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Riparian Wetland
Management Plan

11/23/2020

Conservation Action Plan for Management

of Riparian Wetlands in the American West

 

I Introduction and Background

            Riparian wetlands are distinct corridors following alluvial and headwater streams that contain well-adapted, diverse flora and fauna. Riparian corridors are the most diverse, complex, and dynamic ecosystems in the world (Naiman 1993). They are present throughout all terrestrial ecosystems with inland water and are sometimes known as “floodplains”. For millennia, humans have used these unique ecosystems for a myriad of resources and services. Many ancient civilizations were significantly influenced by the presence of flowing water, providing fertile land in otherwise inhospitable regions. The fertile crescent in Mesopotamia or the Nile in Egypt are just two examples of how instrumental these ecosystems can be for the progress in technology and society that humans have conducted within recorded history. We associate towns and trade with rivers for good reason, as they are the most succinct and inexpensive way to transport goods and provide clean drinking water to a populace. The Riparian Wetlands surrounding these waterways have traditionally been highly misunderstood and unstudied, as they appear more as a transitionary edge than as a distinct ecosystem to the untrained eye. This lack of knowledge has detrimentally affected the perceived importance of riparian corridors.

            Despite only composing 0.8% to 2.0% of terrestrial landscapes, these crucial ecosystems complete an inordinate and disproportionate number of ecosystem services. These services include water purification, temperature regulation, water retention, erosion control, mitigation of flooding, nutrient cycling, carbon sequestration, cultural/recreational use, wildlife habitat, promotion of fish populations, macro/micro-climate moderation, and sediment transport (Talukdar 2020; Theobald 2010). They also detoxify waterways of heavy elements, like Selenium (Neupane 2020). The varied biogeochemical processes that occur in these corridors benefit wetland and upland species alike, ensuring diverse, adequate nutrition for whole watersheds (Naiman 1993).

            These varied services and benefits are at great risk because riparian wetlands are the most susceptible ecosystems to anthropogenic activity and development (Allan 2004). In the last 200 years, an estimated eighty to ninety percent of riparian corridors have disappeared or are functionally extinct in North America (Naiman 1993; Schneider 2017). Until the 1970s, the drainage of wetlands and maintenance of buffer zones were either unregulated or controlled by civil engineers. Scientists have been rushing to determine the effects that these changes caused throughout a variety of regions and how to prevent further degradation of these corridors.

            In recent scholarship, the conservation and restoration of riparian wetlands has become the frontline in the effort to conserve natural hydrology and water resources. This is due to an increase in both human population and land development, causing water consumption to progressively increase in a number of ways. Though this has a disastrous effect on all terrestrial ecosystems, the humanitarian and ecological concerns are especially great in arid regions where riparian wetlands represent the primary functional wetlands in their environment (Macfarlane 2017).

            In America, the Southwestern region is generally arid, has been urbanized significantly, and has channelized most of its large alluvial waterways. This makes the region’s riparian wetlands especially susceptible to further degradation. This degradation is being caused by a multiplicity of factors due to the riparian wetlands’ delicate, liminal position. The list of threats is extensive, so I will be describing them in three categories: abiotic change, biotic change, and climate change. 

 

II Threats: Abiotic Change 

    

            This change is the most pervasive and far-reaching. Humans have significantly affected a number of abiotic and geomorphic conditions in riparian corridors via development, conventional streambank stabilization techniques, dams, water use, and agriculture. Before the 1970s, development on wetlands was unregulated, so a lot of existing infrastructure and privately owned structures lie on areas with historically relevant riparian corridors. At this point, these areas have been so utterly changed that we will be disregarding them as potential areas of restoration or conservation. Instead, we will be focusing on the other abiotic changes that are limiting connectivity and increasing flow modification overall.

            Dams are large, wall-like structures that block the flow of a river, forming large reservoirs that have traditionally provided humans with excess water in one locale. This approach has been questioned in recent years as our understanding of river hydrology and dynamics has increased. Debatably, dams have the greatest anthropogenic effect on environment (Schneider 2017). Dams cause hydrological poverty and widespread ecological stress throughout a watershed by concentrating water in one location. They decrease hydroperiod, water depth, and deteriorate wetlands downstream (Talukdar 2020). They disrupt natural flow regimes, limit variation in flow, and reduce flood pulses (Schneider 2017).

