a Biosphere 2 blog by lily house-peters

  • An acequia in Curcupe, Sonora
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What are cenotes? Sinkholes in the Yucatan, Mexico

Looking into a cenote in Cuzama, Yucatán, Mexico (photograph courtesy of Ashley Coles)

“ABYSMAL AND DEEP – A translation of the Mayan word “dzonot,” which was changed to “cenote” in the 16th century when the Spanish conquistadors discovered the strange and magical sinkholes, of which there are an estimated 6,000 on the Yucatán peninsula.

In January, 2012, I had the opportunity to travel to the Yucatán peninsula to attend and present research findings at the annual Conference of Latin Americanist Geographers.  After 3 days of attending engaging presentations and workshops highlighting social and natural science from across Central and South America, I spent my final day in the Yucatán visiting Cuzama, a small, Mayan town home to a number of stunning cenotes.  I toured 3 cenotes and as someone deeply interested in both the natural, geomorphological processes that create different forms of water occurrence (in this case deep sinkholes filled with freshwater) and the storied myths that accompany these unique places.

This left me wondering about cenotes….

(photo courtesy of Ashley Coles)

Water availability on the Yucatán peninsula is extremely interesting; the Yucatán peninsula is porous limestone and there are no visible rivers!  Because the peninsula is limestone it is water soluble and thus caves form where freshwater collects.  Freshwater then collects in these sinkholes, creating cenotes.

Although cenotes are formed through a natural process of the dissolution of limestone (as I briefly describe above), the story of where cenotes are located and why is a slightly more complicated story.  A high density of cenotes exist in one portion of the Yucatán peninsula which is the rim of the Chicxulub Crater.  In fact, the crater was discovered due to the high density circular alignment of the cenotes!  The Chicxulub Crater has since been extensively mapped and has been dated; scientists believe the crater is 65 million years old and is the result of a meteorite impact.  Not just any meteorite impact however – this meteorite is associated with the mass extinction of the dinosaurs (or the Cretaceous-Tertiary extinction event).

Cenotes also hold a sacred place in Mayan religion and mythology: for the Maya, cenotes represent the entrance into the underworld.

Acequia Culture: Community Management of Surface Water in Arid Lands

An acequia in Curcupe, Sonora, Mexico

In environments around the world where surface water is limited, communities have developed methods to manage and share scarce water resources so that agriculture and other livelihoods remained possible.  One form of surface water management that can be found in different iterations around the world is the acequia.  In the northern portion of the state of Sonora, Mexico, just south of the Arizona/Mexico border, the environment is harsh – little rain for most of the year, scorching temperatures, and mountainous terrain.  Historically, these factors limited irrigated agriculture to small areas of land directly adjacent to rivers and streams.  To move the water onto the fields, communities built and managed canal systems, called acequias, that controlled where the water flowed.

The history of the acequia culture in Sonora is particularly interesting due to Sonora’s unique status in the history of Mexico.

“The periphery of the periphery” (Historian and anthropologist, Tom Sheridan, referring the marginal status of Sonora in Mexico’s history and development)

In comparison to the rest of Mexico, Sonora has a unique history of economic and water-resources development.  The long standing marginality of the region meant that until very recently the area was never subjected to the full height of colonial exploitation or capitalist penetration.

Before the recent widespread introduction of wells into the watershed (which has occurred only during the last twenty years or less) the only topological location where irrigated agriculture was possible was in the narrow alluvial floodplains.  The climate, characterized by limited precipitation and hot temperatures, also limits irrigation, but a long history of building and maintaining community-managed acequias has allowed farmers and ranchers to utilize the limited surface water to sustain livelihoods based on floodplain agriculture and ranching activities.

There is evidence that as early as 1723 there existed a ‘común de Curcupe’ (Curcupe is one of the towns located along the Rio San Miguel, in Sonora, Mexico) that exercised community control over irrigated lands lying along the Rio San Miguel.  The farmers in the floodplains of the Rio San Miguel rely on the riparian forest, mainly the willow and cottonwood trees, to increase their resilience to floods, including retarding channel cutting, limiting erosion, and trapping floodwater sediment.

