Journal of Irrigation and Drainage Engineering

The Merus ring which is made by Merus Company in Germany is a new device that can be installed on a feed pipeline to reduce emitter clogging in trickle irrigation. Merus technology works using specifically modulated molecular oscillations or lattice oscillations and is not based on the use of fields created by electric coils or magnets. This study was performed in a field belonging to Isfahan University of Technology (Iran) to investigate the effects of the Merus ring on emitter clogging. Two main treatments of irrigation water, with and without the Merus ring, and three subtreatments of irrigation water salinity were used. The results showed that the irrigation water treatment had a significant effect on average emitter discharge at the 1% level. The average emitter discharge was higher for the treatment with the Merus ring compared to the treatment without the Merus ring. For both irrigation water treatments, the average emitter discharge decreased during the experiment, but the decrease was higher for the treatment without the Merus ring. Moreover, the irrigation water treatment had a significant effect on the distribution uniformity of the emitters at the 5% level. The distribution uniformity was higher for the treatment with the Merus ring compared to the treatment without the Merus ring. Therefore, application of the Merus ring is recommended to achieve lower emitter clogging, higher distribution uniformity, and better irrigation performance.

Reservoirs are infrastructures that play an important role in supplying water. Hydrological and meteorological parameters, as the most important elements in reservoir systems’ simulations, are uncertain. Thus, such uncertainties must be considered in integrated water resource management. This paper includes (1) generation of artificial time series based on probabilistic statistical models; (2) operation policies of hydropower reservoir systems; (3) analysis of risk and uncertainty of a reservoir system; and (4) development of performance indices for evaluation of hydropower reservoir system efficiency. To evaluate the effects of inflow uncertainty on the performance of a hydropower multireservoir system, this paper uses Monte Carlo simulation (MCS). Periodic stochastic models are used to generate different inflow time series. The generated time series are then used to run simulation and optimization models considering five scenarios. Subsequently, probability distributions of performance indices (volumetric reliability, time-based reliability, vulnerability, and resiliency) are extracted for each scenario. Moreover, the uncertainty of each parameter is measured by the coefficient of variation. Results show that the use of an optimization method to increase hydropower multireservoir system performance that considers inflow uncertainty yields the best volumetric reliability and vulnerability of management scenarios considered. The best values of temporal reliability and resiliency are obtained in single hydropower reservoir simulation and hydropower multireservoir simulation, respectively. In contrast, inflow uncertainty has the least effect on volumetric reliability (about 2%) and the most effect on resiliency (about 18%).

The governing equation for kinematic wave (KW) flow on a diverging alluvial fan is derived and presented with comparison with observed data. The key factors to describe a diverging KW flow are found to be the angle of apex, radius of alluvial fan area, ground surface slope, and rainfall intensity. The sensitivity tests indicate that under a specified condition, the rectangular KW flow is the enveloping curve for all diverging KW flows. The wider the angle of apex, the closer the diverging KW flow becomes similar to the rectangular KW flow. The analytical solution derived in this study provides the time to equilibrium and the peak flow on the diverging KW hydrograph. Both parameters are important for peak flow predictions. The new equation derived in this study offers a deterministic approach to define the base flood flow and the corresponding floodplain boundaries on the alluvial fan. It is believed that the approach outlined in this paper presents a significant improvement to the current practice on alluvial floodplain hydrology and hydraulics.

The quantity and quality of drainage water in areas with shallow and saline groundwater changes over time until it reaches a balance. The balance time is fairly long and depends on the characteristics of the shallow aquifer. Therefore, it is very important to simulate such phenomena in order to manage drain effluent, especially when it is supposed to discharge into the environment. In this paper, the system dynamics technique was used to simulate the performance of a drainage system in the unsteady state condition. The study used the system dynamic programming tool Vensim. The model developed in this study is capable of predicting many hydrological variables such as water table fluctuation, drainage discharge, and the salinity of drain water and ground water. The model was validated using data collected at a tile-drained experimental site irrigated with shallow ground water located in the Khuzestan province of Iran. The results show that the standard error values in determining accuracy of simulated water table level, drainage discharge, and salinity of drain water are 14.4 cm, $0.43\mathrm{L}/\mathrm{s}$, and $2.8\mathrm{dS}/\mathrm{m}$, respectively. A sensitivity analysis was done to determine the response of simulated results to changes in model parameters. The results indicated a good agreement between the observed and simulated variables, and the model can be used to manage and control saline drainage water and also to prevent environmental damage.