Abdulvahed Khaledi Darvishan; Jalal Faraji; Leila Gholami; Mohsen Khorsand
Abstract
The dynamics of rainfal erosivity (R), crop management (C) and soil erodibility (K) factors compared to the others (topography-LS and land management-P) is the most important note for the correct estimate of soil erosion at different time bases. Spatio-temporal estimates of soil erosion in the representative ...
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The dynamics of rainfal erosivity (R), crop management (C) and soil erodibility (K) factors compared to the others (topography-LS and land management-P) is the most important note for the correct estimate of soil erosion at different time bases. Spatio-temporal estimates of soil erosion in the representative paired watersheds are of particular importance due to their educational functions as well as the possibility of generalizing the results to larger areas of the country. Therefore, in the present study, while examining the dynamics of R, C and K factors in the Khamsan representative paired watershed, the distribution map of soil erosion in seasonal and annual time scales were prepared using RUSLE model for two water years of 2015-2016 and 2017-2018. The results showed that soil erosion in winter with values of 3.94 and 4.95 t ha-1 y-1 accounted for about 49 and 74% of the total erosion of the year, respectively. Considering the melting conditions in calculating the K factor for the winter along with the lack of vegetation in this season led to a higher estimate of soil erosion than other seasons. These results are in consistent with plots soil loss data recorded in different seasons and the higher concentration of suspended sediments in the rivers especially in March. In the water year of 2015-2016, the distribution of rainfalls in the autumn was much higher than in the spring, so that soil erosion in the autumn accounted for about 33% of the total erosion of the year. In the water year of 2017-2018, although the average annual soil erosion was less, but due to more distribution of erosive rainfalls in winter at the same time with the lack of vegetation on the soil surface and the soil melting, the rate of winter erosion was very high.
mohammad hedayatfard; Hamid Gholami; Seyed Masoud Soleimanpour; Arashk Holisaz
Abstract
Gully erosion is one of the most important phenomenons in land degradation and desertification, which upsets the balance of environmental resources and its sustainability. The aim of this study was to determine the effective factors on creation of gully erosion using data mining methods in Bayan Watershed ...
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Gully erosion is one of the most important phenomenons in land degradation and desertification, which upsets the balance of environmental resources and its sustainability. The aim of this study was to determine the effective factors on creation of gully erosion using data mining methods in Bayan Watershed in the north of Fars Province. K-Means clustering algorithms and CART decision tree were used to model gully erosion. The estimated accuracy based on the parameters affecting the creation area in the final model is 100% for the educational data set and 71.43% for the experimental data set. Results from measuring different variables from 40 selected gullies, including a target variable (creation area) and twelve predictive variables, like creation slope, vegetation, bare soil, surface gravel, surface litter, EC, pH, SAR, OM, clay, silt and sand in field and laboratory operations and the use of data mining techniques, showed that the creation of gullies in this watershed is a function of silt, acidity, bare soil, gravel and organic matter. These results showed the effect of vegetation and consequently, the presence of adequate organic matter in the soil as the most appropriate method for controlling gullies and the destructive and intensifying effect of bare lands without vegetation in intensifying gully erosion. Therefore, it is necessary to establish and establish permanent and compatible vegetation, to stabilize and improve soil structure and increase organic matter, and control and management programs, in lands with more silt, to be operated more carefully.
Mansour Jahantigh
Abstract
Soil erosion is an important chalenge in arid and semi-arid regions which has a negative impact on soil productivity and lose soil. Improper management of natural resources causes soil erosion. This reaearch was implemented in the north of Sistan and its aim was to idintyfy the effect of sand on increased ...
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Soil erosion is an important chalenge in arid and semi-arid regions which has a negative impact on soil productivity and lose soil. Improper management of natural resources causes soil erosion. This reaearch was implemented in the north of Sistan and its aim was to idintyfy the effect of sand on increased moisture in the plant root zone. For this pupose, three soil samples were collected from 0-50 cm depth and their pH, EC, C, Ca, Mg, K, Na, ESP, available phosphor, cations and texture were tested. This research had eight treatments including plant, soil and irrigation which have been done in split split-plot in four replication durig tow years. After plating a 20 cm layer of sand was applied on the soil surface in each pit. In this experiment, soil moisture was measured monthly and plant growth was measured in growing season. Statistical analysis of the data was performed using MSTAT software. Result showed that the amount of moisture was 28% higher in sand compared to other treatments at the level of 99%. According to the findings of statistical analysis on the impotance of methods used for soil moisture, the sand along with subsurface irrigation of toot had better groth at the level of 99% and were in class A and the other treatments were in class B. The conclusion was that sand causes decreasing in capillary, reducing soil evaporation, increasing moisture around root zone of the plants and water and soil conservation.
