SASSCAL - Southern African Science Service Centre for Climate Change and Adaptive Land Management

Country / Region: Africa / Southern Africa

Begin of project: January 1, 2013

End of project: October 31, 2017

Status of project: October 31, 2017

Latest activities:

• Summary of investigated landforms and estimated groundwater recharge rates in northern central Nambinia within the framework of SASSCAL – Jun 2017 (PDF, 994 KB)
• Documentation of the field activities on BGR Youtube Channel - May 2017 (PDF, 742 KB)
• Major Milestone reached - Defense of Doctoral Thesis - Nov 2016 (PDF, 95 KB)
• Major Milestone reached - Defense of Doctoral Thesis - Jul 2016 (PDF, 160 KB)
• TV Team from French-German channel ARTE visits SASSCAL - Jun 2016 (PDF, 1 MB)
• Teaching cooperation BGR-UNAM under the SASSCAL umbrella - Apr 2016 (PDF, 340 KB)
• Surface water sampling campaign of Caleque-Oshakati Canal completed - Jun 2015 (PDF, 271 KB)
• Monitoring Station established at Eenhana Forest Site - Jun 2015 (PDF, 412 KB)
• Courses for MSc Program established and held - Apr 2015 (PDF, 521 KB)
• Soil gas sampler in credit card format - Jun 2014 (PDF, 435 KB)
• First recharge rates determined for rainy season 2013/14 - Jun 2014 (PDF, 536 KB)

An international joint research initiative encompassing scientists from Angola, Botswana, Namibia, South Africa, Zambia, and Germany was launched in 2010 with the goal of establishing a Southern African Science Service Centre for Climate Change and Adaptive Land Management (SASSCAL). The initiative, funded by the German Federal Ministry of Education and Research (BMBF) was created in order to respond to the challenges of global change as well as to create scientific results and socio-economic benefits for the whole southern African region on the long run. Therefore, problem-oriented research in the area of adaptation to climate and climatic change as well as sustainable land management is conducted through interdisciplinary research in the fields of water sciences, climate, agriculture, biodiversity, forestry and capacity development.

Research camp at BGR core site ‘Eenhana Forest’ Source: BGR

Objectives:
The Federal Institute for Geosciences and Natural Resources (BGR) is involved in SASSCAL task 10 “Improving the understanding of groundwater related processes and establishing groundwater budgets for water management purposes” and task 82 “Support of the Establishment of an MSc Program of Applied and Environmental Geology at University of Namibia, Windhoek”. Together with partners from the University in Namibia (UNAM), extended field research is conducted in order to improve the knowledge about physical processes controlling groundwater recharge processes. Those can be separated into direct and indirect (recharge through surface depressions, oshanas, ephemeral river beds) pathways. Direct recharge relies on physical characteristics of the unsaturated zone (texture, vegetation etc.) and precipitation patterns (extreme events, longer wet spells etc.)

The scientific approaches therefore will focus on the unsaturated zone, where a complex interplay of land cover, soil type and spatiotemporal precipitation pattern creates highly heterogeneous preconditions for groundwater recharge. Key questions are:

Map of Cuvelai-Etosha Basin and sites Source: BGR

• How can data quality improvement help to improve groundwater assessment for water management purposes?
• Which methods will serve best for local groundwater recharge estimation in arid environments? Is it possible to regionalize these methods?
• Is it possible to sustain shallow groundwater resources as drinking water supply in consideration of climate and land use changes?
• Is it possible to enhance groundwater availability by artificial recharge in these regions?

Soil sampling using a hand auger Source: BGR

To answer these questions, a combination of various field, laboratory and theoretical methods including the interpretation of stable isotopes (deuterium and oxygen-18), numerical modeling approaches and remote sensing data is applied. Extensive field research comprising climate and groundwater monitoring as well as hydraulic testing will be conducted in order to broaden the knowledge base about spatial and temporal changes in soil water content and hence groundwater infiltration process.

Funnel shaped hand dug well in the Eastern Sand Zone Source: BGR

The study area of BGR for the first phase of SASSCAL will be the Cuvelai-Etosha-Basin (CEB) in northern Namibia. This transboundary basin (shared almost equally by area between Namibia and Angola) is home to a majority of the rural population and has unique geological and hydrological characteristics. The aquifer system, known as Ovambo basin, differs from the surface water basin and was developed long ago since the Okavango River was still part of the surface water basin (Miller, et al., 2010). An already existing infra-structure, such as boreholes from earlier BGR projects and results of geophysical investigations, qualifies the chosen basin as an ideal site and starting point for scientific investigations dealing with the complex interaction between aquifer systems, as well as groundwater recharge processes in the unsaturated zone. At a later stage the developed methodological approaches will be transferred to other study areas (Upper Zambezi Basin).

Ongoing BGR projects Groundwater for the north of Namibia and Kalahari, support expertise for the BGR team in this basin, where the majority of Namibians live (Lindenmaier et al., 2012).

