How Does Urbanization Change Storm Patterns and Rainfall Amounts?

Two Purdue University studies show that urbanization changes storm patterns and rainfall amounts, highlighting the need for urban planning and infrastructure design that considers how the landscape will affect the weather.   (Image: via   pixabay  /  CC0 1.0)
Two Purdue University studies show that urbanization changes storm patterns and rainfall amounts, highlighting the need for urban planning and infrastructure design that considers how the landscape will affect the weather. (Image: via pixabay / CC0 1.0)

Two Purdue University studies show that urbanization changes storm patterns and rainfall amounts, highlighting the need for urban planning and infrastructure design that considers how the landscape will affect the weather.

In two separate papers, teams led by Dev Niyogi, Indiana state climatologist and professor in the departments of Agronomy and Earth, Atmospheric, and Planetary Sciences, studied storm patterns over the coastal megacity of Mumbai, India, and the mountainous city of San Miguel de Tucumán, Argentina, to determine how urban development affected storms in those regions.

The Mumbai study was done in collaboration with the Indian Institute of Technology Bombay, while the study in Argentina was done with the University of Alabama in Huntsville.

The researchers expected to see that Mumbai’s added heat and buildings significantly disrupted storms. But they expected to see little impact in San Miguel de Tucumán since the terrain around the city is rugged, which likely makes the storms turbulent before they reach the city.

In Mumbai, Niyogi said, the urban landscape disrupted rainfall, creating pockets and ribbons of rain that would intensify downpours in some parts of the city. Mumbai and other Indian cities have experienced significant flooding in recent years, possibly exacerbated by the way the cities affect storms.

Some cities have experienced significant flooding in recent years, possibly exacerbated by the way the cities affect storms. (Image: via pixabay / CC0 1.0)

Some cities have experienced significant flooding in recent years, possibly exacerbated by the way the cities affect storms. (Image: via pixabay / CC0 1.0)

The researchers also found the storms organize themselves over the city in clusters. This organization showed that meteorologists should focus on small, 100-kilometer-squared areas with rain gauges or satellite images to best model future storms.

The study, published in Nature — Scientific Reports, used satellite data to track storm patterns and model the ways in which Mumbai was altering those patterns.

Niyogi said the results highlight the need to understand how sprawling urban landscapes will affect severe weather, helping inform flood monitoring efforts and future critical infrastructure decisions:

San Miguel de Tucumán’s urban development also influenced regional rainfall patterns, according to results published in the journal Geophysical Research Letters.

Satellite data and models showed that urbanization resulted in 20-30 percent less precipitation downwind of the city and an eastward shift in precipitation upwind. Again, Niyogi said the effect cities will have on rainfall changes needs to be taken into account before large-scale developments continue in the mountain regions where water is already a scarce resource:

Despite differences in each storm studied, precipitation in Mumbai and San Miguel de Tucumán both fell into fairly predictable patterns — ribbons or pockets of heavy rain in India and a skirting of the city in Argentina.

Provided by: Purdue University [Note: Materials may be edited for content and length.]

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