Synergistic effects of multiple driving factors on the runoff variations in the Yellow River Basin,China

River runoff plays an important role in watershed ecosystems and human survival, and it is controlled by multiple environmental factors. However, the synergistic effects of various large-scale circulation factors and meteorological factors on the runoff on different time-frequency scales have rarely been explored. In light of this, the underlying mechanism of the synergistic effects of the different environmental factors on the runoff variations was investigated in the Yellow River Basin of China during the period 1950-2019 using the bivariate wavelet coherence (WTC) and multiple wavelet coherence (MWC) methods. First, the continuous wavelet transform (CWT) method was used to analyze the multiscale characteristics of the runoff. The results of the CWT indicate that the runoff exhibited significant continuous or discontinuous annual and semiannual oscillations during the study period. Scattered inter-annual time scales were also observed for the runoff in the Yellow River Basin. The meteorological factors better explained the runoff variations on seasonal and annual time scales. The average wavelet coherence (AWC) and the percent area of the significant coherence (PASC) between the runoff and individual meteorological factors were 0.454 and 19.89%, respectively. The circulation factors mainly regulated the runoff on the inter-annual and decadal time scales with more complicated phase relationships due to their indirect effects on the runoff. The AWC and PASC between the runoff and individual circulation factors were 0.359 and 7.31%, respectively. The MWC analysis revealed that the synergistic effects of multiple factors should be taken into consideration to explain the multiscale characteristic variations of the runoff. The AWC or MWC ranges were 0.320-0.560, 0.617-0.755, and 0.819-0.884 for the combinations of one, two, and three circulation and meteorological factors, respectively. The PASC ranges were 3.53%-33.77%, 12.93%-36.90%, and 20.67%-39.34% for the combinations one, two, and three driving factors, respectively. The combinations of precipitation, evapotranspiration (or the number of rainy days), and the Arctic Oscillation performed well in explaining the variability in the runoff on all time scales, and the average MWC and PASC were 0.847 and 28.79%, respectively. These findings are of great significance for improving our understanding of hydro-climate interactions and water resources prediction in the Yellow River Basin.     

开启“南竹北移”新篇章 助力黄河流域生态保护和高质量发展

中国“南竹北移”始于20世纪50年代，是适应当时国家经济和社会发展的需要而采取的一项战略措施。经过60余年的曲折发展，在新的时代背景下“南竹北移”再次迎来重要发展机遇。站在生态文明建设的新起点上，回顾“南竹北移”发展历程，总结经验和教训，展望发展潜力，探索发展路径，无疑有着重要的现实意义。文中综述了中国“南竹北移”的发展历程、取得的经验，介绍了“南竹北移”工作的最新进展以及进一步发展的路径，以期为新时代发挥竹子优势、推动黄河流域生态保护和高质量发展以及加快我国生态文明建设和乡村振兴提供借鉴。     

Temporal Dynamics of Sediment Sources in an Urbanizing Mediterranean Catchment

The identification of sediment sources is important for catchment management, but few studies have been performed in Mediterranean areas. This study uses a multiproxy sediment fingerprinting approach to explore sources and dynamics of fluvial sediments in a rapidly urbanizing Portuguese peri‐urban catchment. X‐ray fluorescence was used to characterize the elemental geochemistry of sediments collected within the stream network after three storm events in 2012 and 2015. A range of statistical techniques, including hierarchical cluster analysis, was used to identify discriminant sediment properties and similarities between fine bed sediment samples of tributaries and downstream sites. Quantification of sediment supply from upstream sub‐catchments was undertaken using established sediment fingerprinting approaches. The geochemistry of the sediments was found to be influenced by both lithology and land‐use changes. In 2012, the sandstone sub‐catchment provided 75% of the <63 μm and 94% of the 63–125 and 125–2000 μm sediment, mostly from an Enterprise Park site undergoing deforestation and construction (covering 5% of the catchment area), with most of the remaining sediment deriving from the construction of a major road (1% of the catchment) in the limestone sub‐catchment. In 2015, planned and accidental retention basins below the Enterprise Park and major road sites, respectively, prevented some sediment from reaching the stream network, thereby reducing their importance as sediment sources. Sediment mobilization in urban areas with paved roads was small in comparison, but characterized by high heavy metal concentrations. The sediment fingerprinting approach adopted shows promise in identification of the main sources of sediments, necessary to underpin improved peri‐urban management strategies. Copyright © 2017 John Wiley & Sons, Ltd.     

