Variability of Raindrop Size Distribution during a Regional Freezing Rain Event in the Jianghan Plain of Central China

The characteristics of the raindrop size distribution(DSD)during regional freezing rain(FR)events that occur throughout the phase change(from liquid to solid)are poorly understood due to limited observations.We investigate the evolution of microphysical parameters and the key formation mechanisms of regional FR using the DSDs from five disdrometer sites in January 2018 in the Jianghan Plain(JHP)of Central China.FR is identified via the size and velocity distribution measured from a disdrometer,the discrete Fréchet distancemethod,surface temperature,human observations,and sounding data.With the persistence of precipitation,the emergence of graupel or snowflakes significantly reduces the proportion of FR.The enhancement of this regional FR event is mainly dominated by the increase in the number concentration of raindrops but weakly affected by the diameters.To improve the accuracy of quantitative precipitation estimation for the FR event,a modified second-degree polynomial relation between the shapeμand slopeΛof gamma DSDs is derived,and a new Z-R(radar reflectivity to rain rate)relationship is developed.The mean values of mass-weighted mean diameters(D_(m))and generalized intercepts(lgN_(w))in FR are close to the stratiform results in the northern region of China.Both the melting of tiny-rimed graupels and large-dry snowflakes are a response to the formation of this regional FR process in the JHP,dominated by the joint influence of the physical mechanism of warm rain,vapor deposition,and aggregation/riming coupled with the effect of weak convective motion in some periods.

Conversion relationship of rainfall-soil moisture-groundwater in Quaternary thick cohesive soil in Jianghan Plain,Hubei Province,China

The scientific field test site of rainfall-soil moisture-groundwater conversion in Dabie Mountain Area–Jianghan Plain is located in the northern region of the Jianghan Plain,the transition zone between the Dabie Mountain Area and Jianghan Plain.It’s a great field test site to study the material and energy exchange among rainfall,soil moisture,and groundwater of the Earth’s critical zone in subtropical monsoon climate plain areas.This paper analyzed the connection between rainfall and volume water content(VWC)of soil at different depths of several soil profiles,and the dynamic feature of groundwater was discussed,which reveals the rainfall infiltration recharge of Quaternary Upper Pleistocene strata.The results show that the Quaternary Upper Pleistocene aquifer groundwater accepts a little direct rainfall recharge,while the lateral recharge is the main supplement source.There were 75 effective rainfall events among 120 rainfall events during the monitoring period,with an accumulated amount of 672.9 mm,and the percentages of effective rainfall amount and duration time were 62.50%and 91.56%,respectively.The max evaporation depth at the upper part in Quaternary cohesive soil was no less than 1.4 m.The soil profile was divided into four zones:(1)The sensitive zone of rainfall infiltration within 1.4 m,where the material and energy exchange frequently near the interface between atmosphere and soil;(2)the buffer zone of rainfall infiltration between 1.4 m and 3.5 m;(3)the migration zone of rainfall infiltration between 3.5 m and 5.0 m;and(4)the rainfall infiltration and groundwater level co-influenced zone below 5.0 m.The results revealed the reaction of soil moisture and groundwater to rainfall in the area covered by cohesive soil under humid climate in Earth’s critical zone,which is of great theoretical and practical significance for groundwater resources evaluation and development,groundwater environmental protection,ecological environmental improvement,drought disaster prevention,and flood disaster prevention in subtropical monsoon climate plain areas.

The Agricultural Assessment of Climatic Resource and Modeling in Jianghan Plain-Lake District

The feature of the climatic resource and the agricultural assessment in Jianghan plain lake district are discussed. In order to exploit the climatic resource, we have recommended some three dimensional agriculture development models in this region according to the types of land use, such as paddy field ecological zone, dry land ecological zone, outskirts ecological zone of the city, waterbody ecological zone, woodland ecological zone.

