Daniel Navarro Bermudez

Evaluation of Sustainable Drainage Systems using a novel benefit intensity methodology

Intensive  rates  of  urbanisation  have  led  to  an  increase  of  non-­‐permeable  surfaces
altering natural hydrologic conditions. Conventional drainage solutions have been focused on “grey”
pipe solutions to remove stormwater runoff preventing flooding on site but causing several problems
downstream the catchment. Therefore, a recent approach on flood risk management strategies is the
use of Sustainable Drainage Systems (SuDS). The aim is to replicate pre-­‐development conditions
and to treat stormwater runoff on site. Current evaluation of SuDS components is mainly realised
through methods such as Multi-­‐Criteria Decision Analysis (MCDA) or Cost Benefit Analysis (CBA).
These are restricted to spreadsheets, where the complex interrelationship of variables within the
local context cannot be fully assessed. This dissertation focuses in the development of a
methodology to evaluate SuDS benefits and their spatial distribution through the use of
Geographical Information Systems (GIS). The experimental study consisted first in a literature
research to determine the parameters to assess six SuDS benefits; then a GIS-­‐based methodology
for modelling was developed to quantify their intensity and spatial distribution. A case study was
used to pilot the methodology and analyse its feasibility as an assessment tool. The findings from
this research indicate that SuDS components offer greater benefits than the conventional grey
approach. In addition, the methodology developed has a potential to assist decision-­‐makers since
it increases the accuracy of the evaluation by virtue of the incorporation of the local context.
This dissertation recommends the implementation of the methodology developed as a cornerstone in
projects’ design since it demonstrates the spatial benefit intensity of SuDS components placed on
site.  

Keywords: Sustainable Drainage Systems (SuDS); Geographical Information Systems (GIS);    SuDS    
benefits;    SuDS    assessment    methodology;    Spatial    SuDS    benefits
distribution.