Urban River Basin Research Articles

Weather Radar Data and Distributed Hydrological Modelling: An Application for Mexico Valley

The frequent occurrence of exceptionally very heavy rainfall in Mexico during the summer causes flash floods in many areas and major economic losses. As a consequence, a significant part of the annual government budget is diverted to the reconstruction of the disasters caused by floods every year, resulting hold up in the country development. A key element to mitigate the flash flood hazards is the implementation of an early warning system with the ability to process the necessary information in the shortest possible time, in order to increase structural and non-structural resilience in flood prone regions. The real-time estimation of rainfall is essential for the implementation of such systems and the use of remote sensing instruments that feed the operational rainfall-runoff hydrological models is becoming of increasing importance worldwide. However, in some countries such as Mexico, the application of such technology for operational purposes is still in its infancy. Here the implementation of an operational hydrological model is described for the Mixcoac river basin as part of the non-structural measures that can be applied for intense precipitation events. The main goal is to examine the feasibility of the use of remote sensing instruments and establish a methodology to predict the runoff in real time in urban river basins with complex topography, to increase the resilience of the areas affected by annual floods. The study takes data from weather radar operated by the National Meteorological Service of Mexico, as input to a distributed hydrological model. The distributed unit hydrograph model methodology is used in order to assess its feasibility in urban experimental basin. The basic concepts underlying the model, as well as calibration and validation are discussed. The results demonstrate the feasibility of using weather radar data for modeling rainfall-runoff process with distributed parameter models for urban watersheds. A product resulting from this study was the development of software Runoff Forecast Model (ASM), for application in distributed hydrological models with rainfall data in real time in watersheds with complex terrain, which are usually found in Mexico.

Indirect Estimation of Design Flood in Urbanized River Basins Using a Distributed Hydrological Model

AbstractA method for indirect estimation of design flood in poorly gauged urbanized river basins by using distributed hydrological modelling is presented. It is based on the critical flood design criterion that maximizes peak flow for a given return period by transforming precipitation of depth duration frequency curve into runoff. The indirect method is compared against the direct method based on regional approach and index flood estimation. This paper shows that the direct method significantly underestimates design flood in case discharge measurements are strongly affected by artificial alteration of water courses with possible catastrophic consequences in terms of loss of life and damage to property when the cause of alteration would be removed. Moreover, the use of a spatially distributed model allows taking into account the heterogeneity that generally characterizes river basins with an high degree of urbanization. The presented indirect method provides a design hydrograph that is useful for those ca...

Parsimonious hydrological modeling of urban sewer and river catchments

Summary A parsimonious model of flow capable of simulating flow in natural/engineered catchments and at WWTP (Wastewater Treatment Plant) inlets was developed. The model considers three interacting, dynamic storages that account for transfer of water within the system. One storage describes the “flashy” response of impervious surfaces, another pervious areas and finally one storage describes subsurface flow. The sewerage pipe network is considered as an impervious surface and is thus included in the impervious surface storage. In addition, the model assumes that water discharged from several CSOs (combined sewer overflows) can be accounted for using a single, characteristic CSO. The model was calibrated on, and validated for, the Vidy Bay WWTP, which receives effluent from Lausanne, Switzerland (population about 200,000), as well as for an overlapping urban river basin. The results indicate that a relatively simple approach is suitable for predicting the responses of interacting engineered and natural hydrosystems.

Spatial and temporal patterns of surface water quality and ichthyotoxicity in urban and rural river basins in Texas