Hydrocarbon Accumulation Process in the Marine Strata in Jianghan Plain Area, Middle China

Marine strata in the Jianghan Plain area are widely distributed with a total depth of more than 8,000 m from the Upper Sinian to the Middle Triassic. Six reservoir caprock units, named Z-C2, C2-O, S, D--C, P and T1, can be identified with each epoch. The geology, stratigraphy, drilling, oil testing and other basic data as well as the measured inclusion and strontium isotope data in the study area are used in the analysis of the formation and evolution process of marine petroliferous reservoirs in the Jianghan Plain area. This study aims to provide a scientific basis for the further exploration of hydrocarbons in the Jianghan Plain and reduce the risks by analyzing the key factors for hydrocarbon accumulation in the marine strata. Our findings show that in the Lower Palaeozoic hydrocarbon reservoir, oil/gas migration and accumulation chiefly occurred in the early period of the Early Yanshanian, and the hydrocarbon reservoir was destroyed in the middle-late period of the Early Yanshanian. In the Lower Triassic-Carboniferous hydrocarbon reservoir, oil/gas migration and accumulation chiefly occurred in the Early Yanshanian, and the hydrocarbon reservoir suffered destruction from the Late Yanshanian to the Early Himalayanian. The preservation conditions of the marine strata in the Jianghan Plain area have been improved since the Late Himalayanian. However, because all source beds have missed the oil/gas generation fastigium and lost the capacity to generate secondary hydrocarbon, no reaccumulation of hydrocarbons can be detected in the study area＇s marine strata. No industrially exploitable oil/gas reservoir has been discovered in the marine strata of Jianghan Plain area since exploration began in 1958. This study confirms that petroliferous reservoirs in the marine strata have been completely destroyed, and that poor preservation conditions are the primary factor leading to unsuccessful hydrocarbon exploration. It is safely concluded that hydrocarbon exploration in the marine strata of the study area is quite risky.

Wetland Ecosystem Function Assessment and The Sustainable Development in Jianghan Plain- Lake District of China

Wetlands in Jianghan plain lake district fulfill many uses and functions related to hydrology, waste assimilation, ecosystem productivity and bio diversity. But human incorrect activities generally result in significant negative impacts on number, biodiversity, and functioning of wetlands. In order to put wetland resources to rational use and protect wetland ecological environment, some effective measures should be taken.

APPLICATION OF ANALYTIC HIERARCHY PROCESS TO ASSESSING THE ECOLOGICAL VULNERABILITY OF WETLANDS IN THE JIANGHAN PLAIN

Wetlands in the Jianghan Plain are important components of wetland types in lake area in the middle and lower reaches the Changjiang (Yangtze) River and they fulfill many uses and functions related to hydrology, waste assimilation, ecosystem productivity and biodiversity. Owing to natural factors and human activities, especially excessive reclamation from lakes, the shrinking process of the lakes has been accelerated. Wetland ecosystem has shown the characteristics of vulnerability. According to the analysis of wetland ecological function in the Jianghan Plain, this paper presented an index system related to productivity, stability and environmental capacity. By using the method of Analytic Hierarchy Process, we computed the values of the relative weights of the indexes, and evaluated the vulnerability level of the wetland ecosystem by the method of multi-indexes. The case study showed that the fragile extent of wetland ecosystem in the Jianghan Plain is 5.6. This means that the wetland ecosystem in the Jianghan Plain is laid to the state of middle vulnerability. Therefore, the wetland conservation and eco-rehabilitation in the Jianghan Plain should be paid attention to.

THE SIMULATED STORAGE CAPACITY OF FLOOD AND WATERLOGGING IN THE TYPICAL AGRICULTURAL REGION IN JIANGHAN PLAIN

The Jianghan plain is one of the important bases of China’s agricultural productivity,located in central and southern Hubei province in the mi ddle reach of Yangtze River.The Jian ghan Plain is the one region of flood a nd waterlog-ging occurring frequently.The area is low-lying and is characterized by deep alluvial deposits,many smalle r rivers and numerous larger and shallow lakes fo rmed by meandering of the Changjiang(Yangtze)River.The alluvial plain is a honey-comb of waterways bordered by natura l levees,and the depressional areas encompassed by these waterways are dish-shaped in cross-section.The s ystems of rivers and lakes are main we tland types in this area.Owing to wetlands in Jianghan plain-lake district fulfill the function related to the flood r egulation,the estimating of the sto rage capacity is use-ful to controlling and reducing the d isasters of flooding and waterlogging.In this paper,by selecting typic al experimental area,based on its DEM,the relation a mong the water level,area and volume of inundation in the typical region i s de-fined by using regression analysis.Based on the agricultural cultivating line in this region and the experim ent result of bear-ing the inundation for crop,we defin e the storage capacity of the typical region in Jianghan Plain -Lake distr ict.

