Modelling the effect of changing precipitation inputs on deep soil water utilization          下载免费PDF全文

Ji Qi  Daniel Markewitz  David Radcliffe 《水文研究》2018,32(5):672-686

Forests in the Southeastern United States are predicted to experience future changes in seasonal patterns of precipitation inputs as well as more variable precipitation events. These climate change‐induced alterations could increase drought and lower soil water availability. Drought could alter rooting patterns and increase the importance of deep roots that access subsurface water resources. To address plant response to drought in both deep rooting and soil water utilization as well as soil drainage, we utilize a throughfall reduction experiment in a loblolly pine plantation of the Southeastern United States to calibrate and validate a hydrological model. The model was accurately calibrated against field measured soil moisture data under ambient rainfall and validated using 30% throughfall reduction data. Using this model, we then tested these scenarios: (a) evenly reduced precipitation; (b) less precipitation in summer, more in winter; (c) same total amount of precipitation with less frequent but heavier storms; and (d) shallower rooting depth under the above 3 scenarios. When less precipitation was received, drainage decreased proportionally much faster than evapotranspiration implying plants will acquire water first to the detriment of drainage. When precipitation was reduced by more than 30%, plants relied on stored soil water to satisfy evapotranspiration suggesting 30% may be a threshold that if sustained over the long term would deplete plant available soil water. Under the third scenario, evapotranspiration and drainage decreased, whereas surface run‐off increased. Changes in root biomass measured before and 4 years after the throughfall reduction experiment were not detected among treatments. Model simulations, however, indicated gains in evapotranspiration with deeper roots under evenly reduced precipitation and seasonal precipitation redistribution scenarios but not when precipitation frequency was adjusted. Deep soil and deep rooting can provide an important buffer capacity when precipitation alone cannot satisfy the evapotranspirational demand of forests. How this buffering capacity will persist in the face of changing precipitation inputs, however, will depend less on seasonal redistribution than on the magnitude of reductions and changes in rainfall frequency.  相似文献   

内蒙古鲁新井田水文地质条件研究          下载免费PDF全文

赵志强  安美艳  高奎锋  王兆亮  王福芝 《山东国土资源》2018,34(6)

矿产资源开发导致了地下水失衡,地下水失衡又给矿产开发造成了极大的安全隐患,近年来,矿产资源开发与地下水环境保护之间的矛盾愈发凸显。通过对内蒙古鲁新井田典型的水文地质条件进行分析研究,分析采矿导致地下水失衡机理,深入剖析矿井开采充水条件及矿山开发对地下水环境的影响,合理提出了促进矿产开发与地下水保护相互协调的对策建议,为实现"采矿保水"协调统一提供了基础地质依据。为类似地区矿产开发过程中遵循自然规律,趋利避害,保障生产安全,保护地下水环境安全,实现资源绿色开发有较好的指导借鉴作用。  相似文献   

利用超快速精密星历约束的北斗卫星实时精密定轨     

范磊  施闯  李敏 《大地测量与地球动力学》2018,38(9):937-942

以广播星历为起算轨道的北斗卫星实时滤波精密定轨往往需要较长收敛时间，针对此，提出利用超快速精密星历约束的实时精密定轨方法。通过MGEX跟踪网全球分布的51个测站连续7 d的实测数据，利用平方根信息滤波对北斗卫星实时精密轨道进行确定，并以3 d解事后轨道作为参考，评估北斗卫星实时滤波轨道精度。结果表明，利用广播星历作起算轨道时，北斗实时滤波轨道平均需要经过15 h收敛才能达到稳定，而新方法在这段时间内轨道变化较为平稳，未出现明显的收敛现象，并且7 d时间内GEO卫星在切向、法向和径向上RMS分别优于2.5 m、20 cm和30 cm，IGSO和MEO卫星在3个方向上分别优于30 cm、15 cm和10 cm。
  相似文献   

Revisiting Sustainable Development of Dry Valleys in Hengduan Mountains Region   总被引：5，自引：1，他引：4  

TANGYa XIEJiasui SUNHui 《山地科学学报》2004,1(1):38-45

Dry valleys are a striking geographic landscape in Hengduan Mountains Region and are characterized by low rainfall, desert type of vegetation and fragile environment. Past efforts and resources have been concentrated mainly on rehabilitation of degraded ecosystem and fragile environment, particularly reforestation, while socio-economic development has been largely overlooked. Despite successes in pocket areas, the overall trend of unsustainability and environmental deterioration are continuing. It is important to understand that uplift of the Tibetan Plateau is the root cause of development of dry valleys, and development and formation of dry valleys is a natural process. Human intervention has played a secondary role in development of dry valleys and degradation of dry valleys though human intervention in many cases has speeded up environmental degradation of the dry valleys. It is important to understand that dry valleys are climatic enclaves and an integrated approach that combines rehabilitation of degraded ecosystems and socio-economic development should be adopted if the overall goal of sustainable development of dry valleys is to be achieved. Promotion of niche-based cash crops, rural energy including hydropower, solar energy, biogas and fuelwood plantation is recommended as the priority activities.  相似文献   

