According to Lee, landslides require three fundamental conditions: a mass of earth, a large amount of rainfall, and a sufficiently steep slope in a riverbed (at least 15-30o). Geology, hydrological factors, and soil density also play a role. Given the complexity of the factors that give rise to landslides, he feels that it is unfair to simply attribute them to betel-nut cultivation.
他表示，要形成土石流至少有 3 個基本要件，一是有大量土石，第二需要高降雨量，第三要在一定的溪床坡度（15-30 度）以上，此外還包括地質、水文條件、土石密度等，誘發因子複雜，只歸因於檳榔有欠公允。