In various researches, implementation of Meteorological parameters in Drought prediction is studied. In the current work, Meteorological Drought classes based on Standardized Precipitation Index (SPI) for six seasonal scenarios (autumn, winter, spring, autumn +winter, winter +spring, and autumn +winter +spring) and Meteorological predictors contained ground and sea surface temperature, weather temperature (at 300, 500, 700 and 850 mi bar) and geopotential height (at 300, 500, 700 and 850 mi bar) wide of North (0, 60) and East (0, 90) was applied in prediction models based on data from 1975 to 2005. In these models, temporal range of Meteorological predictors is between Octobers to April month on the same predicted SPI. SPI was calculated based on mean precipitation at seasonal time scale in the main watershed of Tehran (Taleghan, Mamloo) by verse Weighted Distance method. The well-known statistical supervised machine learning method, support vector machine (SVM), is applied to predict SPI. Regarding to selected data points, the effective regions on Tehran precipitation are southern, southwestern and northwestern of Iran in spring, northern and northwestern in autumn and northwestern and western in winter. SVM depicted accurate results in prediction of SPI, spatially prediction of SPI in all scenarios, and it can be proposed as a very suitable statistical learning method in investigating of nonlinear behavior of Meteorological phenomena with a short samples. The predicted SPI in spring and autumn are more accurate than the other scenarios. 

Extended Abstract Introduction: The occurrence of Droughts in a region is closely related to water supply. Since water supply in each region is related to the climatic regime of that area, so the definition of Droughts varies according to the conditions of each region. Drought can be attributed to a period of abnormally dry conditions that is sufficiently long to produce an imbalance in the hydrologic state of an area. Monitoring systems play an important role in the management of Drought plans. The beginning of Droughts is due to the occurrence of the Meteorological Drought caused by the precipitation shortages. The hydrological Droughts are usually more delayed than the Meteorological or agricultural Droughts. ...

Water crisis and Drought are among the most important issues to which the human has been faced particularly in the recent years; hence, investigation of Drought is so important in optimal water management. Drought has been known as an environmental phenomenon which is inseparable from climate changes which can occur in any geographical region. Various definitions have been presented since yet. By a general definition, Drought includes abnormal shortage of precipitation in a long-term period so that, it causes soil moisture shortage and reduced current waters; therefore, human activities and natural life of plants are disturbed. Qarehsou watershed is among the places which are affected by Drought issue. Considering the major role of this watershed on water supply of Kermanshah Province as well as recreational value of Qarehsou River; the occurred Droughts can cause economic challenges and ultimately, social crisis in the region. The objective of the present study is to determine Meteorological and hydrological wet and Drought periods and investigating the relationship between them of which the results can be used for more appropriate water resources management in Qarehsou watershed. In the present study, the statistics of five rain-gauge stations, five hydrometric and 20 piezometric wells existing in the watershed were used for Drought analysis. Drought indices RAI and SIAP were used to extract Meteorological Drought periods and also the indices SDI and SWI were used to analyze hydrological Drought. According to the obtained amounts by each Drought indices, the severest Drought has occurred in 2007; hence, the hydrological and Meteorological Drought zoning maps of the year 2007-2008 were drawn. The results showed that, the Drought severity has been increased gradually since 1999 and the severest Drought was in 2007 and the most durable one has occurred during 2007 to 2012.The results indicated that, hydrological Drought has been occurred since the cropping season 2007-2008 with one-year delay relative to Meteorological Drought. Also during the recent years, one or two years of delay has been observed between the occurrence of hydrological Drought of underground waters and Meteorological Drought. The results demonstrated that, based on the index RAI, the maximum frequency was related to the stations Mahidasht, Pol Kohneh and Ravansar by 27% at a very severe Drought class. Also based on the index SIAP, the maximum frequency was related to the station Doabmerk by 23% at a moderate Drought class. Based on the index SDI, the maximum frequency was in the station Sarasiab by 45% at a moderate Drought class and finally, based on the index SWI, the maximum frequency was related to the piezometric wells of Hashilan, QarehTapeh and Kahriz by 45% at a moderate Drought class. Zoning maps of Meteorological Drought showed that, Meteorological Drought has occurred in all the region. According to the zoning map of hydrological Drought, hydrological Drought of the surface flows is at a moderate class throughout the watershed while, hydrological Drought of the underground water resources at the north east and south west and somewhat central parts of the watershed is at a very severe class. Generally, results of the present study indicated that, duration and severity of the Droughts and particularly hydrological Drought are considerable during the recent years in QarehSou watershed. Hence, results of the present study can be useful for optimal management of water resources and water demand and supply planning, as well as the managers, lanners and experts who can be enabled to provide required strategies and practical solutions.

