scholarly journals Development of Improved Drainage System for Storm Water flow at Isale koko Ilorin, Kwara State, Nigeria

2020 ◽  
Vol 5 (1) ◽  
Author(s):  
Olubunmi A Mokuolu ◽  
Victory E Evans ◽  
Wahab A Salami
Keyword(s):  
Rainfall Intensity ◽  
Rectangular Channel ◽  
Drainage System ◽  
Maximum Flow ◽  
Flood Disaster ◽  
Storm Water ◽  
Average Area ◽  
Reconnaissance Survey ◽  
Prone Area ◽  
Maximum Flow Velocity

Among areas prone to flood disaster yearly in Ilorin is Isale koko.  The study involved the reconnaissance survey to ascertain the current capacity of the existing drainage in the flood disaster prone area of Isale Koko, Ilorin, Kwara State, Nigeria. The dimension of the drainage network of the area was taken at eight (8) various points and the average area of the drainage was obtained to be 0.44m². The already existing drainage in the area was divided into 3 sections for easy computations of flow value, length, depth and width. The rainfall intensity for the study area was found to be 98.49mm/hr. The rational method and Manning’s equation were used for the surface runoff and the proposed drainage respectively. The peak flow of the area and maximum flow velocity in the drains were determined to be 48.46mᶟ/s and 2.21mᶟ/s respectively. The best hydraulic section method was employed to obtain new drainage dimensions for both rectangular and trapezoidal channels. The new designed rectangular channel had dimensions of 1.16m × 0.812m while the trapezoidal channel had dimensions of 1.43m×0.72m×0.87m. The area of both channels was obtained to be 0.67m². A comparative analysis was carried against the average area of the pre-existing drainage that showed a 53.3% increase in drainage area; proving that the current drainage infrastructure of the area is grossly inadequate. Sequel to the analysis, the trapezoidal shaped drainage was recommended for the study area. Keywords—Drainage, Flood, Infrastructure, Runoff, Storm water

scholarly journals Spatio-Temporal Variations in Phytoplankton Communities in Sediment and Surface Water as Reservoir Drawdown—A Case Study of Pengxi River in Three Gorges Reservoir, China

Water ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 340
Author(s):  
Wenjuan Ouyang ◽  
Zhe Li ◽  
Jixiang Yang ◽  
Lunhui Lu ◽  
Jinsong Guo
Keyword(s):  
Surface Water ◽  
Algal Blooms ◽  
Maximum Flow ◽  
Total Carbon ◽  
Hydrodynamic Conditions ◽  
Reservoir Drawdown ◽  
River Reservoir ◽  
Reservoir Systems ◽  
Spatio Temporal ◽  
Maximum Flow Velocity

The resting stages of phytoplankton are usually regarded as the seed bank and source of harmful algal blooms because of the recruitment of phytoplankton from sediment to the water column under suitable environmental conditions. Information about resting stages of phytoplankton is abundant in shallow lakes and littoral sea; yet, studies on river–reservoir systems are rare. The river–reservoir continuum shows a unique structuring of longitudinal gradients of hydrological and hydrodynamic conditions. We hypothesized that the seed bank and algal blooms in reservoirs are influenced by the hydrodynamic conditions of each reservoir. We used Illumina Miseq sequencing to examine the spatio-temporal variation in the phytoplankton community in the sediment as reservoir drawdown and in surface water during algal blooms in Pengxi River, a tributary of China’s Three Gorges Reservoir. The results show that the cyanobacteria community in sediment is significantly influenced by temperature, total carbon, maximum flow velocity, and total phosphorous, the eukaryotic phytoplankton community in sediment is significantly influenced by total phosphorous, temperature, total carbon, maximum flow velocity, and total nitrogen. Additionally, the dominant species in sediment is significantly different from that in surface water during algal blooms. Our results suggest that the dominant species in surface water during algal blooms is more influenced by the environmental factors and hydrodynamic conditions in the water column than the seeds in the sediment. These findings are fundamental for further research on the influence of hydrodynamic conditions on algal blooms in artificially regulated river-reservoir systems.

scholarly journals The mechanical origin of snow avalanche dynamics and flow regime transitions

