A B S T R A C T Temperature is one of the climate elements that has fluctuated a lot over time. When these fluctuations increase AND decrease more than normal AND are placed in the upper AND lower regions of the statistical distribution, if continued, it can lead to the creation of heating AND cooling waves. The purpose of this study is to analyze the TEMPORAL AND SPATIAL changes in heating AND cooling waves in Iran during a period of 50 years. For this purpose, the temperature of 663 synoptic stations from 1962 to 2004 was obtained from the Esfazari database. Then, in order to complete this database, the daily temperature from 2004 to 2011 was obtained from the Meteorological Organization of the country AND added to the aforementioned database. In order to perform calculations AND draw maps, Matlab, grads AND Surfer software have been used. The results of this study showed that the index of cooling waves AND heating waves, while having a direct effect on each other, had an increasing trend in most of the area of Iran. The statistical distribution of the index of cooling waves is more heterogeneous than that of the index of heating waves. So that the SPATIAL variation coefficient for cold waves is 84.22%. Also, the index of cooling waves has more SPATIAL variability. The highest common diffraction of the index of heating AND cooling waves has been seen in the northwest, east AND along the Zagros mountains. Analysis of the indexes trends show that heat waves have intensified in 65.8% of Iran AND the intensity of cold waves has decreased in 48.5% of Iran Extended Abstract Introduction Temperature is one of the major climatic variables, which it has a direct impact on different aspects of human life. It plays an essential role in the growth of crops AND is considered a key driver of the biological system(Reicosky et al, 1988). It is associated with several types of extremes, for example, heat AND cold waves which caused human societies maximum damage. Past occurrences of heat waves hitherto had significant impacts on several aspects of society. Have increased Mortality AND morbidity. Ecosystems can be affected, as well as increased pressure on infrastructures that support society, such as water, transportation, AND energy(Dewce, 2016). The long-term change of extreme temperatures has a key role in climatic change. The form of statistical distribution AND the variability of mean values AND also extreme event indicate a change in the region. It can be a small relative change in the mean as a result of a large change in the probability of extreme occurrence. Also, the variation in temperature data variance is significantly more important than the mean, for assessing the extreme occurrence of climate(Toreti AND Desiato, 2008). The average surface temperature has increased the world between 0.56 AND 0.92 ° C over the past 100 years(IPCC, 2007). Meanwhile, it was in the Middle East, the average daily temperature increased by 0.4-0.5 ° C in decades(Kostopoulou et al, 2014; Tanarhte et al, 2012). Considering that not many studies have been done in the field of spatio-TEMPORAL VARIATIONS of the heating AND cooling waves thresholds in Iran, in this study, the spatio-TEMPORAL VARIATIONS of the heating AND cooling waves thresholds in Iran during 50 years were examined AND analyzed.   Methodology The daily temperature from the beginning of the year 21/03/1967 to 19/05/2005 was obtained from the Esfazari database prepared by Dr. Masoudian at the University of Isfahan. In order to increase the time resolution of the mentioned database, the daily temperature of observations from 05/21/2005 to 05/12/2012 has been added to the mentioned database using the same method, AND the exact SPATIAL resolution (15 x 15 km) is used as a database. Threshold indices of heating waves are the average numbers between the 95th AND 99th percentiles, that is, the extreme hot threshold to the limit of excessively extreme hot. For extreme cool, from the 5th percentile down to zero is used. Of course, a condition was added to these thresholds, which is that these thresholds must be repeated two days in a row. These thresholds were extracted for each day in the 50 years of the study period AND used as the original database. In order to analyze the relationship between cooling AND heating waves, Pearson's correlation coefficient was used AND regression was used to analyze the trend.   