Overview

The need for optimal land use strategies has never been greater than at present, considering land degradation statistics and increased population pressure

on limited resources. The adoption of intensive land use for agriculture coupled with deforestation have resulted in high soil erosion rates and degradation of land and water resources throughout the tropics, especially in sloping lands where upstream springs are drying up and land productivity is either declining or has already been lost. This degradation leads to heavy siltation of downstream reservoirs and irrigation canals, seasonal flooding, and a decline in quantity and quality of irrigation water, thus affecting productivity of the lowlands. The Manupali River Watershed, which drains into Pulangi River and covers an area of approximately 60,000 ha, is typical ofsuch a situation. The upper area still has some forest cover, while the lower stretches are cultivated. More than 40 percent of the watershed is hilly with slopes of40 percent. Migration of people into the area from Luzon and Visayas has led to a rapid population increase (approximately 11 percent annually between 1970 and 1992 in the municipality of Lantapan), resulting in further deforestation and increased agricultural activities in cleared areas. The need to understand soil and water resource use at the watershed level is critical in

order to recommend sustainable farming practices and to extrapolate the methodology and results to other threatened regions.