Journal of Irrigation and Drainage Engineering

Sports fields are highly functional places for economic and social purposes nowadays. Effects of various climate conditions on sports fields are very crucial in terms of playability, the health of the players, and the pleasure of spectators. This study aims to evaluate drainage behaviors of different sports field drainage techniques considering hydrological aspects. For this purpose, 40 experiments were carried out. In the experiments, a rainfall simulator (RS) was used to create different storms that included four different design hyetographs with various rainfall intensities and six different constant rainfall intensities. The pipe drain (PD), suspended water table (SWT), sand groove (SG), and slit drain (SD) were also investigated as drainage techniques that are the most commonly known and suggested in the literature. Drain outflows were obtained and drawn with respect to the experiment time for each storm and constant rainfall condition. S hydrographs were consecutively created for the increasing value of the constant rainfall intensities. The hydrograph parameters that are the time to start to drain, maximum outflow, time to reach maximum outflow, and infiltration rate were also evaluated for PD, SWT, SG, and SD. It is clearly stated that the maximum drainage outflow of the SD was greater. The hyetographs had more distinctive effects on the shape of the drainage outflow hydrographs for the PD and SWT. The rainfall intensities were not separately the cause of surface ponding for each drainage method in this study. For $90{\mathrm{mmh}}^{-1}$ and lower rainfall intensities, three drainage methods demonstrated similar drainage behaviors except for SD. The subsequent greater rainfall intensities induced different maximum drain outflows for each drainage technique. Furthermore, the SD had the maximum average outflows in every constant rainfall intensity. As a result, under the specific conditions, which are a nonweary surface, high level sanded rootzone, and good construction, the suggested four drainage systems demonstrated similar hydrologic behaviors even if some hydrograph parameters were slightly different.

Timely monitoring and regulation of the transport and distribution of soil water and heat are appropriate methods to ensure and improve crop yields. With the degradation of the oxo-biodegradable film, the upper boundary condition is a time-variable boundary, and soil water-heat transport is more complicated, comparing with conventional plastic film. Based on HYDRUS-2D version 2.02 and the characteristics of mulching films, a soil water-heat coupled transport mathematical model of drip irrigation was established, and the simulated soil water content and temperature were tested against three-year field observations for calibration and validation purposes. The model prediction demonstrated that the induction periods of oxo-biodegradable film mulching differed in different hydrological years. In normal flow years, an induction period of 50–80 days had higher water use efficiency. While the window would increase to 50–100 days in low flow years. As for temperature, comparing with conventional plastic film mulching, the decreasing trend of temperature started to slow down when the induction period increased to 70 days. Therefore, the optimal induction period of the oxo-biodegradable film is 50–70 days.

High-fidelity models can simulate many detailed hydrodynamic features of flow in natural rivers. However, it is challenging to explicitly capture the effects of highly complex bathymetry and bank line vegetation on the simulation results of models. Often detailed hydrographic data representing the channel bed is unavailable, requiring the use of more simplified representations of the channel bathymetry. Furthermore, explicit modeling of vegetation is generally not accounted for in most three-dimensional (3D) numerical models, which could lead to significant error in obtaining accurate results. In this study, we have investigated these issues by comparing the effect of (1) different sonar survey resolutions of the channel bed, and (2) trees on the large-eddy simulation (LES) results of a test case in a reach of the American River, California. This comparison has shown that the higher resolution survey reduced the near bed velocities and bed shear stresses and increased the number of vortical structures in areas with highly detailed surface structures. The hydrodynamic results from the tree-resolving LES were compared against a baseline LES case that excluded trees. The results indicate that the inclusion of trees in the simulations can significantly alter the flow dynamics of the river by decreasing the flow momentum and bed shear stress along the banks, while increasing the momentum and stresses in the middle of the river. While trees appear to increase turbulent fluctuations near the bank, these fluctuations probably do not contribute to erosion processes. These findings have the potential to improve the accuracy of high-fidelity modeling of natural streams and rivers and add to the general understanding of the flow dynamics in natural waterways.

Transported debris in open channels can lead to accumulations and, therefore, cause blockages at trash racks. Velocity distributions and flow patterns change because of these blockages and may lead to geomorphic condition evolution around the blocked racks. Despite numerous investigations related to racks, systematic studies of velocity distributions around rack accumulations of debris blockage are missing. The debris accumulations were simulated using a horizontal plate blockage. The experiments were performed for different blockage ratios ($B_r=0.13$, 0.25, 0.32, 0.45, 0.50, 0.64, and 0.69) and various approach Froude numbers (${\mathsf{F}}_o=0.06$, 0.07, 0.08, 0.10, and 0.12) to analyze the up- and downstream velocity fields in the middle and near the wall in the flow direction around the rack. Overall, the results show that the velocity distributions were influenced by the blockage and new velocity results are provided for both up- and downstream of the rack. Additionally, a new average velocity equation is proposed for a rack with attached plate of large wood that considers the effects of blockage ratios and Froude numbers.

