Showing 387 results for Ec
V. Habibi Arbatani, M. Akbari, Z. Moghaddam, A.m. Bayat,
Volume 26, Issue 4 (12-2022)
Abstract
In recent years, indirect methods such as remote sensing and data mining have been used to estimate soil salinity. In this research, the electrical conductivity of 94 soil samples from 0 to 100 cm was measured using the Hypercube technique in the Saveh plain. 23 types of input data were used in the form of topographic and spectral categories. Land area parameters such as the Topographic Wetness Index (TWI), Terrain Classification Index (TCI), Stream Power Index (STP), Digital Elevation Model (DEM), and Length of Slope (LS) were considered as topographic inputs using Arc-GIS and SAGA software. Also, salinity spatial and vegetation indices were extracted from Landsat 8 images and were considered spectral inputs. The GMDH neural network was used to model salinity with a ratio of 70% for training and 30% for validation. The results showed that the soil salinity values were between 0.1 and 18 with mean and standard deviation of 5 and 4.7 dS/m, respectively. Also, the results of modeling indicated that the statistical parameters R2, MBE, and NRMSE in the training step were 0.80, 0.06, and 42.1%, respectively. The same values in the validation step were 0.79, 0.13, and 48.7%, respectively. Therefore, the application of spectral, topographic, and GMDH neural network indices for modeling soil salinity is effective.
H. Ghazvinian, H. Karami,
Volume 26, Issue 4 (12-2022)
Abstract
Runoff is formed by spending some time after rain and significantly depends on rainfall intensity, soil moisture, and slope. One of the fundamental questions about runoff is the time that it starts to create. In this research, the runoff start time in sandy loam soil was evaluated experimentally under different conditions using a precipitation simulator machine. The rainfall intensity parameters of (60, 80, and 100 millimeters per hour) and the slope of (0 and 5 percent) were investigated. The rainfall was created in the three soil treatment types completely dry (Sdry), the dry soil that had been saturated 24 hours before the test (S24hrlag), and the dry soil that had been saturated 48 hours before the test (S48hrlag). Eighteen tests were conducted on this soil. At the end of each test, the soil moisture was measured. The experimental results were compared with the numerical model of Green-Ampt. According to the Kendall and Spearman correlation test results, as the rainfall be intense, the start time of the runoff is lower. Also, the runoff starts at a faster time in the slope of 5 percent for every three types of soil. Also, the results of starting time of the runoff in the soil with a delay of 48 hours in the rain compared to the soil with a delay of 24 hours in the rain are closer in all of the rainfall intensity and slopes compared to the case of dry soil. Therefore, in the experiments related to a delay of 24 hours, the time of the start of runoff decreases. While in tests with a delay of 48 hours, it was not much different from completely dry soil. Also, the Green-Ampt results are close to the experimental results (R2=0.9775), and the maximum difference between the two mentioned methods is 4.8 minutes. Therefore, it can be used with the Green-Ampt method to calculate the start time of runoff in sandy loam soil in different states of rainfall intensity and bed slope.
A. Shahbaee Kotenaee, H. Asakereh,
Volume 27, Issue 1 (5-2023)
Abstract
Precipitation is one of the main elements of the Earth's hydro-climatic cycle and its variability depends on the complex and non-linear relationships between the climate system and environmental factors. Understanding these relationships and doing environmental planning based on them is difficult. Therefore, classifying data and dividing information into homogeneous and small categories can be helpful in this regard. In the present study, an attempt was made to prepare precipitation, altitude, slope, slope direction, and station density data for 3423 synoptic, climatological, and gauge stations in Iran in the 1961-2015 years’ period. These data were entered into fuzzy (FCM), self-organizing map neural network (SOM-ANN) models and precipitation-spatial zoning. The outputs of the two models were compared in terms of accuracy and efficiency. The results obtained from the output of the models have divided the rainfall conditions of Iran into four zones concerning environmental factors. Evaluations also showed that both models had high accuracy in classifying precipitation parameters; However, the fuzzy model has a relative advantage over the neural network model in the accuracy of results.
