نشریه پژوهش های حفاظت آب و خاک
سال سی‌ام شماره 4 (مهر و آبان 1402)

Global warming cause changes in temperature variables and consequently increase in the occurrence of extreme events like as floods and droughts, result from extreme weather in most cases; Therefore, it is important to study and investigate the future changes of extreme values of meteorological and hydrological parameters, including temperature, more than the average or median value. Therefore, the purpose of this research is to investigate the effects of climate change on the trend of seasonal changes in extreme temperatures (very high and very low values) in coastal stations of Mazandaran province based on CMIP6 models and quantile regression method.

In this research, in order to investigate the trend of extreme values of temperature in Mazandaran province for the future periods, the output of the sixth generation of climate change models (Coupled Model Intercomparison Project phase 6, CMIP6) was used. For this purpose, minimum and maximum temperature of 4 main synoptic stations of the province, including Babolsar, Qarakhil, Ramsar and Nowshahr, and also the output of the NorESM2-MM climate model from the CMIP6 in near future (2026-2055) and far future (2071-2100) at three optimistic (SSP126), moderate (SSP245) and pessimistic (SSP585) scenarios was used. In order to downscaling climate model data at the studied meteorological stations, various methods in the CMhyd downscaling software were used, and the Temperature data output for the method that had higher accuracy, was selected to analysis of trend. In the next step, the quantile regression method was used to investigate the seasonal trend of temperature extreme values and the results were analyzed.

The results of downscaling using different methods have shown that the Variance Scaling method has the best performance among the available methods in CMhyd. In general, the results show a positive temperature anomaly (annual temperature increase compared to the base period in SSP126=1.3, SSP245=2.56, SSP585=3.2 oC) in Mazandaran province in all months of the year until the end of the 21st century. The intensity of the anomalies is higher in the warm months than in the cold ones. Under the optimistic scenario, the extreme values of the temperature variables in the spring and autumn seasons will decrease by a maximum of 1 degree per decade in the distant future. However, the average minimum temperature is increasing in all scenarios (including the optimistic scenario) and the decrease is only predicted for extreme values. But under the average and pessimistic scenarios, there will be an increase in the temperature extreme values in all seasons, so that its intensity will be greater for the pessimistic scenario and in the spring season (0.15 oC per year).

According to the results, it concluded that the significant increase in extreme temperature during the day and night, especially in the warm months of the year, will increase evapotranspiration, and along with the decrease in rainfall in the hot months, it will cause a decrease in water resources in different parts of Mazandaran province and pressure on the groundwater. Therefore, it is very important to formulate and implement appropriate management programs according to the needs of each region, in order to adapt to extreme temperatures and their adverse consequences.

Due to several factors, including anthropogenic global warming, drought is increasing in many arable areas which is one of the major threats to global food security. Abiotic stresses such as water deficit severely reduce crop productivity. Using strategies subsurface irrigation with porous clay capsules and natural nanobiochar amendment could be pivotal in reducing water and nitrogen fertilizer inputs as well as the effects of abiotic stresses on plants. Biochar addition to soil may improve soil physical and chemical characteristics. Soil water retention in the root zone enhances under the same irrigation schedule following biochar application. Biochar could improve plant access to soil nutrients and pivotal in reducing fertilizer inputs to agricultural soils.

Greenhouse experiments were conducted in two years (2019 and 2020) on broccoli planted in sieved and non-sieved samples of a loam soil amended with natural nanobiochar (i.e., 0 and 10% by weight) under three irrigation regimes (i.e., 100, 75, and 50% of full irrigation) and two levels of nitrogen fertilizer (i.e., 225 and 300 kgha-1 N). The irrigation system was porous clay pitcher subsurface irrigation. The full irrigation (FI) treatments were watered to refill the pore space in the rooting zone to the field capacity (100% FI), while in deficit irrigation treatments plants received 75% of the full irrigation (75% FI) or 50% of the full irrigation (50% FI). Fertigation treatments included two levels of N fertigation (i.e., 225 kg N ha-1 and 300 kg N ha-1) in the seedling, vegetative growth and green head stages were applied. Physiological and morphological traits of broccoli including secondary head fresh and dry weights, secondary head density, concentration of nutrients, total chlorophyll and leaf proline were investigated.

