نشریه مهندسی اکوسیستم بیابان
پیاپی 37 (زمستان 1401)

As a major type of atmospheric and environmental pollutant, dust bears terribly harmful consequences for agriculture, industry, and human health. In this regard, identifying the potential sources of dust is the main required step in managing and controlling the dust phenomenon and reducing its risks, especially in arid and semi-arid environments. Therefore, this study used the modern maximum entropy algorithm to predict the potential sources of dust in eastern Iran by considering the effective environmental factors.

As for the modeling process, eight effective factors in dust generation, including land slope, landform, vegetation, precipitation, wind speed, lithology, land use, and maximum air temperature were analyzed as independent variables involved in the occurrence of dust storms. Moreover, petrologic, land use, pedologic, precipitation, vegetation, and slope maps were prepared. On the other hand, the locations identified by Iran’s Geological Survey as the sources of dust were used as dependent variables. Furthermore, the distribution of sand dunes, bare lands, dried beds of lakes, dried wetlands, and other places along the region’s dominant wind route was determined using the remote sensing technique and the MODIS sensor images extracted from Aqua and Terra satellites. Moreover, 70% and 30% of the identified sources of dust were randomly assigned to training and validation datasets, respectively. Then, the potential areas for generating dust were investigated using the maximum entropy algorithm and the MAXENT software. Finally, a model was developed for identifying the potential areas of dust generation with the highest accuracy. After developing a complete model comprising of all relevant variables, the modeling was replicated to the number of variables, whereby each individual variable was removed from the modeling process in each replication of the process. Therefore, the influence of each variable in predicting the desired areas was evaluated and the forecast map of dust generation centers was improved. Then, the results of the forecast map were validated using the method under the ROC curve.

This study found that sensitive areas such as the Helmand River bed, Hamoon Lake, Darmian, Nehbandan, eastern parts of South Khorasan Province, Sarakhs, Tabas, Iranshahr, etc. had a high potential for dust generation. According to the input maps extracted from the maximum entropy model, the dust-prone areas fell within the range of sand dunes, whose lands lacked any vegetation. Located in the direction of winds with more than 10 meters per second velocity, the areas are mostly spread in saline lands, barren lands, and dried water bodies, possessing less than 100 mm precipitation rate, low slope, and maximum temperature rate. It was also found that the AUC values were 0.78 and 0.75 ​​in the calibration and validation stages, respectively. On the other hand, according to the validation of spatial forecasting models and the current literature in the field of ROC curve method analysis, it can be argued that due to its over 70% accuracy, the maximum entropy model can perform well in predicting dust-prone areas. Also, the results of the Jackknife test indicated that wind speed, precipitation, pedology, vegetation, and land use were the most important variables involved in the prediction of dust generation centers, with the model being highly sensitive to such variables. However, factors such as maximum air temperature, slope, and lithology were found to have exerted a minimal effect on the occurrence of the dust storm in the study area. Moreover, according to the results of analyzing the correlation between the studied factors and the occurrence of the dust storm, the highest density of dust generation was observed in lowland areas where barren lands, salt marshes, sand dunes, and dried beds of water bodies existed. Possessing no vegetation, the areas are also located in the region’s local wind direction with high velocity.

Based on the study’s results, it can be argued that the maximum entropy model performs highly efficiently in identifying the potential dust-generation areas, considering the old dust-generating centers as dependent variables to prepare and produce a forecast map of dust-prone areas. Moreover, the model identifies the correlation between independent and dependent variables based on the extent of entropy to minimize the possibility of prediction error. Therefore, the model’s predictions are made with the lowest degree of uncertainty, whose results could be used and relied on for managing and controlling watershed erosion. On the other hand, the results suggested that the density and probability of dust storm occurrence varied in different parts of the region and that identifying dust-generation-prone areas was the first step in protecting the soil, controlling erosion, and managing sediment production. Moreover, the maximum entropy model showed an increase in wind speed and surface temperature throughout the study area, with a decrease in precipitation rate exerting a direct influence on the vegetation of the lowlands and plains where sand dunes, barren lands, and dried beds of wetlands are located. Finally, the maximum entropy model and other data mining models are recommended to be used for identifying potential areas of sediment production involved in the occurrence of dust storms to help improve the concentration of relevant executive projects in areas sensitive to wind erosion.

