EVALUATION UPON THE USE OF CURVE NUMBER IN RESPONSE OF VARIOUS WATERSHEDS TO RAINFALL IN INDONESIA

• Main Author: Mellivera, Avis
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/70226
• Institution: Institut Teknologi Bandung

Hydrological cycle in a watershed is strongly influenced by surface runoff that occurs in the area where the rain falls. Rainfall with the same duration and intensity will produce different amount of runoff if it falls on areas with different land cover or soil types. One of the most used methods to estimate the amount of direct runoff is SCS CN. But, the Curve Number used in calculations in Indonesia is still not aligned with the land cover class listed on SNI 7645:2014. So, further analysis is needed to determine the Curve Number (CN) value for land cover in Indonesia. Rainfall-Runoff modelling was conducted using ArcSWAT on 3 different wathersheds, majalaya sub watershed with 2006, 2011, and 2013 land cover data, belawan watershed with 2011 and 2013 land cover data, and kali madiun sub watershed with 2011 and 2013 land cover data. Other datas that are needed for the modelling is DEM, soil type, rainfall, climate, and discharge data for calibration purpose. The calibration process is carried out with SWATCUP. From the calibration process for each watershed, a correction factor for curve number value was obtained. The Curve Number value for secondary dryland forest, shrubs, residential, open land, water, dryland agriculture, and paddy fields for hydrologic soil group C respectively are 47.05-50.17, 50.90-54.29, 46.40-49.50, 50.91-54.29, 92, 53.49-57.04, 52.20-55.66. this value is considered not satisfactory because the expected CN range for hydrologic soil group C is generally above 70. Therefore, it is necessary to conduct further research using more modelling samples with a better accuracy level of soil and rainfall data.