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25 Pags.- 6 Figs.- 2 Tabls. The definitive version is available at: http://www.sciencedirect.com/science/journal/03783774, Accumulated daily crop evapotranspiration (ETc) generally provides good estimates of cumulative soil water depletion between irrigation of well drained soils. If the canopy is wet due to fog, dew, or light rainfall, however, energy contribution to surface evaporation will reduce transpiration and hence soil water losses. When surface evaporation occurs, the ETc overestimates the soil water depletion by an amount approximately equal to the surface water evaporation. Moratiel et al. (2013) proposed a method to estimate the contribution of surface water to ETc based on the time of canopy drying. The first method assessment was done with California data, and this evaluation was conducted in the Ebro basin, Spain, to appraise the method in a higher latitude in area with a somewhat different climate. Differences between the California and Spain corrected models were less than 10% and depended mainly on the time of canopy drying. The comparison showed that the model is robust and useful to estimate the fraction (F) of ETc coming from the soil under dew, light rainfall, and fog conditions., Thanks are due to Ministry of Agriculture, Food and Environment for facilitating data collection.

44 Pags., 5 Tabls., 5 Figs. The definitive version is available at: http://www.sciencedirect.com/science/journal/00221694, Surface renewal (SR) analysis is an interesting alternative to eddy covariance (EC) flux measurements. We have applied two recent SR approaches, with different theoretical background, that from Castellví (2004), SRCas, and that from Shapland et al. (2012a, 2012b), SRShap. We have applied both models for sensible (H) and latent (LE) heat flux estimation over heterogeneous crop surfaces. For this, EC equipments, including a sonic anemometer CSAT3 and a krypton hygrometer KH20, were located in two zones of drip irrigated orchards of late and early maturing peaches. The measurement period was June to September 2009. The SRCas is based on similarity concepts for independent estimation of the calibration factor (, which varies with respect to the atmospheric stability. The SRShap is based on analysis of different ramp-dimensions, separating the ones that are flux-bearing from the others that are isotropic. According to the results obtained here, there was a high agreement between the 30-min turbulent fluxes independently derived by EC and SRCas. The SRShap agreement with EC was slightly lower. Estimation of fluxes determined by SRCas resulted in higher values (around 11% for LE) with respect to EC, similarly to previously published works over homogeneous canopies. In terms of evapotranspiration, the root mean square error (RMSE) between EC and SR was only 0.07 mm h-1 (for SRCas) and 0.11 mm h-1 (for SRshap) for both measuring spots. According to the energy balance closure, the SRCas method was as reliable as the EC in estimating the turbulent fluxes related to irrigated agriculture and watershed distribution management, even when applied in heterogeneous cropping systems., Ground cover fraction (GCF) is defined as the fraction of ground beneath the canopy covered or shaded by a crop near solar noon as observed from directly overhead. GCF is a useful variable that can be determined in a variety of experimental procedures performed at a field plot scale. GCF is usually measured in experimental field plots using ceptometers or digital imagery. The use of these techniques in the field requires the presence in situ of qualified workers and do not permit the continuous recording of GCF. Thus, only a small number of measured values of GCF are available along the season. A network of pyranometers located at the ground level and above canopy can be connected to a datalogger so a continuous series of global radiation values can be recorded for long periods of time without the presence of any staff. Continuous values of daily GCF can be worked out from those readings. This approach could be particularly useful at remote, unattended sites. Nevertheless, the feasibility of such measures must be evaluated as the main constraint is that the pyranometers must be placed nearby the plant rows to avoid possible damage by the machinery used in the farm. This work presents the daily GCF estimates from pyranometer readings (‘pyranometer‐driven’ method, GCFpyr) at two experiments: a) Experiment I, at a table grape grown under a net, from February 2007 to November 2009; b) Experiment II, at a late peach orchard, from May to September 2011. In the Experiment II measurements were taken for one full irrigated, ‘control’ tree and for one ‘deficit irrigation’ tree., The daily GCFpyr values were compared to measured values (‘reference’ method, GCFref) using either photographical techniques (table grape) or ceptometers (late peach). For computation of GCFpyr, solar radiation below and above the canopy was averaged for two time periods: a) two hours around solar noon; b) daytime period (8:00 to 18:00 Universal Time Coordinated, UTC). For both experiments, the results obtained with the ‘pyranometer‐driven’ method improved when the solar radiation was averaged for daytime periods. For the table grape vineyard (daytime averaging period), the ‘pyranometer‐driven’ method showed a good agreement with the GCFref values as shown by a mean estimation error (MEE) of 0.000, a root mean square error (RMSE) of 0.113, and an index of agreement (IA) of 0.967. For the peach orchard (daytime averaging period), the agreement of the ‘pyranometer‐driven’ method with the GCFref values was worse, particularly with the ‘deficit irrigation’ tree. MEE was 0.046 to 0.210, RMSE was 0.064 to 0.217, and IA was 0.863 to 0.232. The highest GCF attained, the larger measurement range for GCF (which involves a larger variability of sun angle above the horizon) and the presence of the net above the table grape, were the likely reasons for the better performance of GCFpyr in this crop. Further research is required to develop more appropriate calibration equations of GCFpyr taking into account the whole range of GCF variability., Work funded by the project Consolider CSD2006 – 00067 (Ministerio de Ciencia e Innovación, Spain).

