Systems Analysis of Zaragoza Urban Water - SWITCH - Managing ...

Systems Analysis of Zaragoza UWS
Guillermo Penagos
4.4.3.5 Setting priorities for pollution loads
This report provides insights about the environmental impacts of Zaragoza UWS
operation on a year basis. However such impacts are not constant all over the year
and might vary seasonally. In fact, even if pollution loads remained constant all over
the year, there will be a seasonal variation of the receiving environment. This is more
evident for the water bodies and is remarkable for the Ebro River which exhibits an
important variation of its discharge along the year. The current hydrograph for the
Ebro river on a month average basis is provided in figure 25. This figure also shows
the worst climate change scenario expected for water availability in this basin for the
year 2020 and the year 2060.
500
Current 2020 2060
Average discharge (m 3 s -1 )
400
300
200
100
0
Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep
Month
Figure 25. Regimes for Ebro River at Zaragoza under current conditions and projected
conditions under Sc3 Scenario. Error bars represent standard deviations on a month basis (Source
for current regime: CHE, 2007)
In current conditions maximum discharges of nearly 400 m 3 s -1 are expected between
December and April. Minimum discharges are expected during summer time,
especially in August, where they can be as low as 30 m 3 s -1 . This also means that the
impact of Zaragoza UWS upon the Ebro River is not constant all over the year and it
reaches a maximum in August. Figure 26 provides an example of the seasonality of
this impact taking total phosphorus as an example.
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