Detecting the Abrupt Change in Hydrological Time Series: A Methodological Review

Hydrological time series particularly the discharge data series carries the signature of the change in basin hydrological phenomena that may occur abruptly or gradually or in more complex manner. Many statistical tests are available for capturing such temporal behaviour of the hydrologic processes but still the task is quite challenging since much care needs to be taken regarding variable selection, data pre-processing and choosing right statistical tests depending upon the nature of the data, geographical condition of the basin, purpose of the study etc. Very often more than one method of change detection is required to be applied and ultimate decision making becomes subjective depending on the geographical condition of the basin. So, one needs to be very cautious about the applicability of the available tests when these are being applied. Here, an attempt has been made to review the assumption and applicability of available statistical tests which are solely designed for detecting step change in hydrological time series.