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After precipitation, reference evapotranspiration (ET O ) plays a crucial role in the hydrological cycle as it quantifies water loss. ET O significantly impacts the water balance and holds great importance at the basin level because of the spatial distribution of managing water resources. Large scale teleconnection indices (LSTIs) play a vital role by influencing climatic variables and can be pivotal in determining ET O and its predictive variables. This study aimed to model and forecast annual ET O in Iran’s basins by utilizing LSTIs and employing various machine learning models (MLMs) such as least squares support vector machine, generalized regression neural network, multi-linear regression (MLR), and multi-layer perceptron (MLP). Initially, climate data from 122 synoptic stations covering six and 30, main and sub basins were collected, and annual ET O values were computed using the Food and Agriculture Organization 56 (PMF 56) Penman–Monteith equation. The correlations between these values and 37 LSTIs were examined within lead times ranging from 7 to 12 months. Through a stepwise approach, the most influential predictor indices (LSTIs) were selected as input datasets for the MLMs. The findings revealed the significant influence of factors such as carbon dioxide (CO 2 ), Atlantic multidecadal oscillation, Atlantic Meridional Mode, and East Atlantic on annual ET O . Overall, all MLMs performed well in terms of the Scatter Index during both training and testing phases across all sub-basins. Furthermore, the MLP and MLR models displayed superior performance compared to other models in the training and testing evaluations based on various assessment metrics.

Modeling the hydrologic responses to future changes of climate is important for improving adaptive water management. In the present application to the Zarrine River Basin (ZRB), with the major reach being the main inflow source of Lake Urmia (LU), firstly future daily temperatures and precipitation are predicted using two statistical downscaling methods: the classical statistical downscaling model (SDSM), augmented by a trend-preserving bias correction, and a two-step updated quantile mapping (QM) method. The general circulation models (GCM) input to SDSM are climate predictors of the Canadian Earth System Model (CanESM2) GCM under the representative concentration pathway (RCP) emission scenarios, RCP45 and RCP85, whereas that to the QM is provided by the most suitable of several Climate Model Intercomparison Project Phase 5 (CMIP5) GCMs under RCP60, in addition. The performances of the two downscaling methods are compared to each other for a past “future” period (2006–2016) and the QM is found to be better and so is selected in the subsequent ZR streamflow simulations by means of the Soil and Water Assessment Tool (SWAT) hydrological model, calibrated and validated for the reference period (1991–2012). The impacts of climate change on the hydrologic response of the river basin, specifically the inflow to the Boukan Reservoir, the reservoir-dependable water release (DWR), are then compared for the three RCPs in the near- (2020–2038), middle- (2050–2068) and far- (2080–2098) future periods assuming (1) the “current” consumptive demand to be continued in the future, and (2) a more conservative “recommended” demand. A systematic future shortage of the available water is obtained for case (1) which can be mitigated somewhat for (2). Finally, the SWAT-predicted ZRB outflow is compared with the Montana-based estimated environmental flow of the ZR. The latter can successfully be sustained at good and fair levels for the near- and middle-future periods, but not so for the summer months of the far-future period, particularly, for RCP85.

Palynological analysis of the Shishtu 2 Member (Shishtu Formation) located in the Howz-e-Dorah area (southeast Tabas, central Iran Basin) suggests a middle Tournaisian—late Viséan age for this rock unit. The Shishtu 2 Member consists of shale, sandstone, dolostone and limestone. Three palynological assemblages are recognised and mainly correlated with the miospore biozones of Northern Gondwana. A microfloristic comparison with other sections in Western Gondwana (South America) is also proposed. We identify a sedimentary hiatus between the Shishtu 1 and Shishtu 2 members. Our findings suggest that the Mush Horizon is the lowermost part of the Shishtu 2 Member, contrary to the Iranian literature where it is considered to be the uppermost part of the Shishtu 1 Member.

The present study attempts to investigate potential impacts of climate change on floods frequency in Bazoft Basin which is located in central part of Iran. A combination of four general circulation models is used through a weighting approach to assess uncertainty in the climate projections. LARS-WG model is applied to downscale large scale atmospheric data to local stations. The resulting data is in turn used as input of the hydrological model Water and Energy Transfer between Soil, plants and atmosphere (WetSpa) to simulate runoff for present (1971–2000), near future (2020–2049) and far future (2071–2100) conditions. Results demonstrate good performance of both WetSpa and LARS-WG models. In addition in this paper instantaneous peak flow (IPF) is estimated using some empirical equations including Fuller, Sangal and Fill–Steiner methods. Comparison of estimated and observed IPF shows that Fill–Steiner is better than other methods. Then different probability distribution functions are fit to IPF series. Results of flood frequency analysis indicate that Pearson III is the best distribution fitted to IPF data. It is also indicated that flood magnitude will decrease in future for all return periods.

