Analysis of Flood Risks Upstream from the Imboulou Hydroelectric Dam on the Léfini River, a Tributary of the Right Bank of the Congo River

The analysis of the risk of flooding upstream from the Imboulou hydroelectric dam on the Léfini River in the Republic of Congo-Brazzaville, focused on the evolution of annual rainfall and flow in the study area during the period from 1970 to 2020 before and after the building of the dam in 2005, by applying statistical methods. These methods were used to analyse the spatial and temporal evolution of rainfall and flow at the unique hydrometric station located at the RN2 (National Road N°2) bridge in the village of Mbouambé in the Pool region. This work has shown that rainfall is not the cause of flooding in the Léfini catchment area. The monthly flow coefficient (MFC) showed exceptional flooding from November and December onwards after the dam was built, resulting in a variability of flows, with periods of high and low water. In addition, the annual average flow (AAF) and the maximum average flow (MAF) increased after the dam was built. Maximum average flows (MAF) were higher than annual average flows (AAF) throughout the period of study (1970-2020). The annual and monthly rainfall-runoff relationship showed changes after the dam was built, particularly from 2009 and during the months of November and December. .

Evolution of Main Characteristics of the Registered Cotton Cultivars in National Cotton Regional Trials in Yangtze River Valley

[Objective] The aim of this study was to characterize the national regis- tered varieties selected from cotton regional trials in Yangtze River Valley （YaRV） in recent years. [Method] Cotton cultivar classification and comprehensive evaluation index were set up based on national cotton registration standard. GGE biplot method was adopted to analyze the correlation of major breeding target characters of 53 national registered cotton varieties in cotton regional trials in YaRV during 1981-2012. According to the shift of check cultivars in cotton regional trials in the past, the cotton regional trial practice since 1981 was divided into five periods. The dynamic of cultivar type＇s proportion and the evaluation index scores was analyzed across the five periods. [Result] There existed intricate interrelationship among cotton breeding target traits, which constrained it necessary to construct indices for com- prehensive evaluation of cotton varieties. The dynamic of cultivar types in the five periods indicated that type II varieties emerged since Simian 3 period and then its proportion decreased gradually; type Ⅲ varieties maintained a certain proportion in each period and kept on the rise overall; type Ⅳvarieties occupied the majority pro- portion of registered cultivars before 1993, but a minor proportion since Simian 3 period. On the other side, the change trend of the evaluation index demonstrated that the varieties registered before 2003 did not pass the qualified line at present. The peak scores appeared in the varieties registered during 2004-2008. The scores of the varieties registered after 2009 were only slightly over the qualified line. [Conclusion] More attention should be paid to the improvement and evaluation of micronaire, so as to guide the simultaneous development of high yielding and fiber quality in cotton breeding and registration procedure in YaRV.

Development and Validation of National Cotton Cultivar Registration Index Model in Yangtze River Valley

[Objective] Based on the cotton variety high yielding potential, fiber quality traits, disease resistance, and early maturity characters, a cultivar registration index model was developed to simplify the tedious calculation process in national cotton registration procedure, and thus to enhance the practical application of cultivar regis- tration index in cotton breeding ancl cotton recommending. [Method] By means of correlation analysis, partial correlation analysis and path analysis methods, the cor- relation of cotton main properties and their effects on cultivar registration index were explored using the dataset of national cotton regional trials in Yangtze River Valley during 1996-2013. The cultivar registration index model was constructed with step- wise regression statistical technique to ascertain the quantitative relationship of main characters with cultivar registration index, and the regional cotton trial dataset in 2013 was used to validate the model. [Result] Several characters with larger deter- minants to cultivar registration index were screened out,ie. lint yield increase ratio, pro-frost yield ratio, verticillium wilt index, fiber strength, fusarium wilt index and mi- cronaire value. The cultivar registration index model defined the functional relation- ship of cultivar registration index with the selected main characters, among which lint yield increase ratio, fiber strength and micronaire value contributed most to culti- var registration index. The model validation with regional cotton trials in 2013 indi- cated the root mean square error, RMSE was only 2.77, and the variation coeffi- cient was 6.77%, which confirmed the model prediction effect was quite perfect. [Conclusion] The developed cultivar registration index model was reliable enough to simulate the complicated scoring system in cultivar registration procedure, also sim- plified cotton registration process, and enhanced the practicability of the cultivar reg- istration index.

