Search results for "IRRIGATION"
showing 10 items of 342 documents
Modeling of Water Distribution under Center Pivot Irrigation Technique
2021
AbstractAiming to quantify the impacts of the center pivot irrigation technique on soil moisture dynamics and to improve irrigation crop water needs, a mathematical model was developed to estimate ...
Determining Optimal Seasonal Irrigation Depth Based on Field Irrigation Uniformity and Economic Evaluations: Application for Onion Crop
2016
The crop water production function (WPF), representing the relationship between crop yield and seasonal irrigation water, is a useful tool for irrigation planning purposes. The objective of the paper is to propose a methodology to evaluate the optimal seasonal irrigation depth based on the crop production function, the field distribution uniformity, and economic considerations. An extended unpublished database experimentally obtained on the onion crop on the island of Kula, Hawaii, was initially used to assess the crop WPF. The combination between the crop WPF and the model representing the field distribution uniformity allowed determining the area subjected to underirrigation and overirrig…
Assessing Stage-Discharge Relationships for Circular Overflow Structure
2018
Circular overflow structures are used in irrigation and drainage networks as water measuring structures. Different approaches can be found in the literature to formulate the stage-discharge relationship of the circular weir. They are mainly categorized in three groups: (1)methods trying to simplify the complex elliptic integrals coming from the theoretical discharge equation; (2)methods that use the orifice formula and a discharge coefficient specific for the circular weir; and (3)approaches using dimensional analysis and Buckingham's Theorem. In this study, a nondimensional stage-discharge formula was obtained using Buckingham's Theorem to define the flow over the sharp-crested circular we…
Comparison of SWAP and FAO Agro-Hydrological Models to Schedule Irrigation of Wine Grapes
2012
This paper compares two agro-hydrological models that are used to schedule irrigation of a typical Mediterranean crop. In particular, a comparison between the Food and Agriculture Organization (FAO) model, which uses a black box approach, and the soil-water-atmosphere-plant (SWAP) model, which is based on the numerical analysis of Richards' equation, are shown for wine grape. The comparison was carried out for the 2005 and 2006 irrigation seasons and focused on hydrological balance components and on soil water contents. Next, the ordinary scheduling parameters were identified so that the performance of the two models, which aimed to evaluate the seasonal water requirements and the irrigatio…
On Saline Irrigation Problems in Sicily Remarks to Professor Cavazza’s Report
1968
I should like to clarify that part of Professor Cavazza’s report which deals with the activities of the Agronomy Institute in the University of Palermo. This Institute, under my direction, has interested itself — among other subjects — in the utilization, for irrigation purposes, of the waters of the River Salso which crosses Sicily from North to South. The water from this river becomes saline because of the hydric contribution of affluents originating from zones which belong, from the geological point of view, to gypsum-sulphuric formations also rich in rock-salt deposits.
Soil structure and bypass flwo processes in a Vertsol under sprinkler and drip irrigation.
2007
In this paper morphological and physical characteristics, as well as flow behaviour of a Mediterranean Vertisol under the influence of two different irrigation systems currently used for irrigation, i.e. drip and sprinkler systems, were compared. No differences in soil texture, compaction and in potential cracking were found on cores from the two fields. However, field application of methylene blue showed the presence of continuous macropores, penetrating up to depths of 20-25 cm from the soil surface, in the field where the drip system was in use (field 1). This was considered to be the pre-existing soil structure. Instead, macropores terminating at a depth ranging between 5 and 10 cm from…
On the relationship between some production parameters and a vegetation index in viticulture
2013
The use and timing of many agronomical practices such as the scheduling of irrigation and harvesting are dependent on accurate vineyard sampling of qualitative and productive parameters. Crop forecasting also depends on the representativeness of vineyard samples during the whole phenological period. This manuscript summarizes the last two years of precision viticulture in Sicily (Italy); agronomic campaigns were carried out in 2012 and 2013 within the "Tenute Rapitalà" and "Donnafugata" farms. Normalized Difference Vegetation Index derived from satellite images (RapidEye) acquired at berry set, pre-veraison and ripening phenological stages (occurred at June, July and August respectively) ha…
Estimating Maize (Zea mays) cvapotranspiration from NOAA-AVHRR thermal data in the Albacete area, Spain
1994
Abstract We have estimated evapotranspiration from maize (Zca mays) using NOAA thermal images infrared and meteorological data, by means of the relation where Ed is the daily evapotranspiration, is the daily net radiation expressed in mm of water per day, (Ta−Ts)i is the temperature difference between air and corn surface obtained near midday, and Bi is a semi-empirical constant which has been calculated as 0·53±0·10mm day−1K−1. We have tested the method obtaining actual daily evapotranspiration of maize with an acceptable precision (±0·9 mm day−1 taken Penman's method as the standard). Finally, a practical example is included, in which the different steps followed for applying the develope…
Assessing actual evapotranspiration via surface energy balance aiming to optimize water and energy consumption in large scale pressurized irrigation …
2017
Satellite imagery provides a dependable basis for computational models that aimed to determine actual evapotranspiration (ET) by surface energy balance. Satellite-based models enables quantifying ET over large areas for a wide range of applications, such as monitoring water distribution, managing irrigation and assessing irrigation systems’ performance. With the aim to evaluate the energy and water consumption of a large scale on-turn pressurized irrigation system in the district of Aguas Nuevas, Albacete, Spain, the satellite-based image-processing model SEBAL was used for calculating actual ET. The model has been applied to quantify instantaneous, daily, and seasonal actual ET over high- …
Bypass flow, salinization and sodication in a cracking clay soil
2004
Abstract In Sicily, the increasing scarcity of good-quality waters is spreading irrigation with saline–sodic waters, thus enhancing the risk of soil secondary salinization and sodication. Sustainable management strategies are urgently needed in Sicily to prevent extent of salinization and sodication, thus preserving soil quality. Since irrigation is performed in cracking soils using irrigation systems involving high application rates, bypass flow of water and solutes occurs during irrigation. The objectives of this paper were (i) to investigate the process of Na–Ca exchange and subsequent salinization/sodication during bypass flow and (ii) to explore possibilities of using cyclic strategies…