Evaluation of the temporal variations of groundwater storage and its interactions with climatic variables using GRACE data and hydrological models: A study from Turkey

Monitoring of the fluctuations of groundwater storage is particularly important in arid and semi-arid regions where water scarcity brings about various challenges. Remote sensing data and techniques play a preponderant role in developing solutions to environmental problems. The launch of Gravity Recovery and Climate Experiment (GRACE) satellites has eased the remote monitoring and evaluation of groundwater resources with an unprecedented precision over large scales. Within the scope of the current study, the latest release (RL06) of GRACE mass concentrations (Mascons) from Jet Propulsion Laboratory (JPL) dataset as well as Global Land Data Assimilation System (GLDAS) models of Noah and Catchment Land Surface Model (CLSM) were used to provide Groundwater Storage Anomalies (GWSA) over Turkey. The temporal interactions of the estimated GWSA with the climatic variables of precipitation and temperature (derived from the reanalysis datasets of CHELSA [Climatologies at High resolution for the Earth's Land Surface Areas] and FLDAS [the Famine Early Warning Systems Network Land Data Assimilation System], respectively) were investigated statistically. The results suggest that there is a descending trend (from 2003 to 2016) for Terrestrial Water Storage Anomalies (TWSA) and GWSA over Turkey with a total loss of 11 and 6 cm of water, respectively. The statistical analysis results also indicate that the monthly variations of GWSA over Turkey are highly correlated with precipitation and temperature at 2-month lag. The analysis of the climatology (long-term) values of monthly GWSA, precipitation and temperature also revealed high agreement between the variables.     

Optimal Compensation and Implementation for Adaptive Optics Systems

This paper develops a compensation algorithm based on Linear–Quadratic–Gaussian (LQG) control system design whose parameters are determined (in part) by a model of the atmosphere. The model for the atmosphere is based on the open-loop statistics of the atmosphere as observed by the wavefront sensor, and is identified from these using an auto-regressive, moving average (ARMA) model. The (LQG) control design is compared with an existing compensation algorithm for a simulation developed at ESO that represents the operation of MACAO adaptive optics system on the 8.2 m telescopes at Paranal, Chile. This revised version was published online in July 2006 with corrections to the Cover Date.     

Rate of strike-slip motion on the Amanos Fault (Karasu Valley, southern Turkey) constrained by K–Ar dating and geochemical analysis of Quaternary basalts

The left-lateral Amanos Fault follows a 200-km-long and up to 2-km-high escarpment that bounds the eastern margin of the Amanos mountain range and the western margin of the Karasu Valley in southern Turkey, just east of the northeastern corner of the Mediterranean Sea. Regional kinematic models have reached diverse conclusions as to the role of this fault in accommodating relative motion between either the African and Arabian, Turkish and African, or Turkish and Arabian plates. Local studies have tried to estimate its slip rate by K–Ar dating Quaternary basalts that erupted within the Amanos Mountains, flowed across it into the Karasu Valley, and have since become offset. However, these studies have yielded a wide range of results, ranging from 0.3 to 15 mm a⁻¹, which do not allow the overall role and significance of this fault in accommodating crustal deformation to be determined. We have used the Cassignol K–Ar method to date nine Quaternary basalt samples from the vicinity of the southern part of the Amanos Fault. These basalts exhibit a diverse chemistry, which we interpret as a consequence varying degrees of partial melting of their source combined with variable crustal contamination. This dating allows us to constrain the Quaternary slip rate on the Amanos fault to 1.0 to 1.6 mm a⁻¹. The dramatic discrepancies between past estimates of this slip rate are partly due to technical difficulties in K–Ar dating of young basalts by isotope dilution. In addition, previous studies at the key locality of Hacılar have unwittingly dated different, chemically distinct, flow units of different ages that are juxtaposed. This low slip rate indicates that, at present, the Amanos Fault takes up a small proportion of the relative motion between the African and Arabian plates, which is transferred southward to the Dead Sea Fault Zone. It also provides strong evidence against the long-standing view that its slip continues offshore to the southwest along a hypothetical left-lateral fault zone located south of Cyprus.     

