| The Nenjiang River basin is an important grain-production region withabundant wetlands in northeast China. Climate change and anthropogenicactivities have dramatically altered the spatial and temporal distribution ofregional stream discharge and water environment, which poses a serious threatto wetland ecosystems and water resources. In this paper, we analyzed theeffects of climate change and human activities on the wetland hydrology andwater resources, calculated wetland ecological water requirements, and putforward the schemes of water resources rational allocation, which wouldcontribute to the rationally and scientifically of hydrological management ofwater resources.(1) Meteorological and hydrological charateristics of the Nenjiang Rvierbasin over the past55yearsBased on the analysis of daily data of39meteorological stations in andaround the Nenjaing River basin, the temperature, precipitation andevapotranspiration were analyzed by ArcGIS software. The results showed thattemperature had an obvious increase trend in the past55years, the precipitationpattern also changed; the annual distribution of runoff showed a very uneventrend, which concentrated in the summer and autumn; the inter annual variationof runoff was obvious, which differed greatly between the high flow period anddrought period. The flood peak data was analyzed by the Pearson Ш frequencycurve method, we found that the hundred-year flood peak value wasQ12647m~31%=/s，and most of these flood take place in July to August, whichmainly based on rainwater type. (2) Evaluating the contribution of climate change and human activities onrunoffThe contribution of climate change and human activities on runoff wasanalyzed by the water balance method and the hydrological sensitivity analysismethod. The contribution of climate change to runoff was80.3%,72.3%and69.6%in upstream basin, midstream basin and downstream basin, respectively.Moreover, the impact of human activities on the Nenjiang River basin wasenhanced with the time.(3) Landscape pattern change and hydrological driving mechanism in thewetlands of Nenjiang River basinThe wetland landscape dynamics and its influencing factors were analyzedusing four wetland remote sensing data in1970s,1980s,1990s and2000s ofNenjiang River basin. The results showed that natural wetland area decreasedsignificantly, and swamp landscape fragmentation trend tended to be worse.There were many factors influencing the wetland landscape dynamics, but theprecipitation fluctuation and decrease of runoff were the most important reasons,the marsh area and runoff coefficient had a very significant positive correlation,the Pearson correlation coefficient was0.90. In addition, human activities,especially the land use/land cover change had important implications on wetlandlandscape, the substantial increase of farm land, reduction of grassland andwoodland will affect the water supply of wetland, resulting in shrinking of thewetland area and landscape feature changes. In addition, extreme weather eventwill play an important role on supplying water resources and restoringfloodplain wetland.(4) Wetland ecological water demand prediction in the future climate changescenariosThe suitable wetland ecological water demand was computed by calculatingthe water demand of vegetation, soil and wildlife habitat. The results showed that the suitable wetland ecological water demands in the Nenjiang Rvier basinwere16.9343billion m~3,11.8696billion m~3and7.0284billion m~3, respectively.Based on the CMIP5Global Climatic Model, the wetland ecological waterdemands in the future were predicted under the RCP2.6, RCP4.5and RCP8.5emission scenarios, the results were12.1223billion m~3，14.7337billion m~3and13.2659billion m~3.(5) Adaptation management for addressing climate change in the wetlandsof Nenjiang River basinFinally, through the analysis of situation of water resources, its developmentand utilization, we proposed engineering measures such as wetland conservationpriority, normal replenishment to the important wetlands, to manage the basinwetland water resources. |
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