            Dams may be strikingly potent reminders of human development, but the subtle channelization techniques used throughout America’s waterways may be even more disastrous to riparian wetland health. Channelization is a process by which a river’s banks become hardened by humans stabilizing streambanks with a non-permeable substance. It is critical to understand that channelization and streambank stabilization are natural processes as well as human techniques. Thus, the threat to riparian wetlands comes from the methodology used to complete these processes, not the processes themselves (Bigham 2020). Civil engineers have traditionally used “hard” techniques that incorporate large rocks, concrete structures, recycled construction materials, and minimal vegetation. They preferred techniques that yielded static riverbanks and limited flood disturbance regimes.

            Even today, literature on hard techniques and use of riprap [1] is increasing whilst integrative techniques involving revegetation remain relatively underutilized (Bigham 2020). Hard techniques that incorporate riprap are known to be the least effective in restoration and yield low quality streams and riparian corridors (Janssen 2019). Furthermore, the regulation of flow via any of these techniques causes faster flows and decreases the duration of low flows. Riparian corridors require active disturbance regimes that vacillate from low flows to seasonal flooding across spatial and temporal periods in order to maintain functional hydrologic regimes (Naiman 1993). Flow regulation maintains a steady-state equilibrium that limits this vacillation of flow and degrades riparian corridors.

 

III Threats: Biotic Change

            Hydrological shifts and land-use changes [2] significantly impacts the kind of plant community that arises in a riparian wetland (Mendez-Toribio 2014). The most demonstrable of these changes in plant community is the encroachment of upland species into riparian corridors. Flow regulation strips water from surrounding wetlands, altering the hydroperiod; thus, obligate and facultative plants[3] perish, leaving upland plants a newly dry space to enter. This terrestrialization is prevalent in alluvial waterways while smaller headwater streams tend to maintain their hydroperiod and plant community (Macfarlane 2017). Typically found in natural areas, these smaller streams tend to require smaller buffer zones and generally have more individual plants than localities with urban or agricultural use at the forefront (Mendez-Toribio 2014).

            Another threat to vegetation in riparian corridors is the presence of cattle (Theobald 2010). Cattle ranches are prevalent across the American West and represent a major section of land use and stakeholders. Their livestock trample banks when looking for water and consume water resources themselves. Their trampling behavior fragments plant communities and can disrupt restoration efforts due to the lack of oversight concerning the movement and prevalence of livestock (Talukdar 2020).

            Finally, invasive species are present in many riparian corridors, competing with the native plant community. Native Cottonwood trees are dying, opening space for invasive trees like the Salt Cedar (Theobald 2010). Fortunately, this appears to be a relatively minor threat. Once the abiotic features of the environment are restored, wetland ecologists suggest that the vegetative community will have an easier time revegetating their habitat more fully (Bariteau 2013). The disturbance regimes unique to riparian wetlands lessen interspecies and intraspecies competition, yielding a more even playing field than some other environments (Bejarano 2020).

 

 

IV Threats: Climate Change

            We currently know very little concerning the effect that climate change has on arid riparian corridors. Current predictions suggest that most of the American West will be experiencing an increase in temperature and a decrease in precipitation (Theobald 2010). However, these models are never exact; climate change may alter flow regimes in unprecedented ways due to alterations in precipitation and extreme weather events (Schneider 2017). Our predictive models would indicate that disturbance regimes in arid alluvial systems would decrease due to less precipitation and thus less flooding [4]. A lack of a regular disturbance regime is already negatively affecting riparian corridors, making this a serious threat that we cannot address in anyway other than strengthening their current extent and habitat quality.

 

V Management Plan

Decision One: Acquire Protected Buffer Zones

            Before any restoration work can begin on riparian corridors, we must first acquire the corridors themselves. Due to the importance of these ecosystems and the looming humanitarian crisis arising from their degradation, we would first contact lobbyists and responsible governmental bodies and agencies. ~48% of all riparian corridors are owned by governmental agencies, ensuring that with a collaborative approach to their conservation, at least half could be secured (Theobald 2010). We would create a 501(c4) charity to pay these lobbyists, contact a series of large conservation bodies (WWF, Sierra Club, etc.) to help pay for buffer zones, and send letters to representatives within state and federal legislatures. I predict that this extensive approach would ensure that a non-zero number of riparian buffer zones would be created surrounding waterways of the American West.

            The other half of potential buffer zones are split primarily between various Native American Tribes and private landowners. I am not concerned about the Native American peoples’ ability to conserve and restore their own riparian corridors, and thus I would inform them of the project and leave them to their own devices. I would communicate this document and relevant scientific literature so that a channel of understanding may be developed between our communities. Regular correspondence would be maintained to ensure this beneficial approach.

