Zakariya Asadolahi; Mahdi Vafakhah; Seyed Hamidreza Sadeghi
Abstract
Todays, dynamic models are supposed as the most important tools in erosion and sediment phenomenadue to their complexities and existence of many affecting factors. Towards, the present study wasconducted in the Kojour watershed for daily sediment modeling using daily rainfall, discharge andsediment during ...
Read More
Todays, dynamic models are supposed as the most important tools in erosion and sediment phenomenadue to their complexities and existence of many affecting factors. Towards, the present study wasconducted in the Kojour watershed for daily sediment modeling using daily rainfall, discharge andsediment during 2007 to 2010. The modeling process was carried out all data and the monthly andseasonally classification data in linear and nonlinear models. The results indicated that daily linear andnon-linear models did not indicate a suitable model. The monthly and seasonally classification of thedata led to achievement of better models with determination coefficient significant at 5 percent leveland relative error less than 40 percent as compared with those obtained from no classification. It wasalso found out that daily sediment of Kojour watershed was affected by discharge occurred event dayand before four days. The discharge occurred event day is the most effective factor in 80% selectedmodels in the study watershed. The nonlinear models were better estimation than linear models inJuly, September, December and March and autumn but linear models were better than nonlinearmodels in other months and seasons.
Mohammad Reza Sarvati; Kazem Nosrati; Shima Hassanvandi; Babak Mirbagheri
Abstract
Landslides and slope instabilities are major hazards for human activities often causing economiclosses and property damages. Sikan River Basin (Ilam province) due to the topography, tectonic,lithology, and climate has enough potential for occurrence of this phenomenon. The objectives of thisstudy were ...
Read More
Landslides and slope instabilities are major hazards for human activities often causing economiclosses and property damages. Sikan River Basin (Ilam province) due to the topography, tectonic,lithology, and climate has enough potential for occurrence of this phenomenon. The objectives of thisstudy were to determine effective parameters controlling the landslide occurrence and to preparezonation map of landslide risk in Sykan River Basin. In view of this, 11 geophysical characteristicsincluding (height, slop, slop direction), geomorphologic (the slop of land surface), geology (lithology,the distance from the fault), hydrography (the distance from the river), coverage, land use (land useand the distance from road, the distance from village), pedology (soil texture), and dependent variable(landslide distribution) were selected an independent variable and were analyzed using logisticregression model. The results showed that the influential factors on landslides occurrence in the basinare the distance from river, land use, the distance from village, the materials (lithology), slope, and theshape of land surface. Finally, the study area was classified into five major area based on landslideoccurrence risk which 19.1 km2 of total area had very low risk, 15.9 km2 had low risk, 14.9 km2 hadaverage risk and 14.6 km2 had high risk and 9.1 km2 had also very high risk. The model evaluationshowed a high accuracy 74.2% in the study area. The results of this study can be useful for landsliderisk management and for controlling the accelerated parameters.
Shafagh Rastgar; Hossein Barani; Ali Darijani; Vahedberdi Sheikh; Jamshid Ghorbani; Mohammad Ghorbani
Abstract
Vegetation cover as the main factor affecting the water erosion plays an important role in preventingsoil loss. To this end, for better understanding the impact of vegetation cover on soil erosion andsediment yield over the major existing geological formations in the summer rangelands of Balade inthe ...
Read More
Vegetation cover as the main factor affecting the water erosion plays an important role in preventingsoil loss. To this end, for better understanding the impact of vegetation cover on soil erosion andsediment yield over the major existing geological formations in the summer rangelands of Balade inthe Mazandaran province, rainfall simulation studies have been carried out using a portable rainfallsimulator. Among many geological formations across the study area, the three major lithological unitsof mica sandstone, clay and shale sandstone with coal seams of “SHEMSHAK”, structures of tuffshale and dark gray to green shale with volcanic rocks of “KARAJ” and limestone of “LAR” havebeen selected as lowly, moderately and highly resisting formations to degradation. For eachcombination of geological formation and vegetation cover (low, moderate, and high density) threesampling plots of 1x1m have been selected and rainfall simulation has been conducted over them. Foreach plot, the surface characteristics including the vegetation cover, runoff and sediment yield and soiltexture were measured. The measured data were statistically analyzed. Results showed that“SHEMSHAK”, “KARAJ” and “LAR” formations were respectively ranked from highest to lowestwith respect to the volume and weight of sediment yield. Also, there was a strong inverse relationshipbetween vegetation cover percentage and volume of runoff and sediment for all investigatedgeological formations specially in poor vegetation situation that indicate interaction effects betweenvegetation cover and type of geological formations.
