西北干旱半干旱区生态移民可持续发展策略探讨

近二十多年来，我国西北干旱半干旱区生态移民取得了巨大的成就．但还存在一些不可忽视的问题．章在分析西北干旱半干旱区生态移民存在基本问题的基础上．本着时序协调性、空间协调性、要素协调性等原则．探讨了实现西北干旱半干旱区生态移民可持续发展的四大战略，生态优先战略、多元经济战略、城镇化战略和科教振兴战略．以期对西北地区生态移民建设提供决策参考．     

浅谈西北地区地理环境对城镇布局的制约——以兰州市域城镇为例

兰州地处我国西北黄土高原干旱区中心,受干旱、半干旱地区地理环境、交通、资源等因素影响,市域城镇区域空间分布差异大。本论述分析了地理环境对城镇布局的制约,提出了将制约因素转化为有利条件的思路。     

东亚干旱、半干旱区范围与边界层高度变化的关系分析

采用1979-2014年ERA-Interim再分析资料,对东亚干旱、半干旱区边界层高度(BLH)的时空变化特征进行了系统分析,初步探讨了BLH变化在干旱、半干旱区范围变化中的反馈作用.结果表明,BLH整体呈经向扁平分布,以塔克拉玛干沙漠为高值中心,其西部和北部边界层高度变化梯度较大、向东变化则较平缓,干旱、半干旱区的分界线与边界层高度的分布存在较好的一致性.36 a数据分析可知,边界层高度呈增大的趋势,分析年代际尺度变化发现,从20世纪末到21世纪初,边界层高度在高值中心及其北部呈先增后减的趋势,其西部、中部和东部的边界层高度呈减、增、减的年代际变化趋势,干旱、半干旱区分界线也有对应的变化趋势.边界层高度增加,分界线向外扩张;边界层高度减小,分界线向内缩减,干旱、半干旱区的范围也相应地扩大和缩小,进一步表明东亚干旱、半干旱区范围的变化与边界层高度的变化有着较好的对应关系.边界层高度的变化对干旱、半干旱区范围变化存在着反馈作用.边界层高度升高,增加了水分蒸发,使得大气中的水汽含量增多,空气变得湿润,在一定程度上缓解了气候变干的趋势,阻止干旱、半干旱区范围的持续扩大.     

中国北方干旱区和半干旱区近60年气候变化特征及成因分析

利用1951-2011年中国756个观测站的月降水资料,分析了北方干旱区和半干旱区暖季降水的变化.结果表明干旱区和半干旱区的降水近60年来表现出相反的变化趋势:干旱区的暖季降水整体是增加的,增长速率为0.27 mm/a,而半干旱区的暖季降水整体是减少的,减少速率为0.80 mm/a.存在这样的差异主要是因为两个区域受不同的环流系统所控制,即干旱区为西风控制区,而半干旱区则为季风区.通过对两个区域降水偏多(偏少)年大气环流的合成分析发现,当西风气流加强、位置偏南,黑海、里海和巴尔喀什湖的水汽被输送到我国干旱区,有利于该地区的降水,反之干旱区降水则偏少;而当东亚夏季风较强时,水汽向西能到达甘肃中部(105?E),向北能到达整个华北和东北地区,因此半干旱区降水偏多,反之半干旱区降水则偏少.     

地理学在21世纪大西北开发中的作用

第四次全国干旱与半干旱区地理建设学术会议于１９９８年７月１３日至１６日在宁夏银川市举行．这是中国地理学会干旱与半干旱区地理建设分会的系列会议,每两年召开一次,这次银川会议最为成功．本次会议由宁夏大学地理系和宁夏回族自治区地理学会承办,来自全国各地的７...     