 It was Jesuit missionaries, not Spanish colonists, who pioneered initial settlement in Sonora and later acted as agents for the dissemination of European agrarian techniques and technologies.  The Jesuit presence in Sonora prevented the evolution of large private estates and land-holdings during the 17th and 18th centuries, very unlike the history of land tenure development in neighboring Chihuahua state.  Although the Jesuits were expelled from Spanish lands in 1767, they left behind the legacy of community control of land and water resources, a system which still exists today.

However, over the last two decades, new forms of intensive agricultural development in Sonora have focused on the international export-market rather than on local markets and subsistence forms of production.  Since the passage of NAFTA (North American Free Trade Agreement) in the early 1990s, the expansion of foreign capital in the region, and a shift in Mexican governance models to neoliberal strategies that devolve natural resource management and monitoring to already financially strapped municipalities, fundamental shifts are occurring in the social and economic systems in the region.

Will the widespread introduction of the groundwater well wipe out acequia culture?  Or will acequia management remain, perhaps the water flowing through the canals will be a mix of surface water and ground water from wells? These are questions that our research team is currently trying to answer. Stay tuned….

Bangalore, Where Have Your Lakes Gone?

In 2008, I traveled to the southern India mega-city of Bangalore.  The primary goal of the trip was to examine the condition of water resources available to people living in mostly informal housing settlements on the periphery of the city.  A city of over 10 million people and counting, Bangalore is rapidly expanding.  People flock to the urban center from the surrounding rural areas as well as from all over southeast Asia in hopes of landing well-paying jobs in the IT sector.  In the peripheries of the city, one is immediately struck by the stark contrasts between communities living in clusters of houses made primarily of cardboard and scrap metal and the palatial, glass-walled structures complete with perfectly manicured lawns that house familiar companies such as Dell and IBM.

Along the periphery of the city our research group wondered:

  • Where (and how) did people in these communities procure drinking water?
  • Did the city deliver water through pipes to them?
  • Did the community have access to a well?

The answer to these questions, we found, were primarily that no, the city did not deliver water (due to shortages of available water as well as lack of infrastructure, such as pipes to the periphery of the city) and no, the communities could not afford to dig expensive wells.  So, how did people in these communities get water? We still wondered.  The answer – two sources: urban lakes and private water distributors. Private water distributors are  very common throughout cities in Latin America, Africa, and Asia; it is not an uncommon scene to see residents, unable to depend on a public water supply and lacking financial resources to drill private wells, line the streets in the peri-urban fringe waiting to fill colorful buckets with water from expensive, private sources, mainly tankers. But urban lakes? This piece of the water puzzle was fascinating.

Bangalore, it turns out was once known for its lakes, 144 in fact.  Bangalore was once water rich, a landscape dominated by lakes. But urban development and (mis)management of water resources has left a mere 16 remaining lakes, many of which are now used as holding containers for sewage.  In fact, as I stepped from the bus on my first day visiting the communities, I was overwhelmed by a putrid smell.   The gravity of the water management crisis in Bangalore, India, became immediately apparent.  Once potable, reliable sources of drinking water for the local community, the two lakes spanning the visible distance, the culprits of the smell, were inundated with raw sewage, overflow from the local sewage plant which is unable to handle the increased waste produced by the rapidly expanding population.

These lakes are in fact unusual, not for their highly polluted state, but because they exist at all.  As the urban population has rapidly swelled in Bangalore, space has become a hot commodity.  Lakes have quickly disappeared, filled in with concrete to become football stadiums, sports complexes, a bus depot, a medical complex, and numerous dense apartment housing complexes.

What happens when floods stop occurring?

