Analisis Koefisien Kekasaran Manning Dasar Sungai Kreung Peusangan Pasca Banjir Tahun 2017

Sari

Sungai Krueng Peusangan is very important for the people of Aceh in general and the people of Kabupaten Bireun, in particular development of water resources in the form of raw water, water for irrigation and river tourism areas. At the end of
February Foodway accident on February 2017, a big flood the twisting of the bridge pillar at its headline is the Kuta Blang bridge and finally the bridge was demolished and replace by a new bridge, whice time has been completed and can passed since the end of February 2018. This study to analyze the changes in base sediment since 2004 until flooding in the end February 2017. Riverbed sediment are measured directly in the field and analyzed in laboratorium, are used to calculate the Manning roughness coefficient. Manning roughness coefficient calculation is based on the stricle, Menyer-Peter Muller, KKeulegan and Bray method. The results showed the diameter of base sediment was getting more rough, for 0,35 mm ≤ d50 ≤0,85 mm in 2004 to be 0,85mm ≤d50≤1,80 mm in 2018, Manning roughness coefficient increased. Manning roughness figures is 0,031≤n≤0,038 for condition 2004, and 0,036≤n≤0,047 for condition 2018. Flow downstream of the rubber weir increase from critical flow to supercritical. The flow when flood is also drifting wood debris downstream so that it can erode the cliffs and damage the bridge pillars.