Urbanized Watersheds More Sensitive To Climate Change

December 20, 1996

SAN FRANCISCO, Calif. -- A regional investigation of stream flow in urbanized areas could help planners, hydrologists and climate modelers decipher future effects of increased precipitation and temperatures, according to a Penn State researcher.

"There have been a great many studies of stream flow, temperature and precipitation, but they have all been done on undeveloped watersheds that are minimally impacted by humans," says Dr. David De Walle, professor of forest hydrology. "No one, to our knowledge, has formally looked at urban watersheds in this way."

De Walle is trying to see how urbanization affects sensitivity of stream flow to climate change. Using population data from the U.S. Census Bureau, precipitation information from the National Weather Service and stream flow data from the U.S. Geological Survey, he is looking at four regions of the U.S. -- the Northeast, Southeast, Northwest and Southwest over the past 50 years.

In each area, De Walle is comparing five urban watersheds with five rural watersheds. Analysis of data for the northeastern sector is complete.

"It is obvious that stream flow increases with an increase in precipitation, but in the Northeast, we find that with a higher population and the same precipitation, stream flow increases more," De Walle told attendees at the American Geophysical Union Conference today (Dec. 19) in San Francisco.

The study looked at areas such as Saddle River, N.J., which in 1940 had 518 people per square mile and in 1980 had 2590 people per square mile. This area is 100 percent urbanized and had an increase of 70 percent in stream flow. Rock Creek, Md., which had 648 people per square mile in 1940 and 3238 per square mile in 1980, has a 43 percent increase in stream flow. The undeveloped area of Bushkill Creek in the Poconos had a population of 8 people per square mile in 1940 and in 1980 had 39 people per square mile.

"There were some small effects on stream flow in rural areas, but nowhere near what we see in urban areas," says De Walle. "In general, there is some decrease in stream flow with increase in temperature in urban areas, but in the Northeast, this does not seem terribly important."

Increases in stream flow boost the potential for flooding and in the Northeast at least, the areas of most increase -- the most developed -- are those areas that stand to lose the most in property and human life if flooding occurs.

"If the greenhouse effect causes global warming, everyone is pretty confident that temperatures will increase, but how much precipitation will change is hotly debated," says De Walle. "We are interested in the effects of precipitation because it is the least reliable of the two variables in the climate models."The global climate models can provide regional predictions, so De Walle will dedicate the final year of this two-year project, funded by the U.S. Environmental Protection Agency, to the other three regions and to comparing how climate change will effect stream flow in all four regions.

Penn State

Related Climate Change Articles from Brightsurf:

Are climate scientists being too cautious when linking extreme weather to climate change?
Climate science has focused on avoiding false alarms when linking extreme events to climate change.

Mysterious climate change
New research findings underline the crucial role that sea ice throughout the Southern Ocean played for atmospheric CO2 in times of rapid climate change in the past.

Mapping the path of climate change
Predicting a major transition, such as climate change, is extremely difficult, but the probabilistic framework developed by the authors is the first step in identifying the path between a shift in two environmental states.

Small change for climate change: Time to increase research funding to save the world
A new study shows that there is a huge disproportion in the level of funding for social science research into the greatest challenge in combating global warming -- how to get individuals and societies to overcome ingrained human habits to make the changes necessary to mitigate climate change.

Sub-national 'climate clubs' could offer key to combating climate change
'Climate clubs' offering membership for sub-national states, in addition to just countries, could speed up progress towards a globally harmonized climate change policy, which in turn offers a way to achieve stronger climate policies in all countries.

Review of Chinese atmospheric science research over the past 70 years: Climate and climate change
Over the past 70 years since the foundation of the People's Republic of China, Chinese scientists have made great contributions to various fields in the research of atmospheric sciences, which attracted worldwide attention.

A CERN for climate change
In a Perspective article appearing in this week's Proceedings of the National Academy of Sciences, Tim Palmer (Oxford University), and Bjorn Stevens (Max Planck Society), critically reflect on the present state of Earth system modelling.

Fairy-wrens change breeding habits to cope with climate change
Warmer temperatures linked to climate change are having a big impact on the breeding habits of one of Australia's most recognisable bird species, according to researchers at The Australian National University (ANU).

Believing in climate change doesn't mean you are preparing for climate change, study finds
Notre Dame researchers found that although coastal homeowners may perceive a worsening of climate change-related hazards, these attitudes are largely unrelated to a homeowner's expectations of actual home damage.

Older forests resist change -- climate change, that is
Older forests in eastern North America are less vulnerable to climate change than younger forests, particularly for carbon storage, timber production, and biodiversity, new research finds.

Read More: Climate Change News and Climate Change Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.