Mohammad Ali Zare Chahouki; Lyla Khalsi Ahvazi; Hossein Azarnivand
Abstract
The aim of this study was providing plant species predictive habitat models by using logisticregression method. For this purpose, study area conducted in north east rangelands of Semnanmodeling vegetation data in addition to site condition in formation including topography, and soil wasprepared. sampling ...
Read More
The aim of this study was providing plant species predictive habitat models by using logisticregression method. For this purpose, study area conducted in north east rangelands of Semnanmodeling vegetation data in addition to site condition in formation including topography, and soil wasprepared. sampling was done within each unit of sampling parallel transects and 1 vertical transectwith 750m length, each containing 15 quadrates (according to vegetation variations) were established.Quadrate size was determined for each vegetation type using the minimal area method. Soil sampleswere taken from 0-20 cm and 20-80 cm in starting and ending points of each transect. Logesticregression (LR) techniques were implemented for plant species predictive modeling. To plantpredictive mapping, it is necessary to prepare the maps of all affective factors of models. To mappingsoil characteristics, geostatistical method was used based on obtained predictive models for eachspecies (through LR method). The accuracy of the predicted maps was tested with actual vegetationmaps. In this study, the adequacy of vegetation type mapping was evaluated using kappa statistics.Predictive maps of Astragalus spp. ( κ =0.86), Halocnemum strobilaceum ( κ =0.51), Zygophylumeurypterum ( κ =0.58) and Seidlitzia rosmarrinus ( κ =0.6) with narrow amplitude is as the same ofactual vegetation map prepared for the study area. Predictive model of Artemisia sieberi ( κ =0.33),due to its ability to grow in most parts of north east rangeland of Semnan with relatively differenthabitat condition, is not possible.
Gholamreza Zehtabian; Hassan Khosravi; Ali Azareh
Abstract
Need to Increasing agricultural land in order to improve food resources in the past two centuries recentlead to widespread changes in land use and improper management of these lands. Continue thisprocess can lead to land degradation and desertification, and improve such soils is very costly;Therefore, ...
Read More
Need to Increasing agricultural land in order to improve food resources in the past two centuries recentlead to widespread changes in land use and improper management of these lands. Continue thisprocess can lead to land degradation and desertification, and improve such soils is very costly;Therefore, prevention of land degradation is more desirable. This function requires to research on theutilization of land agricultural and how to use. With this aim, the Khatam city was selected as thestudy region and various maps of the region, including soil, land use and height maps was prepared tohelp ArcGIS9.3 and ENVI software. Four dominant land region mention mono cultivated and multicultivated systems under irrigation, garden lands and range lands as control treatments wereconsidered as the treatments. The soil was sampled and soil factors in two corrective factors, includingcorrection factors N, P, K, CO, Caco3, Mg and damaging factors Hco3, Cl, Na, pH, EC and SAR atdepth 0 to 30 cm of the soil surface horizons were studied. Factors the design of split plots showed thatthere are significant differences between treatments in the region and soil of region is relatively poorfrom CO, N, K and P in soils Rdhy. The comparison of treatment means with Duncan MeanComparison indicated that the garden lands as the most suitable treatments and range lands as the mostunsuitable one.
Tahereh Sadeghi Shahrakht; Mohammad Jankju; Mansour Mesdaghi
Abstract
Rangeland shrubs may provide mechanical facilitation on their understory plants, by protecting themagainst the livestock grazing. However, such a facilitation effect may vary depending on the rangelandutilization rate. In a field research, mechanical facilitation of rangeland shrubs was compared in ahighly ...
Read More
Rangeland shrubs may provide mechanical facilitation on their understory plants, by protecting themagainst the livestock grazing. However, such a facilitation effect may vary depending on the rangelandutilization rate. In a field research, mechanical facilitation of rangeland shrubs was compared in ahighly grazed, a moderately grazed and an enclosure site; in an arid rangeland, Kakhak, Gonabad,Iran, during spring to summer 2011. Twenty line transects were established in various directions andslope aspects. Forage production was measured by clipping method within the paired plots, i.e. underthe canopy of nursing shrubs and their nearby open areas. In the enclosure site, forage production wassimilar under the canopy of shrubs and in open areas, whereas in the highly and moderately grazedsites there were more forage under the canopies. These results indicate increases in mechanicalfacilitation of rangeland shrubs by increasing the grazing intensity. The mechanical facilitation wasalso varied depending on the life forms of understory species. In the enclosure, the greatest facilitationwas on annual forbs, whereas in the highly grazed site it was on perennial grasses. Results of thisstudy show important role of rangeland shrubs on preserving understory forage plant against theintense livestock grazing.