三江源地区干旱指数时空演变及成因分析

基于1966—2017年三江源区11个气象台站的逐日气象资料,运用彭曼公式(Penman Monteith)计算潜在蒸散量(ET0)并进一步分析干旱指数(aridity index,AI)对于气候因子的敏感性.结果表明:三江源地区1966—2017年干旱指数总体呈明显下降趋势(0.1/10 a),年均值为1.76,属于半干旱区;研究区5年的干旱指数距平值于1990年后为负值,表明该区域气候于1990年后趋于湿润化,Mann-Kendall突变检验结果表明干旱指数分别在1988年和1992年发生突变;根据干旱指数的空间分布特征,将三江源区划分为东南湿润区、中部半湿润区和北部干旱区,其余大部分地区属于半干旱区和半湿润区;干旱指数对日照时数和相对湿度响应较为敏感,敏感系数分别为9.3和6.4,但对平均温度极为不敏感.相对贡献分析结果表明,三江源地区的干旱指数主要受相对湿度和平均风速的控制.     

景观结构调整和干旱半干旱区水资源的可持续利用

分析了干旱半干旱区存在的一些生态问题,论述了与干旱半干旱区水资源可持续利用有关的景观生态学理论,其中包括景观连通性、自然干扰、河流廊道和斑块水文功能.在此基础上,提出了一些景观结构调整措施:1)调整水源涵养斑块和耗水斑块面积组成比例和空间分布;2)营建防风林带;3)保护和恢复河流廊道;4)保留景观内水体斑块;5)拆除某些水利设施等.这种景观尺度上的结构调整因其更大的宏观性和整体性优势,将起到农业作物结构调整所不能起到的一些作用,这对改善半干旱区水资源状况和实现半干旱区水资源可持续利用具有重要意义.     

调整产业结构是干旱,半干旱区环境治理的重要途径

干旱、半干旱区环境治理问题其实质是一个经济发展的问题,而调整产业结构既是经济发展所必需,更是环境整治所必要。调整大产业结构的重点在于改变这一区域单靠农业的一元结构,大力发展工矿业和第三产业,用经济收益推进环境治理;调整小产业结构的重点在于增大该区域林、牧比重和大力发展灌溉农业,用“绿地效应”和“灌溉效应”推进环境治理。     

中国干旱半干旱区地理信息资源开发利用初探

干旱半干旱区有着丰富的地理信息资源,信息社会的到来和市场经济的发展,为地理信息资源的开发利用提供了机遇和条件,科学技术的高速发展也使地理信息资源的开发利用具有了新的技术手段．结合本地区的特点,阐述了干旱半干旱区地理信息资源的特征,提出了合理开发地理信息资源的有效途径     

"软工程"战略与西北干旱半干旱区水资源的合理利用

在简述了西北干旱半干旱区水资源特点与问题的基础上,分析了水资源浪费的主要原因,提出了水资源合理利用的“软工程”战略及其具体措施,强调从改善水资源环境,建立节水型社会及治理水土流失等方面来利用与配置干旱半干旱区的水资源。     

137Cs应用于我国土壤侵蚀研究评述

^137Cs示踪法技术目前已被广泛应用于长期的土壤侵蚀估算中，但主要局限于水蚀研究领域，在风蚀方面进行的研究则较少。土壤风蚀是导致干旱半干旱地区土地退化和区域环境恶化的最重要原因之一。探讨、研究格进一步完善^137Cs技术在土壤侵蚀方面的研究，尤其是在我国西部风蚀地区土壤侵蚀中的应用，可以提供独立的土壤侵蚀和堆积的数据以及空间分布，对初步测算区域风蚀速率、风蚀时间序列和反映环境变化，为我国西部地区土地资源合理利用、环境整治以及生态建设提供定量的科学依据具有十分重要的意义。初步论述了^137Cs技术在我国土壤侵蚀研究中的进展，探讨了其在西部风蚀地区土壤风蚀研究现状、应用前景和需要注意的问题，并提出了一些建议。     

Decadal-scale precipitation variations in arid and semiarid zones of northern China during the last 500 years

