Lake modeling

Sean Hogan and Ryan Waller

Introduction

Our project is to develop a software tool to model the amount of phosphorous in the lakes in central Maine. According to Elaine Tiejen, author of the China Lake Syndrome the element phosphorous is the primary limiting factor determining the rate of plant growth in most Maine lakes. Phosphorous is a naturally occurring element and can be found in rocks and rainwater in low concentrations. However, much greater concentrations are found in eroded soil, road dust, fertilizers, septic wastes, and detergents. Tiejen states that phosphorous usually accounts for roughly one per five hundred parts of a typical freshwater plantUs total mass. A small increase in phosphorous can stimulate massive plant growth, usually in the form of algae blooms. Thus, a working software model of this process will be valuable to environmental scientists because they will have access to unlimited simulations. In addition, the software will allow the scientists to test the integrity of their model. In short, anomalies in the model will either provoke its revision or lead to new discovery.

The mathematical model we will be using was designed by Rockhall and Chupra, and was provided by Professor David Firmage. Professor Firmage implemented Rockhall and Chupra's model in the form of an Excel spreadsheet, but found that it was not an ideal implementation. Typically, the students in Biology 493 use the model for their semester analyses of a nearby lake. The results of their analyses are then published and distributed to local government agencies, as well as state agencies involved with environmental protection. The new implementation we develop will hopefully be a vast improvement over the previous one. In addition, we hope the biology 493 students will have a more powerful tool to test results and run simulations with. The actual model we will be using entails coefficients and variables that will be accessible to the user to manipulate, but the actual equations of the model will be hidden from the user. All coefficients and variables will need to be checked for erroneous entries, such as negative areas or out of bound entries. Coefficients: There are approximately seventeen coefficients that are considered in professor Firmage's model, some include forested land, logged land, and roads near by. These coefficients have upper and lower bounds that will have to be determined individually by the user or entered in as a default setting.

Areas:

The areas of the coefficient variables will need to be entered by the user some include the volume of the water inflow and the area of the lake surface. The areas are used to determine the per capita in years for the shoreline for seasonal use and year round use. The per capita measurement is determined by the calculation

(person/unit) *
(#of days (seasonal or year round)/365) * 
(units seasonal or units year round)

The per capita is then used to calculate the area P loading with the calculation from the total mass loading.

Mass:

the area multiplied by the coefficients determines the calculations of the individual masses. Once the mass calculations have been formulated then the high and low percentages of phosphorous content can be determined for each coefficient. Then the phosphorous content of the lake can be determined within a upper and lower bound.

We plan on implementing our project in the form of a Java applet. There are a number of reasons why we choose the Java programming language. First, the software can be stored and compiled on the web, which promotes accessibility for Colby students and faculty, as well as anyone interested in this subject matter outside of Mayflower Hill. Secondly, Java has an extensive graphics class that will enable us to create a graphics intense project. Third, Java offers a variety of powerful features that will allow us to produce the best software tool possible. Our project will present us with many design considerations over the course of the semester. Our first consideration is to create a fast and user friendly environment in which parameters can be changed easily, while being displayed or tracked. Other considerations are plotting multiple graphs or just single graphs. This project must posses all of the necessary attributes of a good software tool. It must be robust, readable, re-useable, and functional.