Dynamic Analysis of Land Cover in Four-Lake Area of Jianghan Plain Based on MODIS-EVI Time Series Data

According to the time series data of Enhanced Vegetation Index (EVI) in Four-Lake Area of Jianghan Plain during the period 2001-2007, we use Harmonic Analysis of Time Series (HANTS) to conduct cloud removing processing, and calculate the sum of square N of time series value of each pixel. The pixels with N>0.25 are classified as vegetation coverage area; the pixels with N<0.25 are classified as non-vegetation coverage area. As to vegetation coverage area, we use the second-order difference method to judge the frequency of peak value of EVI time series data. Within one year, the vegetation coverage area with peak value happening 1 time is woodland and grassland; the vegetation coverage area with peak value happening 2 times is arable land; the vegetation coverage area with peak value happening 3 times or more is vegetable land. Supervised classification method is used to identify cities, towns, water area in non-vegetation coverage area and woodland, grassland in vegetation coverage area. We draw the land cover classification diagram of Four-Lake Area in the period 2001-2007. In comparison with the land cover classification based on multitemporal ETM data in 2001, the difference of area of arable land is within 10%. Using MODIS-EVI data, we can rapidly and efficiently conduct land cover classification with low cost. The dynamic analysis results indicate that the area of arable land is in the process of declining, while the area of other cover types shows an increasing trend.

Spatial-Temporal Evolution Characteristics and Driving Factors of Agricultural Space in Jianghan Plain from the Perspective of “Three-Zone Space”

Studying the agricultural spatial distribution characteristics of Jianghan Plain from 2000 to 2018 and its spatial-temporal transformation with ecological space and urban space is of great significance for optimizing the spatial structure of the country, enhancing the supply capacity of agricultural products, and ensuring food security. The research results show that during the period from 2000 to 2018, the agricultural spatial concentration in the area along the “Xiaogan-Jingzhou” link was relatively high, and the areas with large declines were mainly distributed in the flat areas between the Yangtze River and Han River;the space is continuously reduced by the occupation of ecological space and urban space, and ecological space and urban space have been improved respectively;agricultural space has been transformed into ecological space, and the largest urban space has been transformed. Ecological space has been transformed into agricultural space and urban space. Less urban space has been transformed into agricultural space and ecological space.

Environmental Isotopes and Cl/Br Ratios Evidences for Delineating Arsenic Mobilization in Aquifer System of the Jianghan Plain,Central China

Environment isotopes(δ18O andδ2H)and Cl/Br ratios in surface water and groundwater are combined to investigate arsenic mobilization in aquifer system of the Jianghan Plain.The groundwater has relatively high arsenic concentrations,ranging from 3.6 to 1055.3μg/L with an average of 102.2μg/L,which exceeds China’s drinking water standard(10μg/L).The arsenic content of surface water samples is quite low with the range of 6.0–14.3μg/L,averaging 9.5μg/L.δ18O andδ2H values for surface water and groundwater samples plot close to the local meteoric water line(LMWL),reflecting their meteoric origin;a subset of the samples(shallow wells,10 m)shows a shift to LMWL,commensurate with mixing with surface water and evaporation.The correlations betweenδ18O values and Cl concentration and Cl/Br ratios as well as arsenic concentration demonstrated that surface water and groundwater interactions,including active exchange between river/pond water and groundwater and vertical infiltration from agricultural and aquacultural soils,were dominated processes affecting arsenic mobilization in shallow groundwater system and lateral recharge was the main process controlling arsenic behavior in deep groundwater system.The results of this study will be beneficial to understanding the causes of arsenic mobilization in Jianghan groundwaters at different depths.

Detrital Zircon Geochronology and Provenance of Core Sediments in Zhoulao Town,Jianghan Plain,China

In our study,the U-Pb age spectrum of detrital zircons from terrigenous sediments is used to determine the sources.The Middle and Upper Reaches of the Yangtze River drain the western Yangtze craton and eastern Tibetan plateau,and take lots of sediments to the Jianghan （江汉） plain.Detrital zircons collected from Zhoulao （周老） core provide an ideal sample for the provenance studies.Here we report LA-ICP-MS U-Pb ages of 125 detrital zircons from one sand sample in the core sediments,which is recovered from a depth of 86.76-88.58 m and the paleomagnetic age is about 800 kaBP,in Zhoulao Town.The 125 zircons reveal nine major age peaks of 3.0,2.5-2.3,2.0-1.7 Ga,838-723,453-415,257,212,166 and 17 Ma.Only two zircons have ages of 14.8 and 16.5 Ma,their appearance indicates that the headwater of the Yangtze River had reached the Tibetan plateau about 800 ka ago.Our results also show that the Hanjiang （汉江） River did not influence the sediments of the Zhoulao core obviously at that time.