Accuracy analysis, dem generation and validation using russian tk-350 stereo-images

TK-350 stereo-scenes of the Zonguldak testfield in the north-west of Turkey have been analysed. The imagery had a base-to-height ratio of 0·52 and covered an area of 200 km × 300 km, with each pixel representing 10 m on the ground. Control points digitised from 1:25 000 scale topographic maps were used in the test. A bundle orientation was executed using the University of Hanover program BLUH and PCI Geomatica OrthoEngine AE software packages. Tests revealed that TK-350 stereo-images can yield 3D geopositioning to an accuracy of about 10 m in planimetry and 17 m in height. A 40 m resolution digital elevation model (DEM) was generated by the PCI system and compared against a reference DEM, which was derived from digitised contour lines provided by 1:25 000 scale topographic maps. This comparison showed that accuracy depends mainly on the surface structure and the slope of the local terrain. Root mean square errors in height were found to be about 27 and 39 m outside and inside forested areas, respectively. The matched DEM demonstrated a systematic shift against the reference DEM visible as an asymmetric shift in the frequency distribution. This is perhaps caused by the presence of vegetation and buildings.     

Teleseismic finite-fault inversion of two <Emphasis Type="Italic">M</Emphasis><Subscript>w</Subscript> = 6.4 earthquakes along the East Anatolian Fault Zone in Turkey: the 1998 Adana and 2003 Bingöl earthquakes

The East Anatolian Fault Zone is a continental transform fault accommodating westward motion of the Anatolian fault. This study aims to investigate the source properties of two moderately large and damaging earthquakes which occurred along the transform fault in the last two decades using the teleseismic broadband P and SH body waveforms. The first earthquake, the 27 June 1998 Adana earthquake, occurred beneath the Adana basin, located close to the eastern extreme of Turkey’s Mediterranean coast. The faulting associated with the 1998 Adana earthquake is unilateral to the NE and confined to depths below 15 km with a length of 30 km along the strike (53°) and a dipping of 81° SE. The fixed-rake models fit the data less well than the variable-rake model. The main slip area centered at depth of about 27 km and to the NE of the hypocenter, covering a circular area of 10 km in diameter with a peak slip of about 60 cm. The slip model yields a seismic moment of 3.5?×?10¹⁸ N-m (M_w???6.4). The second earthquake, the 1 May 2003 Bingöl earthquake, occurred along a dextral conjugate fault of the East Anatolian Fault Zone. The preferred slip model with a seismic moment of 4.1?×?10¹⁸ N-m (M_w???6.4) suggests that the rupture was unilateral toward SE and was controlled by a failure of large asperity roughly circular in shape and centered at a depth of 5 km with peak displacement of about 55 cm. Our results suggest that the 1998 Adana earthquake did not occur on the mapped Göksun Yakap?nar Fault Zone but rather on a SE dipping unmapped fault that may be a split fault of it and buried under the thick (about 6 km) deposits of the Adana basin. For the 2003 Bingöl earthquake, the final slip model requires a rupture plane having 15° different strike than the most possible mapped fault.     

Soil gas radon concentrations along the Ganos Fault (GF)

In this study, soil radon levels have been measured for the first time across the Ganos fault (GF), which is known as the western part of the North Anatolian Fault Zone. LR 115 Type 2 Solid State Nuclear Track Detectors (time integrated) have been applied to determine soil gas radon levels, and the survey was performed in 16 stations along the fault line. The results showed that soil gas radon concentrations and variation of concentration levels are comparable high along the fault line. It is also observed that in the middle of the Ganos Fault, fairly elevated radon levels were detected. These can be related to the activity of the fault lines. It is confirmed that the study area has a very active tectonic structure and is great location for analyzing radon variations.