Evaluation Of Ecological Engineering In Wetland Systems Basing On The Emergy Analysis Method

In this study,it is the main strategy to settle the problem in ecological restoration and protection on the perspective of the basin scale.In this work,it has been summarized the common ecological environmental threats,including non-point source pollution problems?mainly rural sewage pollution?,urbanization problems,ecological and environmental problems of the drawdown zone?DDZ?,aquaculture problems,blindness returning farmland to wetland,in the upper-middle reaches of the Yangtze River.In accordance with the basic theory,principles,ideas of the wetland ecological engineering designing,it had been propounded the design model of the ecological engineering and chose representative region to start demonstration project in this work,of which target was comprehensive ecological restoration,environmental management and wetland protection.In this study,researchers have made the emergy evaluation model of different demonstration projects,which were quantitative evaluation from the energy flow and material circulation.As a result of the emergy evaluation results and comparison with other work,the researcher put forward optimization strategy of different demonstration projects.In this study,the researcher focused the design ideas on the wetland ecological engineering,and used the mature theory to construct model of emergy sustainable evaluation of wetland ecological engineering.In this work,that was put forward a comprehensive project on the feasibility of restoration and protection of ecological environment in the upper-middle reaches of the Yangtze River System.At the same time,that was explored and put forward feasible strategies on the application of emergy model in small scale projects in the upper reaches of the Yangtze River.The main conclusions were as follows:In this study,the researcher had summarized the idea of the design on dike-pond?DP?engineering,carried out demonstration project and adapt emergy model to evaluation in the Pengxi River tributary Bai jia Creek riparian zone,which was based on the traditional wisdom of Mulberry fish ponds,aimed to soil erosion,non-point source pollution,loss of biodiversity and other issues in the Three Gorges Reservoir?TGR?area.According to the special conditions of DDZ with seasonal changes,this work had been built 25 stepped on"Tang-Tian"series-parallel connection mode?DP?in sloping land and started agricultural production activities.The economic value of agricultural products was 40441.92?/hm² in the DP?model I?,which was more than the control group?model II?.The production of the DP had more potential value because of the crops without fertilizers,herbicides and pesticides during planting.The result showed that the two models relied on different resources by means of the Emergy Analysis?EmA?.The Emergy Density?ED?on yield of both models were similar?model I was 3.99E+16 SEJ/year/ha,model II was 4.00E+16 SEJ/year/ha?,but the emergy investment of model II was greater than that of model I.Model I was higher than that of model II on renewable resources utilization.The agricultural emergy sustainability index?AESI?of model I system?2.4?was greater than that of model II system?0.5?,which indicated that the model I was stronger than that of model II on the sustainable development in the DDZ of the TGR.Compare with the"duck-rice"and"fish-rice"system,DP system had higher sustainability,more availability resources and lower environment load ratio?ELR?.The DP system had provided a good templet for the resource utilization of the gentle slope in the DDZ.In this part,the researcher used the ideas of the design on"sponge city structure"to carry out demonstration project and adapt emergy model to evaluation the multifunctional bio-swale system and raingarden system in Kaizhou,Chongqing municipality,which aimed to urban stormwater and flood,pavement imperviousness,loss of biodiversity and other issues during city development.It had been carried out about 2 years monitored work and built emergy model to evaluation.The study suggested that the design was according to terrain conditions,which was used pipeline to collect rainwater and surface runoff with high pollution loads,through bio-swale and rainwater garden to retention,interception,accommodation and infiltration.On one hand,it had made the pollutant be intercepted and purified in the unit,on the other hand,it could be retained rain in structure layer for the city water resource reuse and groundwater recharge conditions.During emergy model of the bio-swale,the ratio was8%of the renewable resources,so the proportion was higher of the non-renewable resources.The external investment resources were less than the local resources utilization,and the project sustainability was moderate.During the emergy model of the rainwater garden,the output was greater than the input.Meantime,this work was increased the type of the output,and the the protection of water resources was main part.The ELR was 3.35,which mean that the project has little effect on the original environmental system.The ESI was more than 1,so the sustainability was medium.Compared the design and evaluation with similar system in foreign,this work was aimed to design micro landform structure of the original green space in city system,and then reduce non-renewable resources,of which system was designed more complete.Emergy output was higher than similar system.Because of emergy evaluation in bio-swale and rainwater garden fewer,this study could provide a case.With the rapid urbanization,urban wetland units,such