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Asian Journal of Agriculture and Development (AJAD) - Call for papers!

Land Use Development Strategies for the Rehabilitation of Gajahmungkur Reservoir Subwatershed

(Indonesia), Doctor of Philosophy in Soil Science (University of the Philippines Los Baños)

Dissertation Abstract:

 

A land use planning study was conducted for Upper Solo, Gajahmungkur Reservoir Watershed in Indonesia to determine the best land use alternative through simulation models to obtain least erosion rate, well-distributed streamflow, increased productivity of crops, and improved farmers' incomes. The Universal Soil Loss Equation (USLE) was used as the basic method for all computations.

It was observed that the ratios of maximum and minimum discharge and runoff coefficients from 1982 to 1993 had no trend. The stream discharge and sediment load before and after 1988 were somewhat erratic. The present erosion rates ranged from 1.0 I to 3,343.40 mt/ha/year in the dif ferent land mapping units. The average was 159.47 mt/ha/year (about 15.95 mm/year), which was significantly higher than the tolerable soil loss (TSL) of 30.03 mt/ha/year (about 3.0 mm/year). The critical soil erosion areas were settlements and home gardens, unpaved roads, ditches, and trails.

Results of the simulation models indicated that land use a lternative 4 yielded the lowest erosion rate (29.61 mtlha/year), well distributed Qmax/Qm in of 16, best choices of land use value rating (L VR) and land manageme nt rating (LMR), and the highest farmers' income. Land use alternative 4 is characterized by high quality bench terraces, conserved settlements, and home gardens. The cropping patterns consist of paddypaddy-soybean for irrigated rice fie lds, paddy-soybean for rain fed rice fields, and peanut-peanut monoculture on terraced upland areas.

Land use alternative 4 was economically feasible and highly profitable. This land use opt ion was not sensitive to increases in production costs or reduction in prices of commodities.

Food demand of the subwatershed could be met by existing land use or land use alternative 4. However, additional income from perennial crops is needed to provide for the other basic living expenses of the farmers.