Analysis of Water Resources Supply and Demand and Security of Water Resources Development in Irrigation Regions of the Middle Reaches of the Heihe River Basin, Northwest China

Based on the data for meteorology, hydrology, soil, planting, vegetation, and socio-economic development of the irrigation region in the middle reaches of the Heihe River basin, Northwest China, the model of balance of water supply and demand in the region was established, and the security of water resource was assessed, from which the results that the effects of unified management of water resources in the Heihe River basin between Gansu Province and Inner Mongolia on regional hydrology are significant with a decrease in water supply diverted from Heihe River and an increase in groundwater extracted. In addition, it was found that the groundwater level has been steadily decreasing due to over pumping and decrease in recharges. In present year （2003）, the volume of potential groundwater in the irrigation districts is far small because of the groundwater overdraft; even in the particular regions, there is no availability of groundwater resources for use. By 2003, water supply is not sufficient to meet the water demand in the different irrigation districts, the sustainable development and utilization of water resources are not secured, and the water supply crisis occurs in Pingchuan irrigation district. Achieving water security for the sustainable development of society, agriculture, economy, industry, and livelihoods while maintaining or improving the abilities of the management and planning of water resources, determining of the reasonable percentage between water supply and groundwater utilization and water saving in agricultural irrigation are taken into account. If this does not occur, it is feared that the present performance of water development and planning may further aggravate the problem of scarcities of water resources and further damage the fragile ecological system.

Tree-ring-based reconstruction of temperature variability(1445–2011) for the upper reaches of the Heihe River Basin, Northwest China

Long-term temperature variability has significant effects on runoff into the upper reaches of inland rivers. This paper developed a tree-ring chronology of Qilian juniper (Sabina przewalskii Kom.) from the upper tree-line of the middle Qilian Mountains within the upper reaches of Heihe River Basin, Northwest China for a long-term reconstruction of temperature at the study site. In this paper, tree-ring chronology was used to examine climate-growth associations considering local climate data obtained from Qilian Meteorological Station. The results showed that temperatures correlated extremely well with standardized growth indices of trees (r=0.564, P<0.001). Tree-ring chronology was highest correlated with annual mean temperature (r=0.641, P<0.0001). Annual mean temperature which spans the period of 1445–2011 was reconstructed and explained 57.8% of the inter-annual to decadal temperature variance at the regional scale for the period 1961–2011. Spatial correlation patterns revealed that reconstructed temperature data and gridded temperature data had a significant correlation on a regional scale, indicating that the reconstruction represents climatic variations for an extended area surrounding the sampling sites. Analysis of the temperature reconstruction indicated that major cold periods occurred during the periods of 1450s–1480s, 1590s–1770s, 1810s–1890s, 1920s–1940s, and 1960s–1970s. Warm intervals occurred during 1490s–1580s, 1780s–1800s, 1900s–1910s, 1950s, and 1980s to present. The coldest 100-year and decadal periods occurred from 1490s–1580s and 1780s–1800s, respectively, while the warmest 100 years within the studied time period was the 20th century. Colder events and intervals coincided with wet or moist conditions in and near the study region. The reconstructed temperature agreed well with other temperature series reconstructed across the surrounding areas, demonstrating that this reconstructed temperature could be used to evaluate regional climate change. Compared to the tree-ring reconstructed temperature from nearby regions and records of glacier fluctuations from the surrounding high mountains, this reconstruction was reliable, and could aid in the evaluation of regional climate variability. Spectral analyses suggested that the reconstructed annual mean temperature variation may be related to large-scale atmospheric–oceanic variability such as the solar activity, Pacific Decadal Oscillation (PDO) and El Ni?o–Southern Oscillation (ENSO).

