Flooded houses are seen following heavy rain in a neighbourhood in the northern Gaza Strip February 16, 2017. REUTERS/Mohammed Salem - RTSYYKF

A Palestinian walks through flood water following heavy rain in a neighbourhood in the northern Gaza Strip February 16, 2017. REUTERS/Mohammed Salem - RTSYYR8

A Palestinian girl walks outside her family house following heavy rain in a neighbourhood in the northern Gaza Strip February 16, 2017. REUTERS/Mohammed Salem TPX IMAGES OF THE DAY - RTSYYRH

A Palestinian woman inspects her shelter that was flooded during a rainstorm, in the northern Gaza Strip February 17, 2017. REUTERS/Mohammed Salem TPX IMAGES OF THE DAY - RTSZ4OO

A Palestinian man inspects his shelter that was flooded during a rainstorm, in the northern Gaza Strip February 17, 2017. REUTERS/Mohammed Salem - RTSZ4RB

A Palestinian man evacuates his children after his house was flooded with rainwater in Rafah in the southern Gaza Strip, February 15, 2017. REUTERS/Ibraheem Abu Mustafa TPX IMAGES OF THE DAY - RTSYRNX

A Palestinian walks through flood water following heavy rain in a neighbourhood in the northern Gaza Strip February 16, 2017. REUTERS/Mohammed Salem - RTSYYRC

A Palestinian woman asks for help after her house was flooded following heavy rain in a neighbourhood in the northern Gaza Strip February 16, 2017. REUTERS/Mohammed Salem - RTSYYRG

A Palestinian woman inspects her shelter that was flooded during a rainstorm, in the northern Gaza Strip February 17, 2017. REUTERS/Mohammed Salem - RTSZ4PF

Palestinian children look at a shelter that was flooded during a rainstorm, in the northern Gaza Strip February 17, 2017. REUTERS/Mohammed Salem - RTSZ4RE

Palestinians inspect a flooded house following heavy rain in a neighbourhood in the northern Gaza Strip February 16, 2017. REUTERS/Mohammed Salem - RTSYYRD

A Palestinian walks through flood water following heavy rain in a neighbourhood in the northern Gaza Strip February 16, 2017. REUTERS/Mohammed Salem - RTSZ0A0

A Palestinian boy removes rainwater from his flooded house in Rafah in the southern Gaza Strip, February 15, 2017. REUTERS/Ibraheem Abu Mustafa - RTSYRNY

Palestinian boys take cover in the remains of a vehicle during heavy rain in a neighbourhood in the northern Gaza Strip February 16, 2017. REUTERS/Mohammed Salem - RTSYYRZ

A Palestinian girl is seen through a hole in a wall as she wades through floodwaters following a rainstorm, in the northern Gaza Strip February 17, 2017. REUTERS/Mohammed Salem - RTSZ4PZ