Hydropower Dams Can Harm Coastal Areas Far Downstream
By Paula Ezcurra and Octavio Aburto
Thousands of hydroelectric dams are under construction around the world, mainly in developing countries. These enormous structures are one of the world's largest sources of renewable energy, but they also cause environmental problems.
Hydropower dams degrade water quality along rivers. Water that flows downstream from the dams is depleted of oxygen, which harms many aquatic animals. The reservoirs above dams are susceptible to harmful algal blooms, and can leach toxic metals such as mercury from submerged soil.
We wanted to know whether dams also impact river systems farther away, at the coastlines where rivers flow into the sea. So we performed a natural experiment comparing four rivers along Mexico's Pacific coast — two that are dammed and two that remain free-flowing. We found that damming rivers has measurable negative ecologic and economic effects on coastal regions more than 60 miles downstream.
Feeding or Starving Coastlines
We studied four river outflows along the Pacific Coast of Mexico in the states of Sinaloa and Nayarit. Two of these were from the San Pedro and Acaponeta rivers, which are relatively unrestricted, with over 75% of their flow unobstructed.
The other two outflows came from the nearby Santiago and Fuerte rivers, which have over 95% of their flow retained in reservoirs. In addition to restricting water flow, these reservoirs trap sediments — over 1 million tons per year along the two rivers combined.
In unobstructed rivers, sediment flows downstream and is eventually deposited along the coast, helping to stabilize the shoreline and sometimes even to build it up. We found that this was happening along the free-flowing Acaponeta and San Pedro rivers.
However, because the sediment from the dammed Santiago and Fuerte rivers is no longer carried downstream, wave action takes over at the coast. At the mouths of these two rivers, we found that waves were eroding up to 33 hectares of combined land — equivalent to about 62 football fields — each year, with widespread ecologic and economic effects on the surrounding regions.
The dammed Fuerto and Santiago Rivers show greater erosion where they reach the Pacific coast than the free-flowing San Pedro and Acaponeta rivers. Images at right show coastline changes during the two periods: blue indicates land accretion, red indicates erosion.
Ezcurra et al., 2019., CC BY-NC
The Ecology of Healthy Coasts
Our field research clearly showed that coastal instability resulting from sediment loss at the mouths of the dammed rivers was harming ecosystems along the shore. For example, we found that coastal regions downstream of free-flowing rivers had significantly more plant diversity. Many of these plants were found only in coastal areas, and therefore had high conservation value.
Coastal erosion due to lack of sediment input from the rivers also reduces critical nursery habitat, such as mangrove forest, where many commercially important fish species spend their juvenile stage. We found that fishing activity at the mouth of the free-flowing San Pedro River was much higher than around the mouth of the dammed Fuerte River. This loss of fishing potential comes at a cost of around $1.3 million every year.
Reduced sediment flow also deprives coastal estuaries of nutrients. Lucrative shrimp and oyster fisheries in the region we studied rely heavily on nutrient inputs from rivers. In the San Pedro River region, these fisheries generate around $5.8 million yearly; near the dammed rivers, they have been all but abandoned.
Coastal mangrove wetlands also protect shorelines from hurricanes and tropical storms, and serve as recreational areas and conservation habitat for wildlife. Knowing this, we calculated that the loss of these ecosystem services around the dammed rivers totals $3.9 million annually.
Vegetation profile of sandbars of the free-flowing San Pedro River (A) and dammed Santiago River (B), where receding black mangrove forest is being eroded away into the advancing coastline
Ezcurra et al., 2019, CC BY-NC
Still another valuable function that mangrove wetlands perform is storing "blue carbon" in plant tissue and soils, reducing the effects of climate change. But when coastlines recede and mangroves are destroyed, this carbon is released. We calculated that mangrove loss in our study region represented a loss of around $130,000 in annual carbon trading potential for this region.
Adding up all of the ecological services that coastal ecosystems provide, we estimate that the economic consequences of shoreline loss around the Santiago and Fuerte rivers related to hydroelectric damming totaled well over $10 million yearly.
Letting More Sediment Flow
Because sediments are so essential to areas around river mouths, reducing sediment trapping behind dams could mitigate some harmful impacts on coastal areas. There are several ways to do this — notably, sediment bypassing, or diverting a portion of the sediments flowing from upriver around dams and allowing it to rejoin the river downstream.
This strategy can be included in new construction or incorporated into existing dams. In addition to reducing dams' environmental impacts, it also increases dams' service lives by reducing the rate at which their reservoirs fill up with silt.
