URBAN HYDROLOGY

1
URBAN HYDROLOGY
2
URBAN FABRIC

• RUNOFF PROCESSES AND DRAINAGE CHANNELS

3
Hardened surface promotes rapid surface runoff
4
Runoff channeled along roadside flows rapidly
downhill
5
Many streams in urban areas are at least
partially channelised
6
The Kuils River on the Cape Flats is typical of
urban channels
7
URBAN STRUCTURE

• RUNOFF SURFACES AND DRAINAGE NETWORKS

8
Panorama of Grahamstown note proportion of
hardened v. vegetated surfaces and degree of
connectivity between runoff surfaces and the
main stream channel.
9
(No Transcript)
10
How does the hydrological response change in
different areas of the town?
11
Riparian zone of Blaukrantz river how connected
is the river to the build up area?
12
Upper catchment of small urban stream
13
POLLUTION SOURCES
14
Litter in an urban stream pollution derived from
the catchment surface
15
Sewage works below King Willliamstown and
Zwelitscha Note Buffalo River in trees to the
left of the sewage ponds.
16
Saline outflow from the Da Gama textile factory
17
DOWNSTREAM IMPACTS
18
Algal growth in Laing Dam
19
Water hyacinth in Laing Dam
20
FLOOD PLAIN TRANSFORMATION
21
The modern flood plain of the Ebro River,
northern Spain
22
Zaragoza town in early days impact on river
channel and flood plain is localised
23
Modern Zaragoza impacts now extensive
24
Flood walls protect urban development
25
REGIONAL IMPACTS
26
Gareip dam source of water for Port Elizabeth
and Grahamstown
27
WATER SUPPLY TO GRAHAMSTOWN