Urban Catchment Research Articles

Influences of Zinc Loads in Urban Catchment Runoff: Roof Type, Land Use Type, Climate and Management Strategies

Influences of Zinc Loads in Urban Catchment Runoff: Roof Type, Land Use Type, Climate and Management Strategies

Predicting the Relationship between Lulc Changes and Their Impact on Lst by Molusce and Gee Environment in Urban Catchment of Kolkata City

Predicting the Relationship between Lulc Changes and Their Impact on Lst by Molusce and Gee Environment in Urban Catchment of Kolkata City

Risk assessment for inland flooding in a small urban catchment : Focusing on the temporal distribution of rainfall and dual drainage model

Risk assessment for inland flooding in a small urban catchment : Focusing on the temporal distribution of rainfall and dual drainage model

Evaluation of nitrogen loading in the last 80 years in an urbanized Asian coastal catchment through the reconstruction of severe contamination period

Most semi-enclosed seas have experienced severe eutrophication owing to high nutrient loading from rivers during rapid population growth periods. In Japan, the coastal areas of some megacities (e.g. Tokyo and Osaka) experienced considerable economic growth during the 1960s–1970s. Therefore, determining the amount of nutrient loading during this period is essential to undertake measures for the conservation of coastal environments. However, determining the nutrient loading that occurred several decades ago is generally difficult owing to lacking water quality records. In this study, the nitrogen loading in the Yamato River catchment, an urbanized coastal catchment in Asia, for 80 years from the 1940s to the 2010s is reconstructed using the Soil and Water Assessment Tool. We considered factors such as population growth, wastewater treatment plant (WWTP) construction, and changes in land and fertilizer usage in different urbanization stages. Results show that the total nitrogen loading in the catchment peaked in the 1970s at 6616 tons yr−1 owing to untreated wastewater discharge and rapid increase in population growth. By reducing 57% of the nitrogen loading in the 2010s from the catchment, WWTPs have been instrumental in improving the water environment. The decrease in and integration of agricultural land has reduced nitrogen loading attributed to nonpoint sources; however, this reduction was not obvious because of the high fertilizer usage before the 2000s. Overall, the findings of this study provide a comprehensive understanding of the impact of rapid urbanization in an Asian coastal catchment on nitrogen loading during the high economic growth period in the past. This study will be useful for the long-term assessment of nutrient loading in other.

Bacterial assemblages of urban microbiomes mobilized by runoff waters match land use typologies and harbor core species involved in pollutant degradation and opportunistic human infections

Cities are patchworks of urban catchments divided into functional units according to their commercial, residential and industrial activities, and socio-urbanistic patterns. The hypothesis of city surface microbiomes being structured by socio-urbanistic variables leading to an emergence of synurbic taxa was tested. According to the r/K microbial ecology theory, a gradient of well-adapted synurbic K-strategists and of opportunistic –r-strategists should occur over city surfaces. K-strategists would be core components while r-ones would be transiently detected. To resolve these patterns, sub-catchments (n = 21) of an area of high commercial and industrial activities were investigated over three time periods covering one year. The sub-catchments' land use patterns and associated human behaviors were converted into socio-urbanistic variables and groupings. Bacterial cells mobilized by runoffs per sub-catchment were recovered, and analyzed by classical approaches, microbial source tracking DNA assays and DNA meta-barcoding approaches. Relationships between these datasets, the runoff physico-chemical properties, and descriptors of the socio-urbanistic groupings were investigated. 16S rRNA meta-barcoding analyses showed evidence of the occurrence of K- and r-like strategists. Twenty-eight core genera were identified, and correlation networks revealed large bacterial modules organized around actinobacterial taxa involved in hydrocarbon degradation processes. Other bacterial networks were related to the occurrences of hygienic wastes, and involved bacteria originating from fecal contaminations. Several r-strategists like Sulfurospirillum were recorded and found associated to point source pollutions. The tpm-metabarcoding approach deciphered these r / K strategists at the species level among more than ten genera. Nine core K-like Pseudomomas species were identified. The P. aeruginosa human opportunistic pathogen and P. syringae phytopathogens were part of these K-strategists. Other tpm-harboring bacterial pathogens showed r-like opportunistic distribution patterns. Correlation network analyses indicated a strong incidence of hygienic wastes and hydrocarbon-pollutions on tpm-harboring bacteria. These analyses demonstrated the occurrence of core synurbic bacterial K-strategists over city surfaces.

