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

Systems Analysis of Zaragoza UWS
Guillermo Penagos
A likely scenario for the year 2020, considering different levels of water recycling was
analyzed here, and the probable performance of the UWS under the most negative
predictions for climate change and upstream water extraction was assessed by
means of the sustainability indicators previously presented and discussed.
According to the scenario assessed here, water from Yesa reservoir will remain
available for the city and it will be able to fulfill all requirements during the next 50
years, even under worst possible scenario for climate change and irrigation.
However, as consequence of very low volumes during summer time, coupled with
expected increased radiation and temperature there is some possibility for algal
blooms that might threaten drinking water quality in the years to come. Under this
scenario, water from Ebro River will be even more unsuitable for drinking purposes.
Therefore Zaragoza will have to completely relay on the Yesa reservoir to fulfill its
water demand.
In current conditions it seems also that ground water supply for Zaragoza is granted.
However the National Irrigation Plan that is about to be implemented has the purpose
of upgrading the existing irrigation technology to optimize water use. If increasing
evapotranspiration is also expected due to climate change (Ayala-Carcedo, 2000).
As consequence it is probable that groundwater recharge for Zaragoza will not
remain at the current rate, and the water table will probably drop down and ground
water extraction will not be as feasible as now, but this is not possible to know now
since there are no studies about groundwater recharge in this aquifer. Such studies
are urgently required and this is partially the subject of the Ebro River Working Group
(2007).
The recycling water strategy proposed here would obviously have a direct benefit
upon water withdrawal. Also a slightly positive effect is expected on energy
consumption and thereby also on CO 2 emissions to the atmosphere. No effect of this
strategy is expected on pollution loads to the Ebro River neither to agriculture soil. In
fact if population and industrial activities continue to increase, even under a reduction
of water withdrawal scenario, pollution loads to the environment are expected to
increase likewise. Therefore, with current WWT technology and societal behaviors it
will be possible to improve just some aspects of the environmental performance of
the system.
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