Water accounting for conjunctive groundwater and surface water irrigation sources: A case study in the middle Heihe River Basin of arid northwestern China

Oases in arid northwestern China play a significant role in the region＇s economic stability and development. Overex- ploitation of the region＇s water resources has led to serious environmental consequences. In oases, irrigated agriculture is the primary consumer of water, but water shortages resulting from dramatically growing human needs have become a bottleneck for regional sustainable development, making effective management of the limited available water critical. Effective strategies must be formulated to increase agricultural productivity while reducing its environmental impacts. To support the development of such strategies, water use patterns were analyzed during the 2007 and 2008 growing seasons, from May to early October, to identify opportunities for improving water management using the Mold- en-Sakthivadivel water-accounting method, which combines groundwater and surface water into a single domain and can provide a good estimate of the uses, depletion, and productivity of water in a water basin context. The study area lies in Linze County, Gansu Province, China. In the study area, the inflow water resources consist of irrigation, precipita- tion, and soil water, which accounted for 89.3%, 8.9%, and 1.8% of the total in 2007, and 89.3%, 4.8%, and 5.9% in 2008, respectively. The irrigation depends heavily on groundwater, which accounted for 82.1% and 83.6% of the total irrigation water in 2007 and 2008, respectively. In 2007 and 2008, deep percolation accounted for 50.1% and 47.9% of the water outflow, respectively, with corresponding depleted fractions of 0.51 and 0.55, respectively. For the irrigation district as a whole, the water productivity was only 1.37 CNY/m^3. To significantly increase crop water productivity and prevent depletion of the region＇s groundwater aquifer, it will be necessary to reduce the amount of water used for ir- rigation. Several water-saving agricultural practices are discussed and recommended.

Relationship between sand-dust weather and water dynamics of desert areas in the middle reaches of Heihe River

Sand-dust weather has become an international social-environmental issue of common concern, and constitutes a serious threat to human lives and economic development. In order to explore the responses of natural desert sand and dust to the dynamics of water in desertification, we extracted long-term monitoring data related to precipitation, soil water, groundwater, and sand-dust weather. These data originated from the test stations for desertification control in desert areas of the middle reaches of the Heihe River. We used an algorithm of characteristic parameters, correlations, and multiple regression analysis to establish a regression model for the duration of sand-dust weather. The response char-acteristics of the natural desert sand and dust and changes of the water inter-annual and annual variance were also examined. Our results showed： （1） From 2006 to 2014 the frequency, duration, and volatility trends of sand-dust weather obviously increased, but the change amplitudes of precipitation, soil water, and groundwater level grew smaller. （2） In the vegetative growth seasons from March to November, the annual variance rates of the soil moisture content in each of four studied layers of soil samples were similar, and the changes in the frequency and duration of sand-dust weather were similar. （3） Our new regression equation for the duration of sand-dust weather passed the R test, F test, and t test. By this regression model we could predict the duration of sand-dust weather with an accuracy of 42.9%. This study can thus provide technological support and reference data for water resource management and re-search regarding sand-dust weather mechanisms.

Measurement on the Harmony Coefficient of Agro-eco-economic System in the Arid Region

On the basis of the present research progress of ecological agriculture,we take Minle County and Linze County located in the middle reaches of Heihe River as the typical research units.Based on the rural social and economic data during the period of 2000-2010,theory and method of mathematical statistics are used to establish the measure theory and model of agro-eco-economic system harmony coefficient,including efficacy function,function of harmony coefficient,harmony coefficient and level of harmony coefficient.Based on the actual situation of research region,evaluation indicator system of agro-eco-economic system is established and measurement is carried out.Results show that the regional agro-eco-economic system in research region was in a serious imbalance in 2000-2013.The harmony coefficient of Minle showed a slight rise from 2000 to 2004,and then presented a fluctuating decline.Its rank of harmony coefficient experienced serious imbalance-extreme imbalance-moderate imbalance-low imbalance-serious imbalance-high imbalance.At the same time,the similar tendency happened in Linze County.The measuring results of subsystem in 2000-2013 further indicated that except that the harmony coefficient of economic subsystem in Minle County and Linze County was moderate and high,the ecological subsystem was at Level II and Level III,and social subsystem was at Level IV and Level III,in high and low imbalance status.Finally,several recommendations were put forward for optimizing agro-eco-economic system.

