Drainage Outlet Research Articles

Stormwater systems as a source of marine debris: a case study from the Mediterranean coast of Israel

Drainage (or stormwater) systems are a potential source of marine debris. Approximately 67 km (33%) of the land along the Mediterranean coast of Israel is considered urban, covered by concrete and asphalt. The purpose of the present pilot study was to determine the composition of the solid waste in a drainage system and evaluate to what extent municipal sources contribute to marine debris. We sampled the waste in Netanya, a medium-size city (245,000 residents) on the central Mediterranean coast of Israel. Samples were taken from seven street stormwater receptacles prior to the first significant rain and then on the beach near a drainage outlet, a few hours after this substantial rain. In terms of composition of the debris, paper, cigarette butts, and sanitary items made up a higher proportion of the drainage system debris than those items did on the beach. In contrast, single-use items, polystyrene pieces, bottle caps, and plastic drinking bottles composed more of the debris on the beaches compared to the debris in the drainage system. Overall, we found that municipal stormwater systems contribute significant amounts of solid waste to marine debris on Israeli beaches. Preventing the waste from reaching the streets might help reduce marine debris on the beaches, especially at the beginning of the rainy season. There are multiple solutions, but all will require creativity and resources and constant maintenance. Educating the public to prevent disposal of solid waste items in the street is also important as a way to reduce terrestrial as well as marine debris.

Subglacial discharge weakens the stability of the Ross Ice Shelf around the grounding line

In this paper, we examine potential impact of discharge in Subglacial Lake Engelhardt, West Antarctica, on the stability of the Ross Ice Shelf around the grounding line by combining satellite altimetry and remote sensing images. According to satellite altimetry data from the Ice, Cloud and Land Elevation Satellite (ICESat; 2003–06), Subglacial Lake Engelhardt (SLE) discharged ca. 1.91 ± 0.04 km3 of water into the downstream region. The ice-surface record derived from ICESat (2006–09) and CryoSat-2 (2011–17) data shows that the lake gained ca. 2.09 ± 0.05 km3 of water during the refilling event following the drainage event, taking three times as much time to reach the previous water level before the discharge; the calculation demonstrates that water input from an upstream lake is unable to sustain water increase in SLE, indicating that the subglacial, hydrologic system and groundwater flow could have contributed to water increase in SLE via hydrologic networks. Satellite images captured surface depressions and crevasses at the drainage outlet point of hydrologic networks around the grounding line; satellite altimetry data show that the ice surface there is still depressing even though the subglacial discharge has finished, potentially reflecting the long-term impact of subglacial discharge on the stability of the immediate Ross Ice Shelf around the grounding line.

Research on Design and Operation Method of Dewater and Filled System for Cushion Pool of High Dams ——Taking the project of BHT hydropower plant in China as an example

Dam is set in large hydropower station. Cushion pool is built behind the dam for the flood discharge and energy dissipation of the reservoir. Operation of flood discharge and energy dissipation for some time, Cushion pool is dewatering and structure safety of which is study, then cushion pool is filled. Temporary dewater and filled system is used by previous engineer, but is arranged and controlled hard. Based on need of the cushion pool dewatering and filling, for an example of Baihetan hydropower station, necessity and feasibility are study. Then a permanent dewatering and filling system is designed for cushion pool. Design principle and arrange method are described. Many technical difficulties are study and resolved such as effect of valley deformation on the control system of dewatering and filling, demand of dewatering and filling device parameter, performance quota formulate based on large water level amplitude, protective measures in the working condition of much silt on the downstream and humidity in the equipment room of the second-dam and project of dewater drainage outlet under the water. By gravity drainage and filling based on water level difference and pump drainage, much electric energy is saved and personnel operating environment and working conditions are improved.

