Iran, due to its geographical location, has low rainfall and is considered a dry land. As a result, different regions of the country grapple with DROUGHT. The presence of water management systems, such as aqueducts and reservoirs, in most parts of the country, along with a variety of methods for conserving water for irrigation, may contribute to this claim. Considering that DROUGHT is an inherent phenomenon in Iran's climate, people have invented and used numerous methods to combat it and store water. The aim of this study is to monitor and evaluate DROUGHT in Iran. In order to realize this goal, precipitation data from synoptic, rain gauge, and climatology stations were extracted over a 51-year period, from 1970 to 2020. The results obtained from examining DROUGHT occurrences in five ten-year periods reveal that, with the exception of the third decade (1991 to 2000), DROUGHT has prevailed in the majority of Iran's regions compared to other decades. On the other hand, in the recent decades leading to 2020, the intensity of DROUGHT occurrences, especially in the Middle Zagros, has intensified, which has consistently been among the regions with the highest rainfall in Iran after the Caspian region. This situation can cause concern in Iran, a country where its agricultural production hub is established along the Zagros mountain range. Moreover, the fluctuating behavior of Iran's DROUGHTs, with return periods of 2 to 5 years, has complicated the management strategies for these types of hazards. These conditions appear to have created numerous issues in many areas of Iran, particularly in the agricultural sector of the western provinces, due to the lack of conformity with these types of occurrences.

DROUGHT is a consequence of fluctuations of climatic conditions. Scientific investigation of DROUGHT is essential for water resources planning and management and to mitigate water shortages. DROUGHT analyses were done just by some quality factors during the last few decades, but currently there are several mathematical DROUGHT indices. In this research the Standardized Precipitation Index (SPI) was used for analysing and MONITORING climatological DROUGHT in Golestan Province. For this purpose, monthly rainfall statistical data of 24 gagging stations for 29 years periods were used. The DROUGHT status maps were then prepared by using Surfer 8.0 software, for all years. The results showed very high DROUGHT fluctuations. Despite finding any clear cycle for DROUGHT occurrence, it can be obviously showed that the major DROUGHT or wet conditions can occur roughly every 11 years. There can some DROUGHT and wet years be observed even during those 11 years. DROUGHT occurrence and frequency was found very high in the border parts of the province and also near the Caspian see beach. These regions are located in dry and semi-dry climate. Moreover, the exact time in which DROUGHT begins and ends are not the same in all the regions. Furthermore, there can be at least 3 humidity conditions every year.

DROUGHT is one of the major natural disasters which affect human society more than all other calamities. In order to monitor the DROUGHT conditions in Nahavand City, the province of Hamedan, the monthly and annual rainfall data of the Varayeneh and Vasaj Stations were collected for 41 years (1969-2009). The DROUGHT condition were analyzed using Rainfall Anomaly Index (RAI), Standard Index of Annual Precipitation (SLAP), Percentage of Normal Index (PNI), Deciles Index (DI), Standardized Precipitation Index (SPI), Chinese Z Index (CZI), Modified CZI (MCZI) and Z Score Index (ZSI). The results indicate that the most severe DROUGHT recorded at both the Varayeneh and Vasaj stations based on the PNI, SPI, CZI, DI and ZSI indices in the water year of 1998-1999. According to the MCZI index, a severe DROUGHT, was observed at both the Vasaj and Varayeneh stations in the water year of 1970-1971. Based on SLAP index, five severe DROUGHT cases were observed at the Varayeneh station, and seven severe DROUGHT cases were observed at the Vasaj station. Based on the RAI index, five severe DROUGHTs were observed at the Varayeneh station and seven severe DROUGHTs were observed at the Vasaj station. Moreover, based on the majority of these indices, the most severe DROUGHT of this 40-year period in Nahavand City occurred in the water year of 1998-1999.

The aim of this study is to link DROUGHT MONITORING systems to management actions in surface water systems. For this purpose DROUGHT early warning system is applied. In order to assess the proposed approach, water resources system of Zarine-rud River and Reservoir was used. Management actions includes utilizing coefficients that decrease the release from the reservoir. In each DROUGHT warning level, a reduction coefficient is computed by a Multi-Objective Genetic Algorithm. Utilizing the model during the entire historic period, the number of alerts is decreased on levels two to four by 18, 80, and 10%, respectively. Also, by applying reduction coefficients during index DROUGHT period, deficits above 80% decreased to less than 50% over six months. The effect of model in condition of supplying the environment water right of Urmia Lake is also evaluated. Applying reduction coefficients during index DROUGHT, the deficits above 50% is decreased to less than 30% over 14 months. This research showed that model had an appropriate function in warning declaration in long term periods. The assessments indicated the achieved results from the model are accurate and acceptable and therefore the application of this method is recommended.

DROUGHT is a climatological hazard and is a part of the climate of a region. This climatological phenomenon has some properties that distinguish it from other natural disasters. DROUGHT is a gradual phenomenon and when the amount of moisture and precipitation become less than normal value in a certain period, its damages are non- structural in this condition and it is said that DROUGHT has occurred. Researches show that DROUGHT damages are the highest among natural disasters. Therefore the extensive MONITORING or creating an early warning system in the DROUGHT prone area is inevitable. One of the basic instruments of DROUGHT MONITORING is the application of its index. In this paper Palmer DROUGHT Severity Index (PDSI) has been assessed as a valid and applicable model. The PDSI uses temperature (T), precipitation (P) and available water holding capacity (AWC) of the soil. Using these data for each period, potential amount of evapotranspiration is calculated based on two layer model for soil moisture computations. Then, other parameters such as potential of recharge and potential of runoff are being calculated. Finally the model output results which are monthly deviation moisture (Z) and DROUGHT severity index (X3i) have been determined to use designed software for mashed synoptic station for the statistical period (1971-2003).

DROUGHT is a climate phenomenon with a lack of moisture and rainfall compared to normal conditions. This phenomenon strongly affects all aspects of human activity. In this Article, were discussed the DROUGHT situation in Urmia Lake using MATLAB software and system capabilities combined indicators SEPI on two-time scales 6 and 12 months. Therefore was used climate data of temperature and precipitation for 5 synoptic stations basin of Lake Urmia (Tabriz, Maragheh, Urmia, Saghez, and Mahabad). Results indicated that SEPI index show features of SPI and SEPI index. As well as it enters temperatures as a powerful factor in the DROUGHT severity in order to the investigation of the DROUGHT conditions; So SEPI DROUGHT index is better than the SPI for the study of DROUGHT.DROUGHT studies on SEPI index indicated that DROUGHT trend in Urmia Lake Basin is increasing. The temperature has an increasing trend with more intensity. The longest duration of DROUGHT in the basin of Lake Urmia is in Urmia station on a scale of 6 months from May 2005 to November 2006 for 19 months. The highest percentage of DROUGHT observed in Urmia and the lowest percentage in Mahabad stations.