Wasserversorgung und Wasserhaushalt in Trockengebieten Namibias

Abstract

Summary provided by author:

The scarcity of water in Namibia illustrates the inevitable consequences of any present or preceding unbalanced human impact on the water cycle of drylands: a rapidly growing water demand for domestic, agricultural and industrial purposes is progressively endangering any sustainable water resources management for Namibia. In order to facilitate a sufficient freshwater supply to the public, the Namibian Department of Water Affairs needs to collect reliable data on the current consumption and to carry out an evaluation of the medium and long-term perspective on the availability of freshwater. The Namibian hydro-environments are predominantly characterized by dryland conditions. According to hydrological figures provided by the Namibian Department of Water Affairs the estimated freshwater consumption in 1993 equals a grand total of 265 million cubic meters, of which 57 percent originate from groundwater, 22 percent from perennial surface water, and 21 percent from ephemeral rivers. Reliable hydrological baseline information is currently available for some selected catchments and sub-catchments, but does not cover the entire national water resources. New techniques in collecting hydro-environmental baseline information, such as the application of satellite-based remote sensing data and digital image processing, provide significantly more and also more reliable data than the traditional ones solely operating with conventional means and methods

The Omaruru catchment, situated in central-western Namibia, was selected as a test area for the presented feasibility study on the application of the above-mentioned new techniques. The test site is a typical dryland environment characterized by an ephemeral runoff regime and distinct features of surface flow and interflow patterns. In the Omaruru catchment satellite image processing was tested for the assessment of relevant catchment parameters. The hydro-environmental situation of the Namibian ephemeral rivers is identified to be highly variable in space and time. In order to determine the water balance a regionalization of the hydro-dynamics becomes compulsory. Besides, Namibian catchments show considerable spatial dimensions

Taking that into account, this study introduces a new methodological approach in order to meet present and future requirements of any water resources management. Based on a parallel approach combining both digital satellite image processing and conventional field work, the study demonstrates the advantages of image processing in analyzing the catchment parameters of drylands. The regional classification of climatic, topographic and geological factors as well as land-use patterns and hydro-ecological risk potentials provides an adequate information level for any water-related planning purpose and / or decision making

The data and the scientific outcome of this study represent an information platform that can be considered as hydro-enviromental baseline or geohydrological key-information for any further predictive modelling of water resources in catchments adjacent to the Omaruru River, such as for the all other west-flowing ephemeral rivers north of the Kuiseb