Project Monitoring Network
Experts in water resources management point out the difficulties in water management projects in their publications and in their lectures at conferences.
They underline that national and international organisations of development cooperation often have the problem that no or insufficient hydrological and meteorological data are available. But these data are of great importance for reliable calculations in the areas of
- agriculture (irrigation and drainage, desalination of soil)
- housing water management (water supply and sanitation)
- erosion control
- flood protection
- water balance
- nature conservation (establishment of borders for marshlands, nature reserves, national parks)
- energy industry
- rural and urban measures (road and path construction, sewerage systems)
Water deposits usable for these purposes are often not recorded in quantity, quality, their geographical and seasonal allocation. Frequently, available data have gaps. Professor Dr.–Ing. H. Wildenhahn is describing this in his reference book “Wasserwirtschaftliche Meß- und Auswerteverfahren in Trockengebieten”, published by DVWK in 1990 .
That this situation has not changed until today becomes clear in the report “Data shortage in Africa”, by Volker Mrasek in “Deutschlandfunk” of 24th August, 2005. Swedish hydrologist and engineer Rikard Lidén states at a seminar at the World Water Week at Stockholm in 2005 that Africa is suffering not only from water shortage but also from data shortage. Sten Bergström, leader of the research group of the Swedish Weather and Water Service at Norrköping / Sweden is quoted with the following words: “Sometimes, data are lacking because they were never measured. Sometimes, gauging stations are destroyed during civil wars. But mostly, water departments are lacking money to employ people for measuring and maintaining the equipment. This is a real problem.” says Rikard Lidén, this is a growing problem, “since data quality is deteriorating and many measurement series are not continued nowadays. So the engineer warns that water shortage in Africa could aggravate, describing an example from the south eastern corner of the continent ...”
Before the beginning of a project
… there are the following questions and problems:
- Are there any data for the project area?
- Where can I get data for the project area?
- How reliable, representative or comparable (same measurement method) are these data?
- Can the gaps in the series of measurements be closed, e.g., by setting up separate gauging stations or by transferring data from comparable areas?
- The search for data in the country itself is highly time- and money-consuming without guarantee for success.
Even if there was enough time before the start of the project to set up gauging stations and to carry them on during the project, raised data will not have the same statistical meaningfulness as measurement series over many years. For water resources management, planning requires measured values over 10 to 30 years. The longer the period of observation time the more convincing are the results.
Comparison of Station Density in Germany and Africa
Compared to Germany, the net of hydrological and meteorological measuring stations in Africa is of low density. Thus, the covered area of each measuring station is very large and the meaning of the data correspondingly low. Illust. 1 shows the comparison of area per weather station in Africa and in Germany.
In Africa, one WMO weather station covers an area of 27,347 km². Altogether, there are 1,108 WMO weather stations on the continent. In Germany, the covered area per WMO weather station is 1,244 km². There are 287 WMO weather stations operated in Germany.
You can find a table with the number of WMO weather stations in some African countries here
In Africa (without the area of Sahara), there are 888 gauging stations in an area of 21,300,000 km². Because the Sahara is practically drain-off free, the area of the continent is reduced by that area. Illust. 2 shows the area of Africa without Sahara and that of Germany with the existing number of gauging stations.
Both illustrations clearly show at how few locations on the African continent measure hydrological and meteorological data.
|Country||Area in km²||Number of Stations¹||Area per Station in km²|
|British Islands Atlanic||2|
|Central African Republic||622,984||14||44,499|
|Democratic Republic of the Congo||2,345,410||57||41,148|
|French Islands in Indopazific||22,225||10||2,223|
|São Tomé and Príncipe||1,001||2||501|
1 Quelle: Deutscher Wetterdienst Hamburg, Stand 13.05.2008