Drought is a natural disaster which could be repeated, and cause damages in all climates. In Iran, Drought has occurred frequently and caused water shortages in different sectors. Fars province geographical location is in the western sought of Iran. Due to the increases cities, villages, industrial and agricultural centers in this province, Drought assessment is an urgent need. In this research Z score, Percentage of Normal Precipitation Index (PNPI), Decades of Precipitation Index (DPI), Rainfall Anomaly Index (RAI) and standard precipitation Index (SPI) were evaluated and and compared. Statistical analysis of precipitation showed a stable condition in Doroudzan Dam station and unstable conditions in Lar, Lamerd and Abadeh. Precipitation had a wide variation except in Shiraz, Zarghan and Doroudzan Dam stations, which verifies dominant Drought climates in Fars. In order to determine the best index, minimum of rainfall and indicies correlation were used in this study. Results showed that PNPI-Z ,PNPI-SPI SPI-RAI, SPI-Z RAI-Z and PNPI-RAI indices are the most correlated ones, and DPI-SPI , DPI-RAI ,DPI-Z ,DPI-PNPI indices have week correlation. 1 and 12 months average indices showed the most correlation. The results showed that the PNPI, SPI and Z coincided with the date of minimal rainfall, and reported a severe Drought in the study stations, therefore they are more efficient than the other indices to determine Meteorological Drought.

Drought is caused decrease by of rainfall, runoff and soil moisture and also increase of air temperature and water table compared to long time average condition. Drought can be divided into four major groups of Meteorological, Hydrological, Agricultural and Social- economical which Meteorological Drought will be evaluated by rainfall values comparing with its average. In this study, by use of monthly rainfall data of Babolsar, Noushahr and Ramsar synoptic Stations which are related to Mazandaran Meteorological Organization, Drought events was quantified by Standardized Precipitation Index (SPI), Percentage of Normal Index (PNI), Deciles Index (DI), Chinese Z Index (CZI), Modified Chinese Z Index (MCZI) and Z- Score Index and Mohan & Rangacharia method. Results shows that PNI and DI in all stations have similar trends and the Curves of SPI, ZSI and CZI in all stations are well coincide with each other and have a very good fitness but MCZI.In Mohan & Rangacharia method, Drought events characteristics consists of commencement, termination, duration and intensity were determined for all stations. Applying this method for preparing iso-duration and iso- intensity maps of Drought (Drought zoning) for determination of the Drought susceptible area and also forecasting the future condition are recommended.

If the occurrence of some climatic elements especially rainfall at a given time is less than normal and long term condition, the region will encounter Drought. The evaluation of Drought in each region needs the quantification of Drought. Although none of the indices is superior compared to the others some indices could be more suitable for some users. For this reason, the results of all indices could be different. Main indices investigated in this research were as follows: SIAP, DPI, Z index, PNPI, SPI. The mentioned indices were evaluated using the data of 15 synoptic stations of Hamedan during 20 years, and the best methods were determined. Then, based on that, the map of Drought and wet conditions of the province was produced. According to the results, SIAP and Z SCORE were identified as the best compared to the other methods and they could be considered as main indices in the evaluation of Drought in Hamedan province.

Drought as a natural hazard has always affected some parts of the country. Nowadays, it is possible to study Drought using remote sensing techniques through its effects on the plants and achieve more accurate and efficient results for Drought modelling. This study aims to investigate the relationship between Meteorological, hydrological and agricultural Drought using Drought indices and remote sensing method in Gharehsou watershed. For this purpose, MODIS images (satellite Terra, product MODO9Q1) and rainfall and discharge data of five Meteorological and hydrometric stations for 2000 to 2015 time period were used. The results of the comparison of Meteorological, hydrological and agricultural Drought represent conformity of the three types of Drought in the years 2000, 2001, 2004, 2005, 2007, 2009, 2010, 2011, 2012, 2013, 2014 and 2015. Although the SPI and NDVI values were positive in the years 2002, 2003 and 2008, SDI index showed the occurrence of hydrological Drought (negative values). In the year 2006 despite the rainfall increase, but this year has been facing the agricultural and hydrological Drought. So the results simultaneity of Drought there does not exist in all the years. The results of Pearson correlation showed there is a high correlation between mean NDVI and SPI and SDI indices equal to 0.706 and 0.788 respectively at the significance level of 0.01. Generally, the results of SDI and SPI indices largely confirm the results of the NDVI index.

