Iranian Water Research Journal

Abstract Hydraulic jump is a type of rapid variable currents, which has surface turbulence and twisting of water from the beginning to the end, and is known as an energy-wasting phenomenon. In this research, the numerical simulation of hydraulic jump was done in the case of initial negative step of 3 and 6 cm, bed roughness of 2 cm and reverse slope of 1.5 and 3%. RNG and k-ε disturbance models were used in this research. Also, two types of uniform and non-uniform grids were used. According to the numerical modeling results, the RNG turbulence model calculated the turbulence of the flow field more accurately compared to the K-ε turbulence model. The statistical indices of NRMSE, R2 and d for the numerical simulation results of the water surface profile were obtained as 10.1, 0.993 and 0.994 respectively. Also, the values of these indices were calculated for the speed profile simulation results, respectively 16.36, 0.944 and 0.97. The error of the numerical model in calculating the values of the velocity profile was higher compared to the water level profile, which can be attributed to the severe flow turbulence and instantaneous velocity fluctuations in any vertical direction within the range of occurrence of hydraulic jump and intensification of air-water mixing. Comparison of the simulation results with the laboratory results of water surface profile, velocity profile, conjugate depth ratio, rolling length and hydraulic jump length and energy loss ratio shows the capability of the numerical model in the three-dimensional simulation of the free hydraulic jump flow field.

Abstract Abstract

Introduction:

Assessment of the quantity of underground water is of particular importance in water resources management. Using new methods, including meta-evolutionary algorithms, in estimating underground water tables changes, due to their speed, convergence and very high efficiency, leads to save money and cost reduction on water resources management. Climate change produced by air warming and increasing evaporation and transpiration from surface water resources, as well as increasing demand for water consumption on the one hand, and decreasing the rainfall and recharging the underground water sources on the other hand, has augmented the stress on groundwater resources, which conducted to the drop in the ground water table.

The reports of the International Commission on Climate Change indicates that the phenomenon of climate change has occurred in Iran in recent decades, also its severity and its consequences in the future are increasd. The purpose of this research is to evaluate the changes in the underground water level of Dasht-e Riz in Bushehr province in the south of Iran in the future under the influence of climate change. The study area is located in Jam city, 265 km from Bushehr (the capital of the province) and 25 km from the Persian Gulf. Dasht-e Rez watershed is located between 52˚00’ to 52˚18’ east longitudes and 27˚49’ to 27˚07’ north latitudes.



Methods:

Groundwater table and meteorological data of Dasht-e Riz from 1992 to 2020 were analyzed to determine the effect of temperature, rainfall on ground water table. The meteorological information collected from Jam synoptic station between 1992 and 2020. Reconstruction of the missing data of this station has been done by using the data of Bandardir and Asalouye synoptic stations, which are located in the vicinity of Jam station. The information for determining the hydrograph of underground water obtained from 16 observation wells. In order to determine the parameters affecting the changes in the groundwater table level of the Dasht-e Riz, the hybrid of meta-evolutionary Slime Mold Algorithm (SMA) and the Support Vector Regression (SVR) algorithm was used. It should be noted that by analyzing the determination coefficients, the results of the hybrid solution had the better results in comparison with support vector regression algorithm.

Coupled three-dimensional models of the general circulation of the ocean are used for introducing the climate change. Due to the dependence of the effects of climate change on the results of climate release models and scenarios, to achieve more favorable visualization in the future period the climate models presented in the sixth report are used due to their greater accuracy. For evaluating the climate change, the output of the MRI-ESM2-0 model from the set of available CMIP6 models under the SSP5-8.5 release scenario was used for the base period (1992-2020) and the future period (2050-2021). After simulation, downscaling was performed; using Lars WG-v6 model.



Results:

According to the results, the total monthly rainfall will decrease in the months of January, February, April, September, October, November and December and increase in the months of March, June, July and August, while the changes in monthly rainfall in May will not change significantly. Based on the obtained results, the monthly rainfall in winter, spring and autumn (wetter months of the year) will decrease and in the summer (dry months of the year) will be on increasing trend, which will lead to a 17.1% decrease in annual rainfall.

The error on estimating the changes in groundwater table level; using the support vector regression algorithm, the combined slime mold-support vector regression algorithm was 15% and 11%, respectively, which shows the better performance of the slime mold-support vector regression combined algorithm compared to the support vector regression alone.