Characterizing the Stormwater Runoff Quality and Evaluating the Performance of Curbside Infiltration Systems to Improve Stormwater Quality of an Urban Catchment

The conveyance of stormwater has become a major concern for urban planners, considering its harmful effects for receiving water bodies, potentially disturbing their ecosystem. Therefore, it is important to characterize the quality of catchment outflows. This information can assist in planning for appropriate mitigation measures to reduce stormwater runoff discharge from the catchment. To achieve this aim, the article reports the field data from a typical urban catchment in Australia. The pollutant concentration from laboratory testing is then compared against national and international reported values. In addition, a stochastic catchment model was prepared using MUSIC. The study in particular reported on the techniques to model distributed curbside leaky wells with appropriate level of aggregation. The model informed regarding the efficacy of distributed curbside leaky well systems to improve the stormwater quality. The results indicated that catchment generated pollutant load, which is typical of Australian residential catchments. The use of distributed storages only marginally improves the quality of catchment outflows. It is because ability of distributed leaky wells depended on the intercepted runoff volume which is dependent on the hydrological storage volume of each device. Therefore, limited storage volume of current systems resulted in higher contributing area to storage ratio. This manifested in marginal intercepted volume, thereby only minimum reduction in pollutant transport from the catchment to outlet. Considering strong correlation between contributing impervious area and runoff pollutant generation, the study raised the concern that in lieu of following the policy of infill development, there can be potential increase in pollutant concentration in runoff outflows from Australian residential catchments. It is recommended to monitor stormwater quality from more residential catchments in their present conditions. This will assist in informed decision-making regarding adopting mitigations measures before considering developments.

Rainfall-runoff modeling: A modification of the EBA4SUB framework for ungauged and highly impervious urban catchments

There are no doubts that prediction of runoff is one of the crucial hydrological research topics when dealing with catchments. It is noteworthy that the rapid land use change in catchments due to urbanization strongly modifies runoff formation, and the use of many common rainfall-runoff models often is not appropriate in such situations. Moreover, in small catchments with a high percentage of impervious areas, highly detailed hydrometeorological data are needed to calibrate the parameters of advanced rainfall-runoff models. Facing the new challenges of urban catchment runoff, this work presents a modification of the EBA4SUB (Event-Based Approach for Small and Ungauged Basins) rainfall-runoff model to improve its applicability in urban areas. The proposed approach is a combination of the original model with a newly formulated excess rainfall calculation (named P4URB) that considers pervious and impervious areas. Indeed the original EBA4SUB model does not consider impervious areas as a separate form of land use. Based on results, we can conclude that EBA4SUNURB (Event-Based Approach for Small and UNgauged Urban Basins) is better suited for urban catchments because it includes a more rational depiction of how impervious areas influence runoff formation. The shape of the design hydrograph and related peak flow are significantly different from those generated from the commonly used Nash model. The main advantage of EBA4SUNURB model is that it can be used in ungauged catchments because all parameters are calculated based on catchment characteristics as opposed to being estimated through a calibration process.

