Performance Of Drainage Systems Research Articles

Synchronous LoRa Mesh Network to Monitor Processes in Underground Infrastructure

Collecting precise real-time information on urban drainage system performance is essential to identify, predict, and manage critical loading situations, such as urban flash floods and sewer overflows. Although emerging low-power wireless communication techniques allow efficient data transfers with great above-ground performance, for underground or indoor applications in a large coverage range are difficult to achieve due to physical and topological limitations, particularly in dense urban areas. In this paper, we first discuss the range limitations of the LoRaWAN standard based on a systematic evaluation of a long-term operation of a sensor network monitoring in-sewer process dynamics. Analyses reveal an-on average-five-fold higher data packet loss for sub-surface nodes, which steadily grows with increasing distance to the gateway. Second, we present a novel LPWAN concept based on the LoRaR technology that enhances transmission reliability, efficiency, and flexibility in range-critical situations through meshed multi-hop routing and ensures a precise time-synchronization through optional GPS or DCF77 long-wave time signaling. Third, we illustrate the usefulness of the newly developed concept by evaluating the radio transmission performance for two independent full-scale field tests. Test results show that the synchronous LoRa mesh network approach clearly outperforms the standard LoRaWAN technique with regard to the reliability of packet delivery when transmitting from range-critical locations. Hence, the approach is expected to generally ease data collection from difficult-to-access locations such as underground areas.

Mitigating particle and nutrient losses via subsurface agricultural drainage using lightweight aggregates

The awareness of sediment and nutrient loss from non-point sources are of increasing environmental concern as measures to reduce point source inputs to surface waters have been introduced. Mitigation efforts to reduce loss of particles and nutrients from agriculture in Norway and other countries have mainly focused on surface runoff, whereas sub-surface drainage has received little attention. However, research has shown that the sub-surface field drains are transporting both sediment and nutrients rapidly to the watercourses. Despite these established facts there has been little development of measures to reduce these losses. This article describes how Lightweight Aggregates (LWA), Leca®, can mitigate some of the environmental challenges connected to sub-surface field drains.A field experimental project was performed to assess the effects on drainage water quality hydrological performance and functionality of drainage systems based on Lightweight Aggregates compared to traditional pipe drains. Registrations of the performance of the systems were done in two separate periods, 1992–1993 and 1999–2000. After 2000 no measurement programme has run. The functionality of the drainage systems was registered in connection to ordinary farming activity.In 1999–2000 LWA drains showed particularly good performance with regard to reducing the content of Phosphorus, 40–90 % reduction in Total-P. The drainage water from the LWA drains contained less than half the amount of suspended solids compared to traditional pipe drains. The results from 1993 showed no significant difference between LWA drains and pipe drains with respect to Nitrogen. The results from 1999/2000 showed higher loss of Nitrogen through pipe drains with no envelope compared to all other systems.LWA drains may be particularly useful in reducing particles and nutrient loads from cultivated flat drained areas adjacent to environmentally sensitive and ecologically important water ecosystems. Further investigations are recommended to optimise the design of LWA drains.

Impacts of Climate Change on Urban Extreme Rainfall and Drainage Infrastructure Performance: A Case Study in Wuhan City, China

AbstractThe design of stormwater drainage infrastructure in urban areas in China is based on the statistical stationary assumption of probability distribution of extreme rainfall, which is being increasingly challenged by climate change. However, quantitative assessment of the performance of urban drainage systems in response to climate change with the latest emission scenarios of the Coupled Model Intercomparison Project Phase 5 in China is quite limited. This study aims to investigate potential changes of extreme rainfall and their influence on drainage infrastructure in a representative urban area in Wuhan city, China. The Storm Water Management Model is established to investigate the response of drainage infrastructure to future design rainfall. It is found that the probability distribution of extreme rainfall for two historical sub‐periods (1961–1985 and 1986–2005) has changed, especially in the head and tail of the frequency curves. Furthermore, the design rainfall with return periods of 2, 3, 4 and 5 years increases more significantly than those of 10 and 20 years. Consequently, the incapability of the current drainage infrastructure in the study area is aggravated. Moreover, the results of SWMM modelling provide detailed information about the performance of current drainage infrastructure, which can provide technical support for future modifications of the current drainage infrastructure of the study area. © 2018 John Wiley & Sons, Ltd.

