poster - International Conference of Agricultural Engineering

that there were not significant differences between uncovered and covered reservoirs, except
for NO 3 - where significant differences were found in C 2 .
Dissolved oxygen (mg l -1 )
16
12
8
4
UB1
1
UB2
2
C1
1
C2
2
0
Mar-11
May-11
Jul-11
Sep-11
FIGURE 2: Changes in dissolved oxygen (DO) for the four AWRs during the one-year
experimentation period. DO data are presented as the average of readings taken at all
depths, as there was no significant variation with depth.
Nov-11
Jn-12 Jan-12
Mar-12
3.3. Effects of SSCCs on microbiological parameters
Throughout the one-year experimental period, the uncovered AWRs showed higher
concentrations of fecal coliforms and E-coli than covered ones (reduction of 82% between
uncovered and covered AWRs). The maximum concentration of fecal coliforms and E-coli in
uncovered AWRs was found during the summer months, when the microbiological activity
was higher as a result of a high water temperature. Even during this period, E-Coli
concentration did not exceed the thresholds listed in the Royal Decree 1620/2007.
4. Conclusions
Covered AWRs for irrigation show a slight thermal gradient, which is rather different from
that observed in no-regulated covered AWRs. Variations in the EC are mainly due to water
renewals for irrigation. The installation of the cover limits the incidence of solar radiation,
reducing the algae growth and the frequent renewals of water for irrigation are not able
to increase the concentration of Chl-a. Uncovered AWRs present a significant algae growth
during the warmer months. Dissolved oxygen concentration in uncovered AWRs is slightly
higher than the DO in covered ones, although both values are next to saturation during the
experimentation. Chemical parameters are not affected by the installation of the cover. In
covered AWRs, microbiological parameters were significantly reduced since the lower water
temperature in covered AWRs hinders the development of microorganisms.
In short, the installation of SSCCs on AWRs improves water quality, but in general their
effects are smoothed as a result of frequent water renewals for irrigation. In spite of this, the
water quality changes associated with the installation of SSCCs offer many advantages for
drip irrigation. The reduction in suspended particles reduces filtering requirements and the
risk of emitter clogging, significantly improving water and energy use efficiency especially
when low quality water is stored. Besides, the cover reduces the concentration of fecal
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