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Posted by: Write My Essay on: May 14, 2019

Write My Essay Sample: Stormwater

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Abstract

Utilizing a qualitative framework for analysis, this study will focus on examining the different proposed solutions for resolving the environmental damage associated with levees and stormwater runoffs. This is due to the unnatural method in which water is pumped into rivers during storms which can radically alter the chemical composition, temperature and delicate nutrient balance in the water within a short period. Levees also act as an effective barrier towards preventing the water from returning properly into the soil. As a result, stormwater runoffs and levees can contribute towards the gradual deterioration of biospheres within particular areas which requires intervention due to the long term damage this could cause. However, there are several potential solutions to choose from, each with their pros and cons to consider. As such, this paper will investigate these methods, examine their individual effectiveness and determine which one has the highest level of viability.

Evaluation of Role of Levees and Floodplain Management

Introduction

Expansive urban and industrial development often places considerable stress on local ecological systems resulting in an altered biotic environment that makes it unsuitable for particular types of flora and fauna to exist within it. Rivers and streams that straddle levees located near cities and industrial development areas are considered to be particularly vulnerable given their closer proximity to pollutants and other agents of change (Booth, Roy, Smith, & Capps, 2016).  One of the most common contributing factors when it comes to such actions are the stormwater runoffs that flow from a city or industrial development project and into rivers with levees (Halstead, Kliman, Berheide, Chaucer, & Cock-Esteb, 2014). Due to the lack of any natural methods of dealing with the sheer amount of water from storms, many cities and industrial sites often have storm drains that lead to pumping stations which quickly shunts water away from their location and into local tributaries and streams. Unfortunately, these methods often contribute towards the gradual deterioration of the ecosystem in the river. While there are some proposed methods for dealing with this, there needs to be a greater focus on a method that explicitly takes into account stormwater runoffs and not just the effect of levees on rivers.  As a result of the differing proposed methods, the conflicting perspectives behind why they should be implemented, and the likelihood of budget shortfalls within cities that would prevent all of them from being implemented, it is necessary to determine which method is likely the most viable. To determine this, the paper would need to examine the basis behind each proposed approach and determine their individual effectiveness when compared to each other.

Objectives/Aims

The proposed solution to the problem surrounding stormwater runoffs causing urban stream syndrome should be able to:

a.) Resolve the issue surrounding altered channel morphology

b.) Be able to help sustain the biotic richness of the river/stream

c.) Preserve the capacity for current runoff systems to continue to operate to prevent flooding within a city or industrial district.

By matching these objectives, the proposed solution would be able to succeed in its indicated goal.

Understanding the Issue

The problem with stormwater runoffs and levees is that they can cause severe alterations in the biochemical composition of rivers resulting in an adversely affected biosphere. Various levees located near cities can contribute to the problem by virtue of a lack of sufficient foresight in their construction which can lead to long-term environmental instability. Unfortunately, due to the unnatural method in which water is added into these ecosystems via stormwater runoff drains, this can drastically alter the chemical composition, temperature and delicate nutrient balance in the water (Vietz, Walsh, & Fletcher, 2016). The problem lies in the increased water speed that levees create, the resulting deterioration of beneficial vegetation within the stream, and the sheer amount of water that is forced into the streams/rivers via storm drains. Rivers and streams simply cannot cope with the runoff of an entire city being added within a short period. [“Write my essay for me?” Get help here.]

There are, of course, proposed solutions to such a problem ranging from dispersed stormwater treatment, habitat enhancement within the stream itself, to adding in robust vegetation in selected areas to boost the ability of the body of water to repair itself and protect more vulnerable flora and fauna (Askarizadeh, Rippy, Fletcher, Feldman, Jian, Bowler, & Grant, 2015). Each proposed method has its pros and cons given their respective viabilities and the inherent cost of implementation.

Due to the different proposed methods, this paper will seek to critique the most popular proposed methods of resolving the issue. Through this analysis, this paper will be able to showcase the superiority or inferiority of particular solutions, present arguments for or against their implementation and determine which method is likely the most viable based on the information that will be shown.

Literature Review

Understanding the Impact of Land Use on Biodiversity

Biodiversity is inherently influenced by its surrounding landscape with alterations often leading to instances of decreased ecological functionality. While protecting biodiversity may not be at the forefront of a designer’s mind when it comes to designing levees to protect areas that are prone to flooding or implementing a system to deal with a city’s stormwater runoff, it should be, due to the long-term ecological damage that this lack of foresight could cause to the surrounding area.

Present day stormwater runoff designs are often utilized in conjunction with levee construction to quickly shift water away from a city’s streets and onto areas that can handle the flow. One of the best examples of this can be seen in Japan where an extensive system of levees and stormwater runoff control measures are located. Local rivers and tributaries are often the sites chosen for this endeavor given their capacity to contain the spillage and transfer it to another location. However, as it has been noted in the introductory section of this paper, the sudden introduction of thousands of gallons of water within a short period into the ecosystem of a river, substantially alters its chemical composition and temperature. The result is the inability of a river’s original ecosystem to cope, consequently resulting in its gradual deterioration (Sartor et al.,, 1987).

Unfortunately, the long-term consequences of these actions on a river’s morphology manifest adversely and can be seen in the case of various rivers and streams located near Chinese cities with levees and storm water runoffs. The altered river ecosystem resulted in many plant and animal species dying off. Additionally it has led to the rise of undesirable green algae and the accumulation of different pollutants within the river due to hindrance in its natural ability to remove it. During summer months, when the algae tends to accumulate and decay in vast quantities, many residents complain of an undesirable stench permeating the area.

