Among the technologies listed, computer modeling systems for hurricanes typically provide the greatest warning time before the hazard occurs. Hurricane forecasting can give days of advance warning (usually 3 to 7 days) about potential landfalls, allowing for evacuation and preparation measures.
In contrast, seismographs for earthquakes often provide little to no warning (seconds to minutes), while Doppler radar for tornadoes generally provides warnings on the order of minutes to a couple of hours. Water level and rainfall gauges for floods can help in monitoring ongoing situations, but predictive capabilities are often limited compared to hurricane forecasting.
Therefore, when considering warning time before the hazard occurs, computer modeling systems for hurricanes are generally the most effective.