جستجوی مقالات مرتبط با کلیدواژه « تغییر کاربری » در نشریات گروه « آبخیزداری، بیابان، محیط زیست، مرتع »

Changing the use of natural ecosystems, including dam construction and also the conversion of pasture land to agricultural land, can cause irreparable damage to different parts of the ecosystem. Based on the research results the most destructive of them is the reduction of vegetation, the increase of erosion and also the reduction of biodiversity. In the management of natural ecosystems, monitoring vegetation changes is very important. The present research was carried out with the aim of investigating the changes in the vegetation cover indices and species diversity in the plowed and abandoned agricultural lands and the natural cover of the pastures around the Yan Chashmeh underground dam located in Ben city of Chaharmahal and Bakhtiari province.

To carry out this research, four sites including natural pastures around the dam, lands upstream of the dam (rain fields under cultivation), lands where the dam reservoir is being built (plowed and abandoned for less than 7 years) and lands downstream of cedars have been planted for more than 15 years) were selected and in each of the sites, three transects with a length of 50 meters parallel to each other and perpendicular to the slope of the area were established at a distance of 50 meters from each other. 15 plots of 2 x 2 square meters were placed on the transects with a distance of ten meters from each other. And then, in each plot, the percentage of canopy cover, biomass, percentage density of leaf litter and bare soil were recorded. The theoretical estimation method was used to determine the level of plant canopy in the plots. The biomass of the species was determined using the cutting and weighing method. In order to check species diversity, Simpson and Shannon-Wiener indices and to compare species richness, Margalf and Menhinik indices were calculated in Past software. Determining the condition of the pasture was done using two modified four-factor and six-factor methods.

 The results showed that plowing and changing the use of pasture land to agricultural land has caused a significant reduction in the crown cover and, as a result, a decrease in the amount of biomass density, and also a decrease in diversity and species richness in the plowed and abandoned lands compared to the sloping pastures of the region. The results showed that in addition to reducing the cover, plowing has caused a change in the species composition and an increase in annual and invasive species and a decrease in shrub species. According to the results of the change of pasture use, the surrounding pastures decreased from average to weak and very weak condition in plowed and cultivated pastures (upstream) with a negative trend.

The measures taken to build the dam and then the expansion of agriculture have caused plowing and soil manipulation in the region. Besides, it is possible that in the long term, abandoning agriculture due to the drop in the water level of the underground dam will cause more soil erosion. Therefore, it is necessary to continuously monitor the vegetation changes in the are

Land use changes are one of the important factors in changing the hydrological status of the watershed and soil erosion, so the type of land use is one of the important and determining factors in the production of surface runoff. By knowing the process of land use changes, it is possible to manage the effects of land use changes in the hydrology of the affected areas and led the natural ecosystems towards balance. The following research was carried out with the aim of revealing land use changes using satellite data and analyzing its role in changing the hydrological situation.

The study area is the upstream part of the Siahroud river basin located in the south of Qaemshahr city. In this research, to extract land use maps of different time periods, integrated pixel-based and object-oriented methods, unsupervised and supervised classification of TM sensor images of Landsat 5 satellite related to 1998 and 2009 and OLI sensor images of Landsat 8 satellite related to 2015 and 2019 were used. After preparing the land use maps for each time period, the CN values for each land use were determined based on the standard instructions of the SCS method and the weighted average CN was estimated for the entire study area. At the end, the amounts of runoff production and depth of runoff resulting from rainfall are calculated.

The land use changes of the studied area in the period of 22 years showed that 281%, equivalent to 657 hectares, was added to the area of citrus orchards. About 5% of the area of deciduous forest has decreased and the area of residential areas has increased by 57%. Due to the changes in land use during this 22-year period, the weighted average value of CN has decreased from 63.01 to 62.73. Also, the estimation of the amount of runoff for rainfall equal to 59.8 mm (average maximum rainfall of 24 hours during the period of 22 years) showed that the depth of runoff has decreased from 4.83 mm in the 1988 situation to 4.73 mm in the condition of 2019.

Considering the changes in land use and its effect on watershed runoff production, it seems that these effects have been moderated and land use changes have played a role in reducing runoff production over a period of 22 years. Therefore, it is expected that with the continuation of this process of land use changes, the production of runoff in the upstream of the Siahroud River watershed will decrease.