The evaluation of the hydrograph of Dasht-e Riz underground water unit in the future period shows that the severity of the drop in water table level in the future period is due to the upward trend in the demand for water consumption due to the increase in evaporation and transpiration, as well as the decrease in water resources due to the decrease in precipitation. It will cause the intensity of the water level drop in the future period to occur faster than the base period. The water table drop in the future period will be 0.78 meters per year, which compared to the water table drop in the base period which is 0.75 meters per year, the water level drop is more severe in the future.

Abstract Introduction

Efficient utilization of water in the agricultural sector, or enhancing water productivity, is pivotal in mitigating the challenges of water scarcity in Iran. One of the ways to reduce water consumption and increase water productivity is by minimizing the evaporation of water from the soil's surface. subsurface irrigation is one of the methods that can reduce water evaporation from the soil surface. Using water below the ground surface and on the root environment in subsurface irrigation can result in proper moisture distribution and affect evaporation from the soil surface. Subsurface irrigation using geosynthetics or geotextiles is an innovative method in agriculture that helps improve water resource management and increase the efficiency of water use. This method, known as SSTI, can be applied to various soil types, from sandy to clayey, and offers numerous benefits. Among these benefits are the reduction of water, fertilizer, and herbicide consumption. In the SSTI system, water and nutrients are directly delivered to the plant root zone, which can contribute to increased plant performance and health. The use of geocomposite sheets in this system can be effective in the application of treated wastewater in subsurface irrigation, as the hydraulic conductivity of the geotextile mat differs from the surrounding soil and can improve the soil moisture distribution pattern. This, in turn, ensures that water is distributed more appropriately in the root development zone, thereby optimizing plant growth. The aim of this research is to investigate the impact of using geotextile mattress in subsurface irrigation systems on the pattern of moisture distribution.

Materials and Methods

This study was conducted at the irrigation laboratory of Shahrekord University using a physical model encompassing a one-cubic-meter volume with transparent Plexiglas walls. Geotextile mats, composed of geotextile sheets, were placed around the water pipes. Considering the permeability differences of the envelope sheets, an experiment with ten treatments was designed in silty clay soil. Soil passed through a number 10 sieve was used to fill the model. The model was fill with soil with several layers and compacted in such a way that the bulk density of the layers was uniform, ensuring the overall bulk density of the soil in the reservoir was consistent. The study was conducted as a factorial experiment based on a completely randomized design with three replications. The first factor was the depth of pipe installation at two levels (15 and 30 centimeters from the soil surface), and the second factor was the type of geotextile mat in five levels (two types of non-woven geotextile mats with a permeable bottom layer similar to the top layer, two types of non-woven geotextile mats with a less permeable bottom layer, and without envelope as the control). The inflow rate to the model was kept constant throughout the experiment using a float and a reservoir. Since initial moisture plays a significant role in soil moisture distribution, efforts were made to conduct all experiments at a uniform initial moisture content (equivalent to 4 percent by volume and air-dry soil).

Results

To investigate the impact of envelope type on soil moisture distribution, four key parameters were analyzed: maximum width and wetted depth, capillary rise, and overlap of the moisture front. The results revealed that incorporating geotextile mats around water pipes led to a significant increase of up to 70% in maximum wetted width, a decrease of up to 70% in maximum wetted depth, and a reduction of up to 95% in maximum capillary rise compared to sand and gravel treatments. Furthermore, elevating the mat installation depth from 15 to 30 centimeters not only further decreased capillary rise and wetted depth but also enhanced wetted width. The statistical analysis highlighted the significant impact of depth and envelope type as experimental factors at the 1% level. Geotextile treatments with sheets featuring a lower permeability coefficient exhibited reduced capillary rise, consistent with the findings on wetted width and depth. When the moisture front's arrival at the soil surface determined the cessation of flow, treatments positioned at a 15-centimeter depth did not allow sufficient time for moisture front overlap. In contrast, placement at a 30-centimeter depth facilitated appropriate overlap and minimized the wetted surface area, subsequently reducing evaporation. Among treatments positioned at a 30-centimeter depth, geotextiles with lower vertical permeability necessitated more time for the moisture front to reach the soil surface. Consequently, geotextile mattress crafted from materials with lower vertical permeability can support optimal horizontal and vertical expansion and they could be evaluated for landscapes, stadiums, and greenhouses under evaluation.

