Discharge Load Research Articles

Application of the entropy model to estimate flow discharge and bed load transport in a large river

The amount of sediment bed load being carried by rivers significantly impacts the inherent development of the riverine systems in terms of hydrodynamic and morphodynamic changes. In this direction, acoustic Doppler current profiler velocity literature data collected at the Óbidos station in the Amazon River were applied to investigate bed-load transport using the Entropy method. First, the cross-sectional velocity distribution was estimated with that model for two scenarios of source data: (a) all surface velocities and (b) single surface velocity as the maximum surface velocity. The latter analysis was conducted with two different assumptions of the surface velocity distribution: parabolic and elliptic. The error percentage for estimation of the mean cross-sectional velocity and discharge was 2.08% based on considering all surface velocities and was 4.08% and 12.5% based on parabolic and elliptic scenarios, respectively. Next, the shear velocity and Shields mobility parameter were calculated for two scenarios. Finally, the dimensionless bed load transport rate was calculated based on a range of particle diameters. Applying the different equations for the dimensionless bed load transport rate based on various scenarios of surface velocity distributions, the results from the entropy method agreed with the experimental data in the literature. Overall, the current study highlighted the potential of the entropy model to estimate river discharge and bed load transport in large rivers relying only on surface velocity.

Hydrological and hydraulic drivers of microplastics in a rural river sourced from the UK's largest opencast coal mine.

Microplastics (MPs) are ubiquitous in river and freshwater ecosystems. However, the hydraulic and hydrological mechanisms that regulate the activation and emissions of MPs from both the land surface and subsurface into rivers are not well understood. This study aims to quantify the instream MP concentration and MP load in a remote headwater catchment river (Taff Bargoed, Wales, UK), which drains the UK's largest opencast coal mine (Ffos-y-fran), over a two-year period. Small fibers (< 1mm) composed of acrylic and polyester dominated the MPs found in the Taff Bargoed, while less commonly observed MP fragments were mostly composed of polysulfone. River MP concentrations ranged from 0.27 to 28.87MP/m³ (average: 14.60±10.31MP/m³), and MP load ranged one order of magnitude from 0.08 to 3.04MP/s (average: 1.42±0.81MP/s). Statistically significant relationships were found between MP concentration, the number of dry weather hours and river discharge, which indicated rainfall-runoff induced, source limited, dilution effects on instream MP concentration. A negligible relationship between MP load and river discharge was observed, which suggests that MP load variability was independent of flow conditions, dry weather hours, and the MP concentration in the Taff Bargoed. Significant positive relationships between MP concentration and instream total suspended solids were also observed, indicating that this may provide a useful proxy for estimating MP variation in the Taff Bargoed. No longitudinal variation in MP concentration over a 2km reach was observed, where differences in flow and drainage area were negligible, however, MP concentration increased by a factor of 2-4 downstream of an inflowing tributary, also sourced from the Ffos-y-fran coal mine. Overall, the results of this study provide evidence that mining activities can contribute MPs in rural and remote rivers, with their contribution being regulated by the hydraulic and hydrological processes in the catchment.

Method for determining the bed load discharge by the parameter of the average depth of the layer of moving materia

The object of the study in this paper is the dunes form of transport of bed load in the channels of lowland navigable rivers. An accurate assessment of the bed load discharge is important when considering river morphology, conducting dredging and river regulation works to ensure navigational conditions, as well as when designing various engineering structures. This paper analyzes modern methods for measuring bed load discharge based on dune parameters. Considering the identified shortcomings and limitations of existing measurement methods, a new method for measuring bed load discharge is proposed. A distinguishing feature of the proposed method is the use of the average depth of the layer of moving material when determining bed load discharge. This parameter is defined as the ratio of the area of the moving material to the length of the moving material layer. Essentially, the moving material consists of dunes identified after filtering out minor bottom protrusions. The advantage of this method lies in using of the average depth of the moving material layer, which allows for all the dunes identified in the longitudinal profile to be accounted for when calculating the bed load discharge. The use of areal dune characteristics also enables the determination of bed load discharge in rivers where the bottom relief consists of deficit dunes.To confirm the effectiveness of this method, a series of experiments were conducted in the Channel Laboratory of the State Hydrological Institute in hydraulic flumes with a movable sand bed. The channel bedforms consisted of three-dimensional dunes. The flow regime in the flume was adjusted to replicate conditions typical of lowland navigable rivers. The experiments confirmed that even with the complex three-dimensional structure of the channel bedforms, the proposed method is highly accurate compared to existing methods.

