleys and on the shores of lakes and seas, limited by ledges, are called terraces. They are single or arranged in the form of steps one above the other. The most widespread are river terraces, which are developed on the slopes of most river valleys and are remnants of the former bottom.

Deep river valleys with very steep, often steep slopes and a narrow bottom, usually completely occupied by the river bed, are called canyons. Their depth can reach several tens, and sometimes hundreds of meters.

Narrow and deep mountain gullies with steep, in places sheer rocky slopes and a narrow winding bottom are called gorges. In contrast to the canyon, the bottom of the gorge is somewhat wider and is not completely occupied by the river bed.

Deep and narrow hollows in the mountains, with steep or overhanging slopes, made entirely of bedrock, are called gorges. Their width is insignificant, and the bottom is completely occupied by the river bed, which usually has a high flow rate.

5. Saddle - a depression between the peaks of a mountain range. It is almost always the starting point for two ravines diverging in opposite directions.

The lowest and most accessible place in the ridge of a ridge or massif is called a pass. As a rule, the pass is located in the saddles, less often on the sloping parts of the ridges. The height of the passes depends on the height of the mountain ranges.

Deeply cut and low-lying saddles on both slopes of one ridge or between two mountain ranges are called mountain passes.

The image of the main landforms by horizontal lines is shown in Fig. 13.

Rice. 13. Image on the map by contours of typical relief forms

The image of the relief with contour lines is supplemented with captions of absolute heights, characteristic points of the terrain, some contour lines, as well as the numerical characteristics of relief details - height or depth, width (Appendix 4).

The image of the relief on topographic maps gives a complete and sufficiently detailed idea of ​​the unevenness of the earth's surface, their shape and relative position, the elevations and absolute heights of terrain points, the prevailing steepness and length of the slopes.

The essence of the relief image by horizontals. A horizontal line is a closed line that depicts a horizontal contour of irregularities on the map, all points of which on the ground are located at the same height above sea level. Horizontals can be thought of as lines obtained by slicing terrain with level surfaces, that is, surfaces parallel to the water level in the oceans.

The essence of the image of the relief by horizontals on topographic maps will be considered in the following example. Suppose that the mountain model (Fig. 14) is cut by three parallel horizontal planes 1, 2 and 3 in such a way that the plane coincides with the level surface. All planes are located at the same distance from each other, called the section height. In this case, the section height is 10.

Each plane will have a certain height above the level surface: H 1 = 0, H 2 = 10, H 3 = 20. Crossing the surface of the mode

Rice. 14. The essence of the relief image by horizontals:

1, 2, 3 – relief section plane

whether it forms a curved line with a plane that connects points of the model that are at the same height: a curve located in a plane 1 , connects points whose height is zero; curve obtained by cutting a surface by a plane 2 , connects points of the model with a height of 10; all points of the model surface located on a curve that is a trace of the surface section by a plane 3 , will have a height of 20. The projection of the obtained curves on the plane will give an image of the mountain with contours. Thus, the horizontal lines can be considered as traces of the cross-section of the terrain by imaginary horizontal planes.

In order to distinguish a convex relief (mountain, ridge) from a concave (hollow, hollow), as well as to quickly determine the direction of the slope, strokes are placed on the horizontals - slope indicators, which with their free ends are directed towards the lowering of the slope.

The steepness of the slope- the angle made up by the direction of the slope with the horizontal plane and is characterized on the map by the distance between two adjacent horizontals, called the location.

Relief section height - it is the difference between the heights of two adjacent secant surfaces. On the map, it is expressed by the difference in heights of two adjacent contours. Within the limits of the map sheet, the height of the relief section is, as a rule, constant.

With the same height of the relief section, depending on the change in the steepness of the slope, the value of the location also changes. Lay 3 1 (Fig. 15), which corresponds to the slope steepness KC 1 = 10 °, is twice as large as 3 2, which corresponds to the steepness of the slope KC 2 = 20 °. It follows from this that the steeper the slope, the less the incidence, and vice versa, the more the slope is, the greater the incidence. Therefore, when depicting steep slopes, horizontal lines on the map are located more often, and shallow ones - less often.

