Geoscience student identifies water resources for volcano communities


Riley Mulhern, an undergraduate student in geophysics at Wheaton College, Illinois, recently spent six months volunteering with Nuevas Esperanzas as part of Wheaton’s HNGR program. He spent many days in the field gathering data as part of Nuevas Esperanzas’ ongoing work on water supplies. Here is how he described a day in the field:

You make your way up the side of the Telica volcano on well-worn trails winding through fields of bean and corn ready to be harvested. The route is steep and rocky so now and again you stop to catch your breath and take in the incredible view of Nicaragua’s central plains behind you. The climb is made harder by the weight of your pack. In it you have about a kilogram of table salt, two one-liter pitchers, several syringes, a probe for measuring water chemistry, several empty bottles, a water turbidity meter, GPS and camera, rain jacket, lunch, and three liters of your own drinking water. It is also 32 degrees and the sun is fierce today.

You carry on, sometimes through small groves of banana or mango trees, welcoming the shade. Soon you begin to descend into a small ravine and are met by the sound of a trickling stream. The water comes into sight momentarily and you find yourself in front of a scene quite unlike the bean fields you just passed through. On your left a tall bank of whitish rock is speckled with neon-green sulfur crystals and is spewing hot steam into the air. Blue and yellow butterflies flutter around the banks of the clear, bubbling stream. A wall of red, tan, and grey boulders, many covered with bright green moss faces you on the other side of the gully, and a high green canopy overhead, full of chirping parakeets, closes you in. This is where you stop, and where the work begins.

Many of my days looked like this during my time with Nuevas Esperanzas. I volunteered for six months, during which I spent much of my time researching the valuable water resources on the northern slopes of the Telica volcano. The trickling stream described above is one of the most important sources of water for the 415 people living in the communities of Agua Fria and El Caracol. It is the people’s main, reliable source for washing and bathing, watering livestock and, in difficult times, even drinking. The stream is fed by a series of small springs. While the stream itself may be easily contaminated as it is unprotected, the springs often remain excellent sources of clean water. A day spent here in the rainy season might lead you to believe that these communities have plenty of water. However, during the five months of the dry season you will undoubtedly change your mind. As many of the springs are recharged by rainwater alone, they are liable to drying up during the difficult summer months. In the absence of rainwater harvesting capability, families must either walk further for water or turn to the unprotected, contaminated stream.

This is why I have all that equipment in my pack. We need it to discover how much water is available to these communities and whether it is being used effectively. To find this out, many questions needed to be asked. Where is the water coming from? Where is it going? What is the quality of the available water? What are the various sources fit for? How are they currently being used? Answering these questions allows us to make better decisions about how to improve access to water for the families in this area. We discovered that the water from the canyon is only accessible within a relatively small geographic area and is lost if not used right away. We recently completed a 3.7 km pipeline to deliver clean drinking water from one of the mountain springs to communities below. Their water sources were contaminated with arsenic and without the pipeline the water from the canyon was reabsorbed into the ground before it reached them. Although water on the slopes of Telica is very limited, the pipeline project shows that creative solutions allow what is available to benefit a wider population than just the immediate surrounding communities. This potential provided a strong additional motivation for our research.

The salt, pitchers, syringes and probe allowed us to measure the stream flows through a method called salt-dilution gauging. A concentrated salt-water solution is released upstream and the probe is placed downstream. As the salt reaches the probe, the electrical conductivity (a property of water directly influenced by dissolved salt) increases sharply before slowly returning to normal as the salt passes. The resulting data is used to calculate an accurate stream flow in liters per second. Repeated measurements over time give an idea of how the quantity of water fluctuates between rainy and dry seasons.

As well as measuring the quantity of the water, we also test its quality. The turbidity meter shows how clear the water is. Water with a lot of sediment suspended in it will have a very high turbidity. Using the multi-parameter probe we measure properties such as temperature, pH, electrical conductivity, and dissolved oxygen which provide more information about the water quality. We also took samples from every spring along the northern slope of the volcano and at various locations along the stream bed to be sent for laboratory analysis.

None of this work results in concrete solutions or visible results in the way that a pipeline bridge spearing through the treetops or a new rainwater harvesting tank right next to someone’s home do. But the data we collect gives us a better understanding of the water resources and needs in these communities. It helps us continue to work with and help them as effectively as possible. This is the motivation that drove me up the sunbaked slopes of the Telica volcano with that heavy pack day after day.


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