جستجوی مقالات مرتبط با کلیدواژه « عمق » در نشریات گروه « آبخیزداری، بیابان، محیط زیست، مرتع »

The habitat suitability model is a common method for assessing the habitat needs of fish in freshwater systems. The aim of this study was to investigate the habitat suitability of Kiabi loach (Oxynemachilus kiabii) in the Dinor River, Kermanshah province, Iran. For this purpose, 7 stations along the Dinor River were sampled in April 2017 using an electrofishing device. In addition to recording fish abundance, environmental characteristics including water temperature, water velocity (m/s), depth (cm), river width (m), average bedrock diameter (cm), alkalinity (pH), electrical conductivity (EC), and total dissolved solids (TDS) was recorded at each station. The habitat suitability index was evaluated according to the relationship between environmental variables and fish abundance. Based on the results, the most desirable habitats for O. kiabii in the Dinor river are areas with a river width of 6-7.2 m, river depth of 26-34 cm, water flow velocity of 0.17-0.45 m/s, water temperature of 22-23 °C, EC values of 300-350 μS/cm, pH values of 7.80-8.92, TDS values of 580-610 mg/l, and average diameter of bedrock less than 5-6 cm. In the present study, the value of habitat suitability index (HSI) for O. kiabii was determined to be 0.51. Overall, the results showed that the Dinor River, in terms of habitat characteristics, compared to other fish species (such as Alburnus sellal), has a moderate suitability for the Kiabi loach. This indicates that the expansion of human activities in the Dinor River basin has disrupted the habitat range of this endemic species. Therefore, conservation priorities need to be considered by fisheries experts and managers in order to conserve and manage the stocks of this valuable species.

Petroleum hydrocarbons are among the major organic environmental pollutants whose toxicity and carcinogenicity effects have raised great concerns while the numerous available physical and chemical methods to remove petroleum hydrocarbons are rarely employed due to their extreme costs and harmful side effects, biological methods, including phytoremediation, have attracted wide attention during the recent years. The current study used sorghum (Sorghum vulgare) and barley (Hordeum vulgare) to decrease petroleum hydrocarbon content of contaminated soil around Isfahan Oil Refinery (Isfahan, Iran). It also assessed the concentrations of petroleum hydrocarbons and petroleum-degrading bacteria at different depths of soil following phytoremediation. Polyvinyl chloride (PVC) pipes (20 cm in diameter and 130 cm long) were employed for phytoremediation. In each pot, hordeum or sorghum seeds were separately sown approximately 1-2 cm below the soil surface. Thirteen weeks after sowing of the plants, soil columns were sampled at 25, 50, 75, and 100 cm depths and concentration of petroleum hydrocarbons and number of oil-degrading bacteria was determined. Statistical analyses indicated the two plants to reduce the concentration of petroleum hydrocarbons to a significantly higher extent (23%-35%) than the control treatment Obviously, such an effect was only detected in depths where plant roots penetrated (especially 0-50 cm), i.e. the absence of roots in deeper parts of the soil column (50-100 cm) was accompanied by lower number of oil-degrading bacteria and higher concentration of petroleum hydrocarbons. Accordingly, future studies are recommended to investigate the efficacy of landfarming and stimulation and injection of oil-degrading microorganisms in eliminating deep soil contamination.

The aim of this study was the selection of appropriate depth and spacing of pipe drains in order to decrease installation costs of drainage network per unit area. A model was developed to estimate construction costs using soil and plant data for Behshahr region. The results showed construction costs decrease with increasing installation depth، as reduction in costs in shallower drain depths (<1. 8 m) was higher، compared to greater drain depths (>1. 8 m). When environmental effects are considered in addition to installation costs، the optimum range of drain depths are between 1. 6 to 1. 8m whereas the minimum costs would be related to the 2. 8m depth. Furthermore over- and under-estimation design factors and transportation distance for envelope materials had considerable effect on construction costs، and this effect was more intense for shallower drain depths.

Estimation of design flood is the first step in hydraulic structures and flood control projects designing. On the other hand، estimation of runoff and flood، need to precipitation and design rainfall informations. Therefore، with respect to the spatially variations of rainfall and providing Depth–Area–Duration relationship، we can obtain suitable patterns of rainfall for estimation of design rainfall values in various locations. In this study، after gathering all storms in Hamedan، Qazvin and Zanjan provinces، 9 maximun and overall storms from 50 storms were selected. The results showed that between all of storms،the November 5،1994 storm is maximum and overall than others. The number of stations varies from 116 – 125 of 169 total stations in different storms. After drawing rainfall accumulation curves for climatology raingage stations، the hytograph curves were drived for noun recorded stations. After that the rainfall maps provided for 9 storms. Finally Depth–Area–Duration curves provided using rainfall maps. Using this curves were derived rainfall amount in any region and duration.