zahra ganji norouzi

The change of land use and the reduction of permeable surfaces due to urban development have caused an increase in the peak discharge and volume of runoff due to rainfall, which causes flooding of roads and damage to urban areas. By accurately estimating the amount of runoff and properly designing the urban drainage network, as well as managing this runoff, the damages of urban floods can be reduced. SWMM rainfall-runoff model is one of the most efficient models in the design of drains and urban runoff management. Since the hydrological models must be evaluated before use, in this study the SWMM model was evaluated using 6 rainfall-runoff events for the city of Shahrood and the efficiency of the urban drainage network for floods with return periods of 2 to 15 years was investigated. For this purpose, six flood hydrographs of precipitation events was measured at the two main outlets of the city. he results showed that the SWMM model with the mean square root of the normalized error (NRMSE) of about 20% and R2= 0.90 in the validation stage has a suitable efficiency in simulating the flood hydrograph. Also, also the examination of the performance of urban drains showed for precipitation with a return period of 2, 5, 10 and 15 years, 9.1, 31.8, 36.4 and 41% of the canals are flooded, respectively.

With increasing population and water consumption in agriculture and industry, the entry of various contaminants into the environment and soil and water resources has been increased. Cadmium heavy metal is known as one of the polluting elements. In addition to toxicity, it has adverse effects on the health of living organisms, too. In this study, the adsorption method was investigated by the three adsorbents of sepiolite clay, corn biochar, and clay and corn biochar complex on the removal of cadmium metal from water. For this purpose, experiments related to adsorption isotherms and adsorption kinetics were performed by the three adsorbents. Parameters affecting the adsorption process include type of adsorbent, change in initial concentration of cadmium solution, and changes in adsorbent contact time were investigated. The adsorption capacity of the adsorbents increased with increasing cadmium concentration from 150 to 800 mg/l, but the adsorption percentage decreased with increasing concentration. The results showed that the highest adsorption capacity in cadmium was related to corn biochar, while the clay-biochar adsorbent had more adsorption capacity than clay adsorbent. Langmuir and Freundlich isotherms for each element and adsorbent were investigated to study the adsorption process. It was found that the adsorption of cadmium by the adsorbents follows both models. Freundlich model with the highest coefficient of determination (R2) and the lowest sum of squares of standard error (SSE) showed the best fit with laboratory data. The effect of adsorbent contact time on the adsorption rate was investigated and found that the adsorption efficiency increased with increasing contact time. Fitting quasi-first-order, quasi-second-order, Elovitch, and intra-particle dispersion models for cadmium at concentrations of 150 and 600 mg/l was performed at 30 to 1440 min. The Elovich model at concentrations of 150 and 600 mg/l cadmium showed the best fit with laboratory data. At concentrations of 150, clay-biochar complexes showed better adsorption performance, but at other concentrations of cadmium, biochar was a better adsorbent than the other two adsorbents. Based on the results inferred from adsorption experiments, it can be stated that the corn biochar compared to clay and biochar and clay and biochar complex compared to clay has a high ability to remove heavy metals from contaminated water, which can be used as a cheap and practical material used to remove contaminants such as cadmium.

In countries with arid and semi-arid climates, conserving water resources is important. For this purpose, different models were presented to determine the vulnerability of areas. In this research, a vulnerability map of Sabzevar aquifer has been prepared using a drastic model. Sabzevar aquifer located in the northeast of Iran with an area of 5455.4 square kilometers has a dry and desert climate with hot and dry summers and cold winters. The drastic model is obtained through 7-layer overlap (groundwater depth, net nutrition, aquifer environment, soil type, topography, influence of unsaturated area and hydraulic conductivity of the aquifer) and shows a detailed map of the aquifer vulnerability. ArcGis10.5 software was used to draw the drastic model map. The numerical value of the drastic model in the study area is between 81 and 159 (from low vulnerability to high vulnerability). Drastic map showed that a very small area from the west of the study area has low vulnerability and the central areas of the plain have high vulnerability. Other parts of the region are moderately vulnerable. Shallow groundwater depth in the central areas of the plain and also low slope in the above area has the greatest impact on the vulnerability of the region. Due to the volume of agricultural activities in the central areas of the plain, measures should be taken to prevent possible contamination of the aquifer. Due to the fact that the concentration of nitrate in groundwater sources was not available in the study area, so electrical conductivity was used to validate the zoning of the drastic model. The overlap of electrical conductivity with the drastic map showed that the electrical conductivity was high in the center of the vulnerable plain. This can also confirm the accuracy of the drastic model.