Comparison of urbanization and climate change impacts on urban flood volumes: Importance of urban planning and drainage adaptation

Understanding the drivers behind urban floods is critical for reducing its devastating impacts to human and society. This study investigates the impacts of recent urban development on hydrological runoff and urban flood volumes in a major city located in northern China, and compares the urbanization impacts with the effects induced by climate change under two representative concentration pathways (RCPs 2.6 and 8.5). We then quantify the role of urban drainage system in mitigating flood volumes to inform future adaptation strategies. A geo-spatial database on landuse types, surface imperviousness and drainage systems is developed and used as inputs into the SWMM urban drainage model to estimate the flood volumes and related risks under various urbanization and climate change scenarios. It is found that urbanization has led to an increase in annual surface runoff by 208 to 413%, but the changes in urban flood volumes can vary greatly depending on performance of drainage system along the development. Specifically, changes caused by urbanization in expected annual flood volumes are within a range of 194 to 942%, which are much higher than the effects induced by climate change under the RCP 2.6 scenario (64 to 200%). Through comparing the impacts of urbanization and climate change on urban runoff and flood volumes, this study highlights the importance for re-assessment of current and future urban drainage in coping with the changing urban floods induced by local and large-scale changes.

Spatial Data and Catchment Discretization for Assessment Coastal Urban Drainage Performance Using GIS and MIKE URBAN-SWMM

The urban drainage model requires spatial data and catchment discretization because of the complexity of system. Using integration of Geometric Information System (GIS) technology and urban storm water models, the performance of urban drainage system can be analysed.[1] Especially in coastal area, the main problem of urban drainage is overloaded capacity because of rapid urbanization and coastal floods caused by storm surges and wave action superimposed on high water levels generated during the cycle of tides. Land use change, watershed area as settlements area, clogged drainage pipe/channel, the changing of imperviousness of land cover also contributes to large volume of surface runoff. Moreover, the developments can change land cover in urban area and increasing rainfall runoff. One of the solutions for coastal urban drainage is by using polder system for flood control. The purpose of this paper is to illustrated how GIS can model the catchment discretization and MIKE URBAN-SWMM (Storm Water Management Model) can analyse water balance based on the rainfall return period of 25, 50 and 100 years. The research shows evaluation result of the polder performance including inundation depth and pump performance by linking GIS between storm water models. The case study is analysing the Pluit polder in Jakarta-Indonesia, which is connected to the Indonesia Central Bank compartment. Based on the model, this polder system can reduce flooding in Indonesia Central Bank Compartment up to 50%, however the inundation is still occurred.

POOR FLEXURAL REINFORCEMENT PLACEMENT FACTOR ON THE PERFORMANCE OF CONSTRUCTED DRAINAGE SYSTEM.

22Dec 2018 POOR FLEXURAL REINFORCEMENT PLACEMENT FACTOR ON THE PERFORMANCE OF CONSTRUCTED DRAINAGE SYSTEM. Kachalla Mohammed. Civil and Water Resources Engineering Department, University of Maiduguri, N.E. Nigeria.