Simulation-optimization framework in urban flood management for historic and climate change scenarios

Abstract A simulation-optimization framework is established by integrating Hydrologic Engineering Center Hydraulic Modeling System (HEC-HMS) for computation of runoff, siting tool EPA System for Urban Storm-water Treatment and Analysis INtegration (EPA-SUSTAIN) for placement of Best Management Practices (BMPs), and Binary Linear Integer Programming (BLIP) for runoff reduction. The framework is applied to an urban catchment, namely Greater Hyderabad Municipal Corporation (GHMC). The rainfall-runoff analysis was conducted for extreme rainfalls for historic (2016) and future events in 2050 and 2064 under Representative Concentration Pathways (RCPs) 6.0 and 8.5. The simulation-optimization approach in the historic scenario yielded 495,607 BMPs occupying 76.99 km2 resulting in runoff reduction of 21.54 mm (198.76–177.22 mm). Achieved runoff reduction is 38.72 (428.35–389.63 mm) and 55.03 (602.65–547.62 mm), respectively, for RCPs 6.0 and 8.5, which could meet the water demands of GHMC for 10.33 and 11.53 days. Impacts of 10 different BMP configurations of varying costs (10–70%) and pollutant load reductions (0–3%) on runoff reduction are accomplished as part of sensitivity analysis.

Groundwater-surface water interactions and flux of organic matter and nutrients in an urban, Mediterranean stream

The chemical quality of dissolved organic matter (DOM) and the speciation of nitrogen exported from urban catchments is of great importance to biogeochemical cycling in riverine and coastal receiving waters. Many urban streams in Mediterranean climates have a flashy hydrologic regime, which would suggest a rapid pulsing and shunting of solutes downstream. However, the role of these systems both as passive pipes for solute transport or as reactors for DOM and nutrient transformation is still an open question for urban, Mediterranean streams. To address this question, we evaluated changes in concentrations of inorganic and organic solutes and DOM optical properties in Alvarado Creek, a perennially-flowing, urban, first-order tributary of the San Diego River in San Diego, CA, USA, during dry weather (baseflow) conditions and during four storm events in 2016–2018. Chloride and sulfate concentrations corroborate the supposed saline groundwater supply that maintains perennial flow and brackish nature in this urban stream. During dry weather, high proportions of protein-like fluorescent component (AC4) and downstream decreases in total dissolved nitrogen (TDN) and nitrate imply in-stream processing (nitrification and denitrification). By contrast, storm hysteresis curves indicate that the supply of DOM and TDN was not exhausted over the duration of a storm event, whereas nitrate was eventually depleted, presumably because nitrification could not keep up with the export of nitrate from source areas. Rapid decreases in chloride during the storm hydrograph coincided with a shift in specific ultraviolet absorbance (SUVA) and fluorescence index (FI) to more terrestrially-derived and aromatic carbon sources, most likely from interflow of stormwater through vadose zone soils. On an annual basis, the export of microbially-derived DOM during dry weather was higher than the export of terrestrially-derived DOM during storm events; both represent important carbon inputs to coastal waters.

Characterization and sources apportionment of overflow pollution in urban separate stormwater systems inappropriately connected with sewage

In recent years, combined sewer overflow (CSO) has been identified as a significant contributor to the deterioration of the urban water environment. It is thought that remolding it to a separate sewer system is a thorough and effective method of controlling the CSO in the appropriate area. However, according to current research, the separate stormwater sewer systems will also have overflow pollution due to functional defects, damaged or inappropriately connected with sewage, which has serious consequences for the separate system's operational efficiencies and the urban water environment. The event mean concentration, first flush effect, source apportionment, and correlation analysis of variables in overflow pollution generated in three residential catchments in Nanning, China, were investigated in this study. The results showed that the event mean concentration values in drainage outlets inappropriately connected with sewage were 2–4 times higher than those in stormwater outlets, especially for NH3–N, TN, and TP. Meanwhile, more than 80% of overflow events at outlets inappropriately connected with sewage had a weak first flush or even a weak dilution effect, with peak pollutant concentrations occurring 40–60 min after the overflow began. Besides, the discharge pollution load was primarily derived from the inside of the sewer. When the rainfall was heavy, the contribution rate of sewer sediment erosion exceeded 60%, which was much higher than the contribution rate of rainfall runoff and sewage. The variability in event mean COD and TSS concentrations was primarily attributed to the antecedent dry period and rainfall intensity. The COD concentration increased from 140.7 to 277.1 mg/L with the increase of antecedent dry period from 3 to 10 days. This study could help guide the implementation of targeted measures to treat overflow pollution in urban residential catchments, as well as the development of strategies to mitigate the effects on receiving water bodies.

