Integrated River Management of the East River

Hydrological Modelling of the East River Basin

A physically-based distributed model, MIKE-SHE, is employed to study the spatial and temporal variation of streamflow from 1969-1974; the model is calibrated against 11 hydrological stations in the East River Basin. The model prediction is judged to be sensitive to about ten model parameters, including bedrock depth, hydraulic conductivity and channel roughness. Model parameters are determined through reported physical properties, or model calibration against observed streamflow data, when the field characteristics are unknown.

Prediction for a Small Catchment in Hong Kong

MIKE-SHE is first applied in Siu Lek Yuen, a small catchment in Hong Kong. Siu Lek Yuen has a drainage area of about 2 square kilometer, it serves as a good example for MIKE-SHE model verification, because this catchment has considerably complete streamflow data.

MIKE-SHE is used to predict streamflow in Siu Lek Yuen during 2001 and 2002. Overall, the MIKE-SHE model predicted streamflow meets well with the observation, both the magnitude and timing of peak flows can be captured satisfactorily; the averaged percentage bias between predicted and observed streamflow is within 1%.

Prediction for the East River

The predicted daily-averaged streamflow agrees well with data in mainstream stations, Lingxia and Boluo, during both calibration and validation period. Both peak flows and base flows are satisfactorily predicted in these two stations. However, the flow prediction at a station immediately below a reservoir, e.g. Heyuan (downstream of Xinfengjiang and Fengshuba Reservoirs) is less satisfactory, and is believed to be related to reservoir operation. The effect of the reservoir operations diminishes with distance downstream, and is not notable in Lingxia and Boluo. Overall, good water balance is achieved in most mainstream stations, with a percentage bias within 10%.

calibration period (1969-1973)

validation period (1974-1978)

Predicted streamflow at mainstream stations using MIKE-SHE, calibration (top) and validation (bottom) periods

Upon the completion of hydrological simulation on the East River Basin, water quality modelling can be performed to assess the waste assimilative capacity along the mainstream of the East River.

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