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Asian Journal of Agriculture and Development (AJAD) - Call for papers!

Some Erosion Parameters in a Grassland Cover at Selected Slope Degrees and Lengths

(Philippines), Master of Science in Forest Resources Management (University of the Philippines Los Baños)

Thesis Abstract:

The relationship of soil loss and runoff parameters to the degree and length of slope under the conditions of grassland cover were evaluated.

Twenty-four 1-m wide runoff plots were established on selected slopes for the study. Among other measurements, soil loss and runoff were monitored daily with each occurrence of runoff producing rainfall.

Based on the average of slope degrees and lengths used in the study and using the data accompanying the 25 runoff-producing rainfall, linear correlation and regression methods were used to analyze soil loss in relation to runoff, amount of rainfall, and percent runoff of rainfall. Likewise, runoff in relation to the amount of rainfall was analyzed. Split-plot design analysis of variance, multiple regression, and correlation techniques were used to evaluate the effects of slope degree and length on soil loss and runoff. Regression equations for soil and runoff as functions of the degree and length of slope were developed.

On field-plot basis, soil loss per unit area was found to be significantly associated with such variables as runoff, amount of rainfall, and percent runoff. Similarly, runoff was significantly related to the amount of rainfall.

The magnitudes of soil loss and runoff per unit area were found to be significantly affected by the degree and length of slope. Soil loss and runoff per unit area increased with an increase in the degree of slope. However, soil loss and runoff decreased with and increase in the length of slope.

The empirical relationships derived for soil loss and runoff as functions of slope degree and length as used in this study could offer tentative usefulness on sites of similar slope, soil, and climatic conditions. However, it was recommended that further investigations be undertaken on more diverse field conditions to develop and improve the applicability of these relationships.