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

Rain simulator is a device that can create raindrops on small plots with similar rain characteristics in nature. Gachsaran and Aghajari formations are one of the most erodible formations of Fars group. Gachsaran Formation has salt, anhydrite, colorful marls, lime and some shale. The Aghajari Formation consists of gray and brown limestone sandstone and gypsy red marl and siltstone.

In this study, in order to compare the role of Kamphorst rain simulator height in changing different erosion components, some parts of Margha and Gach Kuhe watersheds with an area of 1609 and 1202 hectares were selected. Kamphorst rain simulator was located in rangeland use at 40 and 200 cm height and in total, in both structures performed in 12 point and three times replicates and erosion different components such as runoff, sediment and infiltration were obtained at precipitation intensities of 1 and 1.25 mm/min.

The results showed that sediment yield in both structures did not change significantly compared to rain simulator height, while runoff and infiltration were more sensitive to rain simulator height and infiltration was the highest sensitivity to change in rain simulator height in both structures.

In general, the results showed that with increasing the rain simulator to 200 cm, the obtained data such as sediment and runoff and infiltration are more reliable and can be closer to normal conditions due to the somewhat close rain droplet speed. In addition, more accurate results are created in runoff and sediment estimation and soil infiltration, which can be more useful in designing watershed management structures.

Underground dam is an important hydraulic structure in management water in the arid and semi-arid areas. The aim of this research was to identify appropriate sites for constructing underground dams, where they do not limit construction of other such dams in this region. By benefiting from the Boolean logic, and using the physiographic, topographic, geological, land-use, fault, and aqueduct criteria, the regions that had no limitations for the constructing underground dams were selected. Using the analytical hierarchy process as well as the quantity and quality criteria of water, economic and social, dam reservoir, capacity and land-use, suitable sites for project construction underground dams were prioritized. The inconsistency rate in this research was 0.05. Investigation of the inconsistency rate indicated that the scoring performed for the criteria and sub-criteria studied here were acceptable. The results of prioritization of the region indicated that the watershed slope was the most important criterion in determining suitable site for such projects, thus constructing dams at steep slopes was not economical. Furthermore, given the geological conditions of the region and high score of this criterion in constructing underground dams, this criterion should be paid more attention to in such constructions. Overall, the results indicated that the regions located in the western and central parts of the watershed had a higher score for underground dam construction. Considering the importance of underground dam in dry and semidry regions, it can be stated that by constructing such dams in these regions, it is possible to improve the management of water resources.

To apply scientific and proper management of rangeland ecosystems, having information on health and functions indices of ecosystem is required. Using landscape function analysis, the present study deals with assessing and comparing of ecological indices in northern and southern landscapes, Darehkonari Khashab of Gachsaran. Length and width for ecological patches in northern landscapes in species Astragalus fasciculifolius Boiss, Centaurea intricanta Boiss, Cousinia multiloba DC, and inter patches­(bare and litter), in southern ones on species Cousinia multiloba DC, Stachys byzantina C. Koch, Stachys byzantina C. Koch and Cousinia multiloba DC and inter patches were recorded along three 50 m transects across both southern and northern aspects. In addition, eleven soil surface indices were measured. These indices belong to three main characteristics of soil stability, infiltration and nutrient cycling. The results showed that the indices of stability and nutrient cycling in both landscapes have a significant difference (p 0.05). The main ecological indicator of northern and southern landscapes are C. intricanta and S. byzantine C. multiloba, respectively.