Characteristics of dry-wet abrupt alternation events in the middle and lower reaches of the Yangtze River Basin and the relationship with ENSO

During recent decades, more frequent flood-drought alternations have been seen in China as a result of global climate change and intensive human activities, which have sig- nificant implications on water and food security. To better identify the characteristics of flood-drought alternations, we proposed a modified dry-wet abrupt alternation index （DWAAI） and applied the new method in the middle and lower reaches of the Yangtze River Basin （YRB-ML） to analyze the long-term spatio-temporal characteristics of dry-wet abrupt alterna- tion （DWAA） events based on the daily precipitation observations at 75 rainfall stations in summer from 1960 to 2015. We found that the DWAA events have been spreading in the study area with higher frequency and intensity since 1960. In particular, the DWAA events mainly occurred in May and June in the northwest of the YRB-ML, including Hanjiang River Basin, the middle reaches of the YRB, north of Dongting Lake and northwest of Poyang Lake. In addition, we also analyzed the impact of El Nifio Southern Oscillation （ENSO） on DWAA events in the YRB-ML. The results showed that around 41.04% of DWAA events occurred during the declining stages of La Nifia or within the subsequent 8 months after La Nina, which implies that La Nina events could be predictive signals of DWAA events. Besides, significant negative correlations have been found between the modified DWAAI values of all the rainfall stations and the sea surface temperature anomalies in the Nino3.4 region within the 6 months prior to the DWAA events, particularly for the Poyang Lake watershed and the middle reaches of the YRB. This study has significant implications on the flood and drought control and water resources management in the YRB-ML under the challenge of future climate change.

Zircon U-Pb dating and Lu-Hf isotope study of intermediate-mafic sub-volcanic and intrusive rocks in the Lishui Basin in the middle and lower reaches of Yangtze River

Eight Mesozoic sub-volcanic and intrusive rocks in the Lishui Basin have been selected for zircon U-Pb dating and Lu-Hf isotopic analysis. The Laohutou, Datongshan,Daweizhuang, Yeshanao, Yanwaqiao, Xibeishan, Changshantou and Jianshan porphyrites yield concordant early Cretaceous ages of 130.5 ± 1.6 Ma, 136.0 ± 3.4 Ma, 132.7 ±2.7 Ma, 127.0 ± 1.9 Ma, 129.4 ± 1.7 Ma, 133.2 ± 2.1 Ma,131.1 ± 2.3 Ma and 127.4 ± 1.8 Ma, respectively. Zircon eHf(t) values for these rocks range from-3.54 to-9.11, mostly between-3.54 and-5.93, suggesting sources similar to those for coeval igneous rocks in other volcanic basins along the middle and lower reaches of Yangtze River. Considering the geochemical characteristics of coeval magmatic rocks in the middle and lower reaches of Yangtze River and its adjacent areas, this paper proposes a model of slab rollback to explain the Mesozoic magmatism in the east-central part of China continent. In the middle-late Jurassic to early Cretaceous(170–135 Ma), the Pacific plate started to subduct beneath the Eurasian continent, producing a compressive tectonic setting,and magmatism progressed from coast to the inland. The magmas of this period were derived mostly from partial melting of ancient crust. After *135 Ma, the subduction weakened, and the rollback of the subducted Pacific plate produced an extensional environment. This led to the formation of volcanic basins, the partial melting of enriched mantle sources and less ancient crust, and the intrusion of voluminous intermediate-mafic igneous rocks.

