The ability of a wet swale,constructed in an area of poor soil permeability,to manage runoff from a roadway was monitored through 27 storm events over a period of 8 months.During the monitoring period,the wet swale re...The ability of a wet swale,constructed in an area of poor soil permeability,to manage runoff from a roadway was monitored through 27 storm events over a period of 8 months.During the monitoring period,the wet swale reduced the total runoff volume by 50.4%through exfiltration and evapotranspiration.The wet swale significantly decreased the influent pollutant concentrations,and the effluent mean concentrations of total suspended solids,total phosphorus,chemical oxygen demand,ammonium,oxidized nitrogen,and total nitrogen in the effluent were 31 mg/L,0.10 mg/L,29 mg/L,0.52 mg/L,0.35 mg/L and1.28 mg/L,respectively.Pollutant loads were also substantially reduced from 70%to 85%.Plant uptake played an important role in nutrient removal in the wet swale.Approximately half of the nitrogen(53.8%)and phosphorus(51.5%)that entered the wet swale was incorporated in above-ground plants.It is shown that wet swales are useful for managing runoff from roads in areas of poor soil permeability.展开更多
Soil erosion induced by inappropriate tillage remains a serious problem on many agricultural fields in the humid tropics. Studies were conducted between 2004 and 2006, on an Alfisol in Ogbomoso in the Southern Guinea ...Soil erosion induced by inappropriate tillage remains a serious problem on many agricultural fields in the humid tropics. Studies were conducted between 2004 and 2006, on an Alfisol in Ogbomoso in the Southern Guinea Savanna of Nigeria to evaluate the effectiveness of Vetiver Grass(Vetiveria nigritana) Strips(VGS) under different tillage systems. The experiment was split-plot laid out in a randomized complete block design with two replications on 6% slope with 18 runoff plots. Main plot treatments were tillage systems; Manual Clearing(MC), Ploughing(P) and Ploughing plus Harrowing(PH). Subplot treatments were VGS spaced at intervals of 5 m(eight strips) and 10 m(four strips) with the control(no-vetiver). Runoffs and soil losses were collected after each major storm. Chemical analyses of eroded sediments and runoff were determined. Data were analyzed using ANOVA at p<0.05. The results showed that tillage had no significant reduction in runoffs and soil losses, but they were reduced with MC compared with P and PH. Mean total runoff on 5 and 10 m VGS plots were significantly(p<0.05) lower than that of the control by 74.4% and 45.0%, respectively. Corresponding soils loss on 5 and 10 m VGS plots were 27.1% and 53.5%, respectively. Mean NO3-N levels in runoff water were lower under PH plots than those under MC plots by 79.0% and 66.5%, respectively in 2004 and 2006 growing seasons. VGS spaced at 5 m significantly(p<0.05) reduced NO3-N loss than the control by 108.8% in 2004. Nutrients loads of eroded sediments were consistently higher for the control(no-vetiver) plots and least for 5 m VGS plot. Carbon, nitrogen and phosphorus contents of eroded sediments were 90%-92.4%, 83%-83.6% and 97%-97.8%, respectively, and were lower on 5 m than other treatments. Maize grain yield was significantly(p<0.05) affected by both tillage and VGS spacing only in 2005 growing season. P plot produced higher grain yield than MC and PH by 79.9% and 99.1%, respectively. Also, grain yield on VGS plot was significantly(p<0.05) higher on 5 and 10 m VGS plots than the control by 82.2% and 85.4%, respectively. The significant beneficial effect of PH in producing higher yields was dwarfed by the potential danger of soil erosion in the absence of a soil erosion control measure. The results showed that a balance needed to be struck between mechanical clearance and protective measure against soil erosion.展开更多
To improve the possible superelevation runoff models for the cycling track design,at first,two existing representative superelevation runoff models used in China were investigated and fitted. Then,an optimization meth...To improve the possible superelevation runoff models for the cycling track design,at first,two existing representative superelevation runoff models used in China were investigated and fitted. Then,an optimization methodology was proposed,which was focused on the track geometry itself,without the consideration of the physical characteristic of the cyclist,assuming that less vertical curvature values correspond to less riding time. The riding performance formulae were obtained with the variables of riding time,riding velocity and vertical curvature of cycling track. Finally,with the refined adjustment on the vertical curvatures with the help of cycling track design software and considering the effect of horizontal alignments,the optimized models were finalized. It is clearly seen that these optimized models take the form of quartic parabola and are verified to achieve 0.005-0.021 s improvement in the event of 200 m time trial.展开更多
The process of transformation of rainfall into runoff over a catchment is very complex and highly nonlinear and exhibits both tempor al and spatial variabilities. In this article, a rainfall-runoff model using th e ar...The process of transformation of rainfall into runoff over a catchment is very complex and highly nonlinear and exhibits both tempor al and spatial variabilities. In this article, a rainfall-runoff model using th e artificial neural networks (ANN) is proposed for simula ting the runoff in storm events. The study uses the data from a coa stal forest catchment located in Seto Inland Sea, Japan. This article studies the accuracy of the short-term rainfall forecast obta ined by ANN time-series analysis techniques and using antecedent rainfa ll depths and stream flow as the input information. The verification results from the proposed model indicate that the approach of ANN rai nfall-runoff model presented in this paper shows a reasonable agreement in rainfall-runoff modeling with high accuracy.展开更多
基金Project(2011ZX07303-002) supported by National Water Pollution Control and Management Technology Major Projects,China
文摘The ability of a wet swale,constructed in an area of poor soil permeability,to manage runoff from a roadway was monitored through 27 storm events over a period of 8 months.During the monitoring period,the wet swale reduced the total runoff volume by 50.4%through exfiltration and evapotranspiration.The wet swale significantly decreased the influent pollutant concentrations,and the effluent mean concentrations of total suspended solids,total phosphorus,chemical oxygen demand,ammonium,oxidized nitrogen,and total nitrogen in the effluent were 31 mg/L,0.10 mg/L,29 mg/L,0.52 mg/L,0.35 mg/L and1.28 mg/L,respectively.Pollutant loads were also substantially reduced from 70%to 85%.Plant uptake played an important role in nutrient removal in the wet swale.Approximately half of the nitrogen(53.8%)and phosphorus(51.5%)that entered the wet swale was incorporated in above-ground plants.It is shown that wet swales are useful for managing runoff from roads in areas of poor soil permeability.
