فصلنامه پژوهش های فرسایش محیطی
پیاپی 2 (تابستان 1390)

Geographical information systems (GIS) -based soil erosion risk assessment models continue to play na important role in soil conservation planning. In the present study، soil erosion risk of Tange Bostanak watershed was determined within GIS-based Coordination of Infromation on the Enviroment (CORINE) soil erosion risk assesement method. Inittially soil texture، soil depth and surface stoniness maps were created and were intersected in GIS enviroment in order to generating erodibility map. Then، Fourinier preciptation and Bagnouls- Gaussen drought indicces determined based on metero-logical data nad erosivity were calculated. The composed erodibility map was co-evaluated within erosivity value and solpe map of the site for composing potential eroxion risk map. At the final step، the previous yearly land use maps which belong to years 1988، and risk alternation were assessed. In conclusion، according to our results in Tange Bostanak watershed in 1988 there have been low، medium، and high erosion risk values have changed. In 2007 there have been low، medium، and high erosion risks at 0. 82، 93. 99، and 5. 18 respectively، whereas in 2007 there have been low، medium، and high erosion risks at rates rates0. 15، 89. 99، and 9. 84%، respectively values have changed. i. Inter yeat comparison al of ternation to increase advantage of the medium and high erosion.

One of the most important waysto decrease surface evorsion and increase forgie production is cultration of When we cultivate corns and we have not any good yields we can change the corn species with perennial range species. It causes to decrease surface erosion and increase forage production. The goal of this study is assessing of unsuccessful reasons in forage rain fed cultivation of Onobrychis viciaefolia. This study was down in 12 stations in Semirom and Chadegan. At first we had permanent plot in every stage and the number of heaving sainfoin was noted. In every station was prepared a soil profile with 1*1*1. 5 meter and in laboratory growing form of sainfoin was studied. Age of plants and physical and chemical characteristic soil and clay mineral were determined. Then clay minerals were analyzed by X-Ray diffraction. Results show that soil has expansion clay minerals 2:1. That after raining in cold season، water and snow water between ingredient was heaved and cause to expand soil. This expantion cause to damage soil granule and increase soil erosion. Finally this expansion cause to go up the plant root and cut.

The aim of this research is، identifying the most appropriate species used for planting in Hormozgan province dune fixation projects. For this purpose، after Spraying Oil Mulch as a temporary stabilizer، 30 seedlings of Prosopis juliflora، Prosopis cineraria، Acacia nubica & Calotropis procera species (totally 120 seedlings) were planted under the same conditions. These، the most common plant species are used in Hormozgan planting projects. The seedlings were irrigated for two years and were protected against grazing. By measuring survival percentage، plant coverage and autumn period of each species، data were collected and examined by SPSS software at 0. 05 significant levels. According to the results at the end of first and second year of planting، Prosopis juliflora seedlings had the best & Prosopis cineraria seedlings had the worse conditions. [However as obtained results، could use planting Acacia nubica، Calotropis procera & Prosopis cineraria، species seedlings in order of preference، Also Prosopis juliflora is a main species that is used with aboved mentioned species.

One of the most important main environmental problems is soil erosion and its affects. Eutrophication، low oxygen levels and `high nutrient (nitrogen and phosphorus) concentrations in reservoirs، channel and other water courses، is a common water pollution feature. Phosphorus (P) is one of the major plant nutrients and also the major nutrients controlling eutrophication of surface water. The aim of current study was to quantities evaluation of the effect soil erosion on available phosphorus loss in Kojour watershed. Discharges resulting from storm events were sampled at one fixed point of river using the manual sampler. Results showed that minimum and maximum phosphorus loss through 7 rainfall events was 321and 6707 g respectively with an average value of 2620 g. Soil erosionThe result of modeling among phosphorus loss، sediment yieldrate in this period was dramatically affected on the loss of phosphorus. The result of modeling among phosphorus loss، sediment yield and runoff volume indicated that phosphorus loss didn’t estimate by discharge، while sediment concentration can estimate loss of phosphorus with estimation error of 26%. The results could facilitate the application of given methods obtained in the present study to other ungauged watershed with similar conditions and leading to the suitable soil and water management

Delta areas are dynamic features with changes occurring at many spatial and temporal scales due to catastrophic events. Change detection and providing fluvial map of changes are the main requirements for environmental and zonal planners in many studies. Geomorphic changes such as temporal and periodic changes in riverbeds are common events in all deltaic areas. The Mehran river delta is located in the west of Hormozgan State. Changes in various geomorphic features، shuch as riverbed migration، during a 21-year period، were detected and identified using landsat TM and ETM satellite data and topographic maps. Simple band subtraction and linear directional mean were used to identify changes in the case study. The results of this study show that the mehran river channel has migrated several times over the last 21 years so that several meanders and ox-bow lakes remain as a result of migration. Moreover a little change in coast line toward Persian Gulf has been identified as a result of migration and deposition. The Changes of vegetation cover area in this zone which has mangrove vegetation cover have been noticeable so that these covers have incremental trend according to undergone action in artificial forests. The results of this study may be used in an integrated coastal zone information system as it has been proposed for the Mehran river delta.

Zygophyllum atriplicoides is one of the most important rangelands species of Hormozgan province. With regard to importance of it in domesticated animal nourishment، soil protection and honeybees training، this study on seed germination of Zygophyllum atriplicoides was carried out. In this investigation، the effects of seven pre-treatments as hot water، sulphuric acid for 5، 10 and 15 minutes، 0. 2% KNO3، cold and controlled on seed germination of Zygophyllum atriplicoides were tested. Seeds were sown in Petri dishes for 14 days. This experiment was conducted completely randomized design with three replication. According to the results، applying 0. 2% KNO3 as pre-treatment on seeds had higher values of seed germination percent، germination rate، plumage growth and vigor index. Also، warm water had higher values of radicle growth.

This study investigates the effect of rate and type of organic matter and also consecutive application of sodium on secondary particle size distribution. At first step، a cropland soil was treated with two organic matter types (manure and straw stubble)، at different rates of 0، 1 and 5%، with three replicates during 4 months. Subsequently، four levels of SAR (0، 1، 10 and 30) were added to the pretreated samples through irrigation water. The results indicated that among different treatments، straw stubble 5% led to the most frequency of aggregates >1 mm and 0. 25-1 mm. It was found that increasing organic matter rate، the size and stability of aggregates increased. Aggregates >0. 25 mm were decreased with increasing the irrigation water SAR value، while this reduction was lower for higher rates of organic matter. This indicates that the effect of sodium on aggregate dispersion depends on the rate of organic matter. Also، increasing the SAR values، the frequency of particles in the fractions of 0. 25< and 0. 125< was increased. At the higher levels of SAR، aggregates >1 mm showed more sensitivity against dispersion than those in 0. 25–1 mm fraction. The findings of this study reveal that besides of type and rate of organic matter، the SAR value of irrigation water is effective in particles size distribution. Burning straw stubble after harvesting will lead to aggregate instability and soil environmental erosion increasing.