Graduation year: 2022
Semester/year area of interest proposed: Spring 2020
Major status: ENVS single major
Other major (if applicable):
Minor(s) (if applicable):
Ever since humans began to settle into larger, denser populations, we have been implementing infrastructure projects in an attempt to control the surface-based hydrologic system and ensure society has a constant and abundant supply of fresh water. These projects have been implemented on a variety of scales, from giant dams hundreds of meters high capable of holding back multiple years’ supplies of water to small irrigation channels supporting a single farm. For the vast majority of this history, the outcome of the effort has been focused on meeting the anthropogenic needs of agriculture and municipalities. River basin impact increases with economic activity (Nilsson et al. 2005), and this economic growth driven mindset has led to certain impacts on ecological processes, geologic processes, and human well-being caused by the construction of dams, stream channel modification, and land use changes.
Although all three of these causes play a role in impacting river systems, large scale river systems are mainly impacted by the construction of dams, and environmental flows are usually implemented by regulating water released from dams. In the United States, all watersheds larger than 2000 square kilometers, about half the size of Rhode Island, have some dams (Graf 1999). In addition, just 3% of dams in the US account for 63% of the country’s total storage (Graf 1999). Although the dam building era is essentially over in the United States (Graf 1999), large-scale development of the surface-based hydrologic system in other parts of the world continues. There are over 45,000 dams worldwide that are together capable of holding back over 15% of the total annual global river runoff (Nilsson et al. 2005), and less than 35% of the world’s large river systems (LRS) remain unmodified by humans.
The ecological and geologic impacts of this fragmentation and flow regulation due to dams are numerous. The eight LRSs that span seven or more biomes are all strongly or moderately affected (Nilsson et al. 2005). The fragmentation of rivers has a huge impact on the ability of fish to migrate upstream and downstream. In their undammed state, rivers generally undergo large fluctuations in discharge, temperature, and sediment supply depending on the season. However, downstream from dams, these factors stay relatively consistent, and often even experience an inversion of the natural regime as water is released downstream for agricultural purposes during the drier season (Arthington 2012). River reaches below hydroelectric dams can experience an extremely sporadic flow regime that varies daily as the need for electricity fluctuates. Together, these highly unnatural alterations, or lack thereof, have negative impacts on the ecology of the river that is so used to the natural variance (Arthington 2012).
The concept of environmental flows began as a way to sustain ecological processes on top of providing water for anthropogenic use. They were thought to be implemented as a baseflow requirement, meaning the discharge of the river cannot fall below a certain amount (Acreman et al.). More recently, however, it has been recognized that environmental flows ought to follow this unimpacted flow regime of high flows and low flows in order to successfully sustain its ecosystem (Acreman et al. 2014). In addition to sustaining ecological and geologic processes through environmental flows, there has been a recent surge in the concept of environmental flows providing ecosystem services to support human well-being (Anderson et al. 2019). A significant new element of the 2018 Brisbane Declaration and Global Action Agenda on Environmental Flows is the emphasis on including people in the environmental flow discussion (Anderson et al. 2019). Therefore, the contemporary definition of environmental flows takes this into account.
The social and cultural needs of riparian communities vary dramatically. Historically, the most common “need” other than water and electricity supply that was taken into account when developing rivers was preserving their natural beauty and characteristics for people to enjoy and recreate (Anderson et al. 2019). More recently, environmental flows have taken into account less visible relationships between people and rivers (Anderson et al. 2019). The use of rivers for transportation is another factor that should be taken into account with environmental flows (Anderson et al. 2019); the water level of a river needs to be at a certain height for it to be navigable. Rivers as being sacred is a concept that is also increasingly being recognized as an important aspect of environmental flows. Religious groups develop “customs, rituals, and philosophies that reflect and align with the natural rhythms of the river” (Anderson et al. 2019, 11). A key component of thinking of rivers as social and cultural also involves respecting the rights and needs of indigenous groups through the lense of all of these concepts, who have been benefiting from what rivers provide long before experiencing these more modern modifications.