            Private landowners represent a much larger concern. In the Pacific Northwest, which has similar demographics of private landowners, attempts to increase the size of buffer zones have traditionally been met with staunch resistance (Chapman 2020). Science was used as an obfuscation for a values-laden debate that led to no significant problem-solving. In fact, a study of this particular debate indicated that the management plan was relatively unimportant within the debate, suggesting that a management plan is necessarily preliminary (Chapman 2020). Due to the relative abundance of private landowners who own riparian buffer zones, a “foot-in-the-door” approach may be considered that limits the size of the buffer zone. This is a fallback option that would increase edge effects and decrease functional habitat size (Mendez-Toribio 2014). Despite these negative effects, it is crucial that the program builds community with private landowners, so finding compromise is paramount.

            With government support, some proportion of land could be acquired via eminent domain, but this seems unlikely to occur. I would prefer to communicate with landowners directly, explaining the importance of riparian buffer zones and offering access to a subsidy that would pay landowners if they completed two actions: prevention of cattle from entering riparian buffer zones and prevention of development upon the defined corridor. I predict that this subsidy would yield a non-zero number of landowners that would join our cause and cede riparian buffer zones to be conserved and ecologically restored under the program.

            Another body of stakeholders that will likely not be in support of the program are cattle ranchers. Ranchers require a water source for their cattle and our program will be preventing cattle from entering the conserved land. With the support of government agencies, wells will be established for cattle ranchers to alleviate their cattle’s over-reliance on their local waterways. We will educate cattle ranchers about the importance of their riparian corridors and how proud they should be for deciding to conserve them. Propaganda [5] will be circulated within their community to allow an empathic response to this confusing topic.

            Preferably, a 100 meter buffer zone would extend in both lateral directions from the largest of alluvial waterways once acquired. This buffer size would vary depending on stream size, as smaller streams require less of a buffer zone and the largest corridors require whole flood plains as buffers (Naiman 1993). Not enough studies have been completed for me to suggest a particular numerical relationship between size of the waterway and the buffer zone, but we do understand them as positively correlated.

            Necessarily, each land deal will look different and require a different size of buffer zone. The goal is not to maintain a 100-meter buffer zone on all waterways, but rather to build confidence and community within these arid states. I predict that this foot-in-the-door approach will allow for restoration to begin swiftly, while limiting negative community response from interested stakeholders. I expect that a majority of waterways will have buffer zones appropriate to their size by the year 2030. This program would continue beyond 2030, leading to a slow growth and expansion of riparian buffer zones. 

 

Decision Two: Soil Bioengineering

            Once a sufficient number of riparian buffer zones are established as protected sites, we can begin to restore a functional abiotic environment. Soil bioengineering is an integrative approach to streambank stabilization that includes both hard techniques and use of native vegetation. Firstly, riprap and large concrete structures would have to be demolished before work could begin on integrative approaches. Stakeholders may be worried about the destruction of long-standing conventional river stabilization structures, though it has been demonstrated that the age of streambank stabilization structures has no effect on the quality of habitat formed nor their ability to protect against floods (Janssen 2019).

            Small dams will also be demolished, though taller dams will be maintained. Small dam removal has been studied more than tall dam removal. Tall dam removal has also increased terrestrialization of surrounding areas. Furthermore, downstream effects to dam removal remain unstudied (Ravot 2020). Preliminary reports suggest that the vegetative species richness doesn’t decline within eight years of any dam removal (Lisius 2018). In fact, dam removal has been shown to increase vegetative growth overall (Orr 2006). Invasive species must be managed efficiently after a dam removal due to this effect. There is also a societal perception that land where a reservoir used to be will stay as a mudflat forever unless developed. This means that previous reservoirs must be conserved immediately, and landowners must be educated on Gleasonian succession (Orr 2006).    

            An integrative approach will begin with the introduction of glaciofluvial rock to the bottom of larger waterways. This technique stabilizes streambanks without channelization, makes large-scale geotextiles unnecessary, is relatively inexpensive, and degrades the steepest bank slopes (Bariteau 2013). I predict that this heterogenous mixture of rock will increase structural heterogeneity within the stream, increase functional habitat, and increase functional plant diversity (Bolpagni 2020). Some other techniques may be incorporated, such as small-scale geotextiles set beneath banks to allow significant plant growth above (Yan 2020). This would act as an alternate technique due to the presence of landowners and urban planners most concerned about their land being flooded by disturbance regimes (Tisserent 2020).