Majid Kazemzadeh; Ali Salajegheh; Arash Malekian; Abdolmajid Liaghat
Abstract
On average, 70 percent of the precipitation that reach Earth's surface, returns to the atmosphere through evapotranspiration, and this rate reaches 90 percent in arid areas. Meanwhile, watershed measures directly related to water, soil and plant, and ultimately to evapotranspiration on the natural resources ...
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On average, 70 percent of the precipitation that reach Earth's surface, returns to the atmosphere through evapotranspiration, and this rate reaches 90 percent in arid areas. Meanwhile, watershed measures directly related to water, soil and plant, and ultimately to evapotranspiration on the natural resources region (ecochydrology). In this study, in order to study the effect of biological activities of watersheds (enhancement and increase of vegetation) on the process of soil moisture and evapotranspiration changes, paired watersheds of Taleghan, Alborz Province were selected. In order to calculate evapotranspiration by soil moisture balance method, soil moisture monitoring points were selected using field and laboratory studies in three main areas (northwest, eastern and southeast) and three replications and at three depths of 0-20, 40-20 and 40 -60 cm during plant growth period in 2017. Data were analyzed by ANOVA method, and Duncan test. The results showed that the actual evapotranspiration in the treated watershed and control watersheds were not statistically significant and, respectively, they showed 181 mm and 159 mm in a period of growth. In other words, the actual evapotranspiration value in the treated watershed was 14% higher than the control one during the growth period. Also, the results showed that evapotranspiration under different aspect slopes had a significant difference. The total actual evapotranspiration in the northwestern slopes were 229 and 226 mm, in east slopes were 207 and 171 and in the southeastern slopes were 109 and 80 mm in the treated and control watersheds, respectively.
Seyed Masoud Soleimanpour; Majid Soufi; Mohammad Javad Rousta; Samad Shadfar; Ladan Jowkar; Hojatollah Keshavarzi
Abstract
Gully erosion is one of the main types of water erosion and is known as one of the destroying forms of land degradation and soil loss in the world. Therefore, knowing the most effective factors on extending this type of erosion is utmost important. Beside, management and control of gully erosion require ...
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Gully erosion is one of the main types of water erosion and is known as one of the destroying forms of land degradation and soil loss in the world. Therefore, knowing the most effective factors on extending this type of erosion is utmost important. Beside, management and control of gully erosion require knowing the most effective factors on gullies extension. So, the present study was performed to determine the most effective factors on gullies in Khorrambid Watershed, North of Fars Province through measuring the permanent gullies during 13 years (2004-2016). Results showed that the average of gully length extension was 21.67 m throughout this period. This data indicated that the length of gully extension was 1.67 m per year. Further, it is determined that the length expansion of permanent gullies in this region was a function of bare soil and saturated electrical conductivity, using SPSS and backward multivariable regression. In conclusion, it is suggested different management solutions to increase the soil resistance against the erosion be prioritized in management and implementation plans such as increasing adoptable cover vegetation for the natural condition of the region and exclude the area to restore vegetation cover and pay more attention to control erosion in gully head cuts.
Salahudin Zahedi; Kaka Shahedi; Mahmod Habibnejad Rawshan; Karim Solimani; Kourosh Dadkhah
Abstract
This study was conducted to evaluate the capability of the DHSVM model to simulate hydrological processes in a mountainous watershed with a minimum agricultural land use. The required climatic parameters were set for the daily time step. The inverse distance method was used to interpolate the climatic ...