Rice. 15. Relationship between the slope steepness and the value of the laying

with the same section height

The property of contour lines to transmit the steepness of the slope allows you to display its shape on the map. In its shape, the slope can be flat, convex, concave and wavy.

For an even slope, the horizontal lines are located at equal distances from one another, for concave, convex and wavy slopes, the distances between the horizontals increase or decrease depending on the change in the steepness of individual sections between the slope bends.

For each scale of maps and type of terrain, the height of the relief section is regulated. Table 1 shows the section heights adopted on topographic maps of the Republic of Belarus.

The height of the main section is labeled on each sheet of the map under a linear scale, for example: “Solid contours are drawn through
5 meters".

Types of contour lines. Symbols of relief details. The contours, which correspond to the main relief section, are called the main ones (Fig. 16). They are drawn on the map with thin solid lines; for the convenience of counting, every fifth horizontal line is thickened. To display individual vertices, hollows and saddles that cannot be expressed on the map by the main contours, additional (through half the height of the main section) and auxiliary (through about a quarter of the main section) contours are applied. They are drawn on the maps with dashed lines, and the length of the links of the auxiliary contour lines is approximately two times less than that of the additional ones.

Table 1

Relief section height

For additional characteristics of the relief, the elevation marks of the characteristic points of the terrain are signed on the maps: the tops of mountains and hills, the highest points of watersheds, passes, saddles, the lowest points of the bottom of valleys, as well as points that are landmarks (at the intersections of roads and glades, on sharp cover, etc.). The elevation marks of the most prominent points of the terrain (command - having the greatest height and allowing good overview from the surrounding area) are highlighted in larger print. Such marks are selected in the amount of 3-4 per map sheet.

Contour lines labels are given in such a quantity and are placed in combination with the elevation marks of the points so that you can easily and quickly determine the height of a particular point on any part of the map sheet.

Rice. 16. Types of contour lines

Study of the relief on the map

The terrain is studied, as a rule, simultaneously with the general study of the area in the following sequence:

1. Study of the general nature of the relief of a given area of ​​the terrain (flat, hilly, mountainous relief, the degree of its dissection by ravines, ravines, hollows, etc.) by reviewing the outline and density of contour lines on the map.

The contours on the map of flat terrain have a relatively straight, somewhat winding outline. The size of the deposits is 1 cm or more. On the maps of flat terrain, there are many additional and secondary contour lines that display all the relief details that do not fall into the main sections.

The contours of the hilly terrain are located closer to each other and have a rounded shape, forming closed figures of small size.

The horizontals of the mountainous terrain on the map are close to one another, the layouts between them on the slopes of the mountains do not exceed 1-2 mm. On the maps of such terrain, there are many conventional signs of relief elements that are not expressed by horizontals.

2. Determination of the relationship between the nature of the relief and the location of hydrographic objects (rivers, streams, lakes, swamps, etc.) in order to establish the pattern of the location of unevenness of the earth's surface, the direction of watersheds, the nature and length of natural boundaries. The establishment of such relationships is checked and specified by the elevation marks of points, contour lines, water edges in rivers and lakes, as well as by direction indicators of slopes. As a result, they get a general picture of the relative position of the main watersheds and valleys, and also determine the most important of them, which can have a significant impact on the fulfillment of a combat mission.

3. A detailed study and assessment of the size and tactical properties of individual forms and details of the relief in mutual connection with the elements of the combat formations of troops located on them. The study of the relief in this case consists, first of all, in determining the heights of points, the elevations between them, the direction and steepness of the slopes.

To quickly distinguish horizontally the landforms and the direction of the slopes, you must remember the following:

1. At elevations (mountains, ridge), their convexities are always directed towards the lowering of the slope, and at concave landforms (hollows, hollows), on the contrary, towards the increase.

2. The horizontals, denoting the saddle, face it from all sides with bulges, forming, as it were, a platform; these horizontals on both sides of the saddle indicate the tops, and on the other two sides - the beginning of two valleys, diverging from the saddle in opposite directions.

