Assessing Uncertainty of a Biofilter Micropollutant Transport Model MPiRe

MPiRe (Micro-Pollutants In RaingardEns) model was developed to predict both flows and removal of micropollutants by stormwater biofilters. It is a conceptual 1D model that includes sorption/desorption, biodegradation and volatilization processes. This paper presents an uncertainty evaluation of MPiRe using the GLUE methodology with atrazine as a representative pollutant. The uncertainty analysis shows that the soil-water partitioning coefficient (normalized to organic carbon content) is the most sensitive model parameter, while there is some correlation between sorption parameters and high uncertainty in the degradation rate estimation. It is hypothesized that the correlation between sorption parameters can be diminished by choosing two different combinations of calibration parameters (e.g. variations of their mutual products), and this hypothesis will be further tested. The practical implication of this analysis is that particular care should be given to measurements of initial outflow concentrations of events (to decrease the uncertainty in the degradation rate estimation). Additionally, if it is necessary to prioritize between monitoring procedures, the most attention should be given to sorption kinetics.</p

Uncertainty in environmental and hydrological mathematical modelling

The current state of knowledge regarding uncertainties in urban drainage models is poor. This is in part due to the lack of clarity in the way model uncertainty analyses are conducted and how the results are presented and used. There is a need for a common terminology and a conceptual framework for describing and estimating uncertainties in urban drainage models. Practical tools for the assessment of model uncertainties for a range of urban drainage models are also required to be developed. This paper, produced by the International Working Group on Data and Models, which works under the IWA/IAHR Joint Committee on Urban Drainage, is a contribution to the development of a harmonised framework for defining and assessing uncertainties in the field of urban drainage modelling. The sources of uncertainties in urban drainage models and their links are initially mapped out. This is followed by an evaluation of each source, including a discussion of its definition and an evaluation of methods that could be used to assess its overall importance. Finally, an approach for a Global Assessment of Modelling Uncertainties (GAMU) is proposed, which presents a new framework for mapping and quantifying sources of uncertainty in urban drainage models

Modelling to support the planning of sustainable urban water systems

Water Sensitive Urban Design (WSUD) is commonly employed to restore urban water systems back to pre-developed conditions and can provide multiple benefits. However, WSUD planning is a challenging task that involves multidisciplinary effort to deal with highly complex and uncertain futures. Hence, an integrated approach is required to address this task with a high level of scientific rigour. This paper introduces an integrated modelling tool – UrbanBEATS (Urban Biophysical Environments And Technologies Simulator) which supports the planning and development of sustainable urban water strategies. Initially developed to plan WSUD stormwater infrastructure for management of runoff, pollution and stormwater harvesting, UrbanBEATS’ ecosystem is currently being extended and includes, among others, three new modules, which are introduced in this paper: (1) uptake, needs and suitability assessment module for simulating the behaviour of the main actors in urban stormwater management to assess uptake, suitability and needs for WSUD technologies; (2) mapping of water pollution emissions, linking detailed information of the urban form and land use with stormwater pollution algorithms (allowing identification of pollution hotspots within the catchment to guide pollution management strategies); and (3) a novel cellular automata fast flood evaluation model known as CA-ffé for the rapid prediction of inundation extent, depths and flood risks in urban areas (including assessment of the WSUD benefits for reducing flood damages)

Assessment of loose and adhered urban street sediments and trace metals: a study in the city of Po double dagger os de Caldas, Brazil

This study aims to quantify and characterise sediments accumulated in the street gutters in an urban area of Po double dagger os de Caldas, Brazil. The main research questions are: What type of urban areas, e.g. those under construction, produce most sediments and what are the main characteristics of such sediments? What differences, e.g. granulometry, can be found in loose and adhered sediments? What trace metals can be found in the sediments?Fieldwork was carried out in a residential area of Po double dagger os de Caldas, Brazil. Ten samplings were conducted between May and August 2013 to collect sediments from road gutters. The collected sediments were then divided into 'loose' and 'adhered', depending on whether they were collected in a first, gentle, sweeping with soft bristled brush or in a subsequent sweeping with a stiff bristled brush. Granulometric curves were drawn for both types of sediments. Fine sediment analyses (aecurrency sign63 mu m) were performed on samples from the last five samplings. Two techniques were used to look for trace elements: energy dispersive X-ray fluorescence (EDXRF) and inductively coupled plasma-atomic emission spectrometry (ICP-AES).Larger amounts of sediments were collected after lower intensity rainfall events. Higher intensity events seemed to wash the sediments away. A correlation was found between areas under construction and sediment mass production. A characteristic range of granulometries (medium sand), found in our study is in accordance with studies by other authors. An important presence of heavy metals (Cr, Cd, Pb, Zn, Ni and Cu) was detected and characterised. As and Sn were also detected even though they are not often mentioned in the literature on urban soil pollutants.Areas under construction were found to produce more sediments than other areas. The trace metals found in highest concentrations were Pb and As. The heavy metal concentration decreases after wet periods, showing that they are carried by runoff. It is expected that this study may serve as an input for establishing diffuse pollution control and mitigation strategies for the accumulation of pollutants in the urban environment