poster - International Conference of Agricultural Engineering
poster - International Conference of Agricultural Engineering poster - International Conference of Agricultural Engineering
3. Results 3.1. Effects of SSCCs on physical parameters Water temperature For uncovered AWRs, the thermal behaviour was discovered almost isothermal whereas for covered ones, water experienced some thermal stratification during the warmer months (Fig. 1). Tw (ºC) 30 26 22 18 14 a: C 1 0.2 m 0.5 m 1.5 m 2.5 m 3.5 m 4.5 m Covered (C1 0,2) Covered (C1 0,5) Covered (C1 1,5) Covered (C1 2,5) Covered (C1 3,5) Covered (C1 4,5) Tw (ºC) 30 26 22 18 14 b: C 2 0.2 m 0.5 m 1.5 m 2.5 m 3.5 m 4.5 m Covered (C2 0,2) Covered (C2 0,5) Covered (C2 1,5) Covered (C2 2,5) Covered (C2 3,5) Covered (C2 4,5) 10 10 6 Mar-11 May-11 30 c: U 1 26 Jul-11 Sep-11 Nov-11 Jn-12 Jan-12 Mar-12 Uncovered (B1) 6 Mar-11 May-11 30 d: U 2 26 Jul-11 Sep-11 Nov-11 Jn-12 Jan-12 Mar-12 Uncovered (B2) Tw (ºC) 22 18 14 Tw (ºC) 22 18 14 10 6 Mar-11 May-11 Jul-11 Sep-11 Nov-11 Jn-12 Jan-12 Mar-12 FIGURE 1: Changes in water temperature (T w ) in covered (a) C 1 , (b) C 2 and uncovered (c) U 1 and (d) U 2 AWRs during the one-year experimentation period. Charts a and b show T w at different depths in the AWR whereas charts c and d present the average value of T w at all depths. The discontinuities observed in the curves of the charts a and b (covered AWRs) represent periods in which the reservoirs did not store water at that depth. In Uncovered AWRs, T w was affected by the short-wave radiation that shone through the water profile and the incoming and outcoming long-wave radiation at the water surface, whereas for covered ones, T w was affected by the long-wave radiation emitted by the SSCC (recorded maximum cover temperature of 60ºC at midday in summer) that did not shone through the water profile, hence heating the shallowest layers. Besides, other input and output energy fluxes that varied T w in both uncovered and covered AWRs were based on the regulation for irrigation function of the reservoir (water that enters and leaves the reservoir). However, such term was important only in covered AWRs, since the temperature of inlet water (water in the Tajo-Segura aqueduct) was always a few degrees higher than the temperature of the stored water. Such mentioned different thermal behaviour between uncovered and covered AWRs together with the wind effect on 10 6 Mar-11 May-11 May-11 Jul-11 Sep-11 Nov-11 Jn-12 Jan-12 Mar-12 3
uncovered ones, that mixed the water layers, led covered AWRs to present a slight thermal gradient during the warmer months (maximum of 2ºC in September). The thermal gradient disappeared in the fall, when the first autumn rain cooled the upper layer inducing thermal mixing in the water. Such small thermal gradient registered on covered reservoirs does not match the results reported by Maestre-Valero et al. (2011) who observed a thermal gradient of 12ºC between the deeper and surface layers in water reservoirs no-regulated for irrigation. The use of reservoirs for irrigation, which implied the inlet and outlet of water and therefore a short time of permanence of the water in the AWR, was likely to soften the effect of the installation of the cover on the water thermal stratification. Electrical conductivity Unlike what happens in AWRs without regulation (Maestre-Valero et al., 2011), in this study, where AWRs were used for irrigation, changes in the EC are the result of a water and salt balance that involves both the water entries as storing and rainfall and the outputs as water used for irrigation and evaporation. Martínez-Alvarez et al. (2009) indicated that for an uncovered reservoir of about 12,000 m 3 which supplies an area of about 4 ha, the volume of water evaporated and rainfall with respect to the regulated water volume was 14.2% and 2.8% respectively. Such values for the same AWR in covered conditions were about 4.0%. Accordingly, those low percentages indicate that in regulated AWRs, evaporation and rainfall play a minor role in EC reductions; being EC changes mainly due to water renewals. Chlorophyll-a (Algae) In covered AWRs, the cover did not allow the proliferation of algae and hence Chl-a was rather low during the experimental period (< 1 μg L -1 ). For uncovered AWRs, however, the incidence of the solar radiation in the water favoured the photosynthesis processes and hence the algae proliferation. A significant difference in algae concentration was also found between uncovered AWRs U 1 and U 2 . Water in U 1 remained stagnant for longer periods and renewals were also less frequent. U 1 reached a maximum of Chl-a of 52 μg L -1 . U 2 renewed water more frequently only reaching a maximum of 25 μg L -1 . For both uncovered AWRs, maximums of Chl-a were reached in September when the climatic conditions for algae growth were more suitable. W t followed the Chl-a trend during the experimental period. Dissolved oxygen Maestre-Valero et al. (2011) manifested that the oxygen concentration in the stored water in an AWR not used for irrigation was almost completely depleted in about two months after installing a SSCC. Unlike what happens with DO in that kind of AWRs, DO in covered AWRs with regulation for irrigation, where there is a short time of permanence of the water in the AWR, remained close to saturation during the whole experimentation period (Fig. 2). Renewals of water in covered AWRs increased the DO concentration, having this factor a more important effect in the DO concentration than the reduction of DO by the installation of the SSCC. DO in uncovered AWRs was slightly higher than DO in covered AWRs. The continuous renewals of water and the oxygation process by oxygen diffusion on the surface water and generation by photosynthesis allowed reaching such higher DO concentrations. 