Characterization and Estimation of Low Flows in the East River (Dongjiang) Basin

Principal Investigator:
Chen, Yongqin

Co-investigator(s):
: ---

Summary:
Water resources in the East River basin have been highly developed and heavily committed for a variety of uses such as water supply, hydropower, navigation, irrigation, and suppression of seawater invasion. In recent years, the East River provides supply to meet about 80% of Hong Kong's annual water demands. Compared to flood problems and their associated hazards, which are often more visible and dramatic, fewer efforts have been devoted to study the occurrence, characteristics, estimation techniques and environmental and economic impacts of river low flows. However, low-flow conditions and hydrologic droughts are obviously very crucial to the reliability and vulnerability of the East River water resources systems to satisfy the multiple objectives of water uses. This study is therefore proposed to employ hydrologic analysis methods for low-flow characterization and estimation. The objectives of this research are two-fold :

(1) to characterize the temporal and spatial patterns of low flows using frequency analysis and baseflow recession analysis techniques; and

(2) to develop regionalized estimates of low-flow statistics for ungauged river sites using watershed and climatic parameters.

Two techniques, frequency analysis and baseflow recession analysis, will be performed to characterize low flows in terms of minimum average-streamflow rates and the associated probability distributions. To estimate low-flow statistics at ungauged sites, this study will adopt a regional hydrologic modeling approach to developing statistical relationships between low-flow statistics at gauged sites and a number of drainage basin characteristics derived from maps and remote sensing images. This study will not only have tremendous scientific merits, but also highly valuable practical significance and enormous relevance to Hong Kong.