Use of subsurface temperature as a groundwater flow tracer in the environs of Ismailia Canal, Eastern Nile Delta, Egypt

Abstract

Measurements of the groundwater–temperature with depths in a borehole can be utilized to determine the direction and velocity of the groundwater flow. Temperature–depth profiles were measured in 11 observation wells adjacent to Ismailia Canal, Eastern Nile Delta region, Egypt. The steady-state heat conduction and advection equation in vertical one dimension were used to estimate vertical velocity and direction of the groundwater flow. Presenting of the obtained temperature–depth profiles in vertical two dimensions showed that the distribution of the subsurface temperature varied according to the direction of the groundwater movement. The subsurface warm zones indicate the gaining effect of Ismailia Canal and the surface warming. Obtained results suggested the existence of upward groundwater flow in most of the examined boreholes with velocities ranging from 13 to 162 cm/year, while only two boreholes showed a downward groundwater flow with a mean velocity of about 52 cm/year. The estimated upward movement of groundwater in the eastern part of the study area around Ismailia Canal makes the groundwater a potential cause for waterlogging occurrences in that part. Deviation of subsurface temperature profiles that is caused by advection, from the distribution profiles, which are affected only by conduction, can be analyzed to estimate the vertical water fluxes.