Abstract Introduction: Groundwater is a vital resource for human consumption, agricultural production, and the development of water-related industries, especially in arid and semi-arid regions. Groundwater and surface water resources provide approximately 60 and 40 percent of Iran’s total water supply, respectively, where the relative water consumption in the agricultural, urban, and industrial sectors is approximately 92%, 7%, and 1%, respectively. The construction of many dams on main rivers, along with water extraction, has reduced river flows, dried them up, and damaged river-dependent ecosystems. The inflow to Tashk and Bakhtegan lakes located in Fars province has decreased due to the construction of upstream dams and the use of river water for irrigation in the past decade, leading to the drying of these lakes in 2013. The over-extraction of groundwater by ~5.4 billion cubic meters per year during the 2002-2015 period has resulted in a decrease in groundwater levels (10-100 centimeters per year) in different regions of Iran, averaging 49 centimeters per year nationwide, damaging groundwater-dependent ecosystems in some areas. For example, Parishan Lake, which is mainly the result of the inflow of groundwater from nine springs, has experienced a decrease in water depth (about 5 meters during the 1995-2008 period) due to increased groundwater extraction around the wetland. The Jahrom aquifer in Fars province has also experienced a decrease in water level of approximately 0.75 meters per year, or three aquifers Aspas, Khosrowshirin, and Kamfiruz in the north of Fars province have respectively experienced a decrease in groundwater level of approximately 0.7, 1, and 0.35 meters per year due to over-extraction. Although groundwater is a vital source for human needs and consumption, it is also vital for preserving the environment. The main point in water resources management is the neglect of environmental water needs, in other words, all the water available in a river or aquifer is only considered for human consumption. However, a physical index recently presented by Naderi (2021) takes into account environmental needs and quantifies the level of water resources management based on the concepts of available water and water supply (water extraction). The aim of this study is to quantify the level of management (LOM) of aquifers in Zanjan Province under “normal” and “sustainable” management conditions



Methods: The study area includes eight alluvial aquifers of Zanjan Province (northwestern Iran) which are located between 47010’ to 5005’ E and 35025’ to 37010’ N. About 1.6% of the province’s area has a dry climate, 76% has a semi-dry climate, 20% has a Mediterranean climate, and 2.4% has a semi-humid to humid climate. The aquifers include Tarom, Zanjan, Mahneshan, Moshampa, Sojas, Zarrin-Tappeh, Abhar, and Qeydar, which have areas of 75.5, 1146.13, 30.06, 36.1, 501.7, 495.4, 657.6, and 699.2 km2, respectively. The LOM is quantified under “normal” and “sustainable” conditions. The difference between the two LOM values stems from definitions for existing groundwater sources. Sustainable groundwater originates from the aquifer’s own region, while normal groundwater originates from both the local aquifer region and adjacent groundwaters to meet the region’s water needs.

〖LOM〗_n=(〖AGW〗_n-TWS)/〖AGW〗_n (1)

〖LOM〗_s=(〖AGW〗_s-TWS)/〖AGW〗_s (2)

〖〖AGW〗_n=R〗_n-EFR=(I_p+I_r+I_s+I_irg+I_mi+I_net )-EFR (3)

〖〖AGW〗_s=R〗_s-EFR=(I_p+I_r+I_s+I_irg+I_mi )-EFR (4)

In the above relations, subscripts n and s represent normal and sustainable conditions, respectively. AGW is available groundwater, TWS total water supply, R the recharge of groundwater, EFR the environmental flow requirement, infiltration from precipitation (Ip), groundwater recharge from the river (Ir), groundwater recharge from runoff (Is), groundwater recharge due to irrigation return flow (Iirg) and municipal-industrial (Imi) water use, and net groundwater recharge from adjacent groundwaters (Inet).