Experimental Study of the Development of Soil Microstructure under the Electroosmosis Dewatering Process

Several laboratory experiments using scanning electron microscopy and mercury intrusion porosimetry were conducted to study the development of soil microstructure during electroosmosis dewatering process. The test results indicate that the moisture content in different treating areas shows remarkable temporal difference; the reasons could be attributed to the distance to the drainage outlets and the treatment duration. On a microscopic level, the affected pore sizes are mainly 0.01–1 and 1–10 μm, and their proportions start to vary when the moisture content reaches the liquid limit. The total volume for pores in anodic soil decreases nearly 50% after the first 20% of total drainage water is exported and is not linearly related to the amount of discharged water. The surface of the soils becomes smoother, and clay particle connection changes from edge‐to‐edge to face‐to‐face. Pores are hard to be observed at the end of the process.

Accumulation of microcapsules derived from coated fertilizer in paddy fields

Japanese agriculture uses large amounts of plastics. Fertilizer-containing plastic microcapsules with a diameter of 2–5 mm (“coated fertilizer”) are not recovered after use, and after diffusion of the fertilizer components these microcapsules are found in large quantities, not only on agricultural land but also along the coast of Japan. Here, we investigated the accumulation of microcapsules derived from coated fertilizer in 19 paddy fields. Microcapsules were detected in all of the paddy fields surveyed, at concentrations in the range of 6–369 mg/kg (mean 144 mg/kg)—much higher than the concentrations of microplastics in farmlands in other countries. There was no difference in mean microcapsule concentration between sampling sites with continuous rice cultivation and those with crop rotation, but that of a paddy field that had never received coated fertilizer was significantly lower. Examination of the spatial distribution of microcapsules in one paddy field showed that there was a hot spot with a high concentration near the drainage outlet. This was likely due to the strong influence of irrigation water flowing from the water inlet to the drainage outlet. The amount of microcapsules accumulated in Japanese paddy fields, as estimated from our results, and the amount applied to the fields, as estimated from the statistics, were almost equivalent. Therefore, most of the microcapsules that have already been applied to paddy fields may continue to accumulate. The impact of these high concentrations of microcapsules on the soil environment needs to be assessed.

Controls Since the mid‐Pleistocene Transition on Sedimentation and Primary Productivity Downslope of Totten Glacier, East Antarctica

AbstractThe rapidly thinning Totten Glacier on the Sabrina Coast, East Antarctica, is the primary drainage outlet for ice within the Aurora Subglacial Basin, which could destabilize under the current atmospheric warming trend. There is growing need for direct geological evidence from the Sabrina Coast to frame late twentieth century Totten melting in the context of past warm climate analogs. Addressing this need, sediment archives were recovered from two sites on the Sabrina Coast slope and rise that record changes in terrigenous sedimentation and primary productivity in the region over glacial cycles since the mid‐Pleistocene transition (MPT). This research presents physical properties, grain size, diatom abundance and assemblages, and geochemical analysis from the two sites to determine how the processes that control sedimentation change between glacial and interglacial phases. The stratigraphic sequences in both cores record cyclic variations in physical properties and diatom abundances, which radiocarbon and biostratigraphic chronologies reveal as 100 Kyr glacial‐interglacial cyclicity. During glacials, terrigenous sediment deposition is enhanced by advanced grounded ice on the shelf, while primary productivity is restricted due to permanent summer sea ice extending past the continental slope. During interglacials, pelagic sedimentation suggests high surface productivity associated with contractions of regional sea ice cover. Comparison with post‐MPT slope records from Wilkes Land and the Amundsen Sea shows that this pattern is consistent in slope sediments around the margin. The higher‐amplitude variations in Antarctic ice volume and sea ice extent post‐MPT ensure that these signals are pervasive around the Antarctic margin.