3. The terrain always descends towards the rivers and other bodies of water located on it. Consequently, in order to determine the general direction of lowering the terrain and slopes of individual elevations, it is necessary, first of all, to consider on the map how large reservoirs are located, where rivers flow, and from these data to judge the general direction of slopes. This task is facilitated by the fact that on the maps the hydrographic network stands out sharply in its blue, or light blue color.

4. There are known regularities in the mutual arrangement of the unevenness of the terrain: ridges usually move away from a mountain, a hill, or are spurs of other, larger ridges; the slopes of the hills most often represent an alternation of ridges and valleys, which on the map corresponds to the same alternation of undulating bends of the horizontal lines, the bulges of which are alternately turned in one, then in the other, opposite direction.

The shapes of the slopes are determined by the relative position of the contour lines on the slope. If the slope is even, its contours on the map are located at equal distances from one another; with a concave slope, they become more frequent towards the top, and with a convex slope, on the contrary, towards the sole. With a wavy slope, the horizontal lines on the map become more frequent and thinner in several places, depending on the number of bends of the slope.

It is advisable to start the study of the relief on the map by considering how the reservoirs are located in this area; this will make it possible to immediately determine the general direction of the slopes of all uneven terrain in relation to them. Then you should consider all the other signs indicating the direction of the slopes (slope indicators, elevations of contour lines and heights of individual points) and check on them the correctness of determining these directions. This will make it possible to finally establish which contours represent the peaks and which - the hollows.

Further, it is required to sequentially consider all the undulating bends of the contour lines on the slopes of these irregularities. Considering that each horizontal bend necessarily means a ridge or hollow, it is necessary to establish how their bulges are located (oriented) in relation to the general direction of the slope lowering, and thereby determine the alternation of ridges and hollows extending from each peak or descending into the hollow. Having clarified all this, it is necessary to establish the location and nature of all saddles.

Study of landforms that are not expressed by horizontals... Individual forms and details of the relief, which are not expressed by horizontal lines, but which are important for the troops, are depicted by their conventional symbols. Natural landforms are shown on the map with conventional signs in brown, and artificial ones - in black.

Ravines and gullies up to 5 m wide are depicted on maps with scales of 1:25 000 and 1:50 00 in one line. Ravines more than 1 mm wide on the map scale are shown in two serrated lines. The bottom of ravines with a width of 3 mm or more on a map scale is depicted as horizontals. Near images of ravines and gullies 1 mm wide and less, their width (at the top) and depth in meters are marked. When the width of the ravines is more than 1 mm, only their depth (the height of the cliff) is signed.

On cards special conventional sign show sodded ledges (edges). The breaks are shown at a length of at least 3 mm on the map scale. When designating cliffs, their relative heights are signed in meters.

The debris on the maps is depicted with their division into sandy, clayey, stony-gravel and pebble.

The maps show individual rocks, outcrops, huskies (narrow circular ridges of hard rocks), mounds and hillocks, ramparts and pits. Their designations are accompanied by labels of relative heights or depths in meters.

Determination of ascents and descents... While moving through unfamiliar terrain, it is often necessary, guided by the relief of the map, to check your location, observing the alternation of ups and downs along the way. In this case, it is required to determine the boundaries of ascents and descents along the horizontals of the map and identify the points corresponding to them on the terrain with them. These boundaries, as a rule, coincide with the characteristic points and lines of the relief (peaks, saddles, watersheds, weirs), to the finding of which, in essence, this task is reduced.

For example, let us trace the nature of the relief along the road from a separate tree (Fig. 17 a) to the bridge. From tree 1, the ascent begins, which continues to the watershed of ridge 2. Next, there is a descent into the hollow to the weir 3, then again ascend to the watershed 4. From here, the descent to the saddle 5 begins, then the ascent to the top 6 and again the descent to turn 7. Between points Routes 7 and 8 run parallel to the horizontal, so there will be no ups and downs on this section. Further from point 8 the descent to the bridge continues.

