Rainfall, wind and temperature can have wide-ranging effects on Chesapeake Bay habitat, water quality and fish and shellfish populations. While all plants and animals can adapt to periodic changes in environmental conditions, scientists cannot predict with certainty how the region will respond to the prolonged periods of extreme weather that have been linked to climate change.
The amount of rainfall the watershed receives can affect river flow, or the amount of fresh water flowing into the Chesapeake Bay from its various tributaries. Under normal weather conditions, fresh water flowing from rivers and streams makes up about half of the Bay’s entire water volume. But extremes in rainfall—whether too much or too little—can have varying effects on the Bay ecosystem.
During large rain events:
During periods of little rainfall or drought:
A lack of precipitation can also disrupt groundwater supplies. A number of watershed communities need groundwater to provide drinking water and irrigate crops.
Wind can disrupt or reinforce the Chesapeake Bay’s two-tiered flow of fresh and salt water—with fresh water flowing near the surface of the Bay and salt water flowing near the bottom of the Bay—by mixing these waters and sometimes reversing the direction of the flows.
Wind can also raise or lower surface water levels:
Because the Chesapeake Bay is so shallow—with an average depth of about 21 feet—it has a relatively small capacity to store heat over time. As a result, the Bay’s water temperature fluctuates from 34 to 84 degrees Fahrenheit during an average year.
Changes in water temperature can affect the reproduction and behavior of fish, crabs and oysters. Higher than average water temperatures can also affect underwater grasses:
Temperature also plays a critical role in determining the amount of dissolved oxygen in Bay waters. The cooler the water, the more oxygen it can hold. Therefore, Bay waters can hold more oxygen during the winter than during the summer.
For Chesapeake Bay restoration to be a success, we all must do our part. Our everyday actions can have a big impact on the Bay. By making simple changes in our lives, each one of us can take part in restoring the Bay and its rivers for future generations to enjoy.
To lessen the impacts of severe weather on the Bay, consider reducing stormwater runoff. Install a green roof or rain garden to capture and absorb rainfall; use porous surfaces like gravel or pavers in place of asphalt or concrete; and redirect home downspouts onto grass or gravel rather than paved driveways or sidewalks. You can also offset the impacts of climate change by reducing your greenhouse gas emissions, whether it is by using electric or manual lawn mowers or by driving the Bay-friendly way.
You can keep track of weather in the watershed with the Chesapeake Bay Interpretive Buoy System (CBIBS), which is operated by the National Oceanic and Atmospheric Administration (NOAA) and which collects real-time meteorological, oceanographic and water quality data from more than 10 locations up and down the Bay.
Grant funding will build coastal resiliency in states affected by Hurricane Sandy.
A University of Maryland assessment shows the hurricane had “ephemeral” impacts on water quality.
Preliminary data show the superstorm has done less damage than Hurricanes Isabel, Irene and Tropical Storm Lee.
From spilled sewage to shellfish bans, we are tracking the weather's effects on the watershed.
34% of Bay waters met standards for dissolved oxygen; some oyster and grass beds healthy despite conditions.
Annual average river flow to the Bay during the 2012 water year (October 2011-September 2012) was 52 billion gallons per day. This is 21 billion gallons per day less than 2011 and close to the 51 billion gallon per day average flow from 1937-2012.