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This study was conducted to evaluate the capability of the DHSVM model to simulate hydrological processes in a mountainous watershed with a minimum agricultural land use. The required climatic parameters were set for the daily time step. The inverse distance method was used to interpolate the climatic variables from the stations to the network cells. Time inputs to the model were prepared for the years 2008 to 2013. The land cover map was prepared using the supervised classification method of Landsat TM data. The stream network map was generated using the DEM map in ArcGIS software. The soil texture map was prepared using field sampling and in the laboratory. Primary tests to the determine sensitivity of input parameters showed that this model is sensitive to lateral hydraulic conductivity, exponential coefficient of hydraulic conductivity, porosity, field capacity, and minimum stomatal resistance. In this study, except for the lateral hydraulic conductivity and exponential decrease coefficient, all other parameters (soil and vegetation) were determined based on previous studies and field measurements in a similar way for both categories of data. The time series of the data were divided into three, warm- up or preparation periods (2008-2009), calibration (2009-2011) and validation (2011-2013). The model was calibrated using streamflow data from 2008 to 2010. Different efficiency criteria were calculated between simulated and observed flows. NSE value for calibrating was 0.59 and for validation was 0.606. In general, the results of this model implementation in the studied basin with the quality and quantity of input data to the model are satisfactory.
Elnaz Azartaj; Ali rasoulzadeh; Ali Asghari
Abstract
Soil and water are the most valuable national resources. Unfortunately in recent decade, due to land use change and vegetation cover degradation, most of the rainfall changed into runoff and in addition to loss of this vital resource, causes abundant loss of life and property by creating enormous floods. ...
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Soil and water are the most valuable national resources. Unfortunately in recent decade, due to land use change and vegetation cover degradation, most of the rainfall changed into runoff and in addition to loss of this vital resource, causes abundant loss of life and property by creating enormous floods. The aim of this study is to assess the effect of land use change from range land to agriculture with different percent of vegetation cover on runoff and soil erosion. For this purpose, three types of land use included preserved range land with 100 percent of vegetation cover; range land with 50 percent of vegetation cover and agricultural land (range land changed to agriculture) were identified in the study area. Then, in each land use, three slopes were determined (10, 15 and 24%). This study was carried out split plot experiment based on completely randomized design. In each land use and slope, runoff and erosion were measured in plots randomly using rainfall simulator with 1.5 mm.min-1 intensity and 15 min duration with 3 replicates. Results showed that the maximum of runoff, sediment mass and sediment density were in the range land changed to agriculture with 24% slope and the minimum of them were in the preserved range land with 10% slope. Also the results showed that the change of range lands to agricultures increase runoff 5 times. In the other hand, with increasing slope from 10 percent to 24 percent, runoff increased 1.7 times. Runoff coefficient was determined for 3 land uses and 3 slopes level. The maximum and minimum runoff coefficient were found 0.72 and 0.06 for the range land changed to agriculture with 24% slope and preserved range land with 10% slope, respectively.
Nadergholi Ebrahimi; Reza Sokouti Oskoee
Abstract
Mountainous rivers have characterized by steep slope, roughness due to bedrock and coarse aggregation, bed and marginal vegetation as well as severe and rapid spatial displacement of the surface substrate morphology. The protection role of vegetation in the river bank is known as an economic and environmental ...
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Mountainous rivers have characterized by steep slope, roughness due to bedrock and coarse aggregation, bed and marginal vegetation as well as severe and rapid spatial displacement of the surface substrate morphology. The protection role of vegetation in the river bank is known as an economic and environmental option that decreases hydraulic conductivity power of the river through the rising of roughness coefficient and rising water level. This study aimed to estimate the flow resistance and roughness coefficient of the river that is affected by the physical and biophysical factors of the Shahr-chay River bed in West Azerbaijan in three selected river reach. Results showed that none of the proposed equations for estimation of roughness coefficient depend on energy slope, but in general, without affecting flow, roughness coefficient in mountain streams depends only on the degree of submergence. Marginal trees can affect Froude number by increasing margin pressure and friction forces, also, enhancing the hydraulic depth, less than critical depth. It was also found the equation for estimating roughness coefficient both with and without marginal trees, have different coefficients and can provides roughness coefficient prediction possibility for mountainous rivers. Comparing the obtained relations both with and without its fringe of trees showed that fringe trees can increase the flow depth and roughness coefficient. Coefficient of determination of all mathematical relations was above 0.99 and calculated relative error was 0.001- 0.008 that demonstrates the suitability of the model to estimate the roughness coefficient.