H. Siasar, A. Salari,
Volume 27, Issue 1 (5-2023)
Abstract
Access to large precipitation data with appropriate accuracy can play an effective role in irrigation planning and water resources management. Satellite images generate high, wide, cheap, and up-to-date data is a good way to estimate precipitation. In this research, the Google Earth engine system and precipitation products from satellite images of PERSIANN and CHIRPS models in daily, monthly, and annual time intervals were used to evaluate and validate the amount of precipitation in Bandar Abbas station during the statistical period of 1983-2020. The results showed that the precipitation estimation by PERSIANN and CHIRPS satellites on a monthly and annual scale is more accurate than the daily scale. The highest correlation coefficient and the least RMSE belonged to the PERSIANN algorithm on monthly and annual scales. The value of the correlation coefficient in the PERSIANN algorithm on daily, monthly, and annual scales is equal to 0.32, 0.83, and 0.94, respectively. The correlation coefficient in the CHIRPS algorithm in daily, monthly, and annual scales is equal to 0.24, 0.71, and 0.90, respectively. The coefficient of determination (R2) of PERSIANN and Chrips algorithms on a monthly scale were 0.89 and 0.70, respectively, and for an annual scale were 0.88 and 0.80, respectively. The general conclusion of this study indicated that the accuracy of the two algorithms in determining the spatial pattern of rainfall on a monthly and annual scale is appropriate, and the PERSIANN algorithm had a higher accuracy on a monthly time scale.
M. Ahmadi, H. Ramezani Etedali, A. Kaviai, A.r. Tavakkoli,
Volume 27, Issue 1 (5-2023)
Abstract
Studying the effects of drought in mountainous areas is facing problems due to the inappropriate distribution of stations, the lack of long-term data, and areas lacking statistics. Therefore, the main objective of this research was to investigate the drought indices of Kurdistan province using TRMM satellite data and ECMWF dataset, as well as to evaluate their accuracy against the data of land stations in Kurdistan province. First, ECMWF precipitation data for the 2000-2020 period and TRMM precipitation data for the 2000-2019 period were obtained and evaluated using RMSE, MBE, and correlation coefficient statistics. Spearman's correlation coefficient showed a significant relationship between the TRMM satellite precipitation data and the ECMWF dataset with ground stations at the 5% level, and the value of this coefficient was between 0.95-0.85. According to the results, it can be acknowledged that the TRMM satellite rainfall and ECMWF dataset in the monthly time scale had proper accuracy at the Kurdistan province level. Therefore, these two sources were used to examine the drought indices. SPI, SPEI, and ZSI drought indices were calculated in different monthly periods (1-48), PNI in different monthly, seasonal, and annual periods in Kurdistan province (Saqqez, Qorveh, Bijar, Sanandaj stations). Spearman's correlation coefficient indicated a significant relationship at the 5% level between the SPI, ZSI, PNI, and SPEI index of the ECMWF dataset with ground stations. The results of the SPI index showed that the lowest RMSE value for the TRMM satellite at the Saqqez station and the three months was equal to 0.45, and for the ECMWF dataset at the Sanandaj station and the 24 months was equal to 0.35.
S. Salehi, A. Mahmoodi Moghadam,
Volume 27, Issue 2 (9-2023)
Abstract
The present study investigated the related parameters to decrease the seepage through homogenous and heterogeneous earth dams by employing experimental models and solutions. Two heterogeneous earth dam models with vertical clay cores were considered to illustrate the effect of the electrokinetic application on the time failure factor. The seepage lines were measured along the longitudinal section from the heel to the toe using the observation wells by adjusting the electrodes of the electrokinetic application through the vertical clay core. The initial comparison expounds that adjusting the electrokinetic approach can decrease the level of the seepage line due to depleting water by considering horizontal drainage. Furthermore, the failure time was increased by 18 percent due to inputting the voltage in the clay content. The results indicated that the models with an electrokinetic approach were stabilized more than the ones. The hydrographs of the flow discharge were measured along the experimental tests to investigate the effect of electrokinetics with and without electrodes in 10 and 20 clay percent of the dam soil content. Results indicated that employing the electrokinetic application due to increasing clay content caused the effect of the electrokinetic was significantly increased and it caused the discharge flow reduced of 32 percent.
