Impact of land-cover and climate changes on runoff of the source regions of the Yellow River

After dividing the source regions of the Yellow River into 38 sub-basins, the paper made use of the SWAT model to simulate streamflow with validation and calibration of the observed yearly and monthly runoff data from the Tangnag hydrological station, and simulation results are satisfactory. Five land-cover scenario models and 24 sets of temperature and precipitation combinations were established to simulate annual runoff and runoff depth under different scenarios. The simulation shows that with the increasing of vegetation coverage annual runoff increases and evapotranspiration decreases in the basin. When temperature decreases by 2oC and precipitation increases by 20%, catchment runoff will increase by 39.69%, which is the largest situation among all scenarios.     

黑河地区高分辨陆地分类的综合分析

本文综合了国内外诸种有关资料,借鉴了国际上较通用的下垫面特征分类标准,也结合黑河地区下垫面的实际情况,对HEIFE试验区及其邻近地区的下垫面特征(包括地表特征、土壤特征及地形高度)进行归纳分类,形成了两种高分辨率(分别约为6km×6km及3km×3km)的下垫面特征的格点化资料,可供该地区地气相互作用研究用。     

新疆喀什噶尔河流域水资源质量保护及对策

喀什噶尔河流域水环境系统十分脆弱, 运用环境容量总量控制、水质模型等方法进行了重点河段污染物控制量计算, 合理的划分水功能区, 拟订可行的水资源保护目标, 确定了污染物总量控制方案, 为水资源保护、水资源的可持续利用提供依据.     

塔里木河下游地区滴灌沙枣防护林地土壤盐分分布特征

为了研究不同滴灌措施对极端干旱区防护林土壤盐分的淋洗作用,以沙枣（Elaeagnus angustifolia）防护林作为研究对象,对塔里木河下游喀拉米吉绿洲沙枣防护林开展了灌溉与不灌溉、不同滴头距离、不同滴灌年限处理的试验。结果表明：①不灌溉林地土壤盐分含量与流动沙丘相似,流动沙丘土壤盐分分布的空间异质性大于不灌溉林地。滴灌林地土壤含盐量低于不灌溉林地。②1.5 m滴头距离处理与其他处理相比压盐碱效果显著（P<0.01）。1.5 m与3 m滴头距离处理在50 cm土体中含盐量差异达极显著水平（P<0.01）,前者比流动沙丘低30.5%～32.7%、后者比流动沙丘高17.1%～13.3%。与3 m滴头距离处理相比,1.5 m滴头距离处理产生水盐运移的“互作”影响,盐峰下移。③滴灌后的第1、2、3年,林地的土壤盐分分别下降至30 cm、50 cm和70 cm以下,基本对沙枣根系生长没有影响。随着滴灌次数增加,根系生物量逐渐增大,根系附近土壤盐分逐渐减少。滴灌能使防护林的根系分布上移,大部分在10～65 cm土层内,土层越深,林木的根系越少。④灌水季节末期,不同林龄的防护林在120 cm土体的含盐量表现为：1 a林＞2 a林＞6 a林,说明滴灌对林龄大的防护林淋洗效果更为明显;非灌溉季节里,防护林的林龄越大,其土壤盐分表聚现象越明显。     

三角洲感潮河段洪潮水位频率分析方法的初步研究

根据珠江三角洲感潮河段年最高洪潮水位存在长期上升趋势的事实，提出了河口区感潮河段洪潮水位频率分析一种新的计算方法，新方法的分析结果表明，未来不同年代同频率的设计洪潮水位各不相同，也存在相应的长期变化趋势。以灯笼山站为例，新方法计算的2030年和2050年的百年一遇设计洪潮水位分别为3.12m和3.28m，比传统频率分析方法计算的结果分别高出0.24m和0.40m。建立有关部门在制定河口区的防洪标准时，根据洪潮水位的长期变化趋势作相应的动态调整，以适应河口区洪潮水位变化的实际情况。     

Changjiang River sediment delivering into the sea in response to water storage of Sanxia Reservoir in 2003

1 IntroductionHuman activitieshavebeen stronglyaffecting theworld river sedimentsupply to the oceans since the19thor20thcentury(StanleyandW arne,1993;Fanos,1995;Sm ithandW inkley,1996;Stanley,1996;Yang,Shi,etal.,2004;Yang,Zhao,etal.,2002).Thesedi-m enttra…     

Channel change at Toudaoguai Station and its responses to the operation of upstream reservoirs in the upper Yellow River