In Iran, as in other countries, social and economic factors have led to land use changes depending on regional conditions. The Taleghan watershed, due to its proximity to population centers such as Tehran and Karaj, construction of the Taleghan Dam in 2001, and becoming a tourist center, has undergone significant changes. Many studies have been conducted to evaluate land use changes in this area, but these studies have investigated changes only until the time of dam water withdrawal in 2005 or until 2016 at most. Thus, this research investigates and analyzes land use changes in the Taleghan watershed over a period of thirty years (1987-2017).

The study focuses on land use changes in the middle Taleghan watershed. A land use map was prepared for the last thirty years (1987, 1998, 2008, and 2017) using Landsat satellite imagery. The hybrid classification method (a combination of supervised and unsupervised methods) was used, and accuracy was measured using Kappa and overall accuracy, yielding acceptable results in percentages. The T index was used to calculate land use changes.

The study shows that the abandoned dryland area (12.08%) is the largest after pasture land use (71.06%). The area of villa construction increased, while the garden area decreased over the thirty-year period. The T index calculation reveals that barelands experienced the most changes during the thirty-year period.

Spatial patterns of land use changes were estimated using spatial statistics and the calculation of the share of changes in various land uses. Location quotients were used to analyze the data, and it was calculated for the land uses that experienced the most changes in each sub-watershed in 1987, 1998, 2008, and 2017. The results of the LQ show that the rangeland area was almost constant during the period of 1987-2017. The areas of irrigated and rainfed agriculture fluctuated due to emigration and immigration during this period. The area of residential land also increased significantly due to the construction of villas and promenades around the lake by indigenous and non-indigenous people. Investigating the variations of the spatial pattern of different land uses revealed that the most changes occurred in the sub-watershed around the dam lake and the main river.

Gully erosion contributes severe land degradation. It is therefore, necessary to identify the aggravating factors and to provide for sensitive areas to gully development. The aim of this study was to determine the spatial and climatic distribution of gully in Kermanshah Province, Iran and to identify the morphological characteristics and the main factors of their development. First, using 1: 20,000 and 1: 50,000 aerial photographs, the predominantly gully areas of the province were identified and then this information was corrected using field suevey. The climatic zones of the gully areas are identified using existing maps and modified by the Domarten Method. In each climate, one to three gully areas were identified as targets and in each of them a gully was identified and two replications were identified. The gully chanel chrectreristices were location, landuse, dimensions at the head-cut, intervals of 25, 50 and 75%, slope, width, length and cross section. The results showed that 17% of areas in the Kermanshah Province was affecterd by gully erosion comprising eight sub-climate classes. Dominat topographic conditions of gullies were developed at hilly and gentle plain areas with Trapezoidal cross section. The cross section indicated deep and V-shaped gully in marl formations (Fars group). These areas included Sarfiroozabad, Somar and Jabbarabad where most of gully measures were deeper and wider than other parts. Among the effective factors in creating and expanding the gully, we can mention heavy rainfall, slope, soil erodibility and destruction of vegetation upstream of the basin as natural factors and change of land use and improper exploitation as human factors in developing gully erosion.

The soil of rangelands in mountainous areas has always been considered for changing to agricultural land due to its abundant organic matter. Research shows that changing the rangelands and implementing agricultural operations can increase soil erosion and generation of runoff. Therefore, using all kinds of modifiers as a suitable and desirable solution can control soil loss in these lands. This study was conducted with the aim of investigating and comparing the effect of land use change in rangeland and the effect of organic amendments on reducing sediment production, runoff and soil loss in one of the subbasins of Mereg river.

The present research was conducted in one of the sub-basins of Merg river, five kilometers away in Kermanshah province. This area is one of the main branches of the Karkhe River and one of the most important subbasin of the Qaresou River. The average annual rainfall is 458.59 mm and the average annual temperature is 13.89°C. Investigating the effect of land use change and organic modifiers (sheep manure and waste compost) on generation of sediment, runoff and carbon loss in both rangeland and agricultural uses, at erosion plots in dimensions of one in two square meters for two years (1398 and 1399) were evaluated. In the first year, samples were collected from undisturbed erosion plots, but in the second year, two modifiers (sheep manure and municipal waste compost) were added to agricultural plots in the amount of 1.5 kg. The modifiers were added  at the ended of July and until the first rain of the autumn season, there was enough time for chemical interactions and influence on the soil characteristics .The samples of runoff and sediment as well as soil samples were analyzed in the laboratory and the volume of runoff, the amount of suspended sediment, the organic carbon percentage of the sediments and the physical and chemical characteristics of the soil were measured.