文摘Soil erosion induced by inappropriate tillage remains a serious problem on many agricultural fields in the humid tropics. Studies were conducted between 2004 and 2006, on an Alfisol in Ogbomoso in the Southern Guinea Savanna of Nigeria to evaluate the effectiveness of Vetiver Grass(Vetiveria nigritana) Strips(VGS) under different tillage systems. The experiment was split-plot laid out in a randomized complete block design with two replications on 6% slope with 18 runoff plots. Main plot treatments were tillage systems; Manual Clearing(MC), Ploughing(P) and Ploughing plus Harrowing(PH). Subplot treatments were VGS spaced at intervals of 5 m(eight strips) and 10 m(four strips) with the control(no-vetiver). Runoffs and soil losses were collected after each major storm. Chemical analyses of eroded sediments and runoff were determined. Data were analyzed using ANOVA at p<0.05. The results showed that tillage had no significant reduction in runoffs and soil losses, but they were reduced with MC compared with P and PH. Mean total runoff on 5 and 10 m VGS plots were significantly(p<0.05) lower than that of the control by 74.4% and 45.0%, respectively. Corresponding soils loss on 5 and 10 m VGS plots were 27.1% and 53.5%, respectively. Mean NO3-N levels in runoff water were lower under PH plots than those under MC plots by 79.0% and 66.5%, respectively in 2004 and 2006 growing seasons. VGS spaced at 5 m significantly(p<0.05) reduced NO3-N loss than the control by 108.8% in 2004. Nutrients loads of eroded sediments were consistently higher for the control(no-vetiver) plots and least for 5 m VGS plot. Carbon, nitrogen and phosphorus contents of eroded sediments were 90%-92.4%, 83%-83.6% and 97%-97.8%, respectively, and were lower on 5 m than other treatments. Maize grain yield was significantly(p<0.05) affected by both tillage and VGS spacing only in 2005 growing season. P plot produced higher grain yield than MC and PH by 79.9% and 99.1%, respectively. Also, grain yield on VGS plot was significantly(p<0.05) higher on 5 and 10 m VGS plots than the control by 82.2% and 85.4%, respectively. The significant beneficial effect of PH in producing higher yields was dwarfed by the potential danger of soil erosion in the absence of a soil erosion control measure. The results showed that a balance needed to be struck between mechanical clearance and protective measure against soil erosion.
基金Project(BZ2008056) supported by Jiangsu International Cooperative Research Program in 2008, China
文摘To improve the possible superelevation runoff models for the cycling track design,at first,two existing representative superelevation runoff models used in China were investigated and fitted. Then,an optimization methodology was proposed,which was focused on the track geometry itself,without the consideration of the physical characteristic of the cyclist,assuming that less vertical curvature values correspond to less riding time. The riding performance formulae were obtained with the variables of riding time,riding velocity and vertical curvature of cycling track. Finally,with the refined adjustment on the vertical curvatures with the help of cycling track design software and considering the effect of horizontal alignments,the optimized models were finalized. It is clearly seen that these optimized models take the form of quartic parabola and are verified to achieve 0.005-0.021 s improvement in the event of 200 m time trial.
文摘The process of transformation of rainfall into runoff over a catchment is very complex and highly nonlinear and exhibits both tempor al and spatial variabilities. In this article, a rainfall-runoff model using th e artificial neural networks (ANN) is proposed for simula ting the runoff in storm events. The study uses the data from a coa stal forest catchment located in Seto Inland Sea, Japan. This article studies the accuracy of the short-term rainfall forecast obta ined by ANN time-series analysis techniques and using antecedent rainfa ll depths and stream flow as the input information. The verification results from the proposed model indicate that the approach of ANN rai nfall-runoff model presented in this paper shows a reasonable agreement in rainfall-runoff modeling with high accuracy.