Affecting the hydrologic cycle, climate change may increase the chances of natural hazards occurrence, including drought, which is considered as one of the most destructive types of such hazards. On the other hand, considering the increasing trend of global temperature and its impact on local climates, climate change is predicted to alter the frequency and intensity of extreme events such as drought. Meanwhile, General Circulation Models (GCMs) have been used in recent decades to predict future climate changes under different emission scenarios, and various drought monitoring indicators have been developed to assess drought. Zarrineh River basin is regarded as one of the main sub-basins supplying the inflow of water to Lake Urmia, which is threatened by numerous long-term droughts. Therefore, as the drying of the lake may bring about a wide range of economic, social, and environmental consequences for the region, monitoring drought and implementing water resources management programs play pivotal roles in preventing the lake to get dried.

Located northwest of Iran, Zarrineh River basin covers an area of 12512 km2, being bounded by Iranian West and East Azerbaijan provinces and the Kurdistan province. This study used the meteorological data, including precipitation rate, and minimum and maximum daily temperature collected from four synoptic stations during the 1990-2018 period to simulate runoff. Also, the monthly runoff rate was collected from five hydrometric stations during the 1996-2017 period to calibrate and validate the SWAT model. Moreover, the data obtained from the general circulation model (HADGEM2-ES) and statistical downscaling methods (CCT) were used to simulate precipitation and temperature under RCP2.6 and RCP8.5 emission scenarios for the future period (2025-2049). Finally, the SPI was applied to evaluate the meteorological drought in the base and the future periods, and the SRI obtained from the outputs of the SWAT model was used to evaluate the hydrological drought.

The data collected from five hydrometric stations were parameterized and calibrated on discontinuous stream networks. Accordingly, it was found that the R2 values varied from 0.52 and 0.70 for calibration and from 0.44 to 0.73 for validation. However, the NSE values varied from 0.52 to 0.64 for calibration and from 0.42 to 0.64 for the validation stage. Moreover, the model’s outputs were found to be satisfactory for most hydrometric stations, indicating the applicability of the SWAT model to the ZRB. On the other hand, based on the CCT model under the RCP8.5, the results of temperature and precipitation variations throughout the 2025-2049 period indicated that compared to the observation period, annual precipitation would decrease by 2.9% in the future period, and the annual minimum and maximum temperature rates would increase by 2.4°C and 3.6°C, respectively. Furthermore, the analysis of the annual temperature and precipitation changes under the RCP2.6 revealed that compared to the observation period, the precipitation rate would increase by 3.6%, and the annual minimum and maximum temperature would increase by 1.8°C and 3°C, respectively. Moreover, the results of the SPI analysis for the future period under the RCP8.5 indicated the occurrence of the extreme drought event. However, while the frequency of severe drought did not change significantly for the future period under both scenarios, the frequency of moderate drought decreased for the future period compared to the base period. On the other hand, the most extreme hydrological drought in terms of the SRI was observed in basin 9 during the base period (equal to -3.02). It was also found that the most hydrological drought occurred in basins 10 and 2 throughout the base period. Furthermore, the most extreme hydrological drought for the future period was found as -4.13 in sub-basin 8 under the RCP8.5, which is greater than that of the base period. Discussion and

The results suggested the satisfactory applicability of the SWAT model for simulating runoff in Zarrineh River basin, as the model considers almost all the physical conditions of the basin for the simulation process, possessing a wide variety of inputs to do so. The results of the analysis of temperature changes for the future period showed that the average minimum and maximum annual temperature would increase in the basin. Moreover, the results of the analysis of annual temperature and precipitation changes under the RCP2.6 revealed that compared to the observation period, the precipitation rate would increase by 3.6%, and the annual minimum and maximum temperature rate would increase by 1.8°C and 3°C in future, respectively. On the other hand, according to the results of SPI and SRI analysis for the future period, it was found that the intensity of meteorological and hydrological drought would increase on average in the basin under both scenarios (RCP2.6 and RCP8.5). Also, the results of the RCP8.5 suggested the possibility of a more severe drought compared to the RCP8.5. Considering an increase in minimum and maximum temperature found for the future period, we can expect an increase in the evaporation rate, probably leading to an increase in the severity of drought and a decrease in water resources of the Zarrineh River basin, which, in turn, will reduce the discharge of the basin’s water flow to the Urmia Lake.