Literature:

Doctoral Theses

• BEYER, M. (2016): Quantitative studies along the soil – vegetation – atmosphere interface of water – limited environments: practice-oriented approaches based on stable water isotopes, modeling and multivariate analysis. Mitteilungen des Instituts für Wasserwirtschaft, Hydrologie und landwirtschaftlichen Wasserbau, Leibniz Universität Hannover, Heft 102, ISSN 0343-8090
• GAJ, M. (2016): Recharge estimation in a (semi-)arid environment using soil water balance, stable isotopes and modeling approaches. Albert-Ludwigs-Universität Freiburg

Master Theses

• ADAM, B. (2015): Modelling the response of stable isotope fractionation in soil water profiles with uncertainty. KIT Karlsruhe.
• BAHLMANN, L. (2016): Rainfall characteristics and their implications for groundwater recharge in deep vadose zones. A case study in the Cuvelai-Etosha Basin (CEB), Namibia. Leibniz University Hannover.
• MAHINDAWANSHA, A. (2015): Intercomparison of laboratory techniques for determination of stable isotopes in soil water. University of Darmstadt.
• SCHILLING, M. (2015): Indirect groundwater recharge in the Cuvelai-Etosha Basin (CEB), Namibia. Investigating the importance of Oshanas, Deflation Pans and Ephemeral River Beds. Leibniz University Hanover.
• SHEHU, B. (2014): Correction of GRACE data for the influence of surface water, soil and vegetation moisture. A case study on the quantification of groundwater recharge rates in the Cuvelai-Etosha-Basin (CEB), Namibia. Leibniz University Hanover.
• VILLANUEVA, R. (2015): Direct groundwater recharge in Cuvelai-Etosha-Basin (CEB), Namibia. The use of DAISY for modelling unsaturated zone water movement in a semiarid climate. Leibniz University Hanover

Technical Report

• LINDENMAIER, F., DILL, H.G., DOHRMANN, R., FENNER, J., GERSDORF, U., KAUFHOLD, S., KRINGEL, R., LUDWIG, R., MILLER, R.G., NICK, A., NOELL, U. & WALZER, A. (2012): Results of Analysis from Drill Holes on the Cubango Megafan. - Technical report prepared for the Kalahari Research Project "Development and Dating of Duricrusts as Base for a Paleogeographic and Hydrogeological Model of the Cuvelai-Etosha Basin in North Namibia". 50 p.; Hannover. (PDF, 2 MB)

Papers

• BEYER, M., GAJ, M., HAMUTOKO, J., KÖNIGER, P., WANKE, H. & HIMMELSBACH, T. (2015): Estimation of groundwater recharge via deuterium labelling in the semi-arid Cuvelai-Etosha Basin, Namibia. - Isot. Environ. Health Stud. 51(4): 533-552. doi: 10.1080/10256016.2015.1076407
• BEYER, M., GAJ, M., KÖNIGER, P., HAMUTOKO, J.T., WANKE, H., WALLNER, M. & HIMMELSBACH, T. (2018): Isotopenhydrologische Methoden (²H, ¹⁸O) zur Bestimmung der Grundwasserneubildung in Trockengebieten: Potenzial und Grenzen. - Grundwasser 23(1): 73-90. doi: 10.1007/s00767-017-0381-0
• BEYER, M., KÖNIGER, P., GAJ, M., HAMUTOKO, J.T., WANKE, H. & HIMMELSBACH, T. (2015): A Deuterium-based labeling technique for the investigation of rooting depths, water uptake dynamics and unsaturated zone water transport in semiarid environments. - J. Hydrol. 533: 627-643. doi: 10.1016/j.jhydrol.2015.12.037
• GAJ, M., BEYER, M., KÖNIGER, P., WANKE, H., HAMUTOKO, J. & HIMMELSBACH, T. (2016): In situ unsaturated zone water stable isotope (²H and ¹⁸O) measuements in semi-arid environments: a soil water balance. - Hydrol. Earth Syst. Sci. 20: 715–731. doi: 10.5194/hess-20-715-2016
• GAJ, M., KAUFHOLD, S., KÖNIGER, P., BEYER, M., WEILER, M. & HIMMELSBACH, T. (2017): Mineral mediated isotope fractionation of soil water. - Rapid Commun. Mass Spectrom. 31(3): 269-280. doi: 10.1002/rcm.7787
• HAMUTOKO, J.T., WANKE, H., KÖNIGER, P., BEYER, M., GAJ, M. (2017): Hydrogeochemical and isotope study of perched aquifers in the Cuvelai-Etosha Basin, Namibia. - Isotopes Environ. Health Stud. 53(4): 382-399. doi: 10.1080/10256016.2016.1273913
• HIMMELSBACH, T. (2017): Tiefe, semi-fossile Grundwasserleiter im südlichen Afrika: Hydrogeologische Untersuchungen im Norden von Namibia. - GMIT – Geowiss. Mitt., 67: 7 - 18. (PDF, 4 MB)
• KÖNIGER, P, GAJ, M., BEYER, M. & HIMMELSBACH, T. (2016): Review on soil water isotope-based groundwater recharge estimations. - Hydrol. Process. 30: 2817-2834. doi: 10.1002/hyp.10775
• WALLNER, M., HOUBEN, G., LOHE, C., QUINGER, M., HIMMELSBACH, T. (2017): Inverse modeling and uncertainty analysis of potential groundwater recharge to the confined semi-fossil Ohangwena II Aquifer, Namibia. - Hydrogeol. J. 25: 2303-2321. doi: 10.1007/s10040-017-1615-z
  