Effects of land use, climate, and imperviousness on urban stormwater quality: A meta-analysis

Many natural and anthropogenic factors cause degradation of urban stormwater quality, resulting in negative consequences to receiving waters. In order to improve water quality models at a variety of scales, accurate estimates of pollutant (nutrients, total suspended solids, and heavy metal) concentrations are needed using potential explanatory variables. To this end, a meta-analysis was performed on aggregated stormwater quality data from the published literature from 360 urban catchments worldwide to understand how urban land use and land cover (LULC), climate (i.e., Kӧppen-Geiger zone), and imperviousness (1) affect runoff quality, and (2) whether they are able to predict stormwater pollutant concentrations. Runoff pollutant concentrations were more influenced by LULC and climate than imperviousness. Differences in LULC significantly affected the generation of metals and some nitrogen species. Road, city center, and commercial LULCs generally produced the most elevated pollutant concentrations. Changes in climate zones resulted in significant differences in concentrations of nutrients and metals. Continental and arid climate zones produced runoff with the highest pollutant concentrations. Rainfall patterns seemed to have a more important role in affecting runoff quality than seasonal temperature. Differences in imperviousness only significantly affected chromium and nickel concentrations, although increased imperviousness led to slightly (not significantly) elevated concentrations of nutrients, suspended solids, and other heavy metals. Multiple linear regression models were created to predict the quality of urban runoff. Predictive equations were significant (p < 0.05) for 67% of the pollutants analyzed (ammonia, total Kjeldahl nitrogen, total nitrogen, total phosphorus, cadmium, nickel, lead, and zinc) suggesting that LULC, climate, and imperviousness are useful predictors of stormwater quality when local field monitoring or modeling is not practical. This study provides useful relationships to better inform urban stormwater quality models and regulations such as total maximum daily loads.

Monitoring of wastewater quality in Lodz sewage system (Poland)—do the current solutions enable the protection of WWTP and receiving water?

Solving urban wastewater management problems requires knowledge of wastewater composition and variability. In the case of combined sewerage, this applies to both dry and wet weather. Wastewater composition is changing as a result of the appearance of new substances on the market, the changes in inhabitant lifestyle and the catchment characteristic; therefore, it must be constantly monitored. At the same time, due to the time-consuming and high costs of measurement campaigns, solutions that could limit their scope and facilitate the interpretation of the results are sought. This paper presents the results of the measurement campaign conducted in 2018–2021. The aim of the monitoring was, inter alia, assessment of wastewater composition in terms of threats to wastewater treatment plant and urban rivers, which are receivers of discharge from combined sewer overflows. The obtained results were analyzed using the multivariate statistical methods: Principal Component Analysis and Cluster Analysis. However, the applied methods did not allow for the full identification of the relationship between the wastewater quality parameters as well as the differences and similarities in the wastewater composition from individual parts of the city, which could simplify and reduce the measurement campaigns in the future. Therefore, in the case of large urban catchments, it is necessary to introduce other solutions to control the wastewater composition.

Urban Drool Water Quality in Denver, Colorado: Pollutant Occurrences and Sources in Dry-Weather Flows

Dry-weather flows in urban channels and streams, often termed “urban drool”, represent an important source of urban surface water impairment, particularly in semi-arid environments. Urban drool is a combination of year-round flows in urban channels, natural streams, and storm-sewer systems (runoff from irrigation return flow, car washes, street cleaning, leakage of groundwater or wastewater into streams or storm sewers, etc.). The purpose of this study was to better understand the extent and sources of urban drool pollution in Denver, Colorado by identifying relationships between urban catchment characteristics and pollutants. Water-quality samples were taken throughout Denver at urban drainage points that were representative of a variety of urban characteristics. Samples were analyzed for total suspended solids (TSS), coliforms, Escherichia Coli (E. coli), nutrients (nitrate, phosphorus, and potassium), dissolved and total organic carbon, and dissolved and total recoverable metals. Results from this study were as follows: (1) most contaminants (nitrate, phosphorus, arsenic, iron, manganese, nickel, selenium, and zinc) were concluded to be primarily loaded from shallow groundwater; (2) anthropogenic effects likely exacerbated groundwater pollutant concentrations and contributions to surface water; (3) nitrate, nickel, and manganese may be partially contributed by industrial inputs; (4) medical marijuana cultivation sites were identified as a potential source of nutrient and zinc pollution; (5) E. coli was a ubiquitous contaminant in all urban waterways; (6) erosion of contaminated urban soils, presumably from construction, was found to significantly increase concentrations of TSS, total phosphorus, and total metals. Increasing urbanization and predicted drier climates suggest that dry-weather flows will become more important to manage; the results from this study provide insight on dry-weather water quality management for the City and County of Denver.