In the long term, the lack of floodplains and the way in which the levees were constructed results in silt and various detritus slowly accumulating along the bottom of the river. This results in its gradual elevation until it reaches a point where the material, which contributes towards the pollution and stench originating from the river, has to be manually removed to prevent potential flooding (Gaffield et al., 2003). All these examples show the consequences of altered river morphology. It is essential that we take into account the role of  levees in mitigating adverse impact due to altered river morphology and stormwater runoff construction needs.

Strategies to Resolve the Issue

Proposed below are various strategies to resolve the issues surrounding the ecological impact due to  altered river morphology. Each has its own unique merits and demerits on what can be done to address the issue.

a.) Artificial Waterways to Preserve River Biodiversity

One proposed method is to create artificial waterways alongside current river systems to help preserve the native biosphere in that location (Sedaghatdoost & Ebrahimian, 2015). For example, river Ems in North Western Germany where the native ecosystem thrives in enclosed canals with a built-in artificial waterways. The process works via a series of levees and canals that would be constructed parallel to the current system that is in place within the river (Scott et al., 2014).

In some cases, during storms, a gate would slide into place that would help insulate the ecosystem within that particular area from the sudden deluge of stormwater. By putting these canals along select areas in the river, it is hoped that this would ensure that the native ecosystem would be able to survive and thrive within the local area. However, while this process helps to protect some of the native species, there are some caveats to this approach that should be taken into consideration.

The first issue is that, this process will result into  buildup of silt and other substances along the riverbed. Evidence of this can be seen in the numerous reports stating the deteriorating water quality along the river Ems. As it can be seen in the photo below, the river is uniformly brown which is indicative of a high amount of sediment and particulates in the water (Fig. 1). This is due to the lack of floodplains to dissipate the strength of the river’s flow, the presence of pollutants from stormwater runoffs from cities located near the river, and the accumulation of materials along its bottom (Walsh et al., 2016). [Need an essay writing service? Find help here.]

Aside from this, the canals would only help to insulate certain sections of the river and does not resolve the potential problem of native ecosystems being overwhelmed by these pollutants, if they were to make their way into the canals.

Figure 1: River Ems, North Western Germany: Main River (right) and Canal (left)

b.) Planting Trees and Other Types of Fauna

Planting trees is one of the proposed solutions to help mitigate ecosystem destruction in areas with storm drains and extensive levees. Particularly the trees with long roots do create natural barriers for small fish and fauna. This approach is based on the perceived effectiveness of the system in Germany, Brazil, and other countries who planted trees along rivers to help prevent flooding in various parts.

While this system has proved to be effective in at least partially preventing the erosion caused by increased water flow from stormwater overflows, it came with its own set of problems. The problem with tree roots is that they can damage the structural integrity off levees by providing pathways for water to destabilize the soil. In the long term, this can impact the ability of the levee to perform its function resulting in a breach which could potentially flood an unprotected area (Christensen et al., 2006).

Aside from this, the proposed solution does not resolve the temperature and chemical changes that occur when stormwater runoffs are introduced in the river. While the tree roots help to create a protective barrier, various fish and fauna can still be affected by the chemical imbalance.

c.) Removal of Levees to create new Floodplains

Due to the long-term ecological damage brought about by stormwater drains and levees, removal of levees and  creating new floodplains within certain areas seems to be a plausible approach. While somewhat effective in preventing floods, levees can also adversely affect the local environment. After they are constructed, levees can reduce the recharge rates of local aquifers and even prevent the seasonal over flooding of banks that are essential in providing much-needed nutrients to the soil (Christensen et al., 2006).

This can lead to the destruction of riparian and coastal ecosystems within certain locations which can lead to permanent ecological damage. However, these actions are considered as justified due to the perceived need for expansion into new areas for housing and city development.

Unfortunately, as seen in the case of the Ems River in Germany, lack of floodplains prevents the proper exchange of energy and nutrients between the river and the surrounding land which leads to a deterioration of the river as a whole. Combined with stormwater runoffs and the increased movement speed of the water due to the levees, this interferes with normal plant distribution via seeds in the river, prevents river vegetation from properly establishing itself, and leads to an excessive buildup of sedimentation with the river which increases the risk of flood (Petrucci et al., 2012).

The impact of this on fauna within the river can be seen in reduced fish populations due to the lack of sufficient oxygen in the water. The lack of vegetation combined with cloudy water due to excessive particulates reduces atmospheric diffusion of oxygen resulting in depleted dissolved oxygen level that may not be conducive  for fish to thrive. All of these factors show why levees can do more harm than good if they are constructed with insufficient foresight regarding their potential ecological impact (Petrucci et al., 2012). To resolve this issue, the proposal of removing levees seeks to return certain areas back into their previous state of affairs by transforming them back into floodplains and wetlands.

Through the restoration of these areas in certain locations along the river would help in reducing the excessive flow rate generated by levees that would serve as an important  sediment and pollution control mechanisms. For example, numerous floodplains in the Nile River which helps to enrich the land while at the same time lower the speed of the river as a whole due to the presence of levees in certain areas. While this approach may seem to be the most effective, it is also likely to receive the greatest amount of resistance. Many real estate developers and residents are unlikely willing to relocate due to the need to restore a previously destroyed floodplain.

d.) Implementing Artificial Methods of Flooding Floodplains

Another potential alternative solution that can be pursued is to create a levee design that feeds into a temporary floodplain via a special gate located within the levees. As mentioned earlier, floodplains help to alleviate the strength of a river’s flow while at the same time act as a means of filtering out excess sediment and pollutants within the river (Wadzuk et al.,  2010). A temporary floodgate design would create a schedule where the floodgates would be open during a particular timeframe to help alleviate the stress placed on the river and then closed once it has been determined that a sufficient amount of water has been removed.

