Evaporation at Western Pond as Compared Seasonally

Our project is a study of the evaporation rate of water from Western Pond. We are including lab tests that test the effects of solar radiation, salinity, and wind on evaporation. We want to know what conditions increase evaporation. Are any of our variables factors in the evaporation rate of water? We want to be able to answer these questions and link our findings to some real life application.
We should be able to determine, after this study, what bodies of water lose higher volume of water due to evaporation, and why. We may also be able to determine Western Pond's contribution to the water cycle.

I. Introduction

Our group is interested in studying Western Pond, specifically the rate of evaporation of water from the pond under different environmental conditions. We think it would be interesting to compare the evaporation rate of Western Pond to evaporation from a large body of water i.e. the ocean. We might possibly be able to determine how much Western Pond actually contributes to the water cycle.
We intend to collect readings of air and water temperature, and using models and equations to estimate the average rate of evaporation from the pond under these different conditions. We have also added wind velocity into the equation. We plan on using the average wind velocity each day and seeing if that has any effect. Based on previous instruction we hypothesize that evaporation rates will be higher under conditions with relatively warmer air and water temperatures, higher wind velocities. We are also going to test evaporation rates under different conditions in the lab. We will test solar radiation as a factor that, we hypothesize, increases evaporation. Salinity is another factor that we would like to test in the lab. Higher salinity should increase the evaporation rate. Also we are hypothesizing that a smaller surface area will evaporate slower. More particles on the top will be exposed to solar radiation. Solar radiation is what causes evaporation. If they are more spread out too, they will have a smaller affinity to one another.
Evaporation methods are used to purify water and dispose of hazardous waste (Filtration & Separation p.429). If we are able to determine the evaporation rates the data could be used in other studies to determine how healthy the pond is under different conditions. Someone would be able to determine how much harmful waste evaporates from the pond. At certain times of the year, under different environmental conditions, the pond might cycle out pollution naturally and be healthier.

II. Relevance

We have read several science journal articles that deal with evaporation from varying experimental angles. A Sweden-based engineering firm studied methods for hazardous waste disposal involving evaporation (Filtration & Separation p.429). Some scientists have studied evaporation rates in different types of soils (Soil Science Society of America Journal pp.341-346). Studies have been done that determines that greater surface area increases evaporation yields (Solar Energy pp.261-266). A group of scientists has found evidence that evaporation acts as a cooling method for bodies of water, much like the act of sweating cools the human body (Science News p.69). Winds hinder rainfall, and push evaporated moisture out of areas that need water (Natural History p.48-49). According to Dr. Klink of Miami University, wind could be a great factor in the evaporation rate. By moving clouds, wind can increase or reduce solar radiation, directly affecting evaporation. In a study of evaporation in oat and rye crop fields, scientists determined that there is seasonal difference in evaporation rates (Journal of Soil and Water Conservation pp.263-268). Two interesting studies dealt with deforestation in tropical environments. Levels of forestation clearly are important in regards to evaporation (World Development pp. 53-65) & (Ecological Economics pp.107-123). In a related study, a group tried to calculate the levels of evaporation in fields that have been slashed and burned for agriculture (Journal of Hydrology pp. 293-305). Another study calculated the evaporation over a 44-day period from the forest floor (Journal of Hydrology pp. 97-113). Salinity is also a factor we are interested in testing. An article in Compton's Electronic Encyclopedia describes the way in which salt is extracted from water by evaporation. The encyclopedia also states that salt raises the temperature of water. That is why salt is put on icy roads in the winter. Since salt increases temperature, it would also increase the evaporation rate of water. All of these studies are related to evaporation and its effects on the natural world.
All of these studies' results can be implemented in the real world. We can take their data and convert it to many aspects of society. Hazardous waste can be disposed of more efficiently and effectively. Farmers can tell how much water they should expect to lose from their soils due to evaporation. Companies like fish hatcheries or water treatment plants can determine evaporation rates of different-sized tanks and basins. Perhaps in the future we will use evaporation to cool off things such as houses or cars. Even seasonal evaporation numbers can be important to companies, which are looking at locating in certain areas of the country or world.
III. A. Materials and Methods (our group study)

