Long-term streamflow data are essential for water resources planning and management, cascade reservoir scheduling, and understanding the response of water resources to climate change and human activities. Streamflow reconstructions can effectively “fill-in” missing runoff data gaps. However, considering the scarcity of observational monitoring stations and the limitations of distributed hydrological models, the reconstruction of long-term time series of runoff under varying surface and climatic conditions remains a challenge. Here, we propose a hydrological knowledge-informed Long Short-Term Memory (LSTM) model (Hydro-LSTM) for monthly streamflow reconstruction using open-access distributed data. Hydrological knowledge was derived from hydrological governing equations and parameters for each independent water cycle component. The Hydro-LSTM addresses the lack of physical consistency inherent in data-driven models, along with missing observations. The approach was applied to simulate monthly runoff of representative rivers in the Tibetan Plateau (TP) from 1980 to 2018. The results show that streamflow reconstructions for these eight stations yielded favorable levels of performance; trends in dynamic change and the range of runoff in the model training period and test period are consistent with the measured values. Values of NSE, CC, and KGE range between 0.715–0.968, 0.847–0.985, and 0.786–0.969, respectively. The influence of hydrological expertise and distributed data on the model is discussed. The introduction of hydrological knowledge makes the driving elements have hydrological significance, which improves the physical consistency and interpretability of the Hydro-LSTM model. The proposed Hydro-LSTM is expected to (1) achieve accurate and efficient reconstructions of long-term runoff time series using open-access distributed data and limited observations and (2) provide a new perspective for runoff reconstruction and prediction, with promising application prospects.
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