Plants exposed to deficit irrigation and nitrogen fertigation presented a significant decrease in head fresh and dry weights, head density and also total chlorophyll, while an increase in the leaf proline content was observed. The application of NNB in soil mitigated the drought and nutritional stresses effects on the morphological traits. The results showed significant effects of the natural nanobiochar application in sieved and none-sieved soils on head fresh and dry weight, head density, total chlorophyll and leaf proline for both seasons (2019 and 2020). Natural nanobiochar addition to both sieved and non-sieved soils improved the head fresh and dry weights, head density, and total chlorophyll content. Moreover, it significantly reduced the leaf proline of broccoli plant under deficit irrigation and nitrogen fertigation. The highest values of fresh and dry weight, head density and calcium, magnesium and chlorophyll concentrations were 99.26 g, 39.79 g, 0.92 g cm-3, 5.96 mg g-1, 3.52 mg g-1 and 2.52 mg g-1 in SNAS+NR2+FI, NNAS+NR2+FI, NUS+NR2+FI, SNAS+NR2+FI, SNAS+NR2+FI and NUS+NR2+FI treatments, respectively. As well as, the lowest value of leaf proline was 0.08 µmol g-1 in NNAS+NR2+FI treatment.

Our study demonstrated some of the beneficial effects of natural nanobiochar as an organic amendment for promoting crop productivity. Hence, the integration of natural nanobiochar addition along with deficit irrigation and low N fertigation condition could be considered as a viable and optimum approach in terms of water and fertilizer saving, yield and cost. Thus, the combination of this technique and sub-surface irrigation with the porous clay pitcher system will particularly be useful in arid regions that frequently suffer with water shortages condition.

The increase in the human population and the growth in water consumption on one hand, and the rise in sewage production on the other hand, have led to the expansion of environmental pollution threats. The objectives of the present study include launching a pilot project for the localization of knowledge in the design of artificial wetlands in accordance with the quantitative and qualitative conditions of domestic sewage in Iran (specifically, the dormitory of the University of Agricultural Sciences and Natural Resources in Sari) and investigating the possibility of replacing wetland systems with conventional domestic sewage treatment systems in the country.

This study was conducted at the University of Agricultural Sciences and Natural Resources in Sari, involving the construction of six artificial wetlands, each with a length of 3 meters, width of 2 meters, and a height of 1.5 meters, using reinforced concrete. One of the ponds was excluded from the system due to leakage. Inside the ponds, artificial filters at different depths (1 meter: d1 and 1 meter and 30 centimeters: d2) and plant filters (Phragmites australis: p1 and Arundo donax: p2) were filled and planted. D10 and the coefficient of unifo rmity (CU) of the substrate materials were obtained as 2 millimeters and 3.625, respectively, from the grain size analysis. The hydraulic conductivity and porosity of the substrate were 2.523 cm/s and 39.2%, respectively. The specific surface area (SSA) of the substrate materials was calculated as 1.336 m²/kg (2245 m²/m³ of substrate materials). The effluent from the septic tank of the dormitory's baffled septic tank was injected onto the beds after a settling and dilution stage using a pump. In the initial loading, the beds were submerged below the surface, and a three-day retention time was allowed for the first sampling. Quality parameters of the wastewater, including biochemical oxygen demand (BOD), chemical oxygen demand (COD), total suspended solids (TSS), fecal coliform (FC), and total coliform (TC), were monitored to assess the performance of the treatment system.

Although the injected wastewater was diluted up to 25%, a significant removal efficiency of 51 to 55, 41 to 79, 74 to 89, 70 to 95.3, and 78 to 95 percent was achieved for BOD, COD, TSS, FC, and TC, respectively, in different treatments. Among the treatments, the weakest performance was associated with treatment P1D2, while the best purification performance was observed in treatment P2D1. This indicates the dominance of the physical characteristics of the systems at the beginning of the startup period on the purification performance. However, the initial performance of the treatment system was very promising and the removal of some parameters such as TSS and FC was at the average level of a full-fledged wetland treatment system.