3.2. Effects of SSCCs on chemical parameters The determination of chemical parameters of water for irrigation is of substantial importance. For instance, Na + , B + and Cl - are toxic to plants and in addition, high concentration of Na + - 2- may cause problems of permeability in the soil. NO 3 and SO 4 are on the one hand, a natural source of nutrients for plants but, instead, present a risk of water eutrophication that can lead to a risk of clogging drip emitters during the irrigation. Covering AWRs hardly had consequences in the chemical water quality parameters and statistical analyses indicated 4
- Page 27 and 28: Figure1 - Relationship between the
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- Page 39 and 40: Cool, J. B., Rodrigo, G. N., Garcí
- Page 41 and 42: Abstract Agriculture and water sour
- Page 43 and 44: In 1985 and 1986 hygienic protectio
- Page 45 and 46: spring area. It is also prohibited
- Page 47 and 48: Biological Nitrogen Fixation In Gen
- Page 49 and 50: We used a completely randomized in
- Page 51 and 52: 5. References AYERS, R.S.; WESTCOT,
- Page 53 and 54: 2 However, the cultures are not alw
- Page 55 and 56: 4 TABEL 2: Mean values of radiation
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- Page 71 and 72: Table 2. Daily affluent concentrati
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- Page 99 and 100: higher demand than those of scenari
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- Page 107 and 108: SUGARCANE FERTIRRIGATED WITH MINERA
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- Page 111 and 112: espectively, compared to that obser
- Page 113 and 114: Optimal Reservoir Operation Model w
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3. Results<br />
3.1. Effects <strong>of</strong> SSCCs on physical parameters<br />
Water temperature<br />
For uncovered AWRs, the thermal behaviour was discovered almost isothermal whereas for<br />
covered ones, water experienced some thermal stratification during the warmer months (Fig.<br />
1).<br />
Tw (ºC)<br />
30<br />
26<br />
22<br />
18<br />
14<br />
a: C 1<br />
0.2 m<br />
0.5 m<br />
1.5 m<br />
2.5 m<br />
3.5 m<br />
4.5 m<br />
Covered (C1 0,2)<br />
Covered (C1 0,5)<br />
Covered (C1 1,5)<br />
Covered (C1 2,5)<br />
Covered (C1 3,5)<br />
Covered (C1 4,5)<br />
Tw (ºC)<br />
30<br />
26<br />
22<br />
18<br />
14<br />
b: C 2<br />
0.2 m<br />
0.5 m<br />
1.5 m<br />
2.5 m<br />
3.5 m<br />
4.5 m<br />
Covered (C2 0,2)<br />
Covered (C2 0,5)<br />
Covered (C2 1,5)<br />
Covered (C2 2,5)<br />
Covered (C2 3,5)<br />
Covered (C2 4,5)<br />
10<br />
10<br />
6<br />
Mar-11<br />
May-11<br />
30<br />
c: U 1<br />
26<br />
Jul-11<br />
Sep-11<br />
Nov-11<br />
Jn-12 Jan-12<br />
Mar-12<br />
Uncovered (B1)<br />
6<br />
Mar-11<br />
May-11<br />
30<br />
d: U 2<br />
26<br />
Jul-11<br />
Sep-11<br />
Nov-11<br />
Jn-12 Jan-12<br />
Mar-12<br />
Uncovered (B2)<br />
Tw (ºC)<br />
22<br />
18<br />
14<br />
Tw (ºC)<br />
22<br />
18<br />
14<br />
10<br />
6<br />
Mar-11<br />
May-11<br />
Jul-11<br />
Sep-11<br />
Nov-11<br />
Jn-12 Jan-12<br />
Mar-12<br />
FIGURE 1: Changes in water temperature (T w ) in covered (a) C 1 , (b) C 2 and uncovered (c)<br />
U 1 and (d) U 2 AWRs during the one-year experimentation period. Charts a and b show T w at<br />
different depths in the AWR whereas charts c and d present the average value <strong>of</strong> T w at all<br />
depths. The discontinuities observed in the curves <strong>of</strong> the charts a and b (covered AWRs)<br />
represent periods in which the reservoirs did not store water at that depth.<br />
In Uncovered AWRs, T w was affected by the short-wave radiation that shone through the<br />
water pr<strong>of</strong>ile and the incoming and outcoming long-wave radiation at the water surface,<br />
whereas for covered ones, T w was affected by the long-wave radiation emitted by the SSCC<br />
(recorded maximum cover temperature <strong>of</strong> 60ºC at midday in summer) that did not shone<br />
through the water pr<strong>of</strong>ile, hence heating the shallowest layers.<br />
Besides, other input and output energy fluxes that varied T w in both uncovered and covered<br />
AWRs were based on the regulation for irrigation function <strong>of</strong> the reservoir (water that enters<br />
and leaves the reservoir). However, such term was important only in covered AWRs, since<br />
the temperature <strong>of</strong> inlet water (water in the Tajo-Segura aqueduct) was always a few<br />
degrees higher than the temperature <strong>of</strong> the stored water. Such mentioned different thermal<br />
behaviour between uncovered and covered AWRs together with the wind effect on<br />
10<br />
6<br />
Mar-11<br />
May-11<br />
May-11<br />
Jul-11<br />
Sep-11<br />
Nov-11<br />
Jn-12 Jan-12<br />
Mar-12<br />
3
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