The Double Mountain Fork Brazos River (Texas, USA) consists of North (NF) and South Forks (SF). The NF receives urban runoff and twice-reclaimed wastewater effluent, whereas the SF flows through primarily rural areas. The objective of this study was to determine and compare associations between standard water quality variables and ichthyotoxicity at a landscape scale that included urban (NF) and rural (SF) sites. Five NF and three SF sites were sampled quarterly from March 2008 to March 2009 for specific conductance, salinity, hardness, pH, temperature, and turbidity; and a zebrafish (Danio rerio) embryo bioassay was used to determine ichthyotoxicity. Metal and nutrient concentrations at all sites were also measured in addition to standard water quality variables in spring 2009. Principal component analyses identified hardness, specific conductance, and salinity as the water variables that best differentiate the urban NF (higher levels) from rural SF habitat. Nutrient levels were also higher in the NF, but no landscape scale patterns in metal concentrations were observed. Ichthyotoxicity was generally higher in NF water especially in winter, and multiple regression analyses suggested a positive association between water hardness and ichthyotoxicity. To test for the potential influence of the toxic golden alga (Prymnesium parvum) on overall ichthyotoxicity, a cofactor known to enhance golden alga toxin activity was used in the bioassays. Golden alga ichthyotoxicity was detected in the NF but not the SF, suggesting golden alga may have contributed to overall ichthyotoxicity in the urban but not in the rural system. In conclusion, the physicochemistry of the urban-influenced NF water was conducive to the expression of ichthyotoxicity and also point to water hardness as a novel factor influencing golden alga ichthyotoxicity in surface waters.

Developing a diatom monitoring network in an urban river-basin: initial assessment and site selection

There is increasing interest in the restoration of urban river systems because they are affected by multiple point- and diffuse-source impairments. In South Wales, these issues are exemplified by the rivers Taff and Ely, which have a well-documented history of pollution. We developed a network of river-monitoring sites to capture as many sources of impairment as possible and to provide an integrated assessment of basin-wide conditions using established, recently revised and new methods to assess ecological status as required by the Water Framework Directive (WFD). Most of the 34 river sites, except those in upstream areas, had moderate or poor ecological status and low species richness. There were significant correlations between the UK Trophic Diatom Index (TDI), phosphate and nitrate concentrations, but the strongest correlation was with sodium concentrations. Sodium also differentiated best between ecological status classes. The UK TDI, Ecological Quality Ratios and the Indice de Polluosensibilite Specifique (IPS) correlated strongly, but the IPS reflected chemical conditions less well. There were also possible metal impacts including some upstream sites despite apparently good or high ecological status. These data reveal strong capacity in diatoms for reflecting stressors that affect urban river networks. We recommend (i) further assessments including geographically comprehensive and repeated surveys to underpin local decision-making and (ii) further refinement of the tools currently in use for WFD purposes through the development of specific diagnostic indices or multi-metric methods for a comprehensive assessment of complex catchments affected by multiple impairments.

Predator-driven biotic resistance and propagule pressure regulate the invasive apple snail Pomacea canaliculata in Japan

Species richness in local communities has been considered an important factor determining the success of invasion by exotic species (the biotic resistance hypothesis). However, the detailed mechanisms, especially the role of predator communities, are not well understood. We studied biotic resistance to an invasive freshwater snail, Pomacea canaliculata, at 31 sites in an urban river basin (the Yamatogawa) in western Japan. First, we studied the relationship between the richness of local animal species and the abundance of P. canaliculata, demonstrating a negative relationship, which suggests that the intensity of biotic resistance regulates local snail populations. This pattern was due to the richness of native predator communities rather than that of introduced species or non-predators (mainly competitors of the apple snail). Local snail abundance was also affected by immigration of snails from nearby rice fields (i.e. propagule pressure), where few predators occur. Second, we assessed short-term predation pressure on the snail by means of a tethering experiment. Predation pressure was positively correlated with the number of individual predators and negatively correlated with snail abundance. The introduced crayfish Procambarus clarkii was responsible for the variance in predation pressure. These results indicate that the predator community, composed of both native and introduced species, is responsible for resistance to a novel invader even in a polluted urban river.

Field survey of pollutants discharged from different types of residential area in the Yamuna River Basin, India

The Ganges River, one of the most heavily populated and urbanized river basins in Asia, is polluted by increasing wastewater influent and water-borne diseases are caused in the metropolitan area. This study focused on the Yamuna River, a major tributary of the Ganges. We determined the pollutant load per unit of urban area classified by the income of the residents to help design an appropriate sewerage system. In addition, a simple method of estimating runoff pollutant load was examined using data on pollutant load per unit and runoff coefficient.

