How Do You Design a Stream?

SUMMER 2010

BY: Aziza Baan, John Kiefer, PhD, PE, PWS, Kristen Blanton, MS & Karen Warner, MS

Aziza Baan

In the Florida phosphate mining region, reclamation of stream channels is rigorously regulated at the state and local level with requirements to maintain or improve the biological functions of these systems affected by surface mining operations (Florida Statutes (FS), Chapter 378). AMEC-BCI has worked closely with mining clients and the Florida Institute of Phosphate Research, (FIPR) to develop design metrics for restoration and reclamation of first order streams in Florida. Stream creation techniques have evolved from allowing channels to self-adjust via natural weathering processes to carefully constructing the riparian system mechanically. CF Industries (CF) hired AMEC-BCI to assist in piloting a state-of-the-art demonstration project of natural channel design. The Doe Branch-5 (DB-5) project provided an opportunity to add a construction technique that differs from those deployed at previously successful stream creation projects such as DB-2 which involved stream creation by hydraulic carving. The objective was to create a palmetto lined stream that could be designed and constructed cost effectively in a few months.

How Do You Build a Stream?

SUMMER 2010

BY: Karen Warner, MS, Mike Channen, PE, John Kiefer PhD, PE, PWS, Kristen Blanton, MS, Aziza Baan & Jacqueline Levine

Karen N. Warner, MS

Despite best efforts to avoid and minimize impacts to natural streams wherever possible, impacts sometimes occur on natural systems, and more often to altered stream channels degraded through historic land use practices. Starting in 2004, phosphate miners became the first regulated sector in Florida required to explicitly mitigate stream impacts with in-kind stream channel replacements (per 62C-16 Florida Administrative Code). Prior to this requirement, the need for stream restoration and/or reclamation to replace lost habitat had been approached through various methods with equally varying levels of success over many decades. Stream construction techniques of the past and present include reliance upon self-adjustment under climatic influences, mechanical construction, or in most cases, a combination of these techniques. The phosphate industry’s experience with these three construction techniques provides valuable lessons for stream restoration in any rural Florida setting. This body of knowledge will soon become increasingly valuable because the US Army Corps of Engineers is currently working on new in-kind stream mitigation guidance for all applicants across the state.

How Do You Assess a Stream?

SUMMER 2010

Jacqueline Levine

How we assess a stream depends primarily upon what type of biometrics we want to measure. In order to ensure complete data coverage, any number of analysis styles and types may be applied. Our Stream Team’s extensive expertise ensures that the successful solution will be found to help our design teams create a plan to preserve and/or restore biological integrity to our clients’ systems.

Choosing the appropriate assessment or assessments may also depend on the type of stream you will be working in. Our team has a deep understanding of the appropriate stream classification systems and is prepared to create an assessment and monitoring plan to ensure proper functions are restored or maintained.

Interspecific and Interseasonal Differences in Water Depth Distribution and Cover of Dominant SAV in the Lower St. Johns River

SUMMER 2010

Jennifer Sagan

Submerged aquatic vegetation (SAV) colonizes approximately 2140 acres corresponding to the mesohaline/oligohaline and freshwater sections within the Lower St. Johns River (LSJR). Ten species of freshwater and brackish angiosperms as well as charophyte genera were routinely seen along the littoral shelves of the LSJR during field surveys. Ruppia maritima was the only halophyte present within the river. Vallisneria americana, Najas guadalupensis and R. maritima were the dominant species in the system, accounting for 67%, 16% and 8%, respectively, of total SAV cover. The objective of the study was to investigate 1) year-round interspecific maximum water depth distribution and 2) inter-seasonal differences in maximum water depth distribution for each species. In addition, within-bed distribution of these species was obtained. Four years of fall, winter, spring, and summer data were included from fall 2000 through summer 2004 corresponding to periods ranging from drought conditions to above-normal precipitation.

AMEC-BCI’s Nirjhar Shah, PhD, publishes articles on enhancing modeling conceptualization in shallow water table environments

SPRING 2010

Nirjhar Shah, PhD

Project Engineer Dr. Nirjhar Shah recently published two articles that describe and explore the need for improvements to the modeling techniques currently utilized for shallow water-table environments to incorporate the dynamic interaction of the surface and groundwater processes due to shallow water-table conditions. The article entitled “Variability in Specific Yield under Shallow Water-table Conditions” was published in the ASCE Journal of Hydrologic Engineering and the second entitled, “Observations of Long Term Air Entrapment Affecting Runoff and Water-table Fluctuations” was published in the International Journal of Water.

Both of these articles are extensions of Dr. Shah’s dissertation which involves enhancing modeling conceptualization for shallow water-table environments, such as in the South Eastern United States. These articles are intended for people working in the hydrologic and hydraulic modeling field and illustrate that processes such as variability in specific yield and air entrapment have to be studied in greater detail such that their impact can be fully understood.

The articles were born out of a need to revisit the processes that cause or impact water-table fluctuations. This was determined because for shallow water-table environments it becomes very difficult to model the water-table fluctuations using traditional methodologies. Model parameters have to be tweaked sometimes to values which may depart significantly from the widely accepted parameter’s value. The objective was to make sure that the modeling conceptualizations that are used currently are sufficient to describe the physical processes. Dr. Shah has provided summaries of both articles and the results of the findings for this publication.

Publications

How Do You Design a Stream?

How Do You Build a Stream?

How Do You Assess a Stream?

Interspecific and Interseasonal Differences in Water Depth Distribution and Cover of Dominant SAV in the Lower St. Johns River

AMEC-BCI’s Nirjhar Shah, PhD, publishes articles on enhancing modeling conceptualization in shallow water table environments

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