Results: Alluvial aquifers of Tarom, Zanjan, Mahneshan, Moshampa, Sojas, Zarrinabad, Abhar, and Qeydar have experienced groundwater storage anomalies of 2.57, -25.61, 3.83, 0.82, -6.46, -9.52, -45.80, and -19.55 million cubic meters per year, respectively. Only the aquifers of Tarom, Mahneshan, and Moshampa have positive changes in storage volume. Results show that in the Mahneshan aquifer, normal management was positive (3 percent) but sustainable management was negative and close to zero (-0.1 percent). Therefore, the type of management is “pseudo-sustainable”. In the Moshampa aquifer, normal management was positive (2 percent) but sustainable management was negative (-9.7 percent). Therefore, the type of management is “pseudo-sustainable”. In the Tarom aquifer, normal management was positive (6.5 percent) but sustainable management was negative (-0.38 percent). Therefore, the type of management is “pseudo-sustainable”. In other aquifers, both normal and sustainable management were negative and indicative of the “mismanagement” class, so that normal and sustainable management in the Zanjan aquifer were respectively -9 and -41 percent, in the Sojas aquifer were -8.9 and -17.7 percent, in the Zarrinabad aquifer were -18.5 and -68 percent, in the Abhar aquifer were -30 and -106 percent, and in the Qeydar aquifer were -14 and -106 percent. Therefore, it is necessary to improve the status of water resource management, using various solutions such as wastewater treatment, education and increasing public awareness in optimal water consumption, reducing the cultivated area, increasing irrigation efficiency, and cultivating crops with less water demand to reduce groundwater abstraction in Zanjan Province.

Abstract The scarcity of water resources can be considered one of the most important problems that has impacted all aspects of people's lives in Iran today. Given the significance of the issue, in this study, the dynamic hypotheses within the water resource supply system were initially illustrated through a causal loop diagram. This was done using the tool of system dynamics, which has proven its utility in analyzing and simulating various socio-economic systems. Subsequently, a Stock Flow Diagram was developed, and after model simulation and validation, scenarios involving tariff and governance in relation to water resources up to the year 1420 were analyzed. The results showed that changing household water consumption tariffs will not have much impact on water resource stocks. However, as the agricultural and industrial water consumption patterns are expected to be modified in the long term, increasing tariffs for these sectors will have a significantly better effect on water resource management over a 20-year horizon. If government regulations regarding water-intensive industries, cultivated land expansion, and agricultural water consumption become 20% more stringent, assuming stability in other model parameters, underground water resources and reservoir water resources are projected to increase by 17% and 20% respectively by the year 1420.

Abstract The effect of temperature fluctuations on the growth and abnormalities of tubers and their unfavorable quality in a specific geographical area that are being relate to the climatic characteristics of the region and is largely beyond the control of farmers (Parvizi et al., 2011). However, by adopting the appropriate planting date in each region, it is possible to avoid the collision of growth stages by preventing damage qualify of the produced tubers and, at the same time, the better quantity of production would be accomplished (Hassanpanah and Hassanabadi, 2012; Siddique et al., 1990; Rabinowitch and Levy., 2001). In order to investigate the possibility of delayed cultivation of potatoes in Hamedan and also to compare with its usual cultivation in June on the amount of water consumption and the quantitative and qualitative yield of potatoes, an experiment was conducted during the two growing years of 2018 and 2019 at the Agricultural and Natural Resources Research and Education Center. Revenue implementation. In this experiment, three potato cultivars including Sante (medium-early), Arinda (early) and Banba (semi-late) cultivars with four planting dates; 1- June 15th (the usual cultivation of the region), 2- 1st of July, 3- 15th July and 4- 30th July were planted in the form of Splited Strip Plot design . The tape irrigation system used in this experiment. The measured traits included the time required to achieve 90% germination, the number of main stems per plant, the time of full coverage and flowering, total yield, the percentage of tuber deformity and secondary growth, the percentage of tuber dry matter and the efficiency of water consumption. Based on the results of compound variance analysis, we found that the effects of variety and planting date on all growth traits, total yield and water consumption efficiency were significant. The interaction effect of cultivar and planting date was significant in most of the growth traits as well as tuber yield and tuber dry matter percentage. The results of this research showed that the delay in planting date of potato has positive effects on the speed of germination and the acceleration of canopy formation. The speed of reaching full overlapping canopy with a difference of 7 days in delayed cultivation date (30th July) provides suitable conditions for better competition of potato crop with weeds and faster tuber formation. The lowest rate of secondary growth with an average of 6.00% related to the planting date of July 30 (delayed planting) and it showed a statistically significant difference with the other three planting dates at the 5% level of Duncan's test. By comparing the mean results, it was found that in all three cultivars, the average increase in tuber yield by planting on June 15 was greater than delayed cultivation (30th July) in three cultivars (with an average of 6.2%), although three cultivars showed different reactions. On the other hand, the efficiency of water consumption in delayed cultivation date (30th July) increased by 1.53 kg per cubic meter of water (27%) compared to regular cultivation (June 15). The results of this research showed that with the delay in potato planting date in Hamedan province, the critical stage of potato growth (tuber bulking) did not coincide with the sudden increase in temperature in the province (July and early August). This condition lead to reducing the amount of growth abnormalities in the tuber and increasing the tuber's appearance quality.

