Characterising deep vadose zone water movement and solute transport under typical irrigated cropland in the North China Plain          下载免费PDF全文

Leilei Min  Yanjun Shen  Hongwei Pei  Bingdan Jing 《水文研究》2017,31(7):1498-1509

Understanding the dynamics and mechanisms of soil water movement and solute transport is essential for accurately estimating recharge rates and evaluating the impacts of agricultural activities on groundwater resources. In a thick vadose zone (0–15 m) under irrigated cropland in the piedmont region of the North China Plain, soil water content, matric potential, and solute concentrations were measured. Based on these data, the dynamics of soil water and solutes were analysed to investigate the mechanisms of soil water and solute transport. The study showed that the 0–15‐m vadose zone can be divided into three layers: an infiltration and evaporation layer (0–2 m), an unsteady infiltration layer (2–6 m), and a quasi‐steady infiltration layer (6–15 m). The chloride, nitrate, and sulphate concentrations all showed greater variations in the upper soil layer (0–1 m) compared to values in the deep vadose zone (below 2 m). The average concentrations of these three anions in the deep vadose zone varied insignificantly with depth and approached values of 125, 242, and 116 mg/L. The accumulated chloride, sulphate, and nitrate were 2,179 ± 113, 1,760 ± 383, and 4,074 ± 421 kg/ha, respectively. The soil water potential and solute concentrations indicated that uniform flow and preferential flow both occurred in the deep vadose zone, and uniform flow was the dominant mechanism of soil water movement in this study. The piston‐like flow velocity of solute transport was 1.14 m per year, and the average value of calculated leached nitrate nitrogen was 107 kg/ha?year below the root zone. The results can be used to better understand recharge processes and improve groundwater resources management.  相似文献   

Slump debris flows in the Akovolwo Mountains area of Benue State,Nigeria     

C. S. Nwajide  C. O. Okagbue  A. C. Umeji 《Natural Hazards》1988,1(2):145-154

In September 1979, rain-induced complex landslides occurred in two separate localities along the slopes of the Akovolwo Mountains near Jato-Aka in the Kwande Local Government area of Benue State, Nigeria.The two movements developed on bedrock slopes covered by a veneer of colluvium and (or) residuum no more than 1.5 to 2m deep. Each started as a slump and graduated into a debris flow. The slump, extending downhill a short distance away from the head scarp, had been reconstituted into a debris flow as the initial movement (sliding movement) of the soil mass caused remoulding of the saturated moving mass into viscous debris-laden mud. The resulting mass moved partly along a pre-existing mountain stream channel and partly along a fresh channel it cleared in the savanna forest. At the break of slope, the mass of boulders was dumped and a trail of smaller fragments littered the channels towards the Katsina-Ala River.  相似文献   

抚河中游地区几个地貌第四纪地质问题   总被引：1，自引：0，他引：1  

张金城 《华东地质学院学报》1989,12(3):43-46

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热流测量中垂向地下水运动干扰的校正方法   总被引：2，自引：0，他引：2       下载免费PDF全文

胡圣标  熊亮萍 《地质科学》1994,29(1):85-92

本文提出了一种地表热流测量中垂向地下水干扰的校正方法。并以江西萍乡和福建安溪的二个钻孔为例,说明了热流校正的具体过程。由于地下水对流传热的影响,垂向地下水渗透层内温度和热流随深度均呈指数分布。通过对钻孔测温数据的一维垂向Peclet数分析,可以确定渗透层内传导和对流热流分量以及热流的构成,从而得到未受地下水对流干扰的区域背景热流。这一方法不仅适用于渗透率结构均一的介质,也可用于水平层状介质。  相似文献   

滇中郝家河砂岩铜矿的地球化学及其成因意义   总被引：1，自引：0，他引：1  

秦德先  马宏 《地质论评》1994,40(2):183-192

本文论术字滇中生代地层与矿区及春外围马头山组中铜的时空分布与迁移富集规律，揭示了矿床的沉积－后期叠加改造成因。成矿作用经历了同生沉积形成矿源层，后期叠加改造形成矿体的过程。后期改造中铜元素发生了大量迁移，矿质主要来自矿体之下伏紫色矿源层。  相似文献   

Dynamics of fluvial and slope processes in the changing geomorphic environment of singapore     

Kalyani Chatterjea 《地球表面变化过程与地形》1994,19(7):585-607

The nature and rates of fluvial and slope processes change over time and space as urbanized areas replace forested land in Singapore. Storm-based and time-based data, from undisturbed rainforests, heavily disturbed construction sites, urban grass-covered slopes and an experimental plot, are collected to observe the impact of rainwater on the soil moisture conditions, surface microtopography, runoff generation, sediment movement, and ground lowering in the three different categories of land use. The undisturbed forested environment is characterized by high throughfall (58% of total rainfall) and frequent negative soil moisture suctions. The slow and unconcentrated overland flow during heavy storms is restricted by the forest floor microtopography. No rills develop. Ground lowering is recorded as 3·2–3·4 mm a^?1. But sediment movement is episodic and suspended sediment concentrations in overland flow are 172–222 mg l^?1. During urban construction, gully development is rapid on the bare slopes, runoff generation, voluminous, and sediment-laden discharges (5200–75498 mg l^?1) lead to sediment plumes at channel mouths. Ground lowering rates are measured at 132·4 mm a^?1. Once grass-covered, runoff carries less suspended sediment (800 mg l^?1) and ground lowering rates are reduced, but depend on the condition of the cover, ranging from 0·2 to 8·2 mm a^?1. As urban development continues, environments are altered both in time as well as spatially.  相似文献   

水网区区域水位模型及其应用   总被引：1，自引：0，他引：1       下载免费PDF全文

宋克强  王兴祥 《水科学进展》1995,6(3):205-210

水网区在宏观尺度上可被视为一种连续介质,可用水在多孔介质中的运动来比拟水网中水的运动.在这种概化条件下,推求出水网区水体运动的表述方法.利用这一方法建立的太湖水网区区域水位模型,与实际情况相比,获得了较好的效果.  相似文献   

太白山古冰川地貌与地质构造     

夏正楷 《冰川冻土》1990,(4)

太白山分布有更新世冰川地形,其冰川槽谷在平面上呈“十”字型排列;横剖面EW向的呈宽谷形,NS向是呈U型:纵剖面EW向比较平坦,SN向呈阶梯状,其中有许多断裂陡坎。冰斗均位于断裂交汇点,面积不大而深度却相当大。这些地形的形态特征可以用构造加以解释,断裂破碎带是最有利于冰川刨蚀的地段。  相似文献   

宁波地区镇海断裂带燕山晚期构造应力场研究   总被引：2，自引：0，他引：2  

吴树仁  孙叶 《地球科学》1990,15(6):607-615

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长江中下游地震同青藏高原北部地震的相关性     

李蓉川 《地震研究》1990,13(3):246-255

本文对比了1910—1987年发生的长江中下游地震和青藏高原北部地震,发现两者有比较好的对应关系。一般是,青藏高原北部先发生M≥6级地震,而后长江中下游地区发生M≥19/4级地震。对1910年以来的21次地震进行了统计分析,得到复相关系数R=0.74,能够在很高的显著性水平上通过F检验。地震活动在时间、空间、强度上的相关,现代构造运动及应力场等事实表明,长江中下游地震活动可能主要受青藏高原向东的横向推移运动的影响。  相似文献