Impact of climate change on the hydrology and water salinity in the Anzali Wetland,northern Iran

ABSTRACT

The impact of climate change on hydrology and water salinity of a valuable coastal wetland (Anzali) in northern Iran is assessed using daily precipitation and temperature data from 19 models of Coupled Model Inter-comparison Project Phase 5. The daily data are transiently downscaled using the Long Ashton Research Station Weather Generator to three climatic stations. The temperature is projected to increase by +1.6, +1.9 and +2.7°C and precipitation to decrease by 10.4%, 12.8% and 12.2% under representative concentration pathway (RCP) scenarios RCP2.6, RCP4.5 and RCP8.5, respectively. The wetland hydrology and water salinity are assessed using the water balance approach and mixing equation, respectively. The upstream river flow modelled by the Soil and Water Assessment Tool is projected to reduce by up to 18%, leading to reductions in wetland volume (154 × 10⁶ m³), area (57.47 km²) and depth (2.77 m) by 34%, 21.1% and 20.2%, respectively, under climate change, while the mean annual total dissolved solids (1675 mg/L) would increase by 49%. The reduced volume and raised salinity may affect the wetland ecology.     

Geochemical and geochronological evidence for a Middle Permian oceanic plateau fragment in the Paleo-Tethyan suture zone of NE Iran

The mafic–ultramafic Fariman complex in northeastern Iran has been interpreted as a Paleo-Tethyan ophiolitic fragment with subduction- and plume-related characteristics as well as a basin deposit on an active continental margin. Contributing to this issue, we present geochemical, geochronological, and mineralogical data for transitional and tholeiitic basalts. Thermodynamic modeling suggests picritic parental magmas with 16–21 wt% MgO formed at plume-like mantle potential temperatures of ca. 1460–1600 °C. Rare pyroxene spinifex textures and skeletal to feather-like clinopyroxene attest to crystallization from undercooled magma and high cooling rates. Chromium numbers and TiO₂ concentrations in spinel are similar to those in intraplate basalts. ⁴⁰Ar–³⁹Ar dating of magmatic hornblende yielded a plateau age of 276?±?4 Ma (2σ). Transitional basalt with OIB-like trace element characteristics is the predominant rock-type; less frequent are tholeiitic basalts with mildly LREE depleted patterns and picrites with intermediate trace element characteristics. All samples show MORB-OIB like Pb/Ce, Th/La, and Th/Nb ratios which preclude subduction-modified mantle sources and felsic crustal material. Tholeiitic basalts and related olivine cumulate rocks show MORB-like initial ε_Nd values of +?9.4 to +?6.2 which define a mixing line with the data for the transitional basalts (ε_Nd ca. +?2.6). Initial ¹⁸⁷Os/¹⁸⁸Os ratios of 0.124–0.293 support mixed sources with a high proportion of recycled mafic crust in the transitional basalts. High concentrations of highly siderophile elements are in agreement with the high mantle potential temperatures and inferred high-melting degrees. It is argued that the Fariman complex originated by melting of a mantle plume component as represented by the OIB-like transitional basalt and entrained asthenosphere predominant in the MORB-like tholeiites. Two lines of evidence such as association of the Fariman complex with pelagic to neritic sedimentary rocks and the tectonic position at the boundary of two continental blocks defined by ophiolites and accretionary complexes of different ages suggest formation in an oceanic domain. Thus, we interpret it as a fragment of an oceanic plateau, which escaped subduction and was accreted as exotic block in the Paleo-Tethyan suture zone.     

Assessment of agricultural groundwater users in Iran: a cultural environmental bias

Many environmental problems are rooted in human behavior. This study aimed to explore the causal effect of cultural environmental bias on ‘sustainable behavior’ among agricultural groundwater users in Fars province, Iran, according to Klockner’s comprehensive model. A survey-based research project was conducted to gathering data on the paradigm of environmental psychology. The sample included agricultural groundwater users (n = 296) who were selected at random within a structured sampling regime involving study areas that represent three (higher, medium and lower) bounds of the agricultural-groundwater-vulnerability spectrum. Results showed that the “environment as ductile (EnAD)” variable was a strong determinant of sustainable behavior as it related to groundwater use, and that EnAE had the highest causal effect on the behavior of agricultural groundwater users. The adjusted model explained 41% variance of “groundwater sustainable behavior”. Based on the results, the groundwater sustainable behaviors of agricultural groundwater users were found to be affected by personal and subjective norm variables and that they are influenced by casual effects of the “environment as ductile (EnAD)” variable. The conclusions reflect the Fars agricultural groundwater users’ attitude or worldview on groundwater as an unrecoverable resource; thus, it is necessary that scientific disciplines like hydrogeology and psycho-sociology be considered together in a comprehensive approach for every groundwater study.     

