Voyage of Kiri blogger Kristian Beadle sees firshand the effects of water from the sky impacting water on the ground.
Location: At the river mouth in Mulegé, a town on the fourth largest oasis in Baja. The green river winds past palm trees before opening into the Sea of Cortéz.
Conditions: Humid with the buzz of crickets and mosquitoes. Bougainvilleas and trees filter the morning light.
Discussion: "The water was up to here," said Saul Davis, pointing above his head at a mark on the wall. "There was mud everywhere." Davis is the charismatic owner of a small market in Mulegé, a town completely flooded in September 2009 by Hurricane Jimena. Although a drop in windspeed reduced it to a Category 1 as it made landfall in Baja (media interest also fizzled as a result), it arrived with massive rainfall. Out of the 3,200 inhabitants, nearly half suffered property damage, and many lost everything they owned.
The Mulegé area receives rain from summertime storms in contrast to the Vizcaíno Desert, which is in a meteorological shadow. Backed by a broad range of mountains, the Sierra de la Giganta, rain falls into 16 watersheds that ultimately converge into the Mulegé River. When a hurricane hits, imagine opening 16 faucets at full capacity into a small sink.
On the evening we arrived, there wasn't much hint of devastation. We had dinner at a restaurant by the beach and watched the full moon rise over the water. Alyssum was beside herself with the sight of this oasis and the many shades of green. After 1,000 miles of dry desert, this was our first stop in a real vegetated area.
Most of the town is set in the narrow river valley. Thanks to its colorful one-way streets and architecture, Mulegé is about as cute a town as you can find in Baja, and many ex-pats from U.S. and Canada now call it home. One we met was Jimmy Christopher, a retired Californian and Rotary Club member, who manages a small medical clinic, funded by the local Rotary Club, with volunteer doctors from all over the world. They also support the fire department with equipment donations and their yearly fundraiser, a sport fishing competition. In the wake of the flood, a mosquito spraying campaign was run to prevent dengue fever, a problem in other flooded cities. "The spray was natural, from chrysanthemum extract and really kept the mosquitoes under control," Christopher said proudly.
The town center is on higher ground, about 1 mile from the ocean, but the siren call of the blue ocean and green river vistas lured growth toward the riverbanks and oceanfront. Memories of past floods were forgotten.
"Before we got here in 1982, there had been two floods on record," Christopher, a retired Californian and Rotary Club member, told me. "The floods of 1914 and 1955. Then since 2006, we had three floods — almost one every year! I'm starting to get tired of rebuilding the roof and everything else."
The greatest damage occurred in the narrowest part of the valley, which is spanned by the highway bridge. Several people told us the water level came as high as the bridge, which hard to fathom if you look at a photo of it, at right. Floodwaters completely engulfed houses and knocked down hundreds of palm trees. Seven months later, many houses still lay abandoned, in complete disrepair.
Why the frequency of floods now after so many quiet years? "I think it's global warming," said Christopher. Others shrugged and said, "It's happened before."
Whether climate change can affect hurricane activity — through increased CO2 and higher sea surface temperatures — is an active topic of scientific debate, which I will have to cover in the next post. For now, suffice to say that hurricanes are complex beasts that emerge from tropical storms. There is agreement on one issue: excess greenhouse gases in the atmosphere will increase the intensity of storms (in general) and especially rainfall, since warmer conditions allow more water vapor to be sucked from the air. The higher risk of flooding is especially problematic for coastal areas because of storm surge. Researchers analyzing streamflows in large basins and GHG trends conclude that so-called 100-year floods likely will become more frequent.
How can we deal with the prospect of more floods in a warmer world? In Mulegé, the government is currently relocating the school and many households to higher ground. Seems like a logical step, but some residents wonder if that is a realistic solution. "If we currently live by the river, do we have to abandon our homes? Plus, that's where the tourists want to go, that's where business is," said Ricardo Castillo, the president of the citizen group Al Resgate de Mulegé (To the Rescue of Mulegé).
The group wants a long-term solution for the community; they propose flood control measures such as check dams to slow the deluge of water in the tributaries leading into the Mulegé river. "We will petition the federal government," Castillo said with conviction.
The question is one of engineering solutions versus managed retreat (i.e. hard versus soft approaches). Whereas managed retreat is politically unpopular, engineering solutions are often costly. They require money upfront, have unforeseen ecological impacts and may not ultimately work. In the name of progress (and pride) modern society has almost always favored the latter (see Ryan Blitstein's Miller-McCune story from last October). After centuries of battle, the Dutch are still fortifying their coast with levees (aka dikes). In the United States, the issue of levee failure has reached national proportions.
Ecological engineering, a field gaining momentum to tackle climate challenges, may be a promising middle ground — rebuilding wetlands to absorb storm surge, reducing impermeable pavement and increasing green spaces to absorb water into the ground. Should the solutions be hard, soft or medium?
The answer to this sensitive question affects the lives of the weary folks in Mulegé and other places susceptible to floods whether it's Arkansas forests, the French Riviera, southern China or my homeland of Brazil, where more than 100,000 are currently homeless due to floods.