Impacts of land cover change scenarios on storm runoff generation: a basis for management of the Nyando Basin, Kenya
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Date
2012
Authors
Olang, L. O.
Kundu, P.M.
Ouma, G.
Furst, J.
Journal Title
Journal ISSN
Volume Title
Publisher
Wiley Online Library
Abstract
The effects of conceptual land cover change scenarios on the generation of storm runoffs were evaluated in the Nyando Basin. The spatial
scenarios represented alternatives that vary between full deforestation and reforestation. Synthetic storm events of depths 40, 60 and
80mm were formulated according to the rainfall patterns and assumed to have durations corresponding to the runoff times of concentration.
The Natural Resource Conservation Service–Curve Number model was used to generate runoff volumes within the sub-catchments, which
were subsequently routed downstream to obtain effects in the whole basin. The simulated land cover change impacts were evaluated relative
to values obtained from the actual land cover state of the basin in the year 2000. From the results, an agricultural land cover scenario constituting
of about 86 per cent of agriculture indicated increased runoff volumes in the entire basin by about 12 per cent. An agricultural-forested
land cover scenario with 40 and 51 per cent of forest and agriculture respectively revealed reduced runoff volumes by about 12 per cent.
Alternatively, a scenario depicting a largely forested land cover state with about 78 per cent of forests reduced the runoff volumes by about
25 per cent according to the model estimates. Runoff volumes in the basin were also likely to reduce by about 15 per cent if the appropriate
land cover scenario for the respective sub-catchments were to be assumed for runoff management purposes. Considering the prevalent data
uncertainty, the study effectively highlights the potential hydrological vulnerability of the basin. The results obtained can form a basis for
appropriate catchment management of the area.
Description
Publisher version (Wiley Online)Hydrological Processes
Volume 25, Issue 1, pages 80–89, 1 January 2011
Keywords
land cover change, conceptual scenario, hydrological model, synthetic storm, runoff event, Nyando Basin, catchment management, Kenya
Citation
Land degradation & development (2012)