The Human Environment. One major source for debates on environmental issues is the assumption many humans hold that we are separate from the environment, that we stand apart. As a human, I certainly hold a bias that we are unique amongst the species that form the biosphere, however, we are not apart or separated from the environment. I will let religious leaders and philosophers debate our spirits, souls, and Mind, instead I will focus on our physical form. Our bodies are part of the environment, the environment forms us from the nutrients necessary for all of our biochemical pathways to the world around us. The other facet of this fact is that we are part of the environment by being part of the biological community that shapes this world. As such, what we do within this environment is natural, is a natural outgrowth of who we are as a species. You cannot separate a beaver from how it forms dams or the environment the beaver creates by forming dams. As human population grows, our very numbers will shape the biosphere for the foreseeable future.
Opining away. So, humans are natural beings, or at least our physical form is, thus we are part of nature, part of the environment. But we also are smart, we may have the highest cognition and level of self-awareness, sapience of any species on Earth. We should know that our interconnectedness within the environment means that what we build, how we treat, and our actions within the environment not only affect the other components of the environment but affect us as well. We should know better than to destroy that which sustains and supports us. Take species loss as an example. As Thomas Lovejoy said, and here I paraphrase: We are not the first species to drive another species extinct, we are not the first species to drive many other species extinct, but we are the first species who knows we are doing this and who know very well to stop.
Damming. The Tethysphere has been altered by the wondrous and amazing works of human ingenuity (and beaver ingenuity too). We have dammed nearly every major river in the northern hemisphere and are ambitious enough to plan the damming of major rivers in the southern hemisphere. Humans have dammed streams for millennia, creating farm ponds as a way to store water for agriculture in semi-arid lands. In North America we have built massive structures to reshape the natural course of rivers. Given the context of my argument above then these massive alterations of rivers are natural since humans are natural beings contextualized within their environments. However, our actions have unintended consequences. We learn more each day about how dams change the rhythm of flow, alter the course of nutrient-bearing sediments, and rearrange the discharge of energy and how these changes may increase the risk and severity of flooding. Now that we know, a movement is afoot to remove dams and restore natural flows. But, and yet, new dams are constructed every day. We should know better.
The Channel Conundrum. Humans are drawn to farm in the alluvial flood plain, the near-river habitat that has received nutrient rich sediments from floods over long periods of time. This is a great place to farm, but, yes, rivers still flood, and farms are wiped out, and we grieve and plan and create a solution. We channelize the rivers, straighten them and form dykes to hold the water in. The intended consequence is farming relatively safe from flooding. Dykes protect municipalities from flooding too, because we have built close to the water again and again. The unintended consequences include loss of habitat for fisheries. More to the point, channelization creates a sluice way for massive amounts of energy to rush downstream and expand as floodwaters below the dykes. The energy from the water carves out the substrate, changing the way the rivers process energy and wastes. In combination with dams, channelization reduces the amount of nutrient-rich sediments that previously spread into the flood plain, so the farm land becomes nutrient poor and more fertilizers are needed to sustain crops, the overflow of which enter the rivers-a cycle of pollution. We now know that these unintended consequences increase nutrient toxicity in rivers and fisheries, in drinking water for humans and domesticated animals, and for wildlife. Perhaps we could work to create better farming practices while removing dykes and allowing rivers to reclaim their meandering ways. Since humans are part of the environment, we could science the heck of this and create solutions that sustain farming, rivers, and species diversity.
Hydroelectricity, Climate Change Solution or Curse Word. Using water released from dams to turn turbines to create electricity. Brilliant! Or is it? Do the unintended consequences of dams outweigh the good of energy production with relatively low carbon emissions? Oh, I don’t know. Certainly, it would be bad form to build new hydroelectric dams. In-stream turbines may be the answer, but they will still disrupt flow, impairing the environment and leading to population loss and the resulting species extirpations. With the milestone of 8 billion humans on the planet rapidly approaching we will have no choice but to enact a triage approach in our solution building. Does the ballooning and early arrival of the more harrowing impacts of climate change trump all other issues? Countries facing crises of water availability and who want to create their own energy will build more and larger hydroelectric dams in the decades to come. When I first worked in Mongolia, we were fortunate to survey biodiversity in rivers with no impoundments or dams, but that is changing as climate change drives widespread drought in Central Asia. Is river biodiversity worth sacrificing to get off coal and other non-renewable energies in the face of catastrophic effects of climate change? More questions than answers here, but one fact is clear, as humans we are part of the environment and we need to solve these issues, we need to address downstream consequences of our actions, and we need to do so now as we cannot escape the environment we help shape, for it is all around us and it is part of us.
For more information:
Gregory, K.J., 2006. The human role in changing river channels. Geomorphology, 79(3-4), pp.172-191.
Ngor, P.B., Legendre, P., Oberdorff, T. and Lek, S., 2018. Flow alterations by dams shaped fish assemblage dynamics in the complex Mekong-3S river system. Ecological Indicators, 88, pp.103-114.
Pringle, C.M., Freeman, M.C. and Freeman, B.J., 2000. Regional effects of hydrologic alterations on riverine macrobiota in the new world: tropical-temperate comparisons: the massive scope of large dams and other hydrologic modifications in the temperate New World has resulted in distinct regional trends of biotic impoverishment. While neotropical rivers have fewer dams and limited data upon which to make regional generalizations, they are ecologically vulnerable to increasing hydropower development and biotic patterns are emerging. AIBS Bulletin, 50(9), pp.807-823.
Wang, Y., Rhoads, B.L. and Wang, D., 2016. Assessment of the flow regime alterations in the middle reach of the Yangtze River associated with dam construction: potential ecological implications. Hydrological processes, 30(21), pp.3949-3966.