广西河池地区矿产资源勘查成果展销会情况介绍     

项开文 《南方国土资源》1996,(3)

１９９５年７月１１日—１２日，广西地矿厅和河池地区行署首次联合举办矿产资源勘查成果展销会，会址设在河池市，与会代表１３０余人。展销会提交大会展销的矿产资源勘查成果３８项，引资勘查项目３８项。经买卖双方三天的洽谈，涉及到的项目２５项，会议期间签订矿产资源勘查成果合同协议４项，愈千万元，取得较好的社会经济效益。为地勘资金多渠道来源开辟了新路子，对促进地勘单位地质找矿工作及勘查成果有偿使用发挥了重要作用  相似文献   

桂西古侵蚀沉积间断面型金矿床(续载)     

陈开礼 《南方国土资源》2001,14(1):37-40

古侵蚀沉积间断面型金矿是桂西的主要金矿床类型。文章着重分析该类型金矿成矿地质条件 ,论述矿床成因及成矿机理 ,认为此类型金矿易采易冶 ,经济效益显著 ,建议加大开发力度。  相似文献   

贵港市矿业发展现状与对策     

李东昌 《南方国土资源》2002,15(1):57-60

文章从贵港市矿产资源情况出发 ,通过对开发现状及存在问题的分析 ,探讨保证资源的合理开发和永续利用 ,为经济建设提供物质支撑的理念 ,提出了矿业可持续发展的对策。  相似文献   

Modelling the effect of low soil temperatures on transpiration by Scots pine     

Per‐Erik Mellander  Manfred Sthli  David Gustafsson  Kevin Bishop 《水文研究》2006,20(9):1929-1944

For ecosystem modelling of the Boreal forest it is important to include processes associated with low soil temperature during spring‐early summer, as these affect the tree water uptake. The COUP model, a physically based SVAT model, was tested with 2 years of soil and snow physical measurements and sap flow measurements in a 70‐year‐old Scots pine stand in the boreal zone of northern Sweden. During the first year the extent and duration of soil frost was manipulated in the field. The model was successful in reproducing the timing of the soil warming after the snowmelt and frost thaw. A delayed soil warming, into the growing season, severely reduced the transpiration. We demonstrated the potential for considerable overestimation of transpiration by the model if the reduction of the trees' capacity to transpire due to low soil temperatures is not taken into account. We also demonstrated that the accumulated effect of aboveground conditions could be included when simulating the relationship between soil temperature and tree water uptake. This improved the estimated transpiration for the control plot and when soil warming was delayed into the growing season. The study illustrates the need of including antecedent conditions on root growth in the model in order to catch these effects on transpiration. The COUP model is a promising tool for predicting transpiration in high‐latitude stands. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

A 20‐ka climate record from Central Himalayan loess deposits     

R. K. Pant  N. Basavaiah  N. Juyal  N. K. Saini  M. G. Yadava  E. Appel  A. K. Singhvi 《第四纪科学杂志》2005,20(5):485-492

The southwest monsoon that dominated Central Himalaya has preserved loessic silt deposits preserved in patches that are proximal to periglacial areas. The occurrence of such silts suggests contemporary prevalence of cold and dry northwesterly winds. Field stratigraphy, geochemistry, mineral magnetism, infrared stimulated luminescence (IRSL) and radiocarbon dating has enabled reconstruction of an event chronology during the past 20 ka. Three events of loess accretion could be identified. The first two events of loess deposition occurred betweem 20 and 9 ka and were separated by a phase of moderate weathering. Pedogenesis at the end of this event gave rise to a well‐developed soil that was bracketed around 9 to > 4 ka. This was followed by the third phase of loess accretion that occurred around 4 to > 1 ka. Episodes of loess deposition and soil formation are interpreted in terms of changes in the strength of the Indian southwest monsoon. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

柿竹园矿床大理岩型锡矿石工艺矿物学研究   总被引：1，自引：0，他引：1  

谭延松 《湖南地质》1991,10(3):223-228

大理岩型锡矿石产于燕山早、中期千里山花岗岩与中、上泥盆统灰岩的外接触带。矿石呈细脉、网脉浸染状,锡矿物有:锡石、黄锡矿,富钛尼日利亚石、尼日利亚石和木锡矿,脉石矿物绿帘石、石榴石、电气石、萤石、方解石及磁黄铁矿等亦含锡,锡主要呈锡的浊立矿物存在,占总锡量的89.78％,其中锡石锡占总锡量的80.01％,其次有呈类质同象形式存在的锡,在绿帘石、石榴石、电气石等矿物中以Sn~(4+)取代Fe~(3+),这类锡占总量的8.33％。工艺矿物学研究表明,该类锡矿石以“贫”、“细”、“杂”为特征。锡不仅十分分散,而且品位偏低,矿石矿物组合及镶嵌关系复杂、相互包裹,紧密连生;锡矿物粒度微细,粒径一般为0.2～0.01mm,部分为<0.0l～0.002mm,是一种难选的锡矿石类型。通过锡的回收试验,采用选冶联合工艺流程,预测锡的最佳回收率可达50％以上。  相似文献