黑河中游绿洲边缘三种景观类型土壤水分动态特征及影响因素

土壤水分对干旱区旱生植物的生长发育必不可少,决定了旱生植物群落的演替动态和方向。探究黑河中游绿洲边缘不同景观类型的土壤水分动态特征,制定切实有效、科学合理的防风固沙措施,对于阻止荒漠化进程显得尤为重要。本文以黑河中游绿洲边缘的防护林、荒漠-绿洲过渡带和荒漠三种景观类型为研究对象,采用HYDRUS-2D模型模拟、LSD分析法、Pearson相关性分析等方法,研究三种不同景观类型土壤水分动态特征及影响因素。结果表明:(1)土壤体积含水量的RMSE为0.002~0.006 cm^(3)·cm^(-3),MRE为4.22%~5.20%,R^(2)为0.725~0.967,模拟结果与实测数据具有较高的吻合度,HYDRUS-2D模型可用于本研究区土壤水分动态的模拟研究。(2)防护林和荒漠-绿洲过渡带景观的土壤体积含水量随土层深度增加呈现出先增大后减小的变化趋势,荒漠景观则呈现出先减小后增大的变化趋势。(3)有效降水对土壤体积含水量动态变化起决定性作用,9.5 mm以上的降水量可以在短期内显著提高土壤水分含量和入渗深度,荒漠景观降水后的各时段土壤水分入渗深度高于防护林景观和荒漠-绿洲过渡带景观。(4)三种景观类型的土壤体积含水量与降水、蒸散发、容重、土壤颗粒组成、土壤持水性能等因素有关,且表现出不同程度的显著相关(P<0.01),其中,降水、黏粉粒含量与土壤体积含水量呈显著正相关,容重、砂粒含量与土壤体积含水量呈显著负相关性。因此,研究区栽植防风固沙灌木可以增加土壤黏粉粒含量,提高土壤收集利用雨水的能力,减缓入渗作用的进程,从而对土壤持水性能产生积极影响。

黄河流域中游3A级及以上山地景区空间特征及形成机制

为了促进区域经济发展、改善黄河流域生态环境质量,基于景区兴趣点(point of interest,POI)数据,采用核密度估计、标准差椭圆、地理联系率和空间叠加分析等方法,探究黄河流域中游170个3A级及以上(以下简称“3A级以上”)山地景区的空间分布特点及影响因素.结果表明:①黄河流域中游3A级以上山地景区集中分布在晋、陕、豫三省,景区密度大.3A级山地景区高密度区主要分布在豫北、豫南、晋东南;4A级山地景区呈向右旋转90°的“Y”型分布;5A级山地景区主要集中在晋、陕、豫交界处,组团状分布,由东北向西南展布.②自然地理环境方面,3A级以上山地景区主要分布在海拔300~1200 m处,坡度为15°~45°,偏南坡.河流水系、植被指数、空气质量对景区分布的影响效果显著.③社会经济环境方面,交通区位、固定资产投资、旅游收入和文化遗产禀赋是景区发展的重要影响因素.

长江中下游降雨侵蚀力时空变化及其与植被覆盖的关系

充分掌握大尺度流域降雨侵蚀力的时空变化特征对流域水土保持、防洪减灾和生态环境保护至关重要。基于长江中下游的119个气象站点57a逐日降雨资料,通过Xie模型计算各站降雨侵蚀力,使用旋转经验正交函数(REOF)法对降雨侵蚀力进行区域划分;结合Mann-Kendal检验、重标极差(R/S)法和相关性分析方法分析长江中下游降雨侵蚀力的时空变化特征,并揭示其与植被覆盖度之间的关系。结果表明:(1)长江中下游降雨侵蚀力整体呈上升趋势,年均降雨侵蚀力为5643MJ mm hm^(-2)h^(-1)。(2)不同季节降雨侵蚀力空间分布存在差异。冷季降雨侵蚀力空间分布不均,高值区主要集中在流域的西部和东北部,而暖季降雨侵蚀力则表现为以江西省为中心沿西北方向递减的空间分布格局,最大值和最小值出现在鄱阳湖环湖区(III区)和长江干流武汉以下段及太湖水系(IV区)。(3)长江中下游相邻地理分区间降雨侵蚀力变化速率差异较大,降雨侵蚀力区域性差异显著。其中III区、湘江及赣江流域(I区)和IV区年均降雨侵蚀力呈显著增长趋势(P<0.05)且未来将保持该趋势,为水土保持重点关注区域。(4)研究所发现的长江中下游水土保持重点关注区域的降雨侵蚀力与植被覆盖度存在负相关。但值得注意的是I区在冷季呈现正相关,而且其中的湘江上游流域出现显著正相关。研究表明降雨侵蚀力是影响地表侵蚀过程的关键因素,侵蚀性降水会影响植被覆盖情况,进而影响地表的侵蚀过程。因此在重点关注高降雨侵蚀力地区的同时还需加强植被保护工作。研究结果可为长江中下游区域水土保持及生态环境保护工作提供科学依据。