Interaction of torrential and urban catchments – Pros and cons of storm sewer retentions

Interaction of torrential and urban catchments – Pros and cons of storm sewer retentions

Interaction of torrential and urban catchments – Pros and cons of storm sewer retentions

Interaction of torrential and urban catchments – Pros and cons of storm sewer retentions

Life-cycle cost analysis and resilience consideration for coupled grey infrastructure and low-impact development practices

Recent studies have suggested that coupling grey infrastructure (GREI) with low-impact development may be a promising approach to urban stormwater management. However, comprehensive assessment of the hydrological resilience of such a coupled-system is challenging, and this limits planning and implementation. In this paper the authors developed an innovative approach to measure and optimise life cycle costs for layouts with different levels of decentralisation under the constraint of hydrological reliability, and assess their technology-based and operational resilience. The authors found that coupled solutions implemented in a high-density catchment are economically competitive compared with conventional GREI. Based on the findings of risk scenario modeling, the coupled-systems show better technology-based resilience to extreme weather, except during extreme storms (rainfall of 50-year recurrence interval with 24-hr storm duration). Regarding operational resilience (versus structural failure), coupled-systems incorporating source control and pathway drainage with higher redundancy are more robust than GREI-only system. Decentralisation with optimised layouts does not significantly improve system resilience. This methodology could be a helpful decision-making tool in developing strategies to manage stormwater runoff for better hydrological resilience in high-density urban catchments.

Can fruit and vegetable aggregation systems better balance improved producer livelihoods with more equitable distribution?

The need for food systems to generate sustainable and equitable benefits for all is a global imperative. However, whilst ample evidence exists linking smallholder farmer coordination and aggregation (i.e. the collective transport and marketing of produce on behalf of multiple farmers) to improved market participation and farmer incomes, the extent to which interventions that aim to improve farmer market engagement may co-develop equitable consumer benefits remains uncertain. This challenge is pertinent to the horticultural systems of South Asia, where the increasing purchasing power of urban consumers, lengthening urban catchments, underdeveloped rural infrastructures and inadequate local demands combine to undermine the delivery of fresh fruits and vegetables to smaller, often rural or semi-rural markets serving nutritionally insecure populations. To this end, we investigate the potential for aggregation to be developed to increase fruit and vegetable delivery to these neglected smaller markets, whilst simultaneously improving farmer returns. Using an innovative system dynamics modelling approach based on an aggregation scheme in Bihar, India, we identify potential trade-offs between outcomes relating to farmers and consumers in smaller local markets. We find that changes to aggregation alone (i.e. scaling-up participation; subsidising small market transportation; mandating quotas for smaller markets) are unable to achieve significant improvements in smaller market delivery without risking reduced farmer participation in aggregation. Contrastingly, combining aggregation with the introduction of market-based cold storage and measures that boost demand improves fruit and vegetable availability significantly in smaller markets, whilst avoiding farmer-facing trade-offs. Critically, our study emphasises the benefits that may be attained from combining multiple nutrition-sensitive market interventions, and stresses the need for policies that narrow the fruit and vegetable cold storage deficits that exist away from more lucrative markets in developing countries. The future pathways and policy options discovered work towards making win-win futures for farmers and disadvantaged consumers a reality.

