Understand How the River Works...Before You Begin Work

Those of us who work with rivers and natural ecosystems need to approach our work carefully, with a measure of ignorance, remembering that rivers are complex. We must come with a clear set of objectives, and seek to understand how the river is working before we can begin our work. I’ve read many books and journal articles but Luna Leopold’s A View of the River ( http://www.amazon.com/View-River-Luna-B-Leopold/dp/0674018451 ) has been most helpful. Leopold theorizes that the river system has two tendencies: to minimize total work done in the system, and to equalize the power per unit bed area. He ties these tendencies back to entropy as used in the second law of thermodynamics, indicating that as energy becomes more evenly dispersed in the river system that the possibility for energy to be used for mechanical work is decreased, thus increasing entropy.

The river system, with both its natural and man-made obstructions, and its sediment load are significant aspects that play into the dynamic equilibrium of the river as expressed in Lane’s relationship.

Qs ds ∝ Qw So

Lane theorized that the product of sediment discharge (Qs) and sediment size (ds) is proportional to the product of river discharge (Qw) and channel slope (So). The side by side photos of a riverbank restoration project are a story in how rivers respond to changes to these variables.

The photo on the left shows an area of significant bank erosion between the downstream end of an earlier bank restoration project and the upstream side of a bridge from which the photo is taken. The missing piece of information is that the former single span truss bridge was replaced with a two span deck girder bridge at about the same time as the first riverbank restoration project was constructed. I have never been a fan of two span bridges over water because the center pier ends up as an obstruction located in the highest velocity portion of the river causing a rise in backwater from losses caused by the pier, and bank instabilities caused by changes in sediment carrying capacity. In this case, during larger floods, the pier presented a greater obstruction, raising the water surface upstream of the bridge, reducing channel velocity, and depositing sediment that created a center bar. The center bar became armored with cobbles, causing flow to become divided and directing the flow to the unprotected bank, downstream of the first riverbank restoration project, which contained finer particle soils. Scour at the toe of the bank resulted in a translational failure of the upper bank. The restoration, shown in the photo on the right, included removing the center bar and extending the bank protection (riprap to the 2-year flood level and dormant live stakes on the upper slope) to the bridge’s abutment.

As this example shows, understanding how the river system works on both a macroscopic and within the river reach being considered is essential before beginning our work.

Finding Sensible Solutions When Values Compete

This photo illustrates the challenge of restoring a riverbank in a place where historic and recreational resources abound and are equally important. At this location along the Cuyahoga River (flowing away from the observer) has a large meander that is naturally migrating downstream and towards the Ohio and Erie Canal towpath shown on the right side of the photo. This reach of river was legislated into the National Park System as a National Recreation Area before later becoming a National Park. Its stated purposes included “…..preserving and protecting for public use and enjoyment the historic, scenic, natural, and recreational values of the Cuyahoga River and adjacent lands in the Cuyahoga Valley, and for the purpose of providing for the maintenance of needed recreational open space necessary to the urban environment”.

Historic resources in the park that also serve as recreational facilities include the Ohio and Erie Canal (including the towpath), the Valley Railway, and a number of houses and bridges. Many of these are on the National Register of Historic Places, and a portion of the Ohio and Erie Canal National Heritage Corridor, runs through the area. Natural resources include the river and a number of ecosystems with associated flora and fauna located in the river and in the river valley, as well as the rural countryside. As to recreational value, Cuyahoga Valley National Park is the 10th most visited park in the National Park system.

The problem to be solved at this and other locations in the park is to protect and preserve a park resource from the advance of the river or tributary using natural materials (rock riprap and vegetation). At this location, because the towpath was still no closer than about 30 feet from the top of riverbank and because the precise location of the future impingement could only be guessed, the solution was to construct several hundred feet of buried rock riprap windrow with a volume of little greater than one cubic yard per running foot. Windrows are designed to “launch” when a meander progresses enough to expose the buried rock, and once launched, to provide a thick enough sloping layer of riprap with large enough riprap to adequately protect the feature. A drainage fabric separated the top of riprap from the backfilled native soils, and dormant willow poles were planted along one side of the excavation to establish some native, deeper rooting vegetation.