Ecotourism is closely related to the environmental potential of the ecosystem. Therefore, the feasibility study of suitable zones for ecotourism can help identify the relevant capacities, improve the developmental programs, protect the environment, and sustainably develop tourism, especially ecotourism. Moreover, more accurate identification of suitable zones for ecotourism and careful setting of well-designed plans to enable the zones’ potential in this regard seems to be an effective solution, playing a key role in sustainable development, improvement of the living standards in target communities, and maintenance of the ecosystem’s natural balance. Considered as a tourist destination in Iran, Kashan City enjoys a wide range of tourism capacities in terms of resources, attractions, infrastructures, facilities, etc. However, the ecological potential of the region has not been assessed scientifically in terms of ecotourism development. Therefore, this study sought to evaluate the ecological potential of Kashan City for developing centralized extensive ecotourism so that appropriate plans could be set for developing nature-based tourism, taking advantage of the city’s landscapes as the natural potential for sustainable development.

The current study attempted to assess the ecological potential of Kashan City for developing ecotourism using spatial analysis via ArcGIS, ENVI, and Google Earth software. Moreover, the tourism development model was used to assess the environmental potential of the study area. The criteria used in this regard consisted of climatic factors, including temperature, sundial, wind velocity, and precipitation. landscape factors such as slope, aspect, elevation, bedrock, and soil order, and ecological factors such as vegetation density, greenness value, plant height, and species were also taken into account. On the other hand, a set of base maps, a digital elevation model, spatial data, satellite images, climatic data, field surveys, and library studies were used to collect the required data. Finally, after providing the digital layers of the aforementioned indicators and applying the thresholds, the areas for developing ecotourism were classified into three categories, including highly suitable, suitable, and unsuitable areas.

The results of land suitability analysis for developing ecotourism in Kashan showed that 1859.58, 2690.27, and 476.97 sq. Km (42.2, 6.06, and 84.84 percent) of the total study area were highly suitable for ecotourism in terms of climatic, landscape, and ecological criteria, respectively. Moreover, 1859.58 and 2730.29 sq. Km (42.2% and 61.97%) of the region were highly suitable zones for extensive ecotourism in terms of climate and landscape criteria, respectively. On the other hand, the final results of the feasibility study for ecotourism development in Kashan city revealed that 60.63 and 39.34 percent (1730.86 and 2667.71 sq. Km), and 63.09 and 22.65 percent (2778.82 and 997.63 sq. Km) of the region enjoyed highly suitable capabilities for centralized extensive ecotourism, respectively. Furthermore, as can be seen in climatic factors maps, the northern to southeastern regions (as a continuous zone) have the highest land capability, and the western to southern areas have the lowest land capability in terms of extensive tourism development. Considering the same influence of climatic status on centralized and extensive ecotourism, the spatial distribution of proportional classes was found to be the same for both types of ecotourism zones. Moreover, as far as climatic factors are concerned, wind velocity and precipitation maps suggested the highest spatial diversity and temperature and sundial maps showed the least spatial diversity. On the other hand, considering their distinct role in the type of ecotourism and different alteration threshold of each parameter, the landscape factors offer a greater variety than the climatic ones. On the other hand, the slope, aspect, bedrock, and soil order maps revealed the highest spatial diversity, while the elevation map suggested the least spatial diversity. The high spatial diversity among vegetation-related factors could be attributed to the distribution of plant species (from shrubs to trees), the extent of greenness, vegetation density, plant height, and the range of changes in tourism classes in terms of such indices. In general, the highest land suitability belonged to the areas with maximum greenness.

