University of Hormozgan
Environmental Erosion Research Journal
2251-7812
6
1
2016
6
1
Comparing the Analytic Hierarchy Process (AHP) and fuzzy logic for zoning the risk of gully erosion in the three regions of the Ardebil province
1
16
FA
hosein
shahab arkhazloo
ferdowsi university of mashhad
hojat
emami
ferdowsi university of mashhad
gholam hosein
Haghnia
ferdowsi university of mashhad
abbazar
Esmali
university of Mohaghegh Ardabili
Gully erosion is the most advanced water erosion in watersheds that produce large volumes of sediment can cause serious damage. In order to manage and cope with this type of erosion, to identify areas of high risk of gully erosion in the watershed is very important. For this purpose gully erosion hazard zonation maps by combining information layers of different factors affecting the formation of gullies is prepared on the basis of their importance. Analytic hierarchy process (AHP) and fuzzy Gamma operator new and useful methods for weighting and combining various layers of information. This study aimed to compare two methods of zoning with AHP and fuzzy gamma 0.8 in three watersheds in the name of Orta dagh, Molla ahmd and Sarcham was conducted in Ardabil province. For zoning from eight factor include slope, aspect, elevation, land use, Plant cover, geology, distance from roads and distance from waterways that are important factors affecting the formation of gullies were used. For comparison of two methods to accurately determine the zoning of the area, two compression density ratios (Dr) and quality sum (Qs) was used. The results showed that in all three areas fuzzy method is more accurate, AHP method are careful in the two Orta dagh and molla ahmad area but in sarcham did not workable. In general for zoning of gully erosion risk using fuzzy gamma was suitable. However, if selection and weighting factors influenced the formation of gullies has careful, AHP can was a good method.
University of Hormozgan
Environmental Erosion Research Journal
2251-7812
6
1
2016
6
1
Understanding rill erosion rate in dry-wet condition
17
29
FA
S.
Mohamadpour
H.
Rouhani
H.
Ghorbani Vaghei
S. M.
Seyedian
Rill erosion is considered to be the most important process affecting soils created by the concentrated flow of water. In this research to quantify sediment transport and runoff in natural rills, two rill experiments under dry and wet conditions were accomplished in November 2013 in the Golestan Dam. Filed experiments lead to a closer understanding of the dynamics and power of different soil erosion processes in a rill channel. Water is introduced with an intensity of 12 L min−1 into a rill within 10 min. Rill cross sections, slope values, flow velocities and sediment concentrations were measured for each rill at three points every 5, 10 and 16 m from the origin along a rill. The flow velocity within the rill was measured by recording the travel times of the waterfront and of two applied colour tracers .The results showed that the flow velocity in the under wet condition is higher than dry condition. Under dry condition, the highest sediment concentrations are recorded at the initial runoff flow despite lowest flow velocity. The initial high sediment concentration may be attributed to the existence of a thin loose surface layer. Flow velocity increases along the length of the channel towards an increase with flow duration. However suspended sediment concentration measured tend to decline with decreasing the sediment-transport capacity. Temporal variations in the sediment concentrations indicated that changes Sediment concentration at the time of the creation of the nought erosion process with inflow water in the experiments and sediment transport mostly attributed to the bulldozer effect. Also showed that hydrological response and sediment production were significantly different in two rill channels which only ground cover were significantly different
University of Hormozgan
Environmental Erosion Research Journal
2251-7812
6
1
2016
6
1
Assessing the effective factors on water erosion in Marly deposits of Mishan and Aghajary formations in the west of Bandar Abbas
30
51
FA
simin
makki
Hormozgan University
peiman
rezaee
Hormozgan University
Hamid Reza
peyrowan
soil conservation and watershed management institute
By knowing of the effective parameters on erodibility of marl deposits, can be improve landuse and reduce erosion and sediment yield. At present research, Assessing the effective factors on water erosion in the marly area, Mishan and Aghajari formations in the west of Bandar Abbas, is studied. For this purpose, according to lithology map, general slope and landuse, determine the sampling points and using a portable rainfall simulator type kamphorst in the desert, the runoff and sediment yield were studied. 18 test of rainfall with intensity 6/74 mm per minute on the Sampling points, with at least 3 replications in Mishan and Aghajari marl units in the west of Bandar Abbas at slopes 10 and 20 Degree in both surface and gully erosion was conducted and 18 samples of runoff and sediment were taken. 18 sediment samples were collected for physical and chemical analysis All of which were analyzed for granulometry. Chemical properties include determining the parameters of electrical conductivity (EC), degree of acidity (pH), organic matter (OC), cations and anions solution, sodium absorption ratio (SAR), lime, gypsum and exchange capacity cation (CEC). Atterberg limits of 6 sample was measured. The results showed that in both Mishan and Aghajari formations, the mud content of the samples in surface erosion is more than gully erosion shape. In surface erosion shape, Mishan marl has silt and clay particles more than Aghajari marl, therefore Mishan marl is more than résistance to erosion and produce less sediment. Based on rainfall tests in marly area, inherent erosion of marls of Mishan and Aghajari are 2/76 and 5/27 respectively compare to tolerance erosion rate. In this study, for the first time, the ratio of sand content to sum of clay and silt content as standard physical indicators for the separation of two surface and gully erosion forms was presented from each other. Above mentioned index in Marls with gully erosion is more than which with surface erosion forms. The liquefaction potential study subjects showed that the samples with liquefaction capacity, the gully erosion development.