Analisa Pengaruh Main Pressure Tank Cellar dalam Proses Discharge Semen di MV. Cepat

Discharge activities on a cement vessel can’t be separated from the discharge pneumatic system, because the bulk cement contained in the cellar tank must be pressurized so that the cement turns into dust and can be unloaded into the land sillo. Failure of the pneumatic system will pose a risk of time delays and losses for the company because it can’t carry out load discharge activities. When the cement discharge activity takes place, there are many problems with the pneumatic system due to the decrease in wind pressure. The purpose of this study was to determine the factors, impacts and efforts made to analyze the effect of main pressure on the cellar tank in the cement discharge process to reduce the risk of delays in cement discharge activities. This study used descriptive qualitative method. Where is described and explained each problem with a detailed explanation. Data collection techniques with the method of observation, interviews with the chief officer and supported by the method of documentation. Damage to the pneumatic valve system causes reduced pressure in the cellar tank to be a factor in the decrease in main pressure. The impact of decreasing main pressure causes cement discharge activities to not be carried out optimally and can even hinder cement discharge activities. The conclusion obtained is that efforts need to be made to improve the skills of the crew on the operation of the pneumatic system and control, routines for the maintenance of the pneumatic system equipment according to the system maintenance plan.

Linkage detection between climate oscillations and water and sediment discharge of 10 rivers in Eastern China

Water discharge and sediment load are often controlled by a combination of factors. However, the relationship between water and sediment load changes and meteorological oscillations has rarely been explored for different river sizes. Explanations for the various responses of water-sediment changes to meteorological factors in different rivers is important for understanding global hydrology. In this study, we analyzed data from 2002-2022 using cross-wavelet and wavelet coherence in an attempt to characterize the effects of large-scale climatic oscillations on 10 rivers in eastern China. Comparing the results shows that water releases lag three months or more behind SST variations. It also oscillates interannually (mostly every 8-16 months). Most rivers runoff lags changes in PDO by three months or more. The impact of ENSO (El Niño-Southern Oscillation) on each river basin gradually decreases from south to north. The impacts on northern rivers such as the Yellow River, Huai Riverand Liao River are weaker. At the same time, the water discharge changes in the Pearl River and Minjiang River basins in southeastern China are extremely rapid and sensitive to ENSO events. Meanwhile, the impacts of ENSO on large rivers lasted throughout the study period, while the impacts of ENSO on smaller rivers had intermittent periods, and the response rates of geographically similar mountain and stream-type rivers were not the same. The effect of the PDO (Pacific Decadal Oscillation) warm and cold phases was different for each region. Our research contributes to understanding the relationship between rivers and climate oscillations, advancing Water-Sediment Balance and Global Sustainability—key goals of the United Nations 2030 Agenda for Sustainable Development.

Climatic and Anthropogenic Influences on Long-Term Discharge and Sediment Load Changes in the Second-Largest Peninsular Indian Catchment

