Time filter

Source Type

San Isidro, Peru

Leon A.S.,Oregon State University | Kanashiro E.A.,Ausenco Vector | Valverde R.,Oregon State University | Sridhar V.,Boise State University
Journal of Water Resources Planning and Management | Year: 2014

This paper presents a case study on the application of a dynamic framework for the intelligent control of flooding in the Boise River system in Idaho. This framework couples a robust and numerically efficient hydraulic routing approach with the popular multi-objective nondominated sorting genetic algorithm II (NSGA-II). The novelty of this framework is that it allows for controlled flooding when the conveyance capacity of the river system is exceeded or is about to exceed. Controlled flooding is based on weight factors assigned to each reach of the system, depending on the amount of damage that would occur, should a flood occur. For example, an urban setting would receive a higher weight factor than a rural or agricultural area. The weight factor for a reach does not need to be constant as it can be made a function of the flooding volume (or water stage) in the reach. The optimization algorithm minimizes flood damage by favoring low-weighted floodplain areas (e.g., rural areas) rather than high-weighted areas (e.g., urban areas) for the overbank flows. The proposed framework has the potential to improve water management and use of flood-prone areas in river systems, especially of those systems subjected to frequent flooding. This work is part of a long-term project that aims to develop a reservoir operation model that combines short-term objectives (e.g., flooding) and long-term objectives (e.g., hydropower, irrigation, water supply). The scope of this first paper is limited to the application of the proposed framework to flood control. Results for the Boise River system show a promising outcome in the application of this framework for flood control. © 2014 American Society of Civil Engineers. Source

Breitenbach A.,Ausenco Vector
Geosynthetics | Year: 2011

Allan Breitenbach explains how the underliner soil materials on his projects were typically tested at optimum moisture and 95% of standard compaction in combination with an overliner of clean sand and gravel cover fill. The test re-runs differed by several degrees of friction strength, along with variable apparent cohesion values, using the same test equipment, materials, and procedures. The purpose of the testing was to verify the reliability of the 4-inch direct shear box in determining accurate test strengths. The overliner soil material comprised clean sandy gravel placed in a single loose lift and wetted to simulate a protective drain cover fill above the liner surface. The more flexible PVC liner showed no significant increase in restricted liner strength due to its high elongation characteristics. The other point in the restricted versus unrestricted liner argument is that it is still an apparent common practice in landfills to place composite clayey soils wet of optimum to meet regulatory specified low permeability requirements. Source

The article details the current methods for assessing remaining service life and provides an explanation of why existing ponds may not be performing as predicted. The typical ageing process for HDPE geomembranes involves three stages. In modern meomembranes, the initial OIT value can be around 130 minutes, which represents the time it takes for the geomembrane sample to reach the exothermic peak when held isothermally at 200 C at the given pressure for the test method in an oxygen environment. The length of Stage III can depend on which physical property is measured. Albeit arbitrarily, the service life of the geomembrane is considered to be the sum of the time it takes the geomembrane to complete the three stages. Contaminant transport modeling was used in conjunction with the measured chloride leachate concentrations throughout the clay samples to assess when the geomembrane ceased functioning. Source

Breitenbach A.,Ausenco Vector
Geosynthetics | Year: 2011

Allan J. Breitenbach, P.E. focuses on the factors that influence liner interface test strengths. The friction strength can approach zero degrees with the cohesion intercept at its maximum value for a relatively saturated and fine-grained soil approaching unconsolidated and undrained conditions with quick loading and fast shearing rates. Under these conditions, the apparent cohesion should be discarded for a conservative friction strength estimate or a retest can be conducted with a longer time for pretest load consolidation and dissipation of excess pore pressures. The mining project experience gained from conducting large pilot scale liner test fills using loaded rock haul truck traffic at mine sites, observations of liner drain fill cover and heap lift construction, numerous large-scale direct shear box tests performed at optimum or dry of optimum moisture content, and a review of known pad liner slope failures all point to only one conclusion. Source

Leon A.S.,Oregon State University | Kanashiro E.A.,Ausenco Vector | Gichamo T.Z.,Oregon State University | Valverde R.,Oregon State University | Gifford-Miears C.,Oregon State University
World Environmental and Water Resources Congress 2012: Crossing Boundaries, Proceedings of the 2012 Congress | Year: 2012

This paper presents a new framework for the intelligent control of river flooding. This framework links two components: river system routing (simulation) and optimization. The river system routing component builds upon the application of Performance Graphs (precomputed hydraulics under gradually varied flow scenarios), while the optimization component uses the popular second generation multi-objective evolutionary algorithm Nondominated Sorting Genetic Algorithm-II (NSGA-II). The use of hydraulic performance graphs for river system routing results in a robust and numerically efficient model as most of the computations for the system routing only involves interpolation steps. The proposed framework allows controlled flooding in the event that the capacity of the river system has been exceeded. This controlled flooding is based on weight factors assigned to each reach of the system depending on a hierarchy of risk to losses associated with flooding. Naturally, river reaches that are less prone to flood losses are assigned smaller weight factors and reaches that are more prone to flood losses are assigned larger weight factors. For illustration purposes, the proposed framework was applied to the Boise river system in Idaho. The results show a promising outcome in the application of this model for flood control. © ASCE 2012. Source

Discover hidden collaborations