GROUND WATER FLOW AND RUNOFF IN A COASTAL PLAIN STREAM1

ABSTRACT: The quantity, seasonality, and sources of flow were analyzed for two segments of Four Mile Branch, a small stream on the Coastal Plain of South Carolina using data obtained from USGS gauging stations. Flows in the “upstream segment,” a 12.6-km² watershed comprising the head waters of Four Mile Branch, averaged 0.129 m³ s^?1 and showed a distinctly seasonal pattern, with maximum flows in February and March and minimum flows in September and October. Inflow to the “downstream segment,” a 2.2-km² watershed associated with the main channel, averaged 0.059 m³ s^?1 and showed no seasonal patterns. Discharges per unit area of watershed were greater for the downstream segment, 0.83 m³ per year per m² of land surface, than for the upstream segment, 0.32 m³ per year per m². The differences in discharge rates and seasonalities between the two segments reflect differences in aquifers supplying the different segments. Analyses of Streamflow by hydrograph separation and Streamflow partitioning methods indicated that greater than 90 percent of the flows in the upstream and downstream segments were due to ground water-driven base flows.     

黄泛平原的土壤侵蚀灾害及防治对策

本文阐述了黄泛平原土壤侵蚀的特点，对侵蚀的形式、程度及严重危害，作了比较详细的分析，并从宏观上提出了一些防治对策。     

江汉平原耕地资源利用特征的城镇化模式

城镇化与耕地数量变化之间的关系是当前土地问题研究的焦点之一。利用1990-2004年江汉平原14个县市的统计数据资料，分析了在不同城市、不同城镇化阶段以及不同城镇化速度等条件下耕地面积所呈现的变化特点，并归纳出基于耕地资源利用特征的3种城镇化模式。     

三江平原生态环境状况研究

以三江平原各县（市）为研究基本单元,运用生态综合指数法对其生态环境状况进行评价,分析各县（市）生态环境状况。结果表明：三江平原各县（市）生态环境状况分为＂优＂、＂良＂和＂一般＂三个级别。＂优＂类的县（市）共3个,占全区面积的15.96%;＂良＂类的县（市）共19个,占全区面积的82.36%;＂一般＂类的县（市）1个,占全区面积的1.68%。     

基于水环境保护的苏州平原河网水利调度决策研究

平原河网地区作为经济发达地带,其水环境面临着巨大的压力.基于水环境保护,以水质改善率最大作为决策目标,通过构建平原河网水利调度决策理论模型来优选出最佳调度方案.并将该理论模型应用于苏州市平原河网地区,在模拟产生的6个不同水利调度方案中决策得到综合水质改善率最大的方案.决策结果显示:方案6的综合水质改善率最大,最有利于苏州平原河网地区的水环境保护,为最优调度方案.研究成果可为以水环境保护为目标的平原河网地区水利调度决策提供一定参考.     

A study of farmers' flood perceptions based on the entropy method: an application from Jianghan Plain,China

Using survey data from 280 farmers in Jianghan Plain, China, this paper establishes an evaluation index system for three dimensions of farmers' flood perceptions and then uses the entropy method to estimate their overall flood perception. Farmers' flood perceptions exhibit the following characteristics: (i) their flood‐occurrence, flood‐prevention, and overall flood perceptions gradually increase with age, whereas their flood‐effects perception gradually decreases; (ii) their flood‐occurrence and flood‐effects perceptions gradually increase with a higher level of education, whereas their flood‐prevention perception gradually decreases and their overall flood perception shows nonlinear change; (iii) flood‐occurrence, flood‐effects, and overall flood perceptions are higher among farmers who serve in public offices than among those who do not do so; (iv) the flood‐occurrence, flood‐effects, and overall flood perceptions of farmers who work off‐farm are higher than those of farmers who work solely on‐farm, contrary to the flood‐prevention perception; and (v) the flood‐effects and flood‐prevention perceptions of male farmers are lower than those of female farmers, but the flood‐occurrence and overall flood perceptions of male farmers are higher than those of female farmers.     