Spatial rainfall analysis for an urbanized tropical river basin

Spatial distributions of the storms are important since it is a major factor influencing flood formation in urban areas. However, the spatial allocations of rainfall data obtained from the interpolation method have many uncertainties. Thus, it is the objective of this research to derive the spatial distribution of storm events by using grid-based Kriging method. The best semi-variogram (SV) model is found for Kriging interpolation technique. Rectified skew orthomorphic (RSO) coordinates of 28 rainfall stations, located at upper part of the Klang river basin (675 km2) Malaysia, were used for generating a continuous storm event map using raster GIS software. The standard indicator for spatial correlations, Geary’s C, Moran’s I and SV were calculated for all events. These correlation coefficients are indicative of the spatial structure of point data. Continuous theoretical variogram models were plotted by using experimental variogram model. Positive correlation was found at average distance class of 6273 m for the pair-points. Based on the spatial correlation, maximum effective radius for a gauging station was found to be 3136 m. It was found that Gaussian model gave slightly better rainfall estimation at the position of samples as compared to the exponential and spherical models. Key words: Kriging, spatial correlation, rainfall pattern, Gaussian model, Klang river basin.

Research Trend of Eco-Security and Relevant Topics-Taiwan and Mainland China as Case Study

The design of this study employed an approach of literature review. Data were collected primarily by means of the search for the key word ‘ eco-security’ on the Internet in order to analyze and classify the related studies. This study organized the works, relative to the type of landscape , published in Chinese and English online journals by researchers in Taiwan and Mainland China. This pilot study tried to broaden the ground of limited research on eco-security by searching for more related online information including ‘ecological security’, ‘ecosystem & security’, ‘ecosystem & risk assessment’ and ‘environmental monitor & early-warning’. Therefore, this study had two purposes. One was to understand the classification, number and trend of the related research on eco-security through literature review. The other was to analyze the content of the related research on eco-security. This involved understanding the theories, assessment approaches, assessment subjects, applied instruments and new possibilities of the future study in this field. Our data consisted of 233 studies published from 1988 to 2010. In terms of issues, data were divided into four parts: eco-security, landscape security patterns, ecosystem risk and environmental monitor &early-warning. In terms of subjects , data were differentiated into urban areas, rural areas, river basins and particular areas and un-designated ones. In terms of purposes, three types of data were distinguished: theories, applications and dynamics. Finally, semi-natural or artificial ecosystem becomes the focus and Data Mining Theory’s tools will be used generally for constructing the non-linear model of eco-security assessments

Distribution and origin of polycyclic aromatic hydrocarbons in surface sediments from an urban river basin at the Metropolitan Region of Curitiba, Brazil

The concentrations of 16 polycyclic aromatic hydrocarbons (PAHs) were determined in surface sediment samples from nine sites located at the Iguaçu River Basin in the Metropolitan Region of Curitiba, Brazil to evaluate their distribution and sources. The total concentration of the PAHs was greater for sediments from highly urbanized areas, while the sediments from the Iraí Environmental Protection Area (Iraí EPA) showed significantly low concentrations. The sediments from the Iguaçu and Barigui rivers were classified as highly contaminated, while those from the Cercado and Curralinho rivers were classified as moderately contaminated. The predominance of PAHs containing two to four aromatic rings in most of the samples suggested the direct input of raw sewage into the water resources evaluated. Benzo[g,h,i]perylene, dibenzo[a,h]anthracene and indeno[1,2,3-cd]pyrene were predominant in sediments from the areas under the greatest urban and industrial development. The correlation between thermodynamic stability and the kinetics of evolution presented by the isomeric pairs indicated that combustion is the predominant source of PAHs in the sediments because the combustion of fossil fuels affected most of the points evaluated, followed by combustion of biomass and eventually combustion of oil product inputs. In general, the results showed that areas under strong urban influence, as well as the Iraí EPA, receive contributions of PAHs from similar sources.