Geochemical methods for mapping available-Si distribution in soils in West Sumatra, Indonesia

Silicon (Si) is an important element for rice plant, and its availability in soil is an important factor affecting sustainable rice production. Herein, the distribution of available Si and its correlation with land-use type and soil-erosion status were investigated and discussed using the universal soil loss equation (USLE) in the Sumani watershed (SW). This watershed is the main rice-production area in Sumatra, Indonesia. Results showed that the available Si levels in sawah soil were less than 300 mg SiO2 kg−1 on average. Sawah means a leveled and bounded rice field with an inlet and an outlet for irrigation and drainage, respectively. Available Si content in river sediments was also studied and determined to be higher than those in sawah or other land-use types. This finding may indicate that available Si or soil rich in Si was redistributed through soil erosion. Soil-erosion rate was negatively correlated with the concentration of available Si in soils. Land-use types with smaller values of crop factor in USLE calculation and soil with lower pH showed relatively lower available Si in the soils. Overall, our findings indicated that soil erosion and land-use types affected the distribution of available Si in the watershed.

Response of palladium in receiving water bodies to rainfall-runoff.

Palladium (Pd) is widely used in automotive catalytic converters to reduce toxic gas emissions. The input of Pd in the rainfall-runoff is an important contributing factor to the accumulation of Pd in receiving water bodies. In this study, the Meishe River in Haikou, Hainan Province, China, was used as the research area, and palladium (Pd) was selected as the target pollutant. This study explored the response of Pd in the receiving water body to rainfall-runoff and to analyze the influencing factors. The results showed that the dissolved Pd concentration in the receiving water body had a corresponding relationship with that in rainfall-runoff. The response of suspended Pd in the receiving water body to rainfall-runoff was closely related to the location of the drainage outlet. Compared with that of suspended Pd, the response of dissolved Pd in the receiving water body to that in the rainfall-runoff was more obvious. Seven meters downstream from the outfall was the most sensitive response distance of dissolved Pd in receiving water bodies to rainfall-runoff, and the response time was approximately 0-10min. The suspended Pd at 3m downstream from the outfall also had a certain response to the rainfall-runoff, and the response time was approximately 15-25min. The response time of the suspended Pd in the receiving water body depended largely on the first flush ability of the runoff. There was a moderately positive correlation between the dissolved Pd and Cl- in the receiving water body (r = 0.687; p < 0.05). The effects of pH, Eh, and total suspended solids (TSS) on suspended Pd were reduced in the response process of the receiving water body. The synergistic effect of multiple factors increased the uncertainty of the Pd response.

Spatial and temporal variability in discharge and nitrate in Iowa subsurface drains.

Agricultural subsurface drainage can be an important conduit of nitrate from agricultural fields to streams. This study focused on understanding the variability in nitrate concentrations and loads, exported by subsurface drains, into a small, north-central Iowa stream. Ninety-three subsurface drains in this watershed were sampled up to 5 times between 2006 and 2008. Additionally, 2 subsurface drains and the stream draining the study area (South Fork Iowa River near Blairsburg, IA, USA) were sampled frequently during the growing seasons in 2007 and 2008. Spatial variability analysis revealed no distinct spatial pattern in nitrate concentrations. The median nitrate concentrations were not significantly different when the drain outlets were characterized by diameter (17-23 cm, 27-48 cm, 60-108 cm). The eight large subsurface drains (part of the public drainage network) had less variability in nitrate concentration than the smaller drain sizes and generally contributed 70-87% of the total water and nitrate loads exported by subsurface drains to the stream. During high-discharge events, the medium-sized (27-48 cm) subsurface drains discharging to the stream became more important by contributing a higher discharge and nitrate load. The temporal variability examined in this study found that discharge and nitrate loads were influenced by the amount of precipitation that had occurred over the previous months. This paper demonstrates the spatial and within-season homogeneity of nitrate delivery to a stream from an intensely agricultural landscape that has subsurface drainage.

