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Satellite measurements of lake surface temperature can benefit several environmental applications such as estimation of lake evaporation, predictions of lake overturning, and meteorological forecasts. Using a one-dimensional lake simulation that incorporates satellite measurements of lake surface temperature, the average diurnal variation in lake surface temperature was obtained. The satellite measurements were obtained from the MODIS instrument aboard the Aqua and Terra satellites. Herein the functional form for the diurnal variation in surface temperature is presented for each of the five major lakes in the Savannah River Basin, which are located in South Carolina and Georgia: Lakes Jocassee, Keowee, Hartwell, Russell, and Thurmond. Differences in the diurnal variation in surface temperature between each of these lakes are identified and potential explanations for these differences are presented.

Quantifying evaporative loss from reservoirs plays a critical role in sound water-availability management plans and in reservoir management. Various methods are used to quantify reservoir evaporation; however, each method carries a degree of uncertainty that propagates to model predictions of available water within a reservoir or a reservoir network. Herein, we explore the impact of uncertainty in reservoir evaporation on model outputs of historical and future water availability throughout the five major reservoirs in the Savannah River Basin in South Carolina, USA, using four different evaporation methods. Variability in the total available water is evaluated using the United States Army Corps of Engineers (USACE) 2006 Drought Contingency Plan hydrologic model of the Savannah River Basin, which incorporates recent water-management plans and reservoir controls. Results indicate that, during droughts, reservoir evaporation plays a large role in water-availability predictions, and uncertainty in evaporative losses produces significant uncertainty in modeled water availability for extreme events. For example, the return period for an event in which the availability of water in Lake Hartwell was reduced to 50% of full pool capacity varied from 38.2 years to 53.4 years, depending on the choice of evaporation parameterization. This is a variation of 40% in the return period, depending on the choice of evaporation method.

We assessed the effectiveness of an integrated engineering public-speaking class relative to a traditionally taught public-speaking class. The integrated class was designed to meet the grow...

The flight of compact debris can be highly stochastic in nature. However, standard flight equations are deterministic after assuming a spherical shape for gravel. This study proposes a stochastic model to resolve some key aspects of these uncertainties that originate due to changes in orientation of the debris particle during flight. The model numerically solves the differential equations of motion for a large number of gravel pieces taken from five different size gradations. The amount by which the drag and lift coefficients ( δ C D and δ C L ), the lift force direction ( δ θ ) and the projected area ( δ α ) are varied at each time-step during the flight simulation of a single debris are the four parameters used to fit the model to the results obtained from gravel drop experiments. An optimization criterion ( e ) was introduced and the model was optimized for each gravel gradation tested. It was found that only small perturbations in the lift coefficient are needed to model the flight. However, larger perturbations in the direction of the lift force are required to correctly predict the statistics of the landing locations.

To date, due to difficulties in making measurements during wildfires, much of what is known about firebrand showers and the subsequent fire spotting comes from mathematical modeling of the lofting and downwind transport of firebrands. However, these models lack experimental validation. Hence, the coupled lofting and downwind transport of non-combusting rod-like firebrands is experimentally modeled by releasing them through the velocity field of a large scale boundary layer wind tunnel. Complete trajectories of model firebrands are resolved using image processing algorithms. The results show a strong positive correlation between the maximum rise height (zmax) and the landing location (xl) of model firebrands. In addition, it is shown that, given the velocity field, the empirical probability density functions (PDF) of x l / z max are similar regardless of the firebrands' aspect ratio. This implies that the lofting and downwind transport processes cannot be decoupled in transport models. Analysis of the data reveals that, the larger the aspect ratio of firebrands, the more sensitive their landing locations are to the variability in the velocity field through which they are released. The data set presented herein serves as the most comprehensive experimental evidence for not only firebrand transport studies but also for validating mathematical models for the flight of rod-like debris/brands within the velocity field of other extreme events such as hurricanes.

Satellite measurements of water surface temperature can benefit several environmental applications such as predictions of lake evaporation, meteorological forecasts, and predictions of lake overturning events, among others. Limitations on the temporal resolution of satellite measurements can restrict these improvements. A model of the diurnal variation in lake surface temperature could potentially increase the effective temporal resolution of satellite measurements of surface temperature, thereby enhancing the utility of these measurements in the above applications. As a step in this direction, herein a one-dimensional thermal model of a lake is used in combination with surface temperature measurements from the moderate resolution imaging spectroradiometer instrument aboard the Aqua and Terra satellites, along with ambient atmospheric conditions from local weather stations, to calculate the diurnal surface temperature variation for Lake Hartwell in South Carolina. The calculated solutions are used to obtain a functional form for the diurnal surface temperature variation of this lake, a result which has not been obtained heretofore. This functional form was obtained by averaging over several years worth of data and, therefore, represents the diurnal variation of surface temperature of the average day. Accordingly, attempts to use this averaged function to predict surface temperature in between satellite overpasses on any given day did not perform well due to day-to-day variations in cloud cover, wind speed, and other factors. It is possible that use of this averaged function combined with daily meteorological data may enable better performance.