Evaluation of changes present in soil and water resources due to operation implement of floodwater spreading is necessary to assess their positive or negative resultant effect. Rate of the internal sediment to diversion spreader channels، surface sedimentation and aggregation of the spreading field depth are most important effective attributes on the yield of floodwater spreading systems. These factors can change physical and chemical properties of studied field، as، by measuring of the infiltrate depth sedimentation of can achieve influencing depth of floodwater. To determine the effect of flooding spread on the sediment infiltrate rate in the field depth of Gachsaran floodwater spreading، from 0-15، 30-15، 30-45 and 45-60cm of the soil surface of spreading field and control were sampled. Granulometry of all samples was done using dry sieve and hydrometric analysis and then percent of the sediment grains with size of less than two millimeters were subjected to analysis of variance (ANOVA) by Duncan t-student test for 80 sampled samples. Results showed that deep entering of the sediments into drilled profiles to 30-45cm was completely distinct which can affect on the soil physical and mechanical properties. However، after the 30-45cm depth، the impact of floodwater spreading was minimal. The infiltration of each studied layer is the most important feature which will change from surface to the depth of spreading belts، so that by increasing infiltrated fine particles in the depth and blocking pores، the soil layers are clogged and in result reduce the infiltration rate، sharply. This state was more remarkable in the spreader belts surface. Furthermore، by depositing the sediments in the surface (0-15cm depth)، an impermeable and earthen layer is created which prevent from infiltrate the particles and even water into soil depth. Generally، with determine of the deposited sediment level in the spreading belts and also its deep infiltrate rate can provide effective and practical decision to improve efficiency and easy maintenance of the floodwater spreading systems or even not use this method.

To assess clay mineral compositions and the possible effect of floodwater spreading on the change of clay mineral types in the Gachsaran floodwater spreading station, samples were first selected from the control and floodwater spreading fields. Subsequent to sample preparation through X-ray, the clay minerals were determined carefully. According to the results, a number of clay minerals including Illite, Chlorite, Kaolinite and also swelling Smectite were identified in this area. Regarding all the samples, there were no significant differences in abundance of clay minerals, while some negligible differences were detected in the value of Illite and Smectite in relation to the control field samples; In fact, the amount of Illite and Smectitein of all samples were five percent more and lesser than that of control, respectively. In addition, at least 30 percent of the clays were Smectite. Therefore, after each flood in shallow sections and even in deep ones, Smectite clays swell immediately; that it can severely affect the soil permeability and subsequently a double effect on reducing water penetration. Such phenomenon can result in a number of remarkable problems in achieving the goals of floodwater spreading systems. Significant amounts of Illite clay showed that soils of the region under study were somewhat youth and in primary evolution. Although the possibility of structural changes of minerals in the floodwater spreading networks is theoretically expected to take place potentially, Gachsaran floodwater spreading station appears to have no significant effect on creating new clay minerals.

Floodwater spreading is a simple method for extracting floods which in most parts of the country are usually lost. However, floods are usually rich in nutrient and can fertilize coarse-grained alluvial fan and floodplain sediments. Therefore, the aim of this research was the investigation of the effect of floodwater spreading on soil fertility in Gachsaran floodwater spreading station. For this purpose, for measuring N, K, P, EC, pH, organic carbon and soil texture, the soil and sediments were sampled in two depths of 0-15 and 15-30 centimeters from first and second strips of floodwater spreading and also from the representative area (area where floodwater spreading is not performed), and the samples were analyzed in the laboratory. According to the results, the amount of P, K, N, C and EC in two areas did not show meaningful difference but pH, percentage of clay and silt, decreased and increased, respectively in floodwater spreading and representative area and showed meaningful difference. It is concluded that there was no change in soil fertility due to floodwater spreading.

Using of different systems of soil plough after changing unconsciously and non-scientific of land use, other soil physical and chemical characteristics affected. This fact, especially in marginal lands and mountainous regions is more visible. This research compared with the purpose of studying land use changing on some soil physical and chemical characters like very tiny sand percent, pH, Ec, clay percent, sand percent, silt percent, soil moisture, calcium carbonate in Gachsaran and Aaghajari formation. So that in aghajari formation 7 points and with 3 replicates and in gachsaran formation 6 points and with replicates in three land uses range, residential and agricultural land uses sampling of soil was done. Sampling of the depth 0-20 cm soil was done. After tests implement are concerned, the results were investigated. According to the results, range land in two Aghajari and Gachsaran formations in terms of clay percent, sand, EC, pH, moisture and Calcium Carbonate a meaningful difference have, and in other cases was not seen any disagreement. between agriculture land use in two Aghajari and Gachsaran formations in terms of very tiny sand percent, sand, clay, moisture and calcium carbonate meaningful difference have, and in other cases was not seen any disagreement. In residential land use in two Gachsaran and Aghajari formations only in clay percent and EC, there are a meaningful difference, and in other cases was not seen any disagreement. In each formation also land uses had effective role in soil physical and chemical characteristics.