http://yetl.yabesh.ir/yetl1/handle/yetl/19005 Tue, 28 Apr 2026 10:18:49 GMT 2026-04-28T10:18:49Z http://localhost:80/yetl1/bitstream/id/184303/ http://yetl.yabesh.ir/yetl1/handle/yetl/19005 http://yetl.yabesh.ir/yetl1/handle/yetl/4309580 Development of the Diversion Runoff Calculator to Estimate Agricultural Water Consumption and Irrigation Diversions at the Field- to Basin-Scale in Northeastern Utah Michael Follum; Betsy Morgan; Leland Dorchester; Adolph “Shane” Coors; Anthony Powell; Bart Leeflang; Mark Wahl; Joshua Rayes With the western United States experiencing aridification and prolonged drought, there is a need for improved water management to understand irrigation water requirements and to forecast how drought mitigation efforts may affect irrigation operations at the field-, canal-, and basin-scale. This paper presents the Diversion Runoff Calculator (DRC), which uses geospatial and field-scale data sets (monthly evapotranspiration estimates from OpenET and effective precipitation estimates from the ET Demands model) to estimate irrigation requirements, field runoff, and canal seepage at the field-, canal-, and basin-scale. Because the geospatial data sets characterize field-scale attributes (irrigation method, canal lining, etc.), changes to these attributes can be made to reflect potential drought mitigation strategies and processed using the DRC. The effects of drought mitigation strategies are realized through changes in irrigation demands. The DRC is tested on irrigated lands along the Duchesne River in northeast Utah. At the field scale, the study finds that the consumptive use values calculated using OpenET data and the ET Demands model match well with the irrigation requirement tables typically used by water managers. The field-scale consumptive use data are aggregated to the canal-scale and a transit loss within the canal is calculated, resulting in an estimated diversion flow requirement at the headgate of each canal, which is subsequently aggregated to the basin scale. The canal- and basin-scale diversion estimates reasonably replicate observed diverted flows, with basin-scale Nash–Sutcliffe Efficiency of 0.74. Two test cases are presented that demonstrate how the DRC can be used to evaluate drought mitigation strategies. The first considers lining all the earthen canals, which results in a 5.0% reduction in diverted flows. The second considers converting all flood-irrigated fields to sprinkler-irrigated fields, which results in a 4.4% reduction in diverted flows. Although the geospatial data sets used are Utah-specific, avenues for applying the DRC in other western states are discussed. Wed, 01 Jan 2025 00:00:00 GMT http://yetl.yabesh.ir/yetl1/handle/yetl/4309580 2025-01-01T00:00:00Z http://yetl.yabesh.ir/yetl1/handle/yetl/4309579 Velocity Distributions in Open Channels and the Calculation of Discharge John D. Fenton The accurate representation and integration of velocity measurements in open channels is important in irrigation and river engineering. The traditional approach for velocity is to use an approximate physical theory, giving the well-known logarithmic formulas, plus less well-known correction formulas in terms of mathematical functions. The approach is criticized here as being too prescriptive and not capable of systematic improvement or generalization. A different paradigm is suggested, oriented toward practice and numerical solution. The velocity is written as a polynomial, a series of monomial terms, in terms of the relative height of a point above the bed. In the first contribution it is raised to a fractional power, mimicking the actual shear flow in a stream where velocity goes to zero on the bed but with a large gradient. Polynomials with just two extra terms can describe well a number of laboratory and field measurements. It is computationally better, however, to use the monomials rearranged as Chebyshev polynomials. This is simply done and can be used as a means of approximating several measurements at arbitrary points to give an accurate depth-averaged velocity. Using the polynomial approximation, the accuracy of standard hydrographic and hydrometric methods is then examined. The well-known two-point 0.2/0.8 method of integration is surprisingly proved to be accurate to within 1% for any smoothly varying quantity. Such high accuracy has been found experimentally; what is noteworthy is its general theoretical validity—and its simplicity. Procedures for integrating across a stream are then considered and it is shown that a common approach, the mean section method, is not correct. Then the polynomial approximation method is generalized to two dimensions to give a method for the calculation of discharge also for arbitrary distributions of velocity measurement points in general cross sections. The velocity distribution in an open channel can be simply and accurately approximated by a polynomial in terms of the local height above the bed expressed as a fraction of the total depth. The first polynomial term is a simple