ZLV Online

Abstrakt

Increase of run-off volume in forest catchments after vast timber harvest poses a permanent problem for forest hydrology investigation. Submitted analysis brings a new approach to solve the problem, considering the harvested area to be a complex of the full-grown forest remains, young plantation with advanced growth, and weed-infested cutovers with differentiated run-off. To study the problem, three methods were developed. The first method is based on double sum curve (DSC) model. It determines ratio of sum of run-offs from harvested areas as a complex of full-grown forest remains, young plantation with advanced growth, and clearcuts to run-off from original full-grown forest on the same territory. The second method is based on taking weights of logging into consideration. It determines ratio of run-offs from complex of young plantation with advanced growth and clearcuts to run-off from original full-grown forest. The third method is the method of separation. It solves ratio of run-offs like the second method and moreover it determines ratio of run-offs from full-grown forest to weed-infested cutovers. It was proved correctness of the theory concerning the increase of run-off from a forest after clearcutting. It is in accordance with literature cited in references. Total run-offs increased after vast clearcutting by 1.0–9.6%. Run-off from weed-infested cutovers increased, contrary to that from original full-grown forest stand, by 8–12%. In the Červík catchment the DSC model of continuous representation brought non-uniform outcome of the analysis. For explanation of the whole effect there is a lack of more detailed data, particularly of those concerning forest soil water content. Run-off from full-grown forest during dry periods was always greater than from cutovers.