فصلنامه مهندسی منابع آب
پیاپی 51 (زمستان 1400)

This study focuses on developing a conceptual socio-hydrologic model to simulate community response and hydrology interactions in the Tashk and Bakhtegan lakes basin. There is a sharp decline in lake water levels due to agricultural development in upstream areas of Tashk and Bakhtegan lakes, along with droughts that occurred in the 2000s. This study demonstrates the potential of socio-hydrology modeling to describe complex human-water systems applying simple concepts and relationships. For the sociological module, two variables of community sensitivity and behavioral response have been chosen. For the hydrological module, the developed water balance model for dry catchments has been used. It is assumed that changes can be different in human priorities and community sensitivities in the upstream and downstream residents of the basin due to the basin extent and the differences in the region. The time period of the study is between 1996 and 2013. The results showed that the perceived level of threat to a community’s quality of life is low in the upstream sub-region of the basin, which has more rainfall and water resources. As a result, the preferences of its residents are toward using more water and land resources. But in the downstream sub-region of the basin, people have shifted their preferences for using less water and land resources, especially with environmental problems and scarcity of water resources causing a high level of threat to their quality of life.

Subsurface drip irrigation (SDI) is widely used in arid and semi-arid regions due to water saving. In order to investigate the moisture distribution pattern in SDI, the laboratory experiments were carried out in a transparent plexy-glass tank (0.5m *1.22m * 3m) using three different soil textures (i.e. medium, heavy and fine). The drippers were installed at 2 different soil depths (15cm and 30 cm). The emitter outflows were considered as 2, 4 and 4 lit/hr. Also, these experiments were carried out for two continuous and pulse irrigation systems. In pulse irrigation, the pulse cycles were considered 30-30, 20-40 and 40-20 min. The first number was the irrigation time (on) and the second number was the rest time (off) of the system in each cycle. The results of this research showed that moisture advance front with increasing the rest time move more horizontally for SDI with pulsed flow. Also, horizontal distribution of wetted front (for the same water volume of at the end of irrigation) for low emitter discharges was more than emitter with high outflow rate. As well as, the maximum depth of wetted front was related to emitters with higher discharge rate in the light texture, and in heavy texture is related to lesser outflow rate. The results showed that the horizontal distribution for pulse irrigation (20-40) was more than two other pulses (40-20 and 30-30) and continuous application.

Routing is one of the most sensitive parts of the design of power transmission lines. Any mistake in choosing a route can lead to high costs or costs for regional water companies at runtime or line operation. In this research, to solve the problem of determining the optimal route of water pipelines using spatial analysis, a multi-criteria decision making and raster-based shortest path algorithm were used from Ardak to Mashhad. For this purpose, firstly, the effective parameters in determining the route, including slope, geology, land use, residential areas, Waterways, roads, faults, and protected areas were determined and after weighting processes in AHP, TOPSIS and Fuzzy Logic methods, overlaid in the form of information layers in the GIS environment in order to generate cost mapping. Then, using the lowest cost algorithm in raster, the optimal path was determined. Finally, a comparison was made between the traditional way provided by the consultant and the proposed route with the lowest cost algorithm. The paths obtained from the lowest cost algorithm based on AND, GAMA, AHP, and TOPSIS were equal to 44.798, 46.755, 45.731, and 45.531 km, respectively. On the advised paths of the consultant, Route 1 has a length of 72.306, a suggested track 2 has a length of 63.108 and the third one was 48.690. Finally, the TOPSIS route model was selected as the best route due to the consideration of the forbidden areas.

