Study Area 3: <u>Site 5 Water flow velocity of Sidr (2007): 0.618m/s Site 6 Water flow velocity of Sidr (2007): 0.987m/s Site 7 Water flow velocity of Sidr (2007): 0.709m/s</u>

|**Site 5**|**Site 6**|**Site 7**||
|---|---|---|---|
|**67%**|**68%**|**78%**|**50 m width of****_Sonneratia apetala_ at 5m spacing followed by**<br>**50 m width of****_Avicennia officinalis_ at 4m spacing and**<br>**2000 m width of****_Ceriops decandra_ at 5m spacing**|
|**65%**|**66%**|**69%**|**50 m width of****_Sonneratia apetala_ at 5m spacing followed by**<br>**50 m width of****_Avicennia officinalis_ at 4m spacing and**<br>**1000 m width of****_Ceriops decandra_ at 5m spacing**|
|**63%**|**63%**|**60%**|**50 m width of****_Sonneratia apetala_ at 5m spacing followed by**<br>**50 m width of****_Avicennia officinalis_ at 4m spacing and**<br>**500 m width of****_Ceriops decandra_ at 5m spacing**|
|**61%**|**60%**|**56%**|**50 m width of****_Sonneratia apetala_ at 5m spacing followed by**<br>**50 m width of****_Avicennia officinalis_ at 4m spacing and**<br>**100 m width of****_Ceriops decandra_ at 5m spacing**|
|**61%**|**60%**|**56%**|**50 m width of****_Sonneratia apetala_ at 5m spacing followed by**<br>**50 m width of****_Avicennia officinalis_ at 4m spacing and**<br>**100 m width of****_Excoecaria agallocha_ at 5m spacing**|
|**62%**|**61%**|**57%**|**50 m width of****_Sonneratia apetala_ at 5m spacing followed by**<br>**50 m width of****_Avicennia officinalis_ at 4m spacing and**<br>**100 m width of****_Heritiera fomes_ at 5m spacing**|
|**57%**|**59%**|**54%**|**50 m width of****_Sonneratia apetala_ at 7.5m spacing followed by**<br>**50 m width of****_Avicennia officinalis_ at 6m spacing**|
|**57%**|**59%**|**54%**|**50 m width of****_Sonneratia apetala_ at 7.5m spacing followed by**<br>**50 m width of****_Avicennia officinalis_ at 4m spacing**|
|**57%**|**59%**|**54%**|**50 m width of****_Sonneratia apetala_ at 5m spacing followed by**<br>**50 m width of****_Avicennia officinalis_ at 6m spacing**|
|**59%**|**59%**|**56%**|**50 m width of****_Sonneratia apetala_ at 5m spacing followed by**<br>**50 m width of****_Avicennia officinalis_ at 4m spacing**|
|**53%**|**55%**|**51%**|**50 m width of****_Avicennia officinalis_at 6 m spacing**|
|**55%**|**58%**|**53%**|**50 m width of****_Avicennia officinalis_ at 4m spacing**|
|**53%**|**55%**|**51%**|**50 m width of****_Sonneratia apetala_ at 7.5 m spacing**|
|**57%**|**59%**|**54%**|**50 m width of****_Sonneratia apetala_ at 5m spacing**|

Our estimates confirm the protective role of mangroves during cyclones and highlight that the extent of attenuation of surge height and surge flow velocity from mangroves is locationspecific and depends on mangrove species, width of mangrove area as well as the density of planting. Among the three study areas considered in our analysis, attenuation of surge height is relatively higher in study area 3, which is sea-facing and shallower compared to the other study areas on river banks.<sup>17</sup> Among the seven sites considered in our analysis, the reduction of surge

> 17 The variation in bed level of study area 1, study area 2 and study area 3 are from -6mPWD to -10mPWD,

> -10mPWD to -12mPWD and 0mPWD to -3mPWD respectively (Reference: Figure A1 in the appendix).

22