Results AND discussion The average of cold waves was 5.26 ° C AND for the heat waves is 30.20° C. Generally, if the temperature is upper or lower than this threshold, it is considered as hot or cold temperatures. A comparison of the median, mode, AND average of cold waves with heat waves shows that the distribution is more heterogeneous for cold waves AND its CV is 84.22%. In southern Iran, the average threshold heat waves are higher. This situation can be caused by the effects of subtropical high-pressure radiation, low latitude, AND proximity to the sea. Though the threshold is higher in these areas, fewer fluctuations AND changes are seen in the area. Heights moderate the temperature so they pose a minimum threshold for heat waves i.e. an iso-threshold of 25 ° C is consistent along the Zagros mountain chains, but in the west AND east of Zagros Mountains, the threshold of heat waves is increased. Heat waves have increased in most areas of the country. So nearly 85 percent of the Iran has been an increasing trend, of which 65.8 percent is statistically significant at the 95% confidence level. Still, more areas of the country (60 percent) have a trend between 0.00828 AND 0.00161. As can be seen, only 15% of the lAND area (including the southwest AND northwest of the Country) had decreased heat waves. Cold waves, in most parts of the country, have a Positive Trend. However, about 25 percent of the study area's cold waves have a negative trend. they are located in areas higher than Latitude 30°. The largest decline of the wave's trend along the country is highlANDs. Nowadays, most of the country, has a trend between 0.01494 AND 0.00828 ° C, respectively. Conclusion Common changes AND effects of heat AND cold waves had a direct relationship in many parts of the country. It is remarkable common variance in the East reached 55 percent, according to statistical significance. In some areas of the northwest AND southwest, which have been impressive heights, the common variance is 40 percent. This common variance in mountains area has been high values. Investigation of heat waves trend shows that 65.8% of Iran significant positive trend AND 7.1% significant negative trend. Also, the cold waves trend has indicated a 48.5% significant positive trend AND a 10.8% significant negative trend. Climate change AND global warming have changed the frequency AND severity of temperature extremes. The present study, by examining the number of warm waves, concluded that the warm waves have increased in magnitude in 65.8% of the Iran zone. Also, the study of the cold waves trend showed that 48.5 percent of Iran had a positive trend, which means that the amount of temperature in the cold waves increased In other words, the severity of the cold has been reduced AND only 10.8 percent of Iran had a negative cold wave trend AND it shows the intensity of these waves is reduced.   Funding There is no funding support.   Authors’ Contribution The authors contributed equally to the conceptualization AND writing of the article. All of the authors approthe contenttent of the manuscript AND agreed on all aspects of the work declaration of competing interest none.   Conflict of Interest The authors declared no conflict of interest.   Acknowledgments  We are grateful to all the scientific consultants of this paper.

AbstractThis study aimed to evaluate the TEMPORAL AND SPATIAL VARIATIONS in surface soil moisture in Iraq, taking into account the influence of both natural fluctuations AND human activities on environmental changes. Volumetric soil moisture data with a resolution of 0.25 degrees AND daily intervals covering a thirty-year period (1991-2020) were obtained from the Copernicus climate database. Trend analysis was conducted to examine TEMPORAL AND SPATIAL trends in soil moisture levels. The results indicated a decrease in volumetric soil moisture during warm months AND an increase during cold months, with the latter period exhibiting soil moisture values more than twice as high as the former. Furthermore, a declining trend in volumetric soil moisture during the cold months in Iraq was observed based on the evaluation of monthly time series. The average annual volumetric soil moisture in the country was estimated to be 0.164 m3/m3. The lowest soil moisture value was found in southern Iraq near the border with Kuwait (0.093 m3/m3), while the highest value was recorded in the northeastern mountainous region of Iraq (0.240 m3/m3). Notably, there was a gradual decrease in soil moisture from north to south in Iraq. The analysis of maps revealed that the most substantial decreasing trends occurred in January, February, AND March, progressively diminishing as the warm season approached. These decreasing trends were predominantly observed along the rivers of Tigris AND Euphrates, as well as around the Razazah Lake AND the Tharthar Lake extending from northwest to southeast. The provinces of Diyala, Maysan, AND Wasit, particularly Wasit, consistently exhibited decreasing trends in soil moisture in most months, indicating their vulnerability to soil moisture reduction. Keywords: Volumetric Soil Moisture, Trend Tests, Copernicus Climate Database, Iraq  Introduction:Soil surface moisture is a crucial variable in hydrological processes that influence water AND energy exchanges at the Earth's surface AND in the atmosphere. Accurate estimation of TEMPORAL AND SPATIAL VARIATIONS in soil moisture is vital for various environmental studies. In recent years, remote sensing techniques