Impact of Escherichia coli from stormwater drainage on recreational water quality: an integrated monitoring and modelling of urban catchment, pipes and lake

In recent years, recreational waterbodies are increasingly favoured in urban areas. In spite of the growing concerns for maintaining the required bathing water quality, the impacts of stormwater drainage are still poorly controlled. In this context, this study originally develops an integrated urban catchment-pipes-lake monitoring and modelling approach to simulate the impacts of microbial quality from stormwater drainage on recreational water quality. The modelling system consists of three separated components: the urban catchment component, the 3D lake hydrodynamic component and the 3D lake water quality component. A series of processes are simulated in the model, such as rainfall-discharge, build-up, wash-off of Escherichia coli (E. coli) on urban surfaces, sewer flows, hydrothermal dynamics of lake water and transport and mortality of E. coli in the lake. This integrated model is tested for an urban catchment and its related recreational lake located in the Great Paris region. Continuous monitoring and samplings were performed at the stormwater drainage outlet and three different sites in the lake. Comparing the measured data with simulation results over 20 months, the modelling system can correctly represent the E. coli dynamics in the stormwater sewer systems and in the lake. Although uncertainties related to parameter values, pollution sources and E. coli mortality processes could be further discussed, the good performance of this modelling approach emphasizes a promising potential for urban bathing water quality management.

Sediment removal from dam reservoirs using syphon suction action

Dam reservoir siltation is a worldwide problem that results in loss of storage capacity and blockage of drainage outlets. Previous sediment removal techniques include flushing, excavation, dredging, and sluicing. In this study, sediment removal is investigated experimentally using image processing techniques, to assess the suction action of a syphon pipe. The syphon results in a scour hole that depends on several factors including the sediment mean diameter (d50), the applied suction head (Hw), the pipe diameter (dp), and the penetration depth (Zo). One soil type was used, poorly graded sand (d50 of 1 mm), to examine the interdependence of the other factors on the developed scour hole at equilibrium. Three heads (Hw) of 0.82 m, 1.04 m, and 1.22 m were applied and three pipe diameters (dp) of 6 mm, 9.5 mm, and 13.8 mm were used. Various Zo values that ranged between 0.0 and 7.0 cm were used. Measurements of the hole depth (hd), the hole diameter (D), and the removed soil mass were recorded. Non-dimensional characteristic relationships between the different factors were developed and a new non-dimensional design parameter (ϕ) is proposed to be used for estimating the scour hole dimensions. The design parameter ϕ depends on (Zo/Hw) and Reynolds number as input parameters. The results indicate a linear relation between (D/dp) and (hd/dp) with a regression coefficient (R2) ≈ 0.98, and a power-law relation between the normalized weight of the removed sediments (Ws/Fp) and (hd/dp) with R2 ≈ 0.95, where Fp is the suction pressure force.

Sediment sources, soil loss rates and sediment yields in a Karst plateau catchment in Southwest China

Intensive agricultural activities have accelerated soil erosion and rocky desertification in karst regions of southwest China. Knowledge of sediment sources and soil erosion rates can be used to target soil conservation measures and to improve calibration and validation of process-based soil erosion and sediment delivery models for scenario analyses. Due to the complexity of karst environments, however, catchment scale information on these components of sediment budgets has rarely been assembled, meaning there continues to be an evidence gap. Within this context, this study selected Chenqi catchment, given its appropriate research infrastructure, to investigate sediment sources and soil loss rates in a typical karst agroforestry landscape. We estimated the relative contributions from three sources: surface soil, subsurface soil and clastic rock, using a composite fingerprinting procedure combining 137Cs and magnetic susceptibility and a frequentist un-mixing model with Monte Carlo uncertainty analysis. Suspended sediment samples were taken at an hourly interval during seven rainfall events in 2017–2018 to characterize and quantify the sediment exported in both surface and underground drainage. The overall average median contributions (with 5th-95th percentile uncertainty ranges) from the sources to the suspended sediment samples from the surface drainage outlet were in the order: 62% (0−99%) subsurface soils, 25% (0−91%) surface soils and 13% (0−45%) clastic rock. For the sediment samples collected from the underground drainage catchment outlet, the corresponding estimates were in the order: 68% (0−97%) subsurface soils, 25% (0−53%) clastic rock and 7% (0−44%) surface soils. Plot scale soil loss rates were highest on cropland (0.70 Mg km−2) and pasture land (0.48 Mg km−2). The average (2017 and 2018) annual suspended sediment load exported through the surface outlet was 4.64 Mg km−2 compared with 1.20 Mg km−2 through the underground outlet. The broader implications of this study are that subsurface and clastic rock sources represent a significant component of the catchment sediment budget, meaning erosion control measures targeting hillslope surface soils alone may have limited impact on suspended sediment export at landscape scale.