fractional power of that quantity, which mimics the well-known behavior that as the velocity goes to zero on the bed, the gradient becomes large. It is computationally better for other polynomial terms, instead of just integer powers, to use combinations of them in the form of special functions, for which formulas are given. Then, if several velocity measurements are made on a vertical line, they can be approximated using optimization methods. To calculate discharge accurately, such a procedure is actually not necessary. A surprising and general proof is given that any smoothly varying physical quantity can be integrated to within 1% accuracy using just the mean of values at 20% and 80% of the domain. This has been determined empirically in hydrography and hydrometry and is standard practice. The simplicity and accuracy of the procedure is most fortunate. Finally, the polynomial method is extended to two dimensions, enabling the approximation of arbitrary measurements of the velocity field and the determination of discharge in any river or canal. Wed, 01 Jan 2025 00:00:00 GMT http://yetl.yabesh.ir/yetl1/handle/yetl/4309579 2025-01-01T00:00:00Z http://yetl.yabesh.ir/yetl1/handle/yetl/4309578 Performance Analysis of the Doho Rice Irrigation Scheme in Uganda Joshua Enyetu; Larmbert Ebitu; Helen Avery The study analyzed the performance of Doho Rice Irrigation Scheme (DRIS), the largest public irrigation scheme in Uganda, using (1) water supply indicators comprising relative water supply (RWS), relative irrigation supply (RIS), and water delivery capacity (WDC) related to water supply from the system in relation to scheme crop water demand for the 2018–2019 growing season; and (2) water balance ratios of conveyance, distribution, application, and storage related to water utilization efficiency during the same period. Primary field data were collected in 2021 through measurements of canal water flows at different system levels, and measurement of field level soil properties and moisture contents. Climate data from Uganda National Meteorological Authority, Tororo station, were analyzed using commercially available software to compute the crop water and irrigation requirements of paddy rice. From the analyses of the water supply indicators, the result of the ratios of RWS, RIS, and WDC were, respectively, 2.82, 9.04, and 2.28, whereas conveyance, distribution, field application, and storage efficiencies were, respectively, 80.7%, 78.4%, 71.6%, and 87.5%, with an overall scheme efficiency of 57.8%. RWS and RIS values higher than one mean DRIS has plenteous water supply, sufficient to meet crop water demand. In particular, a RWS value of 2.82 shows adequate supply relative to demand. The RIS value of 9.04, significantly higher than the ideal value of one, suggests notable inefficiencies in water usage within the DRIS. Also, the WDC value of 2.28 shows that the canal capacity was not a limiting factor to meeting the peak consumptive requirement. Despite this plenteous supply, analysis of efficiency shows that the water was not particularly efficiently distributed nor efficiently applied, even though the storage efficiency was high. Methodological lessons from the study emphasize more data collection intensity and more adequate data treatment to gain more comprehensive insights into irrigation system performance. Wed, 01 Jan 2025 00:00:00 GMT http://yetl.yabesh.ir/yetl1/handle/yetl/4309578 2025-01-01T00:00:00Z http://yetl.yabesh.ir/yetl1/handle/yetl/4309576 Scour Characteristics Downstream of a Gabion Weir Ali Shariq; Ajmal Hussain; Zulfequar Ahmad Rectangular broad-crested gabions are economical- and environmental-friendly structures that are constructed to manage the transport of sediment in steep slope rivers. This study aims to study the pattern and extent of scour downstream of a gabion weir and impermeable weir to solve the existing problem of excessive scour by impermeable structures. Laboratory experiments were conducted for scouring at downstream of the gabion weirs and impermeable weirs under free flow conditions. The experimental setup consists of a rectangular channel with dimensions of 9.6 m in length, 0.5 m in width, and 0.6 m in height. The data range for the present study includes a densimetric Froude number from 0.72 to 1.47, a ratio of downstream depth to crest height of the weir from 0.44 to 0.94, and a porosity ranging from 0.37 to 0.395. The collected data were analyzed to propose relationships for the gabion weir’s maximum scour depth, length, dune height, and nondimensional scour profile. The maximum scour depth was observed as a function of porosity, densimetric Froude number, and the downstream water depth ratio to the gabion weir crest height. The range of validation of the proposed relationship for scour depth shows an error within the range of ±20%. Sensitivity analysis shows that porosity is the most significant input parameter for scour depth. Wed, 01 Jan 2025 00:00:00 GMT http://yetl.yabesh.ir/yetl1/handle/yetl/4309576 2025-01-01T00:00:00Z