combined with satellite observations have enabled the measurement of soil surface moisture, providing valuable global-scale information for monitoring AND drought prediction (Wang & Qu, 2009). Despite its relatively small quantity, soil moisture plays a significant role in the global water cycle (McColl et al., 2017). The lAND of Iraq with its ancient civilization owes its existence to the life-giving rivers of Tigris AND Euphrates. Despite being located in an arid belt, these rivers have mitigated the adverse effects of the high-pressure desert climate, transforming the otherwise dry AND arid lAND into a lush AND vibrant region. However, human interventions in the environment, such as dam construction on the tributaries of the rivers, as well as the impacts of global warming leading to increased temperature AND irregular rainfall patterns, have resulted in changes in soil moisture in Iraq. Consequently, extensive areas of the country, particularly along the rivers of Tigris AND Euphrates, have experienced a significant decrease in soil moisture. Materials & Methods:In this study, soil moisture data obtained from the Copernicus database were utilized. The dataset covered the period from 1991 to 2020 AND provided daily TEMPORAL resolution AND a SPATIAL resolution of 0.25 x 0.25 degrees of latitude AND longitude. The soil moisture data used in this research represented the volumetric soil moisture content measured in cubic meters of water per cubic meter of soil (m3/m3). To analyze the trend in the time series of soil moisture data, the Kendall test, a non-parametric method, was employed. The Mann-Kendall method initially introduced by Mann (1945) AND further developed by Kendall (1970) was used as well. The null hypothesis of the Mann-Kendall test assumes rANDomness AND the absence of a trend in the data series, while the alternative hypothesis (rejecting the null hypothesis) indicates the presence of a trend. A positive Z statistic indicates an upward trend in the data series, while a negative value indicates a downward trend. One notable advantage of this test is that it does not require the data to follow a normal distribution, making it robust in analyzing non-normal data. Research Findings:The average annual volumetric soil moisture in Iraq was 0.164 m3/m-3 with significant SPATIAL variation ranging from 0.068 to 0.286 m3/m-3, indicating an uneven distribution across the country. The SPATIAL variability coefficient was relatively high at approximately 23.6%. The southern regions of Iraq bordering Kuwait exhibited the lowest levels of volumetric soil moisture, while the highest levels were observed in Baghdad Province, gradually decreasing towards the surrounding areas. Overall, there was a northeast-southwest trend in volumetric soil moisture in Iraq with values decreasing from the northeast to the southwest. This pattern was influenced by the topography AND geographical location of the rivers of Tigris AND Euphrates. In the northeastern mountainous region of Iraq, the volumetric soil moisture was approximately 0.18 m3/m-3. Conversely, in the foothill region encompassing Sulaymaniyah, Kirkuk, Erbil, Dohuk, AND the northern half of Nineveh Province, the moisture content exceeded 0.2 m3/m-3 AND occasionally reached beyond 0.26 m3/m-3. Analyzing the monthly VARIATIONS in soil moisture revealed distinct patterns. For example, in January, about 54% of Iraq experienced a decreasing trend in soil moisture. This trend extended in a northwest-southeast direction along the rivers of Tigris AND Euphrates, covering provinces, such as Diyala, Wasit, Maysan, Qadsiyeh, Babol, Dhi Qar, Basra, AND Mushani. In February, a decreasing trend was observed in approximately 42% of the area of Iraq. The February trend map showed similarities to the pattern observed in January, albeit with lower intensity. The SPATIAL extent of decreasing trends widened in a northwest-southeast direction along the rivers of Tigris AND Euphrates. In March, declining trends covered around 24% of the area of Iraq, particularly along the northwest-southeast direction along the Tigris River in the provinces of Diyala, Wasit, AND Misan, exhibiting increased density AND intensity. In April, around 12% of the area of Iraq experienced a decreasing trend. These declining trends followed a specific geographic pattern, mostly occurring along the Tigris River AND including provinces, such as Diyala, Wasit, Misan, AND parts of Basra. In May, a similar geographic pattern was observed, with approximately 12% of the area of Iraq exhibiting declining trends. These trends were primarily noticed along the Tigris River in Wasit, Maysan, Dhi Qar, AND parts of Basra, as well as around the Al-Razzah Lake AND the Al-Tharsar Lake, along with a portion of Kirkuk Province. The extent of decreasing trends decreased in June, while the extent of increasing trends expANDed. In July, the extent of increasing trends surpassed that of decreasing trends. Decreasing