While the systems constructed by the Romans were gainfully re-used over the ages, the contribution of Islamic civilisation in water management is also important. The large-scale Arab immigration and population increase led to the growth of a new landholding class who invested in agricultural production. Thus, the heritage of Roman techniques in water management was further developed under the Islamic dynasties, as can be seen by the construction of many water-management systems, including subterranean canals, regular canals, aqueducts, cisterns, dams, rain reservoirs and waterwheels (noria).