Mass balances identify the main sources and sinks of the studied variables and quantify export lo... more Mass balances identify the main sources and sinks of the studied variables and quantify export loads and environmental pollution induced by irrigated agriculture. Salt and nitrogen mass balances were performed in La Violada irrigation district (VID) along the irrigation seasons (April to September) of the 80's (1982 to 1984), 90's (1995 to 1998) and 00's (2005). The 5282-ha VID is located in the middle Ebro River Basin (north-east Spain) and has about 3800 flood-irrigated ha. The main sources and sinks of water, salts and nitrogen were measured or estimated in VID during these irrigated seasons (volumes of irrigation, precipitation, crop's evapotranspiration and drainage at La Violada gully D-14 station, the outlet of VID; salt and nitrate concentrations and loads in the water flows; N applied with fertilizers). Salt (TDS) and nitrate (NO 3 ) concentrations and export loads from VID along the 80's, 90's and 00's decades were compared with the observed changes in crops and in irrigation and nitrogen fertilization management. District's irrigation efficiency increased from 40% in the 80's to 50% in the 90's and 62% in 2005 (a severe water-shortage year with a 60% decrease in irrigation and with an intensive reuse of irrigation drainage water). Seasonal TDS at D-14 were relatively steady, but somewhat higher in 2005 (2140 mg/L) than in the 80's (1987 mg/L) and 90's (1727 mg/L). The 2005 increases in TDS were moderated by the gypsiferous composition of the drainage waters. Salt load exports at D-14 were controlled mainly by the D-14 gully flows (Q), more variable than the TDS. Hence, salt exports were high in the 80's (13,1 Mg/ha) and 90's (14,5 Mg/ha) and much lower in 2005 (5,1 Mg/ha). Seasonal NO 3 concentrations and N loads at D-14 showed an upward trend along the 1987-1998 period (NO 3 from 26 to 62 mg/L and N loads from 47 to 122 kg N/ha). These values were much lower in the atypical 2005 year (20,8 mg/L and 11,4 kg N/ha) because of the combination of a low corn acreage, a low irrigation water application and an intensive reuse of irrigation drainage water. Seasonal N loads were correlated with the acreage cropped to corn, so that each 100ha increase in corn acreage will increase the N export loads by 3,3 kg N/ha. We concluded that the presently VID high off-site salt and nitrate pollution could be reduced through: (1) a more efficient irrigation management (increased flexibility in water distribution and allocation by constructing internal regulatory reservoirs, changes to pressurized systems in areas with low water-holding capacity soils, reducing the post-sowing irrigations given to corn to enhance its stand establishment), (2) a more efficient N fertilization management (reducing the June and July side-dress N applications given to corn) and (3) increasing the reuse for irrigation of the relatively low-EC, high-NO 3 La Violada gully waters.
The analysis of long-term irrigation performance series is a valuable tool to improve irrigation ... more The analysis of long-term irrigation performance series is a valuable tool to improve irrigation management and efficiency. This work focuses in the assessment of irrigation performance indices along years 1995 to 2008, and the cause-effect relationships with irrigation modernization works taking place in the 4000 ha surface-irrigated La Violada Irrigation District (VID). Irrigation management was poor, as shown by the low mean seasonal irrigation consumptive use coefficient (ICUC = 51%) and the high relative water deficit (RWD = 20%) and drainage fraction (DRF = 54%). April had the poorest irrigation performance because corn (with low water demand in this month) was irrigated to promote its emergence, whereas winter grains (with high water demands in this month) were not fully irrigated in water-scarce years. Corn, highly sensitive to water stress, was the crop with best irrigation performance because it was preferentially irrigated to minimize yield losses. The construction of a new elevated canal that 2 decreased seepage and drainage fractions, the entrance in operation of six internal reservoirs that would increase irrigation scheduling flexibility, and the on-going transformation from surface to sprinkler irrigation systems are critical changes in VID that should lead to improved ICUC, lower RWD and lower DRF. The implications of these modernization works on the conservation of water quantity and quality within and outside VID is further discussed.