trends covered 7.4% of the area of Iraq primarily observed around the Al-Razzah Lake AND the Al-Tharsar Lake, as well as in parts of the provinces of Wasit, Maysan, AND Babol. In August, decreasing trends encompassed 6% of the area of Iraq mainly witnessed around the Al-Tharsar Lake, the Al-Razzah Lake, southern Dhi Qar Province, AND northern Mothni Province. The trend pattern in September mirrored that of August with declining trends covering 8% of the area of Iraq predominantly observed around the Al-Razzah Lake AND the Al-Tharsar Lake AND along the Euphrates River in Qadsiyeh Province, north of Mothni Province, AND the center of Dhi-Qar. In October, decreasing trends affected 12% of the area of Iraq primarily noticed around the Al-Razzah Lake AND the Al-Tharsar Lake, as well as along the Tigris River in the provinces of Diyala AND Wasit AND parts of the provinces of Qadisiyah AND Dhi Qar. The trend map for November highlighted the smallest range of decreasing AND increasing trends compared to other months. In this month, 97% of the area of Iraq exhibited no discernible trend. In December, a trend pattern resembling that of April was observed with 11.5% of the area of Iraq experiencing a decrease. This decrease was mainly noticed along the rivers of Tigris AND Euphrates, surrounding Al-Razzazeh Lake, below Al-Hadithah Lake, AND in the provinces of Diyala, Wasit, AND Misan. Discussion of Results & Conclusion:For this research, we utilized soil moisture data from the Copernicus Climate Base. The data had a SPATIAL resolution of 0.25 degrees AND covered the period from 1991 to 2020 collected on a daily basis. Within the geographical extent of Iraq, we identified a total of 688 cells for analysis. To assess TEMPORAL AND SPATIAL trends, we employed linear regression trend tests AND Mann-Kendall tests. In the TEMPORAL analysis, we initially explored the annual changes in soil moisture. Our findings revealed that the average volumetric soil moisture in Iraq from 1991 to 2020 was 0.1646 m3/m-3. The highest recorded soil moisture during this period was 0.1782 in 1993, while the lowest was 0.1514 in 2017. Examining the annual time series of soil moisture indicated an overall decline. Furthermore, our monthly analyses highlighted significant decreasing trends in January, February, AND March with a subsequent reduction in the extent of areas exhibiting declining trends as the warmer months approached. Conversely, the increasing trends in soil moisture were more modest during the colder months but exceeded 20% during the warmer months of the year. Geographically, the decreasing trends extended from the northwest to the southeast, primarily along the rivers of Tigris AND Euphrates. It is worth noting that the decrease in river flow attributed to the construction of dams in Turkey, particularly Ilisu Dam at the source of the Tigris River, might have contributed to this phenomenon. In conclusion, our research indicated an overall decline in soil moisture in Iraq over the studied period. The decreasing trends were most pronounced during the colder months, while increasing trends were more prominent in the warmer months. The geographical distribution of these trends suggested a strong influence from the rivers of Tigris AND Euphrates potentially impacted by upstream dam construction. These findings provide valuable insights into the patterns of soil moisture in Iraq AND can contribute to better understANDing AND managing water resources in the region.

This research aims to study TEMPORAL AND SPATIAL VARIATIONS of groundwater quality of Marvast Plain to manage these recourses. For this purpose, total anion AND cation, a percentage of sodium, Ca, Cl, EC, HCO3, K, Mg, Na, pH, SRA, So4, TH parameters were prepared AND a statistical period of 14 years (1377_1390) was selected using the evaluation of incomplete data. Semivariograms AND cross semivariograms were potted to perform geostatistcal methods AND the best model was selected with regard to more R2, less RSS AND a strong SPATIAL structure, AND an exponential model was fitted for most parameters. Then, interpolation methods, such as Radial Basis Function (RBF), Inverse Distance Weighting with powers of 1 AND 2 (IDW), Kriging AND coKriging were used. The most accurate method was selected for parameters using cross validation method AND error estimation indexes such as Mean Absolute Error (MAE), Mean Bias Error (MBE) AND Root Mean Square Error (RMSE). The results showed that coKriging is the best method for estimating most parameters (total anion AND cation, EC, Cl, Ca, K, Mg, Na, TH). Kriging is defined as the most suitable method for estimating SRA, So4 AND pH, AND RBF AND IDW with power 1 are the most fitted methods for a percentage of Sodium AND HCO3, respectively. The results showed that the density of most parameters increases from west to east AND south to north of the study area. Also, decreasing underground water quality is observed over the time.

