![]() Have students label the base of the mountain on the contour map with 0 feet and then assign consistent elevations to the other levels using an elevation range of 100 feet per line. Tell pairs to assume that the base of the mountain is at sea level, or 0 feet of elevation. Have pairs complete the contour maps with DOGSTAILS. Make sure students realize they have drawn contour lines for a topographic map.Ħ. Have students outline this layer and repeat the process with the top two layers. Then have students remove the bottom layer of clay and place the next largest layer of clay within the first outline. Ask pairs to put the bottom layer of clay on the second piece of drawing paper and outline it. Have pairs re-draw orientation lines on the second sheet of drawing paper. Have pairs use the clay layers to draw contour lines. When they finish, each student should have four separate layers.ĥ. Then have students hold the fishing line very taut and use it to slice all the way through the clay along the rings. The first ring should be a quarter of the way down from the peak the next should be halfway down and the third should be three-quarters of the way down. Next, have pairs use their pencils to mark three rings on their clay mountains to indicate different elevations. ![]() Have pairs cut layers out of the mountains. Ask students to line up the dot with the intersection of the two lines, and draw the lines across the mountain so the clay mountain is clearly divided into the four quadrants.Ĥ. Have pairs shape their clay into a mountain on the drawing paper and mark its peak with a dot. Have pairs of students work together to make clay mountains. Explain that the peak of the mountain will line up with the intersection, so that each mountain appears to be divided into four quadrants.ģ. Tell students to draw a straight vertical line and then a straight horizontal line intersecting it to create four equal quadrants. Have pairs draw orientation lines on the drawing paper. Provide each pair with the following supplies: two sheets of drawing paper, a ball of clay, markers of different colors, several feet of fishing line, and a pencil.Ģ. Then tell students that they are going to make their own contour maps with DOGSTAILS. Ask students to describe how the map uses contour lines to show which terrain is steep and which is flat. Point out the flattest and steepest areas on the Crater Lake map. Make sure students understand that contour maps, though 2-dimensional, use contour lines to show elevation above sea level. Show students map images and introduce the activity.ĭisplay the images of topographic, or contour, maps. From the contours, it is possible to determine the capacity of a reservoir.1. This study is very important in locating bunds, dams and also to find out flood levels.Ħ. Catchment area and hence quantity of water flow at any point of nalla or river can be found. The routes of the railway, road, canal or sewer lines can be decided so as to minimize and balance earthworks.ĥ. Intervisibility of any two points can be found by drawing profile of the ground along that line.Ĥ. It helps in finding out depth of cutting and filling, if formation level of road/railway is decided.ģ. ![]() By drawing the section in the plan, it is possible to find out profile of the ground along that line. Suitable site for the project works to be taken up.Ģ. A civil engineer studies the contours and finds out the nature of the ground to identify. 17.5).Ĭontour maps are extremely useful for various engineering works:ġ. If contour lines cross each other, it shows existence of overhanging cliffs or a cave (Fig. If contour lines are meeting in some portion, it shows existence of a vertical cliff (Fig. Contour lines generally do not meet or intersect each other.ġ1. Contour lines with V-shaped with convexity towards higher ground indicate valley (Fig. Contour lines with U-shape with convexity towards lower ground indicate ridge (Fig. Approximately concentric closed contours with increasing values towards centre indicate hills.Ĩ. Approximately concentric closed contours with decreasing values towards centre (Fig. Irregular contours indicate uneven surface.Ħ. Equally spaced contour indicates uniform slope.ĥ. Closely spaced contour indicates steep ground.Ĥ. Widely spaced contour indicates flat surface.ģ. Contour lines must close, not necessarily in the limits of the plan.Ģ. The contours have the following characteristics:ġ. On contour lines the level of lines is also written. 17.1 shows contours in an area with contour interval of 1 m. The contour lines in an area are drawn keeping difference in elevation of between two consecutive lines constant. Such lines are drawn on the plan of an area after establishing reduced levels of several points in the area. A contour line is a imaginary line which connects points of equal elevation.
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