عنوان مقاله [English]
Human beings have always attempted to meet their requirements by using agriculture lands for many years. This is changed in such a way that today with present population with diversity of human needs and overuse of land, they created many adverse effects. Wide areas of natural resources disregarding ecological principles to meet their needs have been turned into the degraded lands, while many of these lands have not been cultivated with a high erosion potential. Having knowledge of land use and its changes and reviewing possible causes are important in planning and policy-making in the country. The ratio of land use changes can help to anticipate upcoming changes and perform appropriate actions. Remote sensing techniques can be helpful to detect changes in land-use patterns as great resources for management and planning. The aim of this study was to investigate changes in land use and land cover based on the data derived from satellite images, since these changes along with environmental effects have different impacts on the economy and living conditions of beneficiaries. In addition, the assessment of the following direct economic impacts on land use change considered living and livelihoods of all residents of the area.
Materials and methods
Behbehan city is located in the southeastern areas of Khuzestan and limited to the cities of Kohgiluyeh and Boyer Ahmad provinces. The job activity of the majority of the villagers is agriculture and animal husbandry. There are three types of vegetation, bushes and grass cover in Behbehan. In this study, we used Landsat satellite images, Landsat TM data in 1991 and the Landsat OLI satellite images of in 2016, general aerial photographs of 1: 20000, numerical topographic map of 1: 25000, and GPS data (Etrex Model). In the first step, the satellite images were processed and geometric and atmospheric corrections are made to prepare the raw image data. Then, we have used maximum likelihood method for supervised classification. After selecting training samples of the images from 1991 to 2016, we used maximum likelihood classification in ENVI to classify the images. Using the clasification method, we divided the images into 6 classes of woods, grassland, agricultural areas, abandoned land, residential areas and water groups. The classification accuracy for image was assessed by using the kappa index. The communities affected by changes in land use were identified in order to evaluate the effects of changes on economic dimension of beneficiaries. At the end, we have analyzed the changes in economic situation of people due to landuse changes.
Results and discussion
After classifying maximum likelihood classification in ENVI, land use maps were obtained from 1991 and 2016. The maps are related to the two time periods (1991-2016) evaluated by overlaying the two maps in GIS environment to obtain change map. The results indicate that the forest area in 1991 was 9348.93 hectares and with 4.57 percent decrease reached to 8812.53 hectares in 2016. The area of pasture is also decreased by 36.63 percent and it has decreased from 86596.92 hectares in 1991 to 82297.71 hectares in 2016. The agriculture land-use has increased 11.72% from191.61 hectares in 1991 to 1567.26 hectares in 2016. The area of abandoned lands has also increased from 15137.19 hectares in 1991 to 18413.91 hectares until now. Residential areas have also increased from 1044.27 hectares in 1991 to 2337.39 hectares in 2016. Water level is faced with a reduction in 2016 and it was more than 1399.05 hectares in 1991 and reached to 444.69 hectares in 2016, a decrease of 8.13 percent. The reduction of 536.4 acre in the use of forest and palm groves caused £ 25064958204decrease. A decrease in 4299.21 acre of pasture caused £2923462800 of devaluation. Increase in the agricultural use of lands caused increased income, equivalent to £ 825390000000. Increase in abandoned lands caused decrease in income and consequently devaluation of £ 318168655183.
Given that in this study period, residential areas has increased due to increased urban population and immigration, the need of people for housing has, consequently, increased. The pasture area has been reduced in this period since they are changed these lands over time in recent years. Because of increase in the use of agricultural lands and unprincipled irrigation using traditional methods, water resource and droughts are, consequently, declined in recent years. With increasing population and development of residential areas, it is needed to fix the problem and this reduces natural resources (pasture, water and forest). Although land use change and decrease in the level of natural resources during this period had not so negative complications, but continuation of this process and non-normative change of land use can have more negative consequences in the long run. Therefore, we have to determine uses which are compatible with the environmental potential and capacity of lands.