Wetland changes in Jianghan Plain and simulation with GIS

Wetland plays an important role in the tempo spatial evolution of climate, biogeochemistry and biodiversity of the terrestrial ecosystems of the earth. To trace the patterns of wetland changes in the past and predict the changing trends in the future in the dimension of human activities is an arduous task for geographers and ecologists. The paper describes how to combine GIS with geo informatics and geography to simulate the wetland changes happened in Jianghan Plain in the middle reaches of the Yantze River in the last 40 years, and presents the results. The environmental implications of the wetland changes are discussed.

Magnetism parameters characteristics of drilling deposits in Jianghan Plain and indication for forming of the Yangtze River Three Gorges

The forming time of the Yangtze River Three Gorges is considered as one of keys in the research on the Yangtze River,also is one of the most disputed hotspots.In order to solve the difficult problem,the authors adopt the internationally recognized thoughts and methods of substance tracing from source to sink.The lithologic characteristics,magnetic parameters and magnetic mineral characteristics of deposits in 2 bores are analyzed,which are both sampled from the sedimentary center of the Jianghan Plain.The results are as follows:At about 110 m depth of the core,the contents of coarse materials and stable magnetic mineral both increase significantly.Meanwhile,the magnetic susceptibility of sediment,saturation isothermal remanent magnetization and magnetic susceptibility values of anhysteretic remanent magnetism increase suddenly,which all reflect that at about 110 m depth,the important adjustment has appeared in water system of the Jianghan Plain,and the sedimentary environment and material composition have changed greatly.And it may be the horizon where the Yangtze River Three Gorges formed,its forming time reflected by the paleomagnetic dating is between 1.17 and 1.12Ma B.P.

THE DEVELOPMENT AND PROTECTION OF WETLANDS IN THE FOUR LAKE AREA OF JIANGHAN PLAIN

This paper summaries the ecological and environmental research works in the Four Lake Area. A great deal of research and developing works have been done, which may be concluded into three kinds of models for a agricultural development. They are Model Ⅰ-d

供需评价异化视角下农业生产托管服务价格形成机制存在的问题——来自江汉平原的调查问卷

农业生产托管服务价格是影响托管服务供给和需求的重要因素。基于江汉平原农业生产托管服务供需双方对托管服务价格评价的调查结果,分析了农业生产托管服务价格形成机制的现状与存在的问题。结果表明,目前农业生产托管服务价格并不是供需双方一致达成的均衡价格,农业生产托管服务市场属于不完全市场,托管服务价格水平普遍偏高,供给方有让利给需求方的空间和动机,但存在供需错配问题,托管服务价格及补贴政策对供需的调节作用并没有得到充分发挥。为此,应完善供需沟通渠道,加强服务标准建设,大力发展新型农业经营方式,优化托管补贴对象,加强政策宣传和明确补贴指向,以促进农业生产托管服务价格形成机制的完善。

江汉平原乡村生态韧性时空分异及驱动因子研究

江汉平原自然环境优越,乡村生态韧性的提升是江汉平原全面推进乡村振兴、推动乡村高质量发展的关键.研究基于抵抗力、适应力、恢复力三维度构建了江汉平原乡村生态韧性指标体系,运用熵权TOPSIS法、核密度估计法、重心-标准差椭圆和地理探测器模型评估2005—2021年江汉平原乡村生态韧性水平,诊断时空演变特征,挖掘影响驱动因子.结果表明:1)在时序特征上,江汉平原乡村生态韧性水平呈现波动起伏的上升趋势,生态韧性差异逐渐减小.2)在空间分布上,江汉平原乡村生态韧性呈现“低值分散、高值集聚”的空间分布格局;空间上呈西南—东北走向,整体向西南推移.3)在影响因子上,地表起伏度、年平均降水量较常年变化率、归一化植被指数、环保占财政支出的比重是制约江汉平原乡村生态韧性的主要影响因子,并且影响因子由抵抗力向适应力和恢复力转变.研究结果能为江汉平原乡村生态保护和可持续发展提供技术支持.

