EVOLUTION OF JOINT DEPENDENCE OF DAILY AVERAGED WATER LEVELS AND DYNAMIC BOUNDARIES IN ZHUJIANG(PEARL)RIVER CHANNEL NETWORKS
The daily averaged water levels of the Zhujiang(Pearl)River channel networks are mainly driven by the dynamic and morphological boundaries.However,due to the abrupt variation of the morphological boundary owing to the intensive human interventions,together with the influence of dynamic boundary changes(the river discharge and sea level outside the estuary),the daily averaged water level pattern of the channel networks altered considerably.The evolution of Copula joint dependence of daily averaged water levels and dynamic boundaries in Zhujiang River channel networks were studied for risking assessment of extreme daily averaged water level,which is essential concerning the sustainable water resources managements in estuaries.Results show that the variation of joint dependence of daily averaged water levels and dynamic boundaries presented an obvious change,which is characterized by the decline of daily averaged water level with the same probability in the upper reaches of the river channel networks driven by the same river discharge or sea level,the decline of high water level with the same probability in the middle and lower reaches and the rise of low water level,and the rise of daily averaged water level with the same probability in the estuary mouth.The risk assessment of extreme daily averaged water level before and after intensive human interventions shows that,for given the encounter probability of river discharge and sea level ranging from 10％to 90％in the middle and upper reaches of the river channel networks,the daily averaged water levels would be decreased ranging from 0.02 to 1.24 m;for given the encounter probability of 90％in the middle and lower reaches,the variation is consistent with those in the upper reaches but the range of the decrease could be reduced ranging from 0.05 to 0.23 m.However,for given the encounter probability of 10％in the same reaches,the daily averaged water levels would be increased ranging from 0.01 to 0.07 m;for given the encounter probability of river discharge and sea level ranging from 10％to 90％in the estuary mouth,the daily averaged water levels be increased ranging from 0.02 to 0.09 m.In summary,following intensive human interventions,the influence of dynamic boundaries on the channel networks'water levels has significantly weakened,leading to a reduced overall resilience of daily averaged water levels and an increased risk of extreme water level events.
daily averaged water levelriver dischargesea levelintensive human interventionsCopula joint probability distribution
万方数据
维普
