{"id":804,"date":"2019-07-20T11:51:08","date_gmt":"2019-07-20T18:51:08","guid":{"rendered":"https:\/\/blogs.ubc.ca\/topo\/?page_id=804"},"modified":"2020-05-21T17:23:21","modified_gmt":"2020-05-22T00:23:21","slug":"contours","status":"publish","type":"page","link":"https:\/\/blogs.ubc.ca\/topo\/tools-knowledge\/fundamentals\/contours\/","title":{"rendered":"Contours"},"content":{"rendered":"<h1>Contours<\/h1>\n<div id=\"random-accordion-id-266\" class=\"accordion-shortcode  accordion-container\">\n<h3 ><a href=\"#characteristics-of-contour-lin-0\" >Characteristics of Contour Lines <\/a><\/h3><div id=\"characteristics-of-contour-lin-0\" class=\"accordian-shortcode-content \" ><\/p>\n<p>Contour lines are a graphic device used for hundreds of years to describe three-dimensional land form through a two-dimensional drawing or image. As a graphic, they have a long and rich history (check out the <a href=\"https:\/\/thegreatlinesproject.wordpress.com\/\">Great Lines website<\/a> from Karen Rann for a look into their history) and they are still in wide use in the design and construction industries today. Even for designers working through digital models in which three-dimensional land form is represented as surfaces and meshes, contour lines provide an efficient way to visualize more information (ie, slope, drainage, relative heights, etc.) from a three-dimensional model without relying on simulated light or rendering. They also remain critical for translating designs into contour plans that contractors can use to construct earthwork.<\/p>\n<p>Contours are horizontal section profiles:<\/p>\n<div style=\"padding: 76.92% 0 0 0; position: relative;\"><iframe style=\"position: absolute; top: 0; left: 0; width: 100%; height: 100%;\" src=\"https:\/\/player.vimeo.com\/video\/353261241?loop=1&amp;title=0&amp;byline=0&amp;portrait=0\" frameborder=\"0\" allowfullscreen=\"allowfullscreen\"><\/iframe><\/div>\n<div style=\"text-align: center;\"><em>contour lines slice topography horizontally, representing a string of points at the same elevation<\/em><\/div>\n<p>&nbsp;<\/p>\n<p>Every contour line forms a closed polygon, even if its full extents are not shown within the boundary of your drawing or survey:<\/p>\n<div style=\"padding: 76.92% 0 0 0; position: relative;\"><iframe style=\"position: absolute; top: 0; left: 0; width: 100%; height: 100%;\" src=\"https:\/\/player.vimeo.com\/video\/353261288?loop=1&amp;title=0&amp;byline=0&amp;portrait=0\" frameborder=\"0\" allowfullscreen=\"allowfullscreen\"><\/iframe><\/div>\n<div style=\"text-align: center;\"><em>contour lines always form closed lines, even if it is not shown within the extents of your drawing (adapted from Strom, 2013)<\/em><\/div>\n<p>&nbsp;<\/p>\n<p>The steepest slope from <span style=\"font-size: 1rem;\">any point on a contour line is the perpendicular line (the shortest line) to the next contour line down (ie, where the greatest vertical change is achieved in the shortest horizontal distance). <\/span><span style=\"font-size: 1rem;\">Consistent with the preceding point, water flows along the shortest line (the perpendicular line) between contours until it reaches a low point (LP) \/ depression \/ water body:<\/span><\/p>\n<div style=\"padding: 76.92% 0 0 0; position: relative;\"><iframe style=\"position: absolute; top: 0; left: 0; width: 100%; height: 100%;\" src=\"https:\/\/player.vimeo.com\/video\/353261264?loop=1&amp;title=0&amp;byline=0&amp;portrait=0\" frameborder=\"0\" allowfullscreen=\"allowfullscreen\"><\/iframe><\/div>\n<div style=\"text-align: center;\"><em>the blue lines run perpendicular from one contour to the next, representing the shortest line between contours, where the slope is most severe, and the path of stormwater run-off (adapted from Strom, 2013)<\/em><\/div>\n<p>&nbsp;<\/p>\n<p>Contour lines also follow these general rules:<\/p>\n<ul>\n<li style=\"list-style-type: none;\">\n<ul>\n<li>\"The steepness of slope increases as the distance between contour lines decreases.\" (Strom, 2013)<\/li>\n<li>\"Equally spaced contour lines indicate a constant \/ uniform slope.