基于物候信息图谱的耕地种植模式遥感监测方法

【目的】种植模式是作物种植的前后茬顺序的概括,反映耕地资源的利用方式和效率。本研究通过分析不同种植模式的物候特征,构建江汉平原地区的耕地物候信息图谱和种植模式谱,并实现该地区主要种植模式的提取。【方法】在地学信息图谱理论支持下,根据农作物种植的先验知识和不同种植模式所表现的物候差异,将植被指数变化过程和耕地利用方式的空间差异进行图谱合一的表达,组成包含耕地不同利用方式的耕地物候信息图谱;以江汉平原地区的主要种植模式为例,将关键物候期植被指数的状态进行排列组合,建立植被指数状态到种植模式的信息重映射规则,并在此基础上根据农作物特有的物候知识进行物候特征挖掘,进行江汉平原地区种植模式谱的构建;进而利用朴素贝叶斯网络融合关键物候期影像和物候知识实现江汉平原种植模式的提取。采用基于知识概率编码的方法,对关键物候期的植被指数状态进行定量表达。【结果】构建了江汉平原地区的种植模式谱,发现江汉平原地区的种植模式谱由8种种植模式构成:春单季、夏单季、春夏双季、夏秋双季、双季稻、经济作物、鱼塘、苗木或撂荒。提出的种植模式谱及基于朴素贝叶斯网络的种植模式提取方法能够准确地提取出所有种植模式,并具有良好的精度和适用性。江汉平原地区在研究时段内呈现显著的夏秋双季扩张,以及春夏双季和夏单季减少的趋势。【结论】种植模式谱全面反映了江汉平原地区种植模式的总体特征,提升了耕地利用方式监测的准确度,丰富了耕地资源利用方式的内涵。本文方法得到的种植模式分布图可以作为作物制图的基础底图数据,也是种植强度制图的重要依据。

多维城市化与乡村地域功能演化的时空关联研究:以江汉平原为例

探索城市化与乡村地域功能演化的复杂性关联规律既是新时期城乡融合与乡村振兴的重要命题,也是乡村地理学研究的时代前沿。以江汉平原为研究案例,以2000—2019年为研究时段,在建立城市化指标体系和乡村地域功能评价模型的基础上,运用系统动态面板模型、时空地理加权回归模型等方法,深入探究多维城市化与乡村地域功能之间的时序关联规律及空间关联特征。结果表明:(1)江汉平原乡村地域功能演化具有明显结构分异性,其中,乡村地域综合功能在时序上呈现阶段性变化,空间上呈现沿焦柳-长荆发展轴的倒“U”形分布格局向汉宜线-东部平原带的“T”形分布格局演化。(2)江汉平原多维城市化与乡村地域功能在时序关联上呈现复杂性特征,其中人口、经济城市化与乡村地域综合功能呈现“N”形曲线规律,土地城市化与乡村地域综合功能呈现单调递增态势,但弹性系数值低于后期人口和经济城市化正效应值。(3)江汉平原多维城市化与乡村地域功能在空间关联上呈现明显规律性和异质性特征。研究结果有利于丰富乡村地理学理论内涵,为案例地区的城乡融合与乡村振兴实践提供支持。

平原河网区生态流量阈值研究——以江汉平原典型河流为例

生态流量是维系江河湖泊水生态系统的重要保障,而平原河网区水系错综复杂,传统生态流量计算方法适用性较差,开展平原河网区的河流生态流量阈值研究具有重要意义。以湖北省江汉平原典型河流为研究对象,从基本生态、特殊生境以及水环境保护等方面开展平原河网区的生态流量阈值研究,以多样化、动态化的需水过程定义生态流量阈值,结果与实际相符,研究成果可为平原河网区生态流量阈值的确定及应用提供借鉴。

近代江汉平原粮棉种植空间变动特征分析(1861—1949)

江汉平原粮食生产以稻米为主,其长期保持优势地位,并一直延续至近代。随着中外经济形势变动,在港口-腹地因素推动下,棉花种植比例逐渐提升,作物种植的空间分工日益凸显。通过对江汉平原作物种植变迁的研究发现,小农所处的地理环境决定了其种植选择,工业发展刺激了作物的种植扩张,港口区位条件限制了地区经济结构的升级。以此为基础,对经济理性与生存理性问题、近代经济发展动力问题以及内陆与沿海的发展路径问题进行解释。