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Agricultural use of wetlands is important for food security in various regions. However, land-use changes in wetland areas could alter the water cycle and the ecosystem. To conserve the water environments of wetlands, care is needed when introducing new cropping systems. This study is the first attempt to evaluate the water dynamics in the case of the introduction of rice-millet mixed-cropping systems to the Cuvelai system seasonal wetlands (CSSWs) in north-central Namibia. We first investigated seasonal changes in surface water coverage by using satellite remote sensing data. We also assessed the effect of the introduction of rice-millet mixed-cropping systems on evapotranspiration in the CSSWs region. For the former investigation, we used MODIS and AMSR-E satellite remote sensing data. These data showed that at the beginning of the wet season, surface water appears from the southern (lower) part and then expands to the northern (higher) part of the CSSWs. For the latter investigation, we used data obtained by the classical Bowen ratio-energy balance (BREB) method at an experimental field site established in September 2012 on the Ogongo campus, University of Namibia. This analysis showed the importance of water and vegetation conditions when introducing mixed-cropping to the region.

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Abstract:The Cuvelai Basin of north-central Namibia consists of unique seasonal wetlands made up of shallow pans locally known as Iishana (Oshana, singular) which form ephemeral network systems. The basin has relatively fertile soils encouraging human settlements. More than 40% of the country's population resides in the basin. Early settlers in the basin utilized indigenous knowledge to develop land use systems that were in harmony with biophysical characteristics of the area. Over the years, there has been a departure from these indigenous land use systems resulting in land management problems. A desktop study coupled with field observations was conducted to describe the indigenous land use systems of the Owambo people living in the basin, and to determine factors behind the departure and consequential impacts of this departure on sustainability of land uses. Possible ways of preventing erosion of this indigenous knowledge were given attention. The paper recommends that the Owamboindigenous land management system needs to be embedded within government policies and regulations and should be strictly enforced. There is also a need for designing strategic basin management plans that are a combination of both scientific and indigenous knowledge.