This wastewater treatment technology is recommended for all managers and experts in the country's wastewater industry, especially in rural areas with inexpensive land and a population of fewer than 5000 people. These conditions encompass all towns, universities, military barracks, and military facilities as well.

The occurrence of phenomena such as surges in complex devices such as turbines, and problems caused by neglecting safety precautions, may result in significant economic damage and losses to the transmission system. On the other hand, electricity production is a key factor in the economic and social development for developing countries. Recently, institutions involved in electricity supply have recommended pump as turbine projects as hydroelectric power plant for supplying electricity to rural areas due to their economic benefits. The issue under investigation in this study is the effect of pump shutdown on surge occurrence and its effects on the water transmission line.

The case study project is the water transmission line to the city of Masjed Soleyman located in the northeast of Khuzestan province, Iran. In this study, by using WaterGEMS software, the route of the transmission line, the type and diameter of the pipes, pressure relief valves, tanks, etc., have been defined and modeled in steady state. After processing the line in steady state, in order to investigate the replacement of the PATs with pressure relief valves and its shut-down effect on the water hammer phenomenon created in the transmission line, the model created in WaterGEMS is called in the Bentley HAMMER CONNECT software to analyze the unsteady state condition. The phenomenon of surge has been investigated in three scenarios as follows: The first scenario involves studying the flow conditions in a steady state without any changes in the transmission line. The second scenario involves replacing the pressure relief valve at kilometer 054+0 from the Tang-e Mo reservoir with a reverse pump. The third scenario involves replacing the pressure relief valve at kilometer 700+3 from the Tang-e Mo reservoir with a reverse pump.

When the pressure relief valves are working, the flow velocity in the pressure relief valve in 3+700 km, equivalent to 2.07 m/s, and the pressure before the pressure relief valve is equal to 157.7 meters of water and reaches 20 meters of water. Also, in the pressure relief valve 0+054 km from the reservoir, the speed is 2.1 m/s and the pressure decreases from 104.77 m to 13.2 m of water, respectively. For second scenario, in the first pressure relief valve, 91 meters of pressure is wasted. In this case, the PATs with turbine flow and pressure have replaced the existing pressure relief valves. The inlet and outlet valves of the first PAT are closed in 20 seconds and the flow through it is reduced to zero. Third scenario considers the water hammer impact resulting from shutdown of the PAT (at 3+700 km) on the transmission line. 137 meters of pressure is wasted in the second pressure relief valve. Also, the flow through it is 580.189 liters per second. In this case, the inlet and outlet valves of the PAT are closed in 20 seconds. It is necessary to explain that if the valves of the PAT (at 3+700 km) are closed, the downstream flow will also decrease; But due to the bypass of the PAT, the input flow to the downstream pumps does not reach zero and the pumps do not exit the circuit.

The results indicate that the occurrence of the surge due to the failure of the PAT(s) installed in the transmission line, despite the creation of positive and negative pressure waves in the transmission line, does not cause serious disturbance in the pipeline. It is also concluded that the thickness of the steel material selected for the pipeline has the required strength to withstand the maximum and minimum pressures.

Flood is a phenomenon during which the water fills the main channel of the river and spreads on to the floodplains. In some natural rivers as well as artificial canals in cities may be more than one floodplain flank the main channel, which is called multi-stage compound channels. In these channels, when the flood occurs and the main channel is filled, the first floodplain is activated, and then when this floodplain overflows, the second floodplain is activated immediately. One of the hydraulic aspects of these channels is the stage-discharge relationship, which is used to estimate the flow discharge for any given flow depth and hence is an important tool in the river design and management during floods. In this study, the one-dimensional model of interacting divided channel and two-dimensional model of Shiono and Knight, which were previously proposed to calculate the flow discharge in classic compound channels, are developed for multi-stage compound channels.

