Temporal dynamics of soil water balance components in a karst range in southeastern Spain: estimation of potential recharge

Abstract

This paper analyses the temporal dynamics of soil water balance components in a representative recharge area of the Sierra de Gádor (Almeria, southeastern Spain) in two hydrological years. Two approaches are used to estimate daily potential recharge (PR): Approach 1 based on deriving PR from the water balance as the difference between measurements of rainfall (P) and actual evapotranspiration (E) obtained by eddy covariance; and Approach 2 with PR obtained from the dynamic pattern of the soil moisture (θ) recorded at two depths in the site's thin soil (average 0.35 m thickess). For the hydrological year 2003/04, which was slightly drier than the 30-year average, E accounted for 64% of rainfall and occurred mainly in late spring and early summer. The PR estimated by Approach 1 was 181 ± 18 mm year^-1 (36% of rainfall), suggesting an effective groundwater recharge in the study area. In the unusually dry hydrological year 2004/05, E was about 215 mm year^-1, close to the annual rainfall input, and allowing very little (8 ± 12 mm year^-1) PR according to Approach 1. Estimation of PR based on Approach 2 resulted in PR rates lower than those found by Approach 1, because Approach 2 does not take into account the recharge that occurs through preferential flow pathways (cracks, joints and fissures) which were not monitored with the θ probes. Moreover, using Approach 2, the PR estimates differed widely depending on the time scale considered: with daily mean θ data, PR estimation was lower, especially in late spring, while θ data at 30 min resolution yielded a more reliable prediction of the fraction of total PR resulting from the downward movement of soil water by gravity.

Citation Cantón, Y., Villagarcía, L., Moro, M. J., Serrano-Ortíz, P., Were, A., Alcalá, F. J., Kowalski, A. S., Solé-Benet, A., Lázaro, R. & Domingo, F. (2010) Temporal dynamics of soil water balance components in a karst range in southeastern Spain: estimation of potential recharge. Hydrol. Sci. J. 55(5), 737–753.     

川滇及邻区Pn波速度结构和各向异性研究

川滇地区是中国大陆构造变形及地震活动最强烈的区域之一.本文利用从国际地震中心(ISC)、中国地震台网以及云南、四川、重庆三个省级地震台网的地震观测报告中严格挑选出的53673个Pn波到时数据,用Pn波层析成像方法反演了川滇地区的Pn波速度结构和各向异性.结果表明该地区上地幔顶部速度结构的横向变化与现代构造运动有明显的关联:盆地地区上地幔顶部速度明显高于其周边区域,四川盆地尤为突出,其上地幔顶部P波速度是整个研究区域的高值;上地幔顶部P波速度低值区与研究区现代火山活动区域(如腾冲)及高热泉活动区域(如康定)有明显的相关性.强震大都发生在Pn波速低值区或Pn波速低值边界区.Pn波速度低速带与狭义的南北地震带相吻合,反映出上地幔顶部的流变性对构造应力的传递起着重要作用.Pn波各向异性表明:位于川青块体与四川盆地交界的龙门山地区,快波方向与该区域绝对运动方向不一致,而是基本沿龙门山断裂走向,这表明该地区的各向异性主要受龙门山断裂对Moho面切割变形的影响.而在其他区域的Pn波各向异性方向大体与当地块体的绝对运动方向一致,说明其各向异性主要是由板块运动产生的软流圈变形引起.     

近距离交叉隧洞爆破对既有隧道的振动影响

结合南山下隧洞下穿温福客运专线钱仓山隧道工程,实时监测近距离交叉隧洞爆破施工对既有隧道的振动影响。实测结果表明,（1）迎爆面位置影响既有隧道断面的爆破振动速度分布;震源距离测点大于30 m时,距离是爆破振动的主要影响因素;震源距离测点小于30 m时,主要影响因素则为装药量与距离。（2）岩体越坚硬完整,爆破振动波传播衰减越慢。采用导洞先行预留光面爆破、导洞爆破掏槽眼和周边眼及底板眼分开起爆、控制最大段装药量等措施,可有效地降低爆破振动影响,控制其对钱仓山隧道的影响,对类似工程有借鉴作用。     