University of Hormozgan
Environmental Erosion Research Journal
2251-7812
6
1
2016
6
1
Evaluation of Univariate, Multivariate and Combined Time Series Model to Prediction and Estimation the Mean Annual Sediment (Case Study: Sistan River)
52
70
FA
Mohammad
Nazeri Tahroudi
Urmia Uni
Keivan
Khalili
Urmia Uni
Marziyeh
Abbaszadeh Afshar
Urmia Uni
Zahra
Nazeri Tahroudi
Kashan Uni
Farshad
Ahmadi
Ahwaz Uni
Mehdi
Motallebian
Urmia Uni
Erosion, sediment transport and sediment estimate phenomenon with their damage in rivers is a one of the most importance point in river engineering. Correctly modeling and prediction of this parameter with involving the river flow discharge can be most useful in life of hydraulic structures and drainage networks. In fact, using the multivariate models and involving the effective other parameters such as flow discharge can be improved the modeling and prediction results. In this study using the common time series model (ARMA), multivariate model (CARMA) and combined models (ARMA-ARCH and CARMA-ARCH), mean annual sediment (ton.day) and mean annual flow discharge (m3/s) time series of Sistan River in period of 42 years (1970-2012) to estimating and prediction the mean annual sediment. By using the mentioned models, mean annual sediment in period of 1970-2012 was modeled. The results showed that with involving the mean annual flow discharge in multivariate model, the accuracy and model's error in validation phase compared the univariate models were improved almost of 8 and 50 percentages respectively. Also the results showed that among four mentioned models, the combined multivariate model have a lowest error. By using the multivariate model, the time series of mean annual sediment until the end of 2022 year were predicted. The prediction results showed that the mean annual sediment in prediction period was decreased compared the previous years.
University of Hormozgan
Environmental Erosion Research Journal
2251-7812
6
1
2016
6
1
Statistical and synoptic analysis of erosive wind in North-West of Iran
71
87
FA
Bromand
Salahi
University of Mohaghegh Ardabili
The occurrence of erosive winds in the North West of Iran always causes damage to urban facilities and agricultural fields. By identifying behavior and synoptic patterns of Strong winds, necessary strategies can be chosen to deal with this destructive phenomenon. In this study, the fastest erosive winds and its steadiness coefficient were analyzed in selected stations of North West of Iran. Suitable model was introduced to predict these winds by using descriptive statistics analysis and logarithmic and order 6 polynomial trend. To understand the synoptic reasons for the occurrence of erosive winds in study area, 500hPa geopotential height, wind vector and sea level pressure maps were interpreted for the days with occurrence of erosive winds. Statistical analysis showed that the distribution of wind speed data follows from two-parameter Weibull and normal distributions. The results of the logarithmic and order 6 polynomial trend of data also indicate increase trend in erosive winds in Ardabil and Zanjan stations and decrease trend in wind steadiness coefficient at all stations. Synoptic analysis also showed that the erosive winds in stations under study were related to pressure gradient at sea level, the establishment of a relatively deep through and the polar front jet stream in 500hPa level.
University of Hormozgan
Environmental Erosion Research Journal
2251-7812
6
1
2016
6
1
Effects of Runoff and Sediment from Upland Catchment on Mangrove Forests Area (Case Study: Gabric-Hormozgan)
88
102
FA
A.
Bazrafshan
S.
Ahmadi
A.
Khoorani
The aim of this research is exploring the impact of changes in runoff and sediment of the upstream catchment on the changes in the area and amount of canopy in Gabric-Jask mangrove. Hence, hydro-climatological parameters including amount of precipitation, discharge, and sediment in Gabric catchment during the statistical period of 1993 to 2010 were selected and the annual standardized index related to each parameter respectively including SRI, SPI, and SSI were calculated. Also, satellite images of Landsat of TM and ETM+ sensors were used in order to explore the changes in the canopy by the use of NDVI and the area was prepared and its calculations were done. Cross correlation function and moving average of 3, 5, and 7 years were used to explore the relation between hydro-climatologic factors and the area and canopy of mangrove. Based on the results related to the canopy changes there was two increasing periods and one decreasing period and the area changes had an increasing trend during the study statistical period. Results of exploring the relation between incoming precipitation, discharge, and sediment to the mangrove forests show that NDVI changes and the area of mangrove forests have a significant relationship with three years moving average of SPI, SRI, and SSI indices with the correlation coefficients of 0.6, 0.8, and 0.56, respectively. Finally, results showed an increase in the rate of NDVI index with an amount of 0.33 and an increase in the area of Gabric-Jask mangrove forests with an amount of 0.22 ha/year.