Modeling hydrological response to land use change in watersheds of viti levu island, fiji

Effective watershed management and ecological restoration require a thorough knowledge of the hydrological processes going on in the watersheds. The impact of land use/land cover change over a 14 year period and human alterations on hydrological regimes of large catchments of Viti Levu, Fiji, was investigated with spatial and temporal datasets using hydrologic simulation model, coupled with remote sensing techniques and geographic information system. The SWAT (Soil and Water assessment Tool) model was found to be useful in identifying the effect of land use changes on hydrological properties and changes of water balance components for five major watersheds of Viti Levu, Fiji. Given the complexities of the river basins and the large number of interactive processes taking place simultaneously and consecutively at different times and places within the study area, it is believable that the simulated results comply with the measurements satisfactorily. More importantly this study revealed that land use/land cover plays a dominant role in changing basin hydrology. The resulting predictions of annual hydrological response for the year 1992, 1999, 2003 and 2007 indicate that the greatest impact of land use change was on the amount of surface runoff. The increased surface runoff can be attributed to the fact that in 2007 the soil was poorly covered or even bare, so interception was lower and the curve number higher than in the reference year 1993. This watershed scale analysis is important to provide significant information on the hydrological consequences of land use/cover practices and climate trends with the accompanying implication on surrounding coastal ecosystem health.

Land use ,

Runoff ,

Hydrological response ,

Remote Sensing ,

SWAT ,