The analysis of land suitability maps for the development of extensive centralized tourism in Kashan City suggested that the city was highly suitable for the development of various types of nature-based tourism, including ecotourism, mountain sports tourism (mountaineering and rock climbing), agricultural tourism, medical tourism and nature therapy (sand therapy, halotherapy, and desert tourism), bio-tourism (species and gene biodiversity), astronomy tourism, rural tourism, etc. Moreover, regions covered with vegetation are highly appealing for all types of tourism, especially if they are located in arid lands with natural shrubs and trees. On the other hand, more than 84% of the study area was found to be suitable for ecotourism development in terms of climatic and landscape factors, indicating the lack of vegetation in the region, which is quite justifiable as it is located in an arid land with a dry climate. In contrast, the highly suitable areas for ecotourism development are scattered throughout the region with a focus on the center, south, west, and east of the study area, most of which are covered with agricultural lands and vegetated mountainous areas. Furthermore, it could be argued that due to the reputation of Kashan City for its Rosa damascene flowers, the city’s agricultural areas are suitable places for agricultural tourism, bio-tourism, event tourism, and flower and rose festivals.

Collected from sixty-six meteorological stations, the most recent data concerning the intensity-duration-frequency curve in Iran have been recorded in 1374. While rain gauges are required for physically obtaining such data, the collected data may be fraught with inaccuracies, considering the fact that the meteorological data of the extremely remote areas may be impossible to be gauged. Therefore, intensity-duration-frequency formulas are used to reduce the rate of such inaccuracies. While many formulas have so far been developed to be used for obtaining the required data regarding intensity-duration-frequency curves, they could only be applied to those areas whose regional rates have been estimated. This study sought to identify and optimize such formulas’ rates together with the computational algorithms in the Urmia Lake’s basin. Then, the efficiency of the mass-fine computational algorithm and the genetic algorithm was measured and compared. Finally, the influence of climate change on intensity-duration-frequency diagrams in the basin was investigated using the nearest neighbor algorithm.

Considering the precipitation intensity data collected from Western Azerbaijan Province’s Regional Water Organization, first, the method for selecting the function of the precipitation’s intensity-duration-frequency was determined. Then, the fitting methods for the different return years’ functions of the intensity-duration were presented. As for the extraction of IDF curves, the required data regarding the highest annual precipitation rates in 30-, 45-, and 60-minute durations were obtained from the statistics published by the Iranian Meteorological Organization. Then, the precipitation rate was investigated in twenty-seven meteorological stations of the Urmia Lake, and the intensity-duration-frequency curves were made accordingly. Taking the extracted curves into account, the regional coefficients of Abkhezr’s equation were measured and optimized based on the Genetic and Particles Swarm algorithms. Then, to determine the measurement accuracy, the daily precipitation rates were extracted from five sample meteorological stations in terms of 2-200 return years and millimeters per hour unit using the SMADA software. Finally, the IDF curves were made based on the optimized rates and Abkhezr formulas.

The average rates of optimizing the coefficients of the Abkhezr formula with both algorithms mentioned above were found to be the same, bearing a very close prediction. Taking into account the average intensity and continuity rates of the IDF curves in terms of an integral diagram, the study undertook to compare the measurement of pre- and post-optimization IDF curves in five sample stations. Generally, the findings of this study indicated the accuracy of the Abkhezr Formula’s rates (with an acceptable closeness) in all meteorological stations of the Urmia Lake except for the Mahabad camp. It could therefore be argued that the average optimized regional rate are hundred percent fitted with the obtained rates. Discussion and

The findings of the study suggested a high accuracy of the Abkhezr formula’s coefficients in all Urmia Lake’s meteorological stations (with acceptable closeness) except for the Mahabad camp, with the Siyah-Ceshmeh station having the best fitting rate. In this regard, the fitting rate of the coefficients in the above-mentioned stations differed merely at thousandth and ten-thousandth decimal rates. On the other hand, the pre-and post-optimization IDF curves were found to have slight differences, bearing an acceptable fitting. Moreover, the comparison of the integral curves of the IDF parameters indicates the great consistency between the results of this study and the formulas developed by Abkhezr and Bell. Furthermore, a good correlation was found between the results of this study and the research findings of Aghajani and Kerami, which were based on Sherman and Bernahu's formulas. As t and T in Bell's formula can have a local dependence in each area, such a dependence has been included in Abkheder's formula based on regional coefficients. The results also showed that the PSO algorithm performed more efficiently in terms of optimization and its intended function is closer to zero, as it measures each particle with other neighboring particles, putting it in numerous cycles. However, the sensitivity analysis revealed a very slight difference between the two algorithms used in this study, suggesting that both algorithms could be applied.

