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.

Establishment and Application of Fertilization Model for Wheat Interplanted with Cotton in Jianghan Plain

3414 field experiment （including three nutrient elements at four gradient levels, a total of 14 unrepeated incomplete treatments） was designed to study the fertilization measures for wheat interplanted with cotton in Qianjiang City, Hubei Province. Fertilizer model for wheat interplanted with cotton in Jianghan Plain was finally established, based on which the soil nutrient indices in wheat-cotton inter- planting field were screened; and optimal nitrogen, phosphorus and potassium appli- cation for wheat was put forward as 130-210 kg/hm2 N, 40-70 kg/hm2 P2O5 and 40-60 kg/hm2 K2O.

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.

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.

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.

Is Larger Scale Better? Evidence from Rice Farming in Jianghan Plain

Small-scale household agricultural production has been in conflict with China＇s agricultural modernization.In the context of vigorously promoting rural land circulation and moderate scale management nationwide,research on the relationship between farm size and scale efficiency has become increasingly important.In this paper,we use the ＂DEA-OLS＂ two stage method to analyze data from 368 surveys of rice farming households in the Jianghan Plain.The scale efficiency of rice farming was calculated,and the relationship between farm size and scale efficiency investigated.The results indicate that（1） the rice farm size is generally small in Jianghan Plain,with an average of 0.77 ha.The average scale efficiency is 0.88,and it is the main factor limiting an increase in comprehensive technical efficiency.Moreover,88.32% of households are in the stage of increasing returns to scale.（2） There is a stable inverted ＂U＂ type relationship between rice farm size and scale efficiency.Considering characteristics of the householder,the household and land quality,the maximum scale efficiency corresponds to a household with 5 ha of rice farm.（3） Among householder characteristics,age has a significant negative influence on scale efficiency,and scale efficiency is lower for a household whose householder is engaged in non-farm work than for one whose householder is devoted to farming.As for land quality,there was a significant positive effect of irrigation on scale efficiency.Among family characteristics,the application of a machine during the seeding process increased scale efficiency by 3.07%.Therefore,we suggest that local government should actively promote rural land circulation,implement a staged-scale management subsidy,and other forms of support for the purchase of agricultural machinery and technical popularization.Increased investment in irrigation improvements and mechanical facilities and encouragement of farmers to enlarge their farm size could improve scale efficiency and farming profit and lead to the development of moderate scale management.

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。

江汉平原典型种植模式稻田土壤中农药残留特征

在江汉平原中稻-油菜/小麦轮作田、一季中稻田及再生稻田3种种植模式稻田采集土壤样品86个。调查了土壤样品中滴滴涕(DDTs,包括o,p′-DDT、p,p′-DDT、p,p′-DDE、p,p′-DDD)、六六六(HCHs,包括α-HCH、β-HCH、γ-HCH、δ-HCH)、甲胺磷、甲基对硫磷、氧乐果、乐果、敌敌畏、乙酰甲胺磷、毒死蜱、氯虫苯甲酰胺、吡蚜酮、吡虫啉、啶虫脒、三环唑、戊唑醇、氰氟草酯、二氯喹啉酸、乙草胺及异丙甲草胺等25种农药及其代谢产物的残留。结果表明,检出率最高的3种农药为当前常用杀虫剂氯虫苯甲酰胺(87.21%),杀菌剂三环唑(91.86%)及戊唑醇(72.09%),其残留均值分别为0.0397、0.0734 mg/kg及0.0276 mg/kg;已经禁用的有机氯农药滴滴涕(o,p′-DDT、p,p′-DDT、p,p′-DDE、p,p′-DDD)仍能检出,检出率为36.05%~66.28%。3种模式田块中检出的滴滴涕主要来源于历史上滴滴涕的使用。杀虫剂吡蚜酮及杀菌剂三环唑在再生稻田的残留量均值显著高于中稻-油菜/小麦轮作田及一季中稻田;但其他农药在不同种植模式稻田中的残留没有显著差异。本研究为江汉平原农药残留的治理及农药的合理使用提供了参考信息。

不同红椿家系苗期及幼林期在江汉平原的生长表现分析

【目的】红椿是湖北的重要乡土树种,但在江汉平原未有天然分布及人工栽培。选择出适宜于江汉平原地区发展的优良红椿家系,为该地区提供珍贵用材树种造林资源。【方法】以湖北恩施地区的17个红椿优树半同胞家系为研究材料,采用随机区组设计,在江汉平原石首市开展平茬后2 a苗期及2 a幼林期对比试验,对不同家系连续4 a胸径(1年生时为地径)、树高和材积性状进行分析比较,开展红椿优良家系早期选择。【结果】不同家系间胸径(地径)和树高性状在所有龄期都存在极显著差异。平茬后自苗期第2年起,后续3 a的所有胸径和树高性状相互间都呈显著或极显著相关。苗期第2年起后续3 a(2020—2022年),红椿家系的胸径、树高及材积性状遗传力皆超过0.85。根据不同家系不同性状的遗传增益大小,以材积增益为主,从17个家系中筛选出3个早期表现优良的家系,即鄂13家系、鄂15家系及鄂06家系,选择强度为17.65%。【结论】3个早期优良家系材积遗传增益均超过群体平均20%,选择强度大,早期生长优势明显,年均胸径生长量2.09 cm,年均树高生长量1.78 m,这些家系将成为湖北江汉平原地区红椿良种选育的重要种质资源。

江汉平原引种45年生黑杨派品种生长过程比较

以江汉平原引种的3个45年生黑杨派品种‘I-63’、‘I-69’和‘I-72’为研究对象,通过截取不同高度的圆盘进行树干解析,比较不同品种胸径、树高及材积生长过程,旨在为江汉平原黑杨大径材培育提供数据和技术支撑。结果表明,这3个品种的去皮胸径分别达到58.35、61.70、53.60 cm,树高分别为24.84、22.14、27.79 m,去皮材积分别为3.92、3.93、3.11 m^(3)。3个品种的胸径连年生长量最大值分别出现在第5年、第6年、第5年,树龄超过17年后胸径生长明显放缓;树高连年生长量最大值分别出现在第8年、第4年、第6年,树龄超过20年后树高生长接近峰值;材积年平均生长量最大值分别出现在第18年、第15年、第16年。对应3个品种的材积成熟龄,统计发现,‘I-63’、‘I-69’、‘I-72’材积速生期分别在第8~18、6~15、7~16年。整体来看,3个品种都具有较长的寿命和生长期,在江汉平原表现出极好的适应性,相对来说‘,I-69’干型较好,生长表现更为优良,推广价值更高。