嫩江流域湿地生态需水量分析与预估

探讨了嫩江流域湿地生态需水量的计算方法,并对流域内不同降水频率下湿地生态需水量进行了计算。在此基础上,选择CMIP全球气候模式下RCP2.6、RCP4.5和RCP8.5等3种排放情景,预测2030年、2050年和2100年嫩江流域湿地生态需水量的变化趋势。研究结果表明:不同降水频率下的流域湿地生态需水量分别为丰水年70.284亿m3,平水年118.696亿m3,枯水年169.343亿m3,反映了其与气候条件的相关性。3种排放情景下湿地生态需水量变化受到最高、最低气温和降水量变化的共同影响,其中RCP2.6情景下需水量呈先增加后减少的趋势;RCP4.5和RCP8.5情景下需水量整体呈增加趋势,到2100年分别达到147.337亿m3和132.659亿m3。气候变化条件下,如何协调水资源需求间的矛盾,维持湿地生态系统健康稳定,将是未来研究关注的重点。

Analysis and prediction of wetland ecological water requirements in the Nenjiang Basin

As in the case of most ecosystems, freshwater wetlands can be affected by climate change, which can alter wetland hydrology, water quality, and ecological health. Freshwater wetlands provide a number of valuable ecosystem activities, including carbon sequestration, primary productivity, floodwater storage, nutrient processing, and sediment stabilization. Further, they contribute to the high biodiversity of vegetation, macro invertebrates, fish, amphibians, reptiles, birds, and mammals. The Nenjiang Basin is one of the most important crop-production regions in China. A large portion of the headwaters of the river''s basin is located at relatively higher latitude and higher altitude regions, and the natural wetlands occupy approximately 15% of the total area of the Nenjiang Basin, supporting a large number of terrestrial and aquatic organisms. However, since 1978, approximately 28% of the wetland area has been drained and converted into agricultural fields or urban development land. The conversion of wetlands for agricultural purposes and urbanization has created considerable stress on the ecological health of the Nenjiang region. Although the effects of climate change are not yet fully understood, it could be an additional source of stress for already deteriorated regional ecosystems because of the reductions in the wetland area. In addition, since the natural wetlands of the Nenjiang Basin occupy a large area, it is also one of China''s most important wetland preservation areas. This area has experienced substantial changes in climate and land use/cover, which has led to serious water resource problems. Recent studies have shown that the regional climate has become warmer and drier, and the runoff in the Nenjiang Basin has declined since the 1950s. The predicted wetland ecological water requirements were 70.284 billion m³, 118.696 billion m³, and 169.343 billion m³ during high precipitation, flat precipitation, and low precipitation years, reflecting its correlation with the climatic conditions. Furthermore, changes in the annual maximum temperature, annual minimum temperature, annual average temperature, and precipitation were calculated from 1906 onward and projected to 2100. The annual minimum temperature showed a relatively significant increasing trend compared to the other measured factors, especially the annual maximum temperature. The changes in the maximum temperature and minimum temperature, resulting in narrowing of the diurnal temperature range, could cause the crop growth cycle to delay or advance. On the basis of the previous calculation, we selected the fifth phase of the Couple Model Intercomparison Project (CMIP5) simulations of global climate models to predict the wetland ecological water requirements from 2030 to 2100. In addition, three climatic emission scenarios were chosen, Representative Concentration Pathways (RCP) 2.6, 4.5, and 8.5. The results showed that the maximum temperature, minimum temperature, and precipitation jointly affected wetland ecological water requirement. Specifically, wetland ecological water requirement under RCP2.6 scenarios showed a decreasing trend after an initial increase, while the RCP4.5 and RCP8.5 scenarios showed an increasing trend in which by 2100, the wetland ecological water requirement reached 147.337 billion m³ and 132.659 billion m³, respectively. We believe that future studies must focus on how to coordinate and balance the water requirements and maintain the sustainable development of wetlands.