A.r. Eftekhari, M. Mirmohammad Sadeghi, A. Jalalian,
Volume 27, Issue 2 (9-2023)
Abstract
The use of biotechnology-based methods in the field of geotechnical engineering has led to the birth of new knowledge of biogeotechnology and several studies have been conducted using this new knowledge in various geotechnical issues including reducing permeability and increasing shear strength, especially in sandy soils and the desired results have been obtained. Nevertheless, little research has been done using biogeotechnology in the field of improving the mechanical properties of clay soils, especially in reducing the swelling of expansive soils, which is considered one of the types of problematic soils. The main cause of swelling of expansive soils is the presence of montmorillonite clays in these types of soils. Using chemical additives to stabilize expansive soils such as lime and cement is a common practice. However, environmental concerns related to greenhouse gas production caused by the production of chemical substances and the destructive effects of these substances on the environment and soils have encouraged researchers to use other sustainable stabilization alternatives. Microbial Induced Carbonate Precipitation (MICP) is a technique that can be a promising solution to solve this problem. The objective of the present study was to investigate the effect of the MICP method on the swelling of expansive clay soils and its effect on the mechanical strength of this type of soil. One-dimensional swelling tests, uniaxial compressive strength tests, and Atterberg limits tests were performed on clay soil with a liquid limit of 53 using Sporosarcina pasteurii bacteria, calcium chloride, and urea as nutrients. Taguchi's method was used for the design of the experiments and the statistical analysis of the results. This method designs experiments through partial factorial and reduces their number without a significant effect on the results. Bacterial concentration, nutrient molarity ratio, treatment time, and soil moisture were selected as four factors with Four levels of variation. The results showed that the (MICP) method was effective in reducing the swelling potential of expansive soils and also caused a significant increase in the unconfined compressive strength of the soil and its undrained shear strength.
V. Moradinasab, S. Hojati, A. Landi, A. Faz Cano,
Volume 27, Issue 2 (9-2023)
Abstract
Parent material and topography are among the soil-forming factors that affect soil evolution by influencing different parameters. This study was conducted to compare the effect of marl and calcareous parent materials in different slope positions, including the summit, shoulder, foot-, and toe-slopes on soil clay mineralogy in the Karoon 3 Basin, east of Khuzestan Province. Four soil profiles in each of the two topo-sequences were dug. They were sampled based on their genetic horizons and some physical, chemical properties, and clay mineralogy were measured. The results showed that the type and abundance of clay minerals identified for both parent materials were more affected by topo-sequence position. The composition of minerals identified in the topo-sequence with marl parent materials included kaolinite, palygorskite, smectite, chlorite, mica, and quartz, and in the topo-sequence with calcareous parent materials, palygorskite, smectite, chlorite, mica minerals, and quartz, and most of the identified minerals were also observed in all positions in the C horizon. However, in marl parent materials kaolinite, and calcareous parent materials, smectite seems to have been formed pedogenically. The result of the association between Weaver and Beck indicated that most of the clay minerals are in the equilibrium of Palygorskite.
A. Nasseri,
Volume 27, Issue 2 (9-2023)
Abstract
The selection of precision value for Roughness coefficient (RC) is necessary to design and utilize earth canals due to the vast distribution of Echinocola crus-galli in earth canals. Therefore, the current study was conducted to evaluate roughness coefficients in earth canals with Echinocola crus-galli at the Moghan plain (in the North-west of Iran). In the network of Moghan, 42 canal sections were selected to measure vegetation density and wet weight, water flow velocity (with a flow meter), and canal cross sections (with profilimetery devices). The hydraulic characteristics were estimated after water depth measurements. The Manning roughness coefficient (n) was applied to estimate the roughness coefficient. Path analysis was applied to identify the factors affecting the roughness coefficient. Multivariate cluster analysis using Ward's method and squared Euclidean distance was applied to cluster factors affecting the roughness coefficient in canals. The results revealed that RC averaged 0.015. The path analysis showed that the wetted perimeter, crop biomass, flow cross-sectional area, flow velocity, and hydraulic radius had the highest total effect on the roughness coefficient, respectively. The factors clustering showed that two clusters were obtained in the Euclidean distance of 11. The first cluster included flow velocity, crop biomass, flow rate, and bed slope; and the second cluster included flow cross-sectional area, wetted perimeter, and hydraulic radius. The findings could be helpful for designing and operating canals in the studied or similar regions.