The application of dams built upstream will change the input conditions, including water and sediment, of downstream fluvial system, and destroy previous dynamic quasi-equilibrium reached by channel streamflow, so indispensable adjustments are necessary for downstream channel to adapt to the new water and sediment supply, leading the fluvial system to restore its previous equilibrium or reach a new equilibrium. Using about 50-year-long hydrological, sedimentary and cross-sectional data, temporal response processes of Toudaoguai cross-section located in the upper Yellow River to the operation of reservoirs built upstream are analyzed. The results show that the Toudaoguai cross-section change was influenced strongly by upstream reservoir operation and downstream channel bed armoring thereafter occurred gradually and extended to the reach below Sanhuhekou gauging station. Besides, median diameter of suspended sediment load experienced a three-stage change that is characterized by an increase at first, then a decrease and an increase again finally, which reflects the process of channel bed armoring that began at Qingtongxia reservoir and then gradually developed downstream to the reach below Sanhuhekou cross-section. Since the joint operation strategy of Longyangxia, Liujiaxia and Qingtongxia reservoirs was introduced in 1986, the three-stage change trend has become less evident than that in the time period between 1969 and 1986 when only Qingtongxia and Liujiaxia reservoirs were put into operation alone. In addition, since 1987, the extent of lateral migration and thalweg elevation change at Toudaoguai cross-section has reduced dramatically, cross-sectional profile and location tended to be stable, which is beneficial to the normal living for local people.     

长江口水下三角洲137Cs最大蓄积峰的分布特征

在长江口水下三角洲地区,用 137Cs进行沉积速率的测定时,一般认为 137Cs最大值所在层位为1963年沉积层。本文通过建立模型,对此进行了计算验证。模型中利用日本东京地区的 137Cs年平均大气沉降通量,再通过东京与上海两地的降水量进行校正,并根据不同的沉积速率和取样间隔分别计算出 137Cs剖面中的最大值范围,再将理论计算值与实测值进行对比。通过模型的计算,发现理论上沉积物中出现 137Cs最大值的层位均为1963年沉积层,将理论最大值范围与本研究所测11根柱样以及前人在本区域所测6根柱样 137Cs最大值的对比,发现其中有9根柱样的最大值在理论计算值范围之内。总体上看,理论值与实测值有较好的对应关系,理论值范围基本可作为衡量实测最大值是否为1963年沉积物所在层位的评判标准之一。本文对利用大气沉降 137Cs信息计算沉积物中 137Cs的分布进行了有益的尝试。     

黄河流域经济发展与生态环境耦合协调的时空格局研究

生态环境是经济发展的基础,合理的有序的经济发展既是生态环境的内在要求,也是加强环境保护的重要支撑。推动黄河流域经济与生态环境协调发展是该流域实现生态保护与高质量发展的前提。文中以黄河流域91个地市（州、盟）为研究单元,构建经济发展和生态环境耦合协调评价指标体系,并运用熵值法、耦合协调模型及相对发展度模型对2005—2018年黄河流域经济发展与生态环境耦合协调度时空格局进行分析。结果表明：（1）从时序分析层面看,黄河流域经济发展与生态环境耦合度整体呈小幅波动下降态势,耦合水平较低,长期处于中度耦合的颉颃阶段;协调度总体呈波动下降趋势,主要从濒临失调阶段向轻度失调阶段过渡,协调度水平有待提升;相对发展度整体呈大幅波动上升态势,具体表现为随着时间的推移总体呈现生态环境逐渐滞后于经济发展的状态;（2）从空间分析层面看,耦合度呈现由上游向中下游逐渐增强的空间格局,协调度呈现以省会城市以及沿海城市为高值中心连片分布的格局,具有明显的空间差异性,相对发展度随着时间的推移,整体呈现由分散向集中、由个别到整体的空间形态。     

基于决策树的多角度遥感影像分类

快速准确地获取土地利用/覆被信息是遥感领域研究的一个热点课题.本文用5种决策树分类器及MISR多角度数据,对塔里木河下游地区进行土地覆被分类研究.通过对不同波段和观测角数据组合形成的6个数据集进行分类比较发现:(1)无论使用哪种分类器,相比于天底角观测方式,多角度观测都能获得更高的分类精度,特别是能显著提高灌木,林地和草地类型的分类精度,说明多角度观测能有效地反映地物的反射异质性信息,更好地区分地物.(2)与MLC分类法相比,决策树算法的分类精度更高,特别是随机森林和C 5.0方法最为突出,说明决策树的分类能力要优于MLC法.使用多角度数据集时,这种差别更明显,说明决策树能更有效地利用多角度信息.(3)4种决策树算法(J48,Random Forest,LMT,C 5.0)使用近红外波段的分类效果好于使用红光波段的分类效果,说明近红外波段能提供更多的地物反射异质性信息.