TEMPORAL AND SPATIAL VARIATIONS of rainfall are the main characteristics of Iran climate. According to present statistics, Iran has had a dry period from 1966 to 1974 AND a wet period from 1974 to 1983. In this paper, the mentioned TEMPORAL AND SPATIAL VARIATIONS from 1966 to 1998 is calculated AND presented. The result of this study indicates the years that the mean of annual rainfall is equal to or more than the total mean are 14 years AND the years that the mean of annual rainfall is under the total mean are 19 years. In other words, skewness coefficient of frequency curre of annual rainfall is towards rainfall lower than the mean. The results of zoning of TEMPORAL AND SPATIAL VARIATIONS of rainfall, shows 7 SPATIAL patterns AND 7 TEMPORAL patterns of rainfall throughout Iran.

Accelerated soil erosion is an undesirable process that adversely affects water AND soil resources. Rainfall erosivity is an important factor in water erosion models. Accordingly, the present study was conducted to estimate the rainfall erosivity throughout Iran based on the latest available detailed rainfall data while considering its TEMPORAL AND SPATIAL VARIATIONS. To accomplish this, the data from 18 synoptic stations of the Iranian Meteorological Organization, known to have reliable data AND hyetographs with a 23 year common period, were accordingly analyzed. The kinetic energy of rain for each storm event was calculated based on Wischmeier AND Smith’s original model, i.e. the USLE, AND many of its modifications. Later, the rainfall erosivity factor was calculated on a monthly, seasonal, AND annual basis using the calculated kinetic energy. The results revealed that the greatest risk of erosivity occurred in March, December, AND November, as indicated by R factors of 0.228, 0.201, AND 0.147 MJ mm ha-1 h-1, respectively, while June AND August had the lowest erosivity factors, as indicated by R factors of 0.017 AND 0.027 MJ mm ha-1 h-1, respectively. Furthermore, analysis of the SPATIAL VARIATIONS in R verified that the Anzali AND Babolsar Stations, located in northern Iran, had the maximum erosivity values, with R factors of 11.518 AND 4.260 MJ mm ha-1 h-1, respectively. Conversely, the Bam AND Semnan Stations, located in the central AND eastern Iran, had the minimum erosivity values, as indicated by R values of 0.201 AND 0.212 MJ mm ha-1 h-1, respectively. The long term mean annual rainfall erosivity factor of Iran was ultimately found to be 1.226 MJ mm ha-1 h-1.

The study of SPATIAL AND TEMPORAL Changes in climate parameters, is one the most important issues in the world's climate research. Study of changes in cloud cover as one of the most important climate parameters is important, because clouds are in top of hydrologic cycle AND changes in them make changes in SPATIAL AND TEMPORAL VARIATIONS in other climate parameters. In this study, the SPATIAL VARIATIONS in cloud cover in country by using monthly data of 90 synoptic stations (in 03, 09, 15 Greenwich), AND cluster analysis on 18*18 kilometers cell size were done. Also the TEMPORAL VARIATIONS AND change-point in cloud cover time series was evaluated by using Mann- Kendall AND Petitt' tests. The results showed that the clustering method can classify the amount of cloud cover in the country. This method showed five separate area for the annual amount of cloud cover including South Coast region of the Caspian Sea, Azerbaijan AND Alborz regions, western Zagros AND South slopes of Alborz, south-western AND northern Central Desert region AND south AND central were presented. These areas have a good consistence with old finding about the synoptic patterns of air masses AND cyclones traces in Iran. The results of TEMPORAL analysis also showed that the trend in the amount of cloud cover in most stations of areas 3, 4 AND 5 (northern half of the country) is statistically significant. These significant trends are negative for all station, in other words the amount cloud is reduced. The results also showed that the sudden change in the series of cloud cover values in most of these stations occurred in 1990s.