水饱和裂纹对地壳岩样中地震波速及各向异性的影响

选择４种地壳岩石样品,经干燥或水饱和处理后在不同围压条件下测量了在其中传播的纵、横波的速度及其各向异性．在大气压条件下低孔隙度(＜１％岩样中,水饱和样品中的纵波速度明显地比干燥样品中的高,但横波速度的差别不大．因为在低孔隙度岩样中纵波速度对孔隙流体的反应比横波速度敏感,可以用泊松比的变化来反映随着围压的增加晶粒间流体对弹性波传播特性的影响．根据实验数据,按Ｏ’Ｃｏｎｎｅｌｌ模型分别计算了干燥和水饱和岩样中的裂纹密度,与通过实测体应变曲线得到的裂纹孔隙度十分吻合．利用横波的速度和偏振特性可以推断岩样中定向排列微裂纹的空间取向情况．研究表明,同时测量在岩样中传播的纵、横波的速度,通过Ｖｐ／Ｖｓ比值可以给出有关颗粒边界流体的证据,也可以估计岩样中的裂纹密度．     

中国陆块海相盆地成钾条件与预测研究进展综述

中国古代海相钾盐找矿是一个“久攻不破”的难题,古代海相及海陆交互相盆地能否成钾也是长期争议的问题,也就是中国小陆块能否成钾、成大钾矿的关键问题。为此,本文以板块构造运动为主线,对中国主要小陆块漂移历史、成盆构造、古气候、古地理及海相/海陆交互相蒸发岩沉积特征进行了系统梳理和总结;在此基础上,基于盆地“构造-物源-气候”三要素耦合成钾理论,分析中国小陆块海相盆地成钾条件、成矿机理;同时,总结和借鉴全球海相钾盐成矿标志,建立钾盐成矿评价指标体系。基于这些研究基础,借助对主要陆块的区域构造和古地理特征、物质来源、古气候面貌等恢复及分析,对主要陆块的海相成钾潜力进行评价,同时预测找钾战略靶区。钾盐成矿模式研究表明:兰坪—思茅盆地白垩系、上扬子陆块四川盆地中—下三叠统、华北陆块陕北盆地中奥陶统及塔里木陆块库车盆地古近系等盆地及其层位具有较大的成钾潜力。结合成钾指标对比分析,优选圈定了思茅盆地南部、四川盆地中东部及塔里木的库车盆地等战略靶区内较为明确的重点靶区,可以进一步开展钻探验证。这些研究成果为在中国继续开展海相钾盐成矿研究和找钾提供科学依据。     

1979—2015 年罗斯海海冰运动速度变化

基于美国冰雪数据中心的月平均海冰运动和海冰密集度数据, 建立了1979—2015 年罗斯海海冰运动 速度时间变化序列, 揭示了海冰运动速度的年际和季节变化特征, 探讨了海冰运动速度和海冰范围之间可 能存在的联系, 最后对影响海冰运动速度变化的因素进行了分析。结果表明, 1979—2015 年罗斯海海冰运动 速度总体呈现加快趋势, 海冰运动速度增加趋势最快的季节为秋季, 其次是冬季、春季和夏季。冬季海冰平 均运动速度最大, 依次是秋季、春季和夏季。海冰运动速度与海冰范围在37 年间均呈现上升趋势, 海冰范 围变化滞后海冰运动速度1—2 个月, 两者呈显著正相关关系, 海冰运动速度的增加导致罗斯海海冰范围不 断扩张, 进而影响南极整体海冰分布。罗斯海海冰运动速度与风速之间存在显著正相关关系, 风场是影响海 冰运动速度的一个直接因素。除此之外, 海冰运动还受到包括气压场、洋流场以及海洋阻力系数等的影响。     

