DBPapers
DOI: 10.5593/sgem2012/s20.v5090

REGIONAL RELATIVE RISK RANKING OF DIFFUSE POLLUTION SOURCES IN AN URBAN ENVIRONMENT, GOTHENBURG (SWEDEN)

A. C. LAVERS, R. L. STEVENS
Wednesday 1 August 2012 by Libadmin2012

References: 12th International Multidisciplinary Scientific GeoConference, www.sgem.org, SGEM2012 Conference Proceedings/ ISSN 1314-2704, June 17-23, 2012, Vol. 5, 667 - 674 pp

ABSTRACT

Complex urban environments are not easily described in terms of ecological risks.
Relative regional risk ranking (developed by W.G. Landis) summarizes the impact of
multiple parameters within a region considering their source and distribution. As part of
the EU Interreg project (DiPol; homepage http://www.tu-harburg.de/iue/dipol.html), the
regional relative risk ranking analysis in Gothenburg evaluates several diffuse pollution
sources including agriculture, industry, forestry, recreation, surface water runoff, waste
water treatment plants, and maritime shipping in the area in regards to geographical
distribution and perceived risk and impact. The model combines sources, stressors,
habitats, and indicators and allows the user to rank the relationships between these. The
model output can help determine the highest at-risk regions within an area as well as the
significant sources of diffuse pollution in order to prioritize remediation or mitigation
measures. Our analysis focuses on the rivers and streams in Gothenburg, specifically
looking at the Göta älv River, and the tributary streams Säve ån, Mölndals ån,
Kvillebäcken, as well as the estuary at the mouth of Göta älv River. The highest risk to
the indicators (bathing water quality, environmental water quality, and sediment quality)
is suggested to be largely dependent on which region one looked at, but the highest
relative risk is associated with surface water runoff, industry, and agriculture. However,
the estuary is more highly affected by discharges from the city waste water treatment
plant.

As a decision-making tool, these results need to be evaluated with cost benefit and
stakeholder concerns. In this project, a system analysis (“Sensitivity model”) was
carried out to make these connections and to highlight the possible mitigation
alternatives. In addition, GIS models for contaminant fluxes and site-specific loading
along the urban waterways are used to complement the conclusions from relative risk
ranking to balance, for instance, the use of local infiltration, treatment and direct
discharge of surface runoff, one of the main sources of diffuse pollution. These models
and quantitative assessments illustrate an integration of scientific and end-user
perspectives, especially important for complex urban systems.

Keywords: urban pollution, risk ranking, waterways, Sweden, modeling