جستجوی مقالات مرتبط با کلیدواژه « qom province » در نشریات گروه « آب و خاک »

Land-use change is an important factor in changing the hydrologic processes and biodiversity. It has significant environmental consequences at local, regional, and global scales. Although many studies have been conducted for revealing the land-use change worldwide, its impact on the hydrologic processes, water resources, water supply, and water consumption is poorly understood.

The present research is an effort to use remote sensing techniques for investigating land-use change in Qom province during the last three decades. Qom province, located in the west of the Dasht-e-Kavir desert with vulnerable water resources, has been subject of a rapid development process in recent decades so water resources require more attention. Here, Maximum Likelihood Classification (MLC) and Decision Tree Classification (DTC) were used to show the role of the classification method in the results.

The results showed that “drought” and “increasing number of farmers”, with an average score of 3.56 and 3.45 respectively on a scale of 1 to 5, are considered as the main causes of agricultural water conflict. From the farmers’ view, the priority for reducing water conflicts was the participation of farmers in managing water wells and negotiating with farmers around the water. On a scale of 13 to 65 with an average of 38.51, the perceived agricultural water conflict was at the medium level. By increasing farm distance from the well, area of agricultural rental land, and annual income from non-agricultural activities, the perception of agricultural water conflict increased. However, by increasing owned agricultural land area and agricultural income, the perception of agricultural water conflict decreased. The main strategy used by farmers to manage agricultural water conflict was “control”, in which coercion and force are used to manage conflict. The “problem-solving” and “avoidance” strategies were the second and third priorities respectively.

Nowadays the dust phenomenon is one of the biggest environmental problems in the world, causing major damage to sectors such as industry, transportation, agriculture, tourism and human health each year. The dust storm, which commonly occurs in arid and semi-arid regions such as the central and southern parts of Iran, carries a large amount of dust and reduces daily human activities and horizontal visibility. According to the World Meteorological Organization (WMO), when the wind speed exceeds 15 meters per second and a large amount of dust enters the atmosphere so that the horizontal visibility reaches less than 1000 meters, dust storms are reported. The creation of dust is caused by natural and man-made factors, the human component of which is mainly a response to changes in soil cover and land use. One of the objectives of the present study is to monitor the location and source of dust (origin and destination of dust) and the movement of dust storms and streams/trajectories containing dust.

In this study, meteorological data including temperature, relative humidity, rainfall, evaporation, wind speed and number of dusty days from 3 meteorological stations of Qom province were obtained from Meteorological Organization and analyzed. Also in this study, to determine the potential dust sources by the maximum likelihood and minimum distances classification methods was done to determine the land use and soil type of different areas with Landsat images. This process was completed using time series images of Qom province in 30 years, from 1989 to 2019 with 5-year steps and monitoring the changes of this period with in 11 different classes. Next, according to the recorded dust data (horizontal visibility) at Shokouhieh/Qom Meteorological Station showing the occurrence of dust storms as defined by the World Meteorological Organization, backward tracking of air trajectories using the HYSPLIT meteorological model. The backward trajectory, if it is close to the surface of the earth and the area potentially capable of spreading dust from the surface into the air, can be considered as the source of the dust phenomenon.

The results identified 30 areas with different soils and cover as the source of dust. There were 20 spots of bare land, 5 spots of salt land and 5 spots of sandy land. The main sources of dust storms studied in this province are located in the eastern half of the province adjacent to the Namak Lake and the Dasht-e Lut. In the final part of the present study, meteorological data that directly report the occurrence of dust storms were first analyzed. Then, based on the recorded data and some restrictive conditions, the target dates that the dust storm defined by the World Meteorological Organization at that time were selected. Codes w=06 and w=07 are related to the dust phenomenon, and both codes are used in this study. One of the innovations of this research is the combined view of soil cover and land use in the study area and also the investigation of dust events.

The results of HYSPLIT model show that the main sources of dust events studied in this study are from neighboring eastern regions such as Semnan. These storms are ultimately considered as a domestic dust event. About 15 percent of the total dust storm events in the studied dates are likely to have been foreign dust. These events are mainly of foreign source and have been imported from western and southwestern Iran countries such as Iraq, Saudi Arabia and perhaps Syria and are modeled as foreign dust and generally considered as sever dust storms.