An overview of the rangelands atmosphere-hydrosphere-biosphere interaction study experiment in northeastern Asia (RAISE)   总被引：1，自引：0，他引：1  

Michiaki Sugita  Jun Asanuma  Maki Tsujimura  Minjiao Lu  Dolgorsuren Azzaya 《Journal of Hydrology》2007,333(1):3-20

  相似文献   

基于CCSM4.0长期积分试验评估不同辐射强迫对中国干旱半干旱区降水的影响     

赵天保  从靖 《大气科学》2018,42(2):311-322

本文基于气候系统模式CESM4.0长期积分试验,分析评估了工业革命前（1850年）及当前（2000年）两种辐射强迫作用（分别为太阳活动和温室气体）对中国北方干旱半干旱区降水的影响。结果表明,模拟结果与观测之间尽管存在一定的偏差,但仍能再现降水气候态的空间分布以及季节变化特征;两种辐射强迫下的降水长期变化均无明显趋势,但二者的差异却呈现出70~100年的准周期振荡;由人类活动引起的当前辐射强迫作用对降水的多年际变率幅度有一定影响,造成极端强降水事件出现的概率增多,而由太阳活动引起的辐射强迫作用主要对降水多年代际周期具有一定的调制作用。进一步分析表明,两种辐射强迫下中国北方干旱半干旱区降水年多年代际变率的主要模态基本一致,但人类活动引起的辐射强迫作用会影响降水多年代际变率与热带海温异常的相互作用的强度,从而改变降水多年代际变率的幅度。  相似文献   

干旱条件下吐鲁番盆地相对湿润指数变化特征分析     

曹兴 《沙漠与绿洲气象(新疆气象)》2013,7(6):42-49

利用干旱条件下的吐鲁番盆地1981-2010年的逐月降水、气温资料,通过Thornthwaite方法计算潜在蒸散量确定气候相对湿润指数,并分析其时空变化特征;同时应用小波分析及Mann-Kendall法,对相对湿润指数进行突变和周期分析,结果表明：近30 a来,降水量呈非显著性的减少趋势,气温增暖趋势明显,倾向率为0.53益·（10 a）-1;在气候变暖的背景下,潜在蒸散量呈波动增加趋势,空间分布差异显著（P〈0.05）;相对湿润指数呈较弱的减小态势,气候总体趋于干旱化,表现为：鄯善最强,吐鲁番次之,托克逊相对较弱;相对湿润指数未出现显著的转折年份和突变时间区域;周期变化表现为较强的对称性,4～5a的变化周期一致性较好。研究区域内气温升高,降水减少,是导致气候干旱化趋势得以维持和加剧的重要因素。  相似文献   

采空区储水干旱区保水采煤新途径     

李文平  李涛  陈伟  常金源  王启庆 《工程地质学报》2014,22(5):1003-1007

我国西北干旱半干旱地区水资源总体贫乏,但煤炭储量丰富,且埋藏浅。煤炭开采覆岩土破裂常发育到地表,破坏浅表层水资源,造成潜水水位下降、地表水枯竭,生态地质环境恶化,实施水资源保护性开采(保水采煤)是西北干旱地区煤炭科学开采的唯一选择。本文叙述了保水采煤的历史和现状,分析了采空区储水的基本条件和机理,给出了采空区储水的水量预计方法,并以实例说明了采空区储水水量和水质效果,认为采空区储水是西北干旱区浅埋煤层大规模保水开采的最有效途径。  相似文献   

The ecological features and significance of hydrology within arid inland river basins of China     

W. Genxu  C. Guodong 《Environmental Geology》1999,37(3):218-222

 Hydrology and ecology are two important factors affecting the rational utilization of limited water resources within the arid inland basins of China. They depend on, are influenced by, and interact with each other. But, the functions and significance of the hydrological ecology vary from upper through intermediate to lower reaches. Abundant rainfall and large runoff in the upper regions favor the vegetation growth, and the bushy vegetation helps conserve water resources. The large-scale reclamation in the intermediate regions leads to many sustainable oases, but with severely changed hydrological conditions and destroyed ecological systems. Human activities result in the degradation of the vegetation and declination of the ecological system at the intermediate and lower regions. It is necessary to establish study approaches to ecological hydrology in arid inland river basins. Received: 30 October 1997 · Accepted: 26 May 1998  相似文献   

Predicting gully densities at sub-continental scales: a case study for the Horn of Africa     

Matthias Vanmaercke  Yixian Chen  Nigussie Haregeweyn  Sofie De Geeter  Benjamin Campforts  Wouter Heyndrickx  Atsushi Tsunekawa  Jean Poesen 《地球表面变化过程与地形》2020,45(15):3763-3779

Despite its environmental and scientific significance, predicting gully erosion remains problematic. This is especially so in strongly contrasting and degraded regions such as the Horn of Africa. Machine learning algorithms such as random forests (RF) offer great potential to deal with the complex, often non-linear, nature of factors controlling gully erosion. Nonetheless, their applicability at regional to continental scales remains largely untested. Moreover, such algorithms require large amounts of observations for model training and testing. Collecting such data remains an important bottleneck. Here we help to address these gaps by developing and testing a methodology to simulate gully densities across Ethiopia, Eritrea and Djibouti (total area: 1.2 million km²). We propose a methodology to quickly assess the gully head density (GHD) for representative 1 km² study sites by visually scoring the presence of gullies in Google Earth and then converting these scores to realistic estimates of GHD. Based on this approach, we compiled GHD observations for 1,700 sites. We used these data to train sets of RF regression models that simulate GHD at a 1 km² resolution, based on topographic/geomorphic, land cover, soil and rainfall conditions. Our approach also accounts for uncertainties in GHD observations. Independent validations showed generally acceptable simulations of regional GHD patterns. We further show that: (i) model performance strongly depends on the amount of training data used, (ii) large prediction errors mainly occur in areas where also the predicted uncertainty is large and (iii) collecting additional training data for these areas results in more drastic model performance improvements. Analyses of the feature importance of predictor variables further showed that patterns of GHD across the Horn of Africa strongly depend on NDVI and annual rainfall, but also on normalized steepness index (k_sn) and distance to rivers. Overall, our work opens promising perspectives to assess gully densities at continental scales. © 2020 John Wiley & Sons, Ltd.  相似文献