Sediment behaviour in grass filter strips

Sediment transport was studied in non-submerged overland flow over grass in a laboratory. Artificial turf (astro-turf) was used to simulate natural grass and no infiltration was allowed at this stage of the investigation. Experiments were conducted for different grass densities, flow rates, sediments inflows, and sediment types. It was observed that concentration of sediment in runoff decreases exponentially with the distance and reaches asymptotically a constant value. Measured sediment deposition was compered with the results calculated by the Kentucky model (tollner et al., 1976). The model over-predicted grossly the trapping efficiency of all particle fractions, but it is unreliable particularly for small particles. A new simplified relationship was established between particle fall number, Nf, and percentage of particles trapped in the grass. The relationship should be verified on natural grass before it is used in practice. Finally, infiltration of water and particles should be studied on natural turf, as well as, influence of grass blades bending, before the complex model of sediment behaviour in grass is established.

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The performance of grass filter strips in controlling high-concentration suspended sediment from overland flow under rainfall/non-rainfall conditions

Earth Surface Processes and Landforms ◽

10.1002/esp.3393 ◽

2013 ◽

pp. n/a-n/a ◽

Cited By ~ 3

Author(s):

Lan Ma ◽

Chengzhong Pan ◽

Yanguo Teng ◽

Zhouping Shangguan

Keyword(s):

Suspended Sediment ◽

Overland Flow ◽

High Concentration ◽

Filter Strips ◽

Grass Filter Strips

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Hydrologic design aid for urban grass filter strips

Water and Environment Journal ◽

10.1111/wej.12155 ◽

2015 ◽

Vol 30 (1-2) ◽

pp. 4-13 ◽

Cited By ~ 1

Author(s):

A. Osman Akan ◽

Serter Atabay

Keyword(s):

Filter Strips ◽

Grass Filter Strips ◽

Hydrologic Design

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Overland Flow Resistance Law under Sparse Stem Vegetation Coverage

Water ◽

10.3390/w13121657 ◽

2021 ◽

Vol 13 (12) ◽

pp. 1657

Author(s):

Jingzhou Zhang ◽

Shengtang Zhang ◽

Si Chen ◽

Ming Liu ◽

Xuefeng Xu ◽

...

Keyword(s):

Flow Resistance ◽

Overland Flow ◽

Vegetation Coverage ◽

Dominant Factor ◽

Roughness Coefficient ◽

Hydraulic Parameters ◽

Slope Condition ◽

Manning Roughness ◽

The Relationship ◽

Manning Roughness Coefficient

To explore the characteristics of overland flow resistance under the condition of sparse vegetative stem coverage and improve the basic theoretical research of overland flow, the resistance characteristics of overland flow were systematically investigated under four slope gradients (S), seven flow discharges (Q), and six degrees of vegetation coverage (Cr). The results show that the Manning roughness coefficient (n) changes with the ratio of water depth to vegetation height (h/hv) while the Reynolds number (Re), Froude number (Fr), and slope (S) are closely related to vegetation coverage. Meanwhile, h/hv, Re, and Cr have strong positive correlations with n, while Fr and S have strong negative correlations with n. Through data regression analysis, a power function relationship between n and hydraulic parameters was observed and sensitivity analysis was performed. It was concluded that the relationship between n and h/hv, Re, Cr, Q, and S shows the same law; in particular, for sparse stem vegetation coverage, Cr is the dominant factor affecting overland flow resistance under zero slope condition, while Cr is no longer the first dominant factor affecting overland flow resistance under non-zero slope condition. In the relationship between n and Fr, Cr has the least effect on overland flow resistance. This indicates that when Manning roughness coefficient is correlated with different hydraulic parameters, the same vegetation coverage has different effects on overland flow resistance. Therefore, it is necessary to study overland flow resistance under the condition of sparse stalk vegetation coverage.

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The Effect of Discrimination on Stress among Public Housing Residents: A Comparative Study between Social-Mix and Independent Public Housing Complexes

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph17186788 ◽

2020 ◽

Vol 17 (18) ◽

pp. 6788 ◽

Cited By ~ 1

Author(s):

Hee-Jung Jun ◽

Soojeong Han

Keyword(s):

Public Housing ◽

Panel Study ◽

Study Data ◽

Complex Model ◽

Social Mix ◽

Lower Effect ◽

Housing Complex ◽

Public Housing Residents ◽

The Relationship ◽

The Empirical Analysis

This study aims to examine the differential effect of discrimination on stress between social-mix and independent public housing complexes. We analyzed the 2017 Seoul Public Housing Residents Panel Study data that were collected from public housing residents living in Seoul, Korea by running ordinal logit analyses. The empirical analysis shows that discrimination has a lower effect on stress in social-mix housing complexes than in independent public housing complexes. In addition, the moderating effect of community-based activities on the relationship between discrimination and stress was found in the independent public housing complex model.

