Modeling Reservoir Density Underflow And Interflow From A Chemical Spill

Abstract

An integral simulation model has been developed for understanding and simulating the process of a density current and the transport of spilled chemicals in a stratified reservoir. The model is capable of describing flow behavior and mixing mechanisms in different flow regimes (plunging flow, underflow, • and interflow). It computes flow rate, velocity, flow thickness, mixing parameterized by entrainment and dilution, depths of plunging, separation and intrusion, and time of travel. The model was applied to the Shasta Reservoir in northern California during the July 1991 Sacramento River chemical spill. The Simulations were used to assist in the emergency response, confirm remediation measures, and guide data collection. Spill data that were available after the emergency response are used to conduct a postaudit of the model results. Predicted flow parameters are presented and compared with observed interflow intrusion depth, travel time, and measured concentrations of spilled chemicals. In the reservoir, temperature difference between incoming river flow and ambient lake water played a dominant role during the processes of flow plunging, separation, and intrusion. With the integral approach, the gross flow behavior can be adequately described and information useful in the analysis of contaminated flow in a reservoir after a spill is provided. concentrations in the river-reservoir stretch results from dilution due to mixing with the ambient water as well as from degradation and volatilization. Since small amounts of degradation and volatilization continued as the spill entered the reservoir, these calculations of mixing and dilution are ex-695 696 GU ET AL.: MODELING RESERVOIR DENSITY UNDERFLOW AND INTERFLOW N Can•ara Loop Spill Site Dunsmuir-Fishing Access (RB) Dunsmuir-Simpson St. (Co)

Effect of thermal stratification on interflow travel time in stratified reservoir

“…Gu et al (1996) and Gu and Chung (1998; used various simulation models (1D integral model, 2D mixing-length model, and code CE-QUAL-W2) to investigate the density current in a thermally stratified environment. They studied the effects of inflow boundary conditions, ambient stratification, and geometry on the behavior of a density current, and found that an inverse relationship exists between ambient stratification and interflow travel time.…”

Two-dimensional simulation of a thermally stratified reservoir with high sediment-laden inflow

“…For the reservoir with shallow water basin the aspect ratio of vertical to horizontal scale is rather small, thus the assumption of hydrostatic pressure equation is proposed and justified by the excessive studies by King (1985a,b). For lakes or reservoirs with small aspect ratio in width/length dimension, a laterally averaged two-dimensional model (Buchak and Edinger, 1982;King, 1985a;Karpik and Raithby, 1990;Gu et al" 1996;Choi, 1998;Chung and Gu, 1998) can be used to study the density currents in the longitudinal-vertical cross section which is vital to the modeling of the hydrothermal structure. If the objective of the study is only limited to determine the vertical temperature profile of the lake/reservoir, where measurements are not avail able, a simple one-dimensional model can be described using the energy equation for the water column (Hondzo and Stefan, 1993).…”

Variation of Inflow Density Currents with Different Flood Magnitude in Daecheong Reservoir

“…연구결과 dp, Xp, ds, Chung and Gu, 1998 (Fischer et al, 1979;Chung and Gu, 1998). 상층류의 형태로 흐르던 유입수는 흐름에 의한 운동량과 음부력 이 같아지는 지점에서 저수지 수면 아래로 침강하게 되 며, 이러한 현상이 일어나는 지점을 침강점이라고 한다 (Fischer et al, 1979;Ford and Johnson, 1981; (Baker and Paulson, 1981), DeGray 호수 (Ford and Johnson, 1981) 그리고 Wellington 저수지 (Hebbert et al, 1979) 등에서 현장실험이 이루어 졌으며, Alavian (1986), Johnson et al (1987Johnson et al ( , 1989 (1) et al(1989) 1.8 -21 > 10,000 Laboratory study Stefan and Johnson(1989) 3.0 -4.0 530,000 Field study, wastewater effluent Gu et al(1996) Table 1에 정리하였다. CE-QUAL-W2 dp(m) dp ( 값이 dp/ho보다 작거나 유사한 값을 보이고 있다.…”