Highly buoyant plumes, such as wildfire plumes, in low to moderate wind speeds have initial trajectories that are steeper than many industrial waste plumes. They will rise further into the atmosphere before bending significantly. In such cases the plume's trajectory will be influenced by the vertical variation in horizontal velocity of the atmospheric boundary layer. This paper examined the behavior of a plume in an unstratified environment with a power-law ambient velocity profile. Examination of previously published experimental measurements of plume trajectory show that inclusion of the boundary layer velocity profile in the plume model often provides better predictions of the plume trajectory compared to algebraic expressions developed for uniform flow plumes. However, there are many cases in which uniform velocity profile algebraic expressions are as good as boundary layer models. It is shown that it is only important to model the role of the atmospheric boundary layer velocity profile in cases where either the momentum length (square root of source momentum flux divided by the reference wind speed) or buoyancy length (buoyancy flux divided by the reference wind speed cubed) is significantly greater than the plume release height within the boundary layer. This criteria is rarely met with industrial waste plumes, but it is important in modeling wildfire plumes.

A warming climate leads to a moister atmosphere and more rapid hydrologic cycle. As such, many parts of the country are predicted to experience more total rainfall per year and more frequent extreme rainfall events. Most regions of the country have stormwater systems designed to a standard that matches outflow rates to pre-development values for specified return period storms. Increases in these return period storm depths, as predicted by many global climate models, will stress existing stormwater infrastructure. This paper examines how rainfall patterns will change over the remainder of the century across the state of South Carolina. Rainfall simulations from 134 realizations of 21 global climate models were analyzed across the state of South Carolina through 2099. Results show that there will be increases in both annual total rainfall (ATR) and 24-hour design storm depth for a range of return period storms. Across South Carolina, ATR is predicted to increase by approximately 2.3-4.0 inches over the forecast period while the 100 year design storm depth is predicted to increase by 0.5-1.2 inches depending on location. However there are significant regional variations with the Savannah River Basin experiencing smaller increases in ATR compared to the rest of the state.

This technical note outlines an initial assessment of the feasibility of using water sprays to intercept and extinguish airborne embers, as a means to protect buildings during wildfires. An analytical model was developed to calculate the probability of inter-particle collisions within two intersecting streams of particles, and was then applied to a range of test cases involving embers and water droplets. Results from this simplified analysis indicated that water sprays could effectively protect buildings from ‘ember attack’ in this manner, but only when either: i) large water flow rates were used (in the order of 1 L s−1 per metre of building perimeter to be protected), or ii) the sprays were comprised of very small (~0.1 mm) droplets at moderate water flow rates (~0.1 L s−1 m−1). It is likely that the quantity of water required to satisfy (i) would not be available in many circumstances, and further investigation is required to determine whether sprays of ~0.1 mm droplets could operate effectively in the conditions of a wildfire. The analysis presented herein would be a suitable basis for further investigation into these spray systems, and for quantitative comparison with other types of wildfire sprinkler systems.

The purpose of this study was to determine how a real-world, sustainability-focused engineering capstone course affected students' critical thinking skills, student knowledge of sustainability, and student and faculty workloads. The research also investigated the effectiveness of a classwide jigsaw team approach. A combination of qualitative and quantitative assessment tools, including surveys, journals, interviews, and timecards, was employed to investigate the research questions. Results revealed that a real-world project with a focus on sustainability positively impacted students' critical thinking skills and led to increased knowledge of sustainability, but it also correlated with a high workload for students and faculty. Additionally, the jigsaw organization structure proved successful and yielded a positive team- building experience for the students. These results suggest open-ended problems with real project constraints can yield a uniquely beneficial learning experience without sacrificing the quality of student design or project deliverables. DOI: 10.1061/(ASCE)EI.1943-5541.0000141. © 2013 American Society of Civil Engineers. CE Database subject headings: Sustainable development; Students; Engineering education; Undergraduate study. Author keywords: Capstone; Sustainability; Real-world project; Critical thinking; Integrative thinking; Student workload; Faculty workload; Jigsaw team; Community-based project; Undergraduate engineering education.

This study investigated methods for predicting and managing surface water spread and depth on porous pavement bike lanes adjacent to impervious traffic lanes. Results are presented from a t...

