Straight Stream Research Articles

Decisive significance of lineaments on groundwater occurrence in the Khapri watershed of Deccan Volcanic Province (DVP), district Dangs, Western India

This study investigates the influence of geological lineaments on groundwater occurrence in the Khapri watershed, Dangs district, Gujarat, where rugged terrain and less transmissible basaltic rocks limit infiltration despite high rainfall (2000 mm). Lineaments were mapped using IRS LISS-III satellite data and eight hill-shades generated at various azimuth angles (45°, 90°, 135°, 180°, 225°, 270°, 315°, and 360°) from Carto-Digital Elevation Model (DEM) in GIS environment to ensure maximum extraction. These lineaments, validated through Google Earth and ground-truthing, were categorized into positive (ridges, plateaus, dykes) and negative (joints, fractures, straight stream segments) based on their contribution to water infiltration. The comprehensive lineament map revealed dominant NNE-SSW and ENE-WSW orientations. Positive lineaments largely induce runoff, while negative lineaments support water infiltration. The study indicates a moderate correlation between lineament densities and the groundwater regime. Regions with high negative lineament density exhibit lower groundwater fluctuation, indicating better groundwater occurrences, while areas with high positive lineament density show greater fluctuation, indicating lesser groundwater occurrence. Linear regression analysis indicates that 48% and 50% of the variation in groundwater fluctuation is explained by positive and negative lineament density, respectively. This analysis emphasizes the importance of identifying and mapping negative lineaments for targeting groundwater resources in hard rock terrains.

Simulating tectonically controlled fractal landscape evolution in the Three Rivers Region (SE Tibetan Plateau margin)

The long-term development of fluvial landscapes is sensitive to tectonic movement. This is the case for the Three Rivers Region, located on the southeastern margin of the Tibetan Plateau, where it is critical for understanding the continuous collision and compression between the Indian and Eurasian plates. However, quantitative perspectives on this landscape evolution are lacking. Based on present global positioning system (GPS) data, a quantitative expression of two phases of regional deformation, a northeast-southwest shortening and dextral shear deformation, was proposed to represent the continuous Indian-Eurasian collision. By incorporating this tectonic pattern into a landscape evolution model and integrating the regional differential uplift, the numerical results quantitatively present a dynamic shaping of the Nu, Lancang, and Jinsha rivers in the SE Tibetan plateau margin. Analyses of the fractal dimensions of these river networks indicate that two tectonic deformation phases significantly controlled regional landscape development and its unique drainage features. The numerical simulations depict the river networks to comprise very long and relatively straight stream trunks, and relatively small and short tributaries. The tectonic shortening and its accompanying rapid uplift prevented the development and lengthening of the tributaries, which might have promoted the formation of low-relief surfaces. With comparison to the digital elevation model (DEM), the fractal features of the river networks extracted from the numerical results are consistent with those extracted from the natural river networks, despite the simplicity of the numerical model. More broadly, based on the more realistic kinematic scenarios and reasonable constraints, this study contributes to the development of an effective and applicable model that can reveal important implications for the landscape evolution of the region.

Assessment of functional and cosmetic outcomes of Extended-Tubularized incised plate for mid-shaft and distal hypospadias as a modification of Snodgrass repair: a cross-sectional study.

