محمد جواد طوریان

In recent years, the phenomenon of climate change and drought has become a global problem in the arid and semi-arid regions of the world. Climate change as a problem in the annual bio-farming cycle causes extinction of plant and animal species, reduced vegetation richness, impaired and reduced fertility severity in animals, changes in the pattern of migration of birds and animals (due to new habitats or food sources New) and changes in the spawning pattern of fish. Droughts and floods are one of the most severe climatic events that are likely to change faster than the average climate of any region. Today, access to freshwater resources is a very important issue in most countries, including the Middle East and Iran, according to FAO statistics, while the Middle East accounts for 14 percent of the Earth's surface, accounting for only 2 percent of water resources. The drying up of internationally valuable lakes and wetlands, the lowering of rivers to crisis levels, and the exposure of people in 12 provinces to drinking water shortages are among the consequences of a nationwide drought. Droughts have been particularly prevalent in the tropical and subtropical regions since the 1970s. Reduced ground precipitation and increased temperatures, which increase evaporation and decrease soil moisture, are important factors that have led to more drought zones. Recent droughts have emphasized the need for more research into the causes and effects of droughts and the need for additional planning to help reduce the potential consequences of future droughts. On the other hand, some studies consider the increase in greenhouse gases and disruption of sunlight transfer to and from the earth to the atmosphere as a reason for the recent drought. In the present study, monthly changes of atmospheric carbon dioxide and monthly changes of total water storage in the period 2003-2015 in Iran were investigated. Combined data with the Obsm4MIPs algorithm of GOSAT satellite and SCIAMACHY sensor were used to obtain the trend of changes in carbon dioxide concentration and GRACE satellite data for changes in total water storage from 2003 to 2015. The results of the canonical correlation show a strong relationship between carbon dioxide concentration and changes in total water storage. Stepwise regression model was used to model the relationship between changes in total water storage with CO2, discharge rate and groundwater consumption. The results of regression model showed that carbon dioxide with R2 = 0.91 had the highest relationship with total water reservoir changes in the model. It is noteworthy that the identification of these relationships on a large scale is tangible and at the local scale management practices are more influential in changing water resources, especially groundwater.

Based on 11 years of TOPEX/Poseidon satellite altimetry and coastal tide gauge sea level observations, four tidal constituents, namely O1, K1, M2 and S2, are modeled for the Persian Gulf and Oman Sea using a time-wise approach according to the following details. By selecting the cycle 100 as the reference, 772 points on 12 paths along the track of the altimetry satellite footprints over the Persian Gulf and Oman Sea are selected as the center points of 772 circular cells that were used to catch the repeated MGDR data from cycle 8 through 345 that fall within the aforementioned circular cells with a radius of 0.053?. In this way 772 time series of the sea level observations located at the center of the circular cells are developed. These data were further corrected for all effects whose correction parameters are given by the MGDR data files; except the tidal correction that was kept to become the source of information for our tidal modeling. The gaps in the 772 satellite derived time series are filled via inverse solution of the autocorrelation function that was applied to the existing sea level variation data. Besides, the 1 hourly time series of sea level observations at 17 tide gauges along the Iranian coast line at the Persian Gulf and Oman Sea were used both to check the validity of the tidal models developed by the altimetry data at the 772 point over the above mentioned sea areas and to increase the accuracy of satellite derived tidal models at the shallow waters. The equally spaced 772 satellite altimetry derived time series and 17 time series at the coastal tide gauge stations are subjected to Fourier analysis to obtain the major tidal constituents, which are next used as the initial value within a least square solution to obtain the adjusted tidal frequencies, their phase angles and amplitudes. The result of this step for the satellite derived time series were modeling of all the existing tidal constituents with periods greater than 20 days, as the repetition of the TOPEX/Poseidon satellite altimetry observation is 9.915 days, except for the crossover points where the repetition time period is half. Next, via forward modeling, the effects of the modeled tidal constituents were removed from the original 772 time series to remain with the residual time series that were re-orders according to their observation hour, without considering their observation date in order to develop 2 hourly residual time series, which were used to derive the other short period tidal constituents. The result of the numerical computation and the comparison of the satellite derive models with that obtained by tide gauge observations granted the success of the method and such a new tidal model for four tidal constituents namely, O1, K1, M2 and S2 is developed for the test area, i.e. Persian Gulf and Oman Sea.