Evaluating the post-earthquake landslides sediment supply capacity for debris flows

•A novel dimensionless index (MLSDR) was proposed to efficiently assess the post-earthquake landslides sediment supply capacity (SSC) for debris flows.•The 1 km2 threshold between hillslopes and channels in Wenchuan Earhquake-affected area is distinguished using logarithmic slope–area diagram.•Catchments with higher active debris flow in Wenchuan Earhquake-affected area are identified based on the values of 0.2 ≤ MLSDRout ≤ 2.25 and 0.3 ≤ MLSDRchannel ≤ 4.5.•Short- and long-term changes in post- Wenchuan earthquake SSC are dominated by the strong earthquakes and precipitation, respectively.