Although controversial, another way to attempt to restore a river to its natural state is through dam removal. The long term effects of dam removal include a large increase in biodiversity as the riparian ecosystem is allowed to restore its natural processes (Bednarek 2001). These effects take place on a larger scale and longer time frame than any environmental flow ever would, but conversely limit the possibility for anthropogenic use. An identifiable short term impact on the riparian ecosystem is an increase in sediment supply that may cause suffocation and abrasion, but previously observed dam removals have shown that this occurs over a very short time frame following the removal (Bednarek 2001).
Designing environmental flows to accommodate these varying needs can come in different forms depending on the intended outcome of the flow. Acreman et al. (2014) outline two different types: the natural flow regime paradigm and the designer paradigm. The former attempts to maintain a flow regime as close as possible to the natural flow regime in order to maximize the conservation of ecological species and systems (Acreman et al. 2014). The latter attempts to design a flow regime to “achieve specific ecological and ecosystem service outcomes”, and is more realistic for heavily modified river systems (Acreman et al. 2014).
- What are the key processes that alter natural flow regimes at different scales?
- Why do humans engage in altering the natural flow regime of rivers?
- Who stands to benefit from the implementation of environmental flows?
- How can environmental flows be implemented in order to balance the needs of both humans and riparian ecosystems?
- GEOL 150 – Environmental Geology – fall 2020 – This course relates geologic processes with human activity and includes consequences of dams and channel modification.
- GEOL 280 – The Fundamentals of Hydrology – fall 2019 – This course goes into detail on the science of fresh water and provides information on hydrologic processes.
- GEOL 340 – Spatial Problems in Earth System Science (GIS) – spring 2019 – This course also relates major earth systems with people and is focused on developing analytical skills, primarily spatially.
- ENVS 460 – Topics in Environmental Law and Policy – fall 2021 – This course is highly applicable to environmental flows, as it includes water policy which can be connected to environmental flow policy.
Here are the required breadth courses I will include in my ENVS major/minor: CHEM 110, GEOL 170, ECON 260, SOAN 265, HIST 239, PHIL 215. These are in addition to my ENVS core courses, and the area of interest courses I propose above.
Revisions to date
17 March 2020 feedback from Liz Safran
- Describe more of a range of scale instead of just jumping right into large river systems.
- Acreman, Mike, Angela H Arthington, Matthew J Colloff, Carol Couch, Neville D Crossman, Fiona Dyer, Ian Overton, Carmel A Pollino, Michael J Stewardson, and William Young. 2014. “Environmental Flows for Natural, Hybrid, and Novel Riverine Ecosystems in a Changing World.” Frontiers in Ecology and the Environment 12 (8): 466–73. https://doi.org/10.1890/130134.
- Anderson, Elizabeth P., Sue Jackson, Rebecca E. Tharme, Michael Douglas, Joseph E. Flotemersch, Margreet Zwarteveen, Chicu Lokgariwar, et al. 2019. “Understanding Rivers and Their Social Relations: A Critical Step to Advance Environmental Water Management.” WIREs Water 6 (6): e1381. https://doi.org/10.1002/wat2.1381.
- Arthington, Angela H. 2012. Environmental flows: Saving rivers in the third millennium. Berkeley: Univ. of California Press. https://doi.org/10.1525/california/9780520273696.001.0001.
- Bednarek, Angela T. 2001. “Undamming Rivers: A Review of the Ecological Impacts of Dam Removal.” Environmental Management 27 (6): 803-14. https://doi.org/10.1007/s002670010189.
- Graf, William L. 1999. “Dam Nation: A Geographic Census of American Dams and Their Large-Scale Hydrologic Impacts.” Water Resources Research 35 (4): 1305–11. https://doi.org/10.1029/1999WR900016.
- Nilsson, Christer, Catherine A. Reidy, Mats Dynesius, and Carmen Revenga. 2005. “Fragmentation and Flow Regulation of the World’s Large River Systems.” Science 308 (5720): 405–8. https://doi.org/10.1126/science.1107887.