A HYDROLOGICAL APPROACH TO TROPICAL FORESTATION: CONTROVERSIAL ISSUES AND POSSIBLE APPLICATIONS OF TOPOGRAPHIC-WETNESS MODELS

Abstract

This paper provides a state of art in the field of hillslope hydrology in respect to knowledge and representation of soil moisture patterns across a river basin. It is a field-orientated review which argues for a stronger input of hydrological sciences in land and forest management. It will outline the elementary aspects of topographic-wetness models which could be linked with various forestation strategies of degraded land within a drainage basin context. An implicit assumption is that there are very limited hydrological data bases available within the humid tropics. Nonetheless, these models can be applied provided detailed topographic information is available which enables the estimation of topographic or wetness indices. An alternative, experimental approach of "gauging" the spatial soil moisture pattern is proposed. A succinct coverage of the relevant hydrological processes is given and linked to the controversial hydrological issue of reports of increased flooding and conversely decreased low flows within streams emanating from degraded lands. The role of forestation in this controversial issue will be highlighted. A considerable proportion of this work was devoted towards the restoration ecology community gaining a better appreciation of the application of topographic-wetness models within the above integrative drainage basin context.