Groundwater Vulnerability Map of Lusaka Province / Zambia
Background:
In 2012, the Groundwater Resources Management Support Programme (GReSP), a cooperation project between the Department of Water Affairs (DWA), Zambia, and the Federal Institute for Geosciences and Natural Resources (BGR), Germany, issued the groundwater vulnerability map for Lusaka Province, Zambia. The map was distributed along with hydrogeological maps of Lusaka and its surroundings including the Mwembeshi and Chongwe areas, a manual for map interpretation and a brief description of the groundwater resources of the area.
Groundwater Vulnerability Map of Lusaka Province
Within the framework of a short-term project entitled "Groundwater advisory for the long-term prevention of cholera epidemics in Lusaka, Zambia" from June 2018 to April 2019, a modified version of the groundwater vulnerability map was issued in cooperation with the Water Resources Management Authority (WARMA), Zambia. In the modified map, part of the information is updated, including the production and monitoring boreholes within Lusaka. Furthermore, the map puts its focus on the possible influence that groundwater has on the spread of waterborne diseases. This is done using the example of the cholera epidemic in Lusaka during the rainy season 2017/2018. The locations where cholera cases occurred are put in relation with hydrogeological information like the depth to groundwater. It can be seen that areas with shallow water tables like Kanyama, which are very vulnerable to groundwater pollution, were among the hotspots of the cholera outbreak. The project study furthermore found that cholera hotspots might not only be caused by groundwater pollution at site but also within the recharge area of the respective groundwater abstraction point. Therefore, the flow directions are clearly indicated in the map. It has to be emphasized that groundwater in moderately vulnerable areas might also be polluted, either because of
- inflow of polluted groundwater from areas of higher vulnerability,
- high risk of contamination (e.g., dense settlements with inappropriate sanitation) or
- contamination directly at site (e.g., when a borehole is built next to a septic tank).
In sum, the likelihood of groundwater pollution does not only depend on the vulnerability and risk to contamination at site but also on the hydrogeological situation and pollution sources within the upstream area (i.e., where groundwater is coming from).
The modified map includes short explanations about the methodology to derive the vulnerability classes and about the influence depth to groundwater, sanitation type and groundwater flow direction have on groundwater pollution and, potentially, on the occurrence of waterborne diseases. Hence, the map provides a very brief summary of the findings of the project described in the final project report (Karen et al., 2019).
Since it is distributed as wall map, the originally accompanying manuals and explanations are not provided with the map. Therefore, digital copies of the manuals and of the references used for the map are provided on this website.
Map:
Methodology to derive vulnerability classes of Lusaka and surroundings:
The vulnerability classes were derived in 2011 using a modified version of the PI method by Goldschneider et al. (2000). The application of the method is described in Nick (2011).
- GOLDSCHEIDER, N., KLUTE, M., STURM, S. & HÖTZL, H. (2000): The PI Method – a GIS-based Approach to Mapping Groundwater Vulnerability with Special Consideration of Karst Aquifers. Zeitschrift für Angewandte Geologie, 46 (2000) 3: 157-166; Hannover.
- NICK, A. (2011): Methodology and Results of the Vulnerability Map for Lusaka and Surroundings using the PI-Method – A Documentation and Manual. - Technical Note No 6, prepared by Department of Water Affairs (DWA), Zambia & Federal Institute for Geosciences and Natural Resources (BGR), Germany; 36 p., 20 fig., 5 tab.; Lusaka. (PDF, 4 MB)
Explanation of the map and basic information about Lusaka Region:
A manual on how to interpret the vulnerability map is given by:
For a brief description of the groundwater resources of the wider Lusaka area refer to:
Additional information on the possible influence of groundwater on cholera occurrence in Lusaka:
Data displayed in the map and further information:
For information regarding the water supply and the sewerage and drainage of Lusaka, refer to:
- KRI INTERNATIONAL CORP, NIPPON KOEI CO Ltd & JAPAN ENGINEERING CONSULTANTS (2009): The Study on Comprehensive Urban Development Plan for the City of Lusaka in the Republic of Zambia - Final Report (March 2009), Volume II Chapter 2: Water supply and sewerage/drainage. Ministry of Local Government and Housing, Lusaka City Council and Japan International Cooperation Agency: 69 pp; Lusaka (Modified).
For the background on the land use classification refer to:
The potential future well fields of Lusaka, shown in the map, were suggested in the following report:
For information about groundwater monitoring in Lusaka refer to:
Data on cholera occurrence during the 2017/2018 epidemic in Lusaka were obtained from Zambia National Public Health Institute (ZNPHI) and Right to Care Zambia.
Information on sewer lines and production boreholes displayed in the map was received from Lusaka Water and Sewerage Company (LWSC).
The data on Wards were obtained from the Zambian Central Statistical Office.
Contact 1:
Contact 2:
