基于变点识别的区域河川径流量特征值变异研究

基于变点原理,运用最大似然比和西沃兹信息标准方法,对广东省4种径流量序列进行均值变点和方差变点的识别,研究存在变点的河川径流量序列、时间位置、空间分布及变点后的特征值变化状况,以揭示广东省河川径流量时空变异特点。结果发现:广东省河川年径流量和汛期径流量序列的一致性较好,而枯期径流量和最小月径流量序列的特征值变点具有普遍性,年均值明显增加,年际离散程度增大,时间位置主要为1972-1973年和1981年两个时间段。枯期径流量序列均值变点的典型地区主要为东江流域,方差变点的典型地区主要为北江流域、韩江流域、粤西地区和珠江三角洲;最小月径流序列主要为均值变点,典型地区有东江流域、韩江流域;而北江入珠江三角洲的河川径流量变异尤其典型,4种径流序列均存在均值变点和方差变点。     

Predicting the Planform Configuration of the Braided Toklat River,Alaska, With a Suite of Rule‐Based Models1

Abstract: An ensemble of rule‐based models was constructed to assess possible future braided river planform configurations for the Toklat River in Denali National Park and Preserve, Alaska. This approach combined an analysis of large‐scale influences on stability with several reduced‐complexity models to produce the predictions at a practical level for managers concerned about the persistence of bank erosion while acknowledging the great uncertainty in any landscape prediction. First, a model of confluence angles reproduced observed angles of a major confluence, but showed limited susceptibility to a major rearrangement of the channel planform downstream. Second, a probabilistic map of channel locations was created with a two‐parameter channel avulsion model. The predicted channel belt location was concentrated in the same area as the current channel belt. Finally, a suite of valley‐scale channel and braid plain characteristics were extracted from a light detection and ranging (LiDAR)‐derived surface. The characteristics demonstrated large‐scale stabilizing topographic influences on channel planform. The combination of independent analyses increased confidence in the conclusion that the Toklat River braided planform is a dynamically stable system due to large and persistent valley‐scale influences, and that a range of avulsive perturbations are likely to result in a relatively unchanged planform configuration in the short term.     

香港吐露港地区河流水质管理效果研究

为探讨香港水质管理的措施及效果,本文对香港吐露港地区5条河流10个监测点1985—2014年的地表水质数据进行分析,观察水体整治管理前后污染物浓度的变化。结果表明:10个监测点的氨氮、BOD_5、COD和TP的浓度均逐年下降,上下游共同努力,使各项污染物得到很大程度的削减,并且治理前后的浓度存在明显统计学差异(p0.05),且治理之后各项污染物年均浓度趋于平稳,达到标准以内。由此可以看出,香港地区水质管理效果的显著与其所实施的《水污染管制条例》、禽畜饲养禁制区设立与吐露港及牛尾海污水收集整体计划密不可分。随着国务院颁布的《水污染防治行动计划》的施行,香港吐露港地区治理的措施可为我国现阶段黑臭水体整治工作所借鉴。     

Evaluating the Slope‐Area Method to Accurately Identify Stream Channel Heads in Three Physiographic Regions

Estimation of stream channel heads is an important task since ephemeral channels play a significant role in the transport of sediment and materials to perennial streams. The slope‐area method utilizes digital elevation model (DEM) and related information to develop slope‐area threshold relationships used to estimate the position of channel heads in the watershed. A total of 162 stream channel heads were mapped across the three physiographic regions of Alabama, including the Southwestern Appalachians (51), Piedmont/Ridge and Valley (61), and Coastal Plains (51). Using Geographic Information System and DEM, the local slope and drainage area for each mapped channel head was calculated and region‐specific models were developed and evaluated. Results demonstrated the local slope and drainage area had an inverse and strong correlation in the Piedmont/Ridge and Valley region (r² = 0.71) and the Southwestern Appalachian region (r² = 0.61). Among three physiographic regions, the weakest correlation was observed in the Coastal Plain region (r² = 0.45). By comparing the locations of modeled channel heads to those located in the field, calculated reliability and sensitivity indices indicated model accuracy and reliance were weak to moderate. However, the slope‐area method helped define the upstream boundaries of a more detailed channel network than that derived from the 1:24,000‐scale National Hydrography Dataset, which is commonly used for planning and regulatory purposes.     