Presentations

• BEYER M. et. al. (2017): Drought-induced anomalies of soil water stable isotopes enable identification of deep root water uptake. German Association for Stable Isotope Research (GASIR) - Meeting, Hannover, Germany
• BEYER M. et. al. (2017): Ecohydrological feedbacks in water-limited environments: combining drought-induced changes of soil water stable isotopes and labeling experiments, International workshop on “Isotope-based studies of water partitioning and plant-soil interactions in forested and agricultural environments”, Florence, Italy
• BEYER M. et. al. (2015): Deuterium (²H) as applied tracer in the vadose zone: experiences from semiarid Namibia. German Association for Stable Isotope Research (GASIR) - Meeting, Heidelberg, Germany
• BEYER M. et. al. (2014): Artificial deuterium labeling for a quantification of groundwater recharge in semi-arid regions. German Association for Stable Isotope Research (GASIR) - Meeting, Munich, Germany (PDF, 63 KB)
• GAJ, M. et. al. (2015): Limits and potentials determining stable water isotopes using in-situ measurements and soil water extractions. German Association for Stable Isotope Research (GASIR) - Meeting, Heidelberg, Germany (PDF, 48 KB)
• GAJ, M. et. al. (2014): Isotopic enrichment of stable isotopes (2H and 18O) in the soil-plant-atmosphere continuum: Implications for seasonal water uptake and evaporation patterns in a semi-arid environment. IAH-International Congress; Marrakech, Marocco (PDF, 113 KB)
• KÖNIGER, P. et. al. (2014): Soil water stable isotope based groundwater recharge estimations: Examples from humid and semiarid areas. IAH-International Congress, Marrakech, Marocco (PDF, 101 KB)

Posters

• BEYER, M. et. al. (2017): Constraining water uptake depths in semiarid environments using water stable isotopes. EGU General Assembly, Vienna, Austria
• BEYER M. et. al. (2016): Inferring root water uptake depths from water stable isotopes at different system states: Combining natural abundances and labeling experiments. Joint European Stable Isotopes User group Meeting (JESIUM), Ghent, Belgium
• BEYER, M. et. al. (2014): Deuterium labeling of soil water movement in the Cuvelai-Etosha Basin, Namibia. EGU General Assembly, Vienna, Austria (PDF, 1 MB)
• GAJ, M. et. al. (2016): How do soil types affect stable isotopes ratios under evaporation: A post corrected evaporation fingerprint of the Cuvelai-Etosha-Basin, Namibia. Joint European Stable Isotopes User group Meeting (JESIUM), Ghent, Belgium (PDF, 1 MB)
• GAJ, M. et. al. (2016): Stable isotopes of soil water are affected by clay minerals: A post correction approach for dry soils based on physicochemical soil properties. EGU General Assembly, Vienna, Austria
• GAJ, M. et. al. (2015): In-situ measurements of pore water stable isotope composition in a semi-arid environment and their implications to spatio-temporal variability. EGU General Assembly, Vienna, Austria (PDF, 3 MB)
• GAJ, M. et. al. (2015): Modeling unsaturated zone water stable isotope depth profiles in an evaporation dominated environment. IAH-Internaltional Congress, Rome, Italy (PDF, 5 MB)
• GAJ, M. et. al. (2014): How do soil types affect stable isotope ratios of 2H and 18O under evaporation: A Fingerprint of the Niipele subbasin of the Cuvelai - Etosha basin, Namibia. Proceedings of EGU General Assembly, Vol. 16, Vienna, Austria (PDF, 45 KB)
• GAJ, M. et. al. (2014): Recharge estimation in a semi-arid environment using stable isotope methods: A discussion on in-situ field and laboratory techniques. German Association for Stable Isotope Research (GASIR) - Meeting, Munich, Germany (PDF, 4 MB)
• KÖNIGER, P. et. al. (2014): Stable isotope and hydro chemical variability along the Calueque-Oshakati Canal in the Cuvelai-Etosha Basin, Namibia. EGU General Assembly, Vienna, Austria (PDF, 9 MB)

Further Literature

• MENDELSOHN, J., JARVIS, A., & ROBERTSON, T. (2013): A profile and atlas of the Cuvelai-Etosha Basin. - 170 p.; RAISON & Gondwana Collection, Windhoek, Namibia. ISBN: 978-99916-780-7-8
• MILLER, R. M., PICKFORD, M., & SENUT, B. (2010): The geology, paleontology and evolution of the Etosha Pan, Namibia: Implications for terminal Kalahari deposition. South African Journal of Geology, 113(3): 307–334.

Movie

• Namibia's Groundwater Treasure - The SASSCAL-Project & Technical Cooperation (30 min, in German)

Partner:

• Dr. Heike Wanke and Dr. Martin Hipondoka, Faculty of Geography, University of Namibia, Windhoek, UNAM

Promotion / document number:

SASSCAL / 01LG1201L