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A hydrogeological study of the Nhandugue River, Mozambique – A major groundwater recharge zone

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Author

  • Kristina Arvidsson
  • Li Stenberg
  • Farisse Chirindja
  • Richard Owen
  • Torleif Dahlin

Summary, in English

The Nhandugue River flows over the western margin of the Urema Rift, the southernmost extension of the East African Rift System, and marks the north-western border of Gorongosa National Park, Mozambique. It constitutes one of the major indispensable water resources for the ecosystem that the park protects. Our study focused on the hydrogeological conditions at the western rift margin by resistivity measurements, soil sampling and discharge measurements. The resistivity results suggest that the area is heavily faulted and constitutes a major groundwater recharge zone. East of the rift margin the resistivity indicate that solid gneiss is fractured and weathered, and is overlain by sandstone and alluvial sediments. The top 10-15 m of the alluvial sequence is interpreted as sand. The sand layer extends back to the rift margin thus also covering the gneiss. The sandstone outcrops a few kilometers from the rift margin and dips towards east/south-east. Further into the rift valley, the sand is underlain by lenses of silt and clay on top of sand mixed with finer matter. In the lower end of the investigated area the lenses of silt and clay appears as a more or less continuous layer between the two sand units. The topmost alluvial sand constitutes an unconfined aquifer under which the solid gneiss forms a hydraulic boundary and the fractured gneiss an unconfined aquifer. The sandstone is an unconfined aquifer in the west, becoming semi-confined down dip. The lenses of silt and clay forms an aquitard and the underlying sand mixed with finer matter a semi-confined aquifer. The surface runoff decreases downstream and it is therefore concluded that surface water infiltrates as recharge to the aquifers and moves as groundwater in an east/south-eastward direction.

Publishing year

2011

Language

English

Pages

789-797

Publication/Series

Physics and Chemistry of the Earth

Volume

36

Issue

14-15

Document type

Journal article

Publisher

Elsevier

Topic

  • Oceanography, Hydrology, Water Resources
  • Geophysics
  • Earth and Related Environmental Sciences

Keywords

  • Gorongosa National Park
  • Groundwater recharge zone
  • Hydrogeology
  • Resistivity
  • Urema Rift

Status

Published

Project

  • Groundwater Resources Mapping in Mozambique

ISBN/ISSN/Other

  • ISSN: 1474-7065