流域水体生态修复技术探讨

针对河道等自然流域的水体污染物进行生态治理,作者提出运用三个独立步骤而形成一道自然水体修复功能：第一步,优选良性微生物株群并持续发展与供给;第二步,运用河道功能增加水中的溶解氧;第三步,建立流域水体生物链,从而达到流域水体消纳污染物的自净效果。     

渗流式生物床处理污染河水性能的研究

渗流式生物床是受严重污染小型河流强化治理的适宜技术,在中国北方河流污染的治理中有良好的应用前景。冬季由于水温较低带来的去除效果下降是北方河流污染治理的关键问题,本研究在现场中试基础上,考察了一年四季不同水温条件下渗流式生物床处理污染河水的性能。研究表明:渗流式生物床对河水中的CODCr、NH3-N、浊度有较好的去除效果。去除效果和去除负荷受水温影响较大。     

河流污染物通量估算方法筛选及误差分析

准确估算污染物通量对河流污染物总量控制和水质保护具有重要意义,但常规监测方法通常不能进行连续采样,数据相对比较稀缺,因此,选择恰当的采样间隔和通量估算方法,并对方法可能带来的误差进行估算,对提高通量估算的可靠性具有十分重要的意义.基于此,以江西赣江滁槎水质自动站2005—2007年3个水文年的水量和水质资料为基础,采用Monte Carlo方法模拟时间间隔分别为2、3、5、6、10、15和30 d的河流水质离散采样方案,并计算每种采样方案下的通量.同时,采用偏差(系统误差)和不精确度(离散程度)两个指标,比较了A、B、C、D、E 5种常规通量计算方法的误差分布,并建立了各算法误差随时间间隔变化的相关性曲线,以对河流污染物通量估算方法进行筛选.研究表明,滁槎断面COD_Mn采用瞬时值C_i与时段平均流量 Q_p乘积的方法计算年通量更准确;而NH₄⁺-N由于瞬时通量与流量相关性不显著,采用时段瞬时通量平均计算年通量更准确.     

硅藻土混凝剂在污染河水处理中的应用研究

以改性硅藻土为混疑剂，对具有不同污染特征的苏州河各支流污染水体进行了化学强化一级处理试验研究。结果表明，硅藻土混疑剂的最佳投药量随原水水质的不同而不同；硅藻土对C0Dcr和P有较高的去除效率，而对NH3-N的去除率不高；不同污染河水水质对硅藻土的混疑效果有比较显著的影响，表现为在混疑剂的最佳投药量条件下，C0Dcr去除量与原水CODcr之间存在着显著的线性关系。     

小流域生态经济型水土保持综合治理研究

文中介绍了根据辽东山区生态环境和自然资源特点，以市场规律为指导，在水土保持生态环境建设中，将小流域水土流失防治与资源开发紧密结合起来，促进了流域生态经济同步发展的经验，进而探讨了小流域治理生态经济良性循环可持续发展有效途径     

锡林河上游雨季降水、河水和地下水转化关系

为深入理解草原内陆河流域的水文循环过程及不同水体转化机制,以锡林河流域大气降水、河水和地下水为研究对象,对其氢氧稳定同位素进行了测试及多尺度时空特征分析,探究流域不同水体间的定量转化关系.结果表明：①锡林河流域具有明显的内陆性半干旱气候特征,大气降水是流域河水和地下水的主要补给源,地下水和河水同时经历了不同程度的非平衡蒸发;②河水同位素组成在季节上表现出春秋贫化、夏季富集的特征,在空间上表现为自上游到下游逐渐升高的趋势;浅层和深层地下水δ¹⁸O在生长季的波动变化基本一致,二者的主要差异发生在生长季末期,即前者趋于稳定而后者呈上升趋势,反映出深层地下水对大气降水和地表水入渗补给具有滞后响应,在空间上二者均由东南向西北逐渐贫化;③基于端元混合模型的估算结果可知,夏季大气降水和浅层地下水对河水的平均补给比例分别为52.69%和47.31%,说明对于内陆河流域,即使在多雨季节,浅层地下水也是河水的重要补给来源,研究旨在为半干旱典型草原内陆河流域的水资源调控和生态环境保护提供理论指导.