Search

Climate change and its side effects on weather variables and water resources is one of the recent international concerns. This research aims to project future changes in weather variables due to climate change for different emission scenarios of RCP2.6, RCP4.5 and RCP8.5 to assess and compare climate change impact on river flow variation based on hybrid application of deep learning and LARS-WG6 in different climates of Iran (CSA: cold semi-arid; HT: humid temperate; CA: cold arid). For this purpose, best combination of daily rainfall and discharges data with different lags were selected as inputs in rainfall-runoff modeling using Convolutional Neural Networks (CNN) model. Predicted meteorological data by the LARS-WG6 in the future (2021-2040) were then used as inputs for the selected CNN model and consequently runoff was predicted. Obtained findings showed that projected rainfall changes in 2021-2040 compared to the base period in scenarios of RCP2.6, 4.5 and 8.5 will be +14, +11, +6% in CA, +8, +1, +2% in CSA and +3.7, -1, -2.6% in HT regions, respectively. Whereas, maximum discharge in CA climate in scenario RCP2.6 is projected to raise about 18%, in the HT climate shows a reduce of about 5% in RCP8.5 and in CSA will decrease by about 5% in RCP2.6. Considering the effect of climate as well as seasonal changes in each region on the amount and direction of the climate change impacts on meteorological and hydrologic variables changes, assessing climate change impact in each region is necessary to extract adaptation strategies in water resources management. [ABSTRACT FROM AUTHOR]

Floodplains are really important for the environment as they provide various functions for waterways, including ecological, hydrological, and geomorphic ones. During overbank flows, there are complex hydrodynamic conditions that occur as water interacts with the rough floodplain vegetation and drag forces due to the vegetation that changes the flow pattern. However, we still don't fully understand how floodplain vegetation influences channel-altering hydrodynamic forces and sediment transport. To address this, we conducted flume experiments and measured flow pattern and sediment transport under varied floodplain geometry and rigid and flexible conditions. For this purpose, a physical model was constructed in the laboratory, in which plastic rods with a diameter of 10 mm will be used as trees, and artificial grass will be grass vegetation. Thus, 36 experiments were conducted in which the sedimentation and hydraulic parameters of the flow were calculated by measuring the flow velocity, water surface, and sediment transport rate. The results show that in the floodplain with dense (rigid and flexible) vegetation, the friction coefficient (f) is even 1.5 times higher than in the floodplain without vegetation. The parameters such as flow velocity, bed shear stress and Darcy Weissbach friction coefficient increase in the vertical plane between the main channel and floodplains due to the difference in roughness between the main channel and floodplains. In addition, in the main channel, the flow resistance is almost constant and does not depend on the vegetation density. The Darcy-Weissbach friction coefficient is greatly increased in the presence of grass and tree vegetation on the floodplain, and the larger contribution of f is due to the grass vegetation. The results also showed the sediment transport rate has a direct relationship with the angle of divergence and density of vegetation and an inverse relationship with the relative depth of the flow. Therefore, as the sediment transport rate decreases in the diverging compound channel, the wavelength and height of the dunes increase. At smaller divergence angles, the dunes tend to the top of the zero line (the level of the sediments before the formation of the bed form). In the presence of vegetation, due to the increase in the roughness ratio of the floodplain to the main channel, the contribution of the main channel to the flow rate increases. As a result, the sediment transport rate increases. • The effect of rigid and flexible vegetation of floodplains on the flow pattern and transport of sediments was investigated. • The friction coefficient was 1.5 times higher than in the floodplain without vegetation in divergent compound channels. • In the main channel, the flow resistance is almost constant and does not depend on the vegetation density. • The sediment transport rate has a direct relationship with the angle of divergence and density of vegetation. [ABSTRACT FROM AUTHOR]

This study aims to provide insights into groundwater stress and subsidence in the Varamin plains, located in central Iran. To achieve this, groundwater distributed modeling was simulated, and the groundwater stress index was evaluated accordingly. The area was divided into nine sections based on the intensity and spatial distribution of stresses and subsidence. The study conducted sensitivity analysis to reduce uncertainty, focusing on the importance of abstraction, recharge, and environmental flow at groundwater footprint and stress index equation. The impact of input variables on the groundwater stress index was evaluated using two methods of local and global sensitivity analysis, and the results were compared. A partial correlation criterion was also applied to measure the relationship between stress-dependent variables and three independent variables. The analysis revealed that the correlation analysis and global sensitivity analysis are consistent with each other and differ from the local sensitivity analysis. The abstraction based on global sensitivity analysis and correlation analysis has the greatest impact on stress, while a local sensitivity analysis showed that the reduction in recharge had the greatest effect. The study found that the impact of environmental flow requirements is negligible. Based on the results, the study presented different scenarios for reducing stresses in critical areas and proposed corresponding scenarios to reduce stress in the future management of the plain. A review of three different scenarios for the Varamin plain revealed that recharge is the most effective parameter that correlates with local sensitivity analysis. However, based on the results of the analysis of global sensitivity and correlation coefficient analysis, abstraction has the highest effectiveness. • The effect of recharge, abstraction and environmental flow was studied on GWSI. • Sensitivity analysis and management scenarios have been performed in this research. • Global sensitivity analysis indicates abstraction is the most effective variable. • Recharge has the greatest effect on GWSI based on local sensitivity analysis. • The artificial recharge is more effective to reduce stress in the aquifer. [ABSTRACT FROM AUTHOR]