46 Pags., 3 Tabls., 10 Figs. The definitive version is available at: http://www.sciencedirect.com/science/journal/01681699, Software con manual de uso en: http://hdl.handle.net/10261/45608, This paper presents a real-time, on-farm irrigation scheduling software (RIDECO). The software was been designed for stone fruit orchards in the semiarid conditions of Spain. The characterization of stone fruit crop water requirements for the local conditions and under different irrigation strategies is presented. Meteorological data in the study area is collected daily from the SIAR public network of weather stations in an automated fashion. Subsequently, values of cumulative degree-days are computed to identify the stages of fruit growth and crop development. The software allows performing weekly irrigation schedules under standard, regulated deficit irrigation and water restriction conditions. The irrigation scheduling software stands as a valuable tool for on-farm water resources allocation planning. It can be used to forecast the irrigation water required to meet seasonal meteorological, agronomical and managerial scenarios in stone fruit orchards. RIDECO can also be used to plan deficit irrigation strategies in cases of severe water restrictions. The software can be parameterized to adjust to specific varieties and local farming conditions. A variety of graphs assist irrigation managers in their decisions., The authors sequence in this paper follows the “first-last-author-emphasis” norm. This research was funded by the Plan Nacional de I+D+i of the Government of Spain through grant RIDECO-CONSOLIDER CSD2006-00067.

39 Pag., 8 Fig., 4 Tabl. The definitive version is available at: http://www.sciencedirect.com/science/journal/15375110, The spatial variability of the wind in the Montesnegros Irrigation District (MID), in Spain, has been analysed. From a wind series (2004–2007) registered by a reference weather station, a windspeed >2 m s−1 was observed about 50% of the time. During these periods about 70% of the time it blew from the northwest (known as the Cierzo). Wind was monitored at the reference site and at 17 sites throughout the MID. Using regression a series of the local wind velocities for the irrigation seasons 2004–2007 were estimated from the reference station data. Wind exposure for 39% of the MID area was found to be similar to that of the reference site; 25% were less exposed and 36% considerably more exposed. The spatial variability of the wind was used to calculate the suitable time for irrigation (STI, %) using Ador-Sprinkler software. STI was simulated for different irrigation systems and strategies: standard – Christiansen’s uniformity coefficient (CUC) > 84% and wind drift and evaporation losses (WDEL) ≤ 20%, restrictive – CUC ≥ 90% and WDEL ≤ 15% and relaxed – CUC > 80% and WDEL ≤ 25%. At the reference site, STI varied from 50 to 56% of the total time during the irrigation season time for standard strategy, from 68 to 77% for the relaxed strategy and 8 to 30% for the restrictive strategy. Excluding the restrictive strategy, the least exposed sites averaged 14% greater STI than the most exposed sites., The sequence-determines-credit approach has been applied for the sequence of authors in this paper. This research was funded by the CICYT of the Government of Spain through grants AGL2004-06675-C03-03/AGR and AGL2007-66716-C03, by the Government of Aragón through grant PIP090/2005, and by the INIA and CITA through the PhD grants program.

The final version is available at: http://www.sciencedirect.com/science/journal/01681923, The energy partitioning or Bowen ratio β at the surface, can be expressed as a function of a climatic factor C (which depends on the climatic characteristics through the climatological resistance ri) and of a surface factor S (which depends on the surface characteristics through the surface resistance rc). This paper explains an approach for estimating S and therefore β as a function of standard meteorological variables. The empirical approach is then validated by estimating the latent (λE) and sensible (H) heat flux. The experimental data were measured over grass at two semiarid locations in the Ebro river valley, NE Spain, with typical Mediterranean climates: at Mas Bove, using a Bowen ratio-energy balance method from 1991 to 1993, and at Zaragoza, using a weighing lysimeter from 1999 to 2000. Results show that the surface factor S depends on the square root of the absolute value of ri/ra (where ra is the aerodynamic resistance), with two locally calibrated empirical parameters. This result is valid for the largest possible range of situations (β values) throughout the day. Using three different hypotheses for computing ra, results for β (following Hypothesis 1) indicate a good level of performance by the model, although with a high degree of variability. The estimated latent heat flux λEest,1 tends to slightly underestimate the measured values. Under the semiarid conditions of the region, λEPM estimates obtained with the Penman–Monteith equation produce relative errors that are greater than those obtained with the proposed model once it has been calibrated. On average, sensible heat flux tends to be overestimated with the proposed method., This work was funded by the Spanish Ministry of Science and Technology under projects ENE2004-07619/ALT and REN2001-1630/CLI and, and by the Department of Universities and Research (Generalitat de Catalunya) under project 2001SGR-00306.

