Real world properties (physical, chemical, biological, water level, conductivity)<br /></p><p><br /></p><p>May be real observation or simulation.<br /></p><p><br /></p><p>Use of sampling features.<br /></p><p><br /></p><p>Continuous or discrete measurements.<br /></p><p><br /></p><p>Use of specimens/samples - may be analysed offsite at a laboratory.<br /></p><p><br /></p><p>Often related to particular programs, management units or administrative organisations.<br /></p><p><br /></p><p>Hydro features often cross political or administrative boundaries (countries, states, management areas).<br /></p><p><br /></p><p>Data often continuously monitored but aggregated as hourly, or daily data.<br /></p><p><br /></p><p><br /></p>