Sedimentology
Alireza Vaezi; Vahid Tavakoli; Abdolmajid Naderi-Beni
Abstract
In the present study, in order to reconstruct the paleoenvironmental and climatic changes of Jiroft during the last 4000 years, several evidences of sedimentology and biogeochemistry on a sedimentary core have been investigated. Around. 3950 cal yr BP, low values of Ti/Al, Si/Al, C/N and CPI along with ...
Read More
In the present study, in order to reconstruct the paleoenvironmental and climatic changes of Jiroft during the last 4000 years, several evidences of sedimentology and biogeochemistry on a sedimentary core have been investigated. Around. 3950 cal yr BP, low values of Ti/Al, Si/Al, C/N and CPI along with high values of δ13COM, and Paq indicate a wet period in Jiroft. evidence indicates a relative decrease in humidity between about 3900 and 3293 cal yr BP. Between 3293 and 2897 cal yr BP, Jiroft was dry and dusty. The results show very dry conditions with a significant increase in the amount of dust around 3200 cal yr BP. A long-wet period from about 2897 to 2302 cal yr BP can be recognized with high Paq values. The highest Ti/Al values along with the lowest δ13COM values indicate increased wind activity and dry conditions between 2100 and 1650 cal yr BP. Jiroft experienced wet conditions between 1540 and 1315 cal yr BP. With the relative decrease of rainfall, a semi-humid climate prevailed in Jiroft between 1315 and 854 cal yr BP.
Geophysics
safieh farrokhi mogaddam; Abbas Alli Alli akbari bidokhti; Farhang Ahmadi givi; Mojtaba Ezam
Abstract
Salinity and water temperature are considered as important characteristics of water of different seas. The absolute values and variability of them in time and space determine life sustainability conditions, development of plants and animals and also types of human activity in seas. Water temperature ...
Read More
Salinity and water temperature are considered as important characteristics of water of different seas. The absolute values and variability of them in time and space determine life sustainability conditions, development of plants and animals and also types of human activity in seas. Water temperature and salinity are important because of their effects on chemical and biochemical reactions of hydro-organisms. In this research the effects of climate change on physical characteristics of Persian Gulf including water temperature and salinity has been studied using numerical simulations and some observations. To carry out numerical simulation, the 1-dimension oceanic numerical model PROBE was used. The input data of the model includes meteorological information obtained from ECMWF and also initial values of the station. To simulate the vertical turbulence, the relations of Axcell-Liungman, Omstedt, Rodi, Pacanovski and Marchuk have been used for a station in the Persian Gulf and the results have been compared with some measurements and similar studies. The results of investigations show that limits of seawater and salinity variability model outputs are similar but the Omstedt relation shows more detailed changes in comparison to the others. The numerical results indicate that the temperature increase of the Persian Gulf over a decade can be as large as one to two degree Celsius, with some salinity increase as well.
Geological Environment and Engineering
Shahrzad Faryadi; Ali Alavi Naeini
Abstract
climate change is known as one of the most important environmental crises which has made many problems . Considering the undeniable impact of humans in the production of greenhouse gasses, in this paper the situation of the climate change of Tehran is predicted by modeling three different scenarios, ...
Read More
climate change is known as one of the most important environmental crises which has made many problems . Considering the undeniable impact of humans in the production of greenhouse gasses, in this paper the situation of the climate change of Tehran is predicted by modeling three different scenarios, for the period of 2046 until 2065. Based on optimistic, pessimistic and neither pessimistic nor optimistic scenarios, the alterations of climate parameters are forecasted. It is concluded that the amount rainfall will decrease, while, the amount of temperature will go up. To do this research the software of LARS-WG is used for modeling the climate change. This software is a sample of Meteorological generating models which is useful for simulation of climate data for now or future in an area. Then, considering the significant role of fossil fuels in deteriorating this phenomenon and determining the proportion of the effects of different modes of transportation in generating carbon, the existing policies on reduction of burning fossil fuels is investigated. At the end, based on the necessity of cooperation of people in various aspects of formulation of policies including behavioral-social and technological-technical, some suggestions are proposed to decrease the production of carbon.
Hydrology
Mostafa Naderi
Abstract
The Dorudzan dam inflow is assessed using SWAT under climate change. The daily simulated precipitation and temperature data by 22 general circulation models under RCP2.6, RCP4.5 and RCP8.5 are downscaled at five climatic stations using LARS-WG statistical model and transient change factors approach. ...
Read More
The Dorudzan dam inflow is assessed using SWAT under climate change. The daily simulated precipitation and temperature data by 22 general circulation models under RCP2.6, RCP4.5 and RCP8.5 are downscaled at five climatic stations using LARS-WG statistical model and transient change factors approach. The precipitation over the watershed will decrease from 668 mm during the observation period to 572, 509 and 529 mm under the RCP2.6, RCP4.5 and RCP8.5, respectively (14.4%, 23.8% and 20.8%). The mean annual evapotranspiration will increase by 30%-36% due to increased mean annual temperature by 1.7-3.3 ℃ under three RCPs. The mean annual inflow will decrease from 28.6 m3/s to 16.7, 11.44 and 12 m3/s under the RCP2.6, RCP4.5 and RCP8.5, respectively (42%, 60% and 58%). The mean monthly reservoir volume will decrease from 490 MCM to 350, 232 and 247 MCM under the RCP2.6, RCP4.5 and RCP8.5, respectively while the dam outflow will decrease from 60 MCM/month to 43.3, 29 and 30.9 MCM/month, respectively due to the precipitation reduction by 160 mm (24%) and evapotranspiration increase by 100 mm (36%) over the watershed. The reduction of reservoir volume will intensify the downstream water shortage and crisis in the future.