This design addresses the issue of sediment buildup and resolves many of the issues surrounding levee designs interfering with local ecological systems. For example, in Egypt where an extensive system of levees and floodgates have been used for years to prevent flooding while at the same time allowing enough water into the floodplains to ensure that they remain nutrient rich (Lapointe et al.,  2012). During periods where there is significant stormwater runoff during inclement weather, the floodgates can be opened to help alleviate the excess amount of water that appears during this particular period.

While this design may seem to resolve many of the issues that have been presented in this paper so far, there are some problems that should be taken into consideration. The first is whether newly reconstructed floodplains would be able to handle the excess capacity from stormwater runoffs. These floodplains initially designed to process average water intakes when a river overflowed and was not exposed to the sheer amount of water that is often the result of storm drains unleashing thousands of gallons of water within a short period.

There is a high probability of the floodplains being overwhelmed resulting in the water spreading into populated areas within a short amount of time. Aside from this, such a system would need to allocate large amounts of land for a floodplain to be effective; however, this may not be an option when it comes to levees and stormwater runoffs that are located near cities since there is a limited amount of space available within the surrounding area (Break this into two separate sentences) (Redaelli et al.,  2011).

Furthermore, it is still uncertain whether such a solution would help in resolving the ecological problems brought about by stormwater runoffs and levees. As discussed, it does address the build up of mud and sediment and contributes to alleviating the pressure on the river, but how would such a solution help the local fauna? Simply draining the river into a floodplain has the potential effect of causing various types of water-based fauna to eventually find themselves on dry land which would result in another form of ecological damage. Such a solutions need a thorough examination before advocating its use in any kind of long-term river ecosystem management.

e.) Underground Concrete Tunnels and Canals for Stormwater

One of the potential alternatives to the issue is to avoid having the waste water go directly into areas in the river which have been identified as having critical ecological habitat. The underground discharge channel with a pumping station that can transfer the water to a location farther down the river with a sparse ecosystem. For example, in Kasukabe, Saitama (Japan) where a large underground complex of tunnels and pumping stations helped displace thousands of gallons of water into the Edo River once a storm affects the city.

The advantage of this method is that, through the construction of an appropriate system of tunnels and canals within the city, it can completely avoid critical areas in the river. While this system is likely to be the most effective option among the proposed methods, it is also the most expensive to implement given the sheer amount of money needed to construct an underground system of canals, tunnels and pumping stations (Kaczala et al., 2011). Due to the funding that such a venture would entail, it is unlikely that various cities and towns would agree to fund the venture despite its potential ecological boons.

Summary and Examination

We have discussed the most popular proposals for proper environmental management of rivers. Each proposed solution has its own pros and cons such as the viability of the concept, the inherent limitations based upon the location of the river and the stormwater runoffs as well as the financial hindrances behind their implementation. However, what is lacking in this section is an examination of how such processes work when implemented in an actual project and the long-term implications behind their usage.

As seen in the case of the Ems River in Germany and the Nile River in Egypt, environmental river management strategies can result in widely different outcomes which can have an impact on the health of the river and the ecosystem that exists within it. As such, the analysis section of this study will compare the use of these methods on different rivers and determine which method has the greater likelihood of success based on its fiscal viability and actual performance when implemented.

It is anticipated that the results would  reveal weaknesses in the proposed methods that were not shown in the literature review and determine which method or combination of methods is likely to generate the desired outcome of environmental preservation while not compromising the function of levees and stormwater runoff systems.

Analysis

Introduction

This section delves into the present day examples of preserving the ecology of a river by mitigating the effects of stormwater runoffs. It expands on the methods that were mentioned in the literature review by showcasing the effectiveness of these systems within various states in the U.S. as well as in other countries around the world. It examines the correlation between levee construction, its impact on river ecology, issues regarding river hydraulics, and the effectiveness of particular strategies.

The goal of this section is to show how the proposed methods that were elaborated on in the literature review section have their own caveats that reduce their effectiveness on a case by case basis. For example, while underground tunnel systems can mitigate stormwater runoffs by having the water flow to a local river basin and, as a result, are an effective means of safeguarding the ecology of a river, they are cost prohibitive in some cases and take far too long to construct.

This example is aligned with the main argument of this report that there is no such thing as a “one size fits all” solution in resolving the impact of stormwater runoffs on the ecology of a river. Some methods may not be feasible and, as such, blended strategies may be necessary by modifying that is presently known about levee construction, stormwater runoff dispersal, and floodplain management.

It is anticipated that by the end of this section, readers will realize the complexity of the issue where engineers need to balance ecological preservation while dealing with the communities situated along rivers that contribute towards their gradual destruction.

Examining the Use of Artificial Waterways to Address River Biodiversity

The main problem with human expansion into areas bordering streams and rivers is that it results in a process called eutrophication which is defined as the deterioration of bodies of water which manifests as a gradual decline in their life spans. Actions such as the construction of artificial levees to stem the flow of water, the placement of rudimentary rock dams to alter river morphology as well as the deforestation of certain areas to make way for housing development all contribute towards eutrophication (Dotto, Kleidorfer, Deletic, Rauch, & McCarthy, 2014).

This process is especially prevalent in various areas in California wherein the results of eutrophication has caused an unnatural “explosion” of algae in rivers which has significantly decreased the quality of local water systems. Contributing to this issue are the various problems related to stormwater runoffs that have been mentioned so far in this report (ex: altered river biochemistry and rapid changes in temperature). One of the proposed methods of resolving this issue comes in the form of creating artificial waterways near river littoral zones to act as a means of insulating flora and fauna from sudden alterations.