2020 ◽  
Author(s):  
Xingyue Li ◽  
Betty Sovilla ◽  
Chenfanfu Jiang ◽  
Johan Gaume
Keyword(s):  
Flow Velocity ◽  
Alpha Angle ◽  
Maximum Flow ◽  
Flow Regimes ◽  
Snow Avalanche ◽  
Snow Avalanches ◽  
Deposition Zone ◽  
Avalanche Dynamics ◽  
Maximum Flow Velocity ◽  
Deposit Height

Abstract. Snow avalanches cause fatalities and economic damages. Key to their mitigation entails the understanding of snow avalanche dynamics. This study investigates the dynamic behaviors of snow avalanches, using the Material Point Method (MPM) and an elastoplastic constitutive law for porous cohesive materials. By virtue of the hybrid Eulerian-Lagrangian nature of MPM, we can handle processes involving large deformations, collisions and fractures. Meanwhile, the elastoplastic model enables us to capture the mixed-mode failure of snow, including tensile, shear and compressive failure. Using the proposed numerical approach, distinct behaviors of snow avalanches, from fluid-like to solid-like, are examined with varied snow mechanical properties. In particular, four flow regimes reported from real observations are identified, namely, cold dense, warm shear, warm plug and sliding slab regimes. Moreover, notable surges and roll-waves are observed peculiarly for flows in transition from cold dense to warm shear regimes. Each of the flow regimes shows unique flow characteristics in terms of the evolution of the avalanche front, the free surface shape, and the vertical velocity profile. We further explore the influence of slope geometry on the behaviors of snow avalanches, including the effect of slope angle and path length on the maximum flow velocity, the $\\alpha$ angle and the deposit height. Unified trends are obtained between the normalized maximum flow velocity and the scaled $\\alpha$ angle as well as the scaled deposit height, reflecting analogous rules with different geometry conditions of the slope. It is found the maximum flow velocity is mainly controlled by the friction between the bed and the flow, the geometry of the slope, and the snow properties. In addition to the flow behavior before reaching the deposition zone, which has long been regarded as the key factor governing the $\\alpha$ angle, we reveal the crucial effect of the stopping behavior in the deposition zone. Furthermore, our MPM model is benchmarked with simulations of real snow avalanches. The evolution of the avalanche front position and velocity from the MPM modeling shows reasonable agreement with the measurement data from literature. The MPM approach serves as a novel and promising tool to offer systematic and quantitative analysis for mitigation of gravitational hazards like snow avalanches.

scholarly journals CURRENT STATUS OF URBAN DRAINAGE SYSTEM AND ITS PROBLEM IN NETROKONA MUNICIPAL, DHAKA

2017 ◽  
Vol 22 (1) ◽  
pp. 165-178
Author(s):  
Rajon Kanti Datta ◽  
Ohidul Alam ◽  
Mohammad Mozaffar Hossain
Keyword(s):  
Public Health ◽  
Drainage System ◽  
Simple Random Sampling ◽  
Current Status ◽  
Primary Data ◽  
Urban Drainage ◽  
Urban Drainage System ◽  
Reconnaissance Survey ◽  
The Status ◽  
Structured Questionnaire

Rapid and haphazard urbanization has triggered environmental hazards in Bangladesh. Analogously, Netrokona Municipal is also facing problems due to unplanned and unstable urban infrastructural development. The quest of the study was to explore the status of current urban drainage system and its problem. Therefore, a preliminary reconnaissance survey was accomplished in the study area and then a semi-structured questionnaire was designed. By adopting simple random sampling method, the study area was surveyed covering 50 respondents in different wards to collect primary data. Results revealed that poor drainage system (PDS) is one of the most liable factors for environmental deterioration. The maximum urban drainage system was found unclosed with number of 49 (i.e., 98%). It was 34 drains were made of brick, while 17 were worst type, 32 had odor problem, 20 were not well designed, 29 had inadequacy of drains,18 with poor technical fitness, 22 wastes disposal in gutters,18 had clogging of ditches & drains, and 15 with broken road surface respectively. The consequent major environmental and health problems were flash-flooding (42%), and skin disease (38%) respectively. In case of public opinion, the highest percentage (i.e., 30%) suggested to stoutly prohibit dumping of garbage into gutters. PDS was found strongly positive correlated with its effects on environment (r=0.98) and on public health (r=0.91). Thereby, present PDS affects the environment as-well-as public health by enhancing frequent flash-floods and spreading diseases within the study area.Journal of Institute of Science and TechnologyVolume 22, Issue 1, July 2017, Page: 165-178