 as one of the most critical environmental challenges in recent decades which has engendered environmental pollution worldwide (33, 3, 2), wind erosion occurs due to increased velocity and turbulence of the wind when blown on a cover-free surface (11), inflicting lots of economic and social damage on various sectors.There are several methods used to reduce wind erosion, including biological methods (seeding and planting), mechanical methods, and the methods used for strengthening the surface cover such as the application of different types of mulch (oil, polymer, biological, and mineral mulches) (21). In this regard, mulching should, as a last resort, be able to pass rainwater, penetrate into the ground, and maintain moisture while having sufficient required adhesive strength.Non-petroleum materials have increasingly been used in recent years to improve the stability of buildings, aggrandize the diameter of soil aggregates, and stabilize the soil against wind erosion. However, choosing a material as a soil stabilizer against wind erosion, replacing new mulch instead of oil mulch while considering the aforementioned factors, and taking the biodegradability of the non-petroleum materials into account are other crucially important factors to note in this regard. Therefore, this study sought to investigate the effect of mineral mulch (a combination of CaCl2 and MgCl2) on soil properties.

 The study area covered the sand dunes of the Rigboland desert located in Aran and Bidgol city, Isfahan. The mineral mulch used in the study was a stabilizing solution obtained from the evaporation of the brine of Iran’s central desert in the Khorobiabank region, known as the SS400 soil stabilizing solution (27). Chemical analysis of the solution indicated that it contained 30% CaCl2, 15% MgCl2, 5% NaCl, KCl, Ca (NO3) 2, and 50% water whose pH ranged between 5 and 6, with an average specific gravity of 1.5 g / cm3.On the other hand, in March 2012, mulch was sprayed directly to the natural field with three replications on three mounds of incomplete Barkhan-type sand dunes in Rigboland Aran and Bidgol regions to evaluate the influence of mineral mulch on soil’s chemical properties (Figure 4). To this end, samples of aeolian deposits were collected from three different depths of the hills in the study area with three replications (0-5 cm for the first replication with and without mulch; 5-10 cm for the second replication; and 10-20 cm for the third replication) prior to performing mulching. Finally, some samples were collected once more at the end of the experiment in May 2014 from the same three depths. It should be noted that 15,000 liters of mulch were applied per hectare.

 The results of paired T-test performed on the characteristics of different soil depths suggested that the mulched aeolian deposits did not differ significantly in both control and treatment groups in terms of N, CaSO4.2H2O, P, Cl, and OM characteristics in at all the depths studies (P> 0.01). However, the application of mineral mulch significantly increased the EC, pH, Ca, K, and CaCO3 at all depths, and N and Mg at the first and second depths (P <0.01).Mulches with different compositions and origins may increase or decrease the root's ability to absorb elements. In this regard, the current study found that mineral mulch significantly increased the soil’s pH (P <0.01), which could be justified if the Na and CaCO3 added to aeolian deposits as a result of applying such a mulch are taken into account.Furthermore, hydrolysis of Na and the dissolution of CaCO3 which eventually lead to the formation of hydroxyl anions could be regarded as the main cause of such an increase in the aeolian deposits’ pH under treatment mulch. Moreover, the comparison of the deposits’ pH made as a result of sampling with and without mulch revealed that the deposits’ pH would be higher if they are sampled with mulch, which can be justified according to the explanations provided above. On the other hand, some studies have reported that the aeolian deposits’ PH increased when treated with mulch (17), which is consistent with the results obtained in this study. However, the finding does not correspond with the results reported by some researchers (20 and 4).The significant increase in EC capability at different depths of the treatment group compared to those of the control group clearly confirms the influence of mulch on increasing the soil’s EC. Moreover, examining the soil’s EC capability at the evaluated depths showed a decreasing trend caused by the washing and transfer of the mulch-included solutes to lower depths, where the rate of ion transfer decreased with an increase in the soil’s depth.Also, mineral mulching significantly increased the soil’s K (P <0.01), which could be justified by considering the type and the origin of the mulch used, taking into account the fact that the initial solution was prepared by using the materials collected from the study area contained high amount potassium, a limited portion of which still remained active even after it was extracted from the solution (what remained from the solution afterward was used as mulch), causing a significant change in the amount of potassium in the soil. This finding is consistent with the results reported by some researchers (10, 13, and 14) who argued that mulch increased P and K in the soil.

