Journal of Irrigation and Drainage Engineering

Real-world, multiobjective, reservoir optimization problems (MOOPs) usually have conflicting objective functions. Multiobjective evolutionary algorithms (MOEAs) have been applied to solve multiobjective optimization problems. Given that MOOP solutions cannot minimize or maximize all objectives simultaneously, it is difficult to determine Pareto optimal solutions (POS). This paper presents a comparative multimethodological framework that implements five multicriteria decision-making methods (MCDMs) to determine POS for a single-reservoir system with three objective functions. The Borda technique was successfully employed to rank the MCDMs’ solutions. The reservoir system’s release, storage, and generated hydropower were optimized based on the best-ranked MCDMs’ solutions. This paper’s methodology introduces practical computational framework for making robust decisions in complex reservoir operation problems and demonstrates its applicability.

In pressurized irrigation systems the total long-term costs can often be minimized by dividing the pipeline into segments of different diameters. To properly design such a system requires an accurate hydraulic analysis. In this study, an analytical procedure was developed to simulate the energy grade line along trickle laterals with dual pipe sizes. Appropriate equations were developed to accurately estimate several important design factors such as the total head loss ($J_{\mathrm{Tot}}$), the total required head at the inlet ($E_{\mathrm{in}}$) and the minimum pressure head along the lateral ($E_{\min }$). The methodology takes into account the effect of the number of outlets along each reach of the lateral, outflow nonuniformity, friction factor variation, velocity head changes, and local losses. Friction losses were evaluated using the power form equation of the Darcy-Weisbach formula. Local losses and velocity head change were both addressed by obtaining an average along the lateral constant coefficient which is a function of the number of outlets and the outflow at the downstream end of each reach. Two power functions were also used to estimate the outflow nonuniformity along each segment of the lateral. The accuracy of the proposed method is very high in all cases examined and the results tend to accurately follow the numerical stepwise solution. Assuming a uniform outflow for the proposed method results in accurate estimations of $E_{\mathrm{in}}$ and $E_{\min }$ but generally not of $J_{\mathrm{Tot}}$. The nonuniform outflow approach, on the other hand, calculates all three design parameters with a high degree of accuracy.

This paper develops a numerical model for the analysis of sediment transport in irrigated channels. The overland flow equation considers infiltration into the subsurface. The model solves Saint Venant and sediment continuity equations to analyze overland flow and sediment transport, while Richard’s equation is used to analyze subsurface flow. Saint Venant and sediment continuity equations are solved using MacCormack-scheme-based finite-difference method and Richard’s equation is solved using a mass conservative fully implicit finite-difference method. The model is validated by comparing model-predicted aggradation with experimental observations. The model is used to study the effect of infiltration on aggradation of a channel bed during sediment-laden flows. It was observed that infiltration significantly affects and alters the aggradation phenomenon and aggradation considering infiltration is found to be higher than that without considering infiltration. Among the different unsaturated soil parameters, the saturated hydraulic conductivity and initial dryness of the soil were found to be the main factors affecting the sediment transport in irrigated channels.

Green roofs are emerging as an effective technology for stormwater management and sustainable building in the United States as they evapotranspirate the majority of smaller rainfall events (typically 2.5 cm or less) at the source. The various design elements within a roof can enhance or inhibit evapotranspiration (ET), such as the drainage system. Research at Villanova University was conducted on the performance of an undrained (6 years, 2009–2014) and drained (2 years, 2013–2014) green roof. The undrained system evapotranspirated 68–88% of the total precipitation each year between April and November. The drained system evapotranspirated 62 and 56% of the precipitation for 2013 and 2014, respectively. The different drainage configurations dictated the amount of water available for ET; more water was stored yielding more ET in the undrained green roof. The media was able to become fully saturated allowing for the retention of 35 mm of water in the undrained system while the drained system could only reach field capacity (13.5 mm). Accordingly, there was less outflow produced from the undrained system than from the drained system. The lack of drain did not compromise performance during rain events.

The saline groundwater irrigation is an important problem in the arid and semiarid region because it can cause soil salinization and reduce crop productivity. The accurate spatial distribution of groundwater salinity can be helpful to managers and decision makers. In this study, the mapping of salinity risk through groundwater electrical conductivity (EC) irrigation was performed based on data collected from 88 wells in the Lower-Cheliff plain (Algeria). The EC data showed a normal distribution based on elementary statistics. The EC classified using Riverside method point out a high risk of groundwater salinity (Class C3) or very high risk (Class C4) for soil salinization. The EC estimated by ordinary kriging method (OK) revealed on one hand, an underprediction of a high value, on the other hand, an overprediction of low value. The methodology of nonparametric and nonlinear of indicator kriging (IK) was performed by three thresholds: $\mathrm{EC}>2.25$, $\mathrm{EC}>3$, and $\mathrm{EC}>5\mathrm{dS}/\mathrm{m}$. The map has been obtained from the combination of the local conditional cumulative distribution function (CCDF). The interpolated map by IK indicates the same overall spatial distribution of salinity with the one obtained by OK, enlightening differences in the shape and size of the area. The comparison between the groundwater EC estimated by OK and the one using IK demonstrates that IK has a better spatial prediction of salinity in terms of area and uncertainty. The groundwater salinity map was improved and accurately predicted by IK interpolation method.

It has been well documented in specialized literature that, under certain circumstances, the Clément’s first demand formula fails in estimating flow in water distribution networks. Through numerical examples, the authors show that the method fails when the number of hydrants supplied by a pipe is small or when the nominal flow rate of the hydrants is nonhomogeneous. In such cases, the normality hypothesis of the design flow rate random variable, an assumption needed by Clément’s formula, cannot be made. An alternative method for calculating the design flow rate as a nonnormal random variable is presented. The method works very well in all analyzed examples, mainly because the normality hypothesis is not required. The paper also provides a free-software R-script using freely available software that allows applying the proposed method to user-defined cases. The script helps to understand the method’s theoretical basis and can be used as a tool for checking the assumption of normality of data. Therefore, the program allows the applicability of Clément’s method to be checked and provides an alternative accurate solution.

Subcritical flow in a short expansion tends to become detached from its sidewalls and create turbulent eddies. This phenomenon can cause undesirable losses of flow energy and channel erosion. This paper numerically investigates the effects of a triangular hump fitted at the bottom of the expansion on flow separation reduction. The results are validated using available experimental data. This paper reports quantitative details of the velocity field, eddy structures, and flow streamline separation in expansions of different divergence angles under various conditions of the Froude number. The results show that the flow of water can separate along either of the two sidewalls, possibly due to bistability. The use of appropriate humps can effectively reduce separation and turbulent eddies because they force the flow to accelerate and hence create a favorable pressure gradient. The results from this paper are useful for the optimal design of expansions as an important part of irrigation and water systems.