In recent decades, understanding how climate variability and human activities drive long-term changes in river discharge and sediment load has become a crucial field of research in fluvial geomorphology, particularly for South Asia’s densely populated and environmentally sensitive regions. This study analyses spatio-temporal trends in water discharge (Qd) and sediment load (Qs) in the Krishna basin, Peninsular India’s second-largest catchment. Using nearly 50 years of daily discharge, sediment concentration, and rainfall data from the Central Water Commission (CWC) and India Meteorological Department (IMD), we applied Mann–Kendall, Pettitt tests, and double mass equations to detect long-term trends, abrupt changes, and the relative influence of climate and anthropogenic effects. Results showed a notable decline in the annual discharge, with 15 of 20 stations showing decreasing trends, especially along the Bhima, Ghataprabha, and lower Krishna rivers. The annual stream flow data showed a 53% decline in the mean Qd from 26.01 × 109 m3 year−1 before 2000 to 12.32 × 109 m3 year−1 after 2000 at the terminal station. Eight of ten gauging stations showed a significant decrease (p-value &lt; 0.05) in their annual sediment load, with a 76% reduction across the Krishna basin after its changepoint in 1983. The Pettitt test identified a statistically significant downward shift in discharge at seven stations. Double mass plots indicate that anthropogenic factors, such as large-scale reservoirs and water diversion, are the main contributors, accounting for 82.7% of sediment decline, with climatic factors contributing 17.1%. The combined trend analysis and double mass plots confirm these findings, underscoring the need for further study of human impacts on the basin’s hydro-geomorphology. This study offers a clear and robust approach to quantifying the relative effects of climate and human activities, providing a versatile framework that can enhance understanding in similar studies worldwide.

Wavelet analysis of discharge and sediment load for the Subarnarekha, Brahmani, and Mahanadi rivers of India

ABSTRACT This study aims to identify distinct small-scale temporary patterns between the river discharge and suspended sediment load for the main tropical rivers using continuous wavelet transform. Strong annual and irregular semi-annual variabilities, with few quarterly and interdecadal variabilities, are observed in river discharge and sediment load. The wavelet coherence reveals that the strongest in-phase coherence relationships exist between total suspended sediment and streamflow. The methodology for identifying the primary climate factors that integrate the partial wavelet coherence (PWC), multiple wavelet coherence (MWC), and quadruple wavelet coherence (QMWC) techniques is presented. The results show that the El-Nino/Southern Oscillation (ENSO) is the major regulator of streamflow followed by Indian Ocean Dipole (IOD) and Pacific Decadal Oscillation (PDO). The chosen rivers show a statistically significant ( p ≤ 0.05 ) descending trend in sediment load but no significant positive or negative trend in river discharge. This could be due to regional sediment storage and large-scale stream events affecting the sediment transport dynamics.

The Roles of Nutrient Loading and River Discharge on the Phytoplankton Dynamics in the Semi‐Enclosed Sea

AbstractUnderstanding spatiotemporal variations in phytoplankton biomass is crucial to the health of marine ecosystems. Therefore, the Finite Volume Community Ocean Model (FVCOM)‐based Ecological Model (Integrated Compartment Model) was implemented to assess nutrient and phytoplankton dynamics in the Bohai Sea from 2010 to 2019. From 2010 to 2013, dissolved inorganic nitrogen (DIN) and dissolved inorganic phosphorus (DIP) levels in the Bohai Sea were higher (∼0.400 and 0.030 mg/L, respectively) in nearshore areas compared to other years. During the summer and fall, the spatial distribution of the DIN/DIP ratio in the Bohai Sea exhibited a double‐core structure. Higher values (&gt;100) were primarily concentrated in the central region of the Liaodong Bay and south of the Central Basin near the Yellow River Estuary. Statistical analyses and numerical experiments revealed that increasing DIP loading from rivers had a greater effect on phytoplankton biomass in the Laizhou and Bohai Bays than increasing DIN loading. However, the phytoplankton biomass in the Liaodong Bay was strongly influenced by both increasing DIN and DIP loading from rivers. Notably, the increase in phytoplankton biomass resulting from increasing DIN loading exceeded that from increasing DIP loading by 17% in the Liaodong Bay. The reduction in river discharge weakened circulation at the river mouths, thereby partially retaining surface phytoplankton. This was more predominant in the nearshore areas of the Yellow River owing to the higher river discharge in August 2019. This study provides valuable insights for the management and conservation of marine ecosystems.

