BGR Bundesanstalt für Geowissenschaften und Rohstoffe

TC Namibia: The Hydrogeological Mapping Project HYMNAM

Report of the project:

Background:
Namibia is 2.5 times larger than Germany (about 825,000 km²) and has a population of less than two million. It is part of the driest region of southern Africa. There is often a lack of water because rainfall is very unevenly distributed, both areally and seasonally. Despite occasional, local heavy rains, the mean annual precipitation rate is less than 300 mm – not enough for field crops. Seeking a secure water supply, the Namibian government requested support from the German government in a survey of the country's groundwater reserves. The German Ministry for Economic Cooperation and Development (BMZ) commissioned the Federal Institute for Geosciences and Natural Resources (BGR) to carry out this Technical Cooperation project.

Drilling a well in the Kalahari trough near Coblenz in the Omatako ValleyDrilling a well in the Kalahari trough Source: BGR

Project Objective:
The objective of the project was to develop a basis for evaluating and planning the management of the countries groundwater resources. For this purpose a digital hydrogeological map of Namibia and accompanying Explanatory Notes was to be prepared. The main participants in Namibia were the Department of Water Affairs (DWA) of the Ministry of Agriculture, Water and Rural Development, the Geological Survey of Namibia (GSN) (GSN) of the Ministry of Mines and Energy, and the semi-private water utilities company Namibia Water Corporation (NamWater). Numerous other institutions and nearly all of the major consulting bureaus in Namibia made valuable contributions to the project.

Present Water Supply Situation:
An extensive canal and pipeline system was built since independence to provide a secure water supply. The water supply in the northern part of the country, north of Etosha National Park, is derived from canals carrying water from the Calueque reservoir on the Kunene River in Angola. A pipeline system in the Swakopmund/Walvis Bay region on the coast carries groundwater from the Kuiseb region and groundwater recharged from the Omaruru Delta reservoir (when it contains water). The water supply of Windhoek, the capital, comes from groundwater sources (to a decreasing percentage), processed waste water, and from a system of reservoirs and pumping stations connected by canals and pipelines. During the dry season and droughts, about ten million m³ of water are pumped from the Otavi-Tsumeb-Grootfontein karst region in the north to Windhoek in the central part of the country.

Drilling a well in the Etosha National ParkDrilling a well in the Etosha National Park Source: Metzger Drilling

Outside the population centers, the water supply is taken mainly from groundwater. Many thousands of wells have been drilled for small villages or individual farms. Of interest is a comparison of the present springs with those known at the beginning of the 20st century (1904): Of the more than 2500 springs known at that time, only about 500 are known today, many of which are only intermittent springs.

Project Results:
The Namibian-German HYMNAM cooperation project was concluded at the end of 2001 after 26 months with the publication of the book "Groundwater in Namibia" together with the 1 : 1 000 000 hydrogeological map of Namibia (HYMNAM).

Existing data was collected together with new survey data, processed, and shown on the map so that it could be used for national water management. The topographic, geological, and groundwater (well yields and water quality) data was entered in a geoinformation system together with information about water utilization and management measures. The digital geological map of the Geological Survey and the drilling database (more than 45,000 wells) of the DWA form the core of the ArcInfo information system.

The Hydrogeological Map of NamibiaThe Hydrogeological Map of Namibia Source: BGR

The quality of the data was tested during the project. Some of the data was useable only with reservation and considerable work was necessary to improve or replace it. This was particularly the case for the stream systems, the boundaries of the country, and the coordinates of towns and villages. Errors by as much as 20 km were discovered and corrected using rectified satellite images. Thus, data base for the 1 : 1 000 000 hydrogeological map was more reliable than previously possible.

The rock formations, aquifer type, and groundwater potential are presented on the map together with the updated topographic data. In addition, the map contains a considerable amount of useful detailed information about the groundwater, e.g., springs, wells, salinification, groundwater flow directions, depth to the groundwater table, engineering measures (e.g., dams, pipelines, canals, irrigated areas), and other features affecting the groundwater, e.g., mines and water protection areas. Further important themes are treated in five small-scale maps: the location of Namibia in southern Africa together with the stream systems, water divides, precipitation rates; elevations; concentrations of wells; groundwater quality; and vulnerability of aquifers to contamination. Three cross-sections through groundwater occurrences were also prepared.

The attempt was made in the Explanatory Notes to provide the nonhydrogeologist with an overview of groundwater in Namibia. This appears to have been successful, more than 1000 copies have been sold by the Scientific Society of Namibia and the Geological Survey. Thus it is hoped that the hidden resource groundwater will find recognition and consideration it is due in arid Namibia.

Source of Supply:

  • any bookstore in Namibia (ISBN No. 0-86976-571-X)
  • Namibia Wissenschaftliche Gesellschaft
    P.O.Box 67
    110 Robert Mugabe Ave
    Tel +61-225372
    E-Mail: nwg@iafrica.com.na

Literature:

CHRISTELIS, G. & STRUCKMEIER, W. (2011): Groundwater in Namibia - an Explanation to the Hydrogeological Map. - Unrevised 2nd edition of Technical Cooperation Project "HYMNAM", prepared by DWA, GSN, NAMWATER & BGR: 128 p., Windhoek. (PDF, 8 MB)

Contact:

    
Dr. Georg Houben
Phone: +49-(0)511-643-2373

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