Subsurface Drainage System Performance, Soil Salinization Risk, and Shallow Groundwater Dynamic Under Irrigation Practice in an Arid Land

In recent years, several arid lands have faced the major challenge of increasing risk of soil salinity caused by improper irrigation and drainage practices. Evaluating the relationship between soil salinity, drainage, and irrigation is therefore essential for understanding how to sustain the use of salinized soils in these lands. In this study, subsurface drainage performance, soil salinization risk, and shallow groundwater dynamic were evaluated under irrigation practice in a Tunisian arid land during two successive cropping years (2012–2013 and 2013–2014). Special attention was paid to the effect of subsurface drainage system on soil desalinization. Based on the analysis of the collected data, the following results were found: (1) frequent irrigation was a major factor in the rapid rise of shallow groundwater above critical soil depths; (2) inferior irrigation scheduling (i.e. large irrigation interval of 16–42 days) was the main cause of high soil salinization $$(\hbox {EC}_{\mathrm{e}})$$ around crop roots $$(\hbox {EC}_{\mathrm{e}} > 4\hbox { dS m}^{-1})$$ ; (3) the installed subsurface drainage system in the studied area (i.e. perforated corrugated pipe at a soil depth of 1.5 m) resulted in a substantial soil desalinization rate from the first to the second studied year, the average decrease in $$\hbox {EC}_{\mathrm{e}}$$ was 23.3%; (4) the drainage system was unable to drain more than 27% of the salt introduced by the irrigation water due to the clogging of the gravel filter by sand. These results may provide a reference for appropriate restoration in the studied area and in other arid farmlands with similar condition.

The performance and behavior of land drainage systems and their impact on field scale hydrology in an increasingly volatile climate

Escalations in rainfall intensity, both in terms of volume and frequency are increasing the volatility associated with grassland agriculture on poorly drained soils. The principal mechanism of reducing this volatility is by means of land drainage; however the efficacy of drainage systems is widely variable and has not been fully quantified. The excavation of soil test pits and a corresponding examination of the soil profile enables bespoke land drainage system design. Across heterogeneous soil-scapes this leads to variations to both groundwater and shallow drainage designs. In the present study we examine the performances of 9 site-specific drainage systems (5 groundwater and 4 shallow drainage designs), during a high rainfall period (01/10/2015–31/05/2016) in terms of response times (start, peak and lag times), discharge characteristics (peak flow rate, total discharge, flashiness index, discharge hydrographs) and water table control capacity. Response times were not affected by drainage system or drainage design type, showing similar responses despite variation in soil types where appropriate drainage systems are installed. Total discharge (1098.4 vs. 189.6 m3/ha) and peak flow rate (51.0 vs. 16.8 m3/ha/h) were significantly higher in groundwater designs relative to shallow alternatives. Groundwater drainage designs generally maintained a deeper mean water table depth (0.82 m) than shallow designs (0.53 m) during the study period. The functional capacity of each land drainage system was inherently different. The comparison of such systems highlights contrasting behaviors of individual drainage systems and drainage design types, which is dictated largely by the hydraulic capacity of the soil within their catchment and their connectivity to different water bodies (groundwater versus perched water). All systems reduced the overall period of waterlogging and improved the conditions for both the production and utilization of the grasslands they drain, although temporal variations in agronomic parameters are likely to be more pronounced in shallow designs.

Projected Changes of Precipitation IDF Curves for Short Duration under Climate Change in Central Vietnam

In future years, extreme weather events are expected to frequently increase due to climate change, especially in the combination of climate change and events of El Niño–Southern Oscillation. This pays special attention to the construction of intensity–duration–frequency (IDF) curves at a tempo-spatial scale of sub-daily and sub-grid under a context of climate change. The reason for this is that IDF curves represent essential means to study effects on the performance of drainage systems, damps, dikes and reservoirs. Therefore, the objective of this study is to present an approach to construct future IDF curves with high temporo-spatial resolutions under climate change in central Vietnam, using the case of VuGia-ThuBon. The climate data of historical and future from a regional climate model RegCM4 forced by three global models MPI-ESM-MR, IPSL-CM5A-LR and ICHEC-EC-EARTH are used to re-grid the resolution of 10 km × 10 km grid spacing from 25 km × 25 km on the base of bilinear interpolation. A bias correction method is then applied to the finest resolution of a hydrostatic climate model for an ensemble of simulations. Furthermore, the IDF curves for short durations of precipitation are constructed for the historical climate and future climates under two representative concentration pathway (RCP) scenarios, RCP4.5 and RCP8.5, based on terms of correlation factors. The major findings show that the projected precipitation changes are expected to significantly increase by about 10 to 30% under the scenarios of RCP4.5 and RCP8.5. The projected changes of a maximum of 1-, 2-, and 3-days precipitation are expected to increase by about 30–300 mm/day. More importantly, for all return periods (i.e., 10, 20, 50, 100, and 200 years), IDF curves completely constructed for short durations of precipitation at sub-daily show an increase in intensities for the RCP4.5 and RCP8.5 scenarios.