To date, environmental impact assessments of large inland dams have often failed to properly analyze the impacts that these dams will have downriver on coastlines, estuaries, deltas and lagoons. Our study shows how important it is to fully account for dams' environmental and economic impacts along coasts and basins.
Mexico may be at a juncture in its approach to hydropower. The Mexican government recently contracted with Hydro-Quebec, the world's largest hydroelectric power producer, to revamp existing dams across the country. And a recent study by a Mexican nongovernment organization, SuMar-Voces por la Naturaleza, reported that a long-disputed proposal to build a new hydroelectric dam at Las Cruces is neither financially feasible nor needed to meet energy demand for the region, prompting national groups to call for the final cancellation of the project.
We believe that Mexico and all nations working to develop efficient, low-impact energy sources should take a holistic approach to future dam-related projects, so they can weigh their potentially harmful consequences. The coastal effects that we documented should be part of those reviews.
Paula Ezcurra is a digital communications specialist with the Gulf of California Marine Program, University of California San Diego.
Octavio Aburto is an assistant professor of marine biology with the the Scripps Institute of Oceanography, University of California San Diego.
Disclosure statement: Octavio Aburto receives funding from the David and Lucile Packard Foundation, UC MEXUS and the Leona M. and Harry B. Helmsley Charitable Trust. Paula Ezcurra does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond her academic appointment.
Reposted with permission from our media associate The Conversation.
EcoWatch Daily Newsletter
By Arkilaus Kladit
My name is Arkilaus Kladit. I'm from the Knasaimos-Tehit tribe in South Sorong Regency, West Papua Province, Indonesia. For decades my tribe has been fighting to protect our forests from outsiders who want to log it or clear it for palm oil. For my people, the forest is our mother and our best friend. Everything we need to survive comes from the forest: food, medicines, building materials, and there are many sacred sites in the forest.
Map of the Knasaimos traditional lands.
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By Farah Aqel
Overthinkers are people who are buried in their own obsessive thoughts. Imagine being in a large maze where each turn leads into an even deeper and knottier tangle of catastrophic, distressing events — that is what it feels like to them when they think about the issues that confront them.
Ruminating<p>According to the late Susan Nolen-Hoeksema, a professor of psychology at Yale University, <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5796420/" target="_blank">ruminating</a> involves replaying a problem over and over in your mind. We ruminate by obsessing over our thoughts and thinking repetitively about various aspects of a past situation.</p><p>It usually involves regret, self-loathing and self-blaming. Rumination is associated with the development of depression, anxiety and eating disorders. </p><p>People prone to such patterns of thought may, for example, overanalyze every single detail of a relationship that breaks up. They often blame themselves for what has happened and are overcome with regret, with typical thoughts being: </p><p>- I should have been more patient and more supportive. </p><p>- I have lost the most perfect partner ever. </p><p>- No one will love me again.</p>
Worrying<p>Worrying is wanting to predict the future. It involves negative thoughts about things that might and might not happen.</p><p>- They'll not like me in the interview; they'll not give me the job. </p><p>- I haven't heard back from other employers. How long will I be unemployed?</p><p>These thoughts are energy-draining and distressing. They could happen to anyone under stress. But when you reach the point where your thoughts and worrying are preventing you from doing what you want to do — from living your life to the fullest — then you should take action.</p>