Abstract Introduction

Most regions in Iran are classified as arid and semi-arid areas. The management of water resources in the agricultural sector holds great significance as it is the largest consumer of water in the country. To effectively plan and manage these resources, it is imperative to possess adequate information regarding the water consumption across different agricultural products. Given the country's reliance on sweet lime products, and the limited research conducted in this area, determining the water usage in sweet lime orchards could prove valuable for national planning and decision-making. A thorough review of existing literature indicates a wealth of information on water requirements and the impact of various irrigation methods on citrus fruit yield worldwide. However, there is a dearth of research specifically focused on irrigating sweet lime trees under the guidance of gardeners. In Iran, the management of sweet lime irrigation has also received limited attention. Therefore, this study aims to quantify and evaluate the volume of water applied and the water productivity of sweet lime trees in the country.

Methodology

In this particular field study, the direct measurement of irrigation water volume and sweet lime yield was carried out in a total of 67 selected orchards located in the provinces of Fars and Hormozgan. The fruit yield was acquired over a span of three consecutive years, and the average yield was subsequently utilized in the subsequent analysis. The investigation into potential discrepancies in yield, irrigation water volume, and water productivity in the production of sweet limes was conducted through the utilization of analysis of variance. By closely monitoring the irrigation program of the gardens and assessing the cultivated area, the inflow of water to the garden was determined, subsequently allowing for the measurement of the volume of irrigation water employed by the sweet lime trees in each individual garden. The multiplication of the flow rate throughout the entire irrigation period in the season yielded the precise amount of irrigation water volume. Additionally, various factors such as the soil texture of the gardens, the electrical conductivity of both the soil and irrigation water, among others, were measured in each respective garden. The evapotranspiration of the sweet lime trees in each region was calculated by employing the meteorological data from the station closest to the project implementation area over the course of the last ten years, as well as the year of the research, using the Penman-Montieth methodology. The obtained results were subsequently compared to the calculated net required irrigation water and the values outlined in the National Water Document (NETWAT).

Results and Discussion

The outcomes revealed that there were significant disparities in the output, quantity of water applied, and indicators pertaining to water efficiency within the aforementioned regions. The average yield of sweet lime per unit area was determined to be 22.3 metric tons per hectare. The mean volume of irrigation water used and the total amount of water applied were found to be 14,192 cubic meters and 15,144 cubic meters per hectare, respectively. The mean water productivity in terms of irrigation water was estimated to be 1.70 kilograms per cubic meter. The weighted average water productivity considering both irrigation water and long-term effective rainfall amounted to 1.47 kilograms per cubic meter. Similarly, the weighted average water productivity considering both irrigation water and current year effective rainfall was calculated to be 1.60 kilograms per cubic meter. The proportion of irrigation water volume used in sweet lime orchards with respect to the overall water requirement in the selected provinces was found to be similar. In general, the average difference between the depth of irrigation water and the annual and long-term gross water requirement in the country was found to be -1 percent and +17 percent, respectively. Factors such as water and soil salinity, tree age, gardener literacy level, and soil texture were identified as some of the variables that influenced the yield, water productivity, and volume of irrigation water.

Conclusions

Accurate determination of the required water for plants and the volumetric delivery of water can yield highly effective results in terms of reducing irrigation water usage and increasing water productivity. Furthermore, the adherence to irrigation scheduling in sweet lime orchards has the potential to optimize the yield per unit of water allocated. When establishing or renovating sweet lime orchards, it is advisable to select cultivars that are resilient to cold and salinity, possess export capabilities, and expand the cultivation area in proportion to the available water resources.

