فصلنامه جغرافیای طبیعی
پیاپی 52 (تابستان 1400)

In agricultural climate, it is important to know the climatic characteristics of each region in order to adapt it to the cultivation of each plant and increase production. In the present study, the time of occurrence and temperature thresholds of pistachio tree phenological stages at BBCH scale were determined in the field. Then, using non-parametric Mann-Kendall method and Sense slope test, the trend of changes in the elements of average humidity on the day of completion of each stage, average humidity, average maximum and minimum temperature, average temperature on the day of completion of each stage, average soil temperature, average wind speed, rainfall And sundial at Gonabad station during the statistical period of 1398-1398 on pistachio growth. Findings of this study showed that depending on the degree of day at different possible levels, the length of pistachio biological activity in this region varies from 163 to 198 days and the minimum and maximum total hours of sunshine are required to be 177.57 and 1261. The climatic element limiting the biological activity of pistachio plant as well as other climatic parameters were identified. In the next step, Mann Kendall test was used to examine the trend of climatic elements in different stages of pistachio crop phenology. The results of this study showed that among the climatic parameters of pistachio cultivation, average relative humidity, maximum and minimum temperature, average temperature, wind speed and sundial have a significant increasing trend at the level of 5%.

The aim of this study is climatic-agricultural empowerment of rain-fed wheat and sugarcane cultivation using three methods FAO, Papadakis and UNESCO in Khuzestan province. Areas prone to dryland wheat cultivation have been used. For this purpose, 23-year statistics (1994-2016) daily climatic data related to temperature, precipitation, sundial, relative humidity and wind direction and speed of 10 synoptic stations in the province were used. The results of this study showed that most parts of the northern and northeastern regions of the province are suitable for dryland wheat cultivation and the southern and southwestern parts were unsuitable in this regard. In the meantime, the efficiency of the two methods of FAO and Papadakis was better than that of UNESCO. One of the remarkable results of this study is the identification of potential areas for sugarcane cultivation in Khuzestan province by the results of two methods, FAO and Papadakis. According to the results of these two methods, the central, southern and southwestern parts of the province are suitable for sugarcane cultivation, while according to the realities of the region, this plant is cultivated only in Ahvaz city. In the case of sugarcane, neither FAO nor Papadakis has been superior in efficiency.

Trihalo-methanes have been identified by the Cancer Research Institute as a carcinogen for humans. Considering that in Haft Rousta project, the source of drinking water supply is groundwater and water of Darood Zan dam and disinfection used is chlorine, this study was conducted to determine the concentration of trihalomethanes in drinking water of Haft Rousta project. The present study was conducted in the spring and summer of 2017. For this purpose, three villages (Abbasabad, Majd Abad, Kemar Zard) from Marvdasht city of Fars with a total of 9 stations were selected and the amounts of chlorine, pH, temperature, total organic carbon and trihalo methane were measured with three replications in water samples. The average concentration of trihalomethane compounds in this study was estimated to be 39 mg / l for Abbasabad village, 38.6 mg / l for Kemar Zard village and 39.7 mg / l for Majd Abad village. The highest recorded concentration was calculated in Majd Abad village with a concentration of 73 mg / l. The mean concentrations of chloroform, bromoform, bromodium chloromethane and dichloromethane and totality of halo methanes in network water in spring 1996 were 22.25 7 7.98, 11.42 90 3.90, 7.43 7 2.72, 51, respectively. 5.95 2 2.2, 47.06 15 15.70 mg / l in summer 96 are equal to 14.69 4 4.11, 7.55 99 1.99, 4.93 51 1.51, 1.49 3.95 ،, 31.13 97 7.97 mg / l were calculated. Due to the concentration of trihalomethane in the drinking water of the study area, the possibility of trihalomethane compounds due to the consumption of the studied waters is very low and the presence of this pollutant in this danger does not affect consumers in any age group.

Drought is a natural and recurring feature of the climate that occurs in all climatic regions, but its structure and important effects vary from region to region.The main purpose of this study is to investigate the country's meteorological droughts over a long period of time using network data with appropriate spatial and temporal resolution. Data analysis was performed using SPEI multivariate index. The results of drought calculation showed that in terms of time during the period (1966-2015) the rainfall of the cold period of the year decreases in general, the decrease in rainfall in different parts of the country mainly starts from the late 90s In the last years of the study period, except in autumn, we see more repetition of dry periods and unlike the late 80s, droughts have occurred more. Moderate drought intensities are significant and experience of severe droughts, which are among the most critical areas of the country.

