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

The most important human impact on the hydrological cycle of watershed is land use change. Improper management of land use increases the volume of runoff and the frequency of floods. The main purpose of this study is to investigate the effect of land use change on discharge outflow in Karkhane Watershed using the Parameter Allocation Approach. Then, utilizing the philosophy of a modelling framework proposed by Bahremand (2016), we show how calibration of most model parameters can be avoided by allocating or presetting these parameters utilizing knowledge gained from sensitivity analyses, field observations and a priori specifications as a part of a parameter allocation procedure. Evaluation of the WetSpa model performance using the Allocation Parameter Approach to simulate the daily hydrograph based on the Nash-Sutcliffe and Kling-Gupta showed that the values of these criteria are 60.18 percent and 76 percent respectively. Based on this efficiency criterion, the model in the parameter allocation approach has a good performance and shows consistency in the validation period. The results showed that land use change affects the runoff of the Karkhane watershed so that in the pessimistic scenario 2, the peak discharge has increased by 15.74% and in the optimistic scenario 3; the peak discharge has decreased by 11.33.

One of the important challenges and issues in land management programs is that of physical growth of cities in different directions over time. The transformation of non-urban watersheds into urban ones has led to some environmental challenges and problems. An overall management plan needs accurate spatial information at consecutive times. Remote sensing technology offers great help in identifying and detecting land use changes. The aim of this study was to detect land use changes using images collected from 1991 and 2001 Landsat 5 satellite¢s TM sensor and 2018 images provided by the Landsat 8 satellite¢s OLI sensor over a period of 27 years on Abshuran Watershed, the Kermanshah. Following the required procedures in the preprocessing stage, a change detection map was prepared with an acceptable accuracy with supervised classification in the ENVI5.3 software environment. The results indicated that during the 2001-2018 periods, about 1.17 % of the share of the rangeland and farmland decreased and that the urban and residential lands increased from 5.92 % to 17.19 % of the total area. Most of the land use change has occurred in the urban and residential areas, thus an increase in the impermeable areas causes an increase in natural disasters such as flooding in addition to some negative effects on natural resources.

Wetlands are an integral part of the semi-arid and arid ecosystems, which are inundated during major floodings and are transformed into sources of particulate matter during drought. This phase of their life cycle is very disturbing as they affect breathing in downwind areas and result in many pulmonary diseases. Thus their management is very challenging. As the Mansuriyeh Wetland (MW) is transformed into a dust source when dry, and threatens the City of Ahvaz with dust storms in the lean years, and this is mainly caused by an eradication of the vegetative corer, it was decided to survey the area when the MW was brimmed with floodwater. This was achieved benefiting from the images collected by the Landsat TM, ETM+ and DLI during the June of 1988 through the same month in 2017, and the rainfall data provided by the National Meteorological Organization. Analysis of the information was carried out in three steps: preprocessing, preprocessing and post preprocessing using the support vector machine (SVM) along with the ENVIs software. Likewise the image were classificed into the inundated areas the land covered with vegetation, water and the bare land. Truthfulness of the image was validated through Google Earth employing the total accuracy and the kappa procedures. The percentage of the area covered by each class was determined through the GIS zooning. The area contributing water to the MW was determined as its watershed, the rain-gauging network was plotted on the maps, and the mean annual precipitation of the entire watershed was calculated and drought occurrence and its intensity were determined using the standard precipitation index (SPI): the R2 for this item was 0.6. Therefore, variation of the MW as a dependent variable is related to the drought as an independent variable. Thus drought is 60% responsible for dust formation. Other variables, namely numerous small earth banks, oil well drilling installation and agricultural activities may also contribute to dust formation. Variations in the extent of the bare area and its relationship with the dust formation indicated that 80% of the MW had dried during the previous10 years. Moreover, up to 100% of the area had been entirely without a vegetative cover in some of those years. Salinity of a fine- grained soil, also made it a potential source of dust storms that invaded the Ahvaz Metropolis.

Clarification of suspended load (SL) supply variations at different temporal scales is essential to provide a logical management program. In this study, the SL transport variations were investigated at different time scales in the Marboreh River, Darreh-Takht, Lorestan Province, Iran. The four seasonal, seasonal threshold, annual and land use period approaches were analyzed using statistical methods based on the collected data from 1971 to 2016. The seasonal threshold runoff was determined using the best statistical distribution for the return period of 2 years, and the SL concentration-runoff relationships were prepared for large and small events. The land use map was prepared using remote sensing data for the years 1977 and 2016. According to the results, supply and SL transport capacity were high in the large events of spring, when the slope of the sediment rating curve is 1.469. The supply and SL capacity for large events of the autumn was higher than that of the winter. In the study period, although the land use change from rangeland to dry-farming was observed, the impact of other human activities including dam construction on the tributaries has caused a decrease in the mean SL transport, corresponding with the daily runoff in autumn, winter and spring.

The main objective of this research is investigating the effects of land use change on hydrological conditions in the Firoozkouh Watershed. Land use maps for the years 2000 and 2014 were prepared through a synthetic method using the Landsat 5 and 7 satellite imagery. Runoff simulation was carried out on a daily basis for 8 years (5 years for calibration and 3 years for validation) using the WetSpa model for land use in 2000 and 2014. Land use change showed that conversion of rangeland to farm fields and residential areas is the main change of land utilization in the Firoozkooh Watershed. Results showed that total runoff, surface runoff and peak discharge had increased following land use changes from 2000 to 2014. The total runoff in 2000 was 1480.22 m3h-1, and for the year 2014 it was 15350 m3h-1. Results showed that parts of the rangeland in the Firoozkooh Watershed, which had been converted to farmfields become agricultural and residential area during the past years had increased changed the runoff volume as well as peak discharge

Careful monitoring of spatial and temporal change of ground level complications to understand the relationships and interactions between human and natural phenomena in order to better decision-making is very important. Remote sensing data are the primary sources that are widely have been used to monitor changes in recent decades. In this study, the land cover changes using three time satellite images i.e. 1988, 2001 and 2010 in Ilam Arkavaz watershed has been studied. Therefore, each of the images were classified using maximum likelihood method. The main identified classes are residential, agricultural, garden, forest, pasture and land without vegetative cover. Area of this land use classes for each year is determined and compared. Analysis of temporal changes of images shows the percentage changes over the 22 years studied in land use classes were as Residential 56.03, agriculture 24.85, garden 65.93, forest 27.4, pasture - 15.3 and no vegetation cover 27.45. The results indicate that the forest and pasture areas of have been facing with reducing the area and the annual rate of decline forest area in this watershed is 0.97 % that is higher than the global average (0.2 %). This situation indicates a worrying decline in forest cover in the region.