The Effect of Deforestation on Water Quality: A Case Study in Cienda Micro Watershed, Leyte, Philippines

Deforestation has an impact on the quality of water flowing through the watershed and alters the discharge, chemical and physical properties of water. This paper presents the effect of deforestation on water quality, in particular on physical and chemical characteristics of water and evaluates the community based watershed management schemes in Buyhang micro watershed. The quality of water is assessed on the basis of laboratory analysis of various parameters by using weekly grab sampling technique from three alternative land uses and in depth assessment of farmers’ needs, priorities, and conservation practices. The farmers’ primary concerns are food security and sustained productivity. Soil erosion is not seen as a problem in the Cienda community and currently still seems to reflect stable conditions. The perception and appreciation of people towards the function of forest ecosystems is limited. People are continuously changing the forest area for abaca plantations, rice fields, and other agricultural crops in very steep slopes. There is only 0.97 ha of reforestation activity in the watershed. Most people judge the quality of water by its aesthetic properties of colour, taste, odour and turbidity. Except the agricultural water samples, the other two samples appeared colourless through visual observations. The water from undisturbed forest area is palatable and all are free of odour. The pH values of the water samples ranged within standard values. Total hardness was trace except one sample from agricultural land. Turbidity was found to be less and ranging from 5 to 22 FTU. Sediment is recorded from agricultural water samples and higher during peak flow. The highest concentrations of PO4- were measured from the forest water samples. The mean Ca++ concentrations ranged from 10 to 11.6 mg/L. There is no significant difference between the three water samples in Mg++ concentration. Total K+ was also found below 6.6 mg/L. Na concentrations were ranging from 6.5 to 8.7 mg/L. Generally, the results from this study show no significant difference between waters from forest and deforested area in terms of chemical analysis but clear contrast in physical properties. The nutrient concentration of water from the forested site is relatively higher and untypical in the case of nitrate concentrations than deforested and agricultural water samples.