            Following these hard techniques, the revegetation process will begin at a large, diverse scale. I can only give generalized suggestions concerning what species of plants should be planted due to no information on how flow regime affects plant community and the extreme variance across even one state, let alone multiple (Bejarano 2020; Macfarlane 2017). We do know that woody vegetation yields debris, chemical nourishment, routes sediment, and can regulate light and temperature (Naiman 1993). Woody species are also more resilient to hydrological changes (Bejarano 2020). Unexpectedly, herbaceous plants have an inordinate role in establishment of banks after disturbances (Ravot 2020). Ergo, I suggest a two-pronged approach to revegetation. Herbaceous native plants for each locality will be determined and planted in tandem with a crib wall of shrubs and trees. Invasive species will be managed until 2040 alongside these plantings. The presence of this vegetation will provide tensile strength to streambanks via root networks, increase drainage of streambanks, and create micro-habitats for other plants and animals (Bigham 2020; Janssen 2019). I predict that this approach will revegetate greater than 50% of riparian corridors with native plants [6] by 2040. I also predict that a positive feedback loop will be initiated in which the revegetation and crib walls of woody species promote the auto-reintroduction of surrounding native plants and animals (Tisserent 2020). Finally, I will consider this part of the plan a success if greater than 50% of alluvial waterways experience a sedimentation change towards historic conditions. This will be evaluated via GIS and satellite imaging every year for at least 20 years.

 

Decision Three: Decreasing Human Population Size in the American West

            The Colorado River has been reduced to less than 1% of its historic flow (Schneider 2017). This lack of flow can be attributed to an over-consumption of water by human activity at the current moment. The capacity to act in the benefit of riparian wetlands and the future of humanity is limited by this current use (Schneider 2017). Our only option to prevent a humanitarian crisis is to promote the active emigration from arid states and especially urban centers within these states. Water consumption, urbanization, and agriculture have the greatest effect on the health of riparian corridors, which are directly linked to the health of future humans (Macfarlane 2017). I propose three nested subsidies to address the water consumption issues in the American West and to prevent a looming public health crisis.

 

 

Subsidy I: Incentive for Individuals and Families

           to Emigrate from Arid States

           

        This subsidy will promote the motion of humans out of the following regions: Southwestern Colorado, Nevada, Arizona, Utah, New Mexico, Western Texas, and Southern California by offering a $15,000 incentive to emigrate. I predict that by 2040, the human population across these states will not have grown in number.

Subsidy II: Incentive for Individuals to Work in the

            Field of Ecological Restoration      

        This subsidy will promote the formation of jobs and create a dedicated workforce to help restore riparian corridors. I will be using the precedent of the New Deal (especially its formation of the CCC) as a blueprint to implement this subsidy.

Subsidy III: Incentive for Individuals and Families

             to Emigrate from Arid Cities

         Urbanization and the growing population of cities is the greatest threat to riparian corridors. Thus, people in the cities must emigrate, if we are to continue living in the American West. Water is being consumed at a high rate in cities and is being diverted from agricultural needs (Theobald 2010). Over 10 years, a $20,000 incentive would be available for emigration out of arid cities within the defined region. This incentive would decrease by $5,000, every five years after 2030. Those in poverty and the homeless would be offered jobs under the decree of subsidy II. I predict that this would form a functional workforce swiftly and allow for proper ecological restoration in a timely manner.

            I must be clear here and state that I am not asking people to leave cities or these states; however, I am promoting their emigration. This would not leave ghost towns or abandoned states, but rather slightly less populous cities, more sustainable water consumption, and a greater quality of life for all involved. I predict that these subsidies would decrease overall water consumption, return water flow of major alluvial waterways to greater than 20% of monthly discharge, and create numerous jobs in the growing field of ecological restoration.

 

VI Conclusion

            The issue of riparian wetlands in arid states cannot be understated. We cannot wait any longer to do something about these dwindling water resources, disappearing ecosystem services, and destroyed habitats. Within fifty years, arid states may be inhospitable to humans if water consumption continues to increase, leading to further desertification. Cities are slowing running out of groundwater and surface water; they will become deserted if waterways are not restored. The circumstances are dire and call for immediate action.    

 

Works Cited

 

Allan JD. 2004. Landscapes and riverscapes: The influence of land use on stream ecosystems. Annual Review of Ecology, Evolution, and Systematics 35: 257-284).

Bariteau L, Bouchard D, Gagnon G, Levasseur M, Lapointe S, Berube M. 2013. A riverbank erosion control method with environmental value. Ecological Engineering 58: 384-392.

