Hans-Jürgen Voigt

Vulnerability of water resources in northern Cameroon in the context of climate change

Water resources in northern Cameroon have continuously been reducing over the past years. Many studies have suggested two principal causes: (1) human activities such as poor farming practices, unsustainable use of water resources, increased demand of water, deforestation, land-use change, etc., (2) human-induced climate change. Northern Cameroon in this study includes: the Adamawa, North and Far North regions located closer to the Sahel regions of Africa. These regions are already water stressed because of their location and any further change in climate with rising temperature would impact water resource either positively or negatively. Time series analysis and a 12-month standardized precipitation index (SPI12) with digital data between 1957 and 2006 were used to investigate the variation of water resources in northern Cameroon. Results obtained varies between the different regions with an increased annual trend in temperature and precipitation for Ngaoundere (Adamawa region) and Garoua (north region), whereas Maroua (far north region) had a decreased annual trend in both precipitation and temperature. Further variability results obtained from a SPI12 show that wetter period out number drought period in all three regions. The study concluded that water resources vary with the changing climatic condition and the severity of the impact varies from region to region. Furthermore, water deficiency in northern Cameroon might not be due to climate change. The reasons might be a combination of poor water management and other factors such population growth, the environmental condition, etc.

Joint Research Project Brine: Carbon Dioxide Storage in Eastern Brandenburg: Implications for Synergetic Geothermal Heat Recovery and Conceptualization of an Early Warning System Against Freshwater Salinization

Brine was a scientific joint-project implemented to accompany a prospective CO2 storage site in Eastern Brandenburg, Germany. In this context, we investigated if pore pressure elevation in a CO2 storage reservoir can result in shallow freshwater salinization involving the conceptual design of a geophysical early warning system. Furthermore, assessments of a potential synergetic geothermal heat recovery from the CO2 storage reservoir and hydro-mechanical integrity were carried out. The project results demonstrate that potential freshwater salinization is strongly depending on the presence and characteristics of geological weakness zones. The integrated geophysical early warning system allows for reliable monitoring of these potential leakage pathways at different spatial and time scales.

Methods for Characterizing the Geochemical and Microbiological Conditions

A geochemical investigation in the study area should be primarily focused on characterizing the complex chemical inventory of the groundwater, surface water, soil, rock, stream and lacustrine sediments, and soil gas. Geochemical site characterization includes a determination of geogenic background values and anthropogenic input. This distinction is possible only if the size of the area and the number of sampling points is adequate for a statistical evaluation. A geochemical investigation usually takes place following the geological, hydrogeological and geophysical surveys, the results of which are used for a focused and representative sampling strategy. The approach and the scope of a geochemical site investigation depend on the following: the objective and phase of the investigation, the contamination potential, the compartment under consideration (e.g., the groundwater, soil, or air), and the natural environmental conditions.

Beschaffenheitsmuster des Grundwassers im Lockergestein

Die Beschaffenheitsentwicklung des Grundwassers auf allen Etappen seiner Formierung, beginnend in der Atmosphare bis zu den tiefsten Teilen der unterirdischen Hydrosphare, wird durch eine Vielzahl von komplizierten, voneinander unabhangigen, zufalligen und in jedem Fall jedoch den konkreten Standortbedingungen entsprechenden Prozessen und Faktoren bestimmt. Dabei mus dem Umstand Rechnung getragen werden, das das Grundwasser mit seinen gelosten Inhaltsstoffen nur einen Bestandteil des „Mehrphasensystems Untergrund“, d.h. des zeitlich und raumlich veranderlichen Systems „Wasser-GesteinGas-Biomasse”, darstellt. Folglich ist die an einem hydrogeologischen Aufschlus (Brunnen, Grundwassermesstelle, Quelle etc.), in einem bestimmten Grundwasserleiter, innerhalb einer geologischen Struktur, ermittelte Grundwasserbeschaffenheit sehr unterschiedlich und last sich nach verschiedenen Gesichtspunkten typisieren, klassifizieren, gruppieren bzw. regionalisieren. Ausdruck dieser Vielfalt ist die grose Anzahl hydrogeochemischer Typisierungs-und Klassifizierungsverfahren (mehr als 150), die in der Literatur beschrieben wurden (→ Kap. 20). Im Rahmen der regionalen Beschaffenheitsbetrachtung der Grundwasser in den Lockergesteinen Brandenburgs wird im folgenden ein Bewertungsverfahren vorgestellt, das naturraumliche Bezugssysteme zur Erklarung der GW-Beschaffenheit berucksichtigt.

