Gentle slope

• Fieldwork Techniques • Data Presentation • • • • • • • • • • • • • • • • • • • • • • • Kite Data Entity Example • Kites Data Entity Maker • • • • • • Pie Chart Maker Example • • • • • Polar Overlays Example • • • • Proportional Circle Maker • • • • • • • • • • • • • • Triangular Graph Example • • Fieldwork Methods • • • • • • • Mapping Techniques • • • • • • • • Sampling Methods • • • • • • • • • Statistical Methods • • • • • • • • n • • • • • Simpson's Diversity Index • • • • • • • • Measuring Slope Steepness The easiest way to determine the percent slope of an area is to measure the change in height (elevation over a measured distance), then calculate the percentage of slope. Use the following formula to determine slope: Rise ÷ Run = Slope % OR (Change in elevation ÷ measured distance = slope %) e.g. 30 metres ÷ 100 metres = .3 or 30% Calculating a slope steepness index for a map area Stages: • Calculate map area in km² • Place 10 X 10 grid overlay over map • Calculate % slope for each grid square • Present results as an area average or median slope for the area (see chart example below) Slope (%) Approximate degrees Terminology 0 - 0.5 0 Level 0.5 - 2 0.3 - 1.1 Nearly level 2 - 5 1.1 - 3 Very gentle slope 5 - 9 3 - 5 Gentle slope 9 - 15 5 - 8.5 Moderate slope 15 - 30 8.5 - 16.5 Strong slope 30 - 45 16.5 - 24 Very strong slope 45 - 70 24 - 35 Extreme slope 70 - 100 35 - 45 Steep slope > 100 > 45 Very steep slope Standard slope descriptors

Chapter 5 Weathering and Soil 5.4 Weathering and the Formation of Soil Weathering is a key part of the process of soil formation, and soil is critical to our existence on Earth. In other words, we owe our existence to weathering, and we need to take care of our soil! Many people refer to any loose material on Earth’s surface as soil, but to geologists (and geology students) soil is the material that includes organic matter, lies within the top few tens of centimetres of the surface, and is important in sustaining plant growth. Soil is a complex mixture of minerals (approximately 45%), organic matter (approximately 5%), and empty space (approximately 50%, filled to varying degrees with air and water). The mineral content of soils is variable, but is dominated by clay minerals and quartz, along with minor amounts of feldspar and small fragments of rock. The types of weathering that take place within a region have a major influence on soil composition and texture. For example, in a warm climate, where chemical weathering dominates, soils tend to be richer in clay. Soil scientists describe soil texture in terms of the relative proportions of sand, silt, and clay, as shown in Figure 5.14. The sand and silt components in this diagram are dominated by quartz, with lesser amounts of feldspar and rock fragments, while the clay component is dominated by the clay minerals. Figure 5.14 The U.S. Department of Agriculture soil texture diagram. This diagram applies only to the mineral co...

How do you calculate slope percentage? You can calculate the slope percentage by dividing the total elevation gain (rise) by the total horizontal distance (run). You then multiply that number by 100 to give you a percentage. For example, you have a driveway that is 50 feet long and is 4 feet higher at the end than at the beginning. Example: Rise / Run X 100 = Slope% 4′ / 50′ X 100 = 8% slope How is slope represented? As an angle Example: 10° Angles are measured in degrees and are more commonly used in construction horizontal (in plan) rather than vertically. Where is slope percentage used? The slope of a site The slope of a site can have a significant impact on its use. Gentle slopes are easier to build on and more useful for recreation. Steeper slopes are more expensive to build on and will require more grading or retaining structures to keep the slopes stable. Structures like retaining walls, rip rap, or terracing are examples of retaining structures. 10% slope Challenging to build on or use for outdoor activities. > 25% slope Subject to erosion and much more difficult to build on. >1% is preferred in grassy areas to minimize any standing water Designing walkways Walkways should be designed so that they are sloped enough to keep water from puddling, but not so steep to be difficult for some populations to use. 0.5% minimum grading for drainage is suggested, but 1.5% is preferred. Part of designing a site for everyone is designing an accessible route from handicap parkin...

\( \newcommand\) • • Here in the Pacific Northwest, we are fortunate to work in a landscape of varied landforms – from volcanic peaks to wide valleys; from steep, forested hillsides to gently rolling savannas; from rapidly cascading mountain streams to meandering river floodplains. Our varied topography is an integral part of our forest ecosystems, influencing our climate, soils, water, plant life and fish habitat (Figure 1.1). As natural resource technicians, we are often called upon to assess the topography, and one of the common elements we measure is the slope of the land. How steep is the hillside? Does the slope drain to a stream? Are there cliffs or bluffs present? Field data collected by technicians lead to informed decisions about land management activities such as providing shade for streams, building roads or trails, and prescribing timber management operations. Defining Slope Slope of the land is essentially the gradient or incline of the land. A steep slope refers to a sharp incline; a gentle slope refers to a slight incline. The steep, forested slopes in Figure 1.1 contrast with the gentler slope of the river’s path as it flows between them. Driving down a highway you may see a road sign that reads “6% Grade” or “steep grade.” The grade of the road is essentially the slope of the road. The sign in Figure 1.2 indicates that the road descends at a 6% grade or a 6 % slope. Figure 1.3. A road climbs at a gradient of 6%. The road gains 6 feet in elevation for ever...