The texture of the soil in both land use was the same (clay loam). But in terms of the amount of organic carbon, the two land uses have a significant difference (at 95 percent level) and this parameter is more than twice as much in the rangeland as in the agricultural use. Based on the results in the first year of sampling, the values ​​of runoff volume, sediment weight, carbon loss during five rainfall events in agricultural were 83, 90 and 87% higher than rangeland. In the second year of sampling, plots located on agricultural lands were treated with soil conditioners and their impact was investigated. Although the use of soil conditioners reduced runoff by 20% and reduced the amount and concentration of sediment in agricultural lands about 31.68 and 13.13%, but the amount of these parameters is still 67, 95, and 72% lower in rangeland use, respectively. The results also showed a 71% higher organic carbon loss in agricultural land use than rangeland. The results of this research showed that the modified wars were successful in reducing soil and water loss, and sheep manure treatment worked better than compost in controlling runoff and sediment.

In general, the results of this research showed that the amendments were able to reduce water and soil loss and sheep manure treatment worked better than compost in controlling runoff and sediment. But none of them have been able to reduce the effect of tillage destruction on this slope as much as rangeland. This shows the role and importance of protecting rangeland in reducing soil degradation and water wastage

The aim of this study was to evaluate the impact of forest on erosion and runoff variables and compare it with rangeland and agricultural in part of Mereg watershed located in Kermanshah province. At first, three forest mass were identified and divided into three density categories (low, medium and Many), then Soil and hydrological parameters were measured in each forest density area and also in both agricultural and rangeland using a rainfall simulator. Rainfall was run at a rate of 83 mm / h for 24 minutes with 18 repetitions. The hydrological results in forest mass showed that the mass 2 (with medium density) produced 32.6 percent more runoff than the first stand and 33.5 percent more than the third Mass, which could be due to the soil repellency in forest, but no statistically significant difference was observed in other variables. Also, the comparison of the hydrological variables in three land uses (forest, rangeland and agriculture) showed that although the runoff from forest was 61.5 percent more than rangeland and 54.2 percent more than agricultural, however, the amount of sediment output from these plots was 62 percent less than rangeland and 91percent less than agricultural. This decrease in rangeland compared to agriculture was 76.26 percent.

Land use change is a major challenge to agricultural production that has intensified in recent years. The problem will in the long run have severe economic, social, and environmental repercussions for rural areas and beyond. Identification of the many factors involved allows for effective policies to be formulated and executed in order to reduce the adverse impacts. It is the purpose of this qualitative study to analyze the factors affecting agricultural land use change in Bavi County, Khuzestan. The statistical population used in this study comprises local farmers who committed either authorized or unauthorized land use changes. Sampling is accomplished using the ’snowball’ method and data are collected through interviews with users. Analysis of the data thus collected reveals that economic, social, legal, and regulatory factors as well as indiscriminate spatial development may be identified as the causes underlying agricultural lands use changes. Based on the results obtained, recommendations are finally formulated to improve upon the current indiscriminate land use change in the study area.

Soil seed bank has an important role in vegetation restoration following cessation of disturbance. In this study, the soil seed bank richness and diversity were investigated in semi-steppic rangeland with a history of land conversion into cultivation in Charmahal-Bakhtiari province. Land-use changes were identified in grassland and shrubland and then were classified into four groups according to the time since abandonment including < 5, 5-15, 15-25 and > 25 years. Aspect was considered in each group. Soil was sampled and seed bank was identified using seedling germination method in glasshouse. Then, seed bank richness and diversity indices were calculated. Results showed that in seed bank the number of perrenilas was greater than annuals. In both grassland and shrubland time since abandonment significantly influenced the soil seed bank richness and diversity. In grassland soil seed bank richness and diversity decreased with time of abandonment but in area with more than 25 yrs of abandonment seed abnk richness and diversity significantly increased. Aspect significantly affected both seed bank richness and diversity in shrubland. North slpoe showed fluctuation in seed bank richness and diversity during abandonment while an increase was found in west slope and a reduction in south and east slopes. In both sites the soil seed bank indices significantly increased shortly after abandonment (<5 yrs) but seed bank richness and diversity showed resilient in >25 yrs in grassland and >15 yrs in shrubland.

