Yahya Parvizi; Mahmood Arabkhedri; Mosayeb Heshmati; Mohammad Gheitury
Abstract
Soil degradation and erosion caused by human factors is the main threat to the functions of soil resources. The consequences of this phenomenon are reducing the sustainability and quality of production as well as environmental problems. Also, moisture stress, especially in rainfed lands, is a major limitation ...
Read More
Soil degradation and erosion caused by human factors is the main threat to the functions of soil resources. The consequences of this phenomenon are reducing the sustainability and quality of production as well as environmental problems. Also, moisture stress, especially in rainfed lands, is a major limitation to improve productivity in these lands. The use of subsurface water harvesting is one of the options that is prevalent in Zagros provinces, due to topographic and geological conditions. This research was designed to evaluate the effectiveness of the operation of the traditional system of land use change of dryland to grape, almond and alfalfa cultivation with supplementary irrigation using subsurface water harvesting system in improving soil permeability and inhibition of soil degradation and erosion in the Razin Watershed of Kermanshah Province. To do this, after selecting the study area, some of the diagnostic features of selected area including the soil permeability with the disk permeameter and the soil degradation and erosion condition with GLADIS method were measured by field measurements in the study area as well as the control area. In the laboratory, soil texture, bulk density, saturation percentage, lime, acidity, salinity, nutrient concentration and organic carbon storage were measured the soil samples collected in the operation and control area. The results showed that the hidden form of erosion, the gradual washing of fine particles and the coarse grains of gravel and pebbles remaining known as Armor, is the most important form of erosion in the region. In the long term, the construction of this system was able to remove this form of erosion and loss of soil from the region. Also, exploitation of the underground dam system and extraction of subsurface water harvesting within its scope, in addition to enhancing all soil quality indicators (including its organic carbon accumulation), resulted in a 23% increase in soil permeability capacity and soil erosion has inhibited 5.56 tons per hectare.
Mohammad Gheitury; Mosayeb Heshmati; Yahya Parvizi; Mahmoh Arabkhedri; Mahmod Tabatabaei; Khosroo Shahbazi
Abstract
Now a day, carbon sequestration is an important issue due to its serious role on global warming. The aim of this research was to evaluate mechanical measure of check dams on vegetation cover and soil carbon storage in watersheds of Kermanshah Province, Iran. These check dams were constructed in the drainage ...
Read More
Now a day, carbon sequestration is an important issue due to its serious role on global warming. The aim of this research was to evaluate mechanical measure of check dams on vegetation cover and soil carbon storage in watersheds of Kermanshah Province, Iran. These check dams were constructed in the drainage systems to reduce surface runoff velocity and optimize channel slope. Small sedimentary dams are made by gabions and dry structures. The soil and vegetation characteristics of the areas under mechanical operation and its control (severe grazing and grazing management) by field survey in selected sites of Gilan Ghab, Kangavar and Sarfirozabad. The plant biomass including canopy cover and plant root as well as plant litter were samplled along transect path using the quadrat plot. 36 soil sampls were collected from 0-20 cm of soil depths and were air dried and sieved through two milimeter mesh and analyzed in the soil laboratory. Soil organic carbon was measured by the Walkley and Black method and statistical analysis was carried out using SPSS software (version 19). Results showed that both mechanical (check dams) contributed to store 49.28 tonha-1 of carbon which was significantly lower than biological measures. It was concluded that vegetation cover has the most effects on carbon sequestration of the rangelands compared to mechanical methods.
Mosayeb Heshmati; Mohammad Ghaietury; Mahmood Arabkhedri; Yahya Parvizi
Abstract
Forest and land use change has many negative consequences including increased flooding, erosion, sedimentation and dust storms. The aim of the research was thus to investigate the effects of land use change in Zagros forests on erodibility and sedimentation via soil quality reduction in some forests ...
