Hydrogeological and Geological Conditions

Due to the diversity of natural environments and geological structure of Azerbaijan, the hydrogeological conditions are extraordinarily complex. Azerbaijan is situated within the Alpine fold belt and includes mountain regions of the Greater and the Lesser Caucasus (the mountainous Talish region is considered part of the Less Caucasus region), the Kura intermountain depression and part of the Caspian Sea (Fig. 13.1). The FGWR are limited within the territory of Azerbaijan and distributed irregularly [1].

Geological Map Azerbaijan
Fig. 13.1 Geomorphological map of Azerbaijan

The mountainous regions of Azerbaijan are formed of Mesozoic-Cenozoic rocks and characterized by significant relief, thick weathering zones, fracturing, abundance of mantles of deluvial/eluvial loam, and river valleys and small troughs of alluvial and fluvioglacial sediments. Groundwater is mainly associated with the weathering zone and tectonic dislocations. Shallow circulating groundwater, discharging as springs is observed in valleys and ravines of the foothills. Thickness of this zone is associated with drainage erosion depth, which is about 1,500-1,800 m. The main FGWR in these regions originates from atmospheric precipitation and melt water of the zones of glacier and ice.

The foothill and intermountain plains of the country are the regions of the richest fresh water. The foothill plains here are composed of fluvial drift cone deposits characterized by development of stratum - pore groundwater within Upper Pliocene-Quaternary and Quaternary alluvial and deluvial/eluvial sediments.

Analysis of numerous hydrogeological profiles, both longitudinal and perpendicular to ground runoff, showed the presence, in nearly all drift cones, of lithologi-cal cavities composed of boulder-gravel-pebble deposits favourable for ground runoff accumulation. The coarsest material occurs toward the top-centre of the drift cones (boulder, gravel, pebbles) while in the periphery, predominantly fine-grained loam-clay deposits occur (Fig. 13.2). In the cross section, loam-clay deposits are observed in the central part of the drift cones representing about 10% of the vertical section, but this increases to 70-90% along the periphery. This longitudinal structure is called "ridged" and plays a significant role in the formation of unconfined and confined conditions in the aquifers Cross sections and vertical sections are characterized by chaotic distributions of continental material originating from the mountain areas. These distributions are part responsible for the meandering pattern

River Deposits Fookes Ground Model
Fig. 13.2 The conceptual model of formation and expenditure of stratum - pore groundwater formation of foothill plains

of rivers. The chaotic nature of the sedimentation can lead to isolated aquifer units separated by poorly permeable beds, and can also provide "lithological windows" that allow good hydraulic interaction between otherwise discrete aquifers. So, recharge of intensive precipitation and surface drainage takes place in the upper part of the alluvial cones.

Groundwater flow beginning at the top of drift cones occurs within a single aquifer. Down flow, this aquifer becomes divided in plan and section into a series of aquifers separated by loamy-clayey deposits. These aquifers are closely associated with each other hydraulically and share a common piezometric level. They are regarded as an integrated aquifer system. The thickness of the aquifers varies from several meters to 100 m or more.

The results of research [1, 2] demonstrate that about 85-95% of the nature groundwater resources recharge, as in the aquifers of the mountain regions (fractured bedrock aquifers) as such as in the foothill and intermountain plains aquifers (strata and fluvial aquifers), are infiltration from atmospheric precipitation, condensation waters and surface water. Obtained data confirm that the FGWR formation in Azerbaijan very depends on the climatic factors. The changes of the hydrological cycle will deteriorate the availability of potable water resources for inhabitants, in terms of quantity, quality and accessibility of water supplies.

Was this article helpful?

0 0

Post a comment