H. Pawitan
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MODIFICATION OF C-USLE FACTOR IN ANSWERS MODEL TO PREDICT SOIL EROSION IN HUMID TROPICAL REGION (CASE STUDY OF NOPU UPPER CATCHMENT, CENTRAL SULAWESI) HIDAYAT, Y.; SINUKABAN, N.; PAWITAN, H.; MURTILAKSONO, K.
Jurnal Tanah dan Iklim (Indonesian Soil and Climate Journal) No 32 (2010): Desember 2010
Publisher : Balai Besar Penelitian dan Pengembangan Sumberdaya Lahan Pertanian

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.21082/jti.v0n32.2010.%p

Abstract

The research was carried out: a) to define crop and management factors as input parameter of ANSWERS model, b) to establish an ANSWERS to PCRaster model to simulate land use changes and soil and water conservation techniques, and c) to study the impact of rainforest conversion towards surface runoff, soil erosion and nutrients losses. Surface runoff and soil erosion were measured daily on primary forest, secondary forest, open areas, maize, peanut, young cocoa, medium cocoa, old cocoa, and intercropping between young cacao, maize, banana, and cassavas. In watershed outlet, surface runoff and sediment discharges were determined through measurement of water height, velocities and sediment sampling. Using a partial crop and management factors, the original and PCRaster type of an ANSWERS model performs better in predicting soil erosion thanUSLE crop and management factors especially for high rainfall events. Reforestration of very steep land (slope > 45%) which followed by application of ridge terraces on agricultural areas were the best management practices to control surface runoff and soil erosion to ensure sustainable agriculture andsustainability of watershed functions. Rainforest conversion to agricultural areas increases surface runoff, soil erosion andnutrients losses.
INTERSEPSI HUJAN DAN PENGARUHNYA TERHADAP PEMINDAHAN ENERGI DAN MASSA PADA HUTAN TROPIKA BASAH ” STUDI KASUS TAMAN NASIONAL LORE LINDU” Abdul Rauf; H. Pawitan; T. June; C. Kusmana; G. Gravenhorst
Agroland: Jurnal Ilmu-ilmu Pertanian Vol 15, No 3 (2008)
Publisher : Universitas Tadulako

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (230.262 KB)

Abstract

The field observation of this research was conducted from June 2005 – May 2007 in tropical rainforest at Lore Lindu National Park Central Sulawesi. The main objectives of this research  were to study  (i) the relationships between interception loss and rainfall properties and vegetation characters and to determine the dominant factors affected (ii) the effect of  rainfall interception on energy flux and mass transfer and  (iii) the dynamics of vertical energy flux under the forest and grass land. Rainfall interception was  36.34 % of gross rainfall in 200 events, Depth rainfall and LAI factors had strong effects on rainfall interception. The relationships could be expressed  as  Ic = 0.980+0.239P+0.035LAI  (R2 = 0.78).  The output of this equation was compared with Gash model and the observation value showed that deviation of the equation was  1 % and less than Gash model, so that equation gave as good result as Gash model gave. By considering the data requirements and calculation procedures it was concluded that this equation is applicable for interception prediction. Land use type had effects on  radiative and energy balance. Net radiation (Rn) in the forest was 10.66 MJ/m2/day and higher than  in the  grass land where incident global radiation was similar. Vertical latent heat flux in the forest was 9.53 MJ/m2/day or 89.40% Rn in rainy day and  8.41 MJ/m2/day or 74.56 % Rn in   dry day, on the other hand,  in the grass land, sensible heat flux was higher  than latent heat flux of all weather condition.  Direct effect of rainfall interception on energy flux  and mass transfer might be described that is needed latent heat 9.0 MJ/m2/rainy day to evaporate the rain intercepted of 3.69 mm/rainy day. Effect of rainfall interception had positive correlation with  latent heat flux and the negative correlation  with sensible heat flux.