Spatial expansion and water requirements of urban agriculture in Khartoum,Sudan |
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| Authors: | J. Schumacher E. Luedeling J. Gebauer A. Saied K. El-Siddig A. Buerkert |
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| Affiliation: | 1. Organic Plant Production and Agroecosystems Research in the Tropics and Subtropics, University of Kassel, Steinstraße 19, 37213 Witzenhausen, Federal Republic of Germany;2. Department of Plant Sciences, University of California, Davis, USA;3. Agricultural Research Corporation, Wad Medani, Sudan;1. Animal & Grassland Research and Innovation Centre, Teagasc, Grange, Dunsany, Co. Meath, Ireland;2. School of Biology and Environmental Science, University College Dublin, Belfield, Dublin 4, Ireland;1. School of Earth and Ocean Sciences, Cardiff University, United Kingdom;2. School of Geography and Geosciences/Scottish Oceans Institute, University of St Andrews, United Kingdom;1. INRA-AGIR, Université de Toulouse, UMR1248, BP 52627, F-31326, Castanet-Tolosan Cedex, France;2. Tuscia University, Department of Agricultural and Forestry Sciences (DAFNE), Via San Camillo de Lellis, I-01100 Viterbo, Italy;3. Via A. Di Tullio 40, I-00136 Rome, Italy;4. Council for Agricultural Research and Economics, Research Centre for Forestry and Wood, Viale Santa Margherita 80, I-52100 Arezzo, Italy;1. Department of Architecture, Faculty of Engineering, Cairo University, Egypt;2. Department of Architecture and Civil Engineering, University of Bath, UK;3. School of Civil Engineering, University of Leeds, UK;4. Department of Urban Studies, Malmö University, Sweden;5. Department of Architecture, Design and Media Technology, Aalborg University, Denmark |
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| Abstract: | Urban agriculture (UA) in Khartoum, Sudan, contributes to meeting the increasing food demand of the city's rapidly growing population, but its spatial extent, development over time and resource consumption are unknown. To fill this knowledge gap, we analyzed scenes captured by Landsat satellites in 1972, 1987 and 2000. For each dataset, we calculated the Normalized Difference Vegetation Index (NDVI) and classified all grid cells with NDVI values higher than one standard deviation above the mean as vegetated land. We also quantified agricultural vegetation on aerial photographs taken in 1958 and on a recent Google Earth image. The built-up area of the city was estimated for each point in time. Based on these spatial estimates, we computed water consumption by UA based on geographic, temporal and climatic datasets and official data on the cropping patterns of Khartoum State, using the Penman–Monteith equation to estimate crop water demands, and assuming a water use efficiency of 0.56.Urban agriculture increased from 8751 ha in 1972 to 13,249 ha today. In the municipal core zone, UA decreased from 4799 ha in 1958 to 2869 ha today. Along the Nile, UA persisted through time, whereas many urban irrigation schemes have been pushed into the periphery. The built-up area increased strongly and today exceeds the UA area 5.5-fold. Estimated crop water demand on UA land increased from 241 to 365 million m3 year?1 between 1972 and today. |
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