Land Surface Temperature (LST) is one of the most important variables that provides important information about the physical and chemical properties of the litosphere, atmosphere and hydrosphere. Since this variable represents the first thermal reaction to environmental changes, its analysis can provide valuable information to environmental scientists. In recent years, MODIS sensor data have been widely used to estimate LST. In the present study, MODIS sensor data (MOD11C3 & MYD11C3) were used to analyze the daytime LST on the Jazmourian basin (2003-2019). Extracted data were used after quality control and necessary processing to estimate daytime LST. Based on the results; LST values in the Jazmourian basin range from 20-55 °C and clearly follow the altitudes and latitudes. Seasonal analysis of the LST spatial distribution shows the winter and summer seasons with a range of 5-40 °C and 35-65 °C as the coldest and warmest seasons, respectively. Also in the monthly spatial distribution of LST, January and February had the lowest and June and July had the highest LST. The time series trend of LST anomaly indicates an increase of about 0.5 °C in the study period. Also, the spatial distribution of LST indicates the maximum of positive anomalies in the southwestern and central parts and the minimum of positive anomalies in the east of the basin.

Karst aquifers in semi-arid regions play a vital role in people's lives. Therefore, recognizing the pollution potential of aquifers and their vulnerability in different sectors is very important. The western region of Iran, due to the expansion of the Zagros carbonate mountain range, has numerous karstic aquifers that are exposed to pollution in terms of environmental conditions and extensive human activities. The purpose of this study is to estimate the vulnerability map of Aleshtar plain karst aquifer located in Lorestan province against COP pollution. This model evaluates the vulnerability of karst water sources to pollution using three factors, cover layer (O), flow concentration (C) and precipitation regime (P). The results show that 19.14, 28.76, 35.01 and 17.09% of the area are located in very low, low, medium and high vulnerability zones, respectively, which indicates the almost low vulnerability of this karst aquifer compared to It is pollution. Findings indicate that the importance of the overlay factor, precipitation regime factor and flow concentration factor in the pollution of Aleshtar aquifer, respectively. Due to the small area of ​​fully developed karsts and the high slope of areas with developed karst, the role of flow concentration factor in pollution of Aleshtar aquifer is less and due to the drought trend of recent decades and the change of precipitation from snow to rain showers that water retention and therefore less penetration In the karst basin of Alshtar, the importance of the rainfall regime in the vulnerability of the Alshtar aquifer has decreased. Finally, due to the high permeability of the alluvial plain of Aleshtar, the cover layer has provided the ground for aquifer pollution. In general, in the study area, C, P and O, respectively, have the most role in the vulnerability of the area.

Landslides are one of the most destructive types of erosion on slopes, which causes a lot of financial and human losses. The purpose of this study is to evaluate the efficiency of landslide potential zoning models in Qazvin province and to provide management strategies to reduce landslide risk. The proposed relationships of this model were used for the Haeri-Samiei experimental model. For the statistical model, after preparing the layers of effective factors (land use, slope, slope direction, height, etc.) and cutting them with a landslide distribution map, the area and percentage of landslide in each floor were determined from the effective factors map. Then, using the frequency ratio, the importance of each class of effective factors was calculated and a map was prepared based on the importance of effective factors in the GIS environment. Finally, to prepare a landslide hazard map, the maps were grouped together based on the rate of factors and classified according to the method of intervals equal to seven floors. Density ratio and total utility indices were used to evaluate the efficiency of the models and select the superior model. The results showed that the bivariate statistical model with Qs equal to 0.938 has a higher accuracy than the Haeri-Samiei model with Qs equal to 0.622. To reduce damage and manage landslide risk, three non-action management policies for low risk classes, prevention for medium risk classes and treatment for high risk classes were considered and some necessary measures were provided for each management policy.

Climate change is one of the greatest dangers facing human beings now and in future generations. The phenomenon of climate change has caused many changes in spatial patterns of rainfall and has led to an increase in marginal phenomena such as drought. It is also predicted that climate change will affect the frequency, severity and duration of drought. Drought occurs in all climates, even in humid and semi-humid climates, so wetlands, which are one of the most important habitats on Earth, are no exception. In this study, drought events in Anzali wetland and its relationship with changes in wetland area during the statistical period 1975-2016 have been investigated. Two SPI and RDI indices have been used to study drought. Landsat satellite imagery was used to determine the blue zone. The study of drought indices in Anzali wetland shows that the values ​​obtained by RDI index estimate drought with less intensity than the values ​​obtained by SPI index. The results also showed that the water area of ​​Anzali wetland has a decreasing trend during the years under study, which is completely consistent with the increasing trend of drought in terms of frequency and severity.