流域产输沙模型中考虑泥沙来源的动态粒径计算方法

为准确反映泥沙粒径分布特征在不同时间尺度上的变化过程,提高流域产输沙模型的模拟精度,以黄河干流玛曲水文站以上区域为研究对象,根据不同季节的泥沙来源不同这一特点,采用坡面、谷沟、河道各来源的泥沙量作为权重,基于WEP-SED分布式流域产输沙模型对流域产输沙过程中的综合泥沙中值粒径进行加权平均计算,并对采用泥沙固定粒径计算方法和不同来源的泥沙动态粒径计算方法的模型模拟的玛曲水文站输沙率进行比较。结果表明:与采用泥沙固定粒径计算方法相比,采用泥沙动态粒径计算方法可有效提高模型模拟精度,其NSE值从0.601提升至0.706;采用泥沙动态粒径计算方法模拟的泥沙中值粒径呈现汛期小、非汛期大的动态变化规律,其年内分布规律与实测资料一致。

基于三级汇流和产输沙结构的分布式侵蚀产沙模型

黄土丘陵沟壑区面临严重的土壤侵蚀问题,是黄土高原主要产沙区域,针对该区域的土壤侵蚀产沙模拟一直是黄河泥沙研究的热点。尽管如此,已有侵蚀产沙模型对坡面、沟壑侵蚀环节刻画并不完善,沟壑侵蚀过程的忽视限制了模型在沟壑区侵蚀产沙模拟的精度。为此,本文考虑了沟壑侵蚀的特殊性,从分布式水循环模型(the Water and Energy Transfer Processes in Large River Basins,简称WEP-L)的“坡面-河道”二级产汇流结构中单独分离出沟壑环节,提出了“坡面-沟壑-河道”的三级汇流和产输沙结构,从而构建了基于WEP-L的分布式侵蚀产沙物理模型(WEP-SED)。将WEP-SED应用于无定河流域白家川水文站控制区,模型得到的白家川1956—2010年月均输沙率过程与实测过程接近。结果表明,WEP-SED可有效应用于黄土丘陵沟壑区的侵蚀产沙模拟研究。此外,模拟的白家川沟壑环节多年平均侵蚀量约占该区域总侵蚀量的49%,且94%的沟壑侵蚀集中于7—9月。模拟结果充分说明该区域沟壑侵蚀的严重性,细化沟壑侵蚀过程对于提高该区域侵蚀产沙模拟精度具有重要意义。

基于分布式水沙模型的大夏河流域水沙过程演变机理

黄河上游水沙过程受气候和土地利用变化等因素影响,年际及年内分布差异较大。选择大夏河流域为研究区,对研究区的实测径流和输沙量进行趋势性分析,应用流域分布式水沙模型(WEP-SED)模拟流域水沙过程并采用多因子归因分析方法进行分析,探究大夏河流域在变化环境下的水沙演变规律。结果表明:大夏河流域年径流量下降速率为0.85亿m 3/10 a,年输沙量下降速率为66.25万t/10 a,趋势均为负持续性,输沙量的减小幅度是径流量的1.8倍;大夏河流域水沙过程主要受汛期降水、气温以及土地利用变化的影响,降水对径流量和输沙量减少的贡献率分别为-77.0%和-90.0%,气温对两者的贡献率分别为-29.7%和-16.5%,而土地利用变化对两者的影响呈现微增作用。

Glacier variations and their response to climate change in an arid inland river basin of Northwest China

Glaciers are a critical freshwater resource of river recharge in arid areas around the world.In recent decades,glaciers have shown evidence of retreat due to climate change,and the accelerated ablation of glaciers and associated impacts on water resources have received widespread attention.Glacier variations result from climate change,so they can serve as an indicator of climate change.Considering the climatic differences in different elevation ranges,it is worthwhile to explore whether different responses exist between glacier area and air temperature in each elevation zone.In this study,we selected a typical arid inland river basin(Sugan Lake Basin)in the western Qilian Mountains of Northwest China to analyze the glacier variations and their response to climate change.The glacier area data from 1989 to 2016 were delineated using Landsat Thematic Mapper(TM),Enhanced TM+(ETM+)and Operational Land Imager(OLI)images.We compared the relationships between glacier area and air temperature at seven meteorological stations in the glacier-covered areas and in the Sugan Lake Basin,and further analyzed the relationship between glacier area and mean air temperature of the glacier surfaces in July–August in the elevation range of 4700–5500 m a.s.l.by the linear regression method and correlation analysis.In addition,based on the linear regression relationship established between glacier area and air temperature in each elevation zone,we predicted glacier areas under future climate scenarios during the periods of 2046–2065 and 2081–2100.The results indicate that the glaciers experienced a remarkable shrinkage from 1989 to 2016 with a shrinkage rate of–1.61 km^2/a(–0.5%/a),and the rising temperature is the decisive factor dominating glacial retreat;there is a significant negative linear correlation between glacier area and mean air temperature of the glacier surfaces in July–August in each elevation zone from 1989 to 2016.The variations in glaciers are far less sensitive to changes in precipitation than to changes in air temperature.Due to the influence of climate and topographic conditions,the distribution of glacier area and the rate of glacier ablation first increased and then decreased in different elevation zones.The trend in glacier shrinkage will continue because air temperature will continue to increase in the future,and the result of glacier retreat in each elevation zone will be slightly slower than that in the entire study area.Quantitative glacier research can more accurately reflect the response of glacier variations to climate change,and the regression relationship can be used to predict the areas of glaciers under future climate scenarios.These conclusions can offer effective references for assessing glacier variations and their response to climate change in arid inland river basins in Northwest China as well as other similar regions in the world.

湖北省江海联运发展实施路径研究

基于对湖北省四类典型江海联运线路发展现状的梳理,分析湖北省江海联运发展存在的主要问题,有针对性提出湖北省江海联运发展路径,为湖北省内河航运高质量发展提供有益参考。