A Hierarchical Multi-Level Method for Spatially Assessing Soil Erosion : The Case of Kiambu District in Kenya

Knowledge and practice are invoked to organise the landscape system into hierarchical levels through the use of aerial photo analysis, remote sensing, GIS and ground measurements. Systematic and hierarchical erosion processes are studied, assessed, measured and mapped. The conceptual model revolves around the modelling of hierarchical levels in a landscape system continuum based on erosion process magnitudes. Hierarchical construction of the landscape system allows an ordered organisation of the landscape components into superordinate and subordinate parts which correspond to erosion process time-scales and their corresponding spatial extents. The organization allows relevant observations and measurements to be made. The concept deviates from viewing the landscape as a linear plane where soil erosion processes occur presumably in a uniform manner, the method identifies 'individual' landscape elements in each level of the landscape hierarchical construction where processes occur within comparable time scales, energy magnitudes and for which data interchange and modelling can take place. They are termed 'holons'.