A Single Chamber Urea/Persulfate Fuel Cell: Optimization of Cathode to Use Peroxydisulfate Electron Acceptor

Environmental and energy issues draw considerable attentions in the modern society. One of the options to simultaneously solve these issues can be a wastewater fuel cell to recover energy during wastewater treatment. The urea oxidation reaction (UOR) has been tackled to enhance the energy efficiency of electrochemical hydrogen production and/or fuel cell utilizing urea, an abundant nitrogenous pollutant in human (livestock) wastes, as an electron donor. In spite of the significant progresses on a direct urea fuel cell (DUFC), various problems were reported for real wastewater, in relation to the membrane fouling to hamper practical applications from urine. To this end, this study proposes a single chamber DUFC employing Ni-Cl as an anode, CuO/CN as a cathode, and peroxydisulfate (PDS) as an electron accepter. An ideal utilization of PDS should increase the open circuit voltage than O2, while catalytically activated PDS can eliminate aqueous pollutants (including urea) for urine treatment. The Ni-Cl anode was prepared by a simple HCl etching of Ni foam, enhancing the UOR activity compared to the mother foam. The CuO/CN cathode was prepared by a sequential electrodeposition and hydrothermal treatment. This presentation focuses on an enhanced catalytic activity of direct/indirect PDS reduction on the Ni-Cl and CuO/CN, as confirmed by cyclic voltammetry and constant load discharge of a single chamber urea/PDS fuel cell. In particular, this study interrogated the mechanism of urea oxidation in the single-chamber DUFC in comparison with a chemical PDS activation system. A proto-type single chamber fuel cell marked a maximum power density of 1.8 mW cm-2 with 0.3 M urea, to open a new era of urine fuel cell without usage of membrane and precious element catalysts.

Discharge and sediment load modeling using rating curve-based missing data management

ABSTRACT Hydrological models are vital for water management to determine in-stream flow, irrigational water, domestic water supply, and biodiversity conservation. This study formulates a hydrological model with a novel approach for streamflow and sediment load in the QGIS-supported Soil and Water Assessment Tool for the Halda River catchment, a unique ecological habitat for natural carp spawning and freshwater sources. The daily simulation uses an innovative stage–discharge relationship technique from available 15-day interval flow data. The model evaluation parameters R2 values 0.80 and 0.62, and NS values 0.81 and 0.61 for calibration and validation of streamflow suggested excellent agreement in the seasonal cycle and most of the monsoon peak flow. The streamflow/precipitation ratio indicates a significant influence of groundwater through infiltration. The baseflow shows a decreasing trend. The sediment load based on suspended sediment concentration at a downstream location is 1,625 tons/day. On the contrary, the model prediction is 30 times lower. The scattered sediment load data support the model estimate by considering relatively lower intervention or land use change in its upstream. This model provides a baseline for daily flow and sediment load for scenario modeling (e.g., climate change, land use change) for environmental flow estimation of the fish habitat, freshwater supply, irrigation, and salinity intrusion.

Tracing nitrogen and phosphorus pollution in urban runoff: Insights from isotopic tracers and SWMM modeling

Water contamination in certain rivers during rainfall necessitates the evaluation of pollutant levels within pipelines and the identification of their sources to ensure effective pollution control. In this study, we assess pollutant concentrations during runoff from surfaces, pipelines, and channels, identify pollutant sources within pipelines, and analyze sewage leakage contributions to channel pollution in residential areas in Wuxi City, China. The results showed that the event mean concentrations of total nitrogen (TN), total phosphorus (TP), ammonium (NH4+-N), and nitrate (NO3−-N) in the drainage outlet runoff were 3.4, 1.1, 8.8, and 14.9 times higher than in impervious surface runoff. The predominant forms of nitrogen and phosphorus in runoff shift from organic to inorganic as they move from the surface to pipelines. The pipeline load and contribution were further estimated by combining water quantity calculations from the calibrated and verified Storm Water Management Model (SWMM) with measured nitrogen and phosphorus concentrations in the runoff. TN, NH4+-N, NO3−-N, and PO43--P within the pipelines accounted for 59%, 83%, 90%, and 77% of the discharge loads, respectively. The application of the Stable Isotope Analysis in R (SIAR) package (MixSIAR) revealed that the domestic sewage and soil organic N were the predominant sources of pollutants within drainage pipelines, contributing 23.7% and 32.6% of NO3−-N, respectively. Additionally, the sewage leakage accounted for 33.7% and 66.9% of NO3−-N in drainage runoff and channels, respectively. Unlike existing methods, this study quantitatively highlights the significant impact of pipeline pollutants and sewage leakage on urban river water quality, providing essential insights for developing effective strategies to mitigate non-point source water pollution.