SINGULAR VECTOR METHOD ON SHORT-TERM RAINFALL PREDICTION USING RADAR FOR HYDROLOGIC ENSEMBLE PREDICTION

Ensemble rainfall short-term prediction with flood simulation in urban river basin is presented. Considering the small scale of storm event, the radar echo extrapolation by translation model was used for predicting rainfall from X-band polarimetric radar. A new attempt of the ensemble prediction system by using initial condition perturbed by singular vector was introduced to find perturbations of advection vector, which linearly grow most rapidly. The methodology was demonstrated throughout case studies in Kofu urban river basin, Japan, with convective and stratiform precipitation system cases. SV found two leading perturbations over three hour prediction, giving five ensemble members. The members were subsequently considered as uncertain input of distributed hydrological model for developing ensemble flood prediction. Verified with observed data, this approach could serve as a reliable and effective system for operational flood disaster prevention in urban area.

Captura de Resíduos Sólidos Drenados em uma Bacia Hidrográfica Urbana

The production of solid wastes has increased due to the rapid growth of population. When the waste is disposed of inappropriately and carried into the storm drainage system, there are environmental consequences such as the accumulation of wastes in the storm sewerage system, reducing the runoff capacity of conduits and urban rivers and lakes, and pollutants are transported in this material. Therefore it is important to create strategies to monitor these wastes, with better management of urban river basins. The purpose of this work was to present a structure to capture the solid wastes carried by the water flow in a basin with urban characteristics, located in the central region and completely contained in the city of Santa Maria, state of Rio Grande do Sul, Brazil. It must be robust to resist weather conditions and it must allow continuous monitoring. In addition the wastes carried by drainage in ten rainfall events are quantified and qualified. Finally, it was found that the structure implemented was efficient to retain the wastes, and that they were mainly comprised of organic matter including plant litter which made up 67% of the total mass of quantified wastes, followed by plastics (14%)

Quaternary Ammonium Compounds in Urban Estuarine Sediment Environments - A Class of Contaminants in Need of Increased Attention?

The distributions of wastewater-derived quaternary ammonium compounds (QACs) were determined in surficial sediments (n = 47) collected from the urbanized lower Hudson River basin. The most abundant class of QACs were dialkyldimethylammonium compounds (DADMACs, with C8 to C18 carbon chain lengths; median ΣDADMAC = 26 μg/g), followed by benzylalkyldimethylammonium compounds (BAC, C12-C18; 1.5 μg/g), and alkyltrimethylammonium compounds (ATMAC, primarily C16 and C18; 0.52 μg/g). The concentrations of total QACs are higher than those of other conventional organic contaminants determined on the same samples (e.g., median ΣPAH level of 2.1 μg/g). Comparatively high concentrations, correlations with sewage derived contaminants, and the relatively constant compositions of QACs observed over large areas suggest that many sediment-sorbed QACs can be relatively persistent in receiving waters. Unusually large concentration-dependent sorption is considered as a mechanism that likely affects persistence of these intrinsically biodegradable chemicals under field conditions. There has been comparatively little field-based research on these classes of cationic surfactants; given the levels of QACs observed here, it is suggested that further investigation is warranted.

Assessment of satellite-based rainfall estimates in urban areas in different geographic and climatic regions

This paper presents an assessment of the 3B42 research version rainfall product from NASA’s Tropical Rainfall Measuring Mission Multi-satellite Precipitation Analysis (TMPA). The study provides new results of TMPA data accuracy in urban areas and highlights trends associated with the climatological indicators of temperature and relative humidity in cities. Ten years (1998-2007) of TMPA data were analyzed for three case study cities in the United States (Houston, Atlanta, and Las Vegas) and one in Korea (Cheongju), representing semi-arid to humid climates. At each location, an urbanized river basin and non-urbanized river basin were selected and comparisons between TMPA and rain gage observations were made for recorded storm events in the study period, the largest storm events by total depth, and selected hurricanes and topical storms. The results indicate TMPA data match well with rain gage observations at all locations. TMPA is slightly underestimated for semi-arid regions and overestimated for humid regions. The relative magnitude of TMPA rain event accumulation compared to rain gage accumulation is noted to be smaller for urbanized watersheds and high intensity events. The correlation of TMPA accuracy with temperature and relative humidity and the analysis of accuracy by season indicate TMPA is more accurate for convective rainfall events. This suggests a possible linkage between the observed urban-modified temperatures, hypothesized enhanced convection, and improved TMPA accuracy in urban areas.