One could allow the naturally meandering river to run wild (Cuyahoga means “crooked” river), thereby maximizing ecological values at the expense of threatening the historic and recreational values. On the other extreme, one could design a highly engineered system of concrete or sheetpile protective system to ensure that the river would advance no closer to the towpath trail. In this setting, neither extreme, both of which represent a zero sum game approach, offers a sensible solution. Rather all the values for which this park was created are balanced to provide a minimally invasive ecological solution that provides reasonable assurance that the resource will be preserved and that the public will be able to enjoy it.

Lessons Learned in Restoring Natural Ecosystems - Introduction



There’s been a significant effort by professionals in the fields of water resources/environmental engineering and aquatic biology to restore small and large degraded ecosystems whether they are located in coastal wetlands, freshwater wetlands, estuaries, rivers or streams. These systems are sometimes associated with an environmental permit for new project, but can also be associated with an existing feature that may be threatened by a natural system. For 10 years, I had the pleasure of working as our company’s lead person for projects at Cuyahoga Valley National Park. Many of those projects involved the protection of man-made cultural, historic and recreational features from erosion and flooding from nearby streams and rivers. The photo above shows Yellow Creek (flowing towards the foreground) just upstream of its confluence with the Cuyahoga River where the creek crosses under the Cuyahoga Valley Scenic Railroad. There’s a large bend (meander) in the stream at this location. The proximity of the creek to the railroad has threatened the stability of the railroad embankment on the right side of the photo. As part of this restoration, quarried rock riprap was placed along the railroad embankment to about the level of a 2-yr flood, and then extended away from the railroad as a low rock berm that separates the bank of the stream from the floodplain behind it where wetland trees, shrubs and grasses were planted. Natural vegetation was also placed on the railroad embankment above the top of the rock riprap. As a result, the natural effects of the stream meandering are arrested for the sake of preserving the cultural, historic and recreational resource. I led the planning, design, and construction oversight of a dozen projects similar to this one in the 23 mile Cuyahoga River corridor that comprises this National Park.

These projects provided me with valuable lessons in ecosystem restoration. The lessons helped these projects to be successful in meeting their intended objectives, and are universal in nature. I’ll elaborate more in subsequent blogs on these following lessons:

• Balancing cultural/historic/recreational values with ecological values.
• Understanding how rivers work.
• The importance of engineering in ecosystem restoration.
• The benefits of using of natural and native materials.
• The limitations of human efforts in the good work of restoration.

Serving in the Communion Service

One of the monthly events I most look forward to is the Parkminster Communion service, which happens on the first Sunday of every month. Sometimes I participate like all the congregants, and other times I get to serve by anointing with oil those who choose to be. This past Sunday I received an email sometime on Saturday to serve and I responded immediately with a “yes”.

I take on the role of an anointer feeling both the joy of being together with other believers, and feeling compassion for them. As they walk towards me after receiving the bread and cup, I try to remember their name. When they stop in front of me I speak their name before I begin to pray for them, while making the sign of the cross on their forehead with the oil from a tiny jar. While I typically don’t know their concerns, I know the God who loves them and I know He desires them to be healed. It might be a young married woman who desires a child, a teenager who’s struggling with their sexual identity, an adult dealing with physical pain or a discouraging doctor’s report. I often pray for the men I anoint that God would empower them to be the men that he has called them to be, filling them courage to be bold for Him.

Now and then I get to anoint those in my family, and especially Corinne. This Sunday, nine days after major surgery, I discerned that I should pray that God would continue to hear her far beyond what she could expect or imagine. I prayed that He would give her a bigger healing than she could ever expect.

In so many of the Bible stories, Jesus takes an event and makes it into much more. He takes the funeral of Lazarus and makes it into a resurrection. He creates a feast with extra food to spare for a weary, hungry crowd from 5 loaves and 2 fishes. He takes a wedding that’s short on wine and treats its participants to a finest of wines. In the same way, I want to believe, for each one that comes forward, that God desires a healing, an experience, a life that’s full of abundance, beyond their wildest dreams. That’s why don’t turn down the opportunity to serve His people through the communion service.