Evaluation on the High Yielding, Stability and Comprehensive Performances of Check Cultivars in National Cotton Regional Trials in the Yangtze River Valley

[Objective] This study was to analyze the high yielding, stability, adaptabil-ity and main characteristics of check cultivars in national cotton regional trials in the Yangtze River Val ey in 2000-2013, with the aim to provide theoretical basis for the reasonable selection of check cultivars for cotton regional trials. [Method] GGE biplot analysis method was used to carry out the intensive analysis and comprehensive comparisons on the performances and differences of the 9 major characters of check cultivars, namely, lint cotton yield , stability, and other main traits including bol weight, bol number, lint percentage, fiber length, fiber strength, micronaire val-ue, plant height and seed index. [Result] Ezamian 10 was suitable in the majority of cotton planting regions in the Yangtze River Val ey, with the best high yielding abili-ty and perfect yield stability. The yielding ability of Xiangzamian 8 ranked the sec-ond, but its stability was the poorest. Xiangzamian 8 was of the specific adaptive cultivar with relatively good performance in high yielding but the poorest stability. The suitable planting areas of Xiangzamian 8 were limited to the cotton planting re-gion around Dongting Lake in Hunan province, Poyang Lake in Jiangxi Province, the Coastal region in Jiangsu Province and Wuhan district in Hubei Province. Xi-angzamian 2 performanced poorer in both yielding and stability, while Simian 3 ranked first in stability but the last in yielding ability. The dominant character of Xi-angzamian 8 and Xiangzamian 2 were high cotton plants and big bol s. Simian 3 performanced super in lint percentage and fiber length. Ezamian 10 was strong in cotton bol formation ability, lint cotton yielding, fiber strength and seed size, as wel as high micronaire value. [Conclusion] The outstanding performance of Ezamian 10 in high and stable yield in the Yangtze River Val ey in recent years has effectively promoted the high yielding ability of candidate varieties in cotton regional trials in the area.

Evolution of Nitrogen, Phosphorus and Potassium Fertilizer Application Rates in Cotton Fields and Its Influences on Cotton Yield in the Yangtze River Valley

[Objective] The historical evolution pattern of nitrogen （N）, phosphorus （P） and potassium （K） fertilizer application rate and its effects on lint cotton yield were explored to provide the theoretical basis for reasonable fertilizer management strate-gy in the cotton planting region of the Yangtze River Val ey. [Method] GGE biplot analysis method was adopted to analyze the correlation among N, P and K fertilizer application rate and lint cotton yield with the dataset of national cotton regional trials of the Yangtze River Val ey during 1991-2013. The linear and nonlinear regression analysis method was used to reveal the evolution of the fertilizer applying patterns, and analyze the effects of N, P, K application rates on cotton lint yield. [Result] The application rates of N, P and K fertilizer presented highly significant positive corre-lation with lint cotton yield, among which the potassium fertilizer was the strongest relative factor with lint cotton yield, fol owed by phosphorus fertilizer, while nitrogen fertilizer was the weakest factor. The application rate of nitrogen fertilizer was relat-ed with the test year in the pattern of a quadratic function, while phosphate and potassium had progressive increase linear relation with the test year in the cotton planting region of the Yangtze River Val ey. Meanwhile, cotton lint yield was in re-sponse to nitrogen fertilizer content increase with a quadratic parabola function, and increased with the applying phosphate fertilizer and potassium fertilizer content with linearly increasing function. [Conclusion] The increasing application amount of N, P and K fertilizer was general y beneficial to cotton yield improvements, however, ex-orbitant applying nitrogen fertilizer was unfavorable for cotton production, and a reasonable mixture formula of N, P and K fertilizer was better in terms of cotton yield-increasing effect.

沿黄灌区不同种植密度对胡麻产量和植株性状的效应

为探索胡麻产量和植株性状对种植密度的响应规律,筛选适宜白银市灌区胡麻的种植密度。以陇亚13号为供试品种,研究不同种植密度(600万、750万、900万、1050万、1200万粒/hm^(2))对胡麻产量和植株性状的影响。结果表明,随着种植密度的增加,胡麻产量、株高、工艺长度、单株生物量、单株粒重、每果粒数和经济系数呈先增后降的趋势,分茎数、分枝数、分枝长、果层厚度、单株果数和千粒重逐渐降低,主茎贡献率增加,分茎贡献率逐渐降低。在白银市灌区现阶段生产水平下,胡麻种植密度为750万粒/hm^(2)时,产量水平最高,为2299.68kg/hm^(2)。