The historical background of the canal system in Calcutta, India, and its contribution to development

Due to Calcutta’s proximity to the sea and location on the east bank of the River Hooghly in India, it used to experience tidal influence through its canals. This prompted commerce and trading, and Calcutta became an important trading port. The city was also influenced by the River Bidyadhari, which runs parallel to Hooghly. These two rivers and their tributaries and distributaries provided unique opportunities for commerce to British colonisers. Tolly’s Nullah was excavated in 1778 to connect these two rivers. Interestingly, for even a decade after the introduction of the Eastern Bengal State Railway in the nineteenth century, water trafficking was the predominant mode of transport. The canal system also provided irrigation water during the tidal period by controlling lock gates at strategic locations. Drainage of Calcutta mostly gravitated eastwards to Kultigong of the Matla estuary system, which ultimately led to the River Bidyadhari. Since 1856, it had served as an outlet for the city drainage, which was supplemented by excavating new channels in 1928. This created a network of an organised ‘canal system’, which had sustained the city for centuries. The history of the development of this canal system, its lingering influence on the growth of Calcutta and its present status are summarised in this paper.

Water flow resistance along the pathway from the plow layer to the drainage canal via subsurface drainage in a paddy field

The functional decline of subsurface drainage systems has become a problem for the cultivation of upland crops in rotational paddy fields, necessitating the development of methods to determine its origin. This study aimed to quantify the water flow resistance (WFR) along the pathway from the plow layer to the drainage canal via aged subsurface drainage in a clayey paddy field. Hydrological monitoring was conducted in a clayey paddy field where subsurface drainage was installed over 20 years ago and soybeans were cultivated during the monitoring. The surface and subsurface drainage rates were measured using flowmeters attached to the drainage outlet. The water pressures along the pathway were measured using tensiometers or pressure transducers installed in the wells. Assuming continuous water flow through the pathway, the time evolution of the sectional WFR was determined from the measured total head gradient and the drainage discharge. Then, potential horizontal and vertical water flow rates, defined as the quotient of the maximum possible driving forces divided by the minimum WFR, were calculated. During rainfall events, the subsurface drainage rate increased rapidly after the start of the drainage, became high and nearly constant with time, and then gradually decreased. When the subsurface drainage rate was high, the total water head gradient in the vertical direction from the plow layer to the collecting drain was large, while the horizontal water head gradient in the plow layer was very small. The potential flow rates of the vertical and horizontal sections ranged from 2.1–5.7 mm/h, and from 6.2 to over 79 mm/h, respectively, indicating that the vertical WFR mainly determined the potential subsurface drainage rate. Our results suggest that simultaneous measurement of the pressure distribution along the water pathway and the subsurface drainage rate is a promising method for the diagnosis of aged subsurface drainage systems.

Prediction of the effects of management practices on discharge and mineral nitrogen yield from paddy fields under future climate using APEX-paddy model