Recently, I have been thinking about what happens to the forested river corridors (also called riparian areas) of the desert when winter floods become less common.  As unusual as it is to think about forests in the desert, it is equally uncommon to think about winter floods in the desert. But these floods are critical to the soil, plants, and animals that call desert forests their home.  These riparian areas are vital habitat to many species including migrating birds. In fact, the US/Mexico border region contains one of the top ten birding destinations in the world!

 

Humans also depend on these forested areas for a wide range of livelihood activities, such as ranching, agriculture, mining, recreation, and tourism.  Thus, when the biophysical dynamics of these forests are altered, peoples’ activities must also change to adapt to the new conditions.

So,  what happens to both ecosystems and livelihoods when winter flooding decreases?

 

The above photo is of the San Pedro River, which if you notice is devoid of water!  The trees in the photo are mostly cottonwoods, a keystone species in the riparian forests in semi-arid environments.  These trees are vital for maintaining biodiversity, as well as acting as a first line of defense against flooding and erosion. This is especially important for farmers, whose land is adjacent to the river.  Farmers use living cottonwood and willow trees to construct fences to help defend their farmland.  Additionally, these trees help to cycle nutrients, which keeps the soil fertile and the water in high quality.

Living Fence Rows adjacent to the Rio San Miguel in Sonora, Mexico

Importantly, though, the cottonwood trees require winter floods for reproduction. Thus, with fewer winter floods, cottonwoods are unable to reproduce, leaving only mature trees with no young trees in the forest.  This leaves the forest susceptible to disease and fire.  Meaning, the riparian forest is less resilient in a world with reduced winter flooding.  Over the last 30 years, we have recorded a reduction in winter floods, and future climate model predictions show that this trend may continue.

So, what will happen to our riparian forests? How will we adapt? These are very important questions and we are only beginning to learn the severity of their consequences and how to find solutions that protect both biodiversity in these special ecosystems and the livelihoods of the people who depend upon them.

Wondering about the Ocean


Normally, my attention is focused on freshwater ecosystems, but this month I had the exciting opportunity to travel to Brazil to attend and present a scientific paper at the 14th World Water Congress. The meeting was held in Porto de Galinhas, a small town located on the Northeastern Atlantic coast just south of the equator.  Although two prominent rivers flow through the large city of Recife about an hour’s drive from Porto de Galinhas, while in these places, all I could think about was the sea.  And this left me wondering about the ocean.

Standing on a coral reef at low tide on the edge of the South American continent staring out into the massive expanse of the Atlantic Ocean, I was faced with an ecosystem so completely opposite to that which I am used to studying (the water scarce rivers of the desert), that I became extremely curious about the myriad creatures living in that great expanse and how they might be affected by changes in climate and land use in coastal Brazil.  Normally, I focus on how changes in land use, climate, and urbanization impact the structure and function of the forests that line the rare rivers in deserts, but faced with these turquoise waters, I couldn’t help to wonder how the impacts differ, or if in fact some are the same.  How resilient (defined as the ability to withstand stress without collapsing) are our oceans?  What makes them resilient? Are they more vulnerable to human action as climate changes?  What measures are being taken to protect this coastline and the marine environment?  Look for the answers to these questions in an upcoming post.

As I wandered along the reef, I also thought about the role of tourism in such a fragile ecosystem.  One on hand, visiting the reef and experiencing its beauty in person is a powerful experience, one that fills the curious person with many questions, and serves as an effective tool for educating the public. On the other hand, however, the daily trampling of these highly biodiverse but very sensitive places speeds up the process of destruction and degradation of the corals.

In addition to wondering about freshwater, I plan to continue to post on this blog about marine environments. Check back soon for answers to some of the questions I have posed.  Take a look below at the photos from the Brazilian coast.

 

Rivers in the desert?

The San Pedro River flows through the dry, desert landscape of Northern Mexico and Southern Arizona.  The flowing water provides an oasis to hundreds of types of birds, plants, mammals, and insects.  Who ever said the desert wasn’t chock full of biodiversity?

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