Rainfall erosivity index is the most important factor which impacts soil erosion. The objective of this research was mapping SPATIAL AND TEMPORAL VARIATIONS of rainfall erosivity in the southwest of Iran. Properties of 10,000 rain storms belonging to 27 climatological stations were analyzed AND their synthetic energy (E) AND maximum 30 minute rainfall intensity (I30) were calculated. The mean annual AND monthly rainfall erosivities were calculated for all stations' data. Mapping SPATIAL VARIATIONS was carried out using Spline algorithm. The results showed that the monthly erosivity index values decrease from the north to the south AND from the west to the east of the region. Maximum AND minimum values of annual erosivity were equal to 26.39 AND 6.11 MJ.mm.ha-1.h-1.yr-1 belonging to Ivan (Ilam province) AND Brojen stations (Chaharmal Va Bakhtiari province), respectively. TEMPORAL studies of rainfall erosivity index indicated that maximum rainfall erosivity was equal to 183.7 MJ.mm.ha-1.h-1.yr-1 AND occured in winter. Existence of significant correlation coefficients between the means of monthly AND annual rainfall values AND their corresponding rainfall erosivities were 0.94 AND 0.93, respectively AND such significant correlation coefficients facilitate indirect estimations of monthly AND annual rainfall erosivities through rainfall values AND simple or multiple regression models. The results revealed higher reliability of multiple regression models consist of both means of annual rainfall AND rain storm intensities than simple regression models for estimation of annual rainfall erosivity.

Maximum temperatures affect a wide range of activities, especially in the afternoon hours AND warm period of the year. This paper analyzes the TEMPORAL AND SPATIAL VARIATIONS of mean maximum temperatures AND the highest temperatures in Iran by using the statistical methods within a 45-year period (1964 to 2008). Temperature zonings were performed by using the Raster GIS capabilities, AND evaluated by various statistical tests. Also the relationships between the maximum temperatures AND geographical factors, as well as the temperature trends were investigated via regression equations. The results revealed six different zones of maximum temperatures in Iran. Analysis of the maps AND comparison of the stANDardized b coefficients of multivariate regression models, confirmed the latitude AND then the altitude significant roles in controlling the maximum temperatures, especially during the cold period of the year, along with the lowest temperature variabilities in the southern coasts. Shapiro-Wilk AND Levene tests indicated normality of the temperatures AND in most cases equality of temperature variances between zones, respectively. Also Games-Howell AND Gabriel tests proved that the mean maximum temperatures among the zones have significant pairwise differences in all time scales, proving the accuracy of the zonings. The mean afternoon temperature throughout the country was calculated based on the raster calculations at the rate of 25.3oC, which has been increased at the rate of 0.62oC as compared to the last 45 years.

At present, Groundwater contamination by nitrate, serves as one of the most important environmental issues. In respect to various lAND uses of Silveh basin, its ground water quality parameters might vary SPATIALly AND TEMPORALly. For this, ground water samples taken from 145 points were evaluated. After determining nitrate SPATIAL VARIATIONS by varyogram, different methods involved distance inverse method AND geo-statistics methods of radial estimator approaches, local estimator, ordinary kriging, simple kriging AND global kriging were evaluated using GIS software AND nitrate SPATIAL distribution map were prepared in two time intervals (pre AND post-harvest). Criteria based on the Root Mean Squared Error(RMSE), ordinary kriging method has the lowest error, AND the accuracy considerably. SPATIAL distribution of nitrate in area groundwater indicated that there was high concentration of nitrate in lAND uses of agriculture AND arid area. Of course, presence of shale-stone causes nitrate releases, intensifying issues. Comparison of nitrate samples concentration with national AND international stANDards suggested that 1. 38%(2 Point) of all samples have been nitrate-contaminated before harvesting, while 11. 03%(16 Point) of them have been contaminated after harvesting.