Runoff and sediment effect of the soil-water conservation measures in a typical river basin of the Loess Plateau

Soil erosion and sediment transport processes, which are intimately connected with hydrological processes, strongly affect land surface morphology and earth system dynamics. Over the past 60 years, intensive Soil-Water Conservation (SWC) measures implemented on the Loess Plateau have significantly reduced sediment load and concurrently exacerbated runoff declines, while the quantitative evaluation of the effects of SWC measures remains challenging. This study develops a sediment module which simulates the hillslope and in-stream sediment processes, and then incorporates the module into a Geomorphology-Based Ecohydrological Model (GBEHM). Besides, the model also couples with an explicit representation of different types of SWC measures, including both Hillslope SWC (HSWC) and River-network SWC (RSWC) measures. The newly developed hydro-sediment model is then applied to the Kuye River basin, a typical river basin on the Loess Plateau, and used for quantifying the effects of SWC measures on river discharge and sediment load during 1982–2019. Compared with Period 1 (1982–2000), the river discharge decreased by 48.7% in Period 2 (2001–2019), while the sediment load experienced a more substantial decrease of 95.3% between the two periods. Based on the numerical experiment results, HSWC and RSWC contributed to 25.4% (58 million m3/yr) and 28.9% (66 million m3/yr) of the annual runoff decline, as well as 58.1% (36 million t/yr) and 33.9% (21 million t/yr) of the annual sediment load reduction between the two periods, respectively. Besides, HSWC plays an increasingly important role in sediment reduction in recent years due to check dam silting. The model developed in this research is useful to evaluate the multi-faceted effects of existing SWC measures and to help with future SWC planning and policymaking.

Design and Construction of an Automatic Discharge and Sediment Load Monitoring Equipment

Design and Construction of an Automatic Discharge and Sediment Load Monitoring Equipment

Microscopic Insights into the Anomalous Heat Effect that Unify Disparate Experimental Results

The anomalous heat effect (AHE) has many embodiments including hydrogen loading by electrolysis, high and low hydrogen pressure over elevated temperature nanostructures, ultrasound, and glow discharge loading. The AHE was triggered by variable charging current, temperature fluctuations, high voltage pulses, laser pulses, ultrasound, and electrolysis time. Pd materials for which the AHE has been reported include wires, cylinders, foils, and nanoparticles. Ni materials for which the AHE has been reported include constantan wires, Ni in zeolites, and Ni nanostructures. It is highly likely that the same AHE mechanism underlies all these embodiments despite their seemingly wide differences. Many investigators involved in research on the anomalous heat effect (AHE), including this author, are of the opinion that phonons in Pd and Ni play a role in generating and sustaining the AHE. Here it is hypothesized that the AHE requires a specific frequency optical phonon resonance that couples to electromagnetic radiation of the same frequency. If it can be arranged to sustain this specific, resonance, then the AHE is produced. It is demonstrated how this one assumption, coupled to several recent experimental results, can lead to useful microscopic insights that unify disparate experimental results under one umbrella and that may also be useful to guide further experiments.

