<p>Underground water resources face an increase stress due to human activities and global climate change. To ensure sustainable and effective management of water resources, it is important to identify and characterize hydrogeologic systems and associated processes. In Azerbaijan, the groundwater is unevenly distributed due to a wide variety of climate conditions and the lowland areas depend mainly on water supply from the mountain areas to subsist. Especially since the alluvial plain aquifers undergo over consumption and pollution due to industrial and agricultural activities.</p> <p>Our study focusses on the Talysh Mountain area in the Lesser Caucasus basin, where aquifers are characterized by alluvial terrain over volcanic-sedimentary tuff. This implies a high flow rate and quick discharge to low land. Yet, this area is also characterized by higher precipitation than evaporation which makes it favorable to host consequent groundwater aquifer. Geophysics has proved many times that it can bring valuable information to hydrogeological issue in subsurface environment such as unconsolidated ground or weathered hard rock aquifers. Thus, this project aims to characterized the underground structure (lithology, weathering profiles, fault and fissures, etc.) of a mountain aquifer in the region with Electrical Resistivity Tomography (ERT). We realized three separate measurements along the Lenkaran river which should enable us to image the 2D heterogeneity at the catchment scale and identify preferential pathways which influence the hydrodynamic circulations.</p> <p>All three tomographies display two main resistivity layers which seem to be linked to the location along the river. The first layer shows resistivities in between 100 Ω.m with 3 m thickness upstream to 600 Ω.m and 6 m thickness downstream. The second layer is less resistive as a whole and goes from 60 Ω.m upstream to 15 Ω.m downstream. The resistivity limit in-between these two layers is rather abrupt and appear more linear downstream whereas the two profiles up stream display a non-linear limit. We interpret the first layer as dry alluvial sediments over a sedimentary tuff with an irregular top limit. The difference of resistivity from upstream to downstream could be linked to small changes in the lithology as well as variations of water content.</p> <p>To help interpret further the hydrodynamic circulations in the region, these geophysical images will need to be associated with two essential data: groundwater levels and rainfall. Hydrogeology and hydrogeophysics campaign are rarely applied in Azerbaijan, especially in mountain areas, and existing data are either not available or date back to the 1960’s. This study represents the first step in developing environmental geophysics research in Azerbaijan and help put light on key environmental issues in the country.</p>

<p>Kurgans are funeral chambers, evidence of burial tradition dating back to the first thousand years BCE, of nomadic populations that covered a vast area in-between Europe and Asia. In Azerbaijan, past archaeological explorations revealed numerous large kurgans from the Early Bronze, which correspond to Kura-Arexed period (ca. 3500-3000 BCE), and relatively smaller burials of Late Bronze/Early Iron Ages. To improve the efficiency of the excavation process, geophysical methods have been widely and effectively applied for many years to provide clear and useful images of archeological targets hidden underground such as kurgans.</p> <p>In this work, we introduce a multi-method archaeo-geophysical survey done in May 2022 to investigate Early Bronze Age kurgans located in Uzun Rama Steppe of Goranboy region in Azerbaijan. Applied method cover different depth of investigation and resolution to provide a wealth of information on the structure of three kurgans aligned in a North-South direction. It comprises coincidental DC-resistivity and seismic refraction tomographies of 70.5 m with a 1.5 m spacing going over all kurgans, a Ground Penetrating Radar (GPR) 40 m long profile using a 500 MHz antenna on the northern kurgans going from East to West and a magnetic map 24 x 25 m on the southern one.</p> <p>The DC-resistivity profile shows two layers, a medium resistivity layer (500 to 600 W.m) from the surface to 6 m depth and a very conductive layer (> 10 W.m) under it. The first layer contains three areas of lower resistivity (~ 60 W.m) that are limited in thickness and length. As these three spots are marked by higher height on-site, we interpret them as the three kurgans. The coincidental seismic profile is a lot less detailed (due to physical properties and higher spacing between receiver) and define only three homogeneous layers, a first layer from the surface to 1 m depth with a P-wave velocity of 300 m/s, a second layer of higher velocity (1000 m/s) from 1 m depth to approximately 6 m depth and a final third layer of 2000 m/s velocity. Even though, the resolution is lower, we interpret the first layer as an attempt of the model to represent the kurgans. The GPR profile give a high attenuate image due to low resistive layer. However multiple diffractions can be seen in the first meter of the subsurface that can indicate the presence of ancient artefact related to the kurgans. Finally, the magnetic map defines the limit of the kurgan as a positive-negative anomaly probably due to the burning ritual that ended the implementation of a kurgan.</p> <p>This geophysical campaign allowed us to accurately locate the kurgans as well as provide information on the environment. DC-resistivity and magnetic mapping seem to get the best results in our case. A future archaeological investigation will be put in place based on these results.</p>