 Considering the findings of this study in terms of the influence of mulch on the aeolian deposits’ componential elements and important chemical properties, including the deposits’ response, electrical conductivity, sodium absorption ratio, and the percentage of the exchanged sodium, all of which showed an increasing trend that led to salinization and alkalization of the deposits, and consequently to physiological dryness, and taking into account the fact that the mulch exerted no influence on the percentage of the aeolian deposits’ organic matter as the most important and effective factor in improving the physical, chemical, and biological conditions of the deposits, it could be argued that the mulch used in this study had no positive effect on the aeolian deposits studied. Therefore, this mulch is not recommended for stabilizing sand dunes and controlling dust.

The water resources of the earth have currently been reduced due to various factors such as rising population, and an increase in human activities, including the growth of urbanization and industries, and increasing agricultural and economic activities. Therefore, water shortage seems to be one of the most important crises that threaten the future life of living creatures. In this regard, arid and semi-arid regions are subject to more risks due to reasons such as climate change, drought, and excessive extraction of groundwater resources for industrial, agricultural, and drinking purposes. On the other hand, in addition to the increase in temperature, climate change will also cause changes in precipitation and evaporation rates, leading to the loss of large amounts of water by decreasing precipitation and increasing evaporation rates, respectively. In such a situation, the groundwater resources are highly pressurized, considering the continuous drop in the water level, the fact that the amount of harvest is always more than that of the recharge, and the irreparable damages that may follow. Therefore, this study sought to investigate the influence of climate change on the groundwater level of the Ravansar-Sanjabi basin and to analyze its results. To this end, first, the groundwater simulation was carried out by Mudflow code. Then, the effect of climate change on groundwater resources was investigated during the future period (2021-2040), taking into account different climate scenarios.

Known as a relatively rectangular plain with north-south extension, the Ravansar-Sanjabi plain is located in the northwest of Kermanshah city (the center of Kermanshah province) between 18'26°46'' to 00'50°46'' eastern longitudes and 00'25°34'' to 34’50’48’’ latitude''. According to the latest nationally published statistics, there are 881 wells in the Ravansar-Sanjabi basin with a discharge of 27 million cubic meters per year (Figure (3). Moreover, the main sources of the basin’s recharge are precipitation and the amount of water returned from exploitation wells, with approximately 17% of the precipitation in the area being considered as recharge.

As for the groundwater modeling, there was an acceptable correlation between the simulation and observation data under both stable and unstable states, indicating the appropriate performance of the MODFLOW simulation model in the Ravansar-Sanjabi basin. Moreover, the error-index value was found to be 0.95 for groundwater modeling with RMSE, suggesting an appropriate accuracy of the model in an unstable state. In addition, the values of the explanation coefficient and MAE were reported as 0.98 m and 0.87 m, respectively, falling in a suitable error range. On the other hand, the calibrated hydraulic conductivity values showed that the hydraulic conductivity values varied from 52 and 30 meters per day in the north of the basin. However, the greatest hydraulic conductivity values were found in the southeastern part of the basin, ranging from 16.5 to 29 meters per day. Also, the average values of hydraulic conductivity belonged to the central area of the basin, ranging from 8 to 12 meters per day. According to the results obtained for the selection of an appropriate climate model, it was found that out of 20 existing models, the HadGEM2-ES, CanESM2, and CSIRO-MK3-6-0 had the greatest values (15.5, 15.5, and 17.25, respectively), being selected as the best models in this research. Moreover, the results of climate change indicated that the precipitation rate did not change much throughout the study period (2021-2040). On the other hand, while changes in the precipitation rate were found to be small under the RCP2.5 scenarios, they were significant under the RCP8.5 scenarios, especially the reduction of precipitation in some months. As regards the temperature changes throughout the study period (2021-2040) under all three climate scenarios, the results indicated a decrease in temperature rates, with the lowest and highest decrease occurring under the RCP2.6 and RCP8.5 scenarios, respectively. Accordingly, the temperature is predicted to decrease by approximately 0.5 degrees Celsius in the worst case. It was also found that the groundwater level varied from 20 cm to 60 cm in all months, with the lowest balance reduction having occurred in January, and the highest balance reduction having occurred in April, May, and June. Moreover, according to the results of changes in temperature and precipitation under the three climate scenarios, it could be argued that the greatest and slightest decrease in the groundwater level will occur under the RCP 85 and RCP 26 scenarios, respectively.

