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.)

Dr Tomas HoldernessGeomatics Research Fellow

tomas@uow.edu.au@iholderness