Rethinking Infrastructure Design - Rethinking Infrastructure Design for Multi-Use Water Services - page 4

urban imbalance lie, among others, at the neighbourhood level. Applying a more
natural approach to water management, for instance with thorough use of natural
out

ltration into the soil, better utilisation
of rainwater reuse of wastewater in due time and improved urban planning, which
incorporates local characteristics into the management plan will be more cost-
effective and ef

ows or buffering, more use of on-site in

cient in comparison to centralised water management. Since the
centralised systems are based on arti cial balance of urban water, they are

becoming increasingly unbalanced and vulnerable to increasing urbanisation and
climate change.

2 Climate Change

The most common weather (climate) variables impacting the urban environment are
air temperature, precipitation (rainfall) and water level in the seas and rivers. Being
stochastic in nature, they are characterised by trends in their mean value and
extremes represented by standard deviation. As shown in Fig. 3 , there is no
agreement in the long-term changes of mean values of air temperature predicting
that it may rise between 0.5 and 4

°

C. However as experienced all over the world,
extremes of both air temperature and precipitation are increasing in both magnitude
and durations, causing inter alia more severe droughts and all sorts of

oods

(pluvial, fluvial, coastal and groundwater). Multiple water usage aims at reducing

vulnerability of urban areas to these long-term climate changes and variability of
extremes.

Fig. 3 Predicted global
surface warming ( C) with

variability of extremes of
rainfall and air temperature
superimposed

°