Journal of Irrigation and Drainage Engineering

Optimal operation of reservoir systems is a challenging task in water resource management, involving stakeholders with different utilities. These utilities are conflicting, especially in a multireservoir system when the number of stakeholders increases compared to a single-reservoir system. A reservoir system with hydropower energy generation and supplying downstream demands is an example of these challenges. An appropriate objective framework can improve mitigation of stakeholder conflicts. This paper considers a 1-year optimal operation of a multireservoir system, with two parallel upstream reservoirs and a downstream reservoir in series. System objectives are hydropower energy generation as well as supplying downstream demands. Existing conflicts of this system are determined in single-objective reservoir operation models. The mathematical form of objective functions can limit utility risk in multiobjective problems. To overcome impacts of existing conflicts, a simulation model has been coupled with the weighting method and Nash equilibrium in multiobjective models. Results show that although the calculated objectives using the Nash equilibrium are less (worse) than the maximum (best) values of the objective function with the largest weight for the first (highest) objective priority using the weighting method, in two parallel reservoirs the values of the objective function are larger (better), about 70.83 and 54.17%, respectively, for hydropower energy generation and supplying downstream demands objectives. Moreover, these objectives calculated by the Nash equilibrium are 58.33 and 50% better, respectively, than same values by the weighting method in series reservoirs. Thus, utilities were significantly balanced and increased from the worst (minimum) utility values by the Nash equilibrium. The Nash equilibrium increases considerably the reliability value for all stakeholders at the same time.

The reliable volumetric distribution of fertigation is vital for sustainable precision agriculture because it not only evenly distributes water in the spatial region where it is needed but also ensures rhizosphere nutrient utilization efficiency, electrical conductivity, and pH, thus yielding better production and reduced environmental emissions. We evaluated the supply delivered by two and four manifolds from a self-compensating antidrain dripper-emitter with flow rates of 2, 3, 4, and $8\mathrm{L}/\mathrm{h}$. Spikes with regulators (T1) and without regulators (T0) were tested. Connecting multiple manifolds to a single dripper with T1 spikes is not recommended. Drippers with low flow rates of 2 and $3\mathrm{L}/\mathrm{h}$ are not suitable for multiple distribution, but drippers with flow rates from $4–8\mathrm{L}/\mathrm{h}$ having two or four manifolds with T1 spikes produce adequate fertigation distribution for precision agriculture ($\le 5\%$, coefficient of variation percentage). The combination of an $8\mathrm{L}/\mathrm{h}$ dripper with four or two regulated manifold lines supplies fertigation distribution homogeneity equivalent to that produced by four $2\mathrm{L}/\mathrm{h}$ drippers or two $4\mathrm{L}/\mathrm{h}$ drippers with only one manifold, respectively.

Due to construction, operation, and maintenance difficulties, usually installing very wide sluice gates in open channels is not recommended. Instead, multiple parallel gates have been used in such circumstances, which generate parallel jets. The free hydraulic jump established downstream of two vertical sluice gates with different openings was investigated theoretically and experimentally in this study. The ADV technique was used to record the flow velocity at the tailwater section of a rather large-scale experimental setup. The impact of highly non-uniform velocity distribution of the tailwater section was incorporated in the momentum formulation to develop a relationship for accurately determining the conjugate depth of such a practical case. It was indicated that the momentum correction factor plays a key role to accurately determining the conjugated depths, and it should not be neglected. Considering $y_0$ as the upstream depth and $y_2$ as the tailwater depth, the compiled data of the classical and parallel jets hydraulic jumps revealed that for a given Froude number, higher values of the ratio $y_0/y_2$ are required to establish a free hydraulic jump as the gate opening ratio increases. Furthermore, a proper formula was developed to determine the head loss through free parallel jets hydraulic jump.

A new method for the isolation of the time interval in which cumulative double ring infiltration data strictly represents the one-dimensional (1D) infiltration is proposed. The infiltration time necessary for the wetting front to reach the bottom edge of the cylinders can be determined graphically by visual observation of cumulative double ring infiltration data, for both inner and outer cylinder, expressed in the form of a recently proposed 1D linearized infiltration equation. Afterwards, sorptivity, $S$, and saturated hydraulic conductivity, $K_s$, can be estimated by fitting the same equation on the double ring cumulative infiltration data until the specific time was graphically found. After the theoretical analysis, the proposed method was tested using numerical double ring infiltration data [HYDRUS-2D (two-dimensional)/3D (three-dimensional)]. The numerical results indicated that the proposed method provides parameter estimates for $S$ and $K_s$ of acceptable accuracy for the four selected soils that cover a range of soil hydraulic spectrum. Preliminary experimental validation of the proposed method is also presented based on experimental infiltration data derived from a controlled double ring experiment in laboratory conditions for a soil-sand mixture.

Construction and development activities can generate new sources of water pollution by increasing storm-water runoff and erosion. Wattle ditch checks may be used on construction sites to mitigate channelized runoff by impounding water, reducing erosive forces associated with runoff, and creating favorable conditions for sedimentation. This research was conducted at the Auburn University Erosion and Sediment Control Testing Facility (AU-ESCTF) to comparatively analyze eight different wattles composed of wheat straw, excelsior, or synthetic materials to understand the effect materials and dimensions have on wattle performance. This study showed that for a flow rate of $16\mathrm{L}/\mathrm{s}$, all three materials performed significantly differently. However, as flows increase to 32 and $48\mathrm{L}/\mathrm{s}$, the excelsior and wheat straw wattles performed similarly when considering hydraulic performance and product density. The synthetic material performed significantly different by impounding more water under all flow conditions even though it was 66 and 147% less dense than the excelsior and wheat straw wattles, respectively.

The hydraulic performance of large-diameter gated fluming, commonly used in furrow irrigation, was investigated using computational fluid dynamics (CFD). The continuity and the momentum equations governing the fluid in the system were solved numerically for a steady incompressible and turbulent flow using a realizable software model. The CFD results were compared with the laboratory measured results and those obtained using a hydraulic simulation model. The CFD results showed a good correlation with the measured data and those generated using the software. The velocity head in the pipeline had no influence on the magnitude of the outflows possibly due to the unique shape of the outlet. The pressure head recovery across the outlets was greater than the energy loss along the pipe; hence, the pressure and discharge increased towards the downstream end. The CFD approach was found to be an appropriate tool for detailed analysis of the hydraulic characteristics of gated irrigation pipelines.

This paper aims to assess the necessity of updating the intensity-duration-frequency (IDF) curves used in Portugal to design building storm-water drainage systems. A comparative analysis of the design was performed for the three predefined rainfall regions in Portugal using the IDF curves currently in use and estimated for future decades. Data for recent and future climate conditions simulated by a global and regional climate model chain are used to estimate possible changes of rainfall extremes and its implications for the drainage systems. The methodology includes the disaggregation of precipitation up to subhourly scales, the robust development of IDF curves, and the correction of model bias. Obtained results indicate that projected changes are largest for the plains in southern Portugal (5–33%) than for mountainous regions (3–9%) and that these trends are consistent with projected changes in the long-term 95th percentile of the daily precipitation throughout the 21st century. The authors conclude there is a need to review the current precipitation regime classification and change the new drainage systems towards larger dimensions to mitigate the projected changes in extreme precipitation.