Climate change and land use data to predict watershed impact

Date:
January 27, 2022
Source:
Florida State University
Summary:
Researchers studied the Chesapeake Bay watershed to evaluate the
combined effects of changes to climate and land use on runoff and
pollutants in a rapidly developing watershed that is a tributary
to the bay.



FULL STORY ==========================================================================
When rain falls, it picks up pollution from streets, farms and other
humanmade features as it winds toward the ocean.


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In the Broad Run watershed of Loudon County, Virginia, runoff travels
through an increasingly urbanized landscape before reaching the Potomac
River and the Chesapeake Bay. In 2000, fewer than 170,000 people lived
in the county. More than 400,000 people live there now.

The impact of that urbanization is the focus of a new study led by Nasrin Alamdari, an assistant professor of civil and environmental engineering
at the FAMU-FSU College of Engineering, with colleagues from Virginia Polytechnic Institute and State University, Ohio State University and
the U.S. Geological Survey (USGS). The research was published in the
Journal of Cleaner Production.

The work is the first study in the Chesapeake Bay watershed to evaluate
the combined effects of changes to climate and land use on runoff and pollutants in a rapidly developing watershed that is a tributary to
the bay.

"There have been individual studies regarding urban activities
or population growth, but the joint impacts of climate change and
land use changes have not been assessed at the local level," Alamdari
said. "Using new modeling procedures, we can accurately reflect the impact
of urbanization and climate change on hydrological processes." With a new model developed by the team, the researchers found that average annual
runoff in the watershed is expected to increase by at least 26% when considering land use policies that prioritize agricultural conservation
and the less extreme climate change scenario in the model. Runoff could increase by as much as 67% if historical trends in urban growth continue unabated and the worst-case climate scenario they considered comes to
pass. As runoff increases, pollutants such as suspended solids, nitrogen
and phosphorus also increase.



==========================================================================
The researchers used data from two global climate models that had been
adapted for the Broad Run watershed to develop their model. They looked
at trends in agricultural conservation, forest conservation, growth
management and historical trends to develop a series of land use change scenarios using the Chesapeake Bay Land Change Model developed by USGS.

"Water resources management and hydrologic design have long relied on the principle of hydrologic stationarity, which assumes that future conditions
will be statistically similar to that observed in the historical record," Alamdari said. "These models don't account for climate change and urban development and how they might affect runoff and pollutants in rapidly developing watersheds." An active watershed restoration effort is
currently underway in the Chesapeake Bay watershed. A so-called total
maximum daily load limits the nitrogen, phosphorus and sediment discharged
into bay tributaries from municipal wastewater, urban stormwater and agricultural sources. These pollutants cause a variety of impacts in
the bay, including eutrophication, harmful algal blooms and loss of biodiversity and aquatic habitats.

A comprehensive understanding of changing landscape conditions can help
urban planners and environmental policymakers choose more sustainable
and resilient watershed restoration strategies.

The results of the study are transferable to other rapidly developing
areas.

The modeling framework will help policymakers and other interests identify
and evaluate mitigation strategies that will be useful in watersheds
with similar conditions.

"This information is timely, considering the schedule of the total maximum daily load and the outcomes could have broad impacts on the Chesapeake
Bay watershed," Alamdari said. "The methodology can be extended to other regions similarly impacted by urban growth and the results from this
project can be broadly applicable to other metropolitan areas discharging
to sensitive water bodies." The National Science Foundation, the Virginia Agricultural Experiment Station and the National Institute of Food and Agriculture supported this research.

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written by Trisha Radulovich. Note: Content may be edited for style
and length.


========================================================================== Journal Reference:
1. Nasrin Alamdari, Peter Claggett, David J. Sample, Zachary M. Easton,
Mohammad Nayeb Yazdi. Evaluating the joint effects of climate
and land use change on runoff and pollutant loading in a rapidly
developing watershed. Journal of Cleaner Production, 2022; 330:
129953 DOI: 10.1016/ j.jclepro.2021.129953 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/01/220127141618.htm

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