The analysis of long-term irrigation performance series is a valuable tool to improve irrigation ... more The analysis of long-term irrigation performance series is a valuable tool to improve irrigation management and efficiency. This work focuses in the assessment of irrigation performance indices along years 1995 to 2008, and the cause-effect relationships with irrigation modernization works taking place in the 4000 ha surface-irrigated La Violada Irrigation District (VID). Irrigation management was poor, as shown by the low mean seasonal irrigation consumptive use coefficient (ICUC = 51%) and the high relative water deficit (RWD = 20%) and drainage fraction (DRF = 54%). April had the poorest irrigation performance because corn (with low water demand in this month) was irrigated to promote its emergence, whereas winter grains (with high water demands in this month) were not fully irrigated in water-scarce years. Corn, highly sensitive to water stress, was the crop with best irrigation performance because it was preferentially irrigated to minimize yield losses. The construction of a new elevated canal that 2 decreased seepage and drainage fractions, the entrance in operation of six internal reservoirs that would increase irrigation scheduling flexibility, and the on-going transformation from surface to sprinkler irrigation systems are critical changes in VID that should lead to improved ICUC, lower RWD and lower DRF. The implications of these modernization works on the conservation of water quantity and quality within and outside VID is further discussed.
Mon o graf ia a p re se nt ad a a Un ive rsid a de Est ad u a l do No rte d o P a ra n á -UE NP -... more Mon o graf ia a p re se nt ad a a Un ive rsid a de Est ad u a l do No rte d o P a ra n á -UE NP -Cen t ro de Ciên cia s Hum an a s e d a E du ca çã o -CCHE / CJ, Cu rso d e Filo sof ia , com o re qu isit o pa rcia l pa ra o bt en çã o do t ít u lo d e lice n ciad o em Filo sof ia . O rien t a çã o : P ro f . Dr. Ma u ricio G on ça lve s S a lib a
Mass balances identify the main sources and sinks of the studied variables and quantify export lo... more Mass balances identify the main sources and sinks of the studied variables and quantify export loads and environmental pollution induced by irrigated agriculture. Salt and nitrogen mass balances were performed in La Violada irrigation district (VID) along the irrigation seasons (April to September) of the 80's (1982 to 1984), 90's (1995 to 1998) and 00's (2005). The 5282-ha VID is located in the middle Ebro River Basin (north-east Spain) and has about 3800 flood-irrigated ha. The main sources and sinks of water, salts and nitrogen were measured or estimated in VID during these irrigated seasons (volumes of irrigation, precipitation, crop's evapotranspiration and drainage at La Violada gully D-14 station, the outlet of VID; salt and nitrate concentrations and loads in the water flows; N applied with fertilizers). Salt (TDS) and nitrate (NO 3 ) concentrations and export loads from VID along the 80's, 90's and 00's decades were compared with the observed changes in crops and in irrigation and nitrogen fertilization management. District's irrigation efficiency increased from 40% in the 80's to 50% in the 90's and 62% in 2005 (a severe water-shortage year with a 60% decrease in irrigation and with an intensive reuse of irrigation drainage water). Seasonal TDS at D-14 were relatively steady, but somewhat higher in 2005 (2140 mg/L) than in the 80's (1987 mg/L) and 90's (1727 mg/L). The 2005 increases in TDS were moderated by the gypsiferous composition of the drainage waters. Salt load exports at D-14 were controlled mainly by the D-14 gully flows (Q), more variable than the TDS. Hence, salt exports were high in the 80's (13,1 Mg/ha) and 90's (14,5 Mg/ha) and much lower in 2005 (5,1 Mg/ha). Seasonal NO 3 concentrations and N loads at D-14 showed an upward trend along the 1987-1998 period (NO 3 from 26 to 62 mg/L and N loads from 47 to 122 kg N/ha). These values were much lower in the atypical 2005 year (20,8 mg/L and 11,4 kg N/ha) because of the combination of a low corn acreage, a low irrigation water application and an intensive reuse of irrigation drainage water. Seasonal N loads were correlated with the acreage cropped to corn, so that each 100ha increase in corn acreage will increase the N export loads by 3,3 kg N/ha. We concluded that the presently VID high off-site salt and nitrate pollution could be reduced through: (1) a more efficient irrigation management (increased flexibility in water distribution and allocation by constructing internal regulatory reservoirs, changes to pressurized systems in areas with low water-holding capacity soils, reducing the post-sowing irrigations given to corn to enhance its stand establishment), (2) a more efficient N fertilization management (reducing the June and July side-dress N applications given to corn) and (3) increasing the reuse for irrigation of the relatively low-EC, high-NO 3 La Violada gully waters.