This study is to evaluate the BMPs in the reduction of surface discharge and mineral nitrogen yield from paddy cultivation for three future time slices (e.g., the 2010s, 2040s, and 2070s) using APEX-Paddy (Agricultural Policy/Environmental eXtender-Paddy) model. The model was calibrated and validated for surface discharge and mineral nitrogen yield using 3-year monitoring data (2013–2015) from the conventional paddy management field (CMP-1). For surface discharge and mineral nitrogen yield estimates, the future projections of 29 GCMs (General Circulation Model) were bias-corrected and applied to the calibrated APEX-Paddy model. We investigated five specific management strategies related to paddy drainage outlet regulation and new fertilization methods, as the BMPs minimize the mineral nitrogen yield and surface discharges due to climate change. The modeling results indicated that the effects of BMPs would vary by future climate scenarios (i.e., RCP4.5, RCP8.5) and periods (i.e., the 2010s, 2040s, 2070s). It was generally expected that the surface discharge and mineral nitrogen yields would increase in the future. The combination of raising drainage outlets and soil test-based fertilization (DOR-STF) showed a substantial reduction in surface discharge in both scenarios (RCP4.5 and 8.5); the highest reduction rate was observed in the 2010s and was estimated at 21.9 % under RCP4.5. Soil test-based fertilization (STF) showed a substantial reduction in mineral nitrogen yield by 31.0 and 28.3 % during the 2010s under RCP8.5 and RCP4.5, respectively followed by DOR-STF, as compared to conventional management practice (CMP-1). However, the combination of drainage outlet raising, and fertilizer application before outlet weir installation (DOR-FABWI) management resulted in increased mineral nitrogen yield of up to 31.0 % under RCP4.5 and 36.7 % under RCP8.5. The study findings indicate that climate change will increase exports of mineral nitrogen from paddy fields. Nevertheless, appropriate BMPs may play a vital role in reducing the mineral nitrogen yields for the production of paddy rice in future climates, and these effects may vary according to future climate conditions.

Effect of Drought and Irrigation Management on Two Rice Mutants of Bangladesh

Drought stress is a major constraint to the sustainable production of of crops. Rice (Oryza sativa L.) is considered as a drought-sensitive crop species. The experiment was carried out to investigate the response of two rice mutants to drought condition and to develop appropriate irrigation management. Experiment was conducted at mini-lysimeter (1.5 m x 1.0 m x 0.28 m, having drainage outlet and rain-shed) at BINA, Mymensingh in Aman season (August to October, 2017) and Aus season (March to June, 2018) consecutively. The mutants used were N4/250/P-1(2) and N4/250/P-2(6)-26. The mutants were tested against four levels of drought stress. The imposed treatments were: Normal irrigation (3 days AWD), supplemental irrigation (ASM drops below 85%, throughout the growing season), irrigation at 0.85 ASM (up to booting stage) then irrigation at 0.60 PASM, irrigation at 0.85 ASM (throughout the growing season). Treatments were imposed after 3 weeks from transplanting. Experiment was laid out according to random complete block design (RCBD) with split-plot arrangements and three replications. The results showed that the mutants produced reasonable yield under stress condition compared to normal irrigation condition, which indicates their tolerance capacity under drought condition. Rice drought tolerance could help the country deal with the shortages in water that are facing Bangladesh farmers already.

Evaluation of the trophic state predicted from lab and Landsat data of western coastal water of Suez Bay, Egypt

This study aimed to compare the trophic status assessments of the western coastal waters of Suez Bay, Gulf of Suez, Egypt. The Trophic Index (TRIX) that depends on the lab-based water quality measurements of nutrients, chlorophyll-a (Chl-a) and dissolved oxygen, was compared with the Carlson trophic state index that integrates lab-based data such as NH4 or PO4 concentration with Landsat data and geographic information system (GIS) techniques. The physicochemical properties were determined, which indicated that Suez Bay was in an eutrophication state limited by both N and Si. It was suggested that the most influential activities be the industrial and domestic drains that raised the TRIX value to 5.59 with a mesotrophic state on average. Likewise, phosphorus trophic status mapping applying Carlson trophic state index showed high activity nearby drain outlets, especially at the Cabanon drain. The regression statistical model indicated a relationship between lab data of nutrients and band values extracted from Landsat images. Accordingly, the integration of remote sensing and GIS techniques with laboratory data is useful for predicting the state of water quality in the coastal areas with a single lab-based water quality parameter.