Catch Yourself Overthinking<p>Reuben Berger, a psychotherapist at the university hospital in the western German city of Bonn, recommends several practical steps that you could employ in your daily routine when you catch yourself worrying or ruminating.</p><p>One effective remedy, says Berger, is the <a href="https://www.uofmhealth.org/health-library/uf9938" target="_blank">thought-stopping technique.</a></p><p>"When the negative thoughts come or ruminations start, you say to yourself: 'Stop!,'" he says, adding that it is more effective when you actually say the word out loud.</p><p>He even recommends having a rubber band around your wrist to ping against yourself while saying the word. Adding a visual component by imagining a stop sign also makes the technique more powerful, he says.</p><p>The main idea here is conditioning yourself to stop the loop of worrying (making future predictions) or rumination (obsessing over past events).</p><p>Berger says the technique could take up to two weeks to take effect and that it needs to be practiced every day. "Consistency is very important," he says. </p>
Thoughts Are Just Thoughts<p>Another way of dealing with negative thoughts often used in modern therapy is realizing that thoughts aren't facts, says Berger.</p><p>He says it is important when we think something to ask: Is that real? Did that really happen? What is the worst thing that could happen?</p><p>Flight anxiety is one example where untrue thoughts are accepted as facts. Although air travel is the safest way to get around, people suffering from fear of flying accept their thoughts and fears as reality, then act upon them by refusing to fly.</p>
Mindfulness<p>Berger also recommends the use of mindfulness techniques, in which attention is paid to experiences in the moment without judging them, as a way of reducing worrying.</p><p>"Mindfulness helps you to distance yourself from your thoughts and to be more present in the moment," he says.</p><p><a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3432145/#R2" target="_blank">Several studies</a> have shown that mindfulness has a positive impact on reducing stress-related behaviors such as rumination and worrying, as focusing on the moment makes anxiety about other problems impossible.</p><p>Mindfulness can be practiced during routine activities by paying attention to your body and your surroundings. For instance, when you leave for work in the morning, you can focus on sensing the breeze, listen attentively to birds, feel the gravel under your feet and monitor your breath. </p>
Trick Your Brain Into Happiness<p>People plagued by obsessive thoughts do not always choose healthy ways like mindfulness to distract from them, however.</p><p> Dr. Edward Selby, a psychologist at Florida state university, has shown in a study that people try to avoid rumination by engaging in a range of uncontrolled behaviors, such as binge eating and substance abuse.</p><p>But he says that a much better way to overcome such distress is by distraction and shifting attention away from problems that are obsessing us.</p><p>There are many activities that can be used to distract from rumination, he says, and people should choose the one that works best for them. Here are some examples:</p><p>- Listen to music</p><p>- Read a book</p><p>- Take a hot shower</p><p>- Dance or exercise </p><p>- Talk to a friend (not about the problem)</p><p>- Watch a movie</p><p>- Mindfulness meditation</p>
Changing the Perception of Events<p>The way people perceive a situation largely influences their emotions and behavior. It is not the situation itself that determines how they feel, but rather the way they interpret it.</p><p>Reframing negative thoughts can lead to positive emotions and, subsequently, healthier behaviors — including a reduction in damaging overthinking and worrying.</p><p>Cognitive behavioral therapy (CBT) is currently a gold standard in psychotherapy. CBT aims to change the way people think and act. It largely involves challenging unhelpful beliefs or attitudes such as overgeneralization — thinking "I always fail at public speaking" when you have had one bad experience in front of an audience, for example — or "catastrophization," i.e., imagining the worst possible outcome to a situation. </p><p>A psychotherapist can teach people how to implement such thought-changing techniques into their lives. Techniques vary depending on their issues and goals.</p>
Solutions Are at Hand<p>Try to find ways of avoiding worrying, rumination and overthinking that make you feel most comfortable.</p><p>Incorporating any routine in your life when you're stressed isn't an easy task, but you can do it! If you feel overwhelmed, you can always seek professional help. </p><p><em>If you are suffering from serious emotional strain or suicidal thoughts, do not hesitate to seek professional help. You can find information on where to find such help, no matter where you live in the world, <a href="https://www.befrienders.org/" target="_blank">at this website.</a></em></p>
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By Michael Baker, Amanda Kvalsvig and Nick Wilson
On Sunday, New Zealand marked 100 days without community transmission of COVID-19.