Read More
Forest and land use change has many negative consequences including increased flooding, erosion, sedimentation and dust storms. The aim of the research was thus to investigate the effects of land use change in Zagros forests on erodibility and sedimentation via soil quality reduction in some forests of Kermanshah Province, Iran. In order to achieve this aim, in the first step, afforest area and its adjacent rain-fed farm (which is developed during recent 10 years a result of forest land change), were selected and 35 soil samples were collected from the surface layer (0-20 cm). Then, the physico-chemical analyses were done on the soil samples. In the next step, soil erodibility factor was calculated and sediment yield was assessed using portable rainfall simulator. The results showed that six key properties of soil including soil aggregate stability, bulk density, organic carbon, total nitrogen, total absorbable potassium and cation exchange capacity were significantly (p<0.05) influenced by land use type. Additionally, in all tested samples, the total clay and silt content was about 80%, which resulted in the formation of soil with heavy texture. Subsequently soil erodibility factor (K) and sediment yield intensity in rain-fed farm was found significantly (P<0.05) higher than those of forest. According to the results and the role of Zagros forest ecosystem on water harvesting, aquifer recharge, flood and dust control, the current trend of changing forest landuse to arable lands accompanying improper tillage practice, crops residue burning and heavy machinery traffic in nearby rain-fed farms, cause accelerating global warming, increasing runoff coefficient and evaporation as well as water scarcity in future.
Saeed Nabipay Lashkarian; Mahmood Arabkhedri; Samad Shadfar
Abstract
Accelerated soil erosion and the production and transfer of large amounts of sediment are considered as one of the most important issues in many parts of Iran. Having enough knowledge on soil erosion and sediment production as well as identification of critical areas are necessary in order to reduce ...
Read More
Accelerated soil erosion and the production and transfer of large amounts of sediment are considered as one of the most important issues in many parts of Iran. Having enough knowledge on soil erosion and sediment production as well as identification of critical areas are necessary in order to reduce the adverse effects of this problem through soil and water conservation measures. Due to lack of gauge stations in the outlets’ of small watersheds, empirical models are considered as the proper tools for estimating soil erosion and sedimentation. One of these methods which was developed based on Meditranean sediment data, is the Factorial Scoring Model (FSM). Towards this, the main objective of this research is to compare estimated vs. observed sediment yields in some selected regions of Iran. For this purpose, 58 small chatchments equipped by reservoirs in their outlets were selected in Semnan, Central, Isfahan, Chaharmahal and Bakhtiari, West Azarbaijan, Lorestan, Fars, Golestan and Khorasan Razavi Provinces. The comparison of the results showed that all estimates of the original model (before calibration) are several times bigger than observed values obtained by surveying (0.44 to 459.44 t.km-2.y-1). In order to correct the model coefficients for Iran, calibration was performed in two scenarios; once using all data and in the second secenario after allocating data into three geographic regions, which in both cases resulted in significant improvement of estimates. The Nash‐Sutcliffe Efficiency coefficient for all catchments was 0.39, and for Central, Zagros and Northeast regions were 51.1, 0.66 and 0.78, respectively. Based on obtained findings, the application of original FSM must be avoided in study areas. Instead, we strongly recommend using calibrated models based on observational values for different geographic regions.
Ramyar Aliramayee; Abdulvahed Khaledi Darvishan; Mahmood Arabkhedri
Abstract
Various factors such as rainfall intensity and slope affect hydrological processes such as infiltration and runoff. Study on rainfed soils is very important because of intense degradation and sensitive ecosystem. The present research was conducted to investigate the effect of rainfall intensity and slope ...
Read More
Various factors such as rainfall intensity and slope affect hydrological processes such as infiltration and runoff. Study on rainfed soils is very important because of intense degradation and sensitive ecosystem. The present research was conducted to investigate the effect of rainfall intensity and slope gradient on infiltration and surface runoff using rainfall simulator in rainfed lands of Kalaleh region, Golestan Province. To achieve the study purposes, four rainfall events with the intensities of 33, 64, 80 and 110 mm hr-1 and duration of 15 min were simulated. Three slope gradients of 6, 12 and 25% were selected and infiltration and surface runoff were measured in four 25×25 cm2 plots. The results showed that the infiltration average rate and runoff average coefficient were increased with increasing rainfall intensity and slope gradient. The main and interaction effects of rainfall intensity and slope gradient on infiltration and surface runoff were significant (p≤0.01). The results of subgroups of rainfall intensity and slope gradient using Duncan test showed that two turning points in hydrological response of plot are distinguishable, one between rainfall intensities of 64 and 80 mm hr-1 and another between slope gradients of 12 and 25%. In other words, at the rainfall intensity more than about 70 mm hr-1 and the slope gradient more than about 15%, average infiltration rate and average runoff coefficient were significantly decreased and increased, respectively. These results emphasized on land use management via avoiding change from rangeland to rainfed land especially when the slope is more than 15%. Agricultural and land cover management was also emphasized especially in high rainfall intensities (more than 70 mm h-1).