Land cover based simulation of urban stormwater runoff and pollutant loading

Urban stormwater models such as PCSWMM are important tools for evaluating urban stormwater quantity and quality. However, due to the lack of consideration of land covers, traditional catchment delineation methods have defects in model precision, parameter transferability and assessment of contribution from individual land cover types. This paper used PCSWMM model as a foundation, built a new land-cover based (LCB) model and made a systematic comparison with the traditional watershed delineation tool (WDT) model to study the impacts of land cover on the simulation of stormwater runoff and pollutant loading. The models were applied to two urban catchments in Calgary, Canada. The results revealed that the LCB model performed better than the WDT model in hydrological simulation, and land cover consideration can considerably improve model accuracy. The two models showed comparable performances in simulation of total suspended solids (TSS), total nitrogen (TN), and total phosphorus (TP) loading. The LCB model parameters could be regionalized based on land cover types. The hydrologic-hydraulic parameters can be satisfactorily transferred from neighboring gauged catchments to similar ungauged catchments. The transferring of water quality parameters did not perform as satisfactory. The LCB model could quantitively evaluate the contribution to runoff and pollutant loads of different land covers. Roads and roofs were found to be the major contributors to urban runoff and pollutants in the two urban catchments. Green space became important only during large storms events and its contribution could be ignored during dryer years.

Performance of nearest neighbour metrics for pluvial flood nowcasts in urban catchments

Urban flood warning systems need fast response times between the rainfall forecast and the flood alarm. Flood forecasts from physically based numerical models usually need much computation time. Flood forecasts based on databases from previous events or pre-simulated events can speed up the process of decision making. This work introduces and compares four distance metrics for temporal rainfall patterns used in a nearest neighbour based forecast system for dynamic water levels and velocities during pluvial floods. The system uses a database of 960 pre-calculated flood events. The performance of each metric is evaluated by analysis of time-series of flow variables. For the error quantification,a procedure to find a small number of representative locations in an urban catchment is described. A new approach to quantify the similarity of dynamic flow fields is introduced, which makes use of particle transport tracking. The four distance metrics are tested on forecast for four exemplary pluvial flood events resulting from rainfall of durations between 15 and 50 min and return-periods between 10 and 100 years. The best metric is based on the temporal precipitation pattern and takes the response time of the drainage system into account. If the pattern has a very short duration, a simpler characterisation-metric can be used, which takes the total volume, peak intensity and peak position into account.

Assessing alcohol consumption in a Chinese urban population and a university town using high temporal resolution wastewater-based epidemiology

BackgroundAlcohol consumption is a leading preventable risk factor for morbidity and mortality in China. Understanding drinking patterns provides important data to inform public health policies in alcohol control, especially in specific groups like university students. This study aims to assess the alcohol consumption patterns and level of use in an urban population and a university town in a Chinese city using wastewater-based epidemiology (WBE). MethodsDaily wastewater sample was collected from an urban catchment (n = 270) and every Wednesday’s sample from a university town of 10 university campus (n = 43) in 2017–2018. Concentration of alcohol consumption biomarker in wastewater, ethyl sulfate, was measured by direct injection LC-MS/MS analysis. Per capita daily alcohol consumption was then back calculated for assessment purposes. ResultsPer capita daily alcohol consumption was 1.4 ± 0.6 mL/ person aged 15 + /day (EPD) (range: 0.2–4.9) in the urban catchment and 1.3 ± 0.6 EPD (range: 0.3–2.6) in the university town. Trends of alcohol consumption were stable in both catchments in 2017–2018. Alcohol consumption on weekends (1.5 EPD) and weekdays (1.4 EPD) were at a similar level. Additionally, no difference was observed between holidays (1.5 EPD) and non-holidays (1.4 EPD). ConclusionThere is a stable weekly drinking level in the studied urban population, which is different compared to studies conducted in Western countries. Our study suggested a similar consumption level between the urban population and university students. Drinking during weekdays could negatively affect China’s economic productivity and future public health policies could be adapted to reflect this pattern of drinking.