Sutdy On Adjusting Flow Measures To The Effects Of Ecological Restoraiton Of Damaged Rivers Of South China

Adjusting flow measures （flap gate and make-up water measures） have beenconstructed on Qing hu reach of Guan lan river in Shenzhen to regulate current. The riverhealth status has been improved after three years of ecological restoration. This thesis aimsat analysis the restoration effects of river health, reveal the mechanism of river ecologicalrestoration, provide scientific reference and theoretical bases for related research in thefuture.By means of research, the author took an assessment of ecological restoration effectsand river health status of the Guan lan river, and took some preliminary explorations onwhat kind of habitat suit best for the creatures. Using the international evaluation systems,took assessments from three aspects. including hydrological indexes （velocity, depth,sediment）, water quality indexes （DO、BOD₅、CODcr、NH4-N、TN、TP）, biological indexes（riparian vegetation, phytoplankton, zoobenthos, fish） respectively.Control river sediment particle size of multitude at0.5²mm sandy particle size,Experimental reach particle size greater than2mm, Most in greater than5mm diameter ofthe substrate. Results reflect through the river sediment physical habitat suitability index,Repair reaches suitability index is an average of0.298was significantly higher thancontrol reaches0.225;Experimental reaches flow rate, depth type is more diverse than thecontrol reaches,by of Habitat diversity model to reflect, Habitat diversity of theexperiment reaches72was significantly higher than control reaches16The DO in the experimental reach is4.81mg/L was significantly higher than that inthe control reach1.39mg/L, and the DO has reached the national standardⅢ; the contentof NH4-N、TN、TP in the experimental reach is lower than that in the control reach,however, the content of NH4-N、TN is still worse than the national standardⅤ, thecontent of TP meet the national standardⅣ; CODcrin the experimental reach issignificantly lower than that in the control reach, and reached the national standardⅣ;BOD₅in the experimental reach higher than that in the control reach, reached the nationalstandardⅤ.Shannon-Weaver index and Margalef index of riparian vegetation in the experimentalreach Were2.645,3.896, is significantly higher than the control reach1.872,2.205, Pielousindex are similar between experimental reach and control reach. All the Shannon-Weaverindexes、Margalef indexes and Pielous indexes of phytoplankton and zoobenthos in theexperimental reach were higher than the control reach. The species dominance of diatoms in the control reach is low,and rich in the experimental reach. The phytoplankton datashow that the control reach is between moderate pollution and heavy pollution, and theexperimental reach is slight pollution. The best habitat for the phytoplankton lies wherethe flow converge, the downstream of the flap gate habitat and the deep pool habitatfollows. Investigating the fish twice, Determination to control reaches the density of fishon March5to5/10³㎡, the experiments reaches11/10³㎡；April7determination tocontrol river fish density of10/10³㎡experimental reaches19/10³㎡.All the fish found inthe control reach are young fries, and the population age structure has little change.However the fish found in the experimental reach for the first time （5th March） are mainlyfries, and it developed a stable population age structure and was strong anti-interferencethe second time （17th April）. The catfish suit the deep pool best, but the tilapia prefer toliving in the weeds. The diversity of the zoobenthos in the experimental reach issignificantly higher than the control reach. The zoobenthos in the control reach mainlycomposed by oligochaeta. The zoobenthos data shows that the control reach is heavilypolluted, and the experimental reach is slight pollution. The habitat with weeds in theexperimental reach suit for the zoobenthos best, and the habitat of flow intersection in theshoal is second to the weeds habitat.Synthesizing the indexes of hydrology、water quality and biology showd, theecological restoration effect of the experimental reach is obviously. All of the indexes arebetter than the control reach. Description adjusting flow measures play a significant effectin damage and flow of ecological restoration in the South China, But water pollution isstill serious, Biodiversity to the degree of recovery is not enough, to be further recovery.