The Permian Jamal Formation characterized as one of the most significant successions in the Central Iran basin and constitutes a thick section (as much as 180 m) of limestone, dolomitic limestone, and dolomite in southeastern Kharu village in Tang-e Sarve area. The facies analysis of Jamal Formation leads to the identification of 11 microfacies, which are attributable to shoal, lagoon, and tidal flat environments. Results from petrographic evidence as well as facies analysis demonstrate that the depositional environment of Jamal Formation in the studied area (Kharu village, East Tabas) exhibits the characteristics of a homoclinal carbonate ramp platform with the gentle slope. This platform is mainly composed of tidal flat, lagoon, and shoal sub-environments. According to facies frequency analysis, the lagoon environment accounts for the highest abundance of facies (48%), whereas tidal flat environment shows the least abundance (17%). Bioturbation, micritization, cementation, dolomitization, neomorphism, physical and chemical compaction, and fracturing are the most important diagenetic features.

This assessment of the article by Aria-Nasab et al. (2016), on the palynostratigraphy of the upper part of the Shishtu Formation (Shishtu 2) in central Iran, reveals many shortcomings. The majority of the defects are judged to reflect unwarranted or erroneous taxonomic identifications of the adversely preserved miospores. This, in turn, casts considerable doubt on the compositional integrity of Aria-Nasab et al.'s three proposed stratigraphically successive miospore assemblages, which they dated as encompassing the mid Tournaisian through late Viséan; i.e. within the generalised Mississippian age for Shishtu 2 that had previously been established from marine faunal evidence. We confirm, through examination of their illustrations, the presence of recycled Late Devonian palynomorphs, including Retispora lepidophyta. A late Tournaisian through late Viséan or early Serpukhovian age for the sampled Shishtu 2 section is suggested here.

Groundwater quality in five catchment areas in Isfahan province of Iran is assessed by measuring physicochemical parameters including major cation and anion compositions, pH, total dissolved solid, electrical conductivity and total hardness. For this purpose, 567 piezometric well samples were collected in October 2007. The abundance of major ions in four of the catchment areas including Gavkhuni, Ardestan, Salt lake and Central Iran desert basins is similar and follows Cl −  > SO 4 2−  > Na +  > HCO 3 −  > Ca 2+  > Mg 2+  > K +  > CO 3 2− trend, while in the fifth basin (Karoon), the trend changes into HCO 3 −  > Ca 2+  > Cl −  > SO 4 2−  > Mg 2+  > Na +  > K +  >CO 3 2− . In general, four water facies are determined and it is shown that alkali elements and strong acids are dominating over alkaline earth and weak acids. Statistical analysis including Mann–Whitney U test indicate that physicochemical parameters in three of the five investigated basins [Gavkhuni, Ardestan and Central Iran desert (CID)] are similar, while Karoon and salt lake basins display different characteristics. The result indicate that groundwater west of the province is suitable for irrigation, while in the central and eastern parts of the province the groundwater loses its quality for this purpose. It is concluded that mineral dissolution and evapotranspiration are the main processes that determine major ion compositions.

Formerly the Turkmenian stone loach was the only member of the genus Metaschistura based on osteological characters. But recently, it is placed in the genus Paraschistura based on mtDNA COI data. To provide a detailed description of the osteological characteristics of Paraschistura cristata (Berg 1898), ten specimens of P. cristata were collected from the Hari River basin in Iran and their osteological characteristics were examined. According to the results, P. cristata is osteologically characterized by a foramen in the ventral part of the exoccipital, two extra urohyals, sesamoid ossifications, trapezoid-shaped prevomer, three basibranchials, five hypural, lack of bony bridge between the parietal and pterotic, having over 20 procurrent rays supporting the adipose crest. The detailed skeletal description of P. cristata showed that this species can be easily distinguished from the related genera. Despite the mtDNA COI result, the osteological data of this species showed some features to describe it as a distinctive genus, but this needs the osteological data of the all other Paraschistura species to be compared.

Determination of tectonic setting and situation of salt domes in Central Iran is the main purpose of this study. Central Iran is a triangle zone that is bounded by Alborz and Zagros Mountains. According to age and geological setting of evaporitic deposits revealed by field work method, diapiric provinces of Central Iran have been determined and delineated from each other. The location and general trend of the six diapiric provinces are mapped from the border zones of Central Iran by investigation of ETM+ satellite images. Also, based on the shape and orientation investigations of salt domes, tectonic processes (external trigger) are predominant compared to halokinesis (internal trigger) in Central Iran.

The isolation-by-distance theory states that the genetic differentiation between individuals raised by increasing geographic distance. Therefore, this study tested this hypothesis for Garra rufa, a freshwater fish species of Iranian inland waters, from six rivers located at the different distances in Tirgis basin. For this purpose, eight variable microsatellite loci were applied to identify geographic-based population structure of G. rufa. From 240 fish of six populations, 102 alleles were found with a mean number of 11.625 to 13.250 alleles. Heterozygosity was ranged 0.567-0.638 in six studied populations. Moreover, a significant deviations from Hardy-Weinberg were found in the studied populations. Unweight pair group analysis indicated that the six studied populations could be divided into four major clusters. The results revealed a fairly high level of genetic variation in the microsatellite loci within six studied populations. Wright's fixation index ranged between 0.013-0.044 indicating little genetic differentiation between populations. Within this range, however, we found a strong positive relation between Fst and geographical distance lending support to the isolation-by-distance theory.