Longitudinally and laterally trench supporting subsurface dam innovative design procedures

According to the Paris climate change agreement, temperature increases of around 1.5 or 2.0 degrees C by 2050 are bound to increase the amounts of evaporation and evapotranspiration, which are among the losses from surface water bodies, such as rivers, lakes, reservoirs and dams. In order to reduce these losses and support local water supply, subsurface dam construction projects are at the forefront in many countries, especially in arid and semi-arid regions, even in subtropical climate regions. In the literature, there are classical methodological explanations for underground dams with quite insufficient and restrictive interpretations. In this paper, two very similar but different new alternatives are proposed as longitudinally and laterally supportive underground dams with inspirations from historical qanat groundwater subsurface structures. Both types are supported by artificial trenches with higher hydraulic conductivity than the surrounding Quaternary alluvial deposits to increase external and meanwhile to support internal areal recharge possibilities between the trenches and the surrounding natural porous, weathered and fractured layers. It is noticed that trench-supportive subsurface dams are more effective, affordable, sustainable and manageable than classical alternatives available in the literature. It is recommended that a more refined subsurface groundwater movement mathematical formulation should be developed in the future.