Upstream risks spell trouble downstream
Colombia is becoming one of the largest economies in Latin America, and its accelerated development continues: it rose from the 45th place in 2013 to the 34th two years later in the World Bank’s Doing Business index.
Bogota, the country’s capital, is the most important driver in Colombian economy, contributing over 24.7% of the nation’s GDP. It is also one of its most populated cities with about 25% of the population living in or near that area. The nation is undoubtedly booming, making it crucial to keep focus on ecological matters such as water use. Over 80% of Bogota’s water comes directly from the Chingaza watershed, an overexploited ecosystem in need of better management.
Water is part of everything (even 60% of the human body is made up of it). Water is also a vital component of economic and social progress. With that in mind, the Chingaza watershed’s health plays a major role in Colombia’s sustainable development, specifically in Bogota’s growth and productivity. But, before going any further on the issues surrounding the water-stressed region, it is important to understand exactly what a watershed is.
Ever since humans started abandoning our nomadic lifestyle, we have always settled near natural waterbodies. Lakes, rivers, and streams … they are all part of their own particular watershed, which is an area that captures rainwater or snow and drains them into a common outlet. Watersheds not only collect precipitation on the surface but also beneath the earth, replenishing aquifers.
Watersheds provide water for all users downstream. Water used for industrial activities, irrigation in arable land, and for domestic use. As an ecosystem, they act as natural habitats for plants and animals of the region and are active and essential participants of the hydrologic cycle, which transforms water in a never-ending loop to maintain its availability. Beyond the water supply, watersheds also provide services that would otherwise be remedied with infrastructure: they act as water purifiers, are involved in erosion control and streamline stabilisation.
The Chingaza watershed, for instance, collects the rainfall and continues as an active participant in the next step in the hydrologic cycle: infiltration. The precipitation that falls onto the land is absorbed either by native plants or trees – in this case most likely the Sphagnum, a type of moss that is able to absorb up to 40 times its weight in water. The precipitation will seep deep into the soil, to an underground permeable rock layer capable of storing, transmitting and supplying large quantities of water known as aquifer.
Part of the precipitation won’t be absorbed but will rather become surface runoff gradually flowing into streams, lakes or rivers. At this stage, the watershed becomes increasingly crucial as it is able to regulate water flows, preventing floods or droughts to downstream areas. This is possible because the water-rich soil encountered in watersheds advances the growth of shrubs and trees that slow down runoff erosion.
Vegetation (particularly in watersheds) holds a significant place in evapotranspiration, the final stage of the hydrologic cycle. Evapotranspiration is the name given to two distinct processes that occur in plants and soil. Once water has been absorbed by plants, it is later transferred to the atmosphere by transpiration, just as water absorbed by the soil is also transmitted to the atmosphere via evaporation. And then the cycle begins once again.
When a watershed is overexploited the whole ecosystem is at risk. If there is not enough water in the soil to encourage vegetation growth, there will not be enough vegetation cover in the watershed to slow down runoff erosion, which results in floods, landslides or polluted water, as it would carry much more sediment with it.
According to the UN, within the next 10 years, two-thirds of the world’s population will live in water-stressed countries. Bogota is already part of this statistics and needs to better manage its natural resources, including the Chingaza watershed. But, how to find a solution to such a complicated issue in which many sectors of society are involved?
In this series we’ll talk about the strong correlation between watersheds and society’s development, and how Latin American countries are proposing innovative mechanisms for a sustainable approach to water management. Stay tuned to discover the consequences of an unhealthy watershed in our upcoming post.
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