Regression Models of Soil and Water Losses from Various Erosion Control Measures in Mae Sa Integrated Watershed and Forest Land-use Project, Chiang Mai

Abstract

Regression models representing factors influencing soil and water losses from no measures plot (CK), contour bund (CB), hillside ditch (HD), intermittent terrace (IT), and bench terrace (BT) were derived from 305 storm rainfalls collected from 3 replications of 5×20 runoff plots at Mae Sa Integrated Watershed and Forest Land-use Project, Chiang Mai during 1980-1990. Stepwise regression analysis indicate only storm rainfall (Rs) significantly influenced on storm runoff (Q_s) in each of all conservation measures with R² less than 0.5 for either linear or non-linear models. There was no any parameter (R_s, and age of plot, A) meet statistical criteria for Q_s in annual prediction basis. In determining sediment concentrations from plot (S), R_s and Q_s significantly influenced on strom sediment yield (S_s) either in linear or non-linear multiple regresion but with R² ranges from 0.3972-0.7267. Age of erosion control measures shows insignificant influence on soil erosion. In annual basis, there was no factor significantly influence on erosion prediction.