基于分布式水文模型的水源涵养不同功能评估方法——以渭河涵养区为例

为了实现水源涵养量计算和不同功能的综合评估,基于分布式水文模型(WEP-L)提出了一种新方法,即利用WEP-L模型计算次降水过程中降水量和地表产流、冠层截留量的差值作为水源涵养量,并分别评估削洪(地表径流量)、补枯(地下径流量)、维持植被生态系统用水(植被蒸腾量)等不同水源涵养功能的评估方法。为了验证该方法的合理性,以渭河流域咸阳站以上区域为例,对比了该方法和InVEST模型方法的计算结果,由于两种方法在评估内容和使用模型上都存在差异,为了保证计算结果的可比性,先对比了基于相同评价内容的WEP-L模型法I和InVEST模型方法,再对比了基于不同评价内容的WEP-L模型法I和WEP-L模型法II,结论如下:基于相同评价内容的WEP模型法I和InVEST模型法计算结果数值接近,研究区2000—2018年水源涵养量年均值分别为12.43 mm(5.76亿m~3)和12.08 mm(5.6亿m~3),两种方法所得结果空间分布特征相似,稍有差异之处与InVEST模型的参数没有经过本地化处理有关;基于不同评价内容的WEP-L模型法Ⅰ和WEP-L模型法II计算结果数值相差较大,研究区2000—2018年水源涵养量均值分别为12.43 mm和432.57 mm,空间分布特征上有差异的地方分布于研究区的北部、东部及东北部,主要与两种方法评价时是否考虑蒸散发有关。WEP-L模型法II评估结果中削洪、补枯、维持植被生态系统用水等功能多年变化趋势分别为:2006—2010年期间增加、2012年以后下降以及增加。2012年后补枯功能和维持植被生态系统用水功能之间可能存在权衡关系。通过不同方法计算结果差异原因分析,证明了基于WEP-L模型的不同涵养功能评估方法的合理性,其结果也可为渭河涵养区水资源和生态保护策略的制定提供更多依据。

不同有机改良剂对盐碱地菊芋产量及土壤理化性质的影响

试验在黄河三角洲典型盐碱地上进行,以菊芋品种南芋1号为供试材料,设置不施肥对照(CK)、常规施肥(F)、商品有机肥(M)、生物炭基调理剂(T1)、抗盐调理剂(T2)共5个处理,研究不同有机改良剂对菊芋苗期生物量、块茎产量及土壤主要理化性质的影响。结果表明:施用有机改良剂对盐碱地菊芋苗期干物质量和成熟期地下块茎产量影响显著,其中T1处理菊芋苗期干物质量和成熟期块茎产量最高,较CK、F处理分别显著提高76.4%、36.2%和38.7%、25.1%。与CK相比,T1处理菊芋苗期0~30 cm土层土壤pH值显著下降;M、T1和T2处理较CK和F处理显著降低菊芋苗期0~20 cm土层土壤水溶性盐含量,降幅达8.3%以上,且T1优于M和T2处理;菊芋收获后,M、T1和T2处理0~10 cm土层土壤有机质含量较CK分别显著提高15.1%、20.7%和21.0%,T1处理显著增加0~20 cm土层土壤碱解氮、有效磷和速效钾含量,M处理显著增加0~20 cm土层土壤有效磷和速效钾含量。综上,施用生物炭基调理剂对改良土壤盐碱化、促进壮苗培育、提高菊芋产量效果较优。

Cd污染河道底泥修复植物优选

选用12种植物对上海市某Cd污染黑臭河道底泥进行了修复试验研究,考察了修复植物对Cd污染底泥的耐受性、富集转运特性和修复效果,以期为实际开展植物修复Cd污染河道底泥研究提供科学依据.结果表明:除移植的灯芯草(Juncus effusus L.)生长情况较差外,其余11种植物对试验底泥均有良好的耐受性;龙葵(Solanum nigrum L.)、灯芯草、金盏菊(Calendula officinalis L.)、八宝景天(Hylotelephium erythrostictum(Miq.)H.Ohba)以及大吴风草(Farfugrium japonicum(L.f.)Kitam.)地上部分的Cd质量比均高于4.50 mg/kg;苘麻(Abutilon theophrasti Medicus)、灯芯草、金盏菊、八宝景天、大吴风草以及美洲商陆(Phytolacca americana L.)对Cd的富集系数(bioaccumulation factor,BCF)与转运系数(translocation factor,TF)均大于1;龙葵、金盏菊、美洲商陆以及三叶鬼针草(Bidens pilosa L.)对Cd的提取量均高于0.30 kg/hm^(2),具有较好的修复效果,其中龙葵对试验底泥中Cd的提取量为2.84 kg/hm^(2),提取效率可达88.75%,展现出了较大的修复潜力.优选试验结果证明,龙葵可作为该地区Cd污染河道底泥的最佳修复植物.