A-35 高層建物のループ通気方式の排水能力の把握と予測手法に関する研究 : その4. ループ通気管多数箇所設置方式の検討

A-35 高層建物のループ通気方式の排水能力の把握と予測手法に関する研究 : その4. ループ通気管多数箇所設置方式の検討

A-34 高層建物のループ通気方式の排水能力の把握と予測手法に関する研究 : その3. ループ通気管2箇所設置方式の検討

A-34 高層建物のループ通気方式の排水能力の把握と予測手法に関する研究 : その3. ループ通気管2箇所設置方式の検討

A-29 通気弁排水システムの排水能力評価に関する研究 : (第1報) 排水横枝管通気における正圧発生防止手法の検討

A-29 通気弁排水システムの排水能力評価に関する研究 : (第1報) 排水横枝管通気における正圧発生防止手法の検討

Seismic in-Soil Isolation of Solid Waste Landfill Using Geosynthetic Liners: Shaking Table Modeling of Tehran Landfill

Seismic loads may damage municipal solid waste (MSW) landfills through the relative movements within the landfill system. These movements can disrupt performance of drainage and gas collection systems, thereby resulting in environmental pollution. The smooth synthetic materials might be placed beneath the structures to provide seismic protection by absorbing the imparted energy of earthquakes through the sliding mechanism. It has been found that a high strength geomembrane placed over the other smooth and lubricated geomembrane sheets constitutes an efficient seismic liner. In the present study, experimental investigations were conducted to evaluate role of in-soil base isolation on seismic response of the Tehran MSW landfill. Results of geophysical and geotechnical investigations in the landfill site are presented in detail. Shaking table tests were conducted on the MSW embankment isolated by semi-elliptic shaped liners and subjected to harmonic sinusoidal base excitations. The results for the isolated and non-isolated cases are compared in terms of permanent displacement and seismic response. It has been observed that at all elevations the spectral accelerations within the waste decreased by base isolation, especially for the more intense excitations. Results of the present study demonstrate a suitable application of geosynthetic liners for seismic retrofitting of landfills.

Numerical Study of the Effects of Drainage Systems on Saturated/Unsaturated Seepage and Stability of Tailings Dams

The stability of tailings dams is affected by seepage characteristics such as the location of the phreatic surface inside the dam, the effects of the capillary fringe, and the unsaturated zone above the zero pore pressure level. In this study, the performance of drainage systems in tailings dams was investigated by analyzing saturated and unsaturated seepage in the dam, considering the effects of the construction method, tailings properties, and the type of drainage systems. First, general seepage characteristics in tailings dams were studied and the effects of non-homogeneity were investigated. Our results show that in a silty tailings dam with a height of 15 m, unsaturated plus capillary seepage flux can reach 13% of the total seepage. The total head vs. discharge volume curves under various conditions were compared and their practical implications are presented. Then, stability analyses were carried out using the results of seepage analyses for different construction methods, material properties, and drainage systems. Finally, a number of practical conclusions are drawn regarding dam stability and the efficiency of toe, blanket, and chimney drains in different construction methods. Using a blanket and/or a chimney drain can increase the stability safety factor by up to two times, depending on the type of material.