As seen in the case of the river Ems in Germany, the process works by constructing an artificial levee along the littoral zone several meters away from the riverbank where stormwater drains are located. This artificial levee acts as a riparian corridor which is a strip of land whose physical characteristics are inherently influenced by the bodies of running water that they are located near to. It looks like an elongated island that is filled with trees and other shrubberies which function as an insulator within the river (Dotto et al., 2014).

Stormwater runoffs enter into a particular waterway and are prevented from interacting with the body of water on the other side of the artificial levee. In various instances in Germany and the Netherlands, this has proven to be a somewhat effective system of artificial insulation to help preserve river biodiversity. However, it has not been proven to be 100 percent effective as seen in the case of the river Ems due to the inherent limitations in artificial levee and riparian zone creation.

While particular areas within a river can be insulated from direct stormwater runoffs, the waterways do intersect downstream which can negatively impact the biodiversity in those areas. Aside from this, the utilization of this strategy is inherently limited by local geography and even the water conditions in certain areas. For example, the Klamath River in California was once considered the third highest producer of Pacific Salmon in the U.S.; however, due to a combination of stormwater runoffs from the local hydroelectric dams, prolonged seasonal droughts and waste water from extensive agricultural operations, this body of water is now increasingly becoming unsuitable for Klamath River Salmon which is leading to their extinction (Sedaghatdoost & Ebrahimian, 2015).

The problem with implementing an artificial waterway to stem the impact of stormwater runoffs from the hydroelectric dams and agricultural operations in the area is the general shape of the Klamath River in particular places which straddles various mountain ranges creating a naturally twisting corridor (Sedaghatdoost & Ebrahimian, 2015). As a result, artificial levees and riparian zones cannot be constructed. The extended seasonal droughts that California has been experiencing over the past few years also prevents the creation of artificial waterways along the Klamath River due to the lower water levels.

Contributing to this problem is the process of eutrophication along the bank of the river which has gradually deteriorated the quality of the riverbank. Unfortunately, these combined problems have created a river that has increased levels of algae, high nitrate content from the agricultural farms and sudden shifts in chemical composition and temperature when the four hydroelectric dams in the area release their excess water flow during storms.

What this example shows is that the creation of artificial waterways to solve the problem of river biodiversity is only applicable in cases when the river is located in areas that are sufficiently broad and have an accommodating geography. Areas like the Ems River in Germany and the Nile River in Egypt fulfill this criterion but in the case of the Klamath River, this is not applicable.

Planting Trees and Other Types of Fauna

Using deep-rooted trees as a means of mitigating stormwater runoffs to protect the ecosystem within bodies of water has become an increasingly popular solution due its cost effectiveness and apparently positive results. Sites like the Chickley River in Massachusets and the Ottauquechee and Black rivers in Vermont have all received extensive planting projects with thousands of trees being placed on their riverbanks and levees (Giacomoni, Gomez, & Berglund, 2014). Deep-rooted trees have been shown to mitigate stormwater runoffs due to their roots acting as a form of natural breakwater within the river to help reduce the water flow and act as a natural means of absorbing pollutants. Not only that but the roots also serve as a natural habitat for the local fauna and even encourage the growth and development of various flora.

The roots also assist in absorbing excess carbon dioxide from the water resulting in better water quality which helps the ecosystem to thrive. However, the problem with their extensive use in areas with human-made levees is that studies proving or disproving the potential deterioration of levees due tree roots are still inconclusive. Studies examining the damage seen in levees during violent storms as well as those utilizing LiDAR and hyperspectral imagery have mixed results with one showing damage to levees and the other showing no damage at all (Jiake, Ya, Jiayang, Huaien, & Yajiao, 2016).

The problem with these studies is that they are based on recent projects involving tree plantings along rivers. In these cases, the tree roots have yet to develop an extensive enough network to compromise the stability of manmade levees. Though various environmental groups have argued that tree roots help to stabilize levees rather than cause damage. There are simply not enough studies at the present to create a valid conclusion on this issue and, as such, it would be necessary to conduct long-term examinations of areas where extensive tree plantings have occurred to determine if the levees in those places have been structurally compromised by tree roots (Dallman & Spongberg, 2012).

Another issue to discuss is that while tree roots act as practical barriers within rivers to help stabilize the speed of the water during extensive stormwater runoff periods, they do not serve as a means of preventing the sudden changes in temperature or the chemical composition of the river. While it can be argued that the tree roots help to mitigate the development of extensive sediment and other detritus along the banks of the river, they lack the same capacity to insulate flora and fauna from the direct impact of stormwater runoffs when compared to artificial waterways. However, planting trees is a far more adaptable and cost effective solution compared to creating an artificial waterway.

The only problem with their extensive implementation, as mentioned extensively in this section, is that their long-term effects on levee structural stability are still unknown and, as such, it would be unwise to advocate for their extensive use unless it has been proven there is no danger to residents, especially those in areas with levees protecting low-lying areas.

Implementing Artificial Methods of Flooding Drained Floodplains

Artificial flooding is not a new concept since it has been used in examples such as the Fitzroy River in Australia and the Coldwater River in Mississippi. The concept is based on alleviating water pressure by creating a floodgate in a levee to help relieve the excess water flow in a river when stormwater runoffs occur. The implementation of this plan has two beneficial outputs; the first is the rehabilitation of closed-off floodplains that were sealed way during levee construction as well as the limitation of the impact of stormwater runoffs on aquatic ecosystems in the river (Steinman, Isely, & Thompson, 2015). By shifting the thousands of gallons of rainwater into a floodplain, this helps to enrich the land and reduces the amount of sediment and other detritus from accumulating along the bottom of the river.

Examples of this process in action can be seen in the Nile River in Egypt as well as the Coldwater Water River in Mississipi. In both cases, the use of a floodgate system proved to be sufficiently effective in reducing the impact of stormwater on the river. This was evidenced by decreased particulates in both rivers in tests done after the excess water has abated, the stabilization of water quality, and improved conditions for aquatic flora and fauna to exist. However, before such a tactic is implemented, there are some caveats to this approach that should be taken into consideration.