A. Shahnazari, S. Sadeghi,
Volume 27, Issue 2 (9-2023)
Abstract
In the present paper, crop pattern criteria have been evaluated relying on sustainable development to increase agricultural water productivity. Seven criteria were selected as the main environmental and economic criteria and were prioritized and reviewed for important and strategic products in the Tajan catchment of Mazandaran province. Criteria prioritization was done using optimization through a genetic algorithm with an objective function based on sustainable development. Then, physical and economic productivity indices were calculated to determine the productivity value. Based on the results, in the selection of the crop pattern, firstly, the category of economic criteria and finally the category of environmental criteria have been given attention to the farmers in the current situation. But in the genetic optimization algorithm, all priorities have a similar order from the environmental point of view and then from the economic point of view although each product has its order of criteria. By this prioritization, the parameters of the cultivated area, the volume of water consumed, and the amount of chemical fertilizers have decreased on average by 26%, 34%, and 21%, respectively, and the parameters of product performance and profitability have increased by 43% and 61%, respectively. In addition to providing environmental standards and increasing sustainable development, this prioritization causes an average increase in physical productivity by 84% and an increase in economic productivity by 72%.
H. Asakereh, A. Shahbaee Kotenaee,
Volume 27, Issue 2 (9-2023)
Abstract
Identifying the behavior of precipitation is one of the most important planning principles related to water resources. In this research, an attempt was made to analyze the trend of time changes in extreme rainfall profiles of the country by using the daily rainfall data of 3423 synoptic, climatology, and rain gauge stations for the period from 1970 to 2016 and by performing interpolation using the kriging method. Then, using percentile profiles (percentile less than 10, less than 25, 25 to 75, 75 to 90, and above 90) and regression analysis, changes in the frequency of member days of each of the percentile methods over time were calculated and mapped. The results showed that during the studied period, 86.6% of cells associated with days with the tenth percentile or less in the country had an increasing trend. On the other hand, the pixels associated with days with the 90th percentile and more have shown an increasing trend. Considering that the pixels with the 25th, 25th-75th percentiles (normal), and 75th percentile have shown a decreasing trend in terms of the number of days in their group, it can be concluded that the country's rainfall conditions and the days with rainfall are towards the limit values has moved and the possibility of drought or destructive floods has increased in the country.
E. Mirzakhani, H.r. Motaghian, A.r. Hosseinpur,
Volume 27, Issue 3 (12-2023)
Abstract
In addition to the distribution of elements in the soil solid phase, element species in the solution are also very important due to their importance of providing elements for root uptake. For a deeper study of the chemical cycle of elements in saline soils treated with biochar, the study of speciation is very useful and provides a method to reduce or transform the toxicity caused by toxic elements in saline soils. Therefore, to investigate the effect of biochar on Cd speciation in two saline calcareous soils, 15 mg kg-1 Cd as cadmium chloride was added to the soil sample (200 g), and the soils were incubated for three weeks at 25±2 °C at 80% field capacity. After the incubation period, salinity levels of 20 and 40 mmol kg-1 as sodium chloride (equal to 3.65 and 7.30 dS m-1) were added to the soils. Then, the 1% (w/w) of the sugarcane bagasse and biochars produced at 400 and 600 °C were added to the soils, and then incubated for three months at 25±2 °C at 80% field capacity. At the end of the incubation period, for the speciation of Cd in the soil solution (in a 1 to 2 ratio), the concentration of dissolved cations and anions in the soil samples was measured. The results showed that the interaction between salinity, biochar, and soil on Cd2+, CdCl+, CdCl20, and Cd(SO4)22- was significant. The application of biochar in sandy soil reduced (p <0.05) the concentration of CdCl+, CdCl20, CdSO40, and CdOH+ species compared to the control soil, while it did not affect clay soil. Also, salinity caused by sodium chloride in sandy soil increased the concentration of CdCl+ and CdCl20 species and decreased CdSO40 and CdOH+ species compared to the control soil (p <0.05). The results showed that biochar in saline sandy soil was more effective than clay soil in reducing Cd toxicity.