The Application of SWMM in the Analysis of a Campus Drainage System

2015 ◽  
Vol 744-746 ◽  
pp. 1146-1150
Author(s):  
Zheng Rong Fu ◽  
Jia Xin Zhuang ◽  
Liang Zhu Wang
Keyword(s):  
Water Management ◽  
Return Period ◽  
Drainage System ◽  
Storm Water ◽  
Management Model ◽  
University Campus ◽  
Storm Water Management Model ◽  
Design Storm ◽  
Road Base ◽  
One Year

The drainage system of a part of a university campus was tapped using SWMM (Storm Water Management Model). Local drainage discharge capacity was studied under different design storm return period. Results show that flooding and overload at some junctions and in some conduits are doubled with the increase of design rain return period from one year to five year, which may deteriorate the traffic and road base.

scholarly journals Simulation studies of storm water drainage in Wrocław

2018 ◽  
Vol 44 ◽  
pp. 00129
Author(s):  
Monika Nowakowska
Keyword(s):  
Hydrodynamic Model ◽  
Drainage System ◽  
Storm Water ◽  
Simulation Studies ◽  
Water Drainage ◽  
Residential Areas ◽  
Residential Communities ◽  
Flood Volume ◽  
Maximum Water ◽  
Water Impoundment

In the paper were made the verification of the operation of a rainwater drainage system in the residential communities of Gaj and Tarnogaj in Wrocław, carried out in the hydrodynamic model using SWMM software. There were used two criterial precipitation: Euler’s model (with a frequency of C = 3 years) and the actual precipitation (C = 5 years). The criteria of overloading the system was the specific flood volume (SFV). For both cases of precipitation load of catchment, the simulated calculations showed the occurrence of outflows from the channels. Due to the value of SFV indicator (respectively: 19 m3/ha and 42,9 m3/ha), it was found that the tested system needs modernization, therefor acceptable instantaneous water level above the maximum water impoundment were more often than 1 per 3 years, which leads to overflows from channels for residential areas more often than allowed once every 20 years.

Comparative study of transcranial color duplex sonography and transcranial Doppler sonography in adults

1993 ◽  
Vol 78 (5) ◽  
pp. 776-784 ◽  
Author(s):  
Martin Schöoning ◽  
Reiner Buchholz ◽  
Jochen Walter
Keyword(s):  
Flow Velocity ◽  
Doppler Sonography ◽  
Transcranial Doppler Sonography ◽  
Maximum Flow ◽  
Duplex Sonography ◽  
Color Duplex Sonography ◽  
Content Type ◽  
Maximum Flow Velocity ◽  
Fine Print ◽  
Flow Velocities

✓ To determine whether the frequency shift recorded in basal cerebral arteries corresponds to “true” flow velocities, a prospective comparative study of transcranial color duplex sonography (TCCD) and transcranial Doppler sonography (TCD) was performed. A 2.0-MHz transducer of a computerized TCCD system and a TCD device were used. The middle cerebral artery (MCA) and anterior cerebral artery (ACA) were examined by TCCD in 49 healthy volunteers (mean age 35 ± 12 years). In 45 of the same volunteers a comparative TCD examination was possible. The studies were carried out blindly by different examiners at separate appointments. Peak systolic flow velocity, end-diastolic maximum flow velocity, time-averaged maximum flow velocity, and the pulsatility index were measured by both techniques. Additionally, for TCCD, time-averaged flow velocity was assessed, the resistance index and a spectral broadening index were calculated, and the energy output required for reliable measurement was analyzed. The TCCD signals were recorded in 98% of both MCA's and ACA's; with TCD, signals were recorded in 98% of MCA's and 87% of ACA's. Although in both vessels the angle-corrected peak systolic and time-averaged maximum velocities were approximately 10% to 15% higher in TCCD than in TCD measurements, correlation of flow velocities between both techniques was significant (p < 0.0001); differences between sides and age-dependency of flow velocities corresponded as well. In a reproducibility study, TCCD was repeated in 27 subjects by a third examiner with significant correlation (p < 0.0001) of both TCCD examinations. It is concluded that the advantage of TCCD is associated more with a qualitative aspect than a quantitative one. The additional visual dimension of TCCD can open new diagnostic possibilities in cerebrovascular disorders.

Sign in / Sign up

Export Citation Format

Share Document