Guest Essay by Kip Hansen
Last January, I wrote about the curious case of Lago Enriquillo in the Dominican Republic, the “Dead Sea of the DR” – a super-saline lake that lies about 140 feet below sea level in the east of the country right up against the border with Haiti. The lake has been growing since 2003, flooding local villages and overwhelming local agriculture.
In my previous essay, I discussed the possible causes of the growth of the lake and dismissed the silly idea, put forth by the New York Times’ Randal Archibold, that the cause was their one-note bogeyman, global climate change. The major cause of flooding in this part of the country is the long-term deforestation – the image above shows the flood areas (in red) down in the valleys – when the tropical storms come and bring inches of rain per day, it all runs down the rugged, denuded hills into the streambeds, into the rivers and eventually into the sea at Barahona. The major “cuenca” – Dominican for watershed – of the region is the Yaque Sur. The map below shows the current flooding of Lago Enriquillo
My wife and I spent many years in the DR and for a while focused our efforts in the rocky valley – a gorge really – formed by Rio Las Cuevas (in the red box on the map), where we represented a humanitarian organization that funded a series of irrigation projects in the villages there in partnership with a local organization – Sur Futuro. All projects included an element of reforesting the hills with native trees or a permaculture mix of native trees and commercially valuable fruits and bushes (such as coffee), under-storied with subsistence vegetables.
It is a truly awesome sight to see these small dry valleys, with tame little rivers or even small creeks running down them, turn into raging maelstroms of churning water and stone such as happened with Hurricane Noel in 2007. There had been a lovely little horse ranch on an island in the rocky dry riverbed of the Yaque Sur, a green oasis amidst the sea of grey stone – a house, barns, corrals and pastures. After Noel, the entire island was simply gone. We could not get up the Rio Las Cuevas valley for almost six weeks.
The direct cause of these massive floods, with almost flash-flood intensity, is the historic deforestation of the surrounding mountains. The cure is reforestation – a cure that will take generations.
In my essay last year, I posited that the underlying cause for the rising water in Lago Enriquillo was this very deforestation which, despite some protests to the contrary, is ongoing and continuing due to the increasing population of the area brought about by the increase in successful agriculture and their never-ending demand for wood to use for cooking fuel. This rather offhand assertion lacked a certain finesse and did not answer all the variables involved in a more complex problem — I offered it in good faith mostly to offset the ridiculous idea that Global Climate Change was to blame.
I am a real fan of actual discussion in the Comment Section – to me, this is where the understanding comes about. Not just for the readers, but for the authors – hopefully – as well. As the discussion evolved, it struck me that the areas north and east of Barahona had blossomed in the previous ten years or so due to irrigation water supplied to agriculture from the upper Yaque and the large dam near Padre Las Casas. This water was supplied the old fashioned way – in irrigation canals.
Yes, you see, connect the dots – increasing population around Lago Enriquillo due to increased agriculture – agriculture made possible by irrigation, water brought in by ditches – from – you guessed, the Yaque Sur dam.
Digging more than a little bit reveals that INDHRI – the Dominican Water Resources Institute – had been running water from the Yaque Sur watershed into the Enriquillo watershed from which there is no outlet.
Those of you with quick minds can already sense the situation. Hold on to that thought.
After many days, I went on to some other project. Revisiting the essay last month, I discovered that a reader “J. Gonzalez” had left a critical comment . Here’s the gist of his complaint:
– “INDRHI believes the problem was the broken dyke at the Yaqui del Sur, which allowed fresh water to rush into the lake, causing the levels to rise and also the salinity to drop. …. There are many, many connections between the Yaque del Sur and the lake.”
– “But then canals from the Yaque del Sur were constructed to keep water levels steady and the salinity at such a rate that marine life could continue to survive. But the lake surface area never expanded at the rate it did after one of the Yaque del Sur dykes broke following the storms in 2003 — Claudette, Odette, etc.”
– “The Army Corps of Engineers and a group of scientists from NY came here to study the lake and said the cause was inconclusive, but likely due to increased rainfall and the broken dyke. Whether the increased rainfall is due to climate change is up for dispute. In my opinion, it seems unlikely, especially in that time span.”
The purpose of this essay is to expand on my original investigation as to the causes of the ever-expanding lake. (Note that the lake did not seem to continue to grow in the year 2013 according to the press in the DR – I have not found any information about 2014.) I appreciate J. Gonzalez’s comment as it spurred me to deeper investigation.
There have been quite a few in depth studies of Lago Enriquillo:
As I pasted this in, I realized that it is in Spanish. I’ll have to use it as is, with a bit on on-the-fly translation. [Over 13% of Americans speak Spanish as a first language in their homes – even more speak Spanish as well as English. In Florida, there are Walmart stores in which all the signage is in Spanish.] The chart shows the seven most important studies done in recent years with a summary of their findings on causes and solutions.
As for Sr. Gonzalez’s first point “INDRHI believes the problem was the broken dyke at the Yaqui del Sur, which allowed fresh water to rush into the lake” – I could find no mention in any of the studies or in the Dominican printed news media, or on the INDHRI website, which would indicate that INDHRI (or anyone else) believed that a broken dyke had “allowed fresh water to rush into the lake”. One of the studies in the chart – CIBIMA-UASD (2011) – found damaged infrastructure or faults in irrigation canals – might be a contributing factors, along with seismic activity, erosion and sedimentation, and correlation between Lake Sumatre (in Haiti) and Lago Enriquillo. The study in which the Army Corp of engineers participated did not mention a broken dyke incident. More about “canals” is our next point:
Sr. Gonzalez’s second point is: “But then canals from the Yaque del Sur were constructed to keep water levels steady and the salinity at such a rate that marine life could continue to survive. But the lake surface area never expanded at the rate it did after one of the Yaque del Sur dykes broke following the storms in 2003”. Again, nothing in the seven reports or the DR news media supports the assertion that some one broken dyke was or is responsible. Many of the reports speak of the poorly built and poorly maintained irrigation canals as a possible problem – the canals “leak” water into the surrounding soil. One of the reports reported in the media was on a study that used satellite data to “see” subterranean water flows and reported that there were subterranean streams and flows into the lake from all parts of the watershed, which is exactly what one would suspect for a below-sea-level lake.