Monitoring of organic load in a tropical urban river basin (Cameroon) by means of BOD and oxydability measurements

The tenor in organic matter has been assessed in an urban aquatic ecosystem the Mfoundi River Basin of Cameroon.The double technique of the Biochemical Oxygen Demand (BOD5) and the Oxydability test have been employed in this assessment. The results obtained indicate a high content of organic matter in the watershed with the highest values of BOD 297.5mg O2dm–3 and Oxydability 50.255mg O2dm–3 observed at the Akeu stream. The spearman correlation coefficient between BOD5 and Oxydability for the seasonal distribution is 0.22 which is positive but not statistically significant due to a high variability of biodegradable and non-biodegradable organic matter present in the river basin. The same value calculated between these organic tests with respect to the sampling sites is negative (–0.15) due probably to their abiotic and biotic heterogeneity. The results reveal a high tenor in organic matter in the hydro-system during the dry season, with a relative reduction during the rainy season, a situation that exposes the population of Yaoundé and its environs to acute pollution which can lead to numerous water related health hazards.

Sediments in urban river basins: a review of sediment–contaminant dynamics in an environmental system conditioned by human activities

Over 50% of the global population live in urban centres and, therefore, an understanding of the processes acting upon urban systems is a global issue. The nature of human-made, often impervious, land surfaces and heavily engineered waterways results in hydrological and sedimentological systems in urbanised basins which contrast significantly to those within more natural (i.e. pristine, forested, agricultural) aquatic systems. In addition, the abundance of contamination sources in urban systems results in chemical pressures often manifested as high pollution concentrations or loadings, which in turn have detrimental impacts on human and ecosystem health. These lead to management and sustainability issues not generally encountered in more natural environments. The purpose of this review is to provide a state-of-the-art assessment of sediment sources, pathways and storage within urban river systems, to consider sediment management within urban systems and river basins, and examine the role of local and global environmental changes on sediment processes and management. Inevitably, much of the sediment that is transported within urbanised basins is contaminated, so this review also considers sediment–contaminant sources and interactions. We reach a number of conclusions and recommendations for future research. There is a need for better sampling and monitoring of sediment and sediment-associated contaminant fluxes and cycling in urban river channels and basins. This should include better techniques and studies to identify sources and transfers of road-deposited sediment (RDS), airborne particulate matter and sediments in the river system. Greater interdisciplinary research, combining sedimentologists, hydrologists, urban planners, urban archaeologists, chemists and biologists, is needed. More attention needs to focus on upscaling and connecting urban areas to the rest of the river basin, both upstream and downstream. Finally, there is a need to balance multiple needs (urban population, water resources) with likely trends in both urban development and global environmental change.

Impact of value-driven scenarios on the geomorphology and ecology of lower Rhine floodplains under a changing climate

The biogeomorphological functioning of lowland floodplains will be altered strongly due to future landscaping measures that are necessitated by climate change. For many industrialized and urbanized river basins, the layout of the fluvial area depends on the human choices for landscaping measures, which reflect the dominant value system of the actors. We aimed at (1) designing scenarios for the future layout of the floodplains of the River Waal in the Netherlands for 2050 using a new value-based methodology, and (2) assessing the floodplain biogeomorphology under these scenarios and climate change. The scenarios are driven by transitions in human value systems and they are color-coded: green (personalistic-consensual), orange (scientific-rational), and yellow (integrated-systemic). Per scenario, the landscaping measures were translated into a future topography and ecotope distribution. Using various spatially explicit simulation models, we evaluated the scenarios regarding the biogeomorphology in 2050: (1) flood peak reduction (green 0.11, orange 0.65, and yellow 0.37 m), (2) year-average floodplain suspended sediment deposition (+114, +148, +143%), (3) food web exposure to heavy metals (4–5 out of 10 species for all scenarios) and (4) biodiversity value (+23, −4, +39%). We conclude that (1) analysis of value systems provides a broad interpretive framework for scenario development, which guides the choices for transitions and (2) the biogeomorphology is affected by climate change (+58% deposition), but the effects of the local landscaping measures are even stronger. None of the scenarios shows the ideal combination of high flood peak reduction, low sedimentation, and high biodiversity. Ecotoxicological risks seem less discriminative.