Hypospadias is a congenital abnormality of anterior urethral and penile development where the urethral meatus is ectopically located on the ventral aspect of the penis. It is a relatively common condition affecting ~1 in 250 male birth. Extended-Tubularized Incised Plate (E-TIP) is a modification of Snodgrass repair by extending the midline incision to the apical part of the glans resulting in a more normal appearing location of the meatus and straight urinary stream without increasing the risk of complications. To evaluate functional and cosmetic outcomes of E-TIP repair for mid-shaft and distal hypospadias as a modification of Snodgrass repair. A prospective cross-sectional study including 53 cases of mid-to-distal hypospadias repaired with the E-TIP technique between November 2019 and February 2022 in Baghdad. The authors start with the standard technique described by Snodgrass, but the midline incision of the urethral plate extended up to the apical part of the glans tip, and tabularization started distally creating a slit-like a neomeatus. Outcome assessment depended on an objective evaluation of the following parameters: maximum flow rate, post-void residual, Hypospadias Objective Score Evaluation (HOSE) score, and direction of the urinary stream. The mean age was 3.4±2.1 years, ranging from 0.6 to 9 years. The mean duration of follow-up was 14.4±6.9 months, and the location of the meatus was coronal in 16 patients (30%), subcoronal in 25 (47%), and mid-distal shaft in 12 (23%). The glans width was greater than or equal to 14mm in 46 patients (87%) and less than 14mm in 7 (13%). Q.max was above the fifth percentile of age-related uroflowmetry nomograms for healthy children 5-15 years old in 29 boys (93.5%) and below the fifth percentile in 2 (6.5%). Post-void residual urine was less than 10% of voided volume in 28 out of 31 boys (90%) and greater than 10% in 3 (10%). Regarding cosmetic outcomes, 50 boys (94%) had good penile appearance and their HOSE score greater than or equal to 14 with a slit-like meatus located at the tip of the glans, while 3 (6%) of them their score was less than 14. The overall mean HOSE score postoperatively for all patients was 15±0.9. Six patients (11%) had a deviated urinary stream and 47 (89%) had a straight stream. E-TIP repair is a good alternative to standard Snodgrass repair for mid-shaft to distal hypospadias with a good functional and cosmetic outcome, particularly the neomeatus position at the tip of the glans, which is similar to the normal one without increasing the risk of meatal stenosis.

Hyporheic Exchange in a Straight Stream With Alternate Bars

AbstractHyporheic exchange (HE) is essential to riverine ecosystem, water quality, and energy cycling in a stream due to its governing role in physicochemical and biological processes in hyporheic zone (HZ). Alternate bars, characterized by a repetitive sequence of diagonal bars with a pool‐riffle bedform, are common geomorphic features that generally form in straight streams. Following similar laboratory and numerical methodology as Huang and Chui (2021, https://doi.org/10.1029/2020wr029182) who investigated the HE induced by pool‐riffle sequences, this study focused on the HE induced by alternate bars (i.e., geomorphic features on stream banks instead of streambed) where the influences of key factors were systematically examined. The results show that alternate bars strongly influence surface flow and induce significant hyporheic flows in both stream banks and streambed, whose patterns, magnitudes, and influential patterns of key factors could be similar to the HE induced by pool‐riffle sequences. The HE flowrate increases linearly with discharge, bed slope, and bar spacing. However, influential patterns of bar width on HE vary, and the bar width changes the influential patterns of discharge and bed slope on HZ scale, highlighting the influence of bar width in the complex interactions among discharge, bed slope, and bar width. All indicators of HE characteristics generally increase with bar spacing and follow exponential relationships with groundwater flow. Findings in this study lay the foundation in research on riparian ecosystems and water quality in the streams with alternate bars and help guide the design of bars during river restorations.

Urethral mobilization and advancement technique in distal types of hypospadias: short-term local experience

BackgroundA prospective study was conducted on 65 cases with distal hypospadias operated using the urethral mobilization technique between July 2017 and December 2019. Patients with proximal hypospadias and those with distal hypospadias, but with a hypoplastic urethra, were excluded from the study. In this technique, the urethral tube was mobilized proximally in a ratio of 3–4:1 (the ratio of mobilized urethral length to the initial distance between the native meatus and the tip of the glans) then positioned distally after creating wide glans wings. The aim of this study was to assess the outcome of the urethral mobilization technique in distal hypospadias in our center.ResultsThe age of patients was ranged 9 months to 7 years old (mean 37.5 months); 17 (26%) cases were already circumcised. During the postoperative follow-up, 62 (95.4%) patients had a good caliber neomeatus with a good and straight urinary stream; the remaining 3 (4.6%) cases developed meatal stenosis which responded well to urethral dilatation. One (1.5%) patient had a minor retraction of neomeatus but remained within the glans and not requiring further intervention. Four (6%) cases developed minor hematoma which was resolved on conservative measures. Six (9.2%) patients developed minor wound infection which was treated with daily dressing and antibiotic coverage.ConclusionThe urethral mobilization technique is a good choice for repairing distal hypospadias especially for boys who are previously circumcised as the preputial flap is not required in this technique. It provides good cosmetic and functional results, with a fewer complication rate.

