Monday, 30th September 2013: Business & policy Dialogue
Tuesday 1 October to Thursday, 3rd October: Academic and PolicyDialogue
www.isngi.org
ENDORSING PARTNERS
The following are confirmed contributors to the business and policy dialogue in Sydney:
Rick Sawers (National Australia Bank)
Nick Greiner (Chairman (Infrastructure NSW)
www.isngi.org
Spatial Network Modelling for Sanitation Planning in
Informal Settlements
Presented by: Dr Tomas Holderness SMART Infrastructure Facility, University of Wollongong
KSpatial Network Modelling for Sanitation Planning in
Informal Settlements
Tomas Holderness1, Ruth Kennedy-Walker2, David Alderson2 & Barbara Evans3
1 University of Wollongong, 2 Newcastle University (UK), 3 University of Leeds (UK)
The Sanitation Infrastructure Crisis• Rapid city densification
• Peri-urbanisation growth
• Informal infrastructure
Image credits: [1] Nils Gilman/io9.com; [2] PIUS UTOMI EKPEI/AFP/Getty Images
The Sanitation Crisis
Image credits: [1] WHO/UNICEF
Critical Infrastructure?
Image credits: [1] Florian Erzinger
A “frogman” manually emptying a pit latrine in Dar es Salaam
The Solution?
Vacutug:• Vacuum pump truck• 0.5m3 capacity• 5 Km/h speed
Image credits: [1] Rémi Kaup; [2] Sustainable Sanitation Alliance
Transfer stations
Image credits: [1] Authors; [2] Tilley et al. 2008
• Reduce Vacutug travel time
• Situated at the edge of informal settlement
• Serviced by large collection tanker
• Location is key to reduce time and costs
A new approach
Image credits: [1] Map Kibera
• Crowd-sourced mapping for spatio-toplogical network modelling• Land cover, road/path network, amenity location
• Optimise location of transfer stations to minimise transport time• Iterative, weighted Dijkstra’s algorithm
• Open-source tool to support Engineers in the sanitation planning process
Methodology
Data preprocessing & spatial database
construction
MCE site analysis
Create network
Network Analysis
Data preprocessing
Image credits: [1] Google, Digital Globe
Data preprocessing
Data downloaded from Open Street Map and Map Kibera:
• Total area ~ 3000 Km2 (inc. Kibera)• 6,557 points of interest• 9,222 linear features (roads, waterways, railways etc.)• 7,800 polygon features• 582 water and sanitation features in Kibera:
• 158 public toilets• 8 bio-centres
• Data loading into PostGIS using Python (GDAL/OGR, Fiona, GeoAlchemy2)
Multi-criteria evaluation of transfer station locations
• MCE analysis implemented using PostGIS
• Transfer station location parameters:• Area ≥ 64m2
• Kibera boundary ≤ 50m• Nearest road ≤ 5m
Image credits: [1] Map Kibera
Network Creation
• Spatio-topological model created using PostGISschema and NetworkX interface
• 19,558 edges (Nairobi and Kibera)• 4,686,483 Km of road and footpath• 16,347 nodes (junctions, toilets, transfer stations,
treatment plant)
Network Analysis
Total time for shortest network path:• Each toilet to transfer station (158 trips)• Accumulated waste, transfer station to treatment (7.9 trips)
• Vacutug capacity: 500 liters• Large tanker capacity: 10,000 liters
Results
Image credits: [1] Map Kibera
Results
Image credits: [1] Google, Digital Globe
Conclusions
• Crowd-sourced map data enabling network analysis
• Spatio-topological network modelling within GIS framework useful for sanitation planning
• Limited by data quality and availability
• Next steps,• Attributing cost to networks
• Business case• Tie to sanitation value chain
• Compare against pipe sewerage network• Apply to other networks (solid waste etc.)