Deaths From COVID-19 Per Million Population<img lazy-loadable="true" src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMzU0ODIyOS9vcmlnaW4ucG5nIiwiZXhwaXJlc19hdCI6MTY0MjkzMDc1OX0.7Yp1h1hokihlMJUurDukGmq-Y8NJB0V-07O1ukEjGt0/img.png?width=980" id="0fe6a" class="rm-shortcode" data-rm-shortcode-id="6bce85a610aee18e2f4f1c1caca7b8a0" data-rm-shortcode-name="rebelmouse-image" />
<div id="77fff" class="rm-shortcode" data-rm-shortcode-id="ce7b34f8986d3d36bee5d4d83ac0822c"><blockquote class="twitter-tweet twitter-custom-tweet" data-twitter-tweet-id="1292270210238447616" data-partner="rebelmouse"><div style="margin:1em 0">COVID-19 Update There are no new cases of COVID-19 to report in New Zealand today. It has been 100 days since t… https://t.co/Cz55ixGZUz</div> — Unite against COVID-19 (@Unite against COVID-19)<a href="https://twitter.com/covid19nz/statuses/1292270210238447616">1596936201.0</a></blockquote></div>
Getting Through the Pandemic<p>We have gained a much better understanding of COVID-19 over the past eight months. Without effective control measures, it is likely to continue to spread globally for many months to years, ultimately infecting billions and killing millions. The proportion of infected people who die appears to be <a href="https://www.medrxiv.org/content/10.1101/2020.05.03.20089854v4" target="_blank">slightly below 1%</a>.</p><p>This infection also causes serious <a href="https://www.bmj.com/content/370/bmj.m2815" target="_blank">long-term consequences</a> for some survivors. The largest uncertainties involve <a href="https://www.nature.com/articles/d41586-020-02278-5" target="_blank">immunity to this virus</a>, whether it can develop from exposure to infection or vaccines, and if it is long-lasting. The potential for treatment with antivirals and other therapeutics is also still uncertain.</p><p>This knowledge reinforces the huge benefits of sustaining elimination. We know that if New Zealand were to experience widespread COVID-19 transmission, the <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3310086/" target="_blank">impact on Māori and Pasifika populations</a> could be catastrophic.</p><p>We have previously described critical measures to get us through this period, including the use of fabric face masks, improving contact tracing with suitable digital tools, applying a science-based approach to border management, and the need for a dedicated national public health agency.</p><p>Maintaining elimination depends on adopting a highly strategic approach to risk management. This approach involves choosing an optimal mix of interventions and using resources in the most efficient way to keep the risk of COVID-19 outbreaks at a consistently low level. Several measures can contribute to this goal over the next few months, while also allowing incremental increases in international travel:</p><ul><li>resurgence planning for a border-control failure and outbreaks of various sizes, with state-of-the-art contact tracing and an upgraded alert level system</li><li>ensuring all New Zealanders own a <a href="https://www.nzma.org.nz/journal-articles/mass-masking-an-alternative-to-a-second-lockdown-in-aotearoa" target="_blank">re-useable fabric face mask</a> with their <a href="https://www.nzherald.co.nz/nz/news/article.cfm?c_id=1&objectid=12354409" target="_blank">use built into the alert level system</a></li><li>conducting exercises and simulations to test outbreak management procedures, possibly including "mass masking days" to engage the public in the response</li><li>carefully exploring processes to allow <a href="https://blogs.otago.ac.nz/pubhealthexpert/2020/06/16/preventing-outbreaks-of-covid-19-in-nz-associated-with-air-travel-from-australia-new-modelling-study-of-alternatives-to-quarantine/" target="_blank">quarantine-free travel</a> between jurisdictions free of COVID-19, notably various Pacific Islands, Tasmania and Taiwan (which may require digital tracking of arriving travellers for the first few weeks)</li><li>planning for carefully managed inbound travel by key long-term visitor groups such as tertiary students who would generally still need managed quarantine.</li></ul>
Building Back Better<p>New Zealand cannot change the reality of the global COVID-19 pandemic. But it can leverage possible benefits.</p><p>We should conduct an <a href="https://blogs.otago.ac.nz/pubhealthexpert/2020/06/11/five-key-reasons-why-nz-should-have-an-official-inquiry-into-the-response-to-the-covid-19-pandemic/" target="_blank">official inquiry into the COVID-19 response</a> so we learn everything we possibly can to improve our response capacity for future events.</p><p>We also need to establish a specialized national public health agency to <a href="https://blogs.otago.ac.nz/pubhealthexpert/2017/12/20/the-havelock-north-drinking-water-inquiry-a-wake-up-call-to-rebuild-public-health-in-new-zealand/" target="_blank">manage serious threats to public health</a> and provide critical mass to <a href="https://blogs.otago.ac.nz/pubhealthexpert/2020/02/05/a-preventable-measles-epidemic-lessons-for-reforming-public-health-in-nz/" target="_blank">advance public health generally</a>. Such an agency appears to have been a key factor in the success of Taiwan, which avoided a costly lockdown entirely.</p><p>Business as usual should not be an option for the recovery phase. A recent <a href="https://www.nzherald.co.nz/business/news/article.cfm?c_id=3&objectid=12353555" target="_blank">Massey University survey</a> suggests seven out of ten New Zealanders support a green recovery approach.</p><p>New Zealand's elimination of COVID-19 has drawn attention worldwide, with a description just <a href="https://www.nejm.org/doi/full/10.1056/NEJMc2025203" target="_blank">published</a> in the New England Journal of Medicine. We support a rejuvenated World Health Organization that can provide improved global leadership for pandemic prevention and control, including greater use of an elimination approach to combat COVID-19.</p>
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