Suprizingly, being in the tropics does not make water any less
important. Average person doing strenous exercise requires some 6-8
litres of water (compared to 4 litres for other activities) per
person per day!
Maybe in Iraq they don't even have brackish water to 'reverse
osmosis' and make Odivia Lum even richer; but access to water may
be a nightmare in mordern war as combat elements are seldom static
etc.
"An army marches on its stomach" is even true nowadays.
Only army to achieve more than 12 miles/day strategic advance are
the mongol hordes. Mordern army may move far but take longer and
have lower guns to butter ratios.