The definitive version is available at: http://www.sciencedirect.com/science/journal/03783774, In the last decade irrigation districts in the Ebro Valley of Spain have started to use database applications to enhance their management operations. Such applications often put more emphasis on administrative issues than on water management issues. A new irrigation district management software called “Ador” is presented in this paper. This database application has been designed to overcome limitations identified in an analysis of the software used in the study area. Ador can be used in irrigation districts independently of the type of irrigation system (surface, sprinkler or trickle) and the type of irrigation distribution network (open channel or pressurised). It can even be used in irrigation districts combining different types of irrigation systems and different types of irrigation distribution networks. The software can be used with minimum district information. The goals are to manage detailed information about district water management and to promote better on-farm irrigation practices. Ador is currently used to enhance management of 62 irrigation districts accounting for some 173,000 hectares in the Ebro Valley., National Plan for Research and Development of the Government of Spain (AGL2000-0151-P4-02). FEDER II of the European Union (2FD97-0547-C02). I3P program of the European Union. Oficina del Regante (Government of Aragón, FEOGA funds of the European Union).

The final editorial version is available at: http://www.sciencedirect.com/science/journal/03783774, The effects of years of extreme rainfall events on maize water-use under traditional flooding irrigation in a Mediterranean landplane were estimated through a simulation assessment; combining a weather generator with an agrohydrological simulation model. Two options: “Fully Irrigation” and “Deficit Irrigation” were considered in the simulations as the extreme water-management situations. Besides, a 2-m depth shallow water table and Free Drainage were considered as the typical extreme situations that can be found at the bottom of the simulated soil layer. Thirty “Dry” (DY) and “Wet” (WY) years were randomly selected from the weather generator output. The model SWAP was used to simulate the Relative Transpiration (RT), i.e. ratio between actual and maximum maize transpiration, Actual Maize Evapotranspiration (ETC), Percolated Water and Capillary Rising during wet and dry years and for each of the irrigation and bottom condition options. According to the modelling results, average mean RT is about 80% and 90% in dry and wet years, respectively. RT and ETC variability are very high under dry conditions although such variability is notably reduced if a suitable irrigation option is considered. Capillary rising can play a very important role during dry years in those places where irrigation is not enough, but water table is relatively shallower. On the other hand, a shallower water table can carry out RT reductions during wet years, due to water excess, although these negative effects are comparatively lower than those produced by rain scarcity. Besides, percolated water during wet years is very high, particularly in well irrigated farms.

The definitive version is available at: http://www.sciencedirect.com/science/journal/00221694, This paper reports the evaluation of three geostatistical interpolation methods (ordinary kriging, cokriging and modified residual kriging) to interpolate long-term mean total annual reference evapotranspiration (AETO) and long-term mean total annual precipitation (APRE) in a mountainous region, where the stationarity hypothesis probably do not hold for the whole region, but do hold locally. AETO and APRE estimates and estimation errors were evaluated at validation stations. Estimates and computed estimation error variances (used as indicators of estimation uncertainty) were also obtained at 1913 5 km grid points. In general, estimates at validation stations were in good agreement with observed values for all interpolation methods, although modified residual kriging estimates of APRE were slightly worse than those obtained by the other two methods. Based on mean absolute error (MAE) and mean squared error (MSE) at validation stations, no method ranked clearly above other for interpolation of AETO. At grid points, AETO estimation uncertainty was improved by cokriging by about 11.5% and 8.4% compared with ordinary kriging and modified residual kriging, respectively. Likewise, cokriging was superior for interpolation of APRE in terms of MAE and MSE obtained at validation stations. At grid points, cokriging reduced estimation uncertainty by 18.7% and 24.3 % compared with ordinary kriging and modified residual kriging, respectively, whereas modified residual kriging in general did not improve ordinary kriging results. Computed estimation error variance values indicated that modified residual kriging would reduce estimation uncertainty in areas where very few weather stations are available for interpolation., This research was funded by the Ministerio de Educaci6n y Ciencia (project CICYT-514 and a grant to the author) and the Ministerio de Agricultura (INIA, project SC93-059-061), Government of Spain. I