呼和浩特市一次大暴雨天气的湿位涡诊断分析

对1998年7月12日发生在呼和浩特地区的大暴雨天气过程进行了湿位涡初步诊断分析。结果表明:湿位涡在暴雨预报中具有较好的指示性,当对流层低层MPVl<0,同时MPV2>0时,暴雨易发生。从500hPa到对流层中高层,在切变线的附近有一个大的湿位涡正值中心,各层中心的位置基本相对应,从中层到高层略向北倾,越到高层中心值越大。强降水位于低层湿位涡高值区东北侧正位涡较小的地区,并与位涡斜压部分的负值中心相对应,随着斜压负值中心强度的增强,暴雨加强。     

柴西乌南-绿草滩地区古近系下干柴沟组下段储盖组合与勘探潜力

运用层序地层学的理论和方法,综合钻井、测井和三维地震资料,在柴西乌南-绿草滩地区古近系下干柴沟组下段识别出两个层序界面,将其划分为1个长期基准面旋回(三级层序) LSC1和4个中期基准面旋回(四级层序) MSC1、MSC2、MSC3和MSC4。在等时地层格架约束下,详细分析了研究区储集层、盖层及储盖组合的发育规律与基准面旋回的内在联系,指出本区古近系下干柴沟组下段具有较大的油气勘探潜力。     

新疆库木库里盆地铜矿地质特征及找矿前景

新疆库木库里盆地砂砾岩型铜矿带位于东昆仑成矿带西段东昆中断裂北侧新生代陆相盆地中 ,与西部且末县嘎其哥洛德和克孜勒小型砂砾岩型铜矿组成近2 0 0km长的大型砂砾岩型铜矿化带。铜矿化赋存于石马沟组上段 (E3 S1)砂岩中。围岩中铜含量一般低于地壳丰度值 ,南部火箭山地区发现有斑岩型铜矿化、昆中结合带也发现规模巨大的铜矿化带 ,它们可能是本区铜矿化的矿源层。铜矿化呈透镜状、似层状 ,剖面上已发现三层铜矿化 ,其中上部铜矿化较好。地表氧化矿石矿物组合简单 ;矿石构造为条带状、浸染状、团块状 ,填隙结构。铜矿化受湖泊三角洲相、三角洲前缘亚相的近岸砂坝、远岸砂坝的砂体控制。     

Sediment routing hypothesis for pool‐riffle maintenance

This paper provides comprehensive evidence that sediment routing around pools is a key mechanism for pool‐riffle maintenance in sinuous upland gravel‐bed streams. The findings suggest that pools do not require a reversal in energy for them to scour out any accumulated sediments, if little or no sediments are fed into them. A combination of clast tracing using passive integrated transponder (PIT) tagging and bedload traps (positioned along the thalweg on the upstream riffle, pool entrance, pool exit and downstream riffle) are used to provide information on clast pathways and sediment sorting through a single pool‐riffle unit. Computational fluid dynamics (CFD) is also used to explore hydraulic variability and flow pathways. Clast tracing results provide a strong indication that clasts are not fed through pools, rather they are transported across point bar surfaces, or around bar edges (depending upon previous clast position, clast size, and event magnitude). Spatial variations in bedload transport were found throughout the pool‐riffle unit. The pool entrance bedload trap was often found to be empty, when the others had filled, further supporting the notion that little or no sediment was fed into the pool. The pool exit slope trap would occasionally fill with sediment, thought to be sourced from the eroding outer bank. CFD results demonstrate higher pool shear stresses (τ ≈ 140 N m^–2) in a localized zone adjacent to an eroding outer bank, compared to the upstream and downstream riffles (τ ≈ 60 N m^–2) at flows of 6 · 2 m³ s^–1 (≈ 60% of the bankfull discharge) and above. There was marginal evidence for near‐bed velocity reversal. Near‐bed streamlines, produced from velocity vectors indicate that flow paths are diverted over the bar top rather than being fed through the thalweg. Some streamlines appear to brush the outer edge of the pool for the 4 · 9 m³ s^–1 to 7 · 8 m³ s^–1 (between 50 and 80% of the bankfull discharge) simulations, however complete avoidance was found for discharges greater than this. Copyright © 2013 John Wiley & Sons, Ltd.