Water, Salt, and Ion Transport and Its Response to Water-Saving Irrigation in the Hetao Irrigation District Based on the SWAT-Salt Model

Soil salinization is one of the main hazards affecting the sustainable development of agriculture in the Hetao Irrigation District (HID) of Inner Mongolia. To grasp the water and salt transport patterns and spatial–temporal distribution characteristics of the HID at the regional scale, the improved Soil and Water Assessment Tool with a salinity module (SWAT-Salt) model was used to establish the distributed water and salt transport model for the watershed in this study. The results demonstrated that the modified model could more accurately represent the process of water and salt changes in the HID. The coefficient of determination (R2) in the simulation of streamflow and discharge salt loading was 0.83 and 0.86, respectively, and the Nash–Sutcliffe efficiency (NSE) was 0.80 and 0.74, respectively. Based on this, different hydrological processes (surface runoff, lateral flow, groundwater, soil seepage) as well as spatial–temporal distribution characteristics of water salinity in groundwater and soil were analyzed in the HID. Differences in groundwater and soil salinity in different land uses and soil types were also compared. Of these, surface runoff and lateral flow salt discharge loading are concentrated in the southwestern portion of the basin, while groundwater salt discharge loading is concentrated in the eastern as well as southwestern portions of the basin. The salt discharge loading from groundwater accounts for about 98.7% of the total salt discharge loading from all hydrological pathways and is the major contributing part of salt discharge from the irrigation area. Soil salinity increases gradually from west to east. Groundwater salinity (2946 mg/L) and soil water electrical conductivity (0.309 dS/m) were minimized in the cropland. Meanwhile, rational allocation of irrigation water can appropriately increase the amount of salt discharge loading. In conclusion, the model could provide a reference for the investigation of soil salinization and water–salt management measures in irrigation areas.

Optimized operation strategy for energy storage charging piles based on multi-strategy hybrid improved Harris hawk algorithm

In response to the issues arising from the disordered charging and discharging behavior of electric vehicle energy storage Charging piles, as well as the dynamic characteristics of electric vehicles, we have developed an ordered charging and discharging optimization scheduling strategy for energy storage Charging piles considering time-of-use electricity prices. The decision variables include the charging and discharging prices, states, and power of electric vehicles. We have constructed a mathematical model for electric vehicle charging and discharging scheduling with the optimization objectives of minimizing the charging and discharging costs of electric vehicles and maximizing the revenue of Charging piles. To address the challenges of multivariable, multi-objective, and high-dimensional optimization in the proposed model, we propose a Multi-strategy Hybrid Improved Harris Hawk Algorithm (MHIHHO). In addition, to validate the optimization performance of the proposed algorithm, CEC benchmark test functions are employed to assess the algorithm's optimization accuracy, convergence speed, stability, and significance. Finally, optimization-based scheduling simulations are performed considering power constraints for energy storage charging and discharging at different time intervals, as well as discharge loads. The proposed method reduces the peak-to-valley ratio of typical loads by 52.8 % compared to the original algorithm, effectively allocates charging piles to store electric power resources during off-peak periods, reduces user charging costs by 16.83 %–26.3 %, and increases Charging pile revenue.

Spatial assessment of pollutant loads for surface water quality management: a case study in Lai Chau city, Vietnam

The aim of this study is to present a method for estimating the pollutant load from different sources in an effort to provide improved information regarding water pollution and help control the surface water pollution, using Lai Chau city as a case study. The pollutant load was calculated in accordance with the Vietnam Environment Administration Decree No.154/2019 on the guidance for calculating the total pollutant load of river water. The pollutant sources include point sources (domestic wastewater, animal husbandry, industrial complexes and economic services) and surface sources (run-off from agricultural land uses) that generate wastes that potentially contaminate water bodies. The source locations were mapped and spatially joined with the drainage-basin map delineated from a Digital Elevation Model (DEM) to calculate the loads for the sub-basin units. Multivariate analysis then showed that the farming and domestic sources had the strongest positive loading factors for the sub-basins located in the city center and its fringe areas. Of these waste from animal husbandry account for up to 75.1% of total pollutant load. The main conclusion from the study’s results is that the management approach should be changed from the total controlling mode, which is currently applied in the city, to a source specific approach based on the pollutant discharge loads and the allocated capacities.

