China Institute of Water Resources and Hydropower Research, Beijing, 100038, China.
Research Center on Flood and Drought Disaster Reduction of the Ministry of Water Resources, Beijing, 100038, China.
Environ Sci Pollut Res Int. 2018 Feb;25(5):4570-4583. doi: 10.1007/s11356-017-0790-8. Epub 2017 Nov 30.
Diffuse nutrient loss is a serious threat to water security and has severely deteriorated water quality throughout the world. Xin'anjiang catchment, as a main drinking water source for Hangzhou City, has been a national concern for water environment protection with payment for watershed services construction. Detection of diffuse phosphorous (DP) pollution dynamics under climate change is significant for sustainable water quality management. In this study, the impact of projected climate change on DP load was analyzed using SWAT to simulate the future changes of diffuse components (carriers: water discharge and sediment; nutrient: DP) at both station and sub-catchment scales under three climate change scenarios (RCP2.6, RCP4.5, and RCP8.5). Results showed that wetting and warming years were expected with increasing tendencies of both precipitation and temperature in the two future periods (2020s: 20212030, 2030s: 20312040) except in the 2020s in the RCP2.6 scenario, and the annual average increasing ratios of precipitation and temperature reached - 1.793.79% and 0.481.27 °C, respectively, comparing with those in the baseline (2000s: 20012010). Climate change evidently altered annual and monthly average water discharge and sediment load, while it has a remarkable impact on the timing and monthly value of DP load at station scale. DP load tended to increase in the non-flood season at Yuliang due to strengthened nutrient flushing from rice land into rivers with increasing precipitation and enhanced phosphorous cycle in soil layers with increasing temperature, while it tended to decrease in the flood season at Yuliang and in most months at Tunxi due to restricted phosphorous reaction with reduced dissolved oxygen content and enhanced dilution effect. Spatial variability existed in the changes of sediment load and DP load at sub-catchment scale due to climate change. DP load tended to decrease in most sub-catchments and was the most remarkable in the RCP8.5 scenario (2020s, - 9.002.63%; 2030s, - 11.167.89%), followed by RCP2.6 (2020s, - 10.002.90%; 2030s, - 9.006.63%) and RCP4.5 (2020s, - 6.815.49%, 2030s, - 10.00~9.09%) scenarios. Decreasing of DP load mainly aggregated in the western and eastern mountainous regions, while it tended to increase in the northern and middle regions. This study was expected to provide insights into diffuse nutrient loss control and management in Xin'anjiang catchment, and scientific references for the implementation of water environmental protection in China.
养分扩散损失是对水安全的严重威胁，已导致世界各地水质严重恶化。新安江流域作为杭州市主要饮用水源地，一直是国家关注的水环境保护区，并已采取流域服务付费措施来进行水环境保护。在气候变化背景下，检测扩散磷（DP）污染动态对于可持续水质管理具有重要意义。本研究利用 SWAT 分析了未来气候变化对 DP 负荷的影响，以模拟三种气候变化情景（RCP2.6、RCP4.5 和 RCP8.5）下，站和子流域尺度上扩散组分（载体：径流量和泥沙；养分：DP）的未来变化。结果表明，除 RCP2.6 情景下的 2020 年代外，未来两个时期（2020 年代：20212030 年，2030 年代：20312040 年）的湿润和温暖年份预计会增加，降水和温度的年平均增长率分别为-1.79%3.79%和 0.48%1.27°C，与基准期（2000 年代：20012010 年）相比。气候变化显著改变了年平均和月平均径流量和泥沙负荷，而对站尺度 DP 负荷的时间和月值有显著影响。由于降水增加导致稻田养分向河流冲刷增强，以及土壤层磷循环增强，导致 2020 年代雨粮 DP 负荷在非汛期增加，而 2020 年代雨粮和大多数月份的屯溪 DP 负荷在汛期减少，这是由于溶解氧含量降低和稀释效应增强，限制了磷的反应。由于气候变化，子流域尺度上泥沙负荷和 DP 负荷的变化存在空间变异性。在 RCP8.5 情景下（2020 年代，-9.00%2.63%；2030 年代，-11.16%7.89%），DP 负荷有下降趋势，且在 RCP8.5 情景下最为显著，其次是 RCP2.6（2020 年代，-10.00%2.90%；2030 年代，-9.00%6.63%）和 RCP4.5（2020 年代，-6.81%5.49%，2030 年代，-10.00%~9.09%）情景。DP 负荷的减少主要集中在西部和东部山区，而在北部和中部地区则有增加的趋势。本研究预期能为新安江流域的扩散养分流失控制和管理提供见解，并为中国实施水环境保护提供科学参考。