Flash flood hazard mapping based on quantitative hydrology,geomorphology and GIS techniques (case study of Wadi Al Lith,Saudi Arabia)

Flash floods are considered as catastrophic phenomena possessing major hazardous threat to the coastal cities, towns, villages and infrastructures. This study deals with the evaluation of flash flood hazard in the ungauged Wadi Al Lith basin depending on detailed morphometric characteristics of Al Lith basin and its sub-basins. For the detailed study, ASTER data were used for preparing digital elevation model (DEM), and geographical information system (GIS) was used in the evaluation of linear, areal and relief aspects of morphometric parameters. The major parameters such as watershed boundary, flow accumulation, flow direction, flow length and stream ordering are prepared using the ArcHydro Tool. Surface Tool in ArcGIS-10 software, and ASTER (DEM) was used to create different thematic maps such as DEM, contour, slope aspect and hill shade maps. Twenty-five morphometric parameters were measured, calculated and interlinked to produce nine effective parameters for evaluation of the flash flood hazard degree of the study area. Based on nine morphometric parameters which affect the hydrologic behaviour of the Wadi, by influence on time of concentration which has a direct influence on flooding prone area. The flash flood hazard of the Al Lith basin and its sub-basins was identified and classified into three groups (high, medium and low hazard degree). The study provides details on the flash flood-prone area (Wadi Al Lith) and the mitigation measures. This study also helps to plan rainwater harvesting and watershed management in the flash flood alert zones.     

Correction to: New climatic zones in Iran: a comparative study of different empirical methods and clustering technique

Theoretical and Applied Climatology -     

Development of a new wavelet-based hybrid model to forecast multi-scalar SPEI drought index (case study: Zanjan city,Iran)

Theoretical and Applied Climatology - Drought forecasting plays a vital role in managing drought and reducing its effects on agricultural systems and water resources. In the present study, three...     

Estimation of groundwater recharge in arid, data scarce regions; an approach as applied in the El Hawashyia basin and Ghazala sub-basin (Gulf of Suez, Egypt)

In this study, an approach for runoff and recharge estimations that can be applied in arid regions which suffer from lack of data is presented. Estimating groundwater recharge in arid regions is an extremely important but difficult task, the main reason is the scarcity of data in arid regions. This is true for the Eastern Egyptian Desert where groundwater is used for irrigation purposes in agricultural reclamation along the Red Sea coast line. As a result of the scarcity of hydrologic information, the relation between rainfall and runoff was calculated depending on the paleo-flood hydrology information. Two models were used to calculate the rainfall–runoff relationships for El Hawashyia basin and Ghazala sub-basin. Two computer programs known as Gerinne (meaning channel in German) and SMADA6 (Stormwater Management and Design Aid, version 6) were conjunctively used for this purpose. As a result of the model applied to El Hawashyia basin, a rainfall event of a total of 18.3 mm with duration 3 h at the station of Hurghada, which has an exceedance probability of 5–10 %, produces a discharge volume of 10.2 × 10⁶ m³ at the delta, outlet of the basin, as 4.7 mm of the rainfall infiltrates (recharge). For the Ghazala sub-basin, the model yields a runoff volume of 3.16 × 10⁶ m³ transferred from a total rainfall of 25 mm over a period of 3 h, as 3.2 mm of it was lost as infiltration.     

Ranking the rock slope instability potential using the Interaction Matrix (IM) technique; a case study in Iran

All the conventional techniques for the analysis of slope stability ranging from simple kinematic analysis using stereonets, to the various widely used limit equilibrium methods, to sophisticated numerical methods belong to a category that are generally known as the analytic approaches and thus are only able to consider a limited number of affecting factors and then solve the problem in details. In contrast, the systems approaches not only can examine the problem in its totality with a complete list of the components, but also can take the interactions between the factors into account. This paper presents a complete application of a well-known systems technique named the Interaction Matrix (IM) in ranking the instability potential of rock slopes of the Khosh-Yeylagh Main Road, Iran as the case study of the research. For this purpose, 15 stations have been selected and a relatively comprehensive database containing the fieldwork information has been constructed. Following the IM technique, the most important factors relating to the general environment and to the rock mass characteristics have been considered. Their reciprocal causes and effects have been analyzed in order to weight each parameter according to its degree of interactivity in the system. Then, the slope instability index has been calculated which refers to the inherent potential instability of each slope of the examined region. The final instability ranking has been presented for the investigated slopes in Khosh-Yeylagh Main Road based on a simple classification. The main aim of the study is to extend the use of systems approach and specifically the IM technique in slope stability analysis. Also, this research shows the importance of consideration of an approximately complete set of key parameters affecting the stability of rock slopes.     

Geodetic constraints on the period of episodic tremors and slips using least squares harmonic estimation method with application to Cascadia subduction zone

It is expected that episodic tremors and slips (ETS) as a type of slow earthquakes with periodic property will be detected using harmonic estimation techniques. The principal goal of this paper is the detection of these kinds of earthquakes using least squares harmonic estimation (LSHE). To accomplish this, the raw time series of 38 permanent GPS stations of the Pacific Northwest Geodetic Array have been analyzed. Previously, some independent techniques could confirm the occurrences of the aforementioned quakes at these stations. However, the current research intends to evaluate the spectrum of each of the de-trended time series using the LS-HE method. In each station, the period of the detected harmonic with the maximum power spectrum is equivalent to the average period previously reported for these events. According to the obtained results, the recurrence interval of these events ranges from 9 months to 3 years. In sum, the study confirms this method being efficient for investigating the occurrences of ETSs when the length of the GPS time series is sufficiently large.