Environmental Erosion Research
Year:2011 | Volume:1 | Issue:2|Papers Count:7

Geographical information systems (GIS) -based soil erosion risk assessment models continue to play an important role in soil conservation planning. In the present study, soil erosion risk of Tange Bostanak watershed was determined within GIS-based Coordination of Information on the Environment (CORINE) soil erosion risk assessment method. The initially soil texture, soil depth and surface stoniness maps were created and intersected in GIS environment in order to generate an erodibility map. Then, Fourinier precipitation and Bagnouls Gaussen drought indicces were determined based on meterological data and erosivity was calculated. The composed erodibility map was co-evaluated within erosivity value and slope map of the site for composing potential erosion risk map. At the final step, the previous yearly land use maps from1988 and risk alternation were assessed. In conclusion, according to our results in Tange Bostanak watershed in 1988 the 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 0.15, 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 ways to decrease surface erosion and increase forage production is cultivation of Wheat. When we cultivate wheat with inadequate yields we can change the wheat species with perennial range species. This causes a decrease surface erosion and increase in forage production. The goal of this study is to assess this reasons for unsuccessful forage rain-fed cultivation of Onobrychis viciaefolia. This study was performed in 12 stations in Semirom and Chadegan. First there were permanent plots in every stage and the number of heaving sainfoin was noted. In every station we prepared a 1×1×1.5 meter soil profile and in the laboratory growing form of sainfoin was studied. Age of plants and physical and chemical characteristic of the soil and clay mineral were determined. Then clay minerals were analyzed by X-Ray diffraction. Results show that the soil consists of expanable clay minerals at a ration 2: 1. After raining during the cold season, water and snow that froze between the soil articles caused soil. Expantion which caused damage to the soil particles and increased soil erosion. Finally this expansion cause to go up the plant root and cut.

The aim of this research is to identify 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 and Calotropis procera species (totally 120 seedlings) were planted under the same conditions. These were the most common plant species used in Hormozgan planting projects. The seedlings were irrigated for two years and 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 significance levels. According to the results at the end of first and second years of planting, Prosopis juliflora seedlings had the best and Prosopis cineraria seedlings had the worse conditions. However according to results, we could plant Acacia nubica, Calotropis procera and Prosopis cineraria, seedlings in order of preference. Prosopis juliflora is a main species that can be used with the aboved mentioned species.

One of the most important environmental problems is soil erosion and its effects. Eutrophication, low oxygen levels and high nutrient (nitrogen and phosphorus) concentrations in reservoirs, channels and other water sources, is a common result of water pollution. Phosphorus (P) is one of the major plant nutrients as well as a major nutrient controlling eutrophication of surface water. The aim of the current study was to evaluate the effect of soil erosion on available phosphorus loss in the Kojour watershed. Discharges resulting from storm events were sampled at one fixed point in the river using a manual sampler. Results showed that minimum and maximum phosphorus loss through 7 rainfall events was 321 and 6707 g, respectively, with an average value of 2620 g. The result of modeling among phosphorus loss, sediment yieldrate in this period dramatically affected the loss of phosphorus. The result of modeling among phosphorus loss, sediment yield and runoff volume indicated that phosphorus loss could not be estimate by discharge, while sediment concentration estimated the loss of phosphorus with an 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, 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 a 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 delta areas. The Mehran river delta is located in the west of Hormozgan Province. 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 showed 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 slight change in coast line toward the Persian Gulf has been identified as a result of migration and deposition. The changes in the vegetation cover area in this zone which has a 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 atriplicoidesis one of the most important rangeland species of Hormozgan Province. With regards to its importance of it in domesticated animal nourishment, soil protection and raising honeybees this study on seed germination of Zygophyllum atriplicoides was carried out. In this investigation, the effects of seven pre-treatments with 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 grown in petri dishes for 14 days. This randomized experiment was replicated three times.According to the results, applying 0.2% KNO3 as pre-treatment on seeds showed higher values of seed germination percent, germination rate, plumage growth and vigor index. Warm water had higher values of radicle growth.

This study investigated the effect of rate and type of organic matter, and consecutive application of sodium on secondary particle size distribution. At first, a cropland soil was treated with two organic matter (manure and straw stubble) at different rates of 0%, 1% and 5%, with three types 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 with 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 depended on the rate of organic matter. Also, by increasing the SAR values, the frequency of particles in the fractions of 0.25<and 0.125<was increased. At higher levels of SAR, aggregates>1 mm showed more sensitivity against dispersion than those in the 0.25–1 mm fraction. The findings of this study revealed that besides the type and rate of organic matter, the SAR value of irrigation water is effective in particle size distribution. Burning straw stubble after harvesting lead to aggregate instability and increased soil environmental erosion.