Regional decadal precipitation reconstructions for the arid and semi-arid zones of northern China were established by the use of different palaeoclimate archives such as ice-cores, tree-rings, lake sediments and written historical documents. Local rainfall reconstructions from single sites were averaged to obtain regional precipitation records for western and eastern regions of an arid and semiarid zone of northern China, respectively. All established regional precipitation curves display 5 dry periods, each lasting about 50 years. Meanwhile, precipitation reconstructions show regional dissimilarities. During the last 500 years, the trends of precipitation change in the eastern arid region are basically consistent with those in the western and eastern regions of the semiarid zone. Precipitation variations in the western arid region are unique, showing significant local patterns of rainfall variability. Maximum entropy method (MEM) spectral estimates show that each regional precipitation series contains stationary century-scale periodicities of about 120 a.Singular spectrum analysis was applied to isolating the century-scale oscillation signals from the regional proxy precipitation series. Significant periods with wavelengths of 121.4a, 154.6a, 124.3a, 118.6a, 108.5a and 121.4a were found 26.56%, 26.44%, 28.87%, 18.67%, 33.48% and 34.04% of the variances of the original series for the western arid zone,the eastern arid zone, the whole arid zone, the western semiarid zone, the eastern semiarid zone and whole northern China, respectively.     

干旱半干旱地区农田风蚀危害及其对策研究

土壤风蚀是我国干旱半干旱地区土地退化的主要原因之一,严重制约着农业的可持续发展.笔者从土壤风蚀发生机理、影响因子的角度探讨了干旱半干旱地区农田风蚀危害及防治对策,提出了实施保护性耕作是实现干旱半干旱地区农业可持续发展的必然选择.     

干旱半干旱地区土壤矿物组成特征及其环境意义

对处于干旱、半干旱地区的甘肃省15个地点的灰钙土、栗钙土、黑垆土、灰褐土和黄绵土等不同类型土壤剖面进行了机械组成分析、矿物组成显微鉴定和粘土矿物X射线衍射分析.结果表明:土壤机械组成以粉砂为主,粘粒次之;栗钙土、灰钙土、黑钙土和灰褐土等于旱地区典型土壤中表层的粘粒质量分数相对较低,土壤原生矿物组成以石英为主,绿帘石等蚀变矿物质量分数较高,次生矿物含有较高的石膏和方解石等;粘土矿物主要为伊利石、绿泥石、高岭石和蒙脱石.土壤机械组成、矿物组成和粘土矿物组成表明:干旱、半干旱地区土壤为黄土母质,土壤形成条件为碱性环境、较弱的淋滤作用和干冷气候,近代强烈的风蚀作用(或沙尘暴)和大气污染对土壤有一定程度的改造.     

Modeling spatial and temporal variations in soil moisture in China

On the basis of station observations, an atmospheric field (ObsFC) was constructed for the Community Land Model version 3.5 (CLM3.5). The model (CLM3.5 driven with ObsFC, hereafter referred as to CLM3.5/ObsFC) was used to simulate soil moisture (SM) from 1951 to 2008 in China. The resulting SM was compared with in situ observations, remote-sensing data and estimations made by various land models, indicating that CLM3.5/ObsFC is capable of reproducing the temporospatial characteristics and long-term variation trends of SM over China. Using an in situ observation-based forcing field improves the simulation of SM. Analysis of SM simulated using CLM3.5/ObsFC shows that the overall spatial pattern of SM was characterized by a gradually decreasing and alternating distribution of arid-humid zones from the southeast to northwest. Regionally averaged SM was the driest over southern Xinjiang Province and western Inner Mongolia, while the most humid regions were located over the Northeast Plain, Jianghuai region and the Yangtze River basin. The long-term variation trends of SM were generally characterized by increases in arid and humid regions and decreases in semiarid regions. Moreover, the variation was relatively intense from the mid-1970s to the mid-1990s in the arid region. The time series was more stable in the humid region except for a period near 1970 and after the year 2003. A downward trend was most prominent in the semiarid region from the 1990s to the end of the time series. For 1951–2008, in the arid, semiarid and humid regions, the SM volume percentage changed by 2.35, −1.26 and 0.08, respectively. The variation trends and intensity remarkably differed among the different regions, with the most notable changes being over the arid and semiarid regions north of 35°N.     