V. Rahdari, A.r. Soffianian, S. Pormanafi, S. Maleki,
Volume 27, Issue 3 (12-2023)
Abstract
Industrial development is necessary to create employment and achieve welfare. Nevertheless, due to the important environmental effects of these uses, it is necessary to consider the environmental issues in industrial area land allocation. The current research used the multi-criteria evaluation method and the combination with fuzzy concepts to investigate the land capability for industrial development in the Plasjan sub-basin in the Zayandeh-rood river basin. Evaluation criteria were determined by literature reviewing and using experts' knowledge, and standard applying fuzzy method via proportional functions and weighted using the hierarchical method. The combined classification of satellite images prepared the land use and land cover map. Then, the standardized criteria were combined in the form of a weighted linear combination and the industrial development capability model was prepared for this area and classified into five land capability classes. The results showed that environmental considerations have the most weight with 0.23, and geological and soil texture criteria have the least weight with 0.06. According to the results, only 213 hectares of the region were allocated for industrial and mining use at the time of the study. In comparison, 2325 hectares of the region have very high industrial potential which shows the capability for increasing industrial areas. Also, the highest class of land capability was related to areas without the capability for industrial development with an area of 246375 ha, equivalent to 60% of the entire region, which shows the importance of conservation of the important functions of this region in water supply and ecological resources.
M. Majedi Asl, T. Omidpour Alavian, M. Kouhdaragh, V. Shamsi,
Volume 27, Issue 3 (12-2023)
Abstract
Non-linear weirs meanwhile economic advantages, have more passing flow capacity than linear weirs. These weirs have higher discharge efficiency with less free height upstream compared to linear weirs by increasing the length of the crown at a certain width. Intelligent algorithms have found a valuable place among researchers due to their great ability to discover complex and hidden relationships between effective independent parameters and dependent parameters, as well as saving money and time. In this research, the performance of support vector machine (SVM) and gene expression programming algorithm (GEP) in predicting the discharge coefficient of arched non-linear weirs was investigated using 243 laboratory data series for the first scenario and 247 laboratory data series for the second scenario. The geometric and hydraulic parameters were used in this research including the water load (HT), weir height (P), total water load ratio (HT/p), arc cycle angle (Ɵ), cycle wall angle (α), and discharge coefficient (Cd). The results of artificial intelligence showed that the combination of parameters (Cd, H_T/p, α, Ɵ) respectively in GEP and SVM algorithms in the training phase related to the first scenario (Labyrinth weir with cycle wall angle 6 degrees) were respectively equal to (R2=0.9811), (RMSE=0.02120), (DC=0.9807), and (R2=0.9896), (RMSE=0.0189), (DC=0.9871) in the second scenario (Labyrinth weir with a cycle wall angle of 12 degrees) it was equal to (R2=0.9770), (RMSE=0.0193), (RMSE=0.9768), and (R2 = 0.9908), (RMSE = 0.0128), (DC = 0.9905), which compared to other combinations has led to the most optimal output that shows the very favorable accuracy of both algorithms in predicting the coefficient the Weir discharge is arched non-linear. The results of the sensitivity analysis indicated that the effective parameter in determining the discharge coefficient of the arched non-linear Weir in GEP and in SVM is the total water load ratio parameter (HT/p). Comparing the results of this research with other researchers revealed that the evaluation indices for GEP and SVM algorithms of this research had better estimates than other researchers.
