Study on Temporal Variability of Hydrological Elements in the Daqing River Basin, China

Abstract

To reveal the temporal variability of hydrological elements in the Daqing River Basin (TDRB), an index system with temporal variability indices of hydrological elements, namely jump variability, trend variability, and period variability, is constructed. These indices are calculated with the help of variability diagnosis methods. Additionally, the entropy weight method and technique for order preference by similarity to an ideal solution (TOPSIS) evaluation model are combined to grade and evaluate the temporal variability of hydrological elements. The results show that (1) there is no temporal variability in rainfall, but runoff shows jump variability in 1979 with a sharp decrease. Meanwhile, groundwater depth presents jump variability in 1998 with a significant increase. (2) The period variabilities of runoff and groundwater depth are mainly exhibited in the medium-long periods. After the variability, the decomposed component periods become shortened in runoff while longer in groundwater depth. Furthermore, there is a significant change in the entropy of the medium-long periodic components, indicating higher variability in these components. (3) The importance of temporal variability indices of runoff and groundwater depth is that jump variability is the largest, followed by trend variability, and period variability is the least. The variability significance plays a paramount role in jump variability and trend variability, whereas in period variability, the entropy after variability should be focused. The comprehensive evaluation scores of the runoff and groundwater depth showing medium-strong temporal variability are 0.645 and 0.678, respectively. This study provides a new approach for studying the temporal variability of hydrometeorological elements in other meteorologically similar regions.