Focusing and splitting streams of soft particles in microflows via viscosity gradients.

Microflows are intensively used for investigating and controlling the dynamics of particles, including soft particles such as biological cells and capsules. A classic result is the tank-treading motion of elliptically deformed soft particles in linear shear flows, which do not migrate across straight streamlines in the bulk. However, soft particles migrate across straight streamlines in Poiseuille flows. In this work we describe a new mechanism of cross-streamline migration by using soft capsules with a spherical equilibrium shape. If the viscosity varies perpendicular to the streamlines then the soft particles migrate across streamlines towards regions of a lower viscosity, even in linear shear flows. An interplay with the repulsive particle-boundary interaction causes then focusing of particles in linear shear flows with the attractor streamline closer to the wall in the low viscosity region. Viscosity variations perpendicular to the streamlines in Poiseuille flows leads either to a shift of the particle attractor or even to a splitting of particle attractors, which may give rise to interesting applications for particle separation. The location of attracting streamlines depend on the particle properties, like their size and elasticity. The cross-stream migration induced by viscosity variations is explained by analytical considerations, Stokesian dynamics simulations with a generalized Oseen tensor and lattice-Boltzmann simulations.

A Case of foreign body granuloma after Plastibell® circumcision

Male circumcision is one of the most commonly performed surgical procedures and the Plastibell® device is a popular method used to perform circumcisions in neonates and young children. We report a case of a 9-year-old otherwise healthy boy who developed foreign body granulomas following Plastibell® circumcision which was carried out in the community by a medically trained practitioner. His post-operative course was complicated by a retained Plastibell® ring and development of multiple non-healing wounds and granulomas. This patient underwent a semi-elective examination under general anesthesia, wound exploration and re-do modified circumcision. At 4 month follow up the wound was well healed without scarring and the patient reported a normal single straight stream urinary flow.

Investigating spatial variability of vertical water fluxes through the streambed in distinctive stream morphologies using temperature and head data

Investigating the interaction of groundwater and surface water is key to understanding the hyporheic processes. The vertical water fluxes through a streambed were determined using Darcian flux calculations and vertical sediment temperature profiles to assess the pattern and magnitude of groundwater/surface-water interaction in Beiluo River, China. Field measurements were taken in January 2015 at three different stream morphologies including a meander bend, an anabranching channel and a straight stream channel. Despite the differences of flux direction and magnitude, flux directions based on vertical temperature profiles are in good agreement with results from Darcian flux calculations at the anabranching channel, and the Kruskal-Wallis tests show no significant differences between the estimated upward fluxes based on the two methods at each site. Also, the upward fluxes based on the two methods show similar spatial distributions on the streambed, indicating (1) that higher water fluxes at the meander bend occur from the center of the channel towards the erosional bank, (2) that water fluxes at the anabranching channel are higher near the erosional bank and in the center of the channel, and (3) that in the straight channel, higher water fluxes appear from the center of the channel towards the depositional bank. It is noted that higher fluxes generally occur at certain locations with higher streambed vertical hydraulic conductivity (K v) or where a higher vertical hydraulic gradient is observed. Moreover, differences of grain size, induced by stream morphology and contrasting erosional and depositional conditions, have significant effects on streambed K v and water fluxes.