S. Najmi, M. Navabian, M. Esmaeili Varaki,
Volume 27, Issue 3 (12-2023)
Abstract
The increasing need for water resources and controlling the discharge of wastewater into the environment shows the necessity of wastewater treatment. Green methods such as constructed wetlands and phytoremediation use biological processes in the environment for wastewater treatment. Considering the effect of cultivated constructed wetland performance from wastewater quality and climatic factors, the objective of this study was to evaluate the performance of hybrid and subsurface vertical and horizontal wetlands to improve the biological and chemical oxygen demand of the wastewater treatment plant in Rasht City. The effect of Phragmites australis and Typha latifolia plants on the treatment performance was investigated. Wastewater retention time in wetlands varies from monthly in winter and weekly in spring and summer. The results showed that the performance of wetlands in reducing biological oxygen demand (BOD) was more than chemical oxygen demand (COD). Plants improved the performance of the wetland by more than 50%, but no significant difference was observed between the performances of the two plants. The arrangement of the plant's cultivation was not effective in the amount of biological and chemical oxygen removal. The hybrid wetland was able to improve the wastewater quality twice as much as the vertical wetland. Comparing the concentration of the effluents from the wetlands with the standards showed that the effluents from the hybrid wetlands could only be used for agricultural consumption.
R. Samadi, Y. Dinpashoh, A. Fakheri-Fard,
Volume 27, Issue 3 (12-2023)
Abstract
A hydrological parameter affecting the management of water resource systems is changes in the amount and occurrence time of extreme precipitation (OTEP). In this research, the seasonality of precipitation in the Lake Urmia (LU) basin was analyzed using the daily extreme precipitation data of 30 rain gauges in the statistical period of 1991-2018. The uniformity of OTEP was tested by Rayleigh and Kuiper’s tests at 0.1, 0.05, and 0.01 levels. The slope of the trend line for OTEP was estimated using the modified Sen slope estimator. The uniformity of OTEP was rejected at each level. The results revealed two strong seasons: late winter and early spring (S1) and autumn (S2) for OTEP. The results showed a general median seasonality index of 0.3, which changed to 0.82 and 0.9 for S1 and S2, respectively, after dividing the whole year into two seasons. The seasonal strength of S1 was similar in both the western and eastern parts of LU, but the west of the lake was stronger than the eastern part in S2. In S1, negative and positive trends in the OTEP were observed on average in 40% and 60% of the stations, respectively, with corresponding values of 77% and 27% for S2, respectively.
M. Naderi, V. Sheikh, A. Bahrehmand, C.b. Komaki, A. Ghangermeh,
Volume 27, Issue 4 (12-2023)
Abstract
Greenhouse gases and the occurrence of climate change have occurred with the development of technology and the industrialization of human societies. long-term forecasting of climate parameters has always been interesting due to the importance of climate change for the earth and its inhabitants. General Circulation Models (GCMs) are one of the most widely used methods for evaluating future climate conditions. In the present study, the results of three general circulation models including the American model of GFDL-CM3, the Canadian model of CanESM2, and the Russian model of inmcm4ncml for the study area were evaluated and the CanESM2 model was selected as the superior model. The RCP scenarios 2.6, 4.5, and RCP 8.5 were used with the CanESM2 model to assess climate change conditions across the Hablehroud River basin for the period 2020-2051. According to the results, the total monthly precipitation shows an increasing trend in the coming decades 2020-2051 period compared to the period 1986-2017. The results of the study of temperature changes in the period 2020-2051 in the Hablehroud River basin also indicate an increase in the monthly average of maximum and minimum temperatures in the coming decades. The consequences of these conditions are of great hydrological importance in the study area, this condition necessitates the adoption of climate change adaptation policies in this watershed.
A. Salar, M. Shahriari, V. Rahdari, S. Maleki,
Volume 28, Issue 2 (8-2024)
Abstract
Unbalanced development of different land use/cover in basins without considering the contribution of all components, can cause serious damage to the stability of the entire basin. The development of agricultural areas by increasing the amount of water use and creating dams upstream of rivers are the most important threats to wetlands in many places. Jazmorian wetland is one of the seasonal wetlands in the south-east of Iran. The most important source of water supply for this wetland is the Halil-Rood River. To investigate the land use/cover changes of Jazmurian wetland and
Halil-Rood River, the time series of Landsat satellite data for the years 1354, 1374, 1387, and 1401 were used in the present research. The Landsat satellite images were classified using a hybrid classification method and the land use/cover of the study area maps were prepared. The accuracy of the prepared maps for the latest image was calculated by preparing the error matrix, calculating the kappa index, and the overall accuracy of more than 0.8 and 9%, respectively. The investigation of the prepared maps showed that the area of land under water increased from 1354 to 1374 and then decreased from 119,552 hectares in 1374 to 723 hectares in 1401. The area of agricultural land increased from 2131 hectares in 1354 to 133913 hectares in 1387 and declined to 105795 hectares in 1401. The results of this study show that in this period, with the construction of a dam upstream of the Halil-Rood River, and the development of agricultural lands, the water volume level of the wetland decreased, and the wetland completely dried up in 1401. The present study indicates the necessity of considering different components of a watershed in development planning to achieve sustainable development.