The first is the availability of space in which this can be viably implemented. In the case of the Coldwater River in the U.S., nearly 2.5 kilometers were allocated for the rehabilitation of a floodplain via the construction of a floodgate for the river water. In the case of the Nile River, many gates are utilized, and the amount of land that they cover is more extensive (three kilometers or more) (Howitt, Mondon, Mitchell, Kidd, & Eshelman, 2014). This is due to the necessity of sufficient water distribution and the presence of local aquifers in the ground that can handle the excess water. If these conditions are not met, the result is a sustained flood rather than gradual water absorption. It is due to this limitation that various areas within the U.S. cannot implement such a strategy since the areas where the floodplains used to be have been urbanized and now contain new populations.

While it can be argued that new sectors can be utilized as floodplains, they need to have the factors that were brought up earlier (ex: the presence of aquifers). Without those elements in place, the artificial floodplain is unlikely to function appropriately and may even cause more harm than good. Aside from this, there is also the issue of levee hydraulics and the capacity of levee designs to accommodate the introduction of a floodgate to revive a floodplain. Levees are meant to protect against the proposed recreation of floodplains and, as such, present day designs may not be advisable for a simple modification to accommodate a floodgate. Project managers utilizing this method would need to consider how to implement a system that incorporates proper hydraulics to limit the flow of water while at the same time preserving the integrity of the surrounding levees.

Removal of Levees to Create new Floodplains

Removing levees to resolve the problems surrounding stormwater runoffs may seem to be a counter-intuitive solution; however, it does have a justifiable methodology behind it. Levees are not perfect performers when it comes to the jobs they are meant for. While this may seem to be an absurd assertion, various studies and even experts in the field of levee construction will tell you that levees are simply not sufficiently designed to prevent every conceivable type of flood. If you are after the creation of a construct that could potentially protect an area from what can be defined as a “maximum worst-case flooding scenario” then the best solution would be to create a dam. However, given their size, the inherent cost of their construction and the limited areas in which they can be effective, dams are not a feasible in every case. For example, it would be impossible to build a dam all along the Mississippi River given its sheer size.

The problem though with the creation of levees is that they often help to cause flooding rather than prevent it. Evidence of this can be seen in the case of the Mississippi watershed and the various warnings from experts that precipitation and snowmelt pattern changes brought about through anthropogenic climate change is contributing towards creating a high-risk scenario of levees being breached due to higher than average flood waters (Elliott & Trowsdale, 2007). Contributing to this problem is the placement of stormwater runoff drains from cities in the state that utilizes the Mississippi River as their primary offloading site. This contributes to the sudden rise of potential floodwaters during storms and puts numerous populated areas located all along the Mississippi River at risk.

Aside from this, the combination of closed off floodplains by levees and stormwater runoffs has caused substantial damage to the ecology within the river. This comes in the form of increased algae production, sediment buildup, and greater river strength which prevents certain aquatic flora from being able to sufficiently develop (Hamel, Daly, & Fletcher, 2013). If these problems seem familiar, it is because they have been mentioned numerous times throughout this report in conjunction with the presence of levees and the unnatural alterations done to a river’s morphology and hydraulics due to urban developments along areas that used to act as floodplains.

Further analysis of this issue shows that the problem stems from the urbanization of floodplains located along the Mississippi which prevents the river from having adequate areas to offload its excess contents. As a result, water naturally accumulates which creates an increased risk of catastrophic flooding. The obvious solution to this dilemma would be to open up certain areas by removing levees to reinstate the floodplains. Unfortunately, given the presence of communities in these locations, this is simply not an option in a lot of the affected areas in Mississippi (Elliott & Trowsdale, 2007).

This solution may be applicable in other places in the U.S. such as in California and Arizona where there are fewer communities located along floodplains. Based on what has been presented so far, this solution is highly dependent on communities being located away from areas where floodplains are. In fact, the best solution to issues like this that creates the potential risk of catastrophic flooding and adversely impacted river ecology is to simply stop building communities along floodplains (Maniquiz-Redillas, & Kim, 2016). If this policy were to be implemented, this would go a long way towards lowering the impact of stormwater runoffs into rivers as well as addressing the environmental issues associated with closed off floodplains.

Underground Concrete Tunnels and Canals for Stormwater

As mentioned earlier in this paper, underground flood tunnels are one of the most efficient methods of dealing with stormwater runoffs since they are capable of storing and diverting the water in areas that are further downstream. As a result, this helps to minimize their overall ecological impact and contributes to preserving river morphology, hydraulics, and health. Unfortunately, the main issue that most areas would encounter when attempting to implement such a system is the inherent cost and time associated with their construction (Ren & Smith, 2012).

For example, the underground flood tunnels in Saitama, Japan that was mentioned earlier on in this paper cost the country $3 billion dollars to construct. In the U.S., a similar system was implemented in San Antonio, Texas which cost the state $150 million dollars (Ren & Smith, 2012). What this shows is that while the system is effective in dealing with stormwater runoffs and helps to protect the environment, its construction is not cost-effective, at least when it comes to areas with limited budgets. There is also the period required to implement such a system since the underground flood tunnels constructed in San Antonio took 13 years to build (Ren & Smith, 2012). In some places, the sheer amount of time needed to implement such a solution to resolving the impact of stormwater runoffs in a river is simply too long.

