Study On River Ecological Water Equirement Under The Hydrologic Alteration

Currently,the changing environment exacerbated the deterioration of the river ecosystem by hydrologic alteration.In order to enrich the connotation of the theory in ecological water requirement,and provide the basis information for the ecological regulation of Chengbihe Reservoir,this paper studied the river ecological water requirement in Chengbi River under the hydrologic alteration.The main contents and results are as follows:Firstly,IHA/RVA method was used to analyze the impact of hydrologic alteration on river ecology.The results show that the hydrologic comprehensive alteration of Bashou hydrological station and Pingtang hydrological station are respectively 46.04%and 66.91%(the middle category).In other words,hydrologic alteration influenced the river ecology of Chengbi River,and Pingtang Hydrological Station is more seriously.Therefore,Pingtang hydrological station is considered to be a dangerous section of river ecology.Then,Fisher optimal segmentation method and vector statistics method were used to stage flow of Pingtang hydrological station under the hydrologic alteration.The results show that the non-flood season can be divided into four periods(Nov.1-Dec.20,Dec.21-Feb.10,Feb.11-Mar.10,Mar.11-Mar.31)before hydrological alteration,and three periods(Nov.1-Nov.20,Nov.21-Jan.31,Feb.1-Mar.31)after hydrological alteration.The flood season can be divided into five periods(before hydrological alteration:Apr.1-Apr.30,May.1-Jun.10,Jun.11-Aug.31,Sep.1-Sep.20,Sep.21-Oct.31;after hydrological alteration:Apr.1-May.10,May.ll-May.20,May.21-Aug.31,Sep.1-Sep.20,Sep.21-Oct.31).Temporal dividing will affect the results of ecological water requirement.Finally,the ecological water requirement under the hydrologic alteration was calculated by staged ecological water requirement method,and the differences were analyzed.Considering the impact of the environment changed,the ecological water requirement of Pingtang hydrological station in Chengbi River is:6.60m3/s(Nov.1-Nov.20),3.83m3/s(Nov.21-Jan.31),1.79m3/s(Feb.1-Mar.31),3.87m3/s(Apr.1-May.10),16.06m3/s(May.11-May.20),28.30m3/s(May.21-Aug.31),39.71m3/s(Sep.l-Sep.20),15.86m3/s(Sep.21-Oct.31).