Hyporheic exchange controlled by dynamic hydrologic boundary conditions

AbstractThe relative roles of dynamic hydrologic forcing and geomorphology as controls on the timescales and magnitudes of stream‐aquifer exchange and hyporheic flow paths are unknown but required for management of stream corridors. We developed a comprehensive framework relating diel hydrologic fluctuations to hyporheic exchange in the absence of geomorphic complexity. We simulated groundwater flow through an aquifer bounded by a straight stream and hillslope and under time‐varying boundary conditions. We found that diel fluctuations can produce hyporheic flow path lengths and residence times that span orders of magnitude. With these results, hyporheic flow path residence times and lengths can be predicted from the timing and magnitude of diel fluctuations and valley slope. Finally, we demonstrated that dynamic hydrologic boundary conditions can produce spatial and temporal scales of hyporheic flow paths equivalent to those driven by many well‐studied geomorphic features, indicating that these controls must be considered together in future efforts of upscaling to stream networks.

Paleoflood discharge reconstruction in Tatra Mountain streams

Floods represent a common process in Tatra Mountain streams and may cause flood risk in the valleys of the Tatra foreland. Dealing with the hazards and risks caused by floods requires a detailed analysis of the frequency and magnitude of past and recent events. However, the Polish Tatra region is characterized by a scarcity of data on past floods in general and on systematic peak discharge in particular. In this study, we performed a paleohydrological analyses in four high-gradient mountain streams using scarred trees as paleostage indicators. We couple two-dimensional hydraulic modelling in a highly-resolved topographic environment (LiDAR data) with an important spatiotemporal data set of scars on trees to investigate (i) the magnitude of unrecorded major floods of the twentieth century, (ii) the effect of variability in geomorphic tree positions on the peak discharge reconstruction, and (iii) the impact of reconstructed events on the results of flood frequency analyses. The data set is based on a total of 55 scarred trees and allows peak discharge reconstruction of 16 major floods covering the last 113years. Results suggest that trees growing in straight stream reaches or in the inner side of channel bends would be better candidates for peak discharge reconstructions than trees located on the outer side of channel bends or growing in overbank sections with dense vegetation cover. The largest reconstructed flood is dated to 1903 with an estimated peak discharge of 115.9±59.2m3s−1, and larger-than-today floods are found to have occurred at Strążyska and Łysa Polana in the first half of the twentieth century. The inclusion of our results into the flood frequency analyses suggests that flood hazards might have been underestimated by up to 25.5% in the case of a 100-year flood in Strążyski Stream. In that sense, our findings will be useful for the design of future strategies dealing with flood risks in the foreland of the Polish Tatra Mountains.

Flow patterns of an air–water mixture at the exit of a micro T-junction

An experimental investigation of typical flow patterns in adiabatic gas–liquid mixture (air-water) generated in a micro T-junction varying the superficial velocity of the fluids is presented. The micro T-junction is made as intersection of two glass microchannels with a rectangular cross-section having a width of 300μm and a height of 256μm. The air–water mixture is obtained by means of an injection of air in perpendicular direction with respect to a straight stream of water. The air flow is broken in slugs having geometrical characteristics depending on the superficial velocity ratio imposed. Changing the air and water superficial velocity from 0.005m/s up to a maximum value of 0.15m/s, different kinds of intermittent slugs have been observed. In this way, a flow pattern map has been generated in order to reword the main characteristics of the intermittent slug flow generated after the T-junction as a function of the superficial air–water velocity ratio. In order to build the flow pattern map, 256 experimental runs characterized by different values of superficial velocity have been made. Different kinds of Taylor bubble flows have been observed during this experimental campaign: for a fixed low value of the air flow rate, by increasing the water flow rate it has been evidenced how the formation of the bubbles becomes faster and the length of the single bubble becomes shorter. A detailed discussion of the impact of the superficial air to water velocity ratio on the observed flow patterns is given.