Our group proposes to set up five evaporation pans at varying locations around Western Pond. Two pans will be placed in open spaces, two in wooded spaces, and one next to the boathouse. Daily, we will measure the water level in the pans. Any loss or gain will be attributed to evaporation or the water cycle(rain). We will also place three temperature probes; one in an open area, one in the woods, and one in the classroom. In addition to these observations, Professor John Klink will provide us with daily air temperature, wind velocity, and humidity measurements taken from the Oxford area. Our group will also be making observations from five control pans located in Boyd Hall. We plan to record the same sets of data from these pans. We will test other variables in our control set-up. For two weeks we will measure evaporation in the classroom in Boyd. For the next two weeks will measure evaporation rates from pans placed on the pavement directly behind Boyd. This test is designed to give us some idea of the effects of solar radiation on evaporation. For the following two weeks we will add salt to the water in our control pans, to see if salinity affects evaporation. For the remaining week before the end of the study, we will test the effect of wind on evaporation.
Combining these sets of observations we hope to estimate evaporation rates of Western Pond in different conditions. Our experiments will be statistically sound because of the frequency of data collections, and number of variables accounted for. The use of control pans helps us compare unstable to stable environments.
Materials used in our study will be pans to house the water, chicken wire to cover the pans from foul play (swans, people, etc), and digital temperature probes to record temperatures. In the lab we will be using salt to increase salinity in the pans. A small floor fan will be used to simulate wind in the lab.

III. B. Materials and Methods(class lab)
For the in-class lab we propose to set up five pans in Boyd Hall simulating different conditions. These pans will be set up as follows: one control pan (room water temperature, no wind), one pan (room water temperature, with wind), one pan (outside), one pan (with salt), and one pan (smaller surface area than control pan, room water temperature, no wind). 24 hours prior to the lab, we will take measurements on all of the pans. The day of the lab we will disclose these numbers to the class. We will then have them hypothesize which variables will have which effects on the rate of evaporation. Each lab group will measure each of the pans. They will measure the current water level, and sharing this with the rest of the class, come together and make conclusions about their data.
The class is not directly involved in our group study, but this lab should give them a better understanding of our project. After this lab they should be able to name factors that affect water evaporation, and which ones have the most effect. We hope they will better understand the relevance of our project.
We plan on measuring the evaporation around Western Pond starting this week. It will most likely be Friday October 1. We will measure everyday up through November 19, the Friday before Thanksgiving break. The rest of the time will be spent examining data developing conclusions, and writing the lab report.

Table for Student Lab
Tray OneControl Tray TwoSalt Tray ThreeOutside Tray FourWind Tray FiveSurface Area
Day One
Day Two

Our Lab Chart

Tray one Water Level Air Temp Water Temp Humidity Wind Velocity
Day 1
Day 2
Day 3

(sample chart) one data sheet for each tray.

Cited Works

"A Drought's Unyielding Cycle", by Kenneth Kunkel; Natural History Jan. 1989 pp 48-49
"Do Clouds Provide a Greenhouse Thermostat?" Science News Aug. 1 1992 p.69
"Evaporation from young secondary vegetation in eastern Amazonia", by D. Holscher, T.D. de A. Sa, T.X. Bastos, M. Denich, and H. Folster; Journal of Hydrology volume 193 1997 pp. 293-305
"Forest floor evaporation in a dense Douglas fir stand", by M.G. Schaap and W. Bouten; Journal of Hydrology June 1997 pp. 97-113
"Spatial Variability of Evaporation along Two Transects of a Bare Soil" by R.J. Lascano and J.L. Hatfield; Soil Science Society of America Journal March 1992 pp. 341-346
"Surface energy balance partitioning over rye and oats cover crops in central Iowa" by J.H. Prueger, J.L. Hatfield and T.J. Sauer; Journal of Soil and Water Conservation Third Quarter 1998 pp. 263-268
"The Paths to Rain Forest Destruction: Crossnational Patterns of Tropical Deforestation" by Tom Rudel and Jill Roper; World Development Jan. 1997 pp.53-65
"Third-world debt and deforestation", by James Kahn and Judith McDonald; Ecological Economics Feb. 1995 pp. 107-123
"Waste Not Want Not - With the Help of Evaporation" Filtration and Separation June 1997 pp. 425-429
"How Water Evaporates and Boils." Compton's Electronic Encyclopedia

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• Evaporation (2/6/03) [ Contributor: -Section: ]
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