A traditional water gauge in the Las Ciebas River under the Guayabo bridge on the outskirts of Neiva is complemented by a sensor suspended from the same bridge which sends water level data over radio waves.
Crédito: Courtesy of FAO
Colombian River Basin Passes the Test of El Niño and La Niña
Por Constanza Vieira *
Risk prevention measures with active community participation have reduced the threat of flooding and water shortages in the Colombian city of Neiva.
NEIVA, Colombia, May 14 (Tierramérica).- Engineer Patricia Gómez is leading a training workshop for a group of 11 men at the fire station in Neiva, the capital of the department of Huila in southwest Colombia.
Several of the firefighters are wearing their red uniforms. They seem relaxed, but are attentively watching the large flat screen on which Gómez is explaining how to read the indicators from the disaster warning system.
Gómez is demonstrating the Integrated Hydrometeorological Monitoring and Early Warning Network for the Las Ceibas River Basin (RIMAC), a high-technology system for disaster prevention in real time.
The Las Ceibas River is both a source of life and a source of disasters.
The river is the sole source of water for the city of Neiva. But deforestation and slash-and-burn agriculture, a traditional peasant farming practice that wreaks havoc on the Andean mountain slopes, have led ever larger amounts of sediments to run into the river, deteriorating water quality and increasing the risk of landslides.
When the river overflows, it floods the poor neighborhoods of the city, located on the riverbanks.
At the training workshop on RIMAC, Gómez shows the firefighters how the effects of the heavy rains in the city earlier in the day are reflected on screen.
A table of indicators, produced with data sent every five minutes by sensors installed at different points along the river basin, shows that the rainstorm resulted in the highest water level in the river so far this month: 2.36 meters.
The RIMAC network currently encompasses eight monitoring stations, but will eventually extend to 22, as part of an inter-institutional project coordinated by the Food and Agriculture Organization of the United Nations (FAO) that has been underway for four and a half years.
The data gathered by the sensors is compiled at the station at the public Surcolombiana University in Neiva.
The firefighters are responsible for monitoring the system 24 hours a day. If an event occurs, they inform the mayor, the only person authorized to declare the level of the alert.
Gómez reminds the firefighters what to tell communities about the meaning of a yellow alert: “What I didn’t do when the situation was normal, I do when there is a yellow alert: I get prepared.” Orange alert: “I am waiting to hear what the authorities say. I am prepared.” Red alert: “I hope to God that no one is out there…”
FAO engineer Humberto Rodríguez does not hesitate for a moment when asked about the main achievements of the Las Ceibas River Basin Project, which he directs and of which RIMAC forms part.
“It has reduced the risks faced by the communities living on the riverbanks when the Las Ceibas River overflows,” he told Tierramérica.
The project involves the municipal and departmental governments, the regional environmental authority, and the Public Utilities Companies of Neiva (EPN).
“The warning system we have established allows for a constant flow of information on the river’s water level. This has been complemented by a community radio system that keeps us informed of the situation of the river basin,” said Rodríguez, a specialist with more than 30 years of experience.
“We also have a system of manual rain gauges. We communicate by mobile phone with the owners of the fields where the gauges are installed, who have become greatly committed to the project,” he added.
In other words, community members are actively participating in risk prevention. Some 600 families live in the rural areas of the river basin, but the most vulnerable sectors of the population of the city of Neiva, which has 295,000 inhabitants, are also involved.
The firefighters are just learning to use the new equipment. Their main criticism so far is that the system connected to the fire station in Neiva does not emit a sound to signal a warning, as one of them pointed out to Tierramérica.
“That is something we can change,” said Rodríguez when Tierramérica mentioned it to him.
During the time that the project has been underway, the burning of farmland has decreased by 90 percent, according to FAO estimates.
When the project started, between 300 and 400 hectares of land were burned annually, resulting in greater sedimentation and higher risks downriver.
This has decreased to one to four meters at most, according to current reports.
The EPN employee responsible for the water intake at the Guayabo bridge, on the outskirts of Neiva, recalls a time when the river’s high sediment content led to readings of 8,000 to 9,000 nephelometric turbidity units (NTU).
The turbidity of drinking water should not exceed five NTU, according to the World Health Organization. In the Las Ceibas River, the last reading was around 4,000 NTU, which means that the sediment level has been cut in half.
"Less soil is being washed into the river by surface runoff,” said Rodríguez.
The change was achieved through simple techniques that also form part of the project’s implementation, such as persuading the community to adopt better agricultural practices, reforestation, the use of organic fertilizers to improve crops, and bio-engineering to prevent landslides, through the creation of terraced steps in mountainous areas anchored with tropical bamboo (Bambusa guadua).
One of the keys is to “convince the people that this is ultimately their last chance to offer an environmental service to Neiva,” namely by improving the quality and quantity of water supplied to the city, Rodríguez explained.
Since the project’s success lies in linking the 600 rural families with the urban population of Neiva, the project has established a Watershed Board. “It is perhaps the only one in Colombia that really works,” commented Rodríguez.
The Board is made up by the project’s partner institutions and delegates from the community. It meets two or three times a year to discuss community concerns and proposals for improvement.
During the most recent drought associated with the El Niño/La Niña-Southern Oscillation (ENSO) phenomenon, the river’s flow in Neiva dropped to between 2.6 and 2.3 cubic meters a second, but there was no need for water rationing, while in other parts of the country, the water supply was interrupted.
Tierramérica was able to confirm this on the streets of Neiva. “That’s the way it used to be,” commented a local resident, referring to a time when the city was left without water.
Before, during the times of drought and El Niño, “the river basin was like a flaming torch. Today the areas burned have been reduced considerably. This means that the conditions for the regrowth of vegetation have improved,” said Rodríguez.
ENOS is a periodic climate pattern that occurs across the tropical Pacific Ocean and affects the weather throughout the world. In Colombia, its warm phase, El Niño, causes droughts, while its cool phase, La Niña, brings heavy rains.
In Neiva, La Niña is also felt differently now. Last year was the rainiest in a decade in the river basin, with over 2,900 mm of precipitation.
Yet the river flooded only once, in November 2010, when its level rose by almost three meters, and not a single neighborhood of Neiva was affected. This demonstrates that the river basin is beginning to perform a regulating function.
* This article was produced with support from FAO.