The phenomenon of climate change in recent years has led to significant changes in climatic elements and as a result the status of surface and groundwater resources, especially in arid and semi-arid regions, this issue has sometimes caused a significant decline in groundwater resources. In this paper, the effects of climate change on the status of groundwater resources in Marvdasht plain have been investigated. Water supply of different parts of this region is highly dependent on groundwater resources and therefore the study of groundwater changes in future periods is important in the development of this plain and the management of its water resources. In order to evaluate the effects of climate change, the output of atmospheric circulation models (GCM) has been used.
Then, in order to adapt the output scale of these models to the scale required by local studies of climate change, precipitation and temperature data have been downscaled by LARS-WG model. Downscaled information was used to determine the amount of feed and drainage of the aquifer in future periods. To investigate changes in groundwater levels at different stages, a neural network dynamic model has been developed in MATLAB software environment. It is also possible to study and compare other points using other scenarios and mathematical modeling. The results of the study, assuming the current state of development in the region, indicate a downward trend in the volume of the aquifer due to climate change and its effects on resources and uses of the study area. The results also introduce Scenario A2 as the most critical scenario related to climate change, which also shows the largest aquifer decline in neural network modeling.

The hydrology section is divided into two main components, surface and groundwater. One of the most important outcomes in the water balance equation for any natural area or water body is Evapotranspiration and it is also a crucial component of the hydrologic cycle. Prediction of monthly evapotranspiration can be obtained depending on observed monthly average temperatures at a meteorological station in each year. Calculating of water balance in Iraq depending on meteorological data and Thornthwaite method was the aim of this research. Results of corrected potential evapotranspiration (PEc) obtained from applying _Thornthwaite formula_ were compared with annual and monthly rainfall in thirty two meteorological station in order to estimate actual evapotranspiration (AE). The results showed that the annual summation of rainfall increased from south west towards north east according to the increasing ratio of rainfall due to the impact of Mediterranean climate condition on Iraq. Actual evapotranspiration depends directly on water excess during calculating water balance. Water surplus contour map indicates increased values towards north-east direction of Iraq, where water surplus depends directly on both rainfall and actual evapotranspiration.

The effect of meteorological and hydrological droughts is very important in arid and semi-arid regions. So analyzing these effects on groundwater supplies play important role for managing water in those regions. Therefore, the aim of this paper is to characterize several kinds of droughts in Isfahan-Borkhar basin that is an arid area of Iran. Observed hydro-climatic data (for the period of 1971-2005) were used for hydro-meteorological projections (for the period of 2006-2040). Meteorological and surface hydrological drought evaluated by Standardized Precipitation Index (SPI), Standardized Runoff Index (SRI), and the effect of hydro- meteorological droughts on groundwater is investigated by Groundwater Resources Index (GRI). Results showed that dry and wet conditions would occur in the region in the initial and subsequent future decades, based on the three indices. There is an appropriate association between SPI, SRI, and GRI at the time scale of 12 months. The SPI estimated using only meteorological variables and better performed for meteorological drought forecasts than the SRI and GRI that computed using catchment discharge, soil moisture and groundwater level and represented hydrological drought. Results showed a considerable alteration of time of drought outlines across the area and association between the variables of predicted precipitation, temperature and the kind of indices. The projection of all three drought indices indicated drier conditions in the future period. The results provide reasonable management strategy for management of water resources in coastal plains.

In this research, the catchment area of ​​the Karkheh River has been investigated in order to investigate the relationship between the sediment and the effect of climate change on the phenomenon of microstrip. In the first step, to determine the relationship between the grains and sediments, it is necessary to determine the origin of sedimentation and its gradation. Accordingly, some sediment samples were taken from the river bed. Sediment aggregate size measurement is an important tool for studying its origin. Currently, for statistical purposes, many samples are used, but these methods are time-consuming and difficult. The size of the sediment in the study of origin, and its relationship with the micro-organisms, is an important factor. Therefore, the use of modern methods is essential. In the present study, the data of the sediment samples were introduced into the acetate gradient (statistical analysis program) to determine the texture and granulation of the sediment. The results showed that sand gravel texture is. Then sampling and testing on the microscopes showed that they are also of sandy origin, so it can be assumed that abrupt grafting of microspheres after sediment can cause sediment in the river. In addition, in order to investigate the effect of climate change on the micrographs, the relationship between three climatic parameters including rainfall, minima and relative humidity with the number of days with a rigorous refreshment for two years of 2015 and 2016 were analyzed. The results showed that, with increasing temperature and decreasing precipitation and relative humidity, the number of days with the coarse cutter increases, and as a result, it can be caused by sedimentation as part of sedimentation in the river.

The purpose of this research is to identify the heat waves of the South Sea of Iran and compare the conditions in the present and future. To reach this goal, the average daily temperature of 35 years has been used. Also, in order to predict future heat waves, the maximum temperature data of four models of the CMIP5 model series, according to the RCP 8.5 scenario, has been used for the period 2040-2074. In order to reverse the output of the climatic models, artificial neural networks were used to identify the thermal waves, and the Fumiaki index was used to determine the thermal waves. Using the programming in MATLAB software, the days when their temperature exceeded 2 standard deviations as a thermal wave were identified. The results of the research show that the short-term heat waves are more likely to occur. Heat waves in the base period have a significant but poorly developed trend, so that the frequency has increased in recent years. In the period from 2040 to 2074, the frequency of thermal waves has a significant decreasing trend, but usually with low coefficients. However, for some stations from 2040 to 2074, the frequency of predicted heat waves increased.