Application of vertical electrical sounding for Groundwater Exploration of Al-Sarrar area, east of Sana'a Governorate, Yemen.

Vertical Electrical Sounding (VES) method is one of many methods in geophysics that was conducted in this research at Al-Sarrar, Al-Sharfa region, Bani Hashaysh District, Sana'a Governorate, Yemen. The aim of this research is to investigate and locate the depth of groundwater layer (aquifer). Data acquisition of VES was carried out using SYSCAL R2 and WDJD-4 Resistivity & IP Instrument with Schlumburger configuration of electrode. There are nine VES point in this research with various length of cable ranging from 500 m up to 1000 m. From nine VES point shown two different of resistivity value range. Very low resistivity value with range 10 Ω.m to 169 Ω.m represents alluvium sediment (Quaternary Deposit), meanwhile, another resistivity value ranging from 3 Ω.m to 4899 represents basalt (Tertiary Volcanic). Through the vertical electrical resistivity data and boreholes available around the study area, we found that groundwater reservoirs are located in volcanic rocks, but they are filled with many geological structures, such as faults, which led to the occurrence of brock-down within them. The second type of reservoirs was inside the sandstones of the Tawila Group, which are more abundant as we head west of the study area. Therefore, volcanic rocks can be considered a harvest area as they are full of geological structures.