As we wrote in the summary of this special issue, the purpose of this Special Issue is to report, in more detail, research of water resources management in the frame of sustainable development ...
ABSTRACT
The effects of the North Atlantic Oscillation (NAO) on a second order‐mixed exponential stochastic model (MC2ME) of daily precipitation were detected for 33 weather stations located in ...southern Spain. The stations exhibit a wide range of elevations and distance from the Atlantic Ocean and consequently have large variations of mean annual precipitation and mean annual number of wet days. Annually, periodic parameters were obtained by numerical maximum likelihood fitting of Fourier series utilizing 54 years of concurrent data for each station. NAO effects were determined by perturbing these parameters by functions of the NAO Index. The Akaike information criterion (AIC) was used to select the appropriate number of Fourier harmonics for each parameter and to determine if the non‐stationary model with perturbed parameters was superior to the annually periodic model. Likelihood ratio tests showed that improvements in log likelihood functions by NAO perturbations of the logits of transition probabilities and the periodic function of the mean of the mixed exponential were highly significant. Improvements in the log likelihood functions were obtained by perturbing only during the winter months. Limited goodness of fit analyses by simulations showed that the NAO perturbations led to increased variance of annual precipitation and greater ranges of annual maximum and minimum precipitation as compared to simulations with annually periodic parameters.
The development of the wet bulb under drip irrigation in sand-covered soils presents a different behavior compared to the one observed in homogeneous soils. Moreover, the presence of a very active ...crop imposes a series of variations that have not been fully characterized. The aim of this work is to present the data acquisition methodology to calibrate and validate the Hydrus-3D model in order to safely define the evolution of moisture in wet bulbs generated in stratified “sanded” soils characteristic of greenhouses with intensive pepper crop under drip irrigation. The procedure for collecting and processing moisture data in stratified soils has been defined. Soil permeability; retention curve, texture, and bulk density have been measured experimentally for each material. It has been found that the inclusion of a previous day in the simulation improves model predictions of soil moisture distribution. In soils with less gravel, a lower average stress and a more homogeneous moisture distribution were observed. It has been proved that the Hydrus-3D model can reproduce the behavior of sand covered soils under intensive greenhouse growing conditions, and it has been possible to verify that the predictions are adequate to what has been observed in the field. In view of the results, the Hydrus-3D model could be used to establish future irrigation strategies or to locate the optimal placement point of tensiometers that control irrigation in sandy soils for intensive agriculture.
The high productivity and efficiency of the use of irrigation water that characterizes greenhouse horticultural crops can be affected by poor irrigation distribution uniformity. The objective of this ...work was to estimate the average irrigation distribution uniformity (DU) of the greenhouses in Almería, determining the influence of the irrigation water quality as well as the production system on this uniformity. A prospective study was carried out in which commercial farms were selected that used different water qualities (groundwater vs. reclaimed) with different production systems (organic vs. conventional/integrated). The average irrigation distribution uniformity in the greenhouses of Almería was 80%. The farms with organic production systems presented a drastic DU reduction with respect to conventional farms (48% vs. 88%). The DU of the irrigation water presented in commercial farms irrigated with reclaimed water presented a lower DU than those irrigated with groundwater (76% vs. 86%). The distribution of irrigation depth of water in the greenhouses showed slight variations (from 3.2 to 2.9 mm) depending on the emitter position, with the highest values being at the head of the sub-main pipe and dripper line and the lowest at the end of the sub-main pipe and dripper line. The depth of water values was very close to the theoretical average of 3 mm. Water quality affects the distribution pattern of the depth of water in greenhouses. Installations irrigated with reclaimed water showed greater oscillation of the water depth within the sub-unit, varying from 3.6 to 2.0 mm, although the average depth was located close to the theoretical depth (3 mm). The production system affected the distribution of the depth of water—in the organic system, the depth underwent greater variation depending on the position of the emitter in the sub-unit, ranging from 1.7 to 3.3 mm. In addition, within this production system, the median depth of water was close to 2.5 mm, lower than the theoretical depth (3 mm), which denoted a certain generalized filling that was accentuated at the end of the dripper line and sub-main pipe.
El arroz es regado por inundación manteniendo una altura de agua constante y alcanzando unos requerimientos de agua elevados. A la salida de la parcela hay un canal de desagüe cuyo control permitirá ...establecer prácticas para reducir el gran consumo de agua. Se ha diseñado un aforador de estrechamiento largo para cubrir el intervalo completo de caudales a aforar. Puesto que el canal de desagüe tiene una sección trapecial, la garganta del aforador será también trapecial para disminuir las pérdidas de carga. Un nuevo procedimiento se ha desarrollado en una hoja de cálculo Excel que permite diseñar directamente las dimensiones de la sección estrechada, talud de las paredes y anchura de la base, eligiendo previamente el límite modular, la altura del umbral y la longitud del estrechamiento más en concordancia con las características del canal. Los resultados demuestran la precisión y viabilidad del procedimiento.