Basically, dense flow is a two-phase flow that occurs due to the movement of a fluid in a different fluid of different densities. Laboratory research has been carried out on physical and hydraulic models of the Faculty of Engineering Sciences of Shahid Chamran University of Ahwaz. Flume contains three successive bends with three different relative curvature radiuses: r/b=2, 4 and 6, 8.5 m length, 20cm width and 70cm height and a mobile bed type of Polyastailen cover the bed. The results show, increasing the concentration of the inlet current, the flow velocity of the body flow increases on a mobile bed. The rate of increase in velocity depends on changes in the form of the bed the flow rate of the body will be reduced to about 19%. The velocity of the forehead has increased in the conditions of the mobile bed by forming the form of the bed. Also the elevation of the interface at the outer bank is in every case greater than the one at the inner bank. Due to increasing the relative curvature radius decreases elevation of the interface and transverse interfacial slopes. The maximum and minimum super elevations occur in r/b =2 and6, respectively. the transverse velocity decreases and the velocity increases in direct direction, which plays a significant role in reducing the slope of the water surface and the difference in height. Hence, the difference between the level of water in the third arc is very small.

Labyrinth weirs are structures designed for transferring large flows at low heads. In other words, labyrinth weirs are a particular type of nonlinear weirs used to control a flow as an economic and technical option. They are used when it is not possible to increase the capacity of a weir through increasing its width due to topographic conditions. These types of weirs enjoy a very high discharge capacity. As these types of weirs increase the effective length and following that the discharge efficiency, they can be used as dam weirs or water regulation structures. Considering the fact that there have been no comprehensive studies so far to investigate the weir discharge coefficient when the weir has a curved plan, in this research, some studies were conducted on trapezoidal arced labyrinth weirs with different arc radii and cycle lengths. Numerous experiments were performed using the physical modeling method to investigate the effect of the ratio of the inside apex width of the side weir cycles to the inside apex width of the middle weir cycle (w2/w1), the ratio of arc radius to the width of the middle weir cycle (R/w1), and the ratio of the length of a weir cycle to the width of the middle weir cycle (B/w1) on the weir discharge coefficient. The experiments revealed that by decreasing the inside apex width ratio of the weir cycles (w2/w1), the discharge coefficient shows an increasing trend up to 33%.

The purpose of this study was to investigate the effective mechanisms of drought crisis management from the viewpoint of the experts of the Ministry of Jihad-e-Agriculture of the province of Alborz. The present research this is a descriptive-correlational research. The statistical population of this research was 316professional agent from the Jihad-e-Agriculture Organization of Alborz Province. The sample size selected based on the Morgan and Morgan table of 183 people, and the sampling method was proportional to the simple random sampling method. The calculated alpha for the research questionnaire is 0.80. .The research data indicate that the variables of managerial factors are about 32.4, the variables of economic factors are about 31%, the variables of educational factors are about 28.5% and the variables of socio-cultural factors account for about 30.5% of the changes in the dependent variable of drought crisis management. The results of Factor Analysis of Drought Crisis Management Solutions in the field of agriculture in Alborz province showed that political-supportive strategies, management solutions, technical solutions, legal solutions, educational strategies and economic solutions are the priorities of the factors that have the highest share in the explanation. Drought crisis management strategies in the field of agriculture in Alborz province have been studied by experts. These factors account for 72.12% of the variance of all variables.

In many types of hydraulic structures, a considerable portion of the kinetic energy of the flowing water must be dissipated to prevent erosion of the channel downstream from structure. Various methods of energy dissipation have been used to achieve tranquil flow conditions. One of the most effective means of accomplishing the required energy dissipation is a hydraulic jump. The hydraulic jump can assume several different forms depending on the geometry of the channel boundaries.

A negative step with abrupt drop can change length of jump, sequent depths, hydrodynamic forces and other characteristics of the hydraulic jump. Also using Bed Roughness in stilling Basins is an effective method to increase jump efficiency and decrease jump length. In the present study, combination of rough bed and negative step is used to check the effect of this combination on hydrodynamic forces in stilling basins.