Environmental protection and natural resource conservation aimed at ensuring food security through healthy, organic food production form major items of Iran's development plans. The involvement of too many public agencies and authoritative sources has over recent years led to legal challenges hindering the realization of development and economic goals. This situation has, in turn, caused the Farm and Garden Land Conservation Act to face not only legal challenges in its implementation but, in certain cases, to conflicts with other laws. Despite its amendment in 2006, the law still requires substantial modifications and radical revisions in such areas as punitive measures for violation of law or methods to restore degraded or encroached land, and selection of trustees to carry out legal verdicts when they are approved for implementation. The present descriptive-analytical study explores the legal challenges facing the above Act and the duplicate roles and interventions by multiple government bodies. It is maintained that, as an attempt to resolve the mentioned challenges, conflicts, and parallel work, it is necessary to adopt a new approach that integrates the highly dispersed and diverse laws into a unit hole and one that grants authority to an independent institution or agency to make decisions about and to carry out law enforcement outside the urban and rural legislative units. These provisions are expected to reduce illegal land use changes and to witness proper law enforcement across the state.

The method employed in this study was based on experimental research and field study. In this method, the stored radiocesium of the forest region which was supposed to be converted into Poplar plantation has been compared with the stored radiocesium of the reference region. 11 core samples were taken from reference region and then 7 core samples were selected from the transect which was a part of Poplar plantation that were taken by topographic characteristics in a depth of 25 centimeters, Having prepared the core samples according to the IAEA, they were packaged into the special Gama spectrometer containers. After that the amount of radiocesium of all samples has been measured by Bq kg-1 scale. The findings revealed that the amount of radiocesium in reference region was computed as 5894.1. Bq m-2 y-1. In the present study, soil loss rate during transect was estimated using proportional conversion models and mass balance I and II of 18.70, 22.72 and 18.64 ton / ha, respectively. These values were obtained for slope of 10-20%, canopy cover of 25% and clay loam soil under 1000 mm precipitation. This study recommended mass balance model II for estimation of erosion in changed land use areas and concluded that forest land use change to plantation due to reduction of long soil cover and plantation management by removing other seedlings and herbaceous cover increased the rate of soil erosion occurs. This process for many years has caused the erosion rate to exceed and has caused the loss of 0.1 cm of soil per year.

Rivers are eco-hydrological dynamic systems contribute to agriculture, industry and tourism activities as well as environmental sustainable. However, rivers and their flow are impacted and contaminated through landuse change, urban sludge, agricultural waste, reservoir dam building and drought impacts. The objective of this research was to assess factors affecting the catchment landuse change and riverside plant removal seven different reaches of Dinavar river (upper sub-catchment of Karkheh basin), Kermanshah province, Iran during 2016-18. The results explored that due to dominant clay and silt deposits of Quaternary in the plain areas, meander and riparian are the dominant morphology in four reaches improper sand and gravel harvesting and converting river bank and its groves (willow and spruce) to arable lands cause development of Tamarix. Sp and some unpalatable plant species in the river bed and furthermore river bank erosion. In these reaches, the river is contaminated by disposal of rubbish, plastic, animal manure and agricultural waste. In upper River branched, severe soil disturbance through improper civil activities, road construction and up-down the slope tillage practice attributed in considerable siltation phenomenon which quickly delivered to river system by runoff during rainfall occurrence. The upper reach (upper Jamishan Dam that was built in 2018) urban and industrial wastes are main river water pollutant sources. It is concluded that the Dinavar river morphology is changed and its water also is contaminated through improper tillage practice (up to down slope), landuse change, improper civil activities, local tourism as well as waste, and rabbles disposal that are being accelerated.