\" (Strom, 2013)<\/li>\n<li>\"Contour lines never cross except where there is an overhanging cliff, natural bridge, or other similar phenomenon.\" (Strom, 2013)<\/li>\n<li>\"Contour lines never divide or split.\" (Strom, 2013)<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<p>Strom, Steven, Kurt Nathan, and Jake Woland. 2013.\u00a0<i>Site engineering for landscape architects<\/i>. Hoboken: John Wiley &amp; Sons.<\/p>\n<p>\n<\/div>\n<h3 ><a href=\"#graphic-standards-for-contour--1\" >Graphic Standards for Contour Lines<\/a><\/h3><div id=\"graphic-standards-for-contour--1\" class=\"accordian-shortcode-content \" ><\/p>\n<p>Below is a snapshot of a proposed grading plan. Plans can get busy and messy and the key is to achieve balance between information and graphic clarity. Appropriate usage of line-weights, line-types, hatching and symbols is crucial in making readable contour plans.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-951\" src=\"https:\/\/blogs.ubc.ca\/topo\/files\/2019\/08\/Graphic-STD.jpg\" alt=\"\" width=\"3560\" height=\"1684\" \/><\/p>\n<p>Some key graphic principles:<\/p>\n<ul>\n<li style=\"list-style-type: none;\">\n<ul>\n<li style=\"list-style-type: none;\">\n<ul>\n<li>Every fifth contour is bold.<\/li>\n<li>Contours should generally be expressed as whole numbers (except when using 0.5m or 0.25m contours, in which cases the smallest decimal possible should be used).<\/li>\n<li>Contour labels always go on the uphill side of the contour.<\/li>\n<li>Spot elevations should be labeled with a consistent graphic where contour lines are insufficient to express the landform; identified to the hundredth of a decimal.<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<p>The legend is an integral part of any grading &amp; drainage plan. It explains the content in the plan and insures the plan's intent is clear. The legend below demonstrates typical symbols and abbreviations used in a grading &amp; drainage plan.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter wp-image-881 \" src=\"https:\/\/blogs.ubc.ca\/topo\/files\/2019\/07\/screen-shot.jpg\" alt=\"\" width=\"282\" height=\"557\" \/><\/p>\n<p>\n<\/div>\n<h3 ><a href=\"#linksother-resources-2\" >Links\/Other Resources<\/a><\/h3><div id=\"linksother-resources-2\" class=\"accordian-shortcode-content \" ><\/p>\n<p><a href=\"https:\/\/blogs.ubc.ca\/topo\/tools\/#Script_03\" target=\"_blank\" rel=\"noopener noreferrer\">Link to useful GH scripts &amp; Rhino files<\/a><\/p>\n<p><a href=\"https:\/\/thegreatlinesproject.wordpress.com\/\" target=\"_blank\" rel=\"noopener noreferrer\">The Great Lines project to investigate the invention of the contour line, from Karen Rann<\/a><\/p>\n<p><a href=\"https:\/\/canvas.uw.edu\/courses\/1012396\/files\/32867584\/download?wrap=1\" target=\"_blank\" rel=\"noopener noreferrer\">Understanding Contours, from Richard K Untermann, University of Washington<\/a><\/p>\n<p>\n<\/div>\n<\/div><!-- #random-accordion-id-266end of accordion shortcode -->\n","protected":false},"excerpt":{"rendered":"<p>Contours<\/p>\n","protected":false},"author":59288,"featured_media":0,"parent":742,"menu_order":1,"comment_status":"open","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-804","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/blogs.ubc.ca\/topo\/wp-json\/wp\/v2\/pages\/804","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/blogs.ubc.ca\/topo\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/blogs.ubc.ca\/topo\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/blogs.ubc.ca\/topo\/wp-json\/wp\/v2\/users\/59288"}],"replies":[{"embeddable":true,"href":"https:\/\/blogs.ubc.ca\/topo\/wp-json\/wp\/v2\/comments?post=804"}],"version-history":[{"count":48,"href":"https:\/\/blogs.ubc.ca\/topo\/wp-json\/wp\/v2\/pages\/804\/revisions"}],"predecessor-version":[{"id":1328,"href":"https:\/\/blogs.ubc.ca\/topo\/wp-json\/wp\/v2\/pages\/804\/revisions\/1328"}],"up":[{"embeddable":true,"href":"https:\/\/blogs.ubc.ca\/topo\/wp-json\/wp\/v2\/pages\/742"}],"wp:attachment":[{"href":"https:\/\/blogs.ubc.ca\/topo\/wp-json\/wp\/v2\/media?parent=804"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}