Abolghasem Dadrasi Sabzevar; Ali Ghazanchian; Mohammad Namaki
Abstract
Social and economical evaluation of watershed management activities, is an important criterion for its validation. The main objective of present study was, identification and analysis of socio-economic impacts of watershed management operations implimented in Gosh village wich is located in 60 km north ...
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Social and economical evaluation of watershed management activities, is an important criterion for its validation. The main objective of present study was, identification and analysis of socio-economic impacts of watershed management operations implimented in Gosh village wich is located in 60 km north of Mashhad. The sample data of this study was consisted of 38 extension workers were randomly selected from the study area based on Cochran’s sampling methodology. The research instrument consisted of three parts in Likert scale. The validity of the questionnaire was analyzed and reliability coefficient was calculated for the questionnaire using Cronbach's alpha ratio of 0.745. These amounts showed that questionnaire has an acceptable ability for data gathering. Factor analysis was the major statistical method. The results offactor analysis indicated that socio-economic effective parameters are increasing garden and farm area, increasing qanats water discharge, increasing rangeland area, and preventing lands flood damages. These four factors, in general, had more than 60 percent of the total variance. Final results indicated that watershed management activities have improved qanats water discharge by flood control and aquifer rechrge and increased the area of Agricultural and garden lands. Also, conseving activities in rangelands caused improving of vegetation cover density and the area of rangelands.
Anvar Sanaei; Mohammadali Zare Chahouki; Esmaeil Alizadeh; Omid Asadi Nalivan
Abstract
The aim of this study was to evaluate the effects of grazing intensity around water resources on vegetation characteristics. For arrive this goal, three water points selected in the Silve watershed of Piranshahr rangelands. Around of each water point two regions with 0-150 and 150-300 meter intervals ...
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The aim of this study was to evaluate the effects of grazing intensity around water resources on vegetation characteristics. For arrive this goal, three water points selected in the Silve watershed of Piranshahr rangelands. Around of each water point two regions with 0-150 and 150-300 meter intervals separated. In the four geographical direction and in each distance, a 150 m transect established (total 12 transects), and along of each transect with 15 m intervals a 1 m 2 plot was placed (total 240 plots). Sampling was done with random-systematically method, the list of exist species, canopy coverage, percent of species composition class I, II, III and number of individuals per species were recorded for each plot. Analysis of the data in factorial on the base of complete randomized block design and to calculate diversity, richness and evenness with past software was done. The results showed that there is significant difference (p<0.01) in percentage composition of class I, II, III, annual, perennial plants and total canopy cover. The highest composition percentage and density of the species Br. tomentelus (1.48 and 4.35 respectively) and Fe. ovina (1.12 and 3.44 respectively) was observed. Between water points except annual species composition percentage in the other studied properties there are significant difference (p<0.01). Maximum amount of Shannon wiener and Margalef index there are in second distance of third water point and were 2.18 and 4.10 respectively. The Pielou evenness index was non-uniformly in both distance and three water points.
Mansour Jahantigh
Abstract
Duststorms occur generally in Sistan region. So, it limits the development of the region. Many factors play especial role on duststorms such as removal of vegetation cover due to automobile transportation. The aim of this research was to identify car transportation role in producing dust storm. For this ...
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Duststorms occur generally in Sistan region. So, it limits the development of the region. Many factors play especial role on duststorms such as removal of vegetation cover due to automobile transportation. The aim of this research was to identify car transportation role in producing dust storm. For this reason, three sites with different characteristics were chosen and in each area, two sites of 600 and 300 m length and wide respectively were selected with and without car transportation. Three soil samples were taken randomly from the first, mid and the end of the sites of each location and they were analyzed for pH, EC, CaCO3, organic carbon, moisture, calcium and vegetation cover. The soil erosion measured according to the Universal Soil Loss Equation. The results showed that the car transportation areas have less amount of clay, vegetation cover, topography, soil surface roughness, organic carbon, but, they have an increase in soil small particles with less than 0.84 mm in diameter, pH, EC, CaCo3and land length which they have especial effect on wind erosion of the region. Results also show that the amount of soil erosion is 15.8-216.3 tonsperhectare in study area.