[The datum marked “unlikely” is over ten meters higher than the expected range…such an increase would have been extraordinary and had it actually been true, would certainly be mentioned in narratives about the current rising water levels, which it is not. There is no mention of such levels occurring in the mid-1960s.]
Note that Sr. Gonzalez mentions the fact that canals were intentionally used to bring fresh water from the Yaque Sur watershed into Lago Enriquillo to replenish the shrinking lake – and ever more saline lake – in 2003….in other words, bringing water from the Yaque watershed into the Enriquillo watershed was a solution…and one that I think has had unintended consequences. Prior to 2003, there was national and international concern that Lago Enriquillo was shrinking, and becoming more saline, threatening the native fishermen’s livelihoods and the endangered salt water crocodiles that live in the lake. A scheme was carried out to bring water from the Yaque Sur to Lago Enriquillo, via canals, based on the long-term shrinking trend from about 1965.
Let’s look at the watersheds:
The first image is the official INDRHI map, showing both the YaqueSur and the Enriquillo watersheds, accompanied by a satellite photo with cross-hatching (sorry, it’s a bit dark), and my road-map overlaid with some elevation numbers at critical points and a big red line approximating the divide between watersheds.
This greatly magnified topographical map clearly shows the canals leading to the lake. Even more canals were built since the 1990s to bring irrigation water to the vast fields of bananas and avocado groves. All the water is brought in from the Yaque Sur watershed. Every drop of water brought into the Enriquillo watershed that does not evaporate or get exported as moisture in agricultural products, ends up in the lake. There is no other exit.
What other possibilities are there? The seven studies list the following as possible suspects:
1. The plain-jane theory: ingress of water (rain water) above the soil’s retaining capacity, resulting on more water into the lake. 5 of 7 studies mention this.
2. Increasing rain due to increased evaporation from warming oceans – somehow coupled to reduced evaporation from the lake.
3. Increased rainfall resulting in increased freshwater input from springs. See #1.
4. Deforestation resulting in more runoff coupled with increasing sedimentation due to erosion caused by deforestation.
5. Ingress of irrigation water to the watershed – excess of irrigation.
6. Five hurricanes and tropical storms in the 2007-2008 period.
7. Seismic activity which may have either opened up more freshwater springs or opened a connection allowing water to drain from Lake Sumatre in Haiti into Lago Enriquillo.
A summary report supported by the European sources, by Reynaldo Payano and Ojilve Medrano, concludes: “The increased water level of Lake Enriquillo is probably due to an increasing number of events of high precipitation during the past few years higher than the capacity of the soil and groundwater inputs of the Etang de Saumâtre Lake (Lake Sumatre).” And recommends more study. (The chart of seven studies is from their report). Please note however that none of the reports contains actual annual local precipitation numbers.
So, here is my conclusion:
1. There is more water coming in than going out (via evaporation). See 2 thru 5 below.
2. Increased rainfall,
3. coupled with increased deforestation which reduces the capacity of the soil to absorb and retain water
4. coupled with increased sedimentation of the lake during heavy, tropical-storm and hurricane rainfall events, caused by erosion which is caused by continuing deforestation, which results in raised water levels.
5. Uncontrolled and unregulated ingress of water from the Yaque Sur watershed by way of canals – like leaving the water running, even if “just a little”, into a stoppered bathtub.
Why don’t I list water running in from Lake Sumatre? This graph show clearly that the water level in Sumatre increases along with that of Lago Enriquillo…if it was truly water from Sumatre “leaking” into Enriquillo, it seems to me that Sumatre would either shrink or remain level while Enriquillo rises. I am, however, no hydrological expert.
What lesson can we learn from all this?
We can learn that climatic issues are very complicated and simply blaming any and all situations on Global Climate Change just because they have a factor that is related to the weather is almost always wrong.
Scientists can work very hard on an issue, study the various aspects of a problem with heavy-duty statistical packages, satellite imaging and image parsing software, ground piercing radar, and other sophisticated tools, and still, different groups of scientists, studying the same problem, can come up with different results and conclusions. Seldom does one study resolve difficult issues. Sometimes even many studies do not resolve an issue, as we find here.
Sometimes an unsupportable “scientific idea” – a proposed cause of a problem – gets injected into the popular culture of the locale involved – such as the “broken dyke” theory (which did show up in political attack Opinion Section columns in the DR – but was never mentioned in any news reports or scientific studies) – and then remain as part of the popular culture, despite study after study which finds the cause to be nonexistent or not true.
In the case of Lago Enriquillo, in spite of the relationship between lake levels and incoming water, none of the major studies actually attempted to measure, or even estimate, in any way, the water being imported into Cuenca Enriquillo from the Yaque Sur – even though they were attempting to understand where the extra water was coming from. This strikes me as an obvious oversight – or political correctness, not wishing to blame a government agency [INDRHI] for causing the problem.
It will be interesting to see how the lake fares over the next couple of years. I’ll try to write an update next year.
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Author’s Comment Reply Policy: This essay is not about AGW or Climate Change or the Climate Wars, so let’s not have comments about those topics.
Salt-water crocs, however, may be appropriate.
I prefer civil conversation.
I have links to all the studies, most of which are in Spanish, for those who want them.