By the time the system has been constructed and put into use, the morphology and health of the river could have been irreparably damaged. However, this type of solution also comes with its own caveats if it is not implemented properly. If the outflow system used for the underground tunnels is not designed properly, then it may cause the downstream bank erosion and lead to the gradual destruction of the local environment. Not only that, if the flow is not regulated, it could cause a significant impact on the balance of sedimentation of the river which could further disrupt a river’s ecology. The system in San Antonio, Texas has mitigated these potential issues by situating the exit tunnels close to river basins which help to reduce the overall environmental impact of the flow of water. Unfortunately, this method of implementation is successful only in a case by case basis as seen in the detrimental effects of the New York underground flood mitigation system which exists directly into the Hudson River which has caused a permanent adverse effect on the surrounding ecology.

Summary

Overall, what this section has shown is that there is no such thing as a “one size fits all” strategy when it comes to preserving the ecology and morphology of a river due to stormwater runoffs. Ranging from issues with geographic features to the fixed costs associated with certain processes, the methods that have been mentioned in this report showcase a myriad of pros and cons with their use.

While some show significant potential, such as the use of deep-rooted trees, the lack of present day understanding regarding the long-term impact of such a strategy on the structural integrity of levees ensures that there will always be some degree of hesitance if not outright resistance behind its use. Based on the varied effectiveness of the strategies that have been presented so far, this report advocates for the creation of blended implementation methods that combines the strengths of the different strategies involved while potentially mitigating their weaknesses. What these potential strategies can be will be elaborated on in the discussion chapter of this report.

Discussion

Introduction:  Blended Strategies to Mitigate the Ecological Impact of Stormwater Runoffs

This section is aligned with the main argument of this report that there is no such thing as a “one size fits all” solution in resolving the impact of stormwater runoffs on the ecology of a river. Some methods may not be feasible and, as such, blended strategies are necessary to address the problem of stormwater runoffs by modifying what is presently known about levee construction, stormwater runoff dispersal, and floodplain management. It is anticipated that by the end of this section, readers will realize the complexity of the issue and the need to implement new strategies rather than rely on current methods that have variable levels of effectiveness.

Water Intersection and Floodplain Management

In the analysis portion of this report, it was revealed that the use of artificial waterways to address the issue of adversely affected river biodiversity is only partially effective since instead of changing the morphology of the river in one section, the negative impacts are directly carried downstream. It was shown that the problem is the intersection of different water sources (e.g. from the river and stormwater drains), and the resulting changes in temperature, chemical balance and the altered speed of the river itself. While one proposed solution to this dilemma is created longer artificial waterways, it is not viable given the associated construction costs and the fact that the stormwater runoff will eventually be dumped in the river. Utilizing the premise of this report that blended strategies are necessary to resolve the issue, albeit, in an economically sound manner, one potential route that can be taken is for the stormwater to be diverted to a floodplain prior to it being introduced into the river.  This idea is based on the methodology utilized in the city of Scottsdale and their stormwater and floodplain management system that implements a series of drains placed into the floodplain itself to help drain water from storms into rivers for dispersal.

Figure 2: Floodplain Dispersal Method

This type of process works by having the stormwater released into the floodplain instead of directly into the river. The justification for this method is that the broad floodplain would help to decrease the speed of the water as it enters the stream, stabilize the temperature to a more acceptable level and reduce the potential for substances from the runoff affecting the chemical balance of the river water. Drains located in various areas both on top of the floodplain and below it would help to slowly disperse the water into different areas along the meander scars of the river (or the undercut bank) resulting in a transition that is more ecologically “acceptable” rather than dumping the water straight in.

What occurs is that the floodplain acts as a filter and location for the stormwater runoff, this helps to mitigate many of the potential problems associated with dumping the water directly into the river. Aside from this, the floodplain also contributes to lowering the total amount of water that does make it into the river since it helps to refill the aquifers that are located beneath it. There are, of course, limitations to this particular system such as the size of the floodplain, its capacity to hold water and the increased amount of sediment that would enter into the river over time. The gradual erosion of the soil could be a problem in the long term since replenishing the top soil is not feasible.

One way of resolving this potential issue is by breaking up the distribution of water along separate sections of the floodplain. This helps to slowdown the flow of the water and enables the floodplain to recover. This strategy is not widely used since floodplains are often thought of as places where water from a river goes to rather than the opposite occurring. However, as seen in the case of Scottsdale, this method can work to preserve the ecology of a river by mitigating many of the associated factors that would adversely affect flora and fauna within it (Davis, Brown, & Dinnin, 2007). This is one of the cases where an artificial floodplain would work since what is needed is a method of filtration, temperature normalization, the removal of chemicals and a means of slowing down the water.

While the presence of aquifers would be beneficial, they are not strictly necessary for the implementation of this type of project. What is also needed in this case is a levee design that allows movement of the water from the floodplain into the river than the opposite occurring. Various elevated levees with water runoffs located in specific areas could be utilized to this end; however, there would need to be some means for the water runoff valves to be controlled to prevent water from the river entering into them if a major flood occurs.

Enhancing Artificial Floodplain Creation Through the Use of Flora

As mentioned in the literature review section and in the analysis section of this report, artificial flooding is not a new concept since it has been used in examples such as the Fitzroy River in Australia and the Coldwater River in Mississippi. The concept is based on alleviating water pressure by creating a floodgate in a levee to help relieve the excess water flow in a river when stormwater runoffs occur. However, the biggest problem with this solution is the necessity of sufficient water distribution and the presence of local aquifers in the ground that can handle the excess water. If these conditions are not met, the result is a sustained flood rather than gradual water absorption.

While the concept of an artificial floodplain to help mitigate the excess water produced by stormwater runoffs does have a considerable amount of feasibility, unless the water distribution issue is solved, it is not sufficiently viable. Do note that this solution is different from what was mentioned earlier involving stormwater runoffs and floodplains since, in the previous blended solution, the runoff does go into the river and, as such, a sustained flood does not occur. Going back to the premise of this paper that blended solutions are needed to resolve the issue rather than rely entirely on present day methods, one potential avenue of approach combines the creation of artificial floodplains with planting different types of trees and other types of similar flora.

