نشریه راهبردهای فنی در سامانه های آبی
پیاپی 3 (زمستان 1402)

Construction of bridge piers is expensive, and scouring near them can lead to instability. Without a suitable solution, it can ultimately result in the structure’s destruction. Therefore, a detailed study is required to understand this phenomenon and the factors affecting it. This research entails utilizing extensive field data to measure the local scour depth around bridge piers. It proposes an equation comprising scour-affecting parameters and defines an optimization model to establish this relationship. The decision variables of this model were determined using a meta-heuristic algorithm called the hybrid gray wolf-particle swarm (HPSGWO). For this purpose, various relationships were established to ascertain scour depth, and subsequently, the local scour depth of the bridge piers was calculated, based on these equations. Root Mean Square Error (RMSE), Relative Square Root (RSR), Nash-Sutcliffe Efficiency (NSE), Percent Bias (PBIAS), and Correlation Coefficient (CC) were employed as error measurement indices to evaluate the relationships. Upon comparison of the error measurement indices for the obtained relationships, the best input parameter combination and mathematical relationship for calculating scour depth were determined. These indices for the superior model are equal to 0.504 m, 0.52, 0.73, 7.7%, and 0.734 for RMSE, RSR, NSE, PBIAS, and CC, respectively. These values show that the equation presented in this research is suitable for calculating scour depth and is more reliable than the presented experimental methods. In the proposed relationship, scour depth is directly proportional to the Froude number and the ratio of base width to water depth while inversely proportional to the average size of bed particles to water depth.

The purpose of building surface water collection networks is to enhance the resilience of cities against unexpected events such as floods and to improve overall urban health. Recent rainfalls in Bandar Imam Khomeini have exposed vulnerabilities, leading to severe flooding in roads and streets due to the absence of canals and surface drainage systems. The problem has caused significant damage to the infrastructure of the region. The research aims to implement a runoff management system using the Geographic Information System in Bandar Imam Khomeini. For this purpose, digital layers of the area, including elevation, slope, direction of slope, and drainage network of the city were prepared using the Geographic Information System. The fuzzy logic method was then employed to identify areas with the potential for runoff accumulation in the region. The research findings indicate that these areas are concentrated in the east, center, northeast, and southeast of the region. Then, using the RiverTools technique and according to the map of the city's drainage network, the best routes for constructing proposed canals were determined. These canals include sub-canals, second-order main canals, and third-order main canals. The first-order canal is the main conduit that collects the water of the second and third order canals.

In recent years, Iran has grappled with escalating environmental crises, especially concerning water-related issues. This study aims to comprehensively understand the lived experiences of Isfahan citizens amid the city's water crisis. The methodology employed for this study was qualitative research, utilizing thematic analysis for data interpretation. A total of 27 Interviews were conducted with Isfahan citizens, focusing on their subjective experiences regarding the water crisis in the Zayande-Rood river. Data collection utilized a non-homogeneous sampling method. Predetermined criteria concerning credibility, reliability, and objec-tivity were applied to validate the findings. Data coding and theory-based analysis were performed simul-taneously during interviews. The data interpretation comprised basic, organizing, and inclusive coding stages. Analyzing the data revealed key categories, notably the impact on citizens’ quality of life under socio-environmental conditions, considered as an inclusive category. The subjective feeling of happiness derived from environmental conditions (the sense of citizens' happiness and satisfaction through the envi-ronment) and changes in the lifestyle of citizens were reconstructed as organizing categories. The main sub-organizing categories reconstructed in this study include changes in citizens’ lifestyle, alterations in leisure activities, social interactions, extending citizens' environmental concerns, Citizens' dissatisfaction with government performance, changes in sense of emotional well-being of citizens, Citizens' dissatisfaction with weather conditions, and decreasing satisfaction with Urbanization. Primarily, citizens consider drought and water shortage to be the main reasons for the reduced quality of (socio-environmental) lifestyle in Isfahan.

