With respect to the necessity of comprehensive studies on drought and also high damages that caused by drought, this research studied the meteorological and hydrological droughts. In this study, Lighvan, Navroud and Seqez basins with different climates were selected. We used monthly data of stream flow, precipitation and evaporation from 1992 to 2016 for the study of drought phenomena. The aim at this study is to analyze the SPI and SPEI for determination of dry and wet meteorological periods and use of the SSI for the exploration of hydrological drought. The analysis of drought characteristics such as intensity and duration in three areas with different climates shows that the climate change has a major impact on the characteristics of the droughts. The relations between the duration and severity of drought have been more accurate in the period of 9 months in the Navroud watershed basin. The most significant events are SPI-9 with the duration of 57 months and the severity of 34.7, SPEI-9 with the duration of 34 months and the severity of 28.09 and SSI-9 with the duration of 41 months and the severity of 30.2. According to the obtained equations in different time periods, it was resulted that the highest accuracy was observed in the relationship between the meteorological and hydrological drought characteristics in the watershed basin of Seqez for a period of 6 months. The results show that in all three basins, the correlation between the meteorological and hydrological drought is significant at the level of 99%. Results show that hydrological and meteorological droughts in Navroud and Lighvan basins have a significant correlation with 48-month periods and in the Seqez basin with 12- and 24-month periods, and the relations between hydrological droughts and meteorological droughts were obtained using the nonlinear linear models (polynomial, exponential and logarithmic). The good R² between the duration and severity of SPI-9 and SSI-9 is 0.8 and 0.92, respectively, for polynomial equations. The maximum determination coefficient of duration and severity of SPEI-9 and SSI-9 is 0.72 and 0.82, respectively, using polynomial equation. The application of several indices indicating different components of the hydrological cycle integrates many factors that affect and trigger droughts, and thus can help in providing a wider realization of the characteristics of droughts on various water sections.

考虑到全面研究干旱的必要性以及干旱造成的高破坏，本研究研究了气象和水文干旱。在这项研究中，选择了具有不同气候的Lighvan，Navroud和Seqez盆地。我们使用1992年至2016年的月流量，降水量和蒸发量的月度数据来研究干旱现象。这项研究的目的是分析SPI和SPEI，以确定干燥和潮湿的气象时期，并使用SSI进行水文干旱勘探。对三个气候不同地区的干旱特征（如强度和持续时间）的分析表明，气候变化对干旱特征具有重大影响。在纳夫鲁德流域，干旱持续时间与严重程度之间的关系在9个月内更为准确。最重要的事件是SPI-9，持续时间为57个月，严重性为34.7，SPEI-9，持续时间为34个月，严重性为28.09，严重程度为SSI-9，持续时间为41个月，严重性为30.2。根据在不同时间段获得的方程，结果表明，在6个月的时间里，Seqez流域盆地的气象和水文干旱特征之间的关系观测到了最高的准确度。结果表明，在这三个流域，气象干旱与水文干旱之间的相关性均达到99％。结果表明，纳夫鲁德盆地和利格文盆地的水文和气象干旱与48个月周期和塞奎兹盆地的12个月和24个月周期有显着相关性，并使用非线性线性关系得出了水文干旱与气象干旱之间的关系。模型（多项式，指数和对数）。好的对于多项式方程，SPI-9和SSI-9的持续时间和严重性之间的R ²分别为0.8和0.92。使用多项式方程，SPEI-9和SSI-9的持续时间和严重性的最大确定系数分别为0.72和0.82。指示水文循环不同组成部分的多个指标的应用综合了许多影响和引发干旱的因素，因此可以帮助更广泛地了解各个水域的干旱特征。