Reliability of the FDS Simulating on Fire Extinguishing with Straight Stream of Compressed AFFF

By utilizing the fire dynamics simulation software FDS, simulate the fire extinguishing process of the diesel oil fire and gasoline fire with the compressed air foam agent, and compare it with the actual fire extinguishing test. Verify the reliability and the accuracy of the simulation implemented by FDS software on compressed air foam agent fire extinguishing process under the direct injection.

Snodgrass Tubularized Incised Plate Urethroplasty for Distal and Midpenile Hypospadias

Introduction: Despite hundreds of repair techniques for hypospadias, the introduction of tubularized incised plate urethroplasty (TIP) by Warren T. Snodgrass has become popular because of good functional and cosmetic outcome. The objective of this study was to share our experience of Snodgrass tubularized incised plate (TIP) urethroplasty for the repair of distal and mid-penile hypospadias. Materials and Methods: This prospective study was carried out for a period of 24 months. It included 46 male patients with the mean age of 4.1 years (18 months to 10 years). Proximal hypospadias and those distal with moderate to severe chordee were excluded. All cases underwent TIP urethroplasty as described by Snodgrass and the neourethra was covered by single or double layer of dorsal prepucial layer. The results were analyzed on the basis of duration of surgery, types of postoperative complications like urethrocutaneous fistula, meatal stenosis and wound dehiscence. Functional results assessed with ease of voiding, force and direction of urinary stream and cosmetic with external look of penis. Results: The overall complication rate requiring surgical intervention was 8 (17.3%). Mean duration of surgery was 66 minutes (60-80 minutes). Urethrocutaneous fistula occurred in 5 (10.8%), meatal stenosis in 1 (2.1%) and wound dehiscence in 2 (4.3%) patient. The cosmetic appearance was excellent in all patients involved in this study except 2 cases of wound dehiscence. All of them had vertically oriented slit like meatus with straight urinary stream. Conclusion: Tubularized incised plate urethroplasty gives good functional and excellent cosmetic results with low rate of complications in distal and mid-penile hypospadias. DOI: http://dx.doi.org/10.3126/jnps.v34i1.8692 J Nepal Paediatr Soc 2014;34(1):29-33

Spatial variability in streambed hydraulic conductivity of contrasting stream morphologies: channel bend and straight channel

AbstractStreambed hydraulic conductivity is one of the main factors controlling variability in surface water‐groundwater interactions, but only few studies aim at quantifying its spatial and temporal variability in different stream morphologies. Streambed horizontal hydraulic conductivities (Kh) were therefore determined from in‐stream slug tests, vertical hydraulic conductivities (Kv) were calculated with in‐stream permeameter tests and hydraulic heads were measured to obtain vertical head gradients at eight transects, each comprising five test locations, in a groundwater‐dominated stream. Seasonal small‐scale measurements were taken in December 2011 and August 2012, both in a straight stream channel with homogeneous elevation and downstream of a channel meander with heterogeneous elevation. All streambed attributes showed large spatial variability. Kh values were the highest at the depositional inner bend of the stream, whereas high Kv values were observed at the erosional outer bend and near the middle of the channel. Calculated Kv values were related to the thickness of the organic streambed sediment layer and also showed higher temporal variability than Kh because of sedimentation and scouring processes affecting the upper layers of the streambed. Test locations at the channel bend showed a more heterogeneous distribution of streambed properties than test locations in the straight channel, whereas within the channel bend, higher spatial variability in streambed attributes was observed across the stream than along the stream channel. Copyright © 2014 John Wiley & Sons, Ltd.

