Journal of Irrigation and Drainage Engineering

The effect of varying vortex settling basin (VSB) outlet configurations on the removal of sediment particles $>75\mathrm{\mu m}$ was computationally investigated using ANSYS Fluent’s Euler-Lagrange approach, which incorporated supervised optimization and was validated by physical modeling. A rectangular centroidal outlet was established with a low outlet weir and a shaft with the following dimensions: length equal to it 1.28* Inlet diameter, breadth equal to inlet diameter, and height equal to inlet diameter located 180° opposite the inlet. The shaft was designed for partially full conditions. A low weir height with less than the submergence depth is recommended at small river abstraction works ($<100\mathrm{L}·{\mathrm{s}}^{-1}$).

Grate and curb-opening inlets are part of pavement drainage structure function to discharge excess stormwater runoff on the street. One of the main challenges of these inlets is to effectively discharge the runoff, part of which if not properly controlled would lead to surface ponding on the street and eventually floods. Flood occurrences are mostly governed by hydrological and hydraulics parameters that are highly associated with uncertainties. Uncertainties are expected to contribute from the spreads of water moving on the street, which define the head computation over the inlets. Thus, this paper aims at carrying out a reliability assessment of several types of grate and curb-opening inlets using data obtained from a full-scale half roadway model built in the laboratory. Measurement of parameters was translated into random variables to be incorporated into three newly developed limit state function models. The Monte Carlo simulation method was used to simulate the models and the final outcomes were in the form of probability of failure, $Pf$. Results showed that $Pf$ gradually increases with the increase of approaching flows on the street. Sensitivity analysis carried out revealed that water depth is the most significant parameter that governs the performance of the inlets. Results obtained are significant, especially for better design optimization purposes.

Soil moisture plays a significant role in hydrologic systems and agriculture by serving as an important input parameter in major hydrologic process modeling. As limited field studies on investigating soil moisture dynamics and flow processes under wheat cultivation are reported, especially in heterogeneous lateritic soils, the present study was conducted to understand the flow dynamics in a heterogeneous vadose zone under wheat cultivation. Proper field instrumentation was created, and detailed investigations were carried out to determine layer-wise soil physical properties as well as to monitor daily perched water table and moisture content in each layer during two wheat growing seasons. Further, a HYDRUS-1D model was developed to simulate the effects of wheat crop growth and irrigation on the vadose-zone flow dynamics. Analysis of the results revealed that the soil moisture at shallow depths up to 0.30 m shows significant temporal fluctuations due to plant water uptake and the percolation of water to deeper depths. At deeper depths, consistently high moisture content was prevalent throughout the crop growing season with little percolation beyond 0.30 m depth due to the presence of relatively impermeable layers at varying depths. Saturated moisture content was found to be the most sensitive model parameter. The HYDRUS-1D model simulated drying and wetting events reasonably well in the entire flow domain before and after the application of irrigation water except at deeper depths. Mostly downward water flux was found to be dominant after the 1.3-m deep soil layer with only a small fraction of water percolating beyond the 1.3-m soil layer, whereas significant upward water flux dominated in the upper soil profile. Results of this study can further aid in designing an efficient demand-based irrigation schedule for the wheat crop grown in the lateritic region, thereby helping in formulating an efficient irrigation management plan.

The scouring process near spur dikes could jeopardize the stability of riverbanks. Thus, accurate estimation of the maximum scour depth near spur dikes is crucial in river engineering. However, due to the complexity of the scour phenomenon around these structures, it has been a challenge to accurately estimate the maximum scour depth. Few efforts have been made to develop a machine learning (ML) approach for such a purpose. In this study, two novel multilayer stacked generalization frameworks are developed to model the scour depth near a spur dike in a uniform sediment condition. Stacked tree-based frameworks consist of three standalone ML approaches, including multivariate adaptive regression spline, multigene genetic programming, and kernel extreme learning machine as the first layer and the boosting regression tree (BRT) and bagging regression tree (BGT) as meta learners. A total of 186 data points were collected from previous experimental studies, and 32 flume experiments were further conducted under clear water conditions at the Indian Institute of Technology (IIT) Roorkee Laboratory in this study. The performances of the models were assessed using various statistical metrics [e.g., correlation coefficient ($R$), root-mean-square error (RMSE), and mean absolute percentage error (MAPE)], graphical criteria, and some existing empirical equations. The modeling results demonstrated that the stacked BRT and BGT frameworks were superior to all the standalone ML approaches ($R=0.9786$, $\mathrm{RMSE}=0.1654$, and $\mathrm{MAPE}=11.68$ for BRT; and $R=0.9742$, $\mathrm{RMSE}=0.1831$, and MAPE $=11.29$ for BGT). This finding was also confirmed by a comparison between the empirical correlations and the artificial intelligence models. In addition, the sensitivity analysis proved that the mean sediment size ratio ($L/d_{50}$) was the most influential variable in estimating the scour depth near spur dikes.