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Effects of Playing Surface on Physical, Physiological, and Perceptual Responses to a Repeated-Sprint Ability Test: Natural Grass Versus Artificial Turf

International Journal of Sports Physiology and Performance ◽

10.1123/ijspp.2018-0766 ◽

2019 ◽

Vol 14 (9) ◽

pp. 1219-1226 ◽

Cited By ~ 1

Author(s):

Achraf Ammar ◽

Stephen J. Bailey ◽

Omar Hammouda ◽

Khaled Trabelsi ◽

Nabil Merzigui ◽

...

Keyword(s):

Physical Performance ◽

Perceived Exertion ◽

C Reactive Protein ◽

Artificial Turf ◽

Ratings Of Perceived Exertion ◽

Reactive Protein ◽

Repeated Sprint Ability ◽

Natural Grass ◽

Repeated Sprint ◽

Feeling Scale

Purpose: The effect of playing surface on physical performance during a repeated-sprint ability (RSA) test and the mechanisms for any potential playing-surface-dependent effects on RSA performance are equivocal. The purpose of this study was to investigate the effect of natural grass (NG) and artificial turf (AT) on physical performance, ratings of perceived exertion, feeling scale, and blood biomarkers related to anaerobic contribution (blood lactate [Lac]), muscle damage (creatine kinase and lactate dehydrogenase), inflammation (C-reactive protein), and immune function (neutrophils [NEU], lymphocytes [LYM], and monocytes) in response to an RSA test. Methods: A total of 9 male professional football players from the same regional team completed 2 sessions of RSA testing (6 × 30 s interspersed with a 35-s recovery) on NG and AT in a randomized order. During the RSA test, total (sum of distances) and peak (highest distance covered in a single repetition) distance covered were determined using a measuring tape, and the decrement in sprinting performance from the first to the last repetition was calculated. Before and after the RSA test, ratings of perceived exertion, feeling scale, and Lac, creatine kinase, lactate dehydrogenase, C-reactive protein, NEU, LYM, and monocytes were recorded in both NG and AT conditions. Results: Although physical performance declined during the RSA blocks on both surfaces (P = .001), the distance covered declined more on NG (15%) than on AT (11%; P = .04; effect size [ES] = −0.34; 95% confidence interval [CI], −1.21 to 0.56) with a higher total distance covered (+6% [2%]) on AT (P = .018; ES = 1.15; 95% CI, 0.16 to 2.04). In addition, lower ratings of perceived exertion (P = .04; ES = −0.49; 95% CI, −1.36 to 0.42), Lac, NEU, and LYM (P = .03; ES = −0.80; 95% CI, −1.67 to 0.14; ES = −0.16; 95% CI, −1.03 to 0.72; and ES = −0.94; 95% CI, −1.82 to 0.02, respectively) and more positive feelings (P = .02; ES = 0.81; 95% CI, −0.13 to 1.69) were observed after the RSA test performed on AT than on NG. No differences were observed in the remaining physical and blood markers. Conclusion: These findings suggest that RSA performance is enhanced on AT compared with NG. This effect was accompanied by lower fatigue perception and Lac, NEU, and LYM and a more pleasurable feeling. These observations might have implications for physical performance in intermittent team-sport athletes who train and compete on different playing surfaces.

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Epidemiology of Anterior Cruciate Ligament Injury on Natural Grass Versus Artificial Turf in Soccer: 10-Year Data From the National Collegiate Athletic Association Injury Surveillance System

Orthopaedic Journal of Sports Medicine ◽

10.1177/2325967120934434 ◽

2020 ◽

Vol 8 (7) ◽

pp. 232596712093443

Author(s):

Mark Howard ◽

Samantha Solaru ◽

Hyunwoo P. Kang ◽

Ioanna K. Bolia ◽

George F.R. Hatch ◽

...