金沙江干热区麻疯树(Jatropha curcas L.)杂交育种技术的初步研究

对金沙江干热区麻疯树生物特性、开花特性、结实特性进行观测,并开展不同地理种源麻疯树杂交育种试验。结果表明,麻疯树在本区域生长发育较好,可持续开花结果至1月初,雌雄花比例可达1∶10左右。通过麻疯树杂交育种试验,研究了麻疯树雌雄花分辨、雌花可授粉时间、套袋材料及去袋时间等特性。通过对金沙江干热区麻疯树主要特性和杂交育种技术试验研究,有利于提高育种效果,加速育种进程,提高育种工作的预见性。

基于L-THIA模型的温榆河流域非点源污染负荷变化分析

为研究温榆河流域城市化过程中土地利用变化对非点源污染负荷的影响,基于GIS(地理信息系统)和RS(遥感),利用二次开发改进后的长期水文影响评价(L-THIA)模型,采用实地测得的EMC(事件平均浓度)数据,模拟了1992年和2009年非点源污染负荷量。结果表明,1992—2009年的城市化过程中商业用地、交通用地和住宅用地分别增加了13.95%、20.46%和85.76%,农业用地和水域分别减少40.04%和9.64%,导致非点源污染负荷量(总磷除外)明显增加。其中,总氮增加了3.31%,氨氮增加了12.20%,BOD5(5日生化需氧量)增加了11.87%,CODMn(化学需氧量)增加了7.62%,TOC(总有机碳)增加了15.46%,总磷下降了12.84%。交通用地、商业用地的非点源污染产出能力最强,应该成为非点源污染的重点控制区域。

L-肉碱对黄河鲤鱼生长性能和肌肉品质的影响

研究了饲料中添加不同水平(50、100及200 mg/kg)的L-肉碱对黄河鲤鱼生长性能和肌肉品质的影响。结果表明,在基础饲料中添加不同水平的L-肉碱均能在一定程度上降低饵料系数,显著提高肥满度(P<0.05),降低肝体比和脏体比(P<0.05),添加100 mg/kg的L-肉碱能显著提高黄河鲤鱼的增重率(P<0.05)。添加不同水平的L-肉碱均可以显著提高黄河鲤鱼体蛋白质和脂肪含量(P<0.05),改善肌肉氨基酸组成,能在一定程度上改善鱼体的肌肉品质。综合考虑L-肉碱对黄河鲤鱼生长性能和肌肉品质的影响以及经济效益,认为添加量以100 mg/kg较适宜。

长江中下游不同小麦品种淀粉特性及产量的差异性分析

为揭示长江中下游不同小麦(Triticum aestivum L.)品种的淀粉特性及产量间差异,寻找更适宜在该地区生长的优良小麦品种,对15个小麦品种的淀粉特性、沉淀值、蛋白质含量及产量进行分析。结果表明,各小麦品种间的淀粉糊化特性、淀粉冻融稳定性和淀粉含量差异较大,其中,宁麦9号和鄂麦006的糊化特性在一定程度上优于其他品种,且这2个品种的淀粉冻融稳定性表现较好、淀粉含量也较高。不同小麦品种间沉淀值存在显著差异,襄麦55和荆麦102沉淀值较高,分别为10.67 mL和8.00 mL。在15个品种中产量居前三位的依次为荆麦102、鄂麦596和漯麦6010,宁麦9号和鄂麦006产量居中。综上所述,荆麦102、鄂麦596和漯麦6010在长江中下游平原区种植可获得高产,而宁麦9号和鄂麦006在长江中下游平原区种植淀粉品质较优,故这些品种可以成为后续推广的优良品种。

L-矩法在澜沧江流域参数统计中的应用

水文频率分析计算中一般采用矩法作为参数估计方法,国内外许多研究及应用表明,矩法估计时有较大的估计偏差。L-矩是目前洪水频率分析计算的最新发展之一。它的最大特点是对洪水系列中的极大值和极小值远没有常规矩那么敏感,因而根据L-矩求得的洪水频率曲线参数的估计值比用常规矩所求得的值偏差小些。本文在澜沧江流域进行参数统计时运用了L-矩法,效果较好。

生物净化槽中菌群结构在梭鱼草(Pontederia cordata L)不同生长期的动态变化

为探究引入植物对生物净化槽处理黑臭河水的影响及机理，结合水质理化指标的动态变化，采用了ERIC—PCR指纹图谱技术来分析生物净化槽内的微生物群落结构在植物不同生长阶段的变化特征，比较植物与填料不同工艺组合对微生物群落结构的影响．结果发现：引种梭鱼草（Pontederia cordataL）的生物净化槽对主要污染物CODcr，NH3-N和TP的去除率分别提高了19．8％～69．4％，18．2％～68％和23．9％～77．2％；微生物群落结构随植物不同生长发育阶段而变化，分蘖期优势菌群的种类和数量最多，同期净化效果也最好；从三种工艺的运行效果来看，植物＋组合填料搭配最合适．

有限对称逆半群的L-断面

设In是有限集合Xn={1,2,...,n}上的有限对称逆半群.该文定义有限逆半群的L-断面,给出In的所有L-断面的构造和分类.

