Author : Lapong, Edward R.

Summary : A study on the effect and relationship of land use patterns on runoff (average, peak, and volume), sediment yield, and pesticide loading on a watershed-scale was conducted on four selected upland microcatchments in Manupali Watershed at Lantapan, Bukidnon. Land use pattern was monitored based on land use (percentage cultivated area) and land treatment (percentage conserved area). The hydrometeorological data were monitored from January to December 2004. The runoff, sediment, and pesticide transport were measured using weir, graduated staff gages, digital flow meter, and depth integrating sediment sampler. The climatic data was monitored monthly from an Automatic Weather Station at the study site. Information on tillage practices and pesticide use were gathered using the questionnaire-interview method with farmers as respondents. The variables were analyzed using F-test Analysis of VAriance (ANOVA) and Duncan Multiple Range Test (DMRT) at significant level of 0.05. Statistical analysis showed that on a per unit area basis, runoff variables were found to be not significantly different among the catchments while sediment yield and pesticide loading were significantly different between Kiluya and Kalainigon catchments. Results of statistical analysis also showed that runoff, sediment yield, and pesticide loading were directly proportional to the percentage cultivated area and inversely proportional to the percentage conserved area indicating that an increase in land use leads to the increase in runoff, soil erosion, and pesticide transport while increase in percentage conserved area lessens the detrimental effect of such variables. The prediction equations for the runoff, sediment yield, and pesticide concentration proved to be highly acceptable with model R2 ranging from 0.818 (in Kiluya 2) to 0.964 (in KAlainigon 2). Thus, the generated equations could be used for future prediction and estimation of runoff, sediment yield, and pesticide loading.