Computing for Sustainable Water

Where is the Chesapeake Bay Watershed?

The Chesapeake Bay Watershed is the largest estuary in the United States and borders the Atlantic Ocean. Its land mass extends over parts of six Eastern states (New York, Pennsylvania, Maryland, Delaware, Virginia, and West Virginia) and the District of Columbia (Washington D.C.). It covers 64,299 square miles (166,534 square kilometers).

Why is the restoration and sustainability of the Chesapeake Bay Watershed important?

Nearly 17 million persons live and work within the Chesapeake Bay Watershed today and its population continues to grow. With this population growth and the effects that it has on the streams and rivers and eventually the Bay itself, there has been a measurable decrease in the health of the Chesapeake Bay. According to the Chesapeake Bay Foundation, Bay health has poor grades, varying from year to year, depending on changing environmental conditions. For the Chesapeake Bay Watershed to improve and maintain a healthier condition, concerted action is needed.

How is the health of the Chesapeake Bay measured?

The health of the Bay is typically measured in terms of the level of dissolved oxygen throughout the Bay. Scientists take measurements over the course of the year and at numerous locations around the Bay. The areas where the level of dissolved oxygen is too low to sustain aquatic life and vegetation are deemed anoxic. Areas that are marginally better are deemed hypoxic. The goal of restoring and sustaining the Chesapeake Bay is to significantly reduce the size of the anoxic and hypoxic areas returning the Bay to a healthier condition.

What causes a decrease in the levels of dissolved oxygen?

Nutrients and sediment flow into the Bay from the land areas surrounding the Bay. These nutrients, such as nitrogen and phosphorus, lead to the growth of algae. This is commonly seen as a green film on the water’s surface. As these algae die, decompose, and sink to the bottom, they remove oxygen leaving the water with insufficient levels of oxygen to support life.

Where do nutrients come from?

Although a small level of nitrogen and phosphorus enters the Bay through natural processes, the majority is the result of human activity. Agriculture contributes nutrients through farming methods, fertilization of the land, and tilling of the soil. Land development—the built environment—turns open land into impervious surfaces where rainfall and snow melt run off the surface rather than being absorbed into the soil. Waste treatment facilities provide for some nutrient removal, but many homes within the watershed use in-ground septic systems that eventually leach into the ground and reach stream and creeks flowing to the Bay. Manufacturing, power generation, and other human activities likewise contribute to nutrients flow.

What has prompted action in the Chesapeake Bay Watershed?

Action to restore and sustain the Bay has had a long, though unsuccessful history. However, in May 2009, President Obama signed an Executive Order mandating the restoration and sustainability of the Chesapeake Bay Watershed. By this action, the various states and local communities will receive limits on the levels of nutrients they contribute to the Bay. Known as Total Maximum Daily Loads of nutrients and sediment, these communities must develop plans to curtail the impact of human activities on the levels of nutrients and sediment reaching the Bay.

What kinds of actions might be taken?

There are various methods that can be adopted to reduce nutrient and sediment loads reaching the Bay. These are collectively known as “Best Management Practices (BMPs).” For example, farms can leave buffer areas between planted fields and bordering streams. They can minimize their use of fertilizers, plant cover crops in the winter (to absorb excess nutrients), and provide for the proper removal of animal waste. Municipalities can provide for separate storm water runoff systems and increase the frequency of street cleaning. Even individuals can affect change through household practices (reducing lawn fertilization, planting trees and shrubs) and limiting automobile driving. These types of actions are called non-point sources because they collectively contribute to the nutrient and sediment problem but are not individually measurable. Manufacturing, power generation, and other industrial contributors are point sources and these are regulated through existing policy and laws.

How will the Computing for Sustainable Water project address the problem?

This project will, via a detailed simulation model of the entire Chesapeake Bay Watershed, test the impact of a large number of Best Management Practices (BMP)over a 20-year period. The proposed BMPs will be tested individually and in combination to assess their potential to effectively reduce the flow of nutrients and sediment into the Chesapeake Bay. Each of the various BMPs is expected to reduce the overall level of nutrients flowing into the Bay to some extent. However, scientists have no way of knowing in advance exactly how effective each might be. The project will provide an answer allowing policy-makers to choose those BMPs that will have the greatest impact.

How will the results of this project help other watersheds and catchments?

The Chesapeake Bay Watershed is but one of over 400 major watershed/catchment systems globally. It is not unique in facing the challenges of population growth, increasing urbanization, and the challenges of changing environmental conditions. The results to be reported from this project can inform policy-makers worldwide as to best practices to employ to restore and sustain the globe’s precious water resources. More importantly, perhaps, information from this simulation can help citizens make better choices and help the private sector identify opportunities for new products, services, and processes that reduce nutrient flow.

What is the difference between the Computing for Sustainable Water project and the Computing for Clean Water project?

The Computing for Sustainable Water project is studying how changes in human activities could help improve the quality of watersheds, critical for sustaining life and food sources. The Computing for Clean Water project is trying to develop less expensive water filters so that it would be more practical to produce clean drinking water from poor water sources.