Evaluating sedimentation effect on reservoirs water quality: a case study,Shahriyar reservoir

In this research, total dissolved solids (TDS) was simulated by CE-QUAL-W2 software in two scenarios of with and without sedimentation in normal, dry, and wet periods of inflow for Shahriyar reservoir, an under-construction dam located in Iran. Shahriyar reservoir is a dam with a total capacity of 700 million cubic meters (MCM) and a dead volume of 360 MCM. In case of with sedimentation compared with without sedimentation, results showed an annual average increase of 4, 4.3, and 8.7% in TDS of outflow for normal, wet, and dry periods, respectively. There is no significant change in TDS profile of the reservoir in both conditions. According to the average outflow TDS of 1448, 1301, and 1555 mg/L compared with the average inflow TDS of 1714, 1520, and 1835 in normal, wet, and dry conditions, respectively, the effect of dam on inflow TDS adjustment can be also observed. With the mentioned outflow TDS, there is no limitation to use of reservoir water for agricultural purposes based on FAO irrigation guidelines for both scenarios.     

Tectono‐sedimentary evolution of the northern Iranian Plateau: insights from middle–late Miocene foreland‐basin deposits

Sedimentary basins in the interior of orogenic plateaus can provide unique insights into the early history of plateau evolution and related geodynamic processes. The northern sectors of the Iranian Plateau of the Arabia–Eurasia collision zone offer the unique possibility to study middle–late Miocene terrestrial clastic and volcaniclastic sediments that allow assessing the nascent stages of collisional plateau formation. In particular, these sedimentary archives allow investigating several debated and poorly understood issues associated with the long‐term evolution of the Iranian Plateau, including the regional spatio‐temporal characteristics of sedimentation and deformation and the mechanisms of plateau growth. We document that middle–late Miocene crustal shortening and thickening processes led to the growth of a basement‐cored range (Takab Range Complex) in the interior of the plateau. This triggered the development of a foreland‐basin (Great Pari Basin) to the east between 16.5 and 10.7 Ma. By 10.7 Ma, a fast progradation of conglomerates over the foreland strata occurred, most likely during a decrease in flexural subsidence triggered by rock uplift along an intraforeland basement‐cored range (Mahneshan Range Complex). This was in turn followed by the final incorporation of the foreland deposits into the orogenic system and ensuing compartmentalization of the formerly contiguous foreland into several intermontane basins. Overall, our data suggest that shortening and thickening processes led to the outward and vertical growth of the northern sectors of the Iranian Plateau starting from the middle Miocene. This implies that mantle‐flow processes may have had a limited contribution toward building the Iranian Plateau in NW Iran.     

Modeling the near-field effects of the worst-case tsunami in the Makran subduction zone

As a first step towards the development of inundation maps for the northwestern Indian Ocean, we simulated the near-field inundation of two large tsunami in the Makran subduction zone (MSZ). The tsunami scenarios were based on large historical earthquakes in the region. The first scenario included the rupture of about 500 km of the plate boundary in the eastern MSZ, featuring a moment magnitude of M_w 8.6. The second scenario involved the full rupture of the plate boundary resulting from a M_w 9 earthquake. For each scenario, the distribution of tsunami wave height along the coastlines of the region is presented. Also, detailed runup modeling was performed at four main coastal cities in the region for the second scenario. To investigate the possible effect of splay fault branching on tsunami wave height, a hypothetical splay fault was modeled which showed that it can locally increase the maximum wave height by a factor of 2. Our results showed that the two tsunami scenarios produce a runup height of 12-18 m and 24-30 m, respectively. For the second scenario, the modeled inundation distance was between 1 and 5 km.