This method is based on the flood control protocols implemented in Tacloban in the Philippines where various forests have been created in artificial floodplains to help contain river overflows during, particularly harsh storms. This method builds upon the previous practice of planting trees along river banks and instead focuses on a larger scale solution utilizing artificial flood plains. The idea is that the dense trees and other types of flora in that area can act as a means of absorbing the water till the flood waters subside, or some of the water is absorbed into the ground. This strategy builds upon the method utilized in the Philippines by adding in a levee that can allow some water from the river to flow into the floodplain thereby minimizing the overall effects of the stormwater runoff (Wagner & Zalewski, 2016).

Another solution would be to utilize the same methodology that was mentioned in the previous strategy wherein stormwater runoffs would flow directly from storm drains directly into the artificial flood plain so that at least some of the water can be absorbed by the the trees and surrounding flora before it seeps into the ground and is drained into the river. Either solution has the potential to at least partially resolve the problem of stormwater runoffs causing substantial ecological damage.

Underground Canals and Floodplains

Another potential solution is the combination of underground canals and floodplains wherein instead of the water going directly into the river; the water would go through the underground canal system within a city and be deposited in a floodplain or lake that is sufficient far way. There is ample precedent for this scheme as seen in the case of the Philippines and Laguna lake wherein a large artificial canal system is being built to transfer water from the city, into the canal and away from many nearby rivers or streams. For this report, the proposed blended solution focuses on floodplains that have not been inundated with urban or suburban development and are, for the post part, untouched.

These areas are ideal since they are likely to already have natural aquifers in the ground which can help to mitigate the water released from the canals. This solution is has a considerable level of potential since it addresses the chemical, temperature and particular pollution that is typically associated with stormwater runoffs by having it go through a still operational floodplain that is located far away. In fact, this solution could even be enhanced through the introduced of various trees and different types of flora that can help to absorb the excess stormwater. While on the surface this proposed solution has a lot of promise, there are some issues that should be taken into consideration. The first problem is the sheer cost and time needed to construction underground water canals.

As seen in the examples in the literature review and in the analysis section of the study, the development can take 15 years or more and could cost hundreds of millions of dollars. Creating an extended channel that is supposed to dump the water into a viable floodplain is also going to substantially increase the cost of the operation. However, given the potential that such a strategy has, it could be implemented in cities where there are already existing channels in place. Austin, Texas already has an extensive canal system in place for storms and all that would be needed would be to extend the canal to dump the water into a floodplain instead of directly into the river.

Analysis of Solutions

This report asserts that though the blended strategies that were developed show a lot of potential in resolving environmental issues caused by stormwater runoffs, they are applicable in only a limited number of cases. In the case of utilizing floodplains as a means of filtering water and slowing it down before it reaches the river, this strategy is highly dependent on the actual presence of a floodplain located nearby. In some cases, due to extensive urban development, floodplains are no longer available which makes this particular solution nearly impossible to implement. For example, due to extensive development in some areas along the banks of the Mississipi River, the floodplains that used to be located along the curve of the river are now towns and factories.

While artificial floodplains could potentially be created down the river to resolve the issue, this does not have a high level of viability given the potential lack of aquifers, the unsuitability of the land, the need to reconstruction stormwater runoff systems and an assortment of other issues that may occur. This shows an inherent weakness in this strategy that cannot be easily overcome. In the case of using trees to help mitigate the flow of water into the river by planting them in clusters along floodplains, this does have a high level of viability, but the problem with this strategy is that it can take years before it comes to fruition. Trees take time to sufficiently mature, and this is if the area that they have been planted in does not undergo drastic environmental changes that could negatively impact their growth rate (ex: sudden flooding).             Underground channels to help deal with the excess water does have a significant level of promise; however, as mentioned earlier, they are cost prohibitive, and there are some areas that are not suitable for their use. For example, in the case of New Orleans, the land underneath the city is compromised of relatively weak chalky ground that is not appropriate to hold up large structures. This is one of the reasons why zoning permits for high-rises in the city are limited to only certain areas since the ground is simply too weak to accommodate these large structures. The same can be said about constructing an extensive underground canal system since it is likely to weaken the underlying strata of the surrounding land to such an extent that it could lead to a major catastrophe.

What all of these alternative solutions show is that their implementation is highly dependent on the geography of the land that they are situated on. In some cases, the proposed solutions are not feasible given the inherent limitations of time, geography and potential exorbitant cost.

Summary

Overall, the designs that were developed focused on mitigating the chemical, temperature and sudden influx of water in this section of this study have shown the potential effectiveness of blended solutions when it comes to preserving the ecology of a river while at the same time tackling the issue of stormwater runoff management. This report would like to reiterate that there is no such thing as a “one size fits all” solution and that the proposed blended strategies are only some of what could potentially be implemented in the future.

There are a wide array of other possible solutions that can be implemented ranging from creating underground rivers or even diverting rivers from their normal flow patterns so that a particular area can be devoted for stormwater runoffs. What this report sought to show is that alternative solutions can be pursued that take into consideration the environmental impact of stormwater runoffs. This indicates that a multipurpose design is possible, plausible and can be implemented utilizing present construction techniques.

Based on what has been examined so far, this report assumes that the problem with present day designs is that engineers are focusing more on flood management rather than environmental preservation which has resulted in the current dilemma faced by various river ecosystems. Resolving such an issue by future studies would thus focus on determining how such an attitude has developed among engineers, whether project cost factors influence the implementation of environmentally sustainable designs and what are the current perspectives of engineers on river sustainability. By understanding their motivations, future papers would be able to determine what sort of strategies could be implemented to promote environmentally sustainable designs for stormwater runoffs.

