Iman Yani Harahap dan M. Edwin Syahputra Lubis
ASSESSMENT MODEL MUKA AIR TANAH PADA PERTANAMAN KELAPA SAWIT DI LAHAN BERBUKIT
ASSESMENT OF WATER TABLE MODEL ON OIL PALM AREA IN A HILLY LANDyang relatif tinggi pada puncak bukit diduga mereduksi air infiltrasi sehingga mengurangi inflow air. Sedangkan pada area lereng dan kaki bukit, inflow air dari area puncak yang berasal dari run-off, meningkatkan air infiltrasi pada kedua area tersebut, sehingga pengukuran aktual lebih tinggi dari keluaran model. Penyesuaian parameter laju run-off dan gradien potensi hidrolik pada area lereng dan perbukitan dapat meningkatkan akurasi keluaran model. Kata kunci : kelapa sawit, model muka air tanah, sumur pantau, kelerengan, puncak bukit, kaki bukit, gradien potensial hidrolik Abstract The aim of this research is to assess performance of developed water table model on oil palm area in a hilly land. The model requires some data of initiatial condition, input model, and physical parameters of the soils and crops. Initial data includes leaf area index, latitude geography position, initial water table, and the deep of impermeable soil layer. Input model includes daily weather data (rainfall, temperature, solar radiation, and wind speed). Soil physic parameters includes bulk volum density at each soil layers, and run-off of the soil surface. The crop parameters includes rainfall interception of crown and stem plants. Daily water table measurement was carried out at 3 points of wells located in one line hilly catena (30 -70 m above sea level) with slope about of 15% (top, middle, and foot). The area was the 20 years old oil palm planting area, soil type was Typic Hapludult with coarse to fine soil texture, hydraulic conductivity was classified as fast. The water table in this area was located in unconfined aquifer zone. The results showed that outputs of the model were 3 -4% higher than the * *