The Calibration Of Discharge Model As An Impact Of Land Use And Climate Changed In Kodina Watershed, The South Of Lake Poso
Changes in land use and climate changed had a direct impact to the flow characteristics and the availability of
water in a watershed. In terms of utilization of water resources of a river or surface water, the design will be based on
historical data (time history) debits. By knowing the river discharge data in the time period, it can be foreseen the magnitude
of the discharge at the future. The mistakes which implied in data of rain and discharge, parameter yielded become less
optimum of the models. Therefore it was required a phase calibrate to evaluate the model. Data of rain, climatology and
discharge in Kodina River were enough to run the models. From two methods were applied in the calculation, It was shows
the Nreca models are more similar with observed data. Therefore the calibration model was only tested the Nreca Models.
The result of the calibration models shows the errors is 4.81%, coefficient correlation is 0.736, Initial SMS is 200 mm, and
Nominal is 835.8 mm. After running the Nreca model, the it was calibrated and validated concerning to land use changed the
model are tested again. The result of calibration shown, the maximum discharge is 33.33 m3/s while the observed data is
32.96 m3/s. The minimum debit is 2.55 m3/s and observed discharge is 3.29 m3/s. The average of discharge for the model is
6.12 m3/s while the observed data is 15.58 m3/s.
Rainfall and discharge model of hydrology stream used Nreca method, with three especial parameter. Result calibrate to
indicate that value of parameter to: make an index to soil moisture storage capacity (Nominal) = 835.8 mm ; PSUB = 0,91 ;
Percentage of the pool of groundwater flowing into the river as the base flow (GWF) = 0.18. While correlation coefficient
value (r) = 73.59 %, and number of error is 4.81. The results shows the relation of observed discharge and the model result
are very close. Assess the parameter serve the purpose of assess characteristic of catchment area having an effect on to
occurence of stream in DAS Kodina.
Keywords— Land use, Evapotranspitation, Nreca Model and Calibrations, Discharge.