Conservation of agricultural land use as the basis for agricultural activities is a most important decision-making component in both national and agricultural development schemes. This is because current and future food security in all communities, whether small or large, relies heavily on the conservation and protection of existing agricultural lands to ensure sustained and effective production. Hence, optimal land utilization and protection to guarantee human survival on earth is an important responsibility of policy makers and sustainable development planners. Governments in the Eastern Block have been mandated to develop plans as their priority agenda for prohibiting land use change and land fragmentation in order to secure consolidated land farms with enhanced productivity via optimized use of land. In these countries, large allocations are dedicated annually to the execution of such plans in order to protect their farms and agricultural production. The present study aims to survey the experiences gained in Iran and some Asian countries in enforcing the pertinent laws and executing schemes in the field of land use management in order to gain an insight that can be exploited toward developing the relevant measures for improving the present conditions in Iran and to achieve a desirable land use management system.

Banketing and artificial afforestation are effective processes for soil carbon storage and removal of carbon from the atmosphere. In this research, land use change and its effects on carbon storage has been studied in Pakal Basin in Markazi Province. Rangeland was selected as a witness for comparing soil carbon storage with areas with banketing operations and planted with almonds (biomechanical activity) . Soil was sampled on transect and plot in systematic random samplingFor this purpose, three plots were used randomly, along each transect. Soil samples of one kilogram were taken from 0-15 and 15-30 cm depth of each plot. . Soil physico-chemical properties such as bulk density, organic carbon and soil texture were analyzed. Resalts showed that total carbon stored in the soils of bio-mechanical operation is 33.65 t.ha-1 from which 30% belongs to above and underground biomass, 2% litter,38.9% in the depth of 0-30 and 29.1% in the depth of 15-30 cm. Also, the the results showed theamount of soil organic carbon of 30.16 t.ha-1 in witness area from which 4% belongs to above and underground biomass, 3% litter, 62% in the depth of 0-15 and 31% in the depth of 15-30 cm.. As a result, biomechanical operations are more effective in carbon sequestration compared to rangelands as witness areas.

This study aimed to effect of converting rangeland to afforestation on carbon and nitrogen storage was done in forested areas of Hassan Abad in Sanandaj. Masses of studied was include Cupressus arizonica, Pinus eldarica, Fraxinus rotundifolia, Robinia psedoacacia and Thuja orientalis whit an average age of 20 years and adjacent rangeland that converting was not created was selected as control. Sampling of soil was done in afforestation mass and control and characteristics of organic carbon, nitrogen, phosphorus, potassium, bulk density, pH, electrical conductivity, percent clay, silt and sand was measured. To compare the effect of forestry corrective operations on carbon sequestration was used independent t-test analysis and to compare the effects of different types of afforestation on soil carbon and nitrogen sequestration rates was used one-way ANOVA. Results shows that Robinia psedoacacia have a significant effect on increase of carbon and nitrogen sequestered and amount of phosphorus and potassium in soil and in total in Robinia psedoacacia mass amount of cabon sequestered and nitrogen stored in soil was calculated 80.62 and 5.42 ton/ha and in control 47.05 and 3.08 ton/ha and Robinia psedoacacia mass cause to increase of soil carbon and nitrogen amount of 71 and 75 percent and lowest amount of carbon and nitrogen was obtained in soil of Cupressus arizonica mass. Stepwise regression results showed that nitrogen, phosphorus and potassium, respectively are most important components affecting in soil of investigated mass.

In this study, the effect of land use changes on groundwater resources as well as monitoring of spatial and temporal changes of groundwater quantitative and qualitative parameters were assessed in west basin of Jazmoryan Wetland. Landsat satellite images of TM 2002 and OLI 2015 sensors by applying of Maximum Likelihood Method were used to investigate land use changes trend. Also, information related to wells in years of 2002 to 2015 was used to assess groundwater quantitative and qualitative parameters. To do this, zoning maps of spatial and temporal changes of groundwater quantitative and qualitative parameters were prepared using the best interpolation method in ArcGIS software. The results related to evaluation of the best interpolation method showed that Kriging method had the least error. According to the results of this study, the area of agricultural and urban land uses has been increased, while the area of ephemeral stream, dam, rangelands, bare and mountain land uses has been decreased in 1394 compared to 1381.These changes indicate the increased degradation as well as unstable conditions of the region that adversely affect groundwater resources. As a result of these changes, groundwater quality in southern parts of the study area has been declined. Among the factor causing this declined groundwater quality are construction of Jiroft dam on Halil-rood permanent river, lack of water right and expanded urban and agricultural lands which have caused decrease in groundwater quality over time.