Sediment dispersal and redistributive processes in axial and transverse deep‐time source‐to‐sink systems of marine rift basins: Dampier Sub‐basin, Northwest Shelf, Australia

AbstractMorphological scaling relationships between source‐to‐sink segments have been widely explored in modern settings, however, deep‐time systems remain difficult to assess due to limited preservation of drainage basins and difficulty in quantifying complex processes that impact sediment dispersals. Integration of core, well‐logs and 3‐D seismic data across the Dampier Sub‐basin, Northwest Shelf of Australia, enables a complete deep‐time source‐to‐sink study from the footwall (Rankin Platform) catchment to the hanging wall (Kendrew Trough) depositional systems in a Jurassic late syn‐rift succession. Hydrological analysis identifies 24 drainage basins on the J50.0 (Tithonian) erosional surface, which are delimited into six drainage domains confined by NNE‐SSW trending grabens and their horsts, with drainage domain areas ranging between 29 and 156 km2. Drainage outlets of these drainage domains are well preserved along the Rankin Fault System scarp, with cross‐sectional areas ranging from 0.08 to 0.31 km2. Corresponding to the six drainage domains, sedimentological and geomorphological analysis identifies six transverse submarine fan complexes developing in the Kendrew Trough, ranging in areas from 43 to 193 km2. Seismic geomorphological analysis reveals over 90‐km‐long, slightly sinuous axial turbidity channels, developing in the lower topography of the Kendrew Trough which erodes toe parts of transverse submarine fan complexes. Positive scaling relationships exist between drainage outlet spacing and drainage basin length, and drainage outlet cross‐sectional area and drainage basin area, which indicates the geometry of drainage outlets can provide important constraints on source area dimensions in deep‐time source‐to‐sink studies. The broadly negative bias of fan area to drainage basin area ratios indicates net sediment losses in submarine fan complexes caused by axial turbidity current erosion. Source‐to‐sink sediment balance studies must be done with full evaluating of adjacent source‐to‐sink systems to delineate fans and their associated up‐dip drainages, to achieve an accurate tectonic and sedimentologic picture of deep‐time basins.

Study on Dispersion of Marine Pollutants from Islands in the Southern Section of Bohai Strait

Wu, Y.; Li, Q.; Liu, Y.; Xu, Y.; Wang, X., and Li, W., 2020. Study on dispersion of marine pollutants from islands in the southern section of Bohai Strait. In: Zheng, C.W.; Wang, Q.; Zhan, C., and Yang, S.B. (eds.), Air-Sea Interaction and Coastal Environments of the Maritime and Polar Silk Roads. Journal of Coastal Research, Special Issue No. 99, pp. 242–249. Coconut Creek (Florida), ISSN 0749-0208.The three-dimensional hydrodynamic model was established based on FVCOM, coupled with the Lagrangian particle tracking module to study the water exchange ability of 15 drain outlets of North and South Changshan Island. Meanwhile, the 30-day influence distance was introduced to quantify the water exchange ability. The drain outlets with a strong water exchange capacity are mainly located in the east of North and South Changshan Islands and the southwest corner of South Changshan Island, and those with a weak water exchange capacity are mainly located in the northwest corner of North Changshan Island, joint of South Changshan Island and the tombolo dyke and inside the Changdao Harbor. The 30-day influence range of the 15 drain outlets of North and South Changshan Islands is significantly affected by monsoon. East Asian monsoon accelerates the dispersion of the pollutants in the south sea areas of Bohai Strait.

Integrated systems of major drainage and minor drainage towards low impact development

Many studies have been conducting in providing urban floods solutions to reduce runoff water in various ways. In developing urban areas equipped with drainage systems, where the channel has full capacity and flooding in some urban areas. One of the problems that can be identified is the condition where drainage has a peak flow load at the same hour leading to the same meeting point, outlet, or discharge, resulting in an increase of peak flow. This paper give an approach to how to integrate the runoff capacity of flow from minor drainage to mayor drainage for anticipating a peak flow in a particular area. The most important result was when high rainfall intensity started in the first hour, it should be no obstacles until the flow from minor drainage flow through the outlet towards major drainage, in the four hours after rainfall, peak flow happens to flow through study area. In the analysis, it is known that the peak flood discharge period of 5-yr and 10-yr returns is one hour after the rainfall. Therefore this will not happen when the flow from the drainage outlet has a travel time of under one hour or after 3 hours after rainfall.