La escasez de agua y la creciente demanda de alimentos imponen la utilización de tecnologías más eficientes en el regadío. Por tal motivo, se abordaron los fundamentos hídricos e hidráulicos del ...riego subsuperficial a demanda mediante vasos comunicantes (RSVC), estudio de caso cultivo de col rizada. El sistema estuvo compuesto por un depósito de agua, una cubeta con carga hidráulica constante, una línea de derivación, laterales de riego, emisores y vasos de cultivo. La pérdida de carga en el sistema, para el lateral más alejado, fue 7.38491 mm.c.a., permitiendo operar a presiones muy bajas sin requerimiento energético. Debido a la continuidad hidráulica, generada por la tasa evapotranspirativa, los cultivos no sufrieron estrés hídrico, obteniéndose un rendimiento promedio de 360 g de materia fresca/planta, con una eficiencia de uso del agua de 22.38 g/l, rendimientos favorables cuando se compara con otros estudios.
•An experimental study increasing the area of cultivation of the hydraulic structures called suka kollus is presented.•Suka kollus are one of the most important hydraulic structures based on ...ancestral technology developed in the Andean region.•Management options have been considered which allow farmers to keep the benefits associated with this production system.•The best results were achieved in mixed drainage systems with one or two intermediate drains.
The suka kollus, considered among the most important hydraulic structures of ancestral Andean technology, are used as a technique for crop production in flood-prone soils, enabling subsurface irrigation of crops by means of drainage channels. They also generate a thermoregulatory effect depending on the channel/ridge ratio and the total size of the infrastructure. They could be a valuable way of making use of marginal soils if some of the drainage channels are replaced by underground drains to increase the area of cultivation. This work was therefore undertaken to study the flow of water under a “mixed” drainage system (surface and subsurface drainage) adapted to the suka kollus system.
The work was carried out in marginals in the Kallutaca area, La Paz, Bolivia. The potato cultivar ‘Imilla negra’ (Solanum tuberosum ssp. andigena) was used in four treatments with different platform widths: T1 (control), the traditional system in which all drainage was via open channels; and T2, T3 and T4, where one, two and three channels were, respectively, replaced by drains. The study describes the comparison between T1 treatment, with open drains at a depth of 1 m and platform width of 6.5 m (T1) with the other treatments, i.e. subsurface pipe drains at a depth of 1.2 m and a platform widths of respectively 12 m (T2, where one channel was replaced by a drain), 18 m (T3, where two channels were replaced by drains) and 25 m (T4, where three channels were replaced by drains)
The results showed that the distance of 6.5 m between drainage channels, commonly used in traditional suka kollus, was less than the calculated distances. As such, it was possible to expand the area of the platforms by setting the drainage channels between 10 and 14 m apart. Crops yield in the T2 and T3 treatments (10.67–11.35 Mg/ha, respectively) are significantly higher compared to the traditional open drainage system, T1 (8.33 Mg/ha) and the wider platform width of 25 m, T4 (7.3 Mg/ha) due to the higher height of plants and the greater number of tubers per plant, compared to the control. Likewise, the high clay percentage of the second stratum of the T3 treatment could be beneficial in terms of greater retention of water at the root level, mainly for periods of water deficit. The crop water requirements were covered by the upward flows from the water table and by precipitation, demonstrating that the suka kollus system is sustainable under current climatic conditions.
► Indicators according to crop type, irrigation method, soil texture, and plot size. ► The influence that each individual factor permits to improve irrigation performance. ► Irrigation is deficient ...given that the value of the RIS indicator is relatively low. ► RWS indicator achieves higher values indicating that evaporation demand can be met.
This paper examines irrigation water management in the Genil-Cabra Irrigation District of the Province of Cordoba (southern Spain) using three irrigation indicators: relative irrigation supply (RIS), relative water supply (RWS), and relative rainfall supply (RRS). The three indicators are calculated both globally and by grouping the data according to crop type, irrigation method, soil texture, and plot size. Then, it is possible to determine the influence that each individual factor has on irrigation management and take subsequent measures to improve irrigation performance. All of the information regarding agronomic and hydraulic variables has been included in a geographical information system (GIS) to facilitate data management.
The results show that irrigation is deficit given that the mean value of the RIS indicator is relatively low, around 0.60. However, the RWS indicator achieves higher mean values, normally above 0.80, indicating that evaporation demand can be met throughout the crop development cycle. The RRS indicator shows less variability with mean values around 0.40. This indicator, together with the RWS indicator permits the evapotranspiration fraction covered by rainfall to be determined.
The mean values of the calculated indicators are very useful for gaining a better understanding of irrigator behavior and general irrigation trends, although the study sample is still insufficient to characterize a large irrigation area as a whole.
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