The contribution of direct moisture deposition from clouds to the hydrologic budget of high catchments in southern Colombia and possible impacts of forest removal.

Supervisor(s) : Dr. John Pitman and Dr. Mark Mulligan, Department of Geography, King's College London

In cloud forest, an extremely high surface area of vegetation resulting from high leaf areas and the presence of dense epiphytic mats, acts as an efficient trap for moisture from cloud at ground level. Given the frequency of low clouds on the Pacific slopes of Colombia, this cloud trapping mechanism could represent a significant proportion of the hydrological budget of the region.

The student will develop techniques for the measurement of volumes of input from direct cloud deposition. The contribution of this mechanism to hydrological input to the Telembi catchment will be examined with the aid of satellite data and modelling techniques. Cloud deposition is not included in conventional rain gauge measurements and the development of measurement/modelling techniques for cloud deposition will allow the much more accurate representation of total precipitation in cloud forest areas - total precipitation is likely to be much higher than measured rainfall indicates.

From an environmental change point of view, deforestation can have a significant impact in reducing river discharge and hydrological resources because grassland is likely to trap much less cloud than the high surface area cloud forest. Quantification of this reduction is precipitation through field experiment and numerical modelling is the objective of this thesis.

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