Keyword(s):

National Collegiate Athletic Association ◽

Cruciate Ligament ◽

Injury Rate ◽

Acl Injury ◽

Soccer Players ◽

Artificial Turf ◽

Injury Surveillance System ◽

Injury Rates ◽

Natural Grass ◽

Anterior Cruciate

Background: Anterior cruciate ligament (ACL) injury is prevalent among National Collegiate Athletic Association (NCAA) soccer players. Controversy remains regarding the effect of the surface type on the rate of ACL injury in soccer players, considering differences in sex, type of athletic exposure, and level of competition. Hypothesis: Natural grass surfaces would be associated with decreased ACL injury rate in NCAA soccer players. Sex, type of athletic exposure (match vs practice), and level of competition (Division I-III) would affect the relationship between playing surface and ACL injury rates. Study Design: Cohort study; Level of evidence, 3. Methods: Using the NCAA Injury Surveillance System (ISS) database, we calculated the incidence rate of ACL injury in men and women from 2004-2005 through 2013-2014 seasons. The incidence was normalized against athletic exposure (AE). Additional data collected were sex, athletic activity at time of injury (match vs practice), and level of competition (NCAA division) to stratify the analysis. Statistical comparisons were made by calculating incidence rate ratios (IRR). Statistical significance was set at an alpha of .05. Results: There were 30,831,779 weighted AEs during the study period. The overall injury rate was 1.12 ACL injuries per 10,000 AEs (95% CI, 1.08-1.16). Women comprised 57% of the match data (10,261 games) and 55% of practice data (26,664 practices). The overall injury rate was significantly higher on natural grass (1.16/10,000 AEs; 95% CI, 1.12-1.20) compared with artificial turf (0.92/10,000 AEs [95% CI, 0.84-1.01]; IRR, 1.26 [95% CI, 1.14-1.38]) ( P < .0001). This relationship was demonstrated consistently across all subanalyses, including stratification by NCAA division and sex. The injury rate on natural grass (0.52/10,000 AEs; 95% CI, 1.11-1.26) was significantly greater than the injury incidence during practice on artificial turf (0.06/10,000 AEs; 95% CI, 0.043-0.096). Players were 8.67 times more likely to sustain an ACL injury during practice on natural grass compared with practice on artificial turf (95% CI, 5.43-12.13; P < .0001). No significant difference was found in injury rates between matches played on grass versus turf (IRR, 0.93; 95% CI, 0.84-1.03; P = .15). Conclusion: NCAA soccer players who practice on natural grass have increased risk of ACL injury compared with the risk of those practicing on an artificial surface, regardless of sex or NCAA division of play. No difference in risk of ACL injury between playing surfaces was detected during matches. Further research is necessary to examine the effect of multiple factors when evaluating the effect of the surface type on the risk of ACL injury in soccer players.

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Injury Surveillance in Major League Soccer: A 4-Year Comparison of Injury on Natural Grass Versus Artificial Turf Field

The American Journal of Sports Medicine ◽

10.1177/0363546519860522 ◽

2019 ◽

Vol 47 (10) ◽

pp. 2279-2286 ◽

Cited By ~ 2

Author(s):

Sean P. Calloway ◽

David M. Hardin ◽

Matthew D. Crawford ◽

J. Michael Hardin ◽

Lawrence J. Lemak ◽

...

Keyword(s):

Incidence Rate ◽

Ankle Injury ◽

Injury Incidence ◽

Artificial Turf ◽

Natural Grass ◽

Injury Data ◽

Major League Soccer ◽

Foot Injury ◽

Major League ◽

Elite Level

Background: Artificial playing surfaces are becoming more common due to decreased cost of maintenance and increased field usability across different environmental conditions. The Fédération Internationale de Football Association (FIFA) has approved newer generation artificial turf for soccer competition at the elite level, but many elite-level athletes prefer to play on natural grass surfaces due to a perceived increase in injury rate, discomfort, and fatigability on artificial turf. Hypothesis: Injury rates and rates of individually categorized types of injury experienced on artificial turf are noninferior to rates of injury on the standard comparator, natural grass, in elite-level Major League Soccer athletes. Study Design: Cohort study; Level of evidence, 2. Methods: Over the course of 4 Major League Soccer seasons (2013-2016), athlete injury data were recorded electronically. Injury data recorded in matches between 2 Major League Soccer teams were then analyzed. Playing surface was known for each venue, and all artificial turf surfaces were rated as 2-star according to FIFA criteria. Incidence rate ratios (Artificial Turf ÷ Natural Grass) were calculated with a 95% CI (α = .05) for both overall injury incidence and individual injury subgroups. A noninferiority margin (δ) of 0.15 was used to determine noninferiority of injury incidence rates. Results: A total of 2174 in-game injuries were recorded during the study period, with 1.54 injuries per game on artificial turf and 1.49 injuries per game on natural grass (incidence rate ratio, 1.033; 95% CI, 0.937-1.139). Within injury subgroups, overall ankle injury, Achilles injury, and ankle fracture were found to have a statistically higher incidence on artificial turf. Artificial turf was found to be noninferior to natural grass for overall foot injury and forefoot injury. No statistically significant differences were found in knee injuries between the 2 surfaces. Conclusion: The overall rate of injury on artificial turf was noninferior to that on natural grass. Within individual injury categories, a higher rate of ankle injury was found on artificial turf. No other injury subgroup demonstrated statistically significant differences between surfaces. Clinical Relevance: FIFA 2-star rated artificial turf is a viable alternative to natural grass in elite-level soccer competition. Innovative research methods for comparing artificial turf versus natural grass may elucidate relative advantages with respect to player safety.