For one-dimensional model, using Newton's second law and by considering into account the apparent shear stresses at the interface of the main channel and the first flood plain, as well as the interface between first and second floodplains, a linear equation system was derived to simultaneously estimate the average flow velocities in adjacent flow compartments of these sections. Huthoff et al. equation was used for the involvement of apparent shear stresses in the interfaces. In this method, the momentum exchange coefficients were calibrated based on the laboratory data from Singh (2021) in a three-stage rectangular compound channel and using the nonlinear generalized reduced gradient optimization algorithm. To derive the semi two-dimensional model of Shiono and Knight, by depth integrating of the Navier-Stokes equations, a differential equation was obtained in terms of shear stress. Then by applying several appropriate assumptions for Reynolds stresses and secondary flows, a simple equation was obtained in terms of depth-averaged velocity. This equation was solved numerically using finite difference method.

The results of the one-dimensional flow interacting model showed that this method has a good efficiency in estimating the total flow discharges with an average and maximum error of about 2.6 and 5.7 percent, respectively. Meanwhile, the vertical divided channel method which is widely used in water engineering packages, does not provide reliable results with an average error of 9.1% and a maximum error of 17.4%. The results of the numerical solution of Shiono and Knight model showed that there is a good agreement between the observed and calculated lateral velocity distributions. It was also found that the effect of eddy viscosity and secondary currents in this channel is significant and should be considered. The mean and maximum error of this model in estimating the total flow discharges was 2.4% and 4.1%, respectively.

The results of both one- and two-dimensional models proposed in this research showed that these models have a suitable ability to estimate the total flow discharge as well as the subdivision flow discharges in multi-stage compound channels. Investigations showed that in terms of the intensity of turbulence and the strength of the secondary currents, the interface plane between the main channel and the first floodplain is much more affected than the interface between first and second floodplains.

The complex knowledge of local communities on the full cycle of disaster risk management has been proven valuable in various researches. However, the scientific literature still lacks studies that examine how to use Local Knowledge (LK) and the local people capabilities for crowdsourcing in Flash Flood Early Warning Systems (FFEWS) studies. Hence the main target of this research is investigation on the capacity of crowdsourcing for FFEWS and identification of Flash Flood Hotspots (FFHs) by LK across a flood prone area in northeast of Iran.

In this study, a questionnaire with three different themes was designed. The first theme was related to the individual characteristics as independent variables, the second theme addressed the residents’ LK in determining the FFHs, the type and the predominant time of the flood occurrence in the region, through asking open ended questions with short-answers. The last theme addressed the assessment of people's capacity in Flash Flood Crowdsourcing (FFC), through asking questions with a Likert scale of 0-5. The face-to-face questionnaire administration mode was used for public survey through conducting oral interviews and live discussions.

The results showed that there was no significant correlation between the individuals’ characteristics and their willingness and motivation to participate in FFC. Comparing residents’ LK with the 31-year flood report and literature review showed that the residents’ LK about the flood occurrence location, time and type on a local scale was very promising. The research results indicated that the respondents show highest level of willingness for participation in the release of flood warning messages with an average score of 4.23 and the most important motivating factor for their willingness to participate was introduced saving relatives, fellow villagers, and human being from flood hazards with an average score of 4.84.

In most of previous studies that have focused on the development of FFEWS, very little attention has been paid to understanding the needs of citizens and promoting their participation. In fact, there is a research gap regarding the method of citizen’s participation and their potential support for FFEWS. Hence in this research, an attempt was made to take a small step towards filling this gap by investigating LK, motivation and willingness of local residents to participate in various aspects and steps of FFEWS. Our findings indicate that involving local people in FFEWS has various unknown aspects that should be explored through more extensive and detailed studies.