The results showed that the most critical area in terms of maximum hydrodynamic forces and cavitation in this type of stilling basins can be find in 10.44 <x / y1 <13.43. Where x is the distance from the beginning of the jump and y1 is the initial depth of the jump. It is also found that Pressure fluctuations increase at a certain distance from the edge of the jump and then it will decrease to lowest level. The experimental results here is reported, may be helpful in designing of stilling basins with negative step and roughed bed. Also, can be used for particular reference to the thickness of the concrete slabs required to ensure the stability of the linings.

The aim of this research is to predict the effects of cropping pattern changes on the water table level and electrical conductivity of an unconfined aquifer in the Ali-Abad region using a Bayesian Decision Network (BDN) as an integrated approach. A conceptual model framework illustrating the relationship among variables in the system was developed and three management scenarios of crop pattern (current condition, high water demand crops, and low water demand crops) were considered for the study area. Marginal probability, Conditional Probability Tables (CPTs) and total probabilities were characterized using observed data, results of CROPWAT model simulation, and expert knowledge. The Netica software was used to run the Bayesian model and to analyze the sensitivity of the model with two criteria namely reduction of variance and belief variance. The analysis shows that the probability of groundwater depletion occurring for low water requirement crops will be about five per cent less than that in the current condition. The probability of improvement in electrical conductivity for low water requirement crops will be about two per cent greater than that for the current crop pattern. The sensitivity analysis of the Bayesian model shows that the water requirement of crops plays an important role in unconfined aquifer's characteristics. The results demonstrate that the BDNs are capable to help planners for improved management of groundwater resources by predicting and displaying the effects of crop pattern changes on the quantitative and qualitative characteristics of unconfined aquifers in a probabilistic context.

Scour is among the most critical topics in river engineering. A large number of bridges around the world are destructed mainly due to ignoring the hydraulic function in the design of bridges. The use of roughness, collars, submerged plates, and protective piles are among the methods for controlling and reducing local scouring. This study investigated the effect of protective piles in controlling and reducing scouring around spindle-shaped piers. According to the experimental results, by installing 5 piles at an angle of 30˚ with a relative distance (L/D) of 0.5, scouring decreased by 20% relative to the pile-less spindle-shaped pier. This scour reduction can be attributed to the transport of sediments around the pile toward the pier and accumulation of sediments in the middle of piles and in front of the spindle-shaped pier. The other factor reducing local scour is the change in the flow regime and reduced velocity and vortices in front of the spindle-shaped pier. Moreover, as the relative velocity (V/Vc, the ratio of the flow velocity to the critical velocity) increased from 0.54 to 0.95, scouring increased by 165.4% on average. The water flow colliding the spindle-shaped pier and the formation of a downward flow cause scouring. An increase in the flow velocity also increases the vertical velocity and vortices and thereby scouring. The mathematical model simulated by Flow-3D is consistent with the physical model showing an acceptable error rate of 4.3%.

The presence of positive surges can cause bank destruction, bed scouring, and damages to structures such as bridge piers installed on the path. On the other hand, the remains and bridge pier destruction waste on the path affect velocity variations and flow surface fluctuations resulting from these surges and require careful investigations.

This study comprises an experimental analysis of the effect of present damaged and undamaged bridge piers on flow pattern variations during the generation of positive surges in sloped and horizontal channels. To this aim, ADV was utilized to help collect three-dimensional flow velocity data. Moreover, PIV was used to help make a comparison with ADV data results. Four distinct probes were incorporated for bathymetry in the horizontal and the sloped channels.

The obtained results were indicative of non-breaking undular surges generated in the horizontal channel and non-breaking and breaking undular surges formed in the sloped channel. In the sloped channel, the maximum velocity increase occurred with installation of two piers, which showed a 34.39% increase compared to that under the same conditions in the horizontal channel. Furthermore, the average water level variations due to the slope of the channel in cases without an element, with a damaged element, with an undamaged element, and with a combination of damaged and undamaged elements were respectively equal to 31.66, 32.70, 29.88, and 27.40%. In addition, the Reynolds shear stress values were also calculated in the sloped channel to be 7.6, 3.57, 1.38, and 1.68 times those in the horizontal channel.