The analysis of long-term irrigation performance series is a valuable tool to improve irrigation ... more The analysis of long-term irrigation performance series is a valuable tool to improve irrigation management and efficiency. This work focuses in the assessment of irrigation performance indices along years 1995 to 2008, and the cause-effect relationships with irrigation modernization works taking place in the 4000 ha surface-irrigated La Violada Irrigation District (VID). Irrigation management was poor, as shown by the low mean seasonal irrigation consumptive use coefficient (ICUC = 51%) and the high relative water deficit (RWD = 20%) and drainage fraction (DRF = 54%). April had the poorest irrigation performance because corn (with low water demand in this month) was irrigated to promote its emergence, whereas winter grains (with high water demands in this month) were not fully irrigated in water-scarce years. Corn, highly sensitive to water stress, was the crop with best irrigation performance because it was preferentially irrigated to minimize yield losses. The construction of a new elevated canal that 2 decreased seepage and drainage fractions, the entrance in operation of six internal reservoirs that would increase irrigation scheduling flexibility, and the on-going transformation from surface to sprinkler irrigation systems are critical changes in VID that should lead to improved ICUC, lower RWD and lower DRF. The implications of these modernization works on the conservation of water quantity and quality within and outside VID is further discussed.
The analysis of long-term irrigation performance series is a valuable tool to improve irrigation ... more The analysis of long-term irrigation performance series is a valuable tool to improve irrigation management and efficiency. This work focuses in the assessment of irrigation performance indices along years 1995 to 2008, and the cause-effect relationships with irrigation modernization works taking place in the 4000 ha surface-irrigated La Violada Irrigation District (VID). Irrigation management was poor, as shown by the low mean seasonal irrigation consumptive use coefficient (ICUC = 51%) and the high relative water deficit (RWD = 20%) and drainage fraction (DRF = 54%). April had the poorest irrigation performance because corn (with low water demand in this month) was irrigated to promote its emergence, whereas winter grains (with high water demands in this month) were not fully irrigated in water-scarce years. Corn, highly sensitive to water stress, was the crop with best irrigation performance because it was preferentially irrigated to minimize yield losses. The construction of a new elevated canal that 2 decreased seepage and drainage fractions, the entrance in operation of six internal reservoirs that would increase irrigation scheduling flexibility, and the on-going transformation from surface to sprinkler irrigation systems are critical changes in VID that should lead to improved ICUC, lower RWD and lower DRF. The implications of these modernization works on the conservation of water quantity and quality within and outside VID is further discussed.
Mon o graf ia a p re se nt ad a a Un ive rsid a de Est ad u a l do No rte d o P a ra n á -UE NP -... more Mon o graf ia a p re se nt ad a a Un ive rsid a de Est ad u a l do No rte d o P a ra n á -UE NP -Cen t ro de Ciên cia s Hum an a s e d a E du ca çã o -CCHE / CJ, Cu rso d e Filo sof ia , com o re qu isit o pa rcia l pa ra o bt en çã o do t ít u lo d e lice n ciad o em Filo sof ia . O rien t a çã o : P ro f . Dr. Ma u ricio G on ça lve s S a lib a
Uploads
Papers by Rafael Barros