Conclusion

In summary, what this report was able to show is that the differing proposed methods of resolving the issue of stormwater runoffs negatively impacting the ecology of a river lacking sufficient effectiveness is based on the fact that present day solutions are oriented towards flood prevention rather than purely environmental preservation. While there have examples presented in this paper where environmental protection practices have been implemented,  the conflicting perspectives behind why they should be used, and the likelihood of budget shortfalls within cities, prevent many of them from being feasibly implemented.

To determine how such a problem could be resolved, this report analyzed the basis behind each proposed approach and determined their individual effectiveness. What was revealed was that since expansive urban and industrial development often places considerable stress on local ecological systems resulting in an altered biotic environment, what is needed is to create a solution that prevents this alteration from taking place or implementing a means of preventing it from getting worse.

This conclusion differs from the approach that was advocated for in the section involving tree planting since that particular method resolves a problem that has already reached its peak rather than preventing it from reaching that point in the first place. The investigation of this report showed that many of today’s flood prevent practices that are used in conjunction wth stormwater runoffs makes rivers unsuitable for particular types of flora and fauna to exist within it.

Rivers and streams that straddle levees located near cities and industrial development areas are considered to be particularly vulnerable given their closer proximity to pollutants and other agents of change. The problem lies in the increased water speed that levees create, the resulting deterioration of beneficial vegetation within the stream, and the sheer amount of water that is forced into the streams/rivers via storm drains. Rivers and streams simply cannot cope with the runoff of an entire city being added within a short period.

The investigated solutions ranging from creating artificial floodplains, planting trees, creating artificial waterways, removing levees and even building extensive underground concrete tunnels were all shown to be effective in various ways. However, further examination of these methods showed that their design is inherently based on flood protection and not environmental preservation. This is why, despite the potential they have for helping to lessen the impact of stormwater runoffs, they are still “lacking” to speak. Further examination of current methodologies surrounding floodplain management and levee construction and maintenance all showcase the same issue of a lack of sufficient consideration regarding the ecology of the river.    While it is true that there have been methodologies that  advocated for preventing the river from being polluted or attempted to preserve the morphology of the river, none of the proposed designs actively sought to protect its ecology. Instead of being an intentional aspect of its design, it seemed to be more of an afterthought. It was based on this that this study developed the conclusion that what is needed is the creation of new design elements that explicitly take into consideration the ecological impact of stormwater runoffs into the river. The first step in doing so was the creation of various blended solutions using some of the strategies that were proposed in this paper. While each proposed design does come with its own issues, it is at least a step forward in floodplain management and levee design that focuses on ecology first, flood control second.

The plans that were developed focused on mitigating the chemical, temperature and sudden influx of water into a river or stream by having it gradually filter through a floodplain before being released into the river. While not necessarily a unique solution, since it was used in Scottsdale and other cities, it is a step in the right direction towards developing an environmentally oriented method of resolving the problem. In fact, the proposed solution in this report takes the Scottsdale methodology even further by suggesting the use of trees and other flora to accept the excess water as well as adding in a system into levees to help distribute the water in a slower manner into the river. The proposed blended solutions contribute to accomplish the objectives of this report by resolving the issue surrounding altered channel morphology, sustaining the biotic richness of the river/stream and preserving the capacity for current runoff systems to continue to operate to prevent flooding.

Overall, this report has contributed to the present-day literature on the issue of stormwater runoffs by identifying their impact on river ecologies, showing what methods are currently in place to help mitigate it, why such methods are insufficient and what can be done to resolve the problem in the future. Moving forward, it should be noted that the proposed solutions in the discussion section of this report are not “perfect” since they also have issues regarding their potential feasibility, the cost of their implementation and the fact that some areas cannot accommodate them.

In the end, the problem stems from overdevelopment with towns and cities being placed in areas that are prone to flooding and the removal of floodplains that were supposed to resolve such issues. If urban and sub-urban development practices can eschew development on floodplains and choose areas that are located farther away from the river, this would go a long way towards resolving the identified issues in this report. Unfortunately, this is unlikely to occur given the current development trends within the country and, as such, engineers would need to develop new ways of dealing with water transfer issues that could have been resolved just by moving to a different location or having a better city and suburb planning process in place.

Recommendation

It is the recommendation of this report that future studies examining the same issue should consider why biodiversity is not at the forefront of a designer’s mind when it comes to designing levees to protect areas that are prone to flooding or implementing an ecologically supportive system to deal with a city’s stormwater runoff. Implementing biodiversity into such designs should be a requirement due to the long-term ecological damage that this lack of foresight could cause to the surrounding area.

This study showed that present-day stormwater runoff designs are often utilized in conjunction with levee construction to quickly shift water away from a city’s streets and onto areas that can handle the flow. However, the design philosophy focuses on moving water rather than taking into consideration what the potential long-term effects be on the river. Is this a lack of foresight on the part of planners or is it due to the current process of education for water displacement engineers wherein the school fails to delve into the subject of ecological awareness? The problem is not something that is isolated to a particular country or system of education; rather, it is endemic in various countries as shown in this paper.

The problem could be an industry-wide lack of Corporate Social Responsibility (CSR) where the focus is on just getting the job done rather than consider the potential harm it could cause to the ecology of a river. The contribution of such an investigation is that it would help to clarify why particular design elements for transferring water have been developed and why new ecologically sound methodologies have been slow to receive widespread acceptance in the industry. Through such an analysis, there is the potential for implementing industry-wide changes to potential place ecologically sound practices at the forefront of an engineer’s mind.

 

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