The system should be updated continuously (temporally and spatially), easily updated, consulted and integrated with other sensitive data – such as soil use, plant cover, hydrometrics, levels of surface invasions and underground phenomena, etc. – which derive from measurements, estimation or models and are present in the structure or readily available from other entities/institutions.
Wilhite, D.A., 2000. “Drought as a natural hazard: concepts and definitions” in Drought: A Global Assessment, Volume I, D. A. Wilhite (ed.). Routledge, London, pp. 3-18 [pdf document]
You can find further information, suggestions and some data on the importance of water at the following link: http://www.lamma.rete.toscana.it/risorsa-idrica