Drought is a natural phenomenon that occurs as a result of a decrease in the amount of precipitation in a period of time, compared to the normal or expected amount in the same period of time. Irregularity of Meteorological variables, including the precipitation with a long periodicity, is affected by the phenomena that occur all over the earth with different periodicity and are known as Meteorological signals. Teleconnections are a category of Meteorological signals. Teleconnection refers to two regions on the surface of the earth that have a high correlation with each other in terms of climate. In addition, some low-frequency events (with long periodicity) in tropical regions also affect atmospheric patterns in higher latitudes. Since the amount of precipitation has a direct effect on recharging the aquifers, the prolongation of the Drought period due to teleconnection patterns can also affect the groundwater level. Investigating the effects of the teleconnection patterns and predicting them, especially during Drought periods, will be a great help for more accurate planning and management of the watershed. Since teleconnection patterns are in the category of large-scale phenomena, it is expected that the areas affected by them will be very vast. In most of the conducted studies, the relationship between Drought indices and these phenomena has been done at station points. Considering the effect of local factors on the phenomenon of precipitation, point analysis can increase the uncertainty in the results. In this study, the regional average of precipitation in Chaharmahal and Bakhtiari provinces was used to calculate the Drought index and to investigate its relationship with the groundwater level. Also, in order to study the role of teleconnection phenomena in creating Meteorological and hydrological (groundwater) Droughts in Faradonbeh and Sefiddasht plains, the relationship between the indicators of several well-known teleconnection patterns and Meteorological and hydrological (groundwater) Droughts has been investigated. Methods: In order to study the Meteorological Drought, the monthly precipitation data of the synoptic stations of Chaharmahal and Bakhtiari province from 2000 to 2020 were used. Also, the water level measured at 19 observation wells were used to investigate the groundwater Drought of the Faradonbeh and Sefiddasht plains. The Standardized Precipitation Index (SPI) and the Groundwater Resource Index (GRI) were applied to monitor the Meteorological and groundwater Droughts of the Faradonbeh and Sefiddasht plains, respectively. Since the stations in the study area do not have the same distribution and each station has a different effect area, the average precipitation of the Chaharmahal and Bakhtiari province was calculated by weighted average method (based on area and distance) and the regional monthly precipitation time series was used to calculate the SPI index. Also, the values of teleconnection indicators including Madden-Julian Oscillation (MJO), El Nino-Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD) for the period of 1991-2021 were downloaded from the website of The National Center for Atmospheric Research and the National Center for Environmental Prediction (NCEP/NCAR). Since teleconnection phenomena have two positive and negative phases, to investigate the relationship between Meteorological and groundwater Drought indices with these phenomena, the correlation between SPI and GRI with teleconnection indicators has been done in several cases: Simultaneous correlation of data (correlation between all data), correlation in positive and negative phases of each teleconnection pattern (only positive phases or negative phase of teleconnection indicators were considered), calculation of correlation in each season (based on the solar calendar) separately, removing 5 dry months of the year (June to October) and calculating the correlation with a delay of one month. Results: The results showed that the NAO and IOD indices have the highest correlation with precipitation and SPI index, and have had the greatest impact on precipitation and Drought in the study area. Also, the IOD and ENSO indices have a negative and inverse correlation with the GRI index. In general, it can be concluded that the difference in the response time of Meteorological and groundwater Droughts has a direct role in the extent of its influence from teleconnection events. So that the NAO phenomenon, which has a shorter periodicity than El Nino and IOD, is more significantly related to Meteorological Drought, which has a shorter response time, and hydrological Drought, which has a longer response time, is more affected by El Nino teleconnection, which has a longer periodicity. The MJO phenomenon, which has the shortest periodicity among the studied teleconnection phenomena, had no significant relationship with the Droughts of these plains.