Evaluation of a solid stream radial nozzle on fixed-wing aircraft, for penetration of spray within a soybean canopy

Abstract Experiments were conducted to evaluate the Accu-Flo multiple orifice nozzle for penetration of spray into a soybean (Glycine max L.) canopy by comparing results to those from a popular straight stream nozzle and rotary atomizer. A mixture of water + Induce® adjuvant was applied at three different spray release heights in a random sequence, using an Air Tractor 402-B agricultural aircraft. Sampler stands were placed at twenty-four locations in the field. Water sensitive paper (WSP) cards were clipped onto rigid stands just above the canopy and 30 cm off the ground within the canopy. Weather data were recorded using two different stations on-site. Wind was predominantly from the west and parallel to the direction of the spray runs. The spray delivery systems compared were the Accu-Flo nozzles, (64 needle 0.020 opening), CP®-09 straight stream with 5 degree deflection, and Micronair® AU5000 atomisers (14 mesh screen) at a low volume spray rate of 18.7 l/ha. A total of 54 spray runs were made over three days, and heights were varied at 3.7 m, 4.9 m and 6.1 m. Water sensitive papers were scanned and analysed for coverage per unit card area using an image analysis system. Altitude and [Nozzle X Altitude] interaction were significant effects on coverage at the 0.01 and 0.07 significance levels, respectively, for the top cards. Nozzle type was not a significant effect on coverage for the top cards, but was significant at the 0.01 level for the bottom cards. Altitude alone had no obvious effect on coverage for the bottom cards, although it had an effect for the top cards. The highest percentage area of spray coverage was observed from the Accu-Flo nozzles, especially for the bottom cards. Average spray coverage from the Accu-Flo nozzles was 1.7 times higher than coverage from the CP® nozzles or Micronair® atomisers in the lower portion of the canopy.

Flow characteristics and morphological changes in open-channel flows with alternate vegetation zones

In this study, turbulent flows and morphological changes in an open-channel that has alternate vegetated zones are numerically simulated by using a three-dimensional model. The Reynolds-averaged Navier-Stokes Equations are solved with the k-ɛ model. The simulated flow structures compared well with the measured data in the literature. Through numerical experiments, the evolution of the mean flow and turbulence structures for different vegetation densities is presented. The vegetation was found to curve the flow, and the meandering flow pattern becomes more definite with increasing vegetation density. When the channel morphological changes are simulated with a series of floods, the initial rectangular channel becomes a compound channel and the flow pattern changes from a straight stream to a meandering stream. The evolution of vegetation zones after the floods indicates that vegetation zones are expanded in the leeward of the initial vegetation zones, and that the size of the vegetation zone is increased about 2.5 times.

Kutlay technique for hypospadias repair

Although many techniques have been described, new techniques with a wide range of therapeutic options are needed. The Kutlay technique is a novel technique that is based on the reconstruction of the neourethra with two horizontal meatal-based skin flaps. In the present study, the data of 31 patients who underwent surgery with the Kutlay technique are presented. Thirty-one patients with hypospadias with an average age of 5.6 years who did not have previous hypospadias repair were operated on with the Kutlay technique. Ten patients had chordee. Among those patients, three patients were circumcised. The patients were followed up for 4-13 months (average, 9.3 months). During the follow-up period, a fistula was observed in only one patient. None of the patients developed neourethral dehiscence, meatal stenosis, urethral stricture, wound infection, penile torsion, hematoma, or persistent or recurrent chordee. On uroflowmetry studies, the maximum flow rate of the patients was approximately 10.5 ml/s (range, 6-17 ml/s). The patients were observed to void with a single straight urinary stream in a forward direction. The Kutlay technique is a technique that is easily applied in patients with chordee and that provides a low risk of fistulas and acceptable functional and esthetic results. The factors that reduce the risk of fistula are the lack of the superposition of the suture lines of the skin and the urethra, the reconstruction of the urethra with well-vascularized flaps, and the replacement of the neourethra in its appropriate location through the tunnel created in the glans.

