There are different ways in which the hazard can be predicted, namely, time-independent and time-dependent predictions (the latter are also referred to as forecasts). The time-independent predictions give information on areas prone to hazard, their expected intensities and recurrence times.
For example, seismic hazards are predicted in the following way: statistical calculations make it possible to assess the probability of occurrence (or non-occurrence) of a hazardous event of a given intensity at a given place in a given time interval: the operating basis earthquake (OBE) with a recurrence interval of 237 years should be taken into account, i.e. the structure must be able to safely withstand such earthquake without damage. The risk of flood hazard for a dam can be predicted in a similar way where the Inflow Design Flood (IDF) is used to design and/or modify a specific dam, particularly when deciding on the dimensions of the spillway and outlet works. All these assessments improve dam resistance to extreme events.
Unfortunately, it is still impossible to reliably forecast the time at which an earthquake will occur. It is easier to predict flooding, as the monitoring of meteorological parameters (including data on precipitation, temperature, and snow cover) makes it possible to calculate the volume of discharged water. Then the specific outlet works can regulate the floodwater outflow.
Landslide hazards also can be monitored by modern technology (Global Positioning System or GPS, Light Detection and Ranging Systems or LIDARS, Inverse Synthetic Aperture Radar or INSAR), which indicates the level of displacement of surface points; regular monitoring of the velocity of mass-movement gives a sound basis for predicting critical state, which can be caused, among other things, by heavy rain and intensive melting of snow cover.
Similar to seismic zoning, “flood zoning” (the plotting of inundation maps) is very useful in predicting the extent of potential flooding, the height of water and the time of front wave arrival. It is possible to calculate the time-space flood scenario more precisely, using detailed digital elevation maps.