Fariba Alavizadeh; Kamalledin Naseri; Ali Golkarian; Ali Tavili
Abstract
Soil erosion is a main hazard in most area of the country specially in arid and semi-arid regions and itis very important because of sedimentation, pollution, increased flooding and its negative effects onsoil productivity. One of the features of arid and semi-arid areas is the presence of low cover ...
Read More
Soil erosion is a main hazard in most area of the country specially in arid and semi-arid regions and itis very important because of sedimentation, pollution, increased flooding and its negative effects onsoil productivity. One of the features of arid and semi-arid areas is the presence of low cover ofvascular plants. These empty spaces are usually good niches for biological soil crusts or cryptogamslike mosses. These crusts contribute to a variety of ecological functions and have different effects onsoil features and vascular plants. The present study was carried out in the rangelands of Torogh dambasin of Khorasan- Razavi province in order to find the effects of such kind of plants (mosses) onwater erosion. For this purpose, artificial runoff streams in plots with two intensity (low and high) for30 minutes. In order to study the effects of different amount of mosses on sedimentation and specificerosion, four different density of mosses in the same experimental situation were studied: high (60-75% of plot), medium (35-50% of plot), low (10-20% of plot) and control (0%). The results ofanalysis of variance and tukey method by the use of Minitab software showed a significant differencein 95% level between the four considered density of mosses and the two intensity of water. As mossesdensity decrease, sedimentation and specific erosion increased consequently. But there were nosignificant differences in infiltration between the different treatments.
Zohreh Alijani; Fereydoun Sarmadian; Seyed Rouhollah Mousavi
Abstract
Today, extensive improvements in fields of soil mapping have increased the purity and accuracy ofsoil maps. Usual mapping methods moreover depend on skills and experience of surveyor inidentifying and delineating the boundaries, also need the high cost and time consuming that face thesoil mapping with ...
Read More
Today, extensive improvements in fields of soil mapping have increased the purity and accuracy ofsoil maps. Usual mapping methods moreover depend on skills and experience of surveyor inidentifying and delineating the boundaries, also need the high cost and time consuming that face thesoil mapping with restrictions. In this study, aerial photographs with 1/40000 scale were used in orderto preparation of the initial interpretive map and determination of sample region. Then, the numbers of24 profiles were described in determined units. After sampling and necessary physicochemical tests,soil map of Kouhin (Qazvin) was prepared and accuracy of map was calculated in two methods in alllevels of taxonomy. The first method was formation of error matrix and calculation of kappa index andsecond was comparison the geopedological map with described profiles and evaluation the results ofeach. Then a part of a geopedological map that had overlapping with map prepared by usual methodwas compared with this map. Results showed the overall accuracy of 67.5, 90.5 and 98.5 percent inlevels of family- subgroup and great group- suborder and order of soil for geopedological methodrespectively.
Javad Motamedi; Esmaeil Sheidai Karkaj
Abstract
Species diversity is one of the important characteristics shows rangeland ecosystems changes, which isalready under effects of management practices. Thus, this research was conducted to study speciesdiversity variation and assess suitable distributive abundance model in three rangeland sites in WestAzerbaijan. ...
Read More
Species diversity is one of the important characteristics shows rangeland ecosystems changes, which isalready under effects of management practices. Thus, this research was conducted to study speciesdiversity variation and assess suitable distributive abundance model in three rangeland sites in WestAzerbaijan. These sites were almost similar in environmental properties and differ in view point ofgrazing intensity (light, moderate and heavy intensities). After selecting sampling areas in each of thesites, species cover were recorded in 60, one square meter quadrates with 10 meter far from each otherwhich established along 100 meter transects in sites and then richness, evenness and diversity(heterogeneity) indices were calculated. Thus, rank-abundance curves were plotted and fourdistribution models such as log-normal, geometric, log-series and Brocken stick were fitted to each ofthese sites and then best model was selected in 0.05 level of confidence. Means comparison testshowed that richness, evenness and heterogeneity indices have significant differences (P<0.01) insites. Highest diversity is observed in the light grazing intensity site and lowest diversity is in heavygrazing intensity site. Species rank-abundance curves point out that low-abundance species are seenlower in light grazing site and its curve have gentler slope than moderate and high grazing intensitysites thus its diversity is higher. There is lowest species number in high grazing intensity site andevenness is lowest too due to its high number of rare and dominant species. Log-normal model wasfitted to light site implying on sustainable community and high grazing intensity site is fitted withgeometric model which point out on distractive communities with low diversity. Overall resultsshowed that implementing light grazing can protect species diversity and heavy intensity declinesspecies diversity that this shows the need considering of management on implementing light grazingintensity in the rangeland.