三江平原不同土地利用方式下土壤锰含量研究

通过对比分析三江平原典型的小叶章湿地、玉米地、水稻田、人工杨树林和岛状林土壤中锰（Mn）含量,研究了不同土地利用方式下土壤Mn分布特征及影响因素.结果表明,三江平原土壤Mn含量范围为107.73～2 798.99 mg.kg-1,平均为403.24 mg.kg-1,处于较低的水平.不同利用方式下土壤中Mn含量差异显著（F=9.272,P〈0.001）,表现出岛状林〉人工杨树林〉玉米地〉小叶章湿地〉水稻田的规律;总体上由表层至底层,各层土壤Mn含量表现为玉米地〉小叶章湿地〉水稻田,岛状林〉人工杨树林的规律,表明湿地开发为旱田后,土壤Mn将聚集,而开发为水田后,土壤Mn则流失.相关性分析表明,土壤中Mn含量与pH呈显著的负相关系（r=-0.279,P〈0.05）,Mn与S含量（r=0.383,P〈0.01）和可溶性有机碳含量（r=0.244,P〈0.05）呈显著的正相关关系,而与土壤有机质（SOM）和有效硫（Sa）含量相关性并不显著.环境因子的改变,可能是通过改变Mn的赋存状态而影响到土壤Mn含量.     

高氟地下水形成的组态分析——以豫东平原区为例

高氟地下水的形成机理研究是目前相关理论研究的关键问题,文章在系统思想指导下将传统的水化学类型分类方法进行改进,以组态分析的方法进行形成机理研究,得出以下结论:(1)高氟地下水的形成是多因子协同作用的结果;(2)作为非线性系统,高氟地下水的形成是个多态问题,就某一个区段而言是一个"暂态",一直处于多态的变化过程中,在此过程中各个因子相互作用形成多组态;(3)Na+>Ca2+型的水化学组态的高氟率(平均51%)明显大于Na+相似文献   

三江平原小叶章湿地系统硫的输入及输出动态

以三江平原小叶章(Calamagrostis angutifolia)湿地系统为研究对象,应用野外原位观测法研究了小叶章湿地系统硫的大气沉降输入及其输出规律.结果表明大气湿沉降中硫的月均含量变化明显,其原因主要与人类活动、降水强度及频次有关;硫沉降量具有明显的月变化特征,经估算三江平原小叶章湿地硫的年沉降总量(以S计)为113 mg·m-2·a·-1.小叶章湿地H2S、COS的排放通量均具有明显的季节和日变化规律.H2S和COS的平均释放通量(以S计)分别为O.34 μg·m-2·h-1和-0.29μg·m-2·h-1;小叶章湿地系统在生长季向大气排放H2S的量(以S计)为1.42 mg·m-2,从大气吸收COS的量(以S计)为1.83 mg·m-2.小叶章湿地系统硫的输入量远高于硫输出量,其差值为113.41 mg.m-2·a-1,这表明硫在小叶章湿地系统中处于累积状态,湿地存在潜在的酸化趋势.     

不同水耕年限稻田土壤水分运动特征研究

利用田间染色示踪和室内样品分析相结合的方法,研究了江汉平原不同水耕年限稻田土壤水分运动特征及其影响因素,期望为制定合理的稻田水分管理措施提供科学依据。结果表明:新稻田(水耕17a)与老稻田(水耕大于100a)土壤理化性质差异显著,引发土壤剖面内不同水分运动特征。新稻田垂直渗漏较老稻田明显,表现为新稻田有更大的染色深度。老稻田染色区域主要集中在耕作层,染色面积为48.52%;犁底层和底土层染色面积较小,仅为3.17%和0.2%。除耕作层外,新稻田其他土层染色面积均大于老稻田,且优先流特征较老稻田明显。老稻田侧向水分运动较新稻田强烈,其侧流剖面的染色面积(15.35%)显著高于新稻田(8.45%),老稻田侧向水流主要发生在犁底层以上。为减少稻田水分渗漏损失,老稻田可以通过减少农田-田埂-沟渠过渡区侧渗实现,而新稻田可采取少量多次的灌溉原则。