Geophysical Characterization of Waterlogging Phenomenon at Merowe – Sudan

Abstract

Merowe town and the surrounding irrigated agricultural scheme have been affected by a severe waterlogging phenomenon, which has led to the collapse of numerous residential structures. This study aims to investigate the causes of groundwater table rise to near-surface levels and to propose appropriate mitigation measures. A geoelectrical investigation using the Vertical Electrical Sounding (VES) method was conducted and integrated with hydrogeological assessments and an evaluation of irrigation practices in the study area. The geology of the area is dominated by the Nubian Sandstone Formation, which is overlain by Quaternary to Recent sediments including Nile silt, alluvial deposits, and aeolian (wind-blown) sediments. Geophysical investigations indicate that the principal aquifer system comprises alluvial deposits consisting predominantly of sand, silt, and gravel, with a thickness generally of less than 10 m and resistivity values ranging from 300 to 1000 Ω•m. Underlain by pebbly sandstone and coarse- to medium-grained sandstone units, with thicknesses ranging from 20 to 50 m and resistivity values between 80 and 300 Ω•m. These sandstone units are intermittently interbedded with mudstone layers exhibiting resistivity values of less than 20 Ω•m. The Sum of Excess Water index revealed that the northern part of the study is very poorly drained. Surface water accumulation resulting from excessive irrigation is enhanced by the prevailing geological structure, which restricts effective subsurface drainage and consequently leads to a rise in the groundwater table. To mitigate these conditions, the study recommends improving irrigation management within the agricultural scheme. Integrated irrigation management, combining controlled surface canal irrigation with groundwater abstraction, is suggested as an effective strategy.