Aliakbar Nazari Samani; Fatemeh Avazadeh Tavakoli; Hassan Ahmadi; Gholamreza Rahi
Abstract
Gully erosion is one of the most destructive types of channeled water erosion that removes aconsiderable volume of soil as it develops. This type of erosion consists of complex a geomorphicprocess that has been known as an indicator of accelerated soil erosion. In this research theadvancement of 25 headcuts ...
Read More
Gully erosion is one of the most destructive types of channeled water erosion that removes aconsiderable volume of soil as it develops. This type of erosion consists of complex a geomorphicprocess that has been known as an indicator of accelerated soil erosion. In this research theadvancement of 25 headcuts were assessed through digital interpretation of multi-temporal aerialphotos, field observations and GIS data analysis over the two periods of 1967-1995 and 1995-2008.Moreover, the stepwise regression analysis procedure was applied to extract the effective factors ongully head advancement (such as topography, physico-chemical soil attributes and morphology ofgully). The results indicated that the mean of gully head advancement over the periods of 1967-1995,1995-2008 and the mean of two periods were measured 1.36, 1.23 and 1.3 m/y, respectively. Further,regression analysis revealed that headcut's contribution area, distance of gully-head to ridge, height ofgully head cut and SAR are the main factors on gully head advancement. Therefore, distance to ridge,headcut high and presence of plunge pool could use as suitable criteria to distinguish the active gulliesin order to prioritizing the conservation activities.
Arash Malekian; Mahrou Dehbozorgi; Amir Houshang Ehsani; Amir Reza Keshtkar
Abstract
Consecutive droughts in Sistan and Baloochestan province cause water resources restriction and this isa very significant problem for this region. In this study, in order to forecast the drought cycle in 9climatological stations in the province, we used Artificial Neural Networks. The input data wereaverage ...
Read More
Consecutive droughts in Sistan and Baloochestan province cause water resources restriction and this isa very significant problem for this region. In this study, in order to forecast the drought cycle in 9climatological stations in the province, we used Artificial Neural Networks. The input data wereaverage of annual rainfall data in all stations and also deciles precipitation index, which the first 30years from 1971 to 2000 used for training the network and the last 8 years from 2001 to 2008 forsimulating it. The network consists of Multilayer Perceptron (MLP) and Back Propagation Algorithm(BP) and also sigmoid transfer function. Number of Neurons in hidden layer was 10 with 1-10-1structure and was calculated based on the lowest RMSE. Then drought prediction was done in neuralnetwork with the trained algorithm and without using actual and observed data in 2009 to 2012.Results showed that, the network was able to simulate and forecast DPI index with 97% regressionand average RMSE error less than 5%. According to drought indices, results showed that the droughtwill have an increasing trend in all stations in this region in 2009 to 2011. Therefore, by using thismethod, drought can be predicted in later years without any need to have actual meteorological dataand also can be used in water resources management, drought management and climate changes.
Mahdi Ghorbani; Mahrou Dehbozorgi
Abstract
Nowadays, a lot of natural resource co-management plans due to lack of attention to stakeholders’characteristics and position in network of social relationships have failed. Actors or key personnel’srecognition has been one of administrative requirement of natural resources co-management ...
Read More
Nowadays, a lot of natural resource co-management plans due to lack of attention to stakeholders’characteristics and position in network of social relationships have failed. Actors or key personnel’srecognition has been one of administrative requirement of natural resources co-management plans.The most influential actors in environmental decisions making can be identified based on stakeholdersand network analysis. This study is aimed to determine the social powers based on network analysisapproach and stakeholders analysis at the local users level of common rangeland of Nariyan village inTaleghan region. In this study, first, Rangeland users were identified based on survey methods thentrust and cooperation matrixes are produced and then degree centralities index and betweennesscentrality were computed by questionnaire finally each actor’s topology has shown in the network.The result of this research is effective in identifying actors with central position that perform a keyrole in Nariyan rangeland co-management plan. Also, the result of this study can assist naturalresource managers and planers in identifying social powers in order to organize and implement thesustainable landscape management plans.
