Improving WRF-Hydro runoff simulations of heavy floods through the sea surface temperature fields with higher spatio-temporal resolution

This study investigates the impact of the spatio-temporal accuracy of four different sea surface temperature (SST) datasets on the accuracy of the Weather Research and Forecasting (WRF)-Hydro system to simulate hydrological response during two catastrophic flood events over the Eastern Black Sea (EBS) and the Mediterranean (MED) regions of Turkey. Three time-variant and high spatial resolution external SST products (GHRSST, Medspiration and NCEP-SST) and one coarse-resolution and time-invariant SST product (ERA5- and GFS-SST for EBS and MED regions, respectively) already embedded in the initial and the boundary conditions datasets of WRF model are used in deriving near-surface atmospheric variables through WRF. After the proper event-based calibration is performed to the WRF-Hydro system using hourly and daily streamflow data in both regions, uncoupled model simulations for independent SST events are conducted to assess the impact of SST-triggered precipitation on simulated extreme runoff. Some localized and temporal differences in the occurrence of the flood events with respect to observations depending on the SST representation are noticeable. SST products represented with higher cross-correlations (GHRSST and Medspiration) revealed significant improvement in flood hydrographs for both regions. The GHRSST dataset shows a substantial improvement in NSE (~70%), RMSE reduction up to 20%, and an increase in correlation from 0.3 to 0.8 with respect to the invariable SST (ERA5) in simulated runoffs over the EBS region. The use of both GHRSST and Medspiration SST data characterized with high spatio-temporal correlation resulted in runoff simulations exactly matching the observed runoff peak of 300 m³/s by reducing the overestimation seen in invariable SST (GFS) in the MED region. Improved precipitation simulation skills of the WRF model with the detailed SST representation show that the hydrographs of GHRSST and Medspiration simulations show better performance compared to the simulated hydrographs by observed precipitation.     

Stable isotope geochemistry of Quaternary calcretes in the Mersin area, southern Turkey – A comparison and implications for their origin

In the Mersin area, Quaternary calcretes are widespread, and occurred in a variety of forms, as namely powdery, nodular, tubular, fracture-infill, laminar crust, hard laminated crust (hardpan), pisolithic crust. They are predominantly calcite, and small amount of palygorskite associated with them as a minor component. Calcite δ¹⁸O and δ¹³C values of the calcretes vary from −4.31 to −6.82 and from −6.03 to −9.65‰ PDB, respectively. These values are consistent with values of pedogenic calcretes reported in literature from worldwide sites. The oxygen isotope values indicate formation under the influence of meteoric water at estimated temperatures from 25 to 32 °C. The carbon isotope values are typical for pedogenic calcretes, reflecting development under the C3-dominated vegetation cover and semiarid or seasonally arid climatic conditions.     

Polyphase Alpine deformation at the northern edge of the Menderes–Taurus block, North Konya, Central Turkey

Low-grade metamorphic rocks of Paleozoic–Mesozoic age to the north of Konya, consist of two different groups. The Silurian–Lower Permian Sizma Group is composed of reefal complex metacarbonates at the base, and flyschoid metaclastics at the top. Metaigneous rocks of various compositions occur as dykes, sills, and lava flows within this group. The ?Upper Permian–Mesozoic age Ardicli Group unconformably overlies the Sizma Group and is composed of, from bottom to top, coarse metaclastics, a metaclastic–metacarbonate alternation, a thick sequence of metacarbonate, and alternating units of metachert, metacarbonates and metaclastics. Although pre-Alpine overthrusts can be recognized in the Sizma Group, intense Alpine deformation has overprinted and obliterated earlier structures. Both the Sizma and Ardicli Groups were deformed, and metamorphosed during the Alpine orogeny. Within the study area evidence for four phases of deformation and folding is found. The first phase of deformation resulted in the major Ertugrul Syncline, overturned tight to isoclinal and minor folding, and penetrative axial planar cleavage developed during the Alpine crustal shortening at the peak of metamorphism. Depending on rock type, syntectonic crystallization, rotation, and flattening of grains and pressure solution were the main deformation mechanisms. During the F₂-phase, continued crustal shortening produced coaxial Type-3 refolded folds, which can generally be observed in outcrop with associated crenulation cleavage (S₂). Refolding of earlier folds by the noncoaxial F₃-folding event generated Type-2 interference patterns and the major Meydan Synform which is the largest map-scale structure within the study area. Phase 3 structures also include crenulation cleavage (S₃) and conjugate kink folds. Further shortening during phase 4 deformation also resulted in crenulation cleavage and conjugate kink folds. According to thin section observations, phases 2–4 crenulation cleavages are mainly the result of microfolding with pressure solution and mineral growth.     

Strain analysis along the North Analtolian Fault by using geodetic surveys

In earthquake prediction studies geodetic surveys play a very significant role. For this purpose, in Turkey, three micro geodetic networks have been established across the North Anatolian Fault. Of these, the Ismetpa§a Network is the subject of this paper. From the observations in combined triangulation—trilateration mode in 1972 and 1982 the horizontal movements and strain components were determined. Afterwards the parameters of the best fitting deformation model were computed and analyzed. The results show that the Anatolian plate has about a 1 cm/year westward motion, and there exists considerable strain accumulation in the area.     