基于SWAT模型的黑河中游蓝绿水安全时空变化分析

蓝水和绿水是淡水资源循环的两个组成部分,反映了人类活动和生态系统可利用水资源,用来评估区域水资源的安全状况,优化区域水资源管理。然而,目前对于同时揭示蓝绿水资源安全之间潜在联系的空间规律的研究还较为缺乏。地处西北内陆干旱区的黑河中游的生态环境保护和社会经济发展之间的用水矛盾日益加剧,导致水资源供需关系渐趋紧张,影响区域可持续发展。以黑河中游为研究区,采取多源地理数据,基于SWAT模型分析了黑河中游2000—2020年期间子流域尺度上蓝水和绿水资源的可用性,进而结合用水需求,定量评估了蓝水资源和绿水资源安全的时空变化。结果表明:(1)率定期和验证期R2与NSE均>0.7,说明观测径流与模拟径流之间一致性较好,构建的SWAT模型在蓝绿水安全研究中较为可靠。(2)黑河中游的年平均绿水资源量是蓝水资源量的4倍,是该地区的主要水资源。从空间分布来看,蓝绿水资源的空间分布具有较大的差异性,蓝水资源大多分布于南部林草地和干流两侧的农田灌区,而绿水从南部向北部呈现递减趋势(2)由于水资源供给和需求的空间不匹配,蓝水资源的安全性较低,不安全地区位于中部农田集中区,而绿水资源安全性较高且整体较为稳定,空间差异不大。研究结果可为区域水资源持续管理提供参考。

黄河流域中游地下水干旱演变规律及其对植被变化的响应

【目的】明确黄河流域中游地下水干旱时空演变规律。【方法】基于GRACE/GRACE-FO卫星数据和GLDAS数据计算标准化地下水干旱指数SGDI,利用改进的Mann-Kendall趋势检验研究和识别黄河流域中游的地下水干旱时空演变规律,利用Spearman相关分析研究地下水干旱对植被变化的响应。【结果】①黄河流域中游地下水储量异常以-0.027mm/d的速率变化,时空分布极不均匀。②地下水干旱时间上分布不均匀,在2018年之后发生中度甚至重度的地下水干旱,且SGDI的Theil-Sen变化率为-4.10×10^(-4)/d,未来地下水干旱有显著的增加趋势。③地下水干旱空间上分布不均匀,干旱增加趋势面积占比为63.02%,未来干旱恶化趋势增加,出现自西南向东北加剧现象。④植被变化对地下水干旱的驱动作用不显著。【结论】黄河流域中游地下水干旱较严重,地下水干旱对植被变化存在不显著的响应。

长江中下游流域实际蒸散发演变特征及驱动机制

为了更好地了解长江中下游6个子流域蒸散发量时空演变特征,以及气候和下垫面因子改变对蒸散发量变化的影响,基于GRACE重力卫星观测数据和水量平衡法重建了长江中下游6个子流域实际蒸散发ET序列,评估并融合了3种ET数据集,获得1992—2015年高精度的逐月蒸散发量,分析了6个子流域蒸散发量年值和季节值的变化趋势,引入土地利用程度综合指数La,基于通径分析法定量评估了气候和下垫面因子对各子流域蒸散发量变化的直接和间接影响。结果表明:①3种数据集在长江中下游流域的适用性较好,基于最小二乘权重法的数据融合方法减小了ETrecon与ETNOAH、ETGLEAM的平均差和均方根误差,减小了ETNOAH、ETCR的标准差。②长江中下游流域多年平均蒸散发量为728.7 mm,空间上自西北向东南递增;6个子流域不同季节的蒸散发量均呈升高趋势,其中春、夏季的增幅最大。③各子流域年蒸散发量增加主要由La增强和气温升高所致,气温、La和植被覆盖率等要素的间接作用致使太湖流域风速降低对蒸散发量的影响从正向变为负向。④气温升高促进了NDVI对6个子流域春、夏季蒸散发量增加的正向效应,太湖流域、长江中游和下游干流区秋、冬季降水的增加削弱了辐射降低对蒸散发量变化的作用,而风速上升是洞庭湖流域、中游干流区冬季蒸散发量微弱增加的主导因素。研究结果将为长江中下游流域水资源管理、干旱预测和生态功能评估等研究提供理论基础与科学依据。