Experimental results are presented for the shear-driven flushing of a dense fluid from a square street canyon. The flow is both qualitatively and quantitatively influenced by the density of the fluid in the canyon, which is parameterized in terms of the flow Richardson number. A total of 26 experiments were conducted for Richardson numbers ranging from 0.08 to 4.5. For low Richardson numbers the canyon remains well mixed during the flushing process and the density difference decays exponentially (as observed in previous studies flushing a neutrally buoyant tracer). As the Richardson number increases the canyon becomes more stably stratified and the decay rate reduces. For very high Richardson numbers, a two-layer stratification is observed. Over time, for the two-layer case, the lower dense layer gets thinner, indicating that dense fluid is being skimmed from the top of the layer, and less dense, indicating that ambient fluid is being mixed down into the dense layer. Previous studies only observed flushing by skimming. The layer buoyancy decreases linearly over time until the shear layer reaches the bottom of the canyon at which point the rate of layer buoyancy reduction dramatically increases. Results also indicate that the density interface is thinner than the shear layer that is driving the mixing, and that the difference in thicknesses increases with an increasing Richardson number. This result is consistent with previous studies of mixing in stratified shear flows. The initial exponential decay rate was calculated for each experiment and is given by k = 1 / ( 18 + 84 R i ) 1.21 . Following the initial period of exponential decay, the decay rate increases as the stratification weakens.

In this study the discharge coefficient for circular orifices of different size in two different sizes of riser pipe is investigated experimentally. This type of outlet structure is common in detention ponds to achieve runoff volume control from developed areas in order to meet outflow discharge and water quality requirements. The discharge coefficient is determined by recording the drop in pond water level with time as water flows out of the orifice. The discharge coefficient is found to be a function of head over the orifice, location of the orifice above the floor of the tank, and the ratio of the orifice diameter to riser pipe diameter. The discharge coefficient increases as the head over the orifice decreases and height of the orifice above the floor of the tank decreases. The discharge coefficient reduces as the ratio of the orifice diameter to pipe diameter increases and eventually reaches an asymptotic value. Also, with all other variables being the same, the discharge coefficient is lower for larger size riser pipe. An equation that is a function of head over the orifice and height of the orifice above the floor of the tank is fitted for each ratio of orifice diameter to piper diameter. The coefficients of the equation are found to be a function of the ratio of orifice diameter to piper diameter. A minimum coefficient of determination of 0.78 for the fitted equation suggests that the fit can be used to determine the discharge coefficient for orifices in circular riser pipes.

We examine the role of diffusivity, whether molecular or turbulent, on the steady-state stratification in a ventilated filling box. The buoyancy-driven displacement ventilation model of Linden et al. (J. Fluid Mech., vol. 212, 1990, p. 309) predicts the formation of a two-layer stratification when a single plume is introduced into an enclosure with vents at the top and bottom. The model assumes that diffusion plays no role in the development of the ambient buoyancy stratification: diffusion is a slow process and the entrainment of ambient fluid into the plume from the diffuse interface will act to thin the interface resulting in a near discontinuity of density between the upper and lower layers. This prediction has been corroborated by small-scale salt bath experiments; however, full-scale measurements in ventilated rooms and complementary numerical simulations suggest an interface that is not sharp but rather smeared out over a finite thickness. For a given plume buoyancy flux, as the cross-sectional area of the enclosure increases the volume of fluid that must be entrained by the plume to maintain a sharp interface also increases. Therefore the balance between the diffusive thickening of the interface and plume-driven thinning favours a thicker interface. Conversely, the interface thickness decreases with increasing source buoyancy flux, although the dependence is relatively weak. Our analysis presents two models for predicting the interface thickness as a function of the enclosure height, base area, composite vent area, plume buoyancy flux and buoyancy diffusivity. Model results are compared with interface thickness measurements based on previously reported data. Positive qualitative and quantitative agreement is observed.

Numerical simulations were conducted to model the transient flow development in a naturally ventilated space containing a centrally located localized source of heat. The simulations were compared with a series of small-scale laboratory experiments and existing theoretical models. The aim of the work was to benchmark CFD models for time-dependent buoyancy-driven natural ventilation against previously published experimental results and theoretical models. The simulations agree well with experimental results during the initial development of the room stratification. The CFD results accurately predict the maximum depth of the hot buoyant layer at the top of the room as well as the steady-state interface height which separates the warm upper buoyant layer from the cooler air below. The simulations also predict well the time taken for the buoyant upper layer to reach its maximum depth. However, at longer times the results diverge. This may be due to thermal diffusion and mixing at the interface between the upper and lower layers due to the inflow from the floor level vents.

The interaction of turbulent plumes is examined in the context of building ventilation flows. Recent models for natural ventilation have been based on simplified treatment of the heat sources in a ...

Results are presented from an experimental study of the stage discharge relationship for a porous pipe buried under loose laid aggregate. A series of steady-state experiments were performed in which the depth of flow over the pipe was measured for a given pipe discharge. The stage-discharge relationship for the entire system is well described by an orifice equation when the water surface in the aggregate trench was horizontal and the pipe was running full at the outlet. An energy equation analysis shows that the dominant energy losses are due to flow through the small side wall orifices into the pipe and from friction losses along the pipe. Friction losses in the aggregate are shown to be negligible, which again supports the orifice equation model. Discharge coefficients are reported for three commonly available porous pipes. The results of this research can be used in the sizing and placement of subsurface drains in aggregate filled storm water infiltration practices such as infiltration trenches...