 The development of urbanization and the increase of impervious surfaces, especially in arid and semi-arid regions with little atmospheric precipitation and a large volume of produced runoff, increases the risk of flooding, which is one of the most dangerous natural disasters. The main purpose of this research is to investigate and compare the performance of methods to improve the optimal management of runoff quantity and quality in Bandar Abbas city. Therefore, by simulating the operation of the surface runoff drainage system, it has been tried to identify the areas susceptible to flooding and to investigate the best operational solutions to reduce the flood volume and control the pollution load.

 In order to analyze the hydrological information, using the digital elevation model (DEM) of the region, the slope and the direction of the slope were calculated and the border of the sub-basins of the study area was determined. Then, using the urban land use map, the area of impervious surfaces was calculated. In this study, SCS, Hazen-Williams, and Dynamic Wave methods were used to calculate infiltration, loss, and trending, respectively. Also, qualitative sampling was done at the place of flow measurement simultaneously with precipitation events. At the same time as rainfall events, qualitative sampling was done at the place of flow measurement. The samples taken in the laboratory were qualitatively analyzed and the parameters of BOD, COD, NO3 and PO4 were measured. In order to provide the required quantitative data, the total runoff flow was measured in five rainfall events. After preparing the rainfall data related to the synoptic station, the aforementioned data along with other measurements made in the study area were entered into the SWMM model and the simulated discharge values were obtained. Then the values simulated by the model were compared with the measured real values. For this purpose, using the EPA-SWMM software, three management solutions of bioretention cells, green roof, and swale, were evaluated. Also, in order to analyze the sensitivity of the model, three parameters of channel slope, channel roughness coefficient and percentage of impermeability were checked on the results of the model and it was found that the percentage of impermeability creates the highest sensitivity in peak runoff. In this research, in order to better control the volume of floods and pollutants, three management practices of bioretention cells, green roof, and swale, were investigated in a part of the catchment area of Bandar Abbas city. For this purpose, the EPA-SWMM model was used. The obtained results of the validation showed that this model has the required accuracy for simulating urban runoff and this model can be used for urban runoff management plans and the design of the urban runoff drainage network in the study area.

 The results of the validation of the model in the 2, 5 and 10-year return period also showed that the peak discharge of the hydrograph of the basin outlet is close to the peak discharge obtained from the reasoning method in the different return periods. Considering that a 10-year return period is often used to design the surface water collection network, the results showed that in this return period, the green roof management solution has the best performance because it decreased 18.8% peak discharge in quantitative analysis. Also, the results showed that in all solutions, the percentage of peak runoff reduction increases with the increase of the return period. Another result of this research is that according to the qualitative results, the green roof management solution can significantly reduce BOD, COD and PO4 parameters. Therefore, the green roof management solution was chosen as the best solution to reduce the peak and load of pollution in the study area.Based on previous researches, the per capita increase of green space in Bandar Abbas city can be realized by using the green roof system. The results of this research related to the reduction of flood volume and pollution load using the best management solutions are consistent with other studies conducted in this field. Therefore, by using the best management solutions, it is possible to promote urban development with the least negative effects of urban runoff on the downstream areas and to minimize the decrease in the quality of surface water resources.