Introduction Drought is known as one of the environmental phenomena and it is also considered as a direct impact of climatic changes that can occur in any geographical area. Materials and Methods In this study, monthly and annual rainfall data of 17 rain gauge stations belonging to the Meteorological Organization from 1972 to 2017 in Guilan Province have been used to investigate the severity, duration, and extent of Drought. To evaluate and compare the capabilities of Meteorological and hydrological Drought, the standardized precipitation index (SPI) and streamflow Drought index (SDI) were calculated (Lui et al., 2012) for the whole province in the periods of three, six, nine, 12-month, and annual scale depending on the capability of the index, severity, and duration of Drought spells. Results and Discussion To investigate the extent of Drought, zoning maps were prepared using the inverse distance weighting method. According to statistics and information obtained from a statistical period from 1972 to 2017, the amount of the three-month SPI index is determined as a wet period. The results of Drought severity zoning in Guilan Province showed that the SPI values in six, nine, and 12-month time scales were categorized as dry periods. In most of the cities of the study province, the Drought was observed with the highest probability and had positive changes in the area of Drought extent. Conclusion The maps obtained from SPI interpolating in four statistical periods showed that the value of standardized precipitation index has increased in 2017 compared with 1972, and most cities in the studied province are covered by more Drought-prone areas. In addition, the main Drought in the region is observed in the Meteorological stations located in the south and southeast of the region. According to the SDI values, it can be concluded that most of the river gauge stations are without or with moderate Drought.

Extended Abstract Introduction Drought is a weather phenomenon that causes much damage every year. Kohgilouyeh and Boyer Ahmad province is located in the Southwest of Iran. Since it provides a substantial portion of the water of Karoun, Maroon, and Zohreh, which are three important rivers in this province, and evaluation and prediction of Drought in this province seems necessary. This study aims to evaluate the compliance of Meteorological and hydrological Drought of the Zohreh river basin is in this province. Materials and methods: Using SPI (Standardized Precipitation Index) and SWI index (Standardized Water level Indicator), the relationship between Meteorological and hydrological Drought was evaluated, and the comparison between the occurrence of Meteorological and hydrological Droughts was performed. The SPI was calculated for 10 Meteorological stations with 30 years of data, and SWI for 11 piezometric wells for the whole statistical data available. The trend of the river streamflow and piezometric wells' groundwater levels was assessed using the Mann-Kendall test for 5 hydrometric stations and the piezometric wells. The Pearson correlation coefficient was used to assess the relationship between rainfall, discharge, and groundwater level in different time lags. Results and Discussion: Results showed that in negative SPI durations, the groundwater level decreased with some delay. The delay increased when the Drought scale increased. In recent years, the duration and intensity of Drought have increased. Maximum volume of 3, 6, 9, and 12 months precipitation Drought of Nazmakan station occurred in 1378-78, the maximum intensity of 3, 6, and 9 months in 1383, and 12 months occurred in 1388. When the Drought scale increased, Drought duration and intensity increased, and the Drought frequency decreased. Results for the other stations were nearly similar. SWI of Basht well showed that 6, 12, 24, and 48 months Droughts continued nearly 48 months, from the end of 2006 to the middle of 2010. The intensity of 48 months Drought was maximum and 12, 24, and 6 months were in the next level of intensity. This trend shows the long time accumulating effect of Meteorological trends on the decreasing level of groundwater, although pumping withdrawal of groundwater is also effective. The trend for other wells was nearly similar. The Mann-Kendall test did not confirm the trend of stations discharge, but the decreasing level of groundwater in all wells was statistically confirmed. The Pearson’s coefficient of precipitation-discharge showed the maximum correlation with the same month data. It could be from the surface water's direct relation with groundwater, and the decreasing amount of snow precipitation in recent years, which lead to a delay between them. The maximum Pearson’s correlation of the groundwater level-precipitation, and groundwater level-discharge was observed with two months delay. It could verify the groundwater recharge with surface water, and the time needed for infiltration and movement of water in the aquifer. Conclusions: The results could be used for predicting the effects of Meteorological Drought on hydrological Drought. The properties of Meteorological and hydrological Droughts could be used to manage Drought and water resources, supply water for agriculture, industry, and livestock, and supply drinking water for humans in the province.