Method of Discharge Data Assimilation into the ECOMAG Model Based on the Inverse Stream Routing Approach
摘要
The paper describes and evaluates the effectiveness of a data assimilation algorithm for measured water discharges, implemented for the ECOMAG physical-mathematical semi-distributed hydrological model. The data assimilation algorithm is based on the concept of Inverse Stream Routing (ISR). The Amur River catchment area was chosen as the object of study. To test the assimilation algorithm, daily discharge data from 135 hydrological gages for the period 2008–2020 were used. It was shown that for half of the hydrological gages, the modeling efficiency criterion improved by >50% due to the application of ISR. The limitations of the ISR method are mainly related to the calibration efficiency and the density and quality of runoff observation data. For individual first-order rivers with a catchment area of 1.0–1.5 thous. km2, located in the middle reaches of the Amur, Zeya, and Argun with initially low model efficiency, the application of ISR did not lead to an improvement in the modeling quality estimates above the generally accepted minimum boundaries of satisfactory results. For an area of 100 thousand km2 and more, the effectiveness of ISR application gradually decreases, presumably due to limitations associated with simplifications in the runoff transformation model (kinematic wave) and the assignment of morphometric and hydraulic characteristics based on stream lengths and Strahler system orders. It is concluded that the runoff inversion algorithm conveys a significant amount of information about measured water discharges and allows for a fairly accurate reproduction of runoff hydrographs at control sites with a relatively low computational cost.