Potential variability of discharge and suspended sediment load in the Sone River basin, Bihar

Potential variability of discharge and suspended sediment load in the Sone River basin, Bihar

Hydro‐Sedimentary Processes of a Plunging Hyperpycnal River Plume Revealed by Synchronized Remote Imagery and Gridded Current Measurements

AbstractThe present knowledge of plunging hyperpycnal river plumes is mainly based on two‐dimensional (confined) laboratory experiments. Several hypotheses on three‐dimensional (unconfined) flow processes have been made, but not tested in situ. In this field study, the dominant three‐dimensional hydro‐sedimentary processes related to unconfined plunging were elucidated by synchronizing autonomous time‐lapse camera images with boat‐towed acoustic Doppler current profiler measurements. It was found that the flow field complies with two‐dimensional conceptualizations along the plume centerline. Perpendicular to the centerline, the plume slumped laterally due to its density excess and simultaneously converged laterally due to its vertical divergence. This combination led to a narrowing of the plume near the surface, resulting in a sediment‐rich triangle‐shaped pattern on the surface near the inflow, and a rather stable width near the bed. The formation of secondary flow cells transporting riverine water and suspended particulate matter (SPM) away from the plume near the bed, up toward the surface and back toward the plume near the surface, was revealed. An increase of the average SPM concentration and the SPM flux in the main flow direction indicates net sediment erosion under the investigated conditions of high discharge and sediment load. This suggests transient storage of sediment during conditions of lower discharge and sediment load, and high morphological activity in the plunging area. These findings allowed extending a classical conceptual plunging model to laterally unconfined sediment‐laden plunging inflows for conditions of well‐mixed ambient water in the plunging region and inflow densimetric Froude numbers exceeding 1, common in nature.

The Impact of Non-Point Source (NPS) Management on Non-Point Source Reduction and Water Cycle Improvement in an Urban Area

Suwon, the capital and largest city of Gyeonggi-do, South Korea, was designated as a non-point source management area in 2010. The management period ended in 2020, so follow-up measures are needed. In this study, we investigated several projects implemented in Suwon for urban water cycle improvement and non-point source pollution reduction, and the long-term management effects were analyzed to suggest policy directions such as the revision of designation notices. During the 10-year management period in Suwon, the population and lot area continued to increase, and the non-point source-based annual Biochemical Oxygen Demand (BOD) discharge loads also increased by approximately 25% at the half sub-basins Hwangguji-cheon and Woncheonri-cheon in 2020 compared to 2010. Even under these conditions, statistical analyses show that the Biochemical Oxygen Demand (BOD) and Total Phosphorus (TP) concentrations monitored at the outlet of basin were decreased due to the promotion of a large-scale sewer management project as well as non-point source pollution reduction projects. Also, the field monitoring data-based Load Duration Curve (LDC) analysis results indicate that the loads decreased in the high-flow period of 2020 compared to 2015. Also, the Normalized Difference Vegetation Index (NDVI) values calculated using satellite images since 2017 tended to increase slightly during the period when the impervious area estimated using the land registration map increased. It is assumed that using the current calculation method for impervious areas has limitations regarding its ability to reflect changes in the small-scale Low-Impact Development (LID) facility and in ecological/landscape areas. On the other hand, the annual variation in direct runoff estimated at the outlet using three hydrograph separation methods did not show any improvement with regard to storm water retention during the management period. These results reveal that the effects on urban water cycle improvement, such as peak flow reduction and base flow increase, may not be noticeable despite some progress in reducing non-point source pollution and increasing green area. Therefore, additional efforts directed towards non-point source pollution management focused on water cycle improvement are required in the city, especially in the sub-basins with higher pollution loads such as Hwangguji-cheon and Seoho-cheon.