The influence of climate and man on the watercourses of Malta. 1989. Toxicological and Environmental Chemistry, 2021, 8592.
In Malta, rain (averaging c. 500 mm per year) falls mainly in autumn and winter, replenishing the land dried in the hot and rainless summer. Man's influence is necessarily exercised within these limits but, given that, is of almost equal ecological importance. Water regime is controlled not only by precipitation and run-off, but also by the frequency of dams, abstraction (and date of last emptying in spring), and diversion of groundwater before it reaches the rivers. Habitats are disturbed not only by storm flows, but also by farming, communication and other management, and are also influenced by land use.
River pollution is less than in equivalent parts of Mediterranean France and Italy, mainly because older settlements are on the perennial groundwater supplies rather than on the more ephemeral streams. In consequence, streams are not traditionally used for rubbish disposal. Also, water is scarce and needed for irrigation, so gross pollution is unacceptable.
The aquatic vegetation varies with the duration, depth and movement of surface water, summary soil moisture, disturbance and pollution.