Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Irrigation decreases, urbanization increases monsoon rains

16.12.2009
A Purdue University scientist has shown man-made changes to the landscape have affected Indian monsoon rains, suggesting that land-use decisions play an important role in climate change.

Monsoon rainfall has decreased over the last 50 years in rural areas where irrigation has been used to increase agriculture in northern India, said Dev Niyogi, an associate professor of agronomy and earth and atmospheric sciences. At the same time, heavily urban areas are seeing an increase in heavy rainfall.

"In the rural areas, we're seeing premonsoon greening occurring two weeks earlier than what it did 20 years back as the demand for agricultural intensification to feed India's people increases," Niyogi said. "The landscape has also moved in some places from what was once a traditionally rural setting to large urban sprawls. Both of these phenomena have affected monsoon rains."

Niyogi used more than 50 years of rainfall data - spanning back to 1951 - collected by 1,803 recording stations monitored by the India Meteorological Department to determine different regions' average yearly monsoon rain totals. While the mean monsoon rainfall for the entire country remained stable, Niyogi found that rainfall averages in India's northwest region decreased by 35 percent to 40 percent from the historical mean during the past 50 years.

Analysis of soil moisture showed that before monsoon rains came, the northwest region had become as much as 300 percent wetter in recent years relative to the past 30 years, which has been attributed to irrigation from groundwater to sustain intensified agricultural production. This wetter surface causes cooling that weakens the strength of low pressure necessary for monsoons to progress into northern India.

Satellite data showed that northern India is greening sooner than it had in the past. That greening is creating a barrier for monsoons, which provide much-needed rain to replenish groundwater reserves being used for irrigation.

"In this case, you need a warm, dry surface to advance the monsoon," said Niyogi, whose findings were published in the journal Water Resources Research. "Because of increased irrigation, you now have a wet, green area, which does not allow the monsoon to reach far enough north."

Since that rain isn't reaching the region, more irrigation is needed to sustain agriculture there.

"Unless this is checked and controlled, the problem is going to become more and more severe," Niyogi said. "With more irrigation, we will have less monsoon rain. With less monsoon rain, you will need more irrigation, and the cycle will continue."

Urban areas, on the other hand, are being pounded with rain when it comes. Niyogi said there have been storms in some urban areas that drop as much as 37 inches of rainfall in a single day.

Analysis of the areas that have received increases in heavy seasonal rainfall, based on Indian Meteorological Department and NASA satellite data, showed that those areas were experiencing fast urban growth. Areas where seasonal rainfall decreased were determined to have slow or no urban growth.

"You only see these types of heavy rainfall events in those areas with heavy urbanization," said Niyogi, whose research on the urban effect was published in the International Journal of Climatology. "The more urbanization spreads in those areas, the more of these heavy rain issues we'll see and the more flooding will become a problem."

Niyogi said there are two theories on why that's happening. The first says that urban landscapes create heat, which extends into the atmosphere and energizes storms. The second theory is that pollution created in urban settings interacts with passing clouds and increases rainfall.

Niyogi said the results of his study could have land-use implications elsewhere.

"If urbanization is affecting the Indian monsoon season, it has the ability to affect patterns here in the United States," he said. "This likely isn't localized in India."

He added that India is hotter than the United States, and that may be exacerbating the issues. As global temperatures rise, other parts of the world could see similar climate changes - if they aren't already - based on how land is used and developed.

Chandra Kishtawal, of the Space Applications Center of the Indian Space Research Organization and a co-author on the papers, said he hopes the findings trigger discussions on the role of large-scale land-use planning in regulating climate change in India.

"These kinds of things are not sustainable," Kishtawal said. "They cannot continue in the long run."

The next step in this research is to examine landscapes in the United States to see if development has affected weather patterns historically.

The National Science Foundation CAREER program and NASA's terrestrial hydrology program funded Niyogi's study.

Writer: Brian Wallheimer, 765-496-2050, bwallhei@purdue.edu
Source: Dev Niyogi, 765-494-6574, climate@purdue.edu

Brian Wallheimer | EurekAlert!
Further information:
http://www.purdue.edu

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: It’s All in the Mix: Jülich Researchers are Developing Fast-Charging Solid-State Batteries

There are currently great hopes for solid-state batteries. They contain no liquid parts that could leak or catch fire. For this reason, they do not require cooling and are considered to be much safer, more reliable, and longer lasting than traditional lithium-ion batteries. Jülich scientists have now introduced a new concept that allows currents up to ten times greater during charging and discharging than previously described in the literature. The improvement was achieved by a “clever” choice of materials with a focus on consistently good compatibility. All components were made from phosphate compounds, which are well matched both chemically and mechanically.

The low current is considered one of the biggest hurdles in the development of solid-state batteries. It is the reason why the batteries take a relatively long...

Im Focus: Color effects from transparent 3D-printed nanostructures

New design tool automatically creates nanostructure 3D-print templates for user-given colors
Scientists present work at prestigious SIGGRAPH conference

Most of the objects we see are colored by pigments, but using pigments has disadvantages: such colors can fade, industrial pigments are often toxic, and...

Im Focus: Unraveling the nature of 'whistlers' from space in the lab

A new study sheds light on how ultralow frequency radio waves and plasmas interact

Scientists at the University of California, Los Angeles present new research on a curious cosmic phenomenon known as "whistlers" -- very low frequency packets...

Im Focus: New interactive machine learning tool makes car designs more aerodynamic

Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.

When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...

Im Focus: Robots as 'pump attendants': TU Graz develops robot-controlled rapid charging system for e-vehicles

Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.

Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

LaserForum 2018 deals with 3D production of components

17.08.2018 | Event News

Within reach of the Universe

08.08.2018 | Event News

A journey through the history of microscopy – new exhibition opens at the MDC

27.07.2018 | Event News

 
Latest News

Air pollution leads to cardiovascular diseases

21.08.2018 | Ecology, The Environment and Conservation

Researchers target protein that protects bacteria's DNA 'recipes'

21.08.2018 | Life Sciences

A paper battery powered by bacteria

21.08.2018 | Power and Electrical Engineering

VideoLinks
Science & Research
Overview of more VideoLinks >>>