Survey of Terrain Surface

Field Activity #1

    We were asked to conduct an elevation of surface terrain in one of the courtyard planters boxes for our first field activity. We were broken into different groups and had to learn on the fly on how to visually make 5 different landforms in the snow since it was winter time. We were asked to create a ridge, valley, hill, depression, and plain in our planters box. Upon completing these different landforms, the fun part of creating a way to sample all these landforms came into play. Sampling is a way to represent an area that you are trying to investigate. While we were sampling in a spatial perspective, this meant that we were looking at an area, our planters box surface terrain, and wanted to figure out the best way to represent our 5 different features that we created. 

    The sampling method our group choose to use was the systematic sampling method. The systematic sampling method seemed to be the right fit for this field activity, because we wanted to make sure we covered the entire surface area and was able to show the different land formations. By using a grid system we were able to conduct and capture points that would allow us to show the different landforms and there placement along with their elevation or lack there of. Figure 1 shows the grid system that we placed over our landscape area. Figure 2 also shows the grid system that we placed over our landscape, but it is from a different angle displaying the elevation better. 

Figure 1

Figure 2

    The planters box we used ended up being 122 cm wide and 88 cm long, with strings being placed across our surface terrain every 8 cm's. With only using string, thumbtacks, rulers, and a marker, our group was able to place an accurate grid over the top of our surface terrain. One problem we encountered came when we were placing the grid string over the top of the hill and ridge. It was difficult to keep the strings straight at these areas, but with a little measuring we were able to keep them in place. Another problem we ran into was dealing with the elevation and were zero elevation was at. We decided to have our zero elevation at the top of the planters box. This would allow us to show elevation above and below zero. Since the top of our planters box was absolute zero elevation, most of the starting and ending points are zero, but there were times that it was below the zero elevation when it came to the valley and backside of the ridge. The easiest way we found to record our points was to have our points spaced 8 cm apart along the string as well. With the string being zero elevation we were able to record our x and y points along with our z point, or elevation. We entered all our points into a table and then transferred them into an excel spreadsheet. This would eventually allow us to import these points into ArcMap, allowing us to configure our landscape. The string was only considered zero elevation when there was no interference from the landscape that we built. If there was interference, for instance on the hill, we then used our rulers and a small level allowing us to measure from the edge of the planters box up to the top of the hill while maintaing a level ruler. In figures 5 and 6 this technique of measuring is displayed. This may have not been the most accurate way, considering it was freezing outside and one of the rulers could have been off, but with watching the level we were able to get the points as accurate as possible. Figures 3 and 4 are what our landscape looked like before placing the grid over the top of our landscape. 

Figure 3

Figure 4

Figure 5

Figure 6

    After getting the measurements for our entire grid we came out with 180 different points. Some of these points we positive values, some of the points were negative values, and some of the points were at zero elevation. Obviously the positive points were related to the hill and the ridge in our landscape, but since no terrain is flat, there were also areas were there were small raised areas. This also had to do with that we were dealing with snow and not a hard surface to measure from. Since the hill and ridge was from the positive points, the negative points came from the depressions and valley in our landscape. Looking back at figure 4 one can see just how uneven the landscape really was when building it with snow. Our greatest negative elevation we recorded was negative 8.5 cm's. This was the lowest part of the valley that we created. Our highest point was on top of the hill we created with a point recording of positive 19.5 cm's. We did come across two points on top of the hill that were both positive 19.5 cm's, this lead us to believe that the top of the hill was relatively flat for at least 8 cm's. 

    We used the systematic sampling method from start to finish when conducting our sampling technique. Once we got through the first few grid strings, we found our groove and were able to bust out the rest of the grid with relative ease. The only issue we came across was freezing fingers and toes. We found it best that we would do three or four strings at a time then go inside to warm up before taking on more strings from the grid. This would allow the accuracy of our measurements not to be faulted from the shaking of cold hands and feet. 

    The systematic sampling method that we used relates with the sampling definition. Sampling takes only pieces from the entire area of interest and allows those pieces used in the sample to paint a relative picture of what the entire area would look like. Now of course there is no way to plot every single dip and ridge throughout our AOI, but with the systematic sampling technique we choose, we let the points do the talking. By moving the points closer from 8 cm's, to say 5 cm's, yes we would have shown more points and had a better picture. However the question when it would come to a large scale AOI would be, does the time, money, and effort justify the means. For this first field activity I would say no. Sampling is just another way to gather data over an AOI that you are looking at. It is also a very effective way to gather that data when used properly.