Abstract: A 2×3 factorial experiment was conducted to evaluate the effect of partial substitution of dietary fish meal with soybean meal and citric acid (CA) supplementation on growth, food utilization, muscle composition and nutrient digestibility of Beluga, Huso huso. Three isonitrogenic and isoenergetic diets, as SBM1 (soybean meal protein (SBP):fishmeal protein (FP)=1:3), SBM2 (SBP:FP=2:3) and SBM3 (SBP:FP=1:1) containing two levels of CA (0 and 30gkg−1) were fed to triplicate groups of fish for 8 weeks. The results revealed that adding CA increased (P<0.05) the weight gain (WG), specific growth rate (SGR) and protein efficiency ratio (PER) and decreased (P<0.05) food conversion rate (FCR) whereas partial substitution of fishmeal with soybean meal decreased (P<0.05) growth performance. Partial replacement of fishmeal with SBM (P=0.021) as well as CA supplementation (P=0.019) and their interaction (P<0.001) affected hepatosomatic index (HSI). No differences (P>0.05) were observed for viscerosomatic index (VSI) among treatments (P>0.05). No differences (P>0.05) were detected in moisture, protein of muscle sample among treatments, but lipid content was reduced (P<0.05) while ash content increased (P=0.035) by CA. Soybean meal decreased (P<0.05) nutrient digestibility, whereas CA improved apparent protein and phosphorus (P) digestibility (P=0.011 and P<0.001 respectively). No interaction (P<0.05) between levels of SBM and CA was found on these parameters. Results of the present study indicate that Beluga has a limited ability to utilize SBM as a protein source in practical diets whereas CA can improve growth and nutrient utilization in Beluga. [Copyright &y& Elsevier]

The need for potable and agricultural water will increase in the future due to both population growth and climate change. Therefore, the optimal operation of systems reflecting these issues will be more essential than ever. This study was conducted to develop a quantitative-qualitative model for optimal operation of dams considering the effects of climate change on reservoirs' inflow and downstream demands. The statistical downscaling model was used for long-term simulation of precipitation and temperature to account for the effects of climate change in the future. An optimal operation model based on simulated future runoff and water demands was developed. To investigate the climate change impacts on reservoir operation, reliability, vulnerability, and resiliency indices were calculated in the base period and for future periods. The results show an increase in the mean temperature and a reduction in the mean annual precipitation in future years compared to those in the current observation period. Based on the proposed optimization model, the total dissolved solids of the supplied water have been decreased. The reservoir performance also exhibited a significant quantitative improvement when compared to the standard operating policy. [ABSTRACT FROM AUTHOR]

• The epistemic uncertainty is considered for time-dependent fuzzy reliability analysis of corroded RC beam. • Fuzzy time-dependent reliability index is obtained using α -cut approach. • The optimization method of hybrid HGAPSO is proposed to search the bounds of reliability index. • Three-term conjugate method is used for computing the reliability index of RC beams under corrosion. Evaluation of reinforced concrete (RC) structures which are subjected to the damaging environmental factors during the service life is critical. The service life model, the effects of environmental factors with their extent of damage during the service period of the structure could be predicted. Various uncertainties that came with this assessment confidence in the results should be taken by a safe margin. Structural reliability methods are one of the best tools to calculate the life model that considers the random properties of parameters. However, if the epistemic and inherent uncertainty of parameters with their time-dependent changes considered, the life model is more reliable. The reinforcement corrosion is the most damaging mechanism that causes the premature degradation of RC structures and substantial economic losses each year. In this work, the time-dependent reliability of an RC beam with chloride-induced corrosion considering epistemic uncertainty via an efficient numerical procedure is developed. Fuzzy time-dependent reliability index has been calculated using α -cut approach based on a hybrid version of genetic algorithm (GA) and particle swarm optimization (PSO), namely HGAPSO applying three-term conjugate reliability method. Results showed that the proposed numerical approach could efficiently and robustly estimate the fuzzy time-dependent reliability index. [ABSTRACT FROM AUTHOR]

In this study, performance of an in-stream hydro-kinetic turbine and its impacts on a simplified river channel (known as a compound open-channel) flow has been numerically examined. To this end, a steady Reynolds-Averaged Navier-Stokes solver has been employed together with the moving reference method to simulate the turbine rotation as well as the Reynolds Stress Model (RSM) as the turbulence closure. The results showed that the presence of a hydro-kinetic turbine causes dramatic changes in the natural flow structure of the compound channel, which varies depending on the location of turbine installation. Comparison of turbine installation in various locations in the cross-section of the channel showed that minimum effects on the natural flow conditions have been occurred in the installation at the main-channel being far from the bed. It has also been observed that the bed shear stress remains virtually constant for different hydro-kinetic turbine locations. Values of the power coefficient indicate that the highest value of maximum power coefficient is obtained where the hydro-kinetic turbine is installed at the interaction zone of the compound open-channel. This observation implies that cellular secondary currents of the compound channel have positive effects on the turbine power. Finally, it is noted that the thrust coefficient variation with the installation location is insignificant compared to the variation of this coefficient with respect to the inlet velocity and the ratio of the blade flow speed to the flow speed. • Performance and impacts of an in-stream hydro-kinetic turbine on a compound open-channel flow have explored. • Turbine makes changes on the flow structure of compound channel which varies respect to the location of installation. • Minimal effects on the natural flow condition have been observed in the main channel far from the bed installation. • Maximum turbine power has been obtained as turbine installed in the interaction zone of compound open-channel. [ABSTRACT FROM AUTHOR]