Sugarcane is one of the most important industrial crops grown throughout tropical areas. Sugarcane production is greatly expanding in developing countries like Ethiopia due to increasing demand for sugar. However, sugarcane is characterized by a long growing period and high crop water demand. Effective management of sugarcane requires accurate determination of its water requirements throughout the growing period. The aim of this study was to determine sugarcane water requirements and establish its crop coefficient. Sugarcane was grown on two non-weighable lysimeters to quantify the field water balance components from which actual crop evapotranspiration was calculated. A neutron probe was used to monitor change in moisture content per unit of time. The soil moisture in the lysimeters was managed such that optimum conditions were maintained to ensure unrestricted crop evapotranspiration. Reference evapotranspiration was estimated using climate data from a nearby station and the CROPWAT model. Sugarcane evapotranspiration ranged from 1.63 to $7.13\mathrm{mm}/\mathrm{day}$ during the early and peak growth stages, respectively. The growth stage-based crop coefficients were estimated as 0.42, 0.93, 1.26, and 1.05 during the emergence, tillering, grand formation, and ripening stages, respectively. When compared to Food and Agricultural Organization (FAO) of the United Nations references, the sugarcane crop coefficients in this study were 2%, 1%, and 30% greater during emergence, grand formation, and ripening, respectively, but 33% lower at tillering. Although these results were obtained from a single experiment, they can be useful as field measurement-based data are lacking in many areas of the region.

The adaptation of existing dams is of paramount importance to face the challenge posed by climate change and new legal frameworks. Thus, it is crucial to optimize the design of stilling basins to reduce the hydraulic jump dimensions without jeopardizing the energy dissipation in the structure. A numerical model was developed to simulate a US Bureau of Reclamation Type II basin. The model was validated with a specifically designed physical model and then was used to simulate and test the performance of the basin after adding a second row of chute blocks. The results showed a reduction in the hydraulic jump dimensions in terms of the sequent depth ratio and the roller length, which were respectively 2.5% and 1.4% lower in the modified design. These results would allow an estimated increase of the discharge in the basin close to 10%. Furthermore, this new design had 1.2% higher efficiency. Consequently, the modifications proposed for the basin design suggest improved performance of the structure. The issue of the hydraulic jump length estimation also was discussed, and different approaches were introduced and compared. These methods follow a structured and systematic procedure and gave consistent results for the developed models.

Bioinfiltration systems for stormwater management rely on the ability of the engineered media to adequately infiltrate, filtrate, and store water to reduce runoff volumes and improve water quality. However, the potential clogging of the soil over time due to the migration of fines and deposition of sediment and debris has raised concerns regarding system longevity. To quantify temporal and spatial changes in textural and hydraulic properties of bioinfiltration media infiltrating runoff from an interstate, a comprehensive field and laboratory study was completed for two sites over a two-year period. Despite observed sediment deposition within both basins, there were no statistically significant trends in the saturated hydraulic conductivity of the media over the study period. Soil core sampling and analysis confirmed fines did not migrate through the soil column. Susceptibility to future clogging of the well-graded, loamy sand used at both sites was evaluated based on the collected data and permeability and retention criteria commonly used in geotechnical design of graded filters. Based on the results of this study and the current literature, soils proposed for use in bioinfiltration systems should be evaluated for filter compatibility with the anticipated sediment load and include maximum limits on the plasticity index to help enhance system lifespan and reduce necessary maintenance.

Cross-section expansion can be a convenient solution to enhance the performance of stilling basins. However, under certain working conditions, the undesired phenomenon of flow instability can result in asymmetric flow with less efficient dissipation and high local velocity concentrations in the tailwater channel. This paper presents an experimental investigation on a recently proposed dissipator consisting of a series of cross beams, tested in various geometric configurations and under different hydraulic conditions. The effectiveness of the device is first analyzed in terms of flow uniformity and velocity in the channel bed while also providing a theoretical explanation of the observed dissipative mechanisms. Furthermore, in a second phase, the performance of the system is tested under variable tailwater conditions, with the description of the three-dimensional flow patterns observed in the downstream channel. The results suggest that the installation of this type of dissipator allows for the benefits of cross-section expansion while avoiding its damaging effects.