The Muskingum model of routing a flood through a stream reach is expressed as O₂ = K₀I₂ + K₁I₁ + K₂O₁, where K₀, K₁ and K₂ are the routing coefficients for the concerned reach, I₁ and I₂ are the inflows to the reach, and O₁ and O₂ are the outflows from the reach corresponding to time steps 1 and 2 respectively. The sum of K₀, K₁ and K₂ of the model is