Indiscriminate land utilization methods, forest and rangeland degradation, land abandonment and development of residential areas contribute to the changes in flow intensity, erosion rate and sedimentation. Therefore, having knowledge on the effect of land use changes on discharge flow and sediment yield has been found necessary. The present research aims at investigating the effects of these factors by means of the semi-distributed Soil and Water Assessment Tool (SWAT) in Galikesh watershed, Golestan province (as a tributary of the River Gorganroud), in an area covering approximately 39000 hectares. This model was used in a 27-year period for simulation, calibration, validation and optimization of the parameters affecting flow and sediment yield. Land-use maps were prepared form the Landsat imageries dated 1987, 2000 and 2013. The SUFI2 model was used for model calibration and validation. Nash-Sutcliffe (NS) index was used as the objective function during model calibration (1990-2007) for the simulation of discharge and suspended load, which resulted in 0.63 and 0.61 that could be interpreted as satisfactory compared to the standards set in previous research. To evaluate the effect of land use changes on runoff and sediment yield, all model inputs, other than land use, were assumed constant. The results demonstrated that land use changes since 1987 to 2013 have led to an increase in annual runoff height by 1.40 mm and annual sediment concentration by 2 t.ha-1.

Urbanization has led to development the impervious surfaces and subsequently changes in urban hydrology. The aim of this study is investigate the effect of land use change and urbanization on the changes of runoff peak discharge in Zanjan City Watershed, Iran. In order to, Landsat Thematic Mapper (TM) images and Aerial photos of 1956, 2000 and 2012 has been processed by using IDRISI Selva and Geographic Information System software and land use maps prepared in six land use class and the trend of land use changes and urbanization determined. To analysis the hydraulic and hydrology behavior of three periods of land use changes and urbanization on the changes of runoff peak discharge, Stormwater Management Model (SWMM) was used. After the SWMM model calibration based on observation rainfall-runoff events, the results of model calibration and verification, confirmed the accuracy of the model simulation. The results of land use change and urbanization trend of Zanjan City Watershed show that urban areas in 2012 compared to 2000 and 1956, respectively, has increase 22.59 and 923.88 percent and in 2000 compared to 1956 has been increased 543.06 percent. The results of SWMM model show that land use change and urban development has led to increase the runoff peak discharge, so that the average change in runoff peak discharge show that it increase in 2012 compared to 1956 and 2000, respectively, 96.85 and 475.52 percent and in 2000 compared to 1956, 194.288 percent increase in average of runoff peak discharge is observed.

In Iran, natural conditions for creating a wide range of landslide are possible regarding to the severe rugged, mountainous areas, high tectonic and seismic activity, and various conditions of geologic and climatic. This subject imposes the annual loss of life and huge economic losses to the country. Factors affecting landslides are also different so the extent of the difference among watersheds as well as vegetation and rainfall are different in each region of forest habitat. Researchers studies based on forest habitat showed that the effective factors on land slide are including more human factors than natural ones, i.e. land use change and establishment of infrastructures such as roads, dams, gas and oil lines and so on that could be managed technically. Human factors had majority of landslides occurred in a way that directly or indirectly impact on natural factors play an important role. In addition, reducing the country's forests because of the lack of integrated management plans in the country has been influential in increasing the landslides occurrence. So, the study on stability of slopes is necessary to build new infrastructure in the each forest habitat.

Changes of land uses have recently been increasing due to anthropogenic and climatic factors while in order to manage the land and natural resources, having monitoring data of these changes is necessary to make the decision and programming for now and future of the land. Kessillian watershed was considered to simulating of coming changes of land-use. Hence, land-use and land cover maps of the catchment was prepared by using multi-period Landsat images such as 1986, 2000, and 2011 years. The integration of cellular automaton and Markov model was then applied to survey the land-use/land cover condition in 2011 using ROC (0.9) and was also foreseen land-use/land cover for 2030. Regarding detecting and simulating of the changes, forest lands were decreased process and rangelands and inhabited areas were increased. The agricultural lands have not seriously changed because of steep slope and low fertility during the time. In most cases, the maximum changes were occurred around the forest and rangelands areas and the change trends will be decreased to give a wide berth to these lands. Markov model can precisely show the land changes in the area via time period and can anticipate the future of them. Therefore, this model can be applied in order to manage the land.