Understanding Survey Grids

Background and Objectives:

The objective of this exercise was to gain a better understanding of survey grids and construct a survey grid in a sandbox landscape. A secondary objective was to understand how different sampling techniques may be used in field research. Spatial sampling involves determining how measurements will be taken across a given study area. Three sampling types were discussed

Random: Random samples are taken across the study area in order to reduce bias

Systematic: Samples are taken at systemic intervals throughout the whole study area

Stratified: Samples are taken within small groups to portray a portion of the whole study area

This exercise was completed outdoors between 1:00 and 4:00 pm with a temperature of 3 degrees Fahrenheit

Methods:

To construct our survey, the following items were used

1. Meter Stick
2. Thumb Tacks
3. Measuring Tape
4. String

To begin, the perimeter of the sand box was measured using the measuring tap. Each side was found to be 114 centimeters in length. A systematic sampling method was choosen, and each side was divided into 19 separate 6 centimeter segments. Thumb Tacks were used to mark off each six centimeter segment. String was then woven in between the thumb tacks to create a grid. An X and Y axis was assigned to the grid, and the X/Y coordinates for each section were recorded in a spreadsheet.

The next step involved measuring the height above "sea level" to obtain a Z coordinate for each section. For the purposes of this assignment, sea level was considered to be the string that made up the grid, with features below the string being below sea level. Using a meter stick, this height was measured to the nearest half centimeter and recorded for each section and entered into a spreadsheet.

Results:

Our survey consisted of 361 individual data points. According to the data obtained, the average height of our sandbox landscape was approximately 6 centimeters below sea level. The highest point just made contact with the string and was recorded to be at sea level. The standard deviation is 2.38 meaning that the vast majority of measurements fall within 2.38 centimeters of the average.