1959—2018年增江流域多时间尺度水源涵养变化特征

随着水资源短缺成为全球关注的焦点,水源涵养功能已成为流域生态系统最重要的服务功能之一和可持续发展的关键因素。然而,目前关于水源涵养功能的研究多集中于使用水源涵养的多年平均值,鲜有研究关注长序列水源涵养功能的多时间尺度变化规律。为此,文章以广州重要的水源区和生态屏障的增江流域为例,基于WEP-L分布式水文模型和水量平衡方程,分析了1959—2018年增江流域水源涵养年、月、日多时间尺度变化规律,探讨水源涵养的供给、调节和削峰补枯功能。结果表明:1959—2018年增江流域多年平均水源涵养685.7 mm,以-1.30 mm/a速率不显著减少;1959—2018年增江流域多年平均月水源涵养1—9月为正值,10—12月为负值,1、3、6、11和12月水源涵养呈不显著增加趋势,其他月份呈不显著减少趋势,变化趋势范围为-0.04~-0.67 mm/a;近60 a增江流域Max1day、Max3day、Max5day和Max7day为正值,而Min1day、Min3day、Min5day和Min7day为负值,除Min5day和Min7day的水源涵养不显著减少外,其他6个日极端水源涵养指标都呈不显著增加趋势;空间上,年尺度水源涵养变化呈东南和北部低,西南高的态势;1959—2018年增江流域年、月、日水源涵养分别体现其供给、调节、削峰补枯的功能;水源涵养与降水的相关性较大,且明显高于蒸散发和地表径流的相关系数,表明降水是水源涵养的最重要影响因素。

L形钢骨异形柱的ANSYS有限元分析

为研究L形钢骨混凝土异形柱的受力性能,对五个混凝土异形柱试件进行试验研究和采用ANSYS有限元软件进行数值模拟分析,计算得出了试件各材料的应力分布图和试件的极限承载力。将试验结果与有限元计算结果对比,表明二者显示了良好的一致性。结果表明,可以运用ANSYS有限元数值模拟技术对钢骨混凝土异形柱的受力性能进行深入研究,其模拟结果与实验现象吻合较好,说明了混凝土与钢骨、钢筋能够协同工作,并且试件随着含钢率的提高,其承载力增大。

基于L-THIA和GIS的辽河源头区小流域非点源污染负荷变化分析

农业非点源污染是导致流域水质恶化的重要原因之一。笔者选择了辽河源区域作为研究目标,重点研究辽河流域的小型水系,使用所处位置的土地状况以及日降雨量数据,基于长期水文影响评价模型L-THIA,以GIS空间分析技术为平台,对研究区的总氮、硝态氮、总磷、COD和可溶磷5种非点源污染物的污染输出负荷进行估算,并分析了其空间分布特征。结果表明:总氮、硝态氮和总磷3种污染物的单位网格污染物输出负荷的空间分布较为一致,可溶磷和COD污染输出负荷分布各有特点。区内的农用地域污染一般都是农田抑或是村里闲置的土地。经研究发现,越是干旱的区域会使得调查数据分布影响越大,对总氮、硝态氮和总磷的贡献率分别达到了82.57%、80.02%和92.92%,村镇用地对可溶磷的污染负荷分布影响最大,而水田对COD污染输出负荷作用明显。根据不同污染物输出负荷并结合土地利用现状,采用GIS空间叠加和融合技术,将研究区划分为4个非点源污染控制区,分区结果能够为非点源污染控制提供科学依据。

数字经济对黄河流域水资源利用效率的影响

为探究黄河流域数字经济与水资源利用效率之间的内在关联,基于2011—2019年黄河流域73个地级市的相关数据,利用超效率SBM模型测算各城市水资源利用效率,运用个体固定效应和中介效应模型,实证分析数字经济对黄河流域水资源利用效率的影响及作用机制。研究表明:数字经济发展能够显著提升黄河流域水资源利用效率,整体上呈现倒“U”型非线性影响关系;绿色技术创新在数字经济提升黄河流域水资源利用效率的过程中发挥中介作用。据此,建议适度发展数字经济,推动数字化和绿色化协同发展。