The hydrological linkage of mountains and plains in the arid region of northwest China

Mountain regions supply a large amount of fresh water for the people in arid and semiarid regions, however, there is great uncertainty of the water quantification from mountains to lower areas. In order to assess the hydrological significance of mountains and the hydrological linkage of mountains and plains, the measured and simulated hydrological data of the arid region in northwest China were used in the present research which followed a catchment-based approach. Firstly, the Heihe River Basin, a well-documented area, was selected as a specific watershed to reveal the hydrological relationship between highlands (mountains) and lowlands (plains); and then, the significance and disproportion of mountain runoff of 8 river basins as cases in the arid region of northwest China were analyzed and compared following the above analysis. The results of the study showed that the proportion of mountain runoff in total basinal runoff (PMR) of most rivers is above 50%. The PMR are between 50%-95% in the rivers originated in the northern slope of the Tianshan Mountains where the aqueous vapor is relatively sufficient. And that, almost all the flow of the rivers originating from the Qilian Mountains, the southern slope of the Tianshan Mountains, and the northern slope of the Kunlun Mountains come from mountain regions. Also the PMR gradually increases from west to east in northwest China. The hydrological significance and disproportion of mountains water in the arid region of northwest China were given a systematic and thorough assessment, and the results could give potential guides for the scientific utilization of water resources in these regional areas for relieving the more and more serious shortage of water resources due to climate warming and population expansion.     

浅述宁夏北部地区土地沙化与沙漠化环境地质问题

宁夏北部地区地处干旱、半干旱气候地带,东、西、北三面被毛乌素沙漠、腾格里沙漠、乌兰布和沙漠所围限,受自然条件和人类经济活动等因素影响,土地沙化与沙漠化较为突出,为该地区最严重的环境地质问题之一。笔者通过对宁夏北部地区土地沙化与沙漠化环境地质问题的初步研究,简要分析了土地沙化与沙漠化的成因,提出了合理、经济而有效的防治对策,为振兴地方经济和可持续发展提供科学依据。     

Soil moisture-based study of the variability of dry-wet climate and climate zones in China

An ensemble soil moisture dataset was produced from 11 of 25 global climate model (GCM) simulations for two climate scenarios spanning 1900 to 2099; this dataset was based on an evaluation of the spatial correlation of means and trends in reference to soil moisture simulations conducted using the community land model driven by observed atmospheric forcing. Using the ensemble soil moisture index, we analyzed the dry-wet climate variability and the dynamics of the climate zone boundaries in China over this 199-year period. The results showed that soil moisture increased in the typically arid regions, but with insignificant trends in the humid regions; furthermore, the soil moisture exhibited strong oscillations with significant drought trends in the transition zones between arid and humid regions. The dynamics of climate zone boundaries indicated that the expansion of semiarid regions and the contraction of semi-humid regions are typical characteristics of the dry-wet climate variability for two scenarios in China. During the 20th century, the total area of semiarid regions expanded by 11.5% north of 30°N in China, compared to the average area for 1970–1999, but that of semi-humid regions decreased by approximately 9.8% in comparison to the average for the period of 1970–1999, even though the transfer area of the humid to the semi-humid regions was taken into account. For the 21st century, the dynamics exhibit similar trends of climate boundaries, but with greater intensity.     

植物根部水分再分配研究的区域特征及生态意义

在一些干旱、半干旱或季节性干旱地区,当植物的一部分根系处于较湿润的土壤层中,且土壤水势梯度合适的条件下,植物便会利用水分再分配来合理调配水分以缓解植物的干旱状况.植物根部水分再分配研究主要在有干湿季节交替或出现一段时间干旱的地区进行,这些地区包括萨瓦纳地区、具有热带或温带季风气候的地区以及具有地中海气候的地区.除此之外,在一些温带大陆性气候区也有部分研究.水分再分配现象使各土壤层中水分合理分配,上下运送的水分能够使植物根系保持湿润,从而延长和增强根系的活动性.再分配水分可提供植物白天蒸腾作用需要的部分水源,通过土壤-根系-大气系统促进水分运动,且释放到上层土壤中的水分还可以为周围邻近植物提供水分.由于养分一般储存在土壤的上层,水分的上下运动可以促进土壤中养分的循环以增强养分吸收、微生物过程,并提高养分的利用率.目前,水分再分配的研究区域越来越广泛,研究方法也趋于多样化和成熟.     

中国西北干旱区消除农村贫困人口对策

从自然环境特点和人口对自然资源的压力入手,分析西北干旱区,特别是位于陕西、甘肃、宁夏三省（区）黄土丘陵干旱半干旱山区贫困人口的致贫原因,针对性地提出消除贫困人口的途径和方法