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The Effect Of Playing Surface On Anterior Cruciate Ligament Injury In NCAA Soccer

Orthopaedic Journal of Sports Medicine ◽

10.1177/2325967120s00125 ◽

2020 ◽

Vol 8 (3_suppl2) ◽

pp. 2325967120S0012

Author(s):

Mark Howard ◽

Hyunwoo Paco Kang ◽

Samantha Solaru ◽

Alexander E. Weber ◽

Mark F. Rick C

Keyword(s):

Anterior Cruciate Ligament ◽

Cruciate Ligament ◽

Acl Injury ◽

Soccer Players ◽

Injury Incidence ◽

Artificial Turf ◽

Acl Injuries ◽

Natural Grass ◽

Significant Difference ◽

Anterior Cruciate

Objectives: Previous orthopaedic literature has examined the effect of synthetic playing surfaces on the risk of anterior cruciate ligament (ACL) injury in athletes and produced varying and inconclusive results. The objective of this study was to examine the role of playing surface on the incidence and risk of ACL injury in collegiate soccer athletes. Methods: The NCAA Injury Surveillance Program (ISP) database was queried for ACL injuries for male and female soccer players from the 2004-05 through the 2013-14 seasons at all levels of competition. The number of athlete exposures (AEs), defined as 1 athlete participating in 1 practice or competition in which they were exposed to the possibility of athletic injury, were recorded for grass and synthetic playing surfaces. Both the reported injuries and exposures provided were weighted in order to represent the entire NCAA collegiate soccer population. Normalized ACL incidence rates were calculated as well as 95% confidence intervals (95%CI). Rate ratios comparing competition type amongst both competition and practice were calculated. Results: ACL injuries were more common on grass surfaces (1.16 per 10,000 AEs, 95%CI 1.12-1.20) than artificial turf (0.92 per 10,000 AEs, 95%CI 0.84-1.04). This difference was statistically significant (IRR 1.26, p<0.0001), and driven primarily by the difference in injury incidence during practice. The injury incidence during practice on natural grass (1.18 per 10,000 AEs, 95% CI 1.11-1.26) was significantly greater than the injury incidence rate during practice on artificial turf (0.067 per 10,000 AEs, 95%CI 0.043-0.096). Players were 17.7 times more likely (95%CI 10.6678-27.2187, p<0.0001) to sustain an ACL injury during practice on natural grass when compared to practice on artificial turf. However, there was no significant difference in injury incidence during matches (IRR 0.96, p=0.44), with matches on natural grass (3.35 per 10,000 AEs, 95% CI 3.21-3.51) equivalent to matches on artificial surfaces (3.49 per 10,000 AEs, 95%CI 3.18-3.81). When comparing exposure type, the injury rate was significantly greater during matches (3.38 per 10,000 AEs, 95% CI 3.25-3.52) compared to practices (0.82 per 10,000 AEs, 95%CI 0.77-0.88), with a 4.10-fold increase in ACL injury incidence during matches compared to practice (p<0.0001). Conclusion: Between 2004 and 2014, NCAA soccer players experienced a greater number of ACL injuries on natural grass playing surfaces compared with artificial turf playing surfaces. This difference is driven by injuries during practice, where athletes were nearly 18 times more likely to suffer an ACL injury on grass versus artificial turf. While ACL injuries were more likely during matches compared to practices, no difference in incidence was noted between playing surfaces. Additional study is warranted investigating potential causes for this observed increased risk with soccer practice on grass fields.

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