Water quality and health in a Sahelian semi-arid urban context: an integrated geographical approach in Nouakchott, Mauritania

Access to sufficient quantities of safe drinking water is a human right. Moreover, access to clean water is of public health relevance, particularly in semi-arid and Sahelian cities due to the risks of water contamination and transmission of water-borne diseases. We conducted a study in Nouakchott, the capital of Mauritania, to deepen the understanding of diarrhoeal incidence in space and time. We used an integrated geographical approach, combining socio-environmental, microbiological and epidemiological data from various sources, including spatially explicit surveys, laboratory analysis of water samples and reported diarrhoeal episodes. A geospatial technique was applied to determine the environmental and microbiological risk factors that govern diarrhoeal transmission. Statistical and cartographic analyses revealed concentration of unimproved sources of drinking water in the most densely populated areas of the city, coupled with a daily water allocation below the recommended standard of 20 l per person. Bacteriological analysis indicated that 93% of the non-piped water sources supplied at water points were contaminated with 10-80 coliform bacteria per 100 ml. Diarrhoea was the second most important disease reported at health centres, accounting for 12.8% of health care service consultations on average. Diarrhoeal episodes were concentrated in municipalities with the largest number of contaminated water sources. Environmental factors (e.g. lack of improved water sources) and bacteriological aspects (e.g. water contamination with coliform bacteria) are the main drivers explaining the spatio-temporal distribution of diarrhoea. We conclude that integrating environmental, microbiological and epidemiological variables with statistical regression models facilitates risk profiling of diarrhoeal diseases. Modes of water supply and water contamination were the main drivers of diarrhoea in this semi-arid urban context of Nouakchott, and hence require a strategy to improve water quality at the various levels of the supply chain.

Defining and measuring urban regions: A sensitivity analysis

This paper evaluates the impact of alternative city boundary definitions on economic performance. First we discuss the theoretical background and motivate the empirical work. Then we present the methodological concept of the sensitivity analysis, which will be applied to a variety of data of Zurich and Bern (the financial and the administrative centres of Switzerland) in order to see how the values of different indicators vary depending on the definition adopted. Finally we will show whether the empirical patterns found are statistically significant. The analysis shows, that the delimitation of a city or city region indeed matters.

Urban expansion and its impact on urban agriculture – remote sensing based change analysis of Kizinga and Mzinga Valley – Dar Es Salaam, Tanzania

Urban agriculture is a phenomenon that can be observed world-wide, particularly in cities of devel-oping countries. It is contributing significantly to food security and food safety and has sustained livelihood of the urban and peri-urban low income dwellers in developing countries for many years. Population increase due to rural-urban migration and natural, coupled with formal as well as infor-mal urbanization are competing with urban farming for available space and scarce water resources. A multitemporal multisensoral urban change analysis over the period of 25 years (1982-2007) was performed in order to measure and visualize the urban expansion along the Kizinga and Mzinga valley in the South of Dar es Salaam. Airphotos and VHR satellite data were analyzed by using a combination of a composition of anisotropic textural measures and spectral information. The study revealed that unplanned built-up area is expanding continuously and vegetation covers and agricultural lands decline at a fast rate. The validation showed that the overall classification accuracy varied depending on the database. The extracted built-up areas were used for visual in-terpretation mapping purposes and served as information source for another research project. The maps visualize an urban congestion and expansion of nearly 18% of the total analyzed area that had taken place in the Kizinga valley between 1982 and 2007. The same development can be ob-served in the less developed and more remote Mzinga valley between 1981 and 2002. Both areas underwent fast changes where land prices still tend to go up and an influx of people both from rural and urban areas continuously increase density with the consequence of increasing multiple land use interests.

Fostering sustainable urban development in Nakuru, Kenya Rift Valley

The town of Nakuru—Kenya's fourth largest town—lies in a unique setting in the Great Rift Valley. Recent developments on the Menengai Crater, the Mau Escarpment, and the Bahati Highlands exemplify the impacts of poorly planned urban growth on mountain ecosystems. The Nakuru Local Urban Observatory (LUO) project was initiated by the Municipal Council of Nakuru in January 2003, in collaboration with the Centre for Development and Environment (CDE) of the University of Berne and the Intermediate Technology Development Group (ITDG), and with funding from the Swiss Agency for Development and Cooperation (SDC). The project aims to provide a framework for sustainable urban development practices by building technical skills and improving participation by local stakeholders in decision-making processes. The potentials of information technology (IT) are being tapped to provide up-to-date information to decision-makers and democratize access to information, in order to improve public participation. The overall objective is to find ways of achieving better urban management in order to mitigate non-sustainable development trends in the town and its surroundings.