Bejarano MD, Sarneel J, Su X, Sordo-Ward A. 2020. Shifts in Riparian Plant Life Forms Following Flow Regulation. Forests 518: DOI 10.3390/f11050518.

Bigham KA. 2020. Streambank stabilization design, research, and monitoring: The current state and future needs. American Society of Agricultural and Biological Engineers. 63 (2): 351-387.

Bolpagni R. 2020. Linking vegetation patterns, wetlands conservation, and ecosystem services provision: From publication to application. Aquatic Conservation: Marine and Freshwater Systems. 30 (9): 1734-1740.

Chapman M, Satterfield T, Chan KMA. 2020. How value conflicts infected the science of riparian restoration for endangered salmon habitat in America's Pacific Northwest: Lessons for the application of conservation science to policy. Biological Conservation 244. 10.1016/J.BIOCON.2020.108508

Janssen P, Cavaille P, Bray F, Evette A. 2019. Soil bioengineering techniques enhance riparian habitat quality and multi-taxonomic diversity in the foothills of the Alps and Jura Mountains. Ecological Engineering. 133: 1-9. 

Lisius GL, Snyder NP, Collins MJ. 2018. Vegetation community response to hydrologic and geomorphic changes following dam removal. River Research and Applications. 34 (4): 317-327. 

Macfarlane WW, Gilbert JT, Jensen ML, Gilbert JD, Hough-Snee N, McHugh PA, Wheaton JM, Bennett SN. 2017. Riparian vegetation as an indicator of riparian condition: Detecting departures from historic condition across the North American West. Journal of Environmental Management 202 (2): 447-460.

Mendez-Toribio M, Zermeno-Hernandez I, Ibarra-Manriquez. 2014. Effect of land use on the structure and diversity of riparian vegetation in the Duero river watershed in Michoacán, Mexico. Plant Ecology 215 (3): 285-296.

Naiman RJ, Decamps H, Pollock M. 1993. The Role of Riparian Corridors in Maintaining Regional Biodiversity. Ecological Applications 3 (2): 209-212. 

Neupane P, Bailey RT, Tavakoli-Kivi S. 2020. Assessing controls on selenium fate and transport in watersheds using the SWAT model. Science of the Total Environment 738: 140318.

Orr CH, Stanley EH. 2006. Vegetation development and restoration potential of drained  reservoirs following dam removal in Wisconsin. River Research and Applications 22 (3): 281-295.

Ravot C, Laslier M, Hubert-Moy L, Dufour S, et al. 2020. Large dam removal and early spontaneous riparian vegetation recruitment on alluvium in a former reservoir: Lessons learned from the pre‐removal phase of the Sélune River project (France). River Research and Applications 36: 894-906.

Schneider C, Florke M, De Stefano L, Petersen-Perlman JD. 2017. Hydrological threats to 

riparian wetlands of international importance - a global quantitative and qualitative 

analysis. Hydrology and Earth System Sciences 21: 2799-2815.

Talukdar S, Pal S, Chakraborty A, Mahato S. 2020. Damming effects on trophic and habitat state of riparian wetlands and their spatial relationship. Ecological Indicators 118. 

Theobald DM, Merritt DM, Norman III JB. 2010. Assessment of Threats to Riparian Ecosystems in the Western U.S. Prepared for Western Environmental Threats Assessment Center, Prineville. Accessible at: https://www.fs.fed.us/biology/nsaec/assets/theobaldassmntofwstrnriparianthreats20101.pdf 

Tisserent M, Janssen P, Evette A, Gonzalez E, et al. 2020. Diversity and succession of riparian plant communities along riverbanks bioengineered for erosion control: a case study in the foothills of the Alps and the Jura Mountains. Ecological Engineering 152.10.1016/J.ECOLENG.2020.105880 

Yan H, Pengcheng W, Hao S, Difang W, et al. 2020. Sustainability of riparian zones for non-point source pollution control in Chongming Island: Status, challenges, and perspectives. Journal of Cleaner Production 244. 10.1016/J.JCLEPRO.2019.118804

 

Footnotes:

[1] Riprap are large rocks placed on the slope of a riverbank for stabilization.

[2] Surrounding riparian wetlands.

[3] Wetland-type plants.

[4] In the American West.

[5] I use the term propaganda in its most neutral sense: a piece of media that places the importance on communicating in a Pathos (emotive) form. Propaganda has been used in a multitude of ways; from campaigns to promote vaccines to campaigns that promoted fascism. We would be using propaganda in the former fashion, one that does not seek to fear-monger, but rather to build confidence and promote a trust for the program.  

[6] And minimal invasive plants.

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