Some examples of the basin entropy analysis by TANK model

The BASIN ENTROPY, ENT, was proposed as a new index indicating the basin characteristics by Shiotsuki. ENT is written by the equation (6) in this paper. The meaning of each letter for unit time duration is as follows

2S=ENT, Q1=Surface Inflow into basin at altitude T1,Q2=Surface Outflow from basin at T2,R=Rainfall at TR, E=Evaporation at TR, Δ W=Basin Storage Change, G=Infiltration downward at T2. The first term of the right hand of (6) is the FLOW ENTROPY which is always negative because of T1>T2. The second is the net RAIN ENTROPY, also always negative by T1>TR>T2. The third term is the STORAGE ENTROPY, positive when Δ W>0 or negative when Δ W. ΔW>0 means the increase of the basin water resources and Δ W<0 means those decrease. The total entropy ENT indicates the basin is rich in the water resouces when ENT>0. On the other hand the basin takes on the different character, disastrous, when ENT<0. The basin entropy analysis are made for the various basins with the different scales in this paper. It is found that the effect of the man made DAM can be assesed or evaluated by the basin entropy analysis.