Introduction Conservation and improvement the soil structural stability play a key role in soil management in agro ecosystems especially in arid and semiarid region with high erosion potential. Soil structure is an important soil physical property and has many effects on other soil physical, chemical and biological behaviors such as retention and movement of water, nutrients and pollutions, soil hydraulic and mechanical properties, soil aeration and erosivity. Wetting and drying cycles are one of important environmental factor affecting soil structural stability. Previous studies showed inconsistent results about the positive or negative effects of wetting and drying cycles on soil stability. This study was conducted to investigate the effect of wetting and drying cycles on the soil structural stability in the presence of safflower residues. Materials and Methods The agricultural soil was collected from the soil surface layer (0–20 cm) of Shahrood in Semnan province and passed through a 4 mm sieve. An experiment was conducted including two treatments i.e. number of wetting and drying cycles (0, 1, 2, 4, 8 and 10 cycle) and amount of safflower residues (0, 1 and 2 g 100 g-1 soil ). Plant residues were collected from safflower fields and after drying, milled and passed through a 1 mm sieve. Then crop residues were mixed into soil. The wet and dry cycles were applied during 2 month. In wetting periods the soil was kept in filed capacity and in dry periods the soil was kept in electrical oven in 40°C. The soil organic carbon and soil diluted acid carbohydrate concentration were measured at the end of the experiment. The soil structural stability was measured using high energy moisture curve. The soil drainable pores, soil suction at inflection point, stability index, stability ratio and Dexter's S index were calculated. Results and Discussion The greatest soil organic carbon was observed in control treatment (0 wet and dry cycle) and then it was decreased by increment of cycles in all crop residues levels. These cycles improve the microbial activity during the rewetting process and increase decomposition of crop residues. The soil organic carbon and diluted acid carbohydrate were highest in treatments including 2 g residues 100g-1 in all studied wet and dry cycles. The greatest soil drainable pore volume and the lowest soil suction at inflection point were found in treatment including 4 wet and dry cycles. The results showed that 2 and 4 cycles increased the soil drainable pore volume by 58 and 106 % compared to the control treatment (no applied cycle). More increment of wet and dry cycles decreased the soil drainable pore volume and this factor was declined by 40 % in 10 cycles treatment compared to 4 cycles. It means that wet and dry cycles can improved the soil structure because of rearrangement of soil particles and improvement of soil particle contact points. However, the high number of wet and dry cycles destructed the aggregate and decreased their stability. In addition, the physical protection of soil aggregates from soil organic matters declined through aggregate breakdown. This phenomenon provided fresh organic matter for decomposers and consequently the aggregate stability decreased. Appling only one wet and dry cycle could not significantly improve the stability ratio. This ratio improved considerably when 2 and 4 cycles were used. Following the aggregate breakdown in treatments including more than 4 cycles, the stability ratio decreased in all crop residue levels. Our results showed that the greatest and the lowest volume of coarse and medium pore were observed in 4 and 10 wet and dry cycles treatments but the greatest and the lowest volume of fine pores were observed in 10 and 4 wet and dry cycles treatments. It means that the structural stability improvement during 0-4 cycle changed the pore distribution and made larger pores but the aggregate breakdown with more than 4 cycles changed the pore volume again and increased the portion of finer pores. Conclusion Our results showed that the low number of these cycles can improve the soil aggregation and aggregate stability but the high number of these cycles has negative effect on aggregate stability. However, the presence of organic matter in soil can decreased the negative effect of wet and dry cycles. These results confirmed the importance of incorporating crop residues in to the soils after crop harvest.

Soil improvement with plant residues incorporation influences many soil properties. This study was conducted to investigate the effect of apricot and winter olive leaves (0, 1 and 3 g residue 100g-1 soil) on the soil structural stability using high energy moisture curve (HEMC) method in different soil salinity levels (1, 5 and 10 dS m-1). Apricot residues increased the soil organic carbon content and diluted acid carbohydrates and decreased the soil basal respiration more than the winter olive leaves. Increasing residues and salinity levels have also increased the soil organic carbon and the carbohydrates concentration in the soil. Also, the soil basal respiration has been reduced by increasing salinity. There were no significant differences between the apricot and winter olive residues in terms of their effectiveness on the soil drainable porosity (VDP), the soil suction in inflection point (τd) and the stability index (SI) in slow wetting method. However, the apricot leaves increased the soil drainable porosity and the stability index more than the winter olive in fast wetting method. This finding shows the different response and the structural instability of the soil for the two proposed organic matters. Plant residues increment by improving soil carbon and carbohydrates concentration, and salinity increment by improving divalent cation concentration have enhanced the soil stability ratio and the soil VDP ratio in both; fast and slow wetting methods. The results of this study showed that the application of native crop residues in the soils with low organic matter could improve the soil physical characteristics and these changes probably recover the soil physical fertility in the long term application.