Fish assemblages composition in a natural, then regulated, stream: A quantitative long-term study

This paper tests the hypothesis how effectively fish assemblage composition was shaped by local climate changes and by engineering impact in 1989. This was possible due to the monitoring protocols of the present study, which allowed estimation of the magnitude of anthropogenic changes from changes naturally occurring in nature. Fish were sampled at the end of every growing season (October) for 23 years at five contiguous sites in a stream, before (1979–1988) and after (1989–2001) regulation. In each sample, six successive electrofishing passes were used to calculate the density and mean biomass for assemblage analysis using the Zippin model. During the study, the natural, meandering stream with pools, riffles, and a moderate canopy was modified into a straight stream of uniform width and depth, stripped of all vegetation. The output layer of a self-organizing map (SOM, the artificial neural network algorithm) applied in this study for site similarity analysis was partitioned into six subclusters placed in two main clusters. Subclusters in the upper part of the SOM were occupied chiefly by regulated stream samples and those in the lower part of the SOM by natural stream samples. Subclusters in the middle position, contained both natural (19) and regulated (20) samples in nearly equal proportion. In addition, the SOM contained one subcluster with sites only from the regulated period and another with only natural sites. Differences between subclusters were attributed to differences in climate, with some differences profound. Warming of the local weather, which became most evident in the 1990s, may have resulted in changes in fish assemblages. This is shown in the SOM, in which samples from the 1980s with cold years dominate the bottom of the SOM, whereas those from the 1990s and later are at the top. Subclusters dominated by regulated or natural sites were not always significantly different when the number of species and diversity indices were considered. Clear differences between the regulated and natural samples involved qualitative characteristics and mainly concerned assemblage composition. They were also confirmed by significant IndVal values (indicator species) and neither mixed subcluster contained important species in their assemblages.

Stream Depletion from Pumping a Semiconfined Aquifer in a Two-Layer Leaky Aquifer System

We consider the case of pumping a semiconfined aquifer overlain by a phreatic aquifer hydraulically connected to an infinitely long and straight stream. The hydraulics of the system are described by a linearized model in which it is assumed that flow in the aquifers is essentially horizontal, and that drawdown in the phreatic aquifer is small enough to allow the water table to be sufficiently well described by the Theis equation. Fourier-Laplace transforms of drawdown are obtained and numerically inverted. Comparisons are made with another well-known analytic model of Hunt, who considered a single aquifer/aquitard system. It is observed that while both models may have excellent agreement during the initial phase of pumping, the longer-term consequences of sustained pumping are quite distinct.

Effects of Different Suppression Tactics on the Firefighter and Compartment Environment

Effects of Different Suppression Tactics on the Firefighter and Compartment Environment MATTHEW OBACH, ELIZABETH WECKMAN, and ALLAN STRONG Department of Mechanical and Mechatronics Engineering University of Waterloo 200 University Ave. W. Waterloo, ON, N2L 3G1 ABSTRACT Experiments are conducted to study the effects of different water-based indirect initial attack methods on the compartment environment and firefighter during compartment fire suppression. Hot layer temperatures typical of room fire conditions are developed in the test compartment using wood cribs. Five suppression methods including straight stream, penciling, continuous wide and narrow fog, and a wide angle burst method are examined for two different spray angles and nozzle pressures. Temperatures, heat flux, gas velocity, and gas concentrations are monitored throughout the fire compartment. Realistic, yet extreme, fire conditions are repeatedly established in the test compartment, allowing up to nine tests per fire. Differences in average compartment temperature before and during suppression indicate that penciling tactics provide little cooling of the compartment. In narrow fog attacks, the hot layer is pushed toward the floor, resulting in increased temperatures in the lower layer, generally an undesired result. Wide angle fog methods have greater impact on compartment temperature as compared to straight stream or narrow fog methods; however, they may also result in large increases in temperature at the firefighter. Wide angle burst tactics less effectively cool the compartment gases than continuous methods, but also lead to less impact on the firefighter. Greater numbers of bursts increase cooling of the compartment, but at the expense of increased impact on the firefighter. Including impact on the firefighter, continuous straight stream methods, at a nozzle pressure of 700 kPa and aimed to the top of the rear compartment wall, appear the best choice for initial attack on fires developed in these experiments. Due to variability between real fire scenarios and experiments such as these, significantly more study of the various suppression tactics is required before the most effective methods of suppression can be determined even for a given set of fire scenarios.