Partitioning the impacts of spatial and climatological rainfall variability in urban drainage modeling

Abstract. The performance of urban drainage systems is typically examined using hydrological and hydrodynamic models where rainfall input is uniformly distributed, i.e., derived from a single or very few rain gauges. When models are fed with a single uniformly distributed rainfall realization, the response of the urban drainage system to the rainfall variability remains unexplored. The goal of this study was to understand how climate variability and spatial rainfall variability, jointly or individually considered, affect the response of a calibrated hydrodynamic urban drainage model. A stochastic spatially distributed rainfall generator (STREAP – Space-Time Realizations of Areal Precipitation) was used to simulate many realizations of rainfall for a 30-year period, accounting for both climate variability and spatial rainfall variability. The generated rainfall ensemble was used as input into a calibrated hydrodynamic model (EPA SWMM – the US EPA's Storm Water Management Model) to simulate surface runoff and channel flow in a small urban catchment in the city of Lucerne, Switzerland. The variability of peak flows in response to rainfall of different return periods was evaluated at three different locations in the urban drainage network and partitioned among its sources. The main contribution to the total flow variability was found to originate from the natural climate variability (on average over 74 %). In addition, the relative contribution of the spatial rainfall variability to the total flow variability was found to increase with longer return periods. This suggests that while the use of spatially distributed rainfall data can supply valuable information for sewer network design (typically based on rainfall with return periods from 5 to 15 years), there is a more pronounced relevance when conducting flood risk assessments for larger return periods. The results show the importance of using multiple distributed rainfall realizations in urban hydrology studies to capture the total flow variability in the response of the urban drainage systems to heavy rainfall events.

Developing Intensity–Duration–Frequency (IDF) Curves under Climate Change Uncertainty: The Case of Bangkok, Thailand

The magnitude and frequency of hydrological events are expected to increase in coming years due to climate change in megacities of Asia. Intensity–Duration–Frequency (IDF) curves represent essential means to study effects on the performance of drainage systems. Therefore, the need for updating IDF curves comes from the necessity to gain better understanding of climate change effects. The present paper explores an approach based on spatial downscaling-temporal disaggregation method (DDM) to develop future IDFs using stochastic weather generator, Long Ashton Research Station Weather Generator (LARS-WG) and the rainfall disaggregation tool, Hyetos. The work was carried out for the case of Bangkok, Thailand. The application of LARS-WG to project extreme rainfalls showed promising results and nine global climate models (GCMs) were used to estimate changes in IDF characteristics for future time periods of 2011–2030 and 2046–2065 under climate change scenarios. The IDFs derived from this approach were corrected using higher order equation to mitigate biases. IDFs from all GCMs showed increasing intensities in the future for all return periods. The work presented demonstrates the potential of this approach in projecting future climate scenarios for urban catchment where long term hourly rainfall data are not readily available.

Regional Climate Change and Drainage Systems: Effects on Corn Productivity and Profitability in Campinas, Brazil

Abstract. Many natural systems are being affected by regional climate change. Regional climate change may affect the profitability and productivity of corn, which may require changes in the optimum design of drainage systems in the future. Our aim is to determine the effects of regional climate change on the relationship between drain spacing, corn productivity, and profitability and to derive estimates of productivity and profitability until the year 2100 using different future scenarios of climate simulation (CNTRL, HIGH, LOW, and MIDI). Our goal is to optimize drainage system designs that account for changes in climate using different drain spacing and types of soil in Campinas, Brazil. This study also evaluates the performance of the Eta regional climate model to simulate precipitation and air temperature for the study area. Evapotranspiration calculated with the Thornthwaite method (using observed and simulated data) and precipitation data were used as input for the SISDRENA model, which evaluates the performance of one-dimensional drainage systems. As output, the SISDRENA model provides information about drainage system design and indexes of water stress, productivity, and profitability. The general conclusion is that the Eta model is a good tool for studying the effects of climate change in the region because the simulations approximated the observed data. All sets of analyzed years indicated that a spacing of 20 m between drains was best, producing the highest average productivity and profitability. Clay loam soils tended to have higher productivity and profitability than clay soils, which translates to greater profit for the producer. However, the temperature and precipitation variations predicted by the Eta model showed that corn profitability may be reduced, changing the potential productivity in Campinas, Brazil.

