Efficiency of various soil and water conservation practices on hillslope at Mae Sa Integrated Watershed and Forest Land use Project, Changwat Chiang Mai
1995
Aphinan Khorporn
Efficiency of four soil and water conservation measures namely contour bund (CB), hillside ditch (HD), intermittent terrace (IT) and bench terrace (BT) determined by P-factor in the Universal Soil Loss Equation (USLE) was evaluated using soil loss observed from three replications of 5*20 runoff plots in the Mae Sa Integrated Watershed and Forest Land Use Project, Changwat Chiang Mai. Observed soil and water losses during 1980 to 1990 were employed in the study. The efficiency (P-factor in USLE) was calculated as the ratio of soil loss from each conservation practice and that of check plot (CK). Results showed that P-factor for CB, HD, IT and BT was 0.214, 0.299, 0.245 and 0.128 respectively. The same manner of erosion control efficiency was derived when P-factor was determined basing on 1 mm of runoff in the respective plots. Relationship between storm runoff and storm rainfall indicated by coefficient of determination (R*[2)) was less than 0.50 for all measures. The same pattern of (R*[2)) was also obtained for the relationship between soil loss and storm rainfall but increasing with highly significant when surface runoff and age of the measures were added in the prediction equations.
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