LTS instantaneous events

An instantaneous LTS event is a local maximum in time of a certain quantity, typically water level or discharge. The LTS module registers only instantaneous events which are found to be independent, i.e. they must fulfill simultaneously the following two criteria:

1. Interevent time criterion DT: two successive instantaneous events are independent if the time difference between the two events exceeds DT. In other words, a local maximum in a time series is an event maximum if there are no larger local maxima within ±DT of the local maximum.

2. Interevent level criterion p (0<p<1): two successive instantaneous events are independent if the smallest level between the two events becomes smaller than p times the value of the smallest of the two events.

Please note that in some cases criterion 2 needs to be applied with respect to a common zero level for the quantity. For example, for a water level in a node, the zero level would correspond to the node bottom level. In general, to identify events for water levels, the criterion 2 is applied to water depths.

Examples

shows several examples of LTS event identification, using the two criteria.

Figure: Examples of LTS event identification.