Earl V. Edris

Fabric reinforced embankment test section, plaquemine Parish, Louisiana, USA

Abstract This paper describes the results of an instrumented high strength woven geotextile fabric reinforced levee test section that was designed and constructed utilizing some of the latest procedures practiced by the US Army Corps of Engineers. The levee test section was instrumented with settlement plates, slope inclinometers, and piezometers. Resistive potentiometers and strain gages were attached to the embedded fabric. The purpose of the test section was to determine the technical feasibility, construction practicality, and the economic feasibility of geotextile reinforced levees for future projects in the Corps of Engineers New Orleans District involving very soft, highly compressible foundations. The strains and loads measured on the fabric were within the range of values estimated during design. The first six months of the test sections performance has been successful. From the test section results, it is anticipated that significant cost savings will be realized when reinforced levees are utilized.

An Integrated Media, Integrated Processes Watershed Model – WASH123D: Part 1 – Model Descriptions and Features

Parametric-based, lumped watershed models have been widely employed for integrated surface and groundwater modeling to calculate surface runoff and pollution loads on various temporal and spatial scales of hydrologic regimes. Physics-based, process- level, distributed models that have the design capability to cover multimedia and multi-processes and are applicable to various scales have been practically nonexistent until recently. It has long been recognized that only such models have the potential to further the understanding of the fundamental biological, chemical, and physical factors that take place in nature hydrologic regimes; to give mechanistic predictions; and most importantly to be able to couple and interact with weather/climate models. However, there are severe limitations with these models that inhibit their use. These are, among other things, the ad hoc approaches of coupling between various media, the simplistic approaches of modeling water quality, and the excessive demand of computational time. This paper presents the development of an integrated media (river/stream networks, overland regime, and subsurface media), integrated processes (fluid flows and thermal, salinity, sediment, and water quality transport) watershed model to address these issues. Rigorous coupling strategies are described for interactions among overland regime, rivers/streams/canals networks, and subsurface media. Generalized paradigms of reaction-based water quality modeling are presented. The cultivation of innovative, numerical algorithms and the implementation of high performance computing to increase the computational speed are discussed. Various application-dependent numerical-options to simulate scalar transport are provided. The necessities to include various options in modeling surface runoff and river hydraulics are emphasized. Several examples are used to demonstrate the flexibility and efficiency of the model as applied to regional-level large scale and project-level small scale problems.

Using the Parallel WASH123D Code to Simulate Overland-Subsurface Interactions

WASH123D model is a first-principle, physics-based model, where water flow and/or contaminant and sediment transport within a watershed system are computed. In the WASH123D model, a watershed is conceptualized as a coupled system of 1-D canal /stream network, 2-D overland regime, and 3-D subsurface media. It is designed to answer the environmental issues concerning both water quantity and quality. To reach numerical solutions with reasonable and tolerable computer time for a regional scale watershed simulation, numerical algorithm improvement and code parallelization are two essential tasks when a distributed numerical model, WASH123D, is used. This paper presents the code parallelization approach, followe d by demonstrating its scalability performance. The test problem of a large mesh uses the topographic data in the C -111 Spreader Canal Project. Background The C-111 Spreader Canal Project is one component of the more than 60 restoration plans under the Comprehensive Environmental Restoration Plan (CERP) and has a goal to provide water deliveries that will enhance the connection between the natural areas in the Southern Glades and Model Lands area of South Dade County. The spreader canal

Using WASH123D to Design Spreader Canals for Water Management in Watersheds

In the federally approved Comprehensive Everglades Restoration Plan (CERP, http://www.evergladesplan.org/), the restoration of the South Florida ecosystem is a major task for the U.S. Army Corps of Engineers and the South Florida Water Management District. Many competing entities have an interest in the restoration process which will probably include physical changes to the land surface and adjustments to water deliveries. The Biscayne Bay Coastal Wetlands (BBCW) Project is one component of more than 60 restoration plans and has a goal to restore or enhance freshwater wetlands, tidal wetlands, and near shore bay habitat. In an effort to restore wetlands, several structures, and management plans and scenarios are considered. One of the plans is to deliver fresh water from the existing canals through a shallow spreader canal system that is to distribute fresh water through wetlands into the Biscayne Bay. To achieve this, a tool is needed to design this complicated shallow spreader canal system. This paper presents how a spreader canal system, which includes 1D canal network routing, 2D overland flow, 3D subsurface flow, and flow through the interface of any two sub domains of the spreader canal system, is simulated with the WASH123D computer code. A brief description of the model will be given. A hypothetical example that includes two cases and uses topographic data and a high -resolution computational mesh for one project area will be considered to demonstrate how WASH123D can help design a spreader canal system. A couple of issues concerning run time and numerical convergence of the coupled flow model will also be discussed in this paper. Background The Biscayne Bay Coastal Wetlands (BBCW) Project is one component of the more than 60 restoration plans and has a goal to restore the coastal wetlands area in Central and South Biscayne Bay along its western shoreline. In the existing condition, fresh water

Modeling Surface and Subsurface Hydrologic Interactions in the Biscayne Bay Coastal Wetlands

Restoration of the South Florida ecosystem is a major undertaking for the U.S. Army Corps of Engineers and the South Florida Water Management District in the federally approved Comprehensive Environmental Restoration Plan (CERP). Many competing entities have an interest in the restoration process which will probably include physical changes to the land surface and adjustments to water deliveries. Restoration plans will be developed using numerical hydrologic models that optimize the benefits among the various stakeholders. Since the health of the South Florida ecosystem is impacted by subtle exchanges of surface and subsurface water, there is a need for great accuracy in the models that will identify the best restoration plans. The accuracy needed for design level simulations of the various projects approaches +/0.1 ft in the water elevations. Models with insufficient physical processes and/or highly schematized models with large grid or mesh induced error will not be sufficient to make design level simulation of South Florida hydrologic processes. Additionally, since a large number of models will be set up and analyzed, effective and efficient graphical user interfaces are needed for the models. This paper presents the results of testing WASH123D code to simulate surface water and subsurface interactions in the groundwater system.

Investigating The Application of Channel Boundary Conditions for Model Calibration and Validation

This study investigated how the stage-type and the flow-type boundary conditions may impact the channel flow solutions in order to address issues concerning adequate channel boundary conditions for model calibration and validation. It is revealed that using the stage-type boundary condition and using the flow-type boundary condition yield the same results as long as the conditions are consistent. Because flow may be more sensitive to the change of system input (e.g., boundary condition, source/sink, model parameter, etc.) than stage (or depth), it is suggested that the more accurate measured stage data be used for calibration with the less accurate measured flow data employed as a secondary check point to ensure correct calibration-validation outcomes. A sensitivity analysis to determine an adequate time-step size for the desired computational mesh is essential for valid model calibration and validation.