Spatial Variation of Metal Concentrations in Watercourses of an Urban River Basin in Southeastern Brazil

Spatial patterns of water quality at 29 sites, in a mixed land use watershed located in southeastern Brazil, were examined for eight metals, sampled over nine years -Arsenic, Cadmium, Copper, Lead, Mercury, Nickel, Selenium, and Zinc. Data analysis included delineation of the area of influence of each monitoring station, based on GIS analysis of Shuttle Radar Topography Mission (SRTM) images, estimation of the upper prediction limit 95% (UPL95) with censored data by the Kaplan-Meier technique, hierarchical cluster analysis (CA), Kruskal-Wallis and Friedman test. The locations of the groups generated by CA agreed with land and soil use and impact of anthropogenic activities. Use of UPL95 as entry data in CA allowed better use and interpretation of monitoring data. Areas with natural background metal-concentration levels in the drainage basin and areas of concern were identified.

MAPEAMENTO DE CARACTERÍSTICAS FÍSICAS DO RELEVO DA CIDADE DE GUARAPUAVA-PR UTILIZANDO TÉCNICAS DE GEOPROCESSAMENTO

O relevo é o principal agente físico que interfere a ocupação urbana. Normalmente, essa se inicia em áreas mais favoráveis e, somente depois, com a expansão urbana acabam ocupando áreas impróprias. É neste viés que se insere a presente pesquisa, visando elaborar um estudo integrado das características físicas do relevo no perímetro urbano da cidade de Guarapuava-PR. Para isso utilizou-se de três procedimentos metodológicos: pesquisa bibliográfica; trabalhos de campo e de laboratório/gabinete. Com o auxílio de técnicas de geoprocessamento e utilização do software SPRING versão 4.3.3, foram realizados mapeamentos para cada variável (hidrografia e bacias hidrográficas urbanas, hipsometria, declividade, exposição de vertentes, solos e formas de relevo). Conhecer as características físicas do espaço urbano, as limitações e as potencialidades torna-se de grande valia para o estabelecimento de práticas mais racionais de uso do solo e de um planejamento urbano mais condizente com tais especificidades.

Combined use of Daphnia magna in situ bioassays, biomarkers and biological indices to diagnose and identify environmental pressures on invertebrate communities in two Mediterranean urbanized and industrialized rivers (NE Spain)

Environmental factors affecting aquatic invertebrate communities were assessed using Daphnia magna in situ bioassays and biological indices based on community assemblages of benthic macroinvertebrates. Investigations were carried out in two heavily industrialized and urbanized river basins from the NE of Spain (Llobregat and Besós). Measures of energy consumption (i.e. algal grazing), and of specific biochemical responses (biomarkers) were conducted on individuals transplanted upstream and downstream from effluent discharges of sewage treatment plants. In both rivers there was a clear deterioration of the ecological water quality parameters and benthic communities towards downstream reaches. In all but one of the 19 locations studied, transplanted organisms were affected in at least one of the five measured responses. In three of them, significant effects were detected in most of the traits considered. Principal Component and Partial Least Square Projections to Latent Structures regression analyses indicated that the measured responses in D. magna in situ bioassays and those of macroinvertebrate assemblages were affected by distinct environmental factors. From up to 20 environmental variables considered, seven of them including habitat degradation, suspended solids, nitrogenous and conductivity related parameters affected macroinvertebrate assemblages. On the other hand, levels of organophosphorus compounds and polycyclic aromatic hydrocarbons were high enough to trigger the responses of D. magna in situ bioassays. These results emphasize the importance of combining biological indices with biomarkers and more generalized and ecologically relevant (grazing) in situ responses to identify ecological effects of effluent discharges from sewage treatment plants in surface waters.