as bio-swale and rainwater garden,are effective measures to restore and protect the ecological environment in the upper-middle reaches of the Yangtze river.Due to the problem of the blindness in returning farmland to wetland in the middle reaches of the Yangtze River,this study was put forward a new mode,carried out the design and monitored in Zhu Lake farm in Hubei province.The work was indicated that it transformed the original farmland,of which were made shoal,pond,swale,island,polder land,lagoon,curved shore and other factors,to wetland units on the bank of lake.Concretely,it consistsed of the pond,polder and littoral-forest from the returning farmland.From the process of the emergy flowing,the output was more than the input.Compared with other system,the value of the returning farmland to wetlands project was far higher than the coastal wetland on the scientific cultural value,the habitats support and resource supply.But,the value of regulating the function was lower than the coastal wetland system.The emergy value of ecosystem service was shown as follows:scientific research>primary product supply>waste treatment>habitat maintenance>release O₂>fixed CO₂>climate adjustment.The ESI was 5.58.With the system gradual recovery,the sustainability was gradually enhanced,and the benefit was gradually increased.As the number of lakes increasing and the area of lakes expanding in the middle reaches of the Yangtze River,the capacity of storage the flood is improved the in the middle reaches of the Yangtze river.To solve the threat from the aquaculture in Tianlong Bay of Yidu city,Hubei province,this work was suggested that it was summarized the developmental pattern,put the plan into practice,monitored and built emergy model to evaluate.The aquaponics system was made up of the floating bed and cage.The floating bed floated on the surface of the water.The flowers or aquatic vegetables were planted on the bed,and the cage was submerged in the water.The roots were dispersed in the water through the floating bed,which were connected the above and under water spaces.The system was form a relatively complete ecosystem,which was mutualism-multilayer system in solid space.Through the emergy model counted,the results showed that the renewable resources were less than non-renewable resources.The output of the aquaponics system was not single fish but aquatic vegetables,nutrient element purification and fish.Furthermore,it was increased service feedback analysis.The feedback reflected the value of ecosystem restoration and ecosystem services,which was about 1/10 of the system output,and the ratio of plant to animal was 45.19:1,and the ratio of above to under water was 16.08:1.The ED of the systems was 3.73E+17 SEJ/yr/ha.The EYR was 3.964,the ELR was 5.623,and the ESI was 0.705.The system emergy output was greater than input.The aquaponics system was closer to the natural system,and the manual management interference was less,relatively.Also,the aquaponics system was similar to the extensive management mode.To meet the solution of the non-point source pollution problems,this work had been put forward design ideas of compound constructed wetland in farmhouse,which was carried out adaptability project with water quality and biodiversity monitoring.Then,it was constructed emergy model and made sustainable analysis.According to the high pollution and particulate matter sewage,this study was used step by step for multistage subsurface flow constructed wetland,which can save power energy input with utilization in mountainous slope conditions.The pond could not only purify the water quality,but also be the water storage structure of the multi-stage subsurface flow constructed wetland system,and also the water source for the irrigation around the vegetable fields.Through the emergy model and evaluation,this study was suggested that the artificial wetland design was compared with the single and compound system in this study,the total investment value was slightly higher than the composite system of artificial wetland system,but renewable resource utilization rate had little difference,and for the two systems,the purchase of non-renewable resource was the main input.The emergy yield rate of constructed wetland system was slightly larger than that of composite system.The output of the two systems was greater than the input,and the ELR was less than 3,which was indicated that the environmental impact was less.Compared with the similar system,the ESI of the system was higher than that of the biogas agriculture composite system,lower than the"pig biogas fish"system.The emergy feedback of the system was higher than that of"pig biogas fish"system.The ESI of the system was smaller than that of the traditional agricultural system.Through the water quality monitoring and biodiversity analysis,the adaptive artificial wetland unit could intercept and purify the water body into the basin system,and play a proper role for the reduction of water pollution substances in the basin.The benefit of the artificial wetland system was obvious,and the artificial wetland system of"ecological kidney"was an effective way to solve the problem of rural sewage treatment with scattered terrain and wide coverage.The developments of the wetland systems model in the reaches.Facing the threatening factor for different conditions and region,some kinds of adaptable wetland ecological engineering,such as dike-pond,bio-swale,raingarden,returning farmland to wetland,aquaponics,constructed wetland,were bring out with new ideas to solve outstanding environment problem and refurnish impaired systems.