Abstract Hydraulic jump is one of the important phenomena in hydraulic science and it is classified among fast variable flows. This phenomenon enables the consumption of excess water energy downstream of hydraulic structures such as overflows, rapids, and valves. In general, hydraulic jump has a characteristic in which the excess kinetic energy of the flow is lost. This important feature is used as an energy absorber downstream of overflows, valves, rapids, etc. Due to the importance of hydraulic jump in the last seventy years, it has been widely studied and comprehensive information has been published. The aim of these studies was to better understand the jumping mechanism and create relationships to predict its characteristics such as the length of the jump, the depth of the required footing, the amount of energy consumption, the distribution of the flow velocity, pressure fluctuations and the profile of the water level during the jump. Accurate estimation of these characteristics has helped to design more economical and safer energy consuming structures.Method: In this research, the hydraulic jump in the compound channel with floor roughness has been investigated using Flow 3D software. In this simulation, the composite cross-section is rectangular-rectangular with a length of 12 m, which consists of two sections, the main channel and the floodplain. The depth and width of the main channel are considered constant. The simulations are performed in two width ratios (wr), four relative depths (Dr) and three different roughness height ratios (nr). All simulations are performed at three different speeds. The arrangement of floor roughness is regular. The roughness of the floor is in the form of small cubes, which are located at a distance of 1 meter from the beginning of the channel. The depth and width of the roughness of the bottom of the main channel and flood plains are 6 cm. The height of the roughness of the bottom of the main channel is considered to be 3 cm, but the height of the roughness of the flood plains is 3, 6 and 9 cm according to the defined proportions. The distance between each roughness on the bottom of the main channel is 3 cm and the distance between each roughness on the bottom of the flood plains is 2 cm. The distance between each roughness group is 0.15 meters. Boundary conditions were applied on 6 cubic faces of the solution grid. The boundary conditions used in the simulation are such that the upstream boundary is in the form of flow velocity, the downstream boundary is in the form of outlet, the ymin side wall boundary is in the form of a wall (right floodplain), the ymax side wall boundary is in the form of a wall (left floodplain). the border of the side wall of the main channel was chosen symmetrically, the border at the bottom of the main channel and floodplains was chosen as a wall, and the border at the water level was chosen symmetrically.

Results: According to the results of the simulations, the presence of roughness has reduced the secondary depth of the jump compared to the case without roughness. So that in Silabdasht width of 18 cm and depth ratio of 0.3, roughness height ratio of 2 and speed of 3.5 m/s, the average secondary depth is reduced by 5.64% compared to the channel without roughness. But the increase in the width of the floodplain caused a decrease in the secondary depth of the jump by about 26.26%. The lowest value of the secondary to primary depth ratio of the jump can be seen in the relative depth of 0.7 and the roughness height ratio of 2. It was also observed that with the increase in the ratio of the height of the roughness, the length of the jump decreases significantly in small depth ratios. The length of the jump is reduced by about 10.98% in the lowest value of the roughness height ratio, the width of the flood plain is 18 cm, the speed is 5.3 m/s and the depth ratio is 0.3, and it is reduced by about 47.37% in the highest value of the roughness height ratio, the speed is 5 m/s and the depth ratio is 0.3 find Also, with the increase in the width of the floodplain, the jump length decreases in a constant roughness height ratio.

Abstract As a multiphase flow, the Density current is associated with a significant amount of suspended sediments from the river and the basin, and due to its speed and concentration, it also erodes and carries with it a part of the sediments deposited in the previous periods. This flow takes straight or winding paths in the trough of the river. Therefore, in this research, an experimental study of the effect of the relative radius to the width of the channel with ratios of 2, 4 and 6 on the profile of velocity and concentration was carried out using a Doppler velocimeter. By examining the effect of increasing the radius of curvature on the profile of the velocity of concentrated flow in the vertical direction at the end of the arc, it was observed that for a flow rate of 2.5 liters per second and an upstream concentration of 12.5 gr/liter, at a constant concentration and flow rate with a threefold increase in the radius of curvature, The speed in the central axis of the channel increases by 40% due to the reduction of the effect of centrifugal force. Also, the results show that by doubling the turbidity by 2.5%, the velocity profile of the thick flow at the end of the arch increases by 37%. The bed, the position of the maximum flow velocity, is moved towards the bed as the concentration increases.