Gibson et al. (2010) modeled the COWLITZ river considering the moving bed and used the HEC-RAS model for simulation. They did the modeling for the last 20 miles of the river because the possibility of flooding due to sedimentation was higher in this area. The purpose of this study was to evaluate the effects of sedimentation on the increase of flood risk in the long term. The Laursen-Copeland relationship was used in the sediment calculations because the sediments ranged from very fine sand to large rubble. They also stated that the ability to add bed particle size in 20 different classes has been added to the HEC-RAS model in version 4.1. The geographic location of this research is based on the UTM geographic system, around 33'22'32' to 32'45'17 north latitude and 40'22'48' to 48'57'19 east longitude. According to Figure 1, the total length of the studied route is about 75 km between Zargan and Farsiat and includes 155 cross sections, and the approximate length of the meander is 13.4 km. In order to simulate the hydraulic flow and sedimentation of the river by HEC-RAS model, geometric information (cross sections, distance of sections from the downstream control section, Manning's roughness coefficient and opening and narrowing coefficients), hydraulic information (flow information and water level level at the lower station) meteorological (water temperature) and sedimentary (related to flow-sediment discharge and bed sediments granularity) is necessary. In general, it can be said that after the formation of the loop, the upstream interval (R1) of its sedimentation decreases from upstream to downstream until it undergoes erosion at the bifurcation of the river, and the middle interval (R2) changes from erodible to sedimentary and the interval Downstream of the ring (R3) remains almost unchanged and shows very little tendency to erode. HEC-RAS model is used in this research. When using this software, the continuous flow series is divided into continuous flow segments based on flow and time variables. In general, it can be said that after creating the ring of the upstream interval (R1), its sedimentation decreases from upstream to downstream until it undergoes erosion at the bifurcation of the river, and the middle interval (R2) turns from erodible to sedimentary and the base ring interval (R3) remains almost unchanged and has a very little tendency to be erodible. The middle section of the Karun River (R2) turns from erodible to sedimentary with the creation of a loop, which is the reason for the tendency of the river to deposit sediments in this section after the creation of the loop, reducing the amount of incoming flow and, as a result, reducing the speed The flow in this section is caused by the division of the flow due to the two branches of the river upstream of this section.

reenhouse conditions, the use of biochar on yield and yield components of cucumber and to determine the effect of water stress and biochar on cucumber yield components in Birjand region. Application of biochar in soil increases the yield of cucumber (Cucumis sativus) of Storm cultivar and the combined effect of water stress and biochar modulates the effect of water stress on reducing crop yield.

Due to the conditions in the greenhouse and the type of cultivation (stacks), this study was selected as a factorial in a randomized complete block design with three dehydration treatments and four biochar treatments. Drought stress has three levels of 100, 75, 50% water requirement. And biochar levels of zero, 2, 4, 6 grams per kilogram of soil are selected The type of cultivation is in the form of a stack or a stack in which a stack is selected and divided into equal plots. Based on the number of treatments and replications selected, 36 plots are required, each plot being 80 cm long and 40 cm wide. After preparing a suitable culture medium, two seeds were planted in each plot with a distance of 2 cm because if the seed did not germinate or was destroyed, another one could be used as an alternative. Then, all plots were irrigated automatically until the plants became four-leafed, and pest control operations were carried out equally and equally among all plots.

The results show that biochar had a significant effect on cucumber height, cucumber diameter, cucumber weight, plant height, number of leaves and stem diameter at 1% level. It can be seen that water stress at the level of 1% had a significant effect on cucumber height, cucumber weight, number of leaves and stem diameter. But its effect on cucumber diameter index and plant height was not significant. In this experiment, the interaction effect of biochar and water stress at 1% level had a significant effect on cucumber height and cucumber weight and at 5% level on cucumber diameter and stem diameter, but its effect on plant height and number of leaves was not significant.

Drought stress was significant on cucumber height, cucumber weight, number of leaves and stem diameter at 1% level and had no effect on cucumber diameter and plant height indices. • The best performance in plant height, cucumber weight, number of leaves and stem diameter at I100 level. Consumption of 6 grams of biochar per kilogram of soil at the level of water stress, 100% water requirement had the highest yield on growth indices (cucumber height, cucumber weight) and at the level of 5% on stem diameter and cucumber diameter indices. The use of biochar on the indices of stem diameter, cucumber diameter, cucumber weight, cucumber height, number of leaves and plant height was positive and significant and the use of 6 g of biochar per kg of soil in all indicators has the highest yield for cucumber plant. The interaction effect of water stress and biochar was significant on cucumber height and cucumber weight indices at 1% level and on cucumber diameter and stem diameter indices at 5% level, but the interaction effect of stress and biochar on plant height and leaf area indices was not significant.