Lab 1: Sand Box Terrain Model

Introduction

Welcome to my blog which will be used for the 2015 Fall Semester Geospatial Field Methods course offered at the University of Wisconsin-Eau Claire and taught by Dr. Joseph Hupy of the Geography and Anthropology Department. This blog will serve the purpose of portraying the course work we will be covering in class. Then be able to be show in a portfolio style blog to showcase my skills I have developed over my years at the University.

For more information on myself or other blogs I have put together show casing my geospatial capacity please visit my website at http://drakebortolameolli.weebly.com/

Our first assignment in the Geospatial Field Methods course was to create a Digital Elevation Surface model using a 4 foot by 4 foot box and sand we gathered down on the bank of the Chippewa River in Eau Claire, Wisconsin. Split up into six even groups of three we would have to build ourselves a landscape in the box and with the materials provided figure out how to create a surface model which could then be uploaded into ArcMap at a later time.

The purpose for this assignment was to gain knowledge on basic styles of surveying, be able to work in a team and to be able to think critically as we did not have any written instructions on how to go about doing our survey.

The Environment

Working in a group of three, myself, Alyssa Krantz and Evan Geurts, we worked in pretty perfect weather conditions. It was around 4pm when we started, slightly cloudy and a slight breeze, our area of study was located directly under the foot bridge crossing over the Chippewa River (north side) on the University of Wisconsin-Eau Claire’s campus (image 1).

Image 1: Study area under walking bridge at the University of Wisconsin-Eau Claire (Eau Claire, Wisconsin)

Methods

After transporting all the materials to our area of study, we set up our 4 foot by 4 foot box. None of the sides of the box were connected to the other, so for the first thirty minutes we tried to create a level surface between the boards (will be further addressed in the discussion section below)Image 2. The materials we had to use for this project included; 4 boards to create our box, fishing line, a leveler, marking flags, tape and lots of sand and rocks.

Image 2: Attempting to create an even level between different segments of the sand box

After setting up the box, something that took much longer than expected, we began creating our land features (image 3). Inside the box we were to include a ridge, hill, depression, valley and plain (image 4). Using our hands we dug through the sand creating the required features. We had to remove some rocks from the area because they were interfering with our landscape, while others stayed in the box to give it a more rough style landscape. The sand was difficult to work with, as it was pretty dry, making it very tough to create hills and ridges.

Image 3: Creating the landscape inside our box

Image 4: Inside our box we have several features including a ridge, hill, depression, valley and plain

The next step after creating all our features was to figure out the elevation of our terrain. The way we set up our box nothing was above boards. In order to make it simpler to work with we decided to treat our terrain as if it were the ocean floor, thus creating the board level as sea level.

Next, we had to come up with a way to record multiple points of elevation. We were not allowed to write on the boards so we put a layer of tape all around the box so we could have something to write on. We then measured 10 centimeter increments and placed tick marks along the boards. Since our boards were not a perfect square we ended up with 12 tick marks on one axis and 13 tick marks on the other. Each tick mark corresponded to the origin, in number and letter terms A1 was our origin (images 5-7). We used numbers and letters while writing down our data to make it simpler to record, but when put into an excel file we changed it to distance from the origin. 

Image 5(left): Using the orange string and tape we were able to create a grid across the entire box
Image 6(middle): The completed grid spanned over the entire box
Image 7(right): The B represents the second row of grid lines, the adjacent axis will have numbers

Using bright orange string we created a grid over our area of study, we forgot to bring scissors with us to cut the string so we had to tape the ends and then carefully loop around to the next tick mark. After creating the grid we had 156 crossing locations. Using a meter stick we measured the distance in centimeters down from the string to the ground point and recorded that on to a piece of paper, which would later be entered into an Excel Spread sheet (Image 8).

Image 8: Using a meter stick we recorded the distance from the orange string (sea level) to the top of the sand feature

In order for our data to be correct we had to put negative numbers in front of all our data numbers, otherwise we would have inverted data, meaning our highest points on the surface model would then show up as the lowest points in a digital model (image 9). This data will be used in the next part of the exercise when we import it into Arc and attempt to create a 3D model of our data.

Image 9: The data measurements (cm) from the sand box have been put into an excel file. The negative numbers represent below sea level. The numbers highlighted in green represent distance from the origin (A1). 

Discussion

Overall, this project did not seem to be like a geography class assignment, but instead a real world application on a small scale model. We learned about basic survey techniques, got to visualize how you can turn a sandbox creation into numbers which can be used to create a 3D map. Lastly, this assignment was a great way to not only work on team building but also problem solving and critical thinking.

We did manage to come across a few difficulties while working. One was trying to get our boards to be even with one another. We started off by using a leveler to make sure each individual board was level, but what we did not take into consideration was making sure all the boards were level with one another, so by time we got to the final board we had about a 2 inch height difference. This was definitely the longest section of the assignment.

The only other problem we came across was when we were measuring the distance from the string to the terrain feature. Every once in a while the string would stretch when touched so we would have to compensate or try to pull the strings tight again to continue with the accurate measurements.

Conclusion

The project I would say turned out to be a success. We achieved our goals of creating a terrain model in the sands of the Chippewa River, create a grid over the area, get accurate measurements of the terrain and put all our results into an easy to read Excel file.

Some may say it was not real surveying, but the task was not to use the correct style of surveying but instead be able to come up with our own accurate way using what little tools we had to work with.