A Study On The Restoration Of Wetland Hydrological Connectivity In The Lower Reaches Of Songhua River

The hydrological connectivity of wetlands has been altered greatly in the lowerreaches of Songhua River, due to the intensive agricultural development and otheranthropogenic activities which lead to ecological degradation of wetlands. TheWetland Nature Reserve in lower reaches of the Songhua River was chosen to be thestudy area. Based on the information on meteorological, hydrological conditions, andcurrent ecological situation, the wetland hydrology database in the research area wasestablished firstly, on the basis of the exploration of hydrological network, thenaccording to the hydrology database restructures for connectivity were constructedand restored utilizing existing ditches, channel and water engineering construction;finally, the assessment of recovery project and optimization scheme were providedaccording to the connectivity index, water level, flooded area and water storagecapacity so as to realize the feedback mode design. The main conclusions were shownas follows:（1）The intensive anthropogenic activities, such as agriculture and animalhusbandry, cut off the connection between rivers and wetlands. According to theresults of hydrology monitoring and remote sensing, the ecological problems ofriparian wetlands, including decline of inflow water to the wetlands and undergroundwater level, were intensified recently resulting in poor wetland hydrologicalconnectivity, fragmentation and islanding of wetland, which may further leading tothe shrink of wetland area, and exert adverse influence on the structure, function andbiodiversity of wetland ecosystem.（2）The construction and implementation project were built to realizehydrological connectivity and restore wetland. Assessment of recovery was carriedout according to the connectivity index, water level, flooded area and water storagecapacity after connectivity: both the Integral Connectivity (HC) and Probability ofconnectivity (PC) increased with distance threshold. The average of Integral index ofConnectivity (HC) increased from0.062to0.374, Probability of Connectivity (PC)rose from0.083to0.379. The water level raised significantly, the average water level increased from1.5m to2.4m. The flooded area increased from2.21×106m2to2.72×106m2. Through inundation map of different levels, the wetland water volumeincreased from7.19×106m3to11.7×106m3.（3）From the dHC and dPC results, we can identify which patches played animportant role in connectivity of wetland in the research area. It shows that theyfunction as the connective corridors with relative large area and strip type, and almostall of them locate in the channel of the research area. All of above indicates that it issignificant to maintain and recover the wetland connectivity. Therefore, differentmeasurements based on the important degree of each patches should be adopted torestore the wetland.