M. Khajeh, C. B. Komaki, M. Rezaei, V. Sheikh, L. Ebadi,
Volume 28, Issue 2 (8-2024)
Abstract
In the future, the risk of land subsidence due to water resources shortage crisis and improper water resources management will become more and more dangerous. It is necessary to assess and identify areas susceptible to subsidence risk and take necessary actions to reduce risks related to land subsidence. In this study, first, the risk of land subsidence was identified and evaluated using a radar interferometry method called LiCSBAS. Then, the spatial relationship between the occurrence of land subsidence hazard and effective factors such as ground elevation, slope, slope aspect, lithology, land use, groundwater decline, distance from rivers, distance from faults, topographic moisture index, and arc curvature was investigated using the random forest (RF) model. In the end, the land subsidence hazard sensitivity map was prepared after calibrating the random forest algorithm. The analysis of LiCSBAS interferometric time series data from 2015 to 2022 showed that the center of the Marvdasht-Kharameh plain and adjacent agricultural areas are continuously subsiding and the mean deformation rate map showed a subsidence rate of 11.6 centimeters per year. The results of determining the spatial relationship between subsidence occurrence and effective factors confirmed the positive impact of distance from rivers, urban and agricultural land uses, depth of bedrock (aquifer thickness), groundwater decline, and alluvial and fine-grained formations on this phenomenon. Also, the results of subsidence modeling using the random forest algorithm showed that factors such as bedrock depth, groundwater decline, land use, and geology have the greatest impact on the potential for subsidence occurrence in the study area. Also, based on the results, about 3 to 4 percent of the areas are in the very high and extremely high-risk classes of land subsidence, especially in the center and suburbs of Mervdasht. Therefore, water resources management and control and developing a systematic program to reduce subsidence risk and aquifer recharge conservation in Merudasht-Kharameh Plain is essential.
M.j. Aghasi, S.a.r. Mousavi, M. Tarkesh, S. Soltani,
Volume 28, Issue 3 (10-2024)
Abstract
Astragalus is the vegetation of many mountains of Iran's plateau and plays a major role in providing ecosystem services due to its pillow shape and deep rooting system, they facilitate the control and penetration of precipitation into the soil. The correlation of Astragalus ecosystems with arid and semi-arid climates has made them vulnerable to climate change. In this study, a runoff yield map based on the Budyco curve under current and future conditions of climate change (2050) was prepared using climate and temperature data from the Chelsea site (CanESM2 GCM) in TerrSet software and by using maps of sub-watersheds, annual precipitation, annual potential evapotranspiration, soil depth, plant accessible water and the current and future "Land Cover - Land Use" map, with a combination of field methods and species distribution models at the local scale of the Shur River watershed of Dehaghan (Central Zagros). Finally, the excess runoff damage produced due to climate change was estimated using the replacement cost method. The results indicated an increase in the annual runoff volume of the watershed from 70 million cubic meters to 105 million cubic meters under climate change conditions for the RCP26 scenario in 2050. Taking into account the cost of 10 million Rials for controlling 530 cubic meters of runoff through various watershed management projects, preventing the damages of excess runoff produced requires a credit amounting to 660 billion Rials based on the present value. This study proved the ability of TerrSet software to predict and produce an ecosystem service map of runoff yield under climate changes or land use changes and with the purpose of valuation on a local scale. Also, the above valuation can be the basis for planning and providing credit for the study and implementation of watershed management projects to deal with the threats of climate change.