In fig. 17 b shows an undulating slope of unevenness along which the road passes. To determine the ups and downs on this road, it is necessary to establish what forms of relief it passes through. The slope pointer in this case shows us the general direction of the slope. The same direction of the slope shows the position of the stream. There is an increase from the stream to the right; when moving along the road from the bridge to the tree, there will be ups in sections 1–2, 3–4, 5-6, 7–8, and descents in the rest of the sections.

In fig. 17c shows the case when the road passes on the map between two adjacent contours without crossing them. In this case, when driving from right to left on sections 1–2, 3-4, 5-6 and 7-8 there will be descents, and on other sections there will be ascents. And only when moving along the horizontal direction, for example, on section 8-9, there will be no ups and downs.

Rice. 17. Determination of the boundaries of ascents and descents.

10. Out-of-the-box design of cards

Various information necessary for working with the map is placed outside the map sheet.

The arrangement of the elements of the out-of-frame design of maps of scales 1:25 000–1: 100 000 is shown in Fig. eighteen.

Rice. 18. Arrangement of elements of out-of-frame design of maps of scales 1:25 000 -

1 - coordinate system; 2 - the name of the republic and region, the territory of which is shown on this sheet of the map; 3 - the name of the department that prepared and issued the map; 4 - the name of the most significant settlement; 5 - neck of the card; 6 - nomenclature of the card sheet (digital and alphanumeric); 7 - year of issue of the map; 8 - the year of shooting or compilation and the source materials for which the map was compiled; 9 - performers; 10 - scale of laying; 11 - numerical scale; 12 - the magnitude of the scale; 13 - linear scale; 14 - section height; 15 - system of heights; 16 - diagram of the relative position of the vertical line of the coordinate grid, true and magnetic meridians and direction corrections; 17 - data on magnetic declination, convergence of meridians and annual change in magnetic declination

In the title of the sheet of the map, they give the name of the most significant settlement among those shown on the sheet, and if there are no settlements on this map, then place the name of an important or large object (mountains, pass, lakes, etc.).

On the left above the frame, the coordinate system and the political and administrative affiliation of the territory shown on the map are indicated. To the right above the frame indicate the type of the card, the nomenclature and the year of publication.

Under the lower (southern) side of the frame on the left, data on the magnetic declination, the convergence of the meridians and the direction correction are given. In the explanatory text about the declination of the magnetic needle and the convergence of the meridians, they indicate which year the declination is given and the magnitude of its annual change is given. The values ​​of the declination of the magnetic needle, the annual change in the declination and the convergence of the meridians are indicated in degrees and divisions of the goniometer.

In the explanatory text and in the drawing placed to the right of the text, an amendment to the directional angle is also given for the transition from it to the magnetic azimuth in divisions of the goniometer. If a magnetic anomaly is noted in a given area, then the declination value of the magnetic needle in the drawing is not signed on the corresponding sheets of the map, and the values ​​of the declination of the magnetic needle and the convergence of the meridians are given in the text.

Under the southern frame of the map, a linear and numerical scale maps, indicate the magnitude of the scale and the height of the relief section, to the right of the scale give the scale of the inceptions, designed to determine the steepness of the slopes.

Under the box on the right, there is a text that sets out information about the method of creating the map, the time of shooting, as well as about the materials used in compiling and updating the map sheet.

Outside the frame of the sheet (on the east side), various additional information(about the geodetic base, terrain passability, etc.), as well as additional conventional signs.

Between the inner and outer lines of the frame of the map sheet, the digitization of the vertical and horizontal lines of the coordinate (kilometer) grid and the labels of the geographic coordinates of the corners of the frame are given. The sides of the frame are divided into minute divisions (in latitude and longitude), and each minute division by dots is divided into six parts, ten seconds each.

At the exits outside the frame of the map of railways and highways, the name of the nearest city or village to which this road leads, indicating the distance in kilometers from the frame to this settlement, is placed.


CHAPTER 3. MAP MEASUREMENTS