Urban growth assessment around Winam Gulf of Kenya based on satellite imagery

• We use SAR imagery and stable lights maps produced by NOAA on the basis of the night-time images.
• We estimate the expansion of urban areas surrounding Winam Gulf at different scales.
• The urban feature extraction obtained at a different scale within a particular administration area from 1997 up to 2008 results in a constant growth rate.
• We highlight a period of constant growth rate between 2002 and 2006 and negative trend after 2006 and 2008.
• This method is useful to achieve the changes occurred after an environmental change in a rapid way.

Urban growth and population dynamics are among the most critical information needed for future economic development planning, natural resources allocation and environmental management. In the present work, two methods, the first based on night-time images produced by NOAA and population maps provided by Oak Ridge National Laboratory's (ORNL) LandScan, and the second one on SAR imagery, were used in order to assess the expansion of urban areas surrounding the Winam Gulf (Lake Victoria, Kenya) at different scales. In the time covered by night-time lights imagery, the study highlighted a period of constant growth rate between 2002 and 2006 and a negative trend after 2006 and 2008. This decrease may be related to two main events occurring in the study area between 2006 and 2007: the decline of the Lake Victoria level and the abnormal proliferation of the floating weeds within the Winam Gulf. Meanwhile, the urban feature extraction obtained at a different scale within a particular district from 1997 up to 2008 results in a constant growth rate. Population movements around this zone explain different dynamics that should be studied in detail in order to understand their particular roots.