Planning the cultivation pattern and water rights allocation in the irrigated lands by the Khansar Sarcheshmeh springs requires knowledge of the discharge of the springs, estimated based on the Standard Precipitation Index (SPI) in this research. The relationship between the SPI index, precipitation, and discharges of Khansar Sarchesmeh springs has been evaluated over three different periods to estimate the groundwater resources and inflow to the streams. In a year with normal or near-normal climatic conditions and average annual rainfall between 295 to 494 mm, the average annual discharge of Sarcheshmeh springs is expected to be between 12.8 and 24.3 million cubic meters (average of 18.1 million cubic meters) with 67.5% probability and a frequency of 1.5 years based on the extreme value distribution. For a year with average dry climatic conditions (270 mm average annual rainfall), the predicted average annual discharge of Sarcheshmeh springs is 11.9 million cubic meters with a 9% probability and a frequency of 11 years. In extremely dry climatic years (with an occurrence frequency of 28 years), the discharge of Sarcheshmeh springs is expected to decrease to less than 10.1 million cubic meters per year. In normal and close to normal conditions, with average rainfall in the range of 236 to 326 mm in the first six months, the average annual (water year) discharge of Sarcheshmeh springs is expected to be 18.5 million cubic meters (ranging from 15.3 to 21.8 million cubic meters with a 67.5% probability based on the extreme value distribution). According to the results of this research, rainfall of less than 168 mm occurred in the first half of the water year is a warning of the occurrence of a moderate to extremely dry drought with an annual discharge of less than 11.6 million cubic meters that can be distributed in the streams. Precipitations of more than 394 mm during the first half of the water year also indicate the likelihood of a moderate to extremely wet year, with an annual rainfall of more than 28 million cubic meters. Results of the research indicate that less than 168 mm of rainfall in the first half of the water year signals the potential for a moderate to extremely dry drought, with an annual discharge of less than 11.6 million cubic meters that can be distributed in the streams, while more than 394 mm of precipitation during the same period suggests the possibility of a moderate to extremely wet year with an annual rainfall of more than 28 million cubic meters.

The comparative removal of lead (II) from water environments was investigated using Rhodococcus erythropolis in two modes of biosorption and bioaccumulation. The morphology of the biosorbent and its surface functional groups was investigated by SEM and FT-IR, respectively. Experiments were performed in discontinuous systems as a function of contact time, lead ion concentration, and biomass dose. Bioaccumulation by living bacterial cells and biosorption by inactive and non-living cells, were done. Biosorption was rapid, and equilibrium was reached in 15 min, while equilibrium in bioaccumulation was reached in 60 min. Initial metal concentration and amount of biomass significantly affected biosorption performance and contact time on bioaccumulation. The maximum biosorption efficiency using 0.1 g of inactive biomass after 15 minutes of contact time was 97.55%. Since metal recovery from inactive cell biomass is easier and can be performed with a higher absorption rate with a lower amount of biosorbent, the use of non-living biomass as a biological adsorbent is more efficient and significant.

The surge in population and imprudent consumption of water resources have created many challenges in securing sufficient water for sustaining human life. To supply part of the water demand for agriculture, the reuse of gray water is recommended. However, many decontamination methods are cost-prohibitive and pose challenges in sludge disposal after purification. The purpose of this research is to evaluate the feasibility of nitrate absorption by a mineral pumice adsorbent from nitrate solutions. The present study was conducted as a two-factor factorial experiment and complete randomized design with three replications. The study involved sampling mineral pumice with diameters of 1 cm, and 5 cm and gradation ranging from 1 to 5 cm over 45 days. The samples were calibrated by spectrophotometric method at a wavelength of 470 nm. Results showed that mineral pumice influenced nitrate absorption from the solution. The amount of nitrate in the control treatment was 0.88 grams per liter on the first day. The highest absorption occurred on the 20th day for the 1 cm soil gradation, resulting in a decrease to 0.62 grams per liter, which indicated 0.36 grams per liter of nitrate absorption. Larger gradations, however, showed the highest absorption on the 30th day. The 5 cm treatments and 1-5 cm gradation showed a reduction (absorption) of 0.19 and 0.27 grams per liter of nitrate, respectively, compared to the control treatment. According to the results, mineral pumice, an economical resource, can be used to absorb nitrate from nitrate solutions. Moreover, the used mineral pumice could find applications as a soil texture modifier or fertilizer in various fields beyond nitrate absorption.