Comparative Analysis of Environmental and Social Impacts of Cocoa Production: Case Study Cameroon

During the late 1980s, the Cameroonian cocoa sector was controlled by the government in their attempt to stabilise farm income by setting an average purchase price for raw cocoa. This system collapsed around 1987, when there was a drastic fall in the world price of cocoa and the government could not stabilise the market using its traditional support systems of setting an annual purchase price. In 1994/1995 the Cameroon cocoa trade was fully liberalised (Bisseleua 2007). According to the Ministry of Agriculture and Rural Development, the Sixth International Cocoa Agreement which came into force in 2003, inspired the adoption of Law No. 2004/025 on 30th December 2004 that liberalised the country’s cocoa sector (UNEP 2009). In this law, issues such as product quality and their derivatives, the collection, analysis and dissemination of data were addressed. Additionally, compliance with international standards for future production was also ensured by the law.

Methods for Characterizing the Geological Setting

Site investigations and assessment require a thorough understanding of the geology of the site. The following aspects or parts thereof must be taken into account: stratigraphic sequence, thickness and lateral extent of strata and other geological units, lithology, homogeneity and heterogeneity, bedding conditions, tectonic structures, fractures, and impact of weathering. Information about landforms (geomorphology), earthquake risk, activity of faults, land sliding, subsidence and caving to the surface as a result of mining and karst must also be collected. Planning of an investigation must take into account accessibility, whether the surficial rock is unconsolidated or consolidated and the investigation methods must be appropriate for the geological/hydrogeological conditions.

Methods for Characterizing the Hydrologie and Hydraulic Conditions

Hydrology is science of the behavior of water in the atmosphere, on the Earth’s surface, and in the subsurface, while the hydrogeology studies the groundwater and its relationship to the geologic environment. Both points of view are important in a site investigation and assessment. Basic in hydrology is the hydrologic cycle, also known as the water cycle, i.e. the continuous circulation of water between the atmosphere, land, surface water, groundwater, and plants, through condensation, precipitation, runoff, infiltration, evaporation, transpiration, groundwater flow, storage and seepage. Figure 5.2-1 shows the elements of the hydrologie cycle. The hydrologie cycle supplies terrestrial organisms with freshwater and is therefore a source of life. The system powered by solar radiation determines essentially the climate.

Interpretation of Geological, Hydrogeological, and Geochemical Results

Almost all data obtained in geoscientific investigations need some kind of statistical treatment for interpretation, as well as for the assessment of reliability and errors. The following statistical methods are frequently used to analyze data sets: • univariate analysis, i.e., analysis of an individual parameter (e.g., concentration of a substance, pH, or electrical conductivity at several locations), • multivariate analysis, i.e., analysis of several parameters together, to determine the relationship between parameters (e.g., the relationship between concentrations of different substances and/or of several environmental parameters), and • time series analysis (e.g., analysis of a parameter as a function of time, for example, monitoring of water level or the concentration of a substance in a groundwater observation well).

Methoden zur Erfassung und Bewertung der Schadstoffemissionen

Die Abgrenzung anthropogener Beeintrachtigungen auf den Ausbreitungspfaden stellt eines der grundlegenden Erkundungsziele der Standortuntersuchungen dar. Eine wesentliche Voraussetzung zum Erkennen dieser Beeintrachtigungen ist die Kenntnis der naturlichen Hintergrundgehalte in Wasser und Boden. Die Erkundungspraxis der letzten Jahrzehnte zeigt, das die Erkundung von Altablagerungen und Altstandorten weniger von der Philosophie des Vergleichs mit den naturlichen Hintergrundwerten als vielmehr von einer formalen Anwendung der in den Bundeslandern entwickelten Grenzwertlisten gepragt ist. Mit der „Empfehlung zur Erkundung, Bewertung und Sanierung von Grundwasserschaden“ der LAWA (1994), die im Oktober 1993 von der Umweltministerkonferenz verabschiedet wurde, liegt erstmals ein fur die gesamte Bundesrepublik verbindliches Dokument vor, in dem gefordert wird, das die konkreten geochemischen Verhaltnisse im Umfeld in die Bewertung einzubeziehen sind. Obwohl uber die ausgewiesenen Mindestanderungen am Untersuchungsstandort im Vergleich zum Hintergrund diskutiert werden kann (z. B. NH4 + im Grundwasser + 0,3 - was unter der naturlichen Schwankungsbreite liegt) ist die Orientierung auf eine okosystemare Betrachtungsweise zu begrusen.