7This study analyzes the effects of irrigation modernization on water conservation, using 8 the Riegos del Alto Aragón (RAA) irrigation project (NE Spain, 123.354

No abstract

An analysis of the spatial and temporal patterns of global burned area with the Daily Tile US National Oceanic and Atmospheric Administration-Advanced Very High-Resolution Radiometer Pathfinder 8 km Land dataset between 1981 and 2000 is presented. Nine distinct temporal and spatial fire patterns were identified at the global scale using principal components and cluster analysis. Three major fire seasons were identified from June to December and from February to June for different areas of the northern hemisphere and from October to March for the southern hemisphere. The area burned primarily followed the annual cycle and secondarily, an important 6-month cycle. Temporal cycles were unimportant in some equatorial and tropical areas in the northern hemisphere. The total annual burned area has not increased in the last 20 years but a significant increase was found in the mid-latitude and subtropical areas of the northern hemisphere which was offset by a slight decrease in burned area in tropical southeast Asia and Central America. Additionally, burned area has significantly increased during the summer in the mid-latitudes of the northern hemisphere and in the boreal region, and the fire season starts earlier in the midlatitudes. Total burned area was explained by the extent of savanna (wooded grassland) cover. Latitude was not determinative as divergent fire patterns were encountered and did not have an impact on extent of burned area at our spatial level of analysis. Nomenclature:ARIMA 5 autoregressive integrated moving average AVHRR 5 Advanced Very High-Resolution Radiometer CL 5 cluster group GAC 5 NOAA-AVHRR global area coverage MODIS 5 moderate resolution imaging spectrometer n 5 number of cases for each specific analysis NOAA 5 US National Oceanic and Atmospheric Administration P 5 probability of a significant trend PAL 5 NOAA-AVHRR Pathfinder Land 8-km land dataset PC 5 principal component Q 5 Mann-Kendall seasonal nonparametric estimator of slope SD 5 standard deviation SE 5 standard error

The surface Irrigated District V of the Bardenas Canal (Zaragoza, Spain)

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.

9Long-term analysis of hydrologic series in irrigated areas allows identifying the main 10 water balance components, minimizing closing errors and assessing changes in the 11 hydrologic regime. The main water inputs [irrigation (I) and precipitation (P)] and 12 outputs [outflow (Q) and potential (ET c ) crop evapotranspiration] in the 4000-ha La 13Violada irrigation district (VID) (Ebro River Basin, Spain) were measured or estimated 14 from 1995 to 2008. A first-step, simplified water balance assuming steady state 15 conditions (with error ε = I + P -Q -ET c ) showed that inputs were much lower than 16 outputs in all years (average ε = -577 mm/yr or -33% closing error). A second-step, 17 improved water balance with the inclusion of other inputs (municipal waste waters, 18 canal releases and lateral surface runoff) and the estimation of crop's actual 19 evapotranspiration (ET a ) through a daily soil water balance reduced the average closing 20 error to -13%. Since errors were always higher during the irrigated periods, when canals 21 are full of water, a third-step, final water balance considered canal seepage (CS) as an 22 additional input. The change in water storage in the system (∆W) was also included in 23 this step. CS and ∆W were estimated through a monthly soil-aquifer water balance, 24 2 showing that CS was a significant component in VID. With the inclusion of CS and ∆W 1 in the water balance equation, the 1998-2008 annual closing errors were within ±10% of 2 total water outputs. This long-term, sequential water balance analysis in VID was an 3 appropriate approach to accurately identify and quantify the most important water 4 balance components while minimizing water balance closing errors. 5

Simulated annual values were in general more accurate than simulated monthly values. 13 APEX predicted that improving irrigation management (change of irrigation system 14 and/or scheduling) will decrease N loads in IRF over current values by 45% (Akarsu), 15 40% (La Violada), and 8% (Sidi Rached). However, improved N fertilization only will 16 reduce N loads in IRF by 17% (Akarsu) or below 5% (La Violada and Sidi Rached). 17Improving irrigation management will increase IRF NO 3 -N concentrations by 19% in La 18 Violada and will decrease or will remain the same in the other two watersheds. APEX 19 simulations identified the main soils (shallow and low water holding capacity soils) and 20 crops (heavily fertilized or shallow-root crops) N polluters within the studied watersheds. 21Overall, APEX simulated that the improvement of irrigation performance was the best 22 management strategy to decrease off-site N pollution while maintaining or increasing crop 23 yields in the three studied Mediterranean watersheds. 24

Fertilizer leaching affects farm profitability and contributes to nonpoint-source pollution of receiving waters. This work aimed to establish nitrate nitrogen export from La Violada Gully in relation to nitrogen fertilization practices in its basin (La Violada Gully watershed, VGW, 19,637 ha) and especially in La Violada Irrigation District (VID, 5282 ha). Nitrogen (N) fertilization in VID (and VGW) was determined through interviews with local farmers for the hydrologic years 1995 and 1996 and NO3-N load in the gully was monitored from 1995 to 1998. The N fertilizer applied in VGW was 2175 Mg in 1995 and 2795 Mg in 1996. About 43% was applied in VID (945 Mg in 1995 and 1161 Mg in 1996). The most fertilized crop was corn: 398 kg N ha-1 (665 Mg) in 1995 and 453 kg N ha-1 (911 Mg) in 1996. Nitrogen fertilization was higher than N uptake for irrigated crops, especially for corn and rice. Nitrate N load in La Violada Gully averaged 427.4 Mg yr-1. Seventy-five percent of the exports took place during the irrigation season (321.8 Mg). During the non-irrigation season maximum NO3-N loads (3.1 Mg NO3-N d-1) were found after heavy rains following the N side-dressing of wheat in the rain-fed area of VGW (February). During the irrigation season NO3-N load was determined by outflow from the district (caused by irrigation) and to a lesser extent by changes in NO3 concentration (caused by fertilization), showing peaks in April (pre-sowing corn N fertilization and first irrigations) and June to August (highest irrigation months and corn side-dress N applications, maximum 6.3 Mg NO3-N d-1 in July). Adjusting N fertilization to crops' needs, improving irrigation efficiencies, and better scheduling N fertilization and irrigation in corn could reduce N export from VID.