Hydrograph shape and border irrigation efficiency

Because of the linear nature of water conveyance projects, they include various geological formations and are usually in contact with water. For these reasons, most constructed irrigation and drainage networks are subject to deformation and displacement due to problematic soils. One of these problematic beds is unsaturated expansive soil. Unreinforced trapezoidal canals are damaged when constructed on these types of soils. In the present study, this phenomenon has been studied using field observations and numerical modelling. In practice, a filter layer is used to reduce soil swelling effects on the canal lining in the Tabriz plain project. To investigate the performance of this layer, the amount of soil swelling and relative displacement of the canal section panels are measured by recording of surveying points. This phenomenon is also modelled numerically. Using the results obtained, the swelling of the bed soil is calculated at different parts of the canal section with the filter and without it and the locations of maximum movements are determined. In order to predict the interaction behaviour between unsaturated expansive soil and concrete lining under different moisture conditions, a special constitutive unsaturated soil behaviour model has been selected in the software. The results of analysis show the location of maximum deformation and stress concentration on the canal section. Using these results, the effect of joint locations to reduce the destructive interaction force can be obtained. In addition, comparison between the results of numerical modelling and field data illustrates acceptable accuracy of the numerical modelling.

Irrigation Science, 1997

An open-end graded border design procedure is presented. The proposed method based on the principle of mass conservation requires Kostiakov and Manning formulations for infiltration and roughness, respectively. The key assumption of the present design procedure is that the minimum infiltrated depth occurs at the lower border end and is equal to the required depth of infiltration. The philosophy behind the proposed design procedure is to select the appropriate flow rate q 0 and cutoff time T cof for given field conditions including the field geometry (field length and slope) and the soil characteristics (including the surface roughness coefficient and infiltration parameters). The results of two example border fields were in close agreement with those obtained from a zero-inertia model.

Applied Engineering in Agriculture, 1998

T he differences in infiltration opportunity time along a surface irrigation field cause nonuniform water distribution. Consequently, assuming that the required depth is equivalent to the soil moisture deficit, three typical irrigation results are possible depending on whether the required depth is met, undermet, or overmet along the field. Figure 1 depicts these three cases or options. Which option is unique and preferable would be a difficult task to quantify. Because of the large differences in economic, physical, social, and operation conditions that occur relative to surface irrigation, it is impossible to place quantitative judgments on any of these three cases (Walker and Skogerboe, 1987). High cost and low availability of water would certain that to overirrigate the entire field is not economical. The full irrigation, particularly with high uniformity and efficiency, and the underirrigation would be proper options. Designing surface irrigation systems with either full or over-irrigation option is far less difficult to perform than with underirrigation option. Therefore, accountable methods are available for the design of border irrigation systems with full, consequently with over, irrigation case. The methods of Soil Conservation Service (National Engineering Handbook, 1974) and Walker and Skogerboe (1987) are probably the most known and widely used border design procedures. The Soil Conservation Service method (SCSM) developed for border design lacks some hydraulic considerations. The most critical assumption associated with SCSM is that the advance and recession are parallel so that the opportunity time of infiltration is identical along the border run which is practically, even theoretically, impossible. Since SCSM was based on large field data, its use would be limited to similar conditions.

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2011

Page 1. CDRI - Cambodia's leading independent development policy research institute University of Sydney CHEM Phalla, Philip HIRSCH and SOMETH Paradis Working Paper Series No. 59 September 2011 A CDRI Publication HYDROLOGICAL ANALYSIS IN ...

En esta edición, al igual que en las anteriores, dedico esta obra, como un homenaje, a la sagrada memoria de mi padre, el Sr. Dr. Zacarías Esponda Moguel, quien con su ejemplo y profesionalismo me enseñó a querer devotamente a la profesión odontológica. El Dr. Zacarías Esponda M. nació en Chiapas el año de 1875 y se graduó como Doctor en Cirugía Dental (DDS) en el año de 1899 en la Universidad de Pensilvania, Filadelfia Pa. EUA. Fue el primer profesor de Prótesis Estética que utilizó porcelana, en la Escuela Nacional de Odontología, UNAM, de 1926 a 1933.