6,8-Dichloro-N-methyl-3-nitro-4-nitro­methyl-4H-chromen-2-amine

In the title compound, C11H9Cl2N3O5, the dihydro­pyran ring adopts a near-half-chair conformation. The benzene ring makes a torsion angle of 5.02 (5)° with the dihydro­pyran ring. Adjacent mol­ecules are inter­linked through inter­molecular C—H⋯O, N—H⋯O and C—Cl⋯π [3.4743 (9) Å] inter­actions. The inter­molecular N—H⋯O hydrogen bond generates an R 2 2(12) motif, which is observed to contribute to the crystal packing stability. Moreover, the mol­ecular structure displays an S(6) motif formed by intra­molecular N—H⋯O hydrogen bonding

6-Meth­oxy-N-methyl-3-nitro-4-nitro­methyl-4H-chromen-2-amine

In the title compound, C12H13N3O6, the dihydro­pyran ring adopts a near screw-boat conformation. The dihedral angle between the mean planes of the benzene and dihydro­pyran rings is 6.35 (5)°. An intra­molecular N—H⋯O hydrogen bond generates an S(6) motif, which stabilizes the mol­ecular conformation. In the crystal, weak inter­molecular C—H⋯O, N—H⋯O and C—H⋯π hydrogen bonds contribute to the stabilization of the packing

4-[4-(Diethyl­amino)­phen­yl]-N-methyl-3-nitro-4H-chromen-2-amine

In the title compound, C20H23N3O3, the dihydro­pyran ring adopts half-chair conformation. The chromene system makes a dihedral angle of 87.35 (5)° with the adjacent benzene ring. An intra­molecular N—H⋯O hydrogen bond generates an S(6) motif, which stabilizes the mol­ecular conformation. In the crystal, weak inter­molecular C—H⋯O hydrogen bonds contribute to the stabilization of the packing

A numerical study of hypothetical storm surge and coastal inundation for AILA cyclone in the Bay of Bengal

The head Bay region bordering the Bay of Bengal is highly vulnerable to tropical cyclones. Catastrophic risks from storm surge and associated inundation are quite high due to high population density in coastal areas, socio-economic conditions, and shallow bathymetry. It features the world’s largest deltaic system comprising of ‘Sunderbans’ bordered by West Bengal and Bangladesh. In a geomorphologic sense, the head Bay region is a low-lying belt comprising several barrier islands and river drainage systems, numerous tidal creeks, and mud flats having a high risk for widespread inundation. In addition, the high tidal range together with low-lying topography leads to high risk and vulnerability from storm surge inundation. During May 2009, a severe cyclonic storm Aila struck West Bengal causing enormous destruction to life and property along coastal belts of West Bengal and Bangladesh. It was the strongest pre-monsoon cyclone in the past two decades that had landfall in West Bengal. This work reports on a numerical study for hypothetical storm surge and associated inundation from Aila using the ADCIRC model. The study covers a comprehensive qualitative analysis on water level elevation and onshore inundation for West Bengal and Bangladesh regions. The estimated peak storm surge was about 4 m in the Sunderban region that propagated into all major riverine systems, inundating the river banks as well the inland areas. Numerical simulations indicate an average inland penetration distance of 350 m with a maximum of 600 m at various coastal locations in West Bengal and Bangladesh. The study emphasizes the need and importance of inundation modeling system required for emergency preparedness and disaster managemen

A numerical study of coastal inundation and its validation for Thane cyclone in the Bay of Bengal

The numerical modeling of coastal inundation from severe cyclones is a challenging area for coastal hazard mapping, emergency planning and evacuation measures. There is a need for realistic estimate of onshore coastal inundation by the operational weather centers for precise warnings to minimize loss of life and property. At present, there is no modeling effort to evaluate the extent of coastal inundation for any coastal state in India. The operational center disseminates information only on peak surge and its location just before cyclone landfall, with no prior information about onshore inundation. To bridge this gap, the present study applies the state-of-art ADCIRC hydrodynamic model to evaluate peak surge and onshore inundation along coastal Tamil Nadu for the December 2011 Thane cyclone event. Post-storm analysis and field reconnaissance survey report from IMD and ICMAM were available for the Thane cyclone to skill assess model computation. The model that computed peak surge and onshore inundation is in good concurrence with field measurements. The study signifies that near-shore beach slope has a direct bearing on onshore inundation, and its importance in numerical modeling is highlighted. This study being first of its kind for Indian coast, emphasized that coastal inundation modeling should form an integral part in a storm surge prediction system for operational needs