Location of maximum scour depth is a key feature for the accurate design of scour countermeasures. Experimental results show that the maximum scour depth around wide setback abutments migrates to a location further downstream than that observed conventionally at the tip for narrower abutment. The wide abutment caused two scour holes to form, with a larger primary scour hole and a smaller secondary scour hole downstream from the first, and this has important implications for scour protection at the structure’s foundation. For this study, 55 experiments were conducted with seven abutment aspect ratios and the migration of the maximum scour locations were measured. The results reveal that $R_x$ (the normal distance from abutment face to the location of maximum scour depth) is affected by the flow intensity, flow depth, and abutment aspect ratio. The value of $R_x$ is larger as flow intensity decreases for the same abutment aspect ratio. However, $R_y$ (the distance from the centerline of abutment face to the location of maximum scour depth parallel to flow direction) is only affected by flow depth and abutment aspect ratio. Empirical equations are proposed to predict the locations of the maximum scour depth for wide abutments in compound channels.

The current equations for curb inlet opening sizing often inaccurately estimate the capture efficiency of small urban green stormwater infrastructure (GSI) curb inlets. Most of these equations are based on studies with openings much larger than typical urban GSI curb inlets (i.e., less than 0.6 m). This study introduces a new, three-dimensional (3D) numerical approach for evaluating curb efficiency using the ANSYS Fluent computational fluid dynamics (CFD) model that can be applied to a wide range of curb inlet conditions. Simulated curb efficiency results for typical urban curb inlet openings are verified by laboratory experiments of field-scale conditions. A high prediction accuracy is obtained (Nash-Sutcliffe efficiency $\mathrm{coefficient}=0.97$) between the observed and the CFD model results. The CFD model also performs better than three commonly used methods for estimating curb inlet efficiency; the Hydraulic Engineering Circular No. 22, and the 2009 and 2012 Comport and Thornton equations. The high level of accuracy observed in this study makes 3D CFD modeling a more effective alternative to existing equations for evaluating GSI curb inlet efficiency. The quick simulation times realized in this study also demonstrate that CFD modeling of GSI inlets has an added benefit of quickly evaluating several design alternatives without a need for costly full-scale or on-site testing often performed to assess such inlets.

The extensive irrigation systems of South Asia are predominately a hierarchy of canals delivering water to a tertiary unit. A network of field channels transfers water within the tertiary unit to the field where it is applied using surface irrigation. The network of field channels within a tertiary unit is often left to the farmers/farmer associations to construct, maintain, and operate. This paper develops a mathematical model/algorithm for routing the field channel along the existing field boundaries such that every field is serviced by a field channel and minimizing the total length of the field channel as a proxy measure of the cost of construction of field channels. The models developed in this paper are formulated as integer programs, implemented in a general-purpose solver. The model is applied to a tertiary unit of the Gomal Zam Irrigation System in Pakistan and shows that for this particular application, the optimized total length of field channels is 9,463 m compared with 11,313 m when an expert judgment is used, a reduction of 1,850 m (20%).

Better understanding of the hydraulic performance of stormwater inlets which serve as the linkage between the surface drainage system and the underground sewer system is important to avoid urban flooding. Continuous transverse grates were not well studied in the literature, and, therefore, eight types of such grates commonly used in China were examined experimentally in this study. A full-scale physical model simulating a 12-m-long and 3-m-wide road was constructed for 320 hydraulic tests with different approaching flow rates and road longitudinal slopes. Hydraulic efficiencies of the grates under different conditions were calculated, and their influencing factors were analyzed, including the Froude number and the grate’s geometry (grate length, effective length, effective width, effective length ratio, effective width ratio, opening style, and opening rate). Empirical equations are presented to relate the hydraulic efficiency and influencing factors. This research is useful for understanding continuous transverse grates and improving the engineering design of the grates.

Fifth-degree parametric equations were developed to calculate the cross-sectional dimensions and bed centerline elevations (thus, the geometric surface coordinates) between the two ends of a warped transition in a water-supply canal. A parametric modeling approach provided a smooth representation of the mixed geometry that results from the terminal sections having vastly different shapes. A generalized cross section defined by four parameters enabled a straightforward representation of various forms ranging from trapezoids to semicircles. This approach significantly simplifies the interpolation of surface coordinates between the terminal points of a transition structure. It also maintains a degree of smoothness that helps avoid undesirable consequences of channel contractions and expansions. An example is presented that applies the parametric modeling approach to designing a significant canal transition in which the cross section changes from a standard trapezoidal shape with rounded bottom vertices to a rectangular section in a steeper aqueduct that carries the flow across a broad valley.