A multi-objective optimization model to enhance the comprehensive performance of underground gas drainage system

The underground gas drainage system plays a vital role in the underground drilling drainage which is widely used in Chinese coal mines. However, the pure gas drainage flow, gas concentration and energy efficiency, which together represent the comprehensive performance of gas drainage system, are generally low due to the mismatching between the drainage system and drainage objects. The optimization of gas pipeline system has been extensively investigated, but fewer studies consider the diversity and temporal correlation of drainage object characteristics and the multi-objectives of drainage system.In this paper, a multi-objective optimization model, which fully considers the above factors, is built to achieve the match between the drainage system and drainage objects. Furthermore, the gas flow and methane transport model is established to calculate the values of multi-objectives and constraints. A derivative-free algorithm, bound optimization by quadratic approximation (BOBYQA), is proposed to solve the optimization model. Finally, the optimization model is applied to a typical modern coal mine and verified through the comparisons with field monitoring data and a recognized empirical formula. The optimization results reveal that (1) the variation trends of the three objectives with decision variables are different from each other, which indicates the optimal decision variables should be determined by considering all three objectives; (2) the optimization model can appropriately allocate the negative pressure in view of the interrelationship and different characteristics of drainage objects; (3) the decision variables can be adjusted to fit the characteristics change of drainage objects with time.

Climate change and soil wetness limitations for agriculture: Spatial risk assessment framework with application to Scotland

Waterlogged soils can act as a major constraint on agriculture by imposing limits on the use of machinery and stocking levels. Inappropriate use of waterlogged soils can cause serious damage to soil and water resources. Limitations are particularly pronounced in locations with wetter climates and on soils which have inherent drainage problems. Constraints may also vary temporally due to climate variability and climate change. These issues are investigated through the strategic use of a risk assessment framework that combines climatic and soil factors to map changes in soil wetness risk at country level. Wetness risk is evaluated in terms of soil wetness classes and the constraints it imposes on arable and improved grassland using an empirical land capability scheme. A case study in Scotland analyses spatio-temporal variations of wetness risk and associated land-use constraints for 1961–1980 and 1991–2010 periods and using a future 2050s projection based upon the HadRM3/HadCM3 climate model ensemble. Results suggest increased risk levels in recent decades for south-west and central Scotland which are both important areas for livestock agriculture. However, wetness risk in these high risk areas is tentatively projected to reduce under average 2050s conditions based upon a central estimate from the model ensemble. Wetness risk has been adjusted based upon the assumed presence and performance of subsurface field drainage systems but this remains a significant uncertainty due to limited data availability. As artificial drainage represents the major alternative adaptation strategy compared to change of land use, the case study highlights a need to further evaluate its efficacy and long-term viability for those areas identified at high risk.

The effect of submersion in the ochre formation in geotextile filters

This analyzes the effect of submersion in the formation of ochre biofilm in geotextile filters used in drainage systems. The chemical microbiological aspects involved in ochre formation and clogging of drainage systems are discussed. Clogging by ochre may be considered a major threat in the performance of filters and drainage systems. This process has been observed in the field and demonstrated in laboratory tests under well-controlled conditions. Oxygen is needed for ochre formation and is available at the water–air interface of the filters. If the filters are submerged, oxygen may also be available dissolved in the water, with higher concentrations close to the surface due to the diffusion process. Column filter tests with the introduction of iron bacteria under three different filter submersion conditions were carried out. Woven geotextile filters were used in all tests. Biofilm formation on the geotextile filters were evaluated through the analysis of EDS (Energy Dispersive X-ray detector) and scanning electron microscopy. Ochre formation was verified in all tests, confirming that ochre formation can occur even under submerged conditions. The formation of ochre biofilm decreased with the depth of the geotextile filter in relation to the water surface, following the expected reduction of available oxygen below the water surface.