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13 Pags.- 4 Tabls.- 9 Figs., Surface irrigation, particularly furrow irrigation, is the most common method of water application into agricultural lands. Despite all its advantages, furrow irrigation has some demerits, such as a potential large volume of runoff losses. In this research, an approach was proposed to reduce runoff losses and to improve water flow characteristics by creating micro-dams, barriers inside the irrigated furrows. To control water flow and increase infiltration into the soil, experimental micro-dams were created at distances of 10 and 20 m, with a height of 5 cm. Field experiments were conducted at the research farm of the College of Agriculture and Natural Resources, University of Tehran, Karaj, Iran in summer of 2018. Two erosive inflow rates (0.6 and 0.9 L/s) were considered. Furrow length and spacing were 100 and 0.75 m, respectively. Results indicated that micro-dams increased the advance time, leading to increased infiltration. Micro-dams also increased the recession time, due to the increase in overland water volume. Moreover, results showed that in treatments with micro-dams, runoff was reduced by up to 45.3% in comparison to the control treatment. The change in furrow cross-sectional area during the irrigation event was also reduced. Micro-dams showed a great potential to reduce irrigation runoff losses, and should be considered as a management practice aiming at water and soil conservation., This work has been supported by the Center for International Scientific Studies & Collaboration (CISSC), Ministry of Science, Research and Technology, Iran.

Pags.- 1 Tabl.- 9 Figs. Published online: 7 June 2014. The definitive version is available at: http://link.springer.com/journal/271, A variety of techniques have been proposed in the literature for sprinkler drop characterization. An optical particle tracking velocimetry (PTV) technique is proposed in this paper to determine drop velocity, diameter and angle. The technique has been applied to the drops emitted by an isolated impact sprinkler equipped with two nozzles (diameters 3.20 and 4.37 mm) operating at a pressure of 175 kPa. PTV has been previously used to determine the velocity vector of different types of particles. In this research, PTV was used to photograph sprinkler drops over a region illuminated with laser light. Photographs were taken at four horizontal distances from the sprinkler, which was located at an elevation of 1.65 m over the soil surface. Drop angle and velocity were derived from the displacement of the drop centroid in two images separated by a short time step. Centrality and dispersion parameters were obtained for each drop variable and observation point. Results derive from the analysis of 2,360 images. Only 37.5 % of them (884 images) contained drops which could be processed by the PTV algorithm, resulting in a total of 3,782 drops. A filtering algorithm just validated 1,893 valid drops, which were successfully analyzed. The proposed technique uses expensive equipment requiring continued protection against irrigation water. This methodology has proven valuable to characterize irrigation water drops. Despite its robust measurement procedure, further comparison with other techniques seems necessary before this optical technique can be recommended for practical use in sprinkler drop characterization., Thanks are due to the Centro Interamericano de Recursos del Agua from the Universidad Autónoma del Estado de México and to the Maestría en Ingeniería Aplicada Orientación Recursos Hidráulicos of Universidad Autónoma de Zacatecas. Thanks are also due to CONACYT for providing a scholarship to Cruz Octavio Robles Rovelo to pursue Master Degree studies.

44 Pags., 5 Tabls., 7 Figs. The definitive version is available at: http://www.springerlink.com/content/0342-7188/, Sprinkler kinetic energy has been linked to a number of problems in irrigated fields. This work presents the characterization of sprinkler drop kinetic energy and specific power from low-speed photographic drop data using a commercial impact sprinkler and three operating pressures. The spatial variability of specific power (W m−2) was assessed for different sprinkler spacings, showing different patterns in rectangular and triangular spacings. The specific power uniformity coefficient ranged from 38–77%, depending on sprinkler spacing and operating pressure. An attempt was made to characterize specific power from estimated (measured diameter and estimated velocity) and simulated data (using a ballistic model). While estimated data produced adequate results, simulated data resulted in a large overestimation. Discrepancies in kinetic variables between measured and simulated drop data permit to conclude that it is important to continue experimental drop characterization efforts as well as sprinkler simulation model development., This research was funded by the Agencia Española de Cooperación Internacional para el Desarrollo (AECID). Thanks are also due to the Universidad Autónoma de Zacatecas, México.

A field experiment was performed to study the effect of the space and time variability of water application on maize (Zea mays) yield when irrigated by a solid set sprinkler system. A solid set sprinkler irrigation layout, typical of the new irrigation developments in the Ebro basin of Spain, was considered. Analyses were performed (1) to study the variability of the water application depth in each irrigation event and in the seasonal irrigation and (2) to relate the spatial variability in crop yield to the variability of the applied irrigation and to the soil physical properties. The results of this research showed that a significant part of the variability in the Christiansen coefficient of uniformity (CU), and wind drift and evaporation losses were explained by the wind speed alone. Seasonal irrigation uniformity (CU of 88%) was higher than the average uniformity of the individual irrigation events (CU of 80%). The uniformity of soil water recharge was lower than the irrigation uniformity, and the relationship between both variables was statistically significant. Results indicated that grain yield variability was partly dictated by the water deficit resulting from the non-uniformity of water distribution during the crop season. The spatial variability of irrigation water depth when the wind speed was higher than 2 m s−1 was correlated with the spatial variability of grain yield, indicating that a proper selection of the wind conditions is required in order to attain high yield in sprinkler-irrigated maize.