湟水流域农业可持续发展面临的困境

湟水流域农业的持续发展，关系到青海省经济的持续发展，目前道水流域农业持续发展所面临的形势是严峻的，具体表现为耕地急剧减少，人地矛盾日趋尖锐，水资源不足且水染污严重，耕地后备资源不足，农业资源破坏严重，水土流失严重．土地质量劣化，自然灾害频繁，湟水河谷区次生盐渍化潜在威胁较大，农民问题日益突出等。正确认识和分析这些问题，是湟水流域农业可持续发展的前提。     

近40年洮河流域干燥度变化趋势分析

利用洮河流域7个气象站1971—2010年的地面气象观测资料，根据Holdridge生命地带模型对洮河流域近40 a的干燥度变化进行了分析。结果表明：近40 a洮河流域内可能蒸散率（PER）以0.02·10a^-1～0.07·10a^-1的趋势上升，20世纪90年代后PER的平均值比20世纪90年代前上升了0.12，洮河流域从20世纪90年代开始出现了明显的变干的趋势；近40 a洮河流域温度呈明显上升趋势，上升趋势为0.32～0.54℃·10a^-1，20世纪80年代末到90年代洮河流域气温出现了暖突变；降水量呈减少的趋势，其中以中、下 游减少最明显，减少趋势为13.3～21.8 mm·10a^-1；洮河流域出现了明显的暖干化趋势。     

松辽流域辽宁段水资源管理博弈分析

通过引入博弈理论把松辽流域辽宁段水资源管理中各利益主体的关系分为区域与区域和流域与区域两个层次,并分别进行博弈分析,进而找出导致水资源管理低效率的制度根源,提出了更加优化的"三位异体"的综合性流域机构管理与区域水务一体化管理相结合的管理模式及建立协调机制的对策建议。     

生物措施对柴达木盆地弃耕盐碱地效应分析

利用生物技术改良柴达木盆地弃耕盐碱地,3年结果表明,全盐量随着苜蓿种植年限的增加而降低.0～30cm耕作层全盐量由试验前的1.518%下降到0.12%,脱盐率达91.7%,盐分表聚现象已不明显.土壤盐分季节变化呈U型曲线,建植人工草地后,初级生产力明显提高.试验区植物群落的物种数、多样性指数、均匀度均高于对照区.     

四川盆周山区发展特色优质猕猴桃的优势与对策

通过对四川盆周山区发展特色优质猕猴桃的国际市场前景、生产现状、条件优势分析,提出了相应的对策和建议：发挥品种资源优势,推行规范化的综合配套生产技术;培育龙头企业,创立优势品牌;搞好产业结构调整,发展新兴生态产业。     

Soil erosion and runoff response to plant‐cover strips on semiarid slopes (SE Spain)

Over a four‐year period (1997–2000), soil loss and surface‐runoff patterns were monitored in hillside erosion plots with almond trees under different plant‐cover strips (thyme, barley and lentils) on the south flank of the Sierra Nevada (Lanjaron) in south‐eastern Spain. The erosion plots (580 m a.s.l.), located on a 35 per cent slope, were 144 m² (24 m×6 m) in area. The plant‐cover strips, 3 m wide, ran across the slope. The most effective plant cover proved to be thyme, reducing soil loss by 97 per cent and runoff by 91 per cent, compared to bare soil. Barley reduced soil loss by 87 per cent and runoff by 59 per cent, compared to bare soil, while these percentages were 58 per cent and 18 per cent for lentils. Thyme proved 77 per cent more effective than barley and 93 per cent more effective than lentils in reducing soil loss; thyme was also 79 per cent more effective than barley and 90 per cent more than lentil in blocking runoff. The present study demonstrates the effectiveness of plant‐cover strips in controlling soil erosion and runoff on sloping agricultural land. Copyright © 2005 John Wiley & Sons, Ltd.     

清涧河流域近50年径流时间变化特征及趋势分析

采用清涧河延川水文站近50年径流序列资料,运用不均匀系数、调节系数、集中度(期)、变差系数和极值比等指标分析径流时变特征,应用Mann-Kendall趋势分析法检验流域径流变化趋势。结果表明:1)清涧河流域径流的年内分配曲线呈现出单峰曲线,径流主要集中于7—9月份,约占全年平均径流量58%;2)1990以来,年内分配不均匀性和集中程度趋于减小;3)2000—2009年流域径流年际变异最大,且在不同时段径流年际变异差异较大;流域年径流量呈现明显下降趋势,20世纪80年代是流域径流丰枯转折点,并在2000年后进入严重枯水期。清涧河流域径流演变呈现出明显的不均匀性、阶段性和趋势性,这种变化与降水和植被恢复导致下垫面特征改变有关。