Analysis of distortions in the National Geodetic Network of Saudi Arabia

Summary The first order horizontal control network of Saudi Arabia, which is a purely terrestrial network established in early 1970's by EDM traversing, is analyzed for distortions. The analysis is based on comparisons of the terrestrial network positions with those obtained from a 22 point GPS network uniformly covering the country. An analysis of the discrepancies in slant ranges obtained from the two networks indicates that the terrestrial network scale is smaller than that of the GPS network by about 1.68 parts per million (ppm). The scale appears to change with position suggesting some small systematic distortion of the terrestrial network relative to the GPS network. A similar analysis of the discrepancies in horizontal distance, azimuth and zenith distance also points to some non-uniformities, albeit small ones, in the terrestrial network. The discrepancies appear to be position-dependent and hence non-random in character. The maxima of the magnitudes are 2.5 ppm, 0.4 and 2.7 respectively for the discrepancies in horizontal scale, azimuth and zenith distance.     

Investigation of soil dynamic characteristics at seismic stations using H/V spectral ratio method in Marmara Region,Turkey

Natural Hazards - The North Anatolian Fault Zone (NAFZ) between the Arabian, Eurasian and African plates is one of the world’s most dangerous tectonic units. After the 1939 Erzincan...     

Metamorphic evolution of blueschists of the Altınekin Complex,Konya area,south central Turkey

The Altınekin Complex in south central Turkey forms part of the south‐easterly extension of the Tavşanlı Zone, a Cretaceous subduction complex formed during the closure of the Neo‐Tethys ocean. The protoliths of metamorphic rocks within the Altınekin Complex include peridotites, chromitites, basalts, ferruginous cherts and flysch‐facies impure carbonate sediments. Structurally, the complex consists of a stack of thrust slices, with massive ophiolite tectonically overlying a Cretaceous sediment‐hosted ophiolitic mélange, in turn overlying a sequence of Mesozoic sediments. Rocks within the two lower structural units have undergone blueschist–facies metamorphism. Petrographic, mineral–chemical and thermobarometric studies were undertaken on selected samples of metasedimentary and metabasic rock in order to establish the time relations of deformation and metamorphism and to constrain metamorphic conditions. Microstructures record two phases of plastic deformation, one predating the metamorphic peak, and one postdating it. Estimated peak metamorphic pressures mostly fall in the range 9–11 kbar, corresponding to burial depths of 31–38 km, equivalent to the base of a continental crust of normal thickness. Best‐fit peak metamorphic temperatures range from 375 to 450°C. Metamorphic fluids had high H₂O:CO₂ ratios. Peak metamorphic temperature/depth ratios (T/d values) were low (c. 10–14°C/km), consistent with metamorphism in a subduction zone. Lawsonite‐bearing rocks in the southern part of the ophiolitic mélange record lower peak temperatures and T/d values than epidote blueschists elsewhere in the unit, hinting that the latter may consist of two or more thrust slices with different metamorphic histories. Differences in peak metamorphic conditions also exist between the ophiolitic mélange and the underlying metasediments. Rocks of the Altınekin Complex were subducted to much shallower depths, and experienced higher geothermal gradients, than those of the NW Tavşanlı Zone, possibly indicating dramatic lateral variation in subduction style. Retrograde P–T paths in the Altınekin Complex were strongly decompressive, resulting in localized overprinting of epidote blueschists by greenschist–facies assemblages, and of lawsonite blueschists by pumpellyite–facies assemblages. The observation that the second deformation was associated with decompression is consistent with, but not proof of, exhumation by a process that involved deformation of the hanging‐wall wedge, such as gravitational spreading, corner flow or buoyancy‐driven shallowing of the subduction zone. Copyright © 2005 John Wiley & Sons, Ltd.     

Applicability of upflow anaerobic sludge blanket (UASB) reactor for typical sewage of a small community: its biomass reactivation after shutdown

In this study, the characteristics of sewage of small community were determined for 6 months to ascertain the type of treatment required in subtropical conditions. The results demarcated sewage of this community as a medium-strength wastewater (chemical oxygen demand: 475 mg/L, biochemical oxygen demand: 240 mg/L and total suspended solids: 434 mg/L). Chemical oxygen demand to sulphate ratio of the sewage (11.6) established that it was amenable to anaerobic digestion. The temperature, strength, biodegradability and components of sewage were suitable for anaerobic digestion, and thus, upflow anaerobic sludge blanket reactor (UASB) was selected for its treatment. These reactors are often shutdown in small communities due to environmental and/or socio-economic factors. The ability of two UASB reactors, seeded with cow dung (UASB_CD) and activated sludge of a dairy treatment plant (UASB_ASDIT) to restart after a long idle period of 12 months, was investigated along with sludge analysis by scanning electron microscope. Biomass in both reactors reactivated rapidly after shutdown period and within 30 days after substrate feeding achieved uniform removal efficiencies for chemical oxygen demand, total suspended solids, total dissolved solids, chloride and oil and grease. Chemical oxygen demand removal efficiency of both reactors became uniform and remained close to 80% after 30 days through reactivation of microbes in sludge bed due to adequate food and temperature conditions. During restart-up, at an average organic loading rate of 0.902 kg COD/m³ per day, methane yields of 0.091 and 0.084 m³/kg COD removed were achieved for UASB_CD and UASB_ASDIT reactors, respectively.