黑河中游耕地变化与节水灌溉对地表耗水与地下水的影响

为探究黑河中游耕地面积变化与节水灌溉影响下地表水耗水及地下水动态演变特征,基于1985—2022年黑河莺落峡、正义峡水文站实测径流量月数据和中游地区49眼地下水观测井埋深月数据,结合对节水灌溉的实地调研结果,利用统计分析等方法,分析了地表水耗水和地下水埋深对耕地面积变化与节水灌溉的响应。结果表明:耕地面积变化、节水灌溉和水量统一调度多重影响下,黑河中游地表水耗水量略有下降;黑河中游地下水埋深总体呈增大趋势,扩耕较大的大满灌区东南部与东北部及友联灌区中部地下水埋深明显增大;不同灌溉方式对地下水埋深也有较大影响,河灌区地下水埋深随地表水入渗补给量变化,井灌区和混灌区地下水埋深随地下水开采量变化。

“流域-人-歌”三重互联:对长江中下游流域民歌的考察

基于对长江中下游民歌的沿江调查及研究,从“流域-人-歌”三者关系出发,可以发现作为自然区域、作为文化“通道”和“界限”以及作为经济带三种视域下,流域-人-歌三者之间存在互联。随着现代社会经济的发展,传统民歌的存承方式也在发生改变。在国家大力建设长江经济带背景下,应立足于新兴的流域(水域)音乐文化研究,加强对长江流域民歌文化带的保护,进而打造良好的长江经济带文化生态。

东江流域中下游典型土壤分类及养分特征分析——以惠城区为例

以惠城区为例,对东江流域中下游典型土壤进行分类,通过采集1 619个土壤样品进行化验分析,研究东江流域中下游典型土壤养分特征。结果表明,惠城区耕地土壤有机质、全氮含量均属中等偏上水平;青泥格田、花岗岩红泥田等土属有机质含量较高,而乌泥底田、砂页岩赤红地、红色砂页岩赤红地等土属含量较低;青泥格田、花岗岩红泥田、石质土、花岗岩红黄泥田等土属全氮含量较高,而乌泥底田、砂页岩赤红地等土属含量较低;土壤全氮含量与有机质含量之间呈极显著的直线相关关系,回归方程为Y=0.039 8X+0.376 9,相关系数为0.65;有机质、全氮含量累积基本符合不同分类土壤形成规律。土壤碱解氮含量总体上属中等偏上水平,平均含量水平达到三级标准;土壤有效磷含量总体上属上中等水平,平均含量水平达到一级标准;土壤速效钾、缓效钾含量处于中等偏下水平。不同土属类型的土壤碱解氮、有效磷、速效钾、缓效钾含量差异均较明显,没有明显规律可循,主要是受人为施用化肥影响较大。

基于讨赖河中下游流域生态环境保护与可持续发展策略

甘肃位于中国西北内陆地区,其气候特征干旱,降水量稀少,水资源匮乏,处于干旱区的讨赖河流域生态环境十分脆弱。为缓解当前水资源利用中存在的问题,保护生态环境,文章分析了讨赖河中下游流域生态环境的主要问题及成因,提出了相应的治理措施,为该地区生态保护与经济社会可持续发展提供了科学的决策帮助。

黑河流域中游沙荒地元宝枫引种栽培试验研究

元宝枫系一种适应力较强的生态经济型树种。采用客土造林法,在黑河流域中游沙荒地分别栽植陕西杨凌、河南平顶山、山东聊城引进的元宝枫苗木,试验研究表明,1)不同种源的苗木栽植后,栽植成活率最高的是陕西杨凌,为69.3%,分别较山东聊城和河南平顶山高27.2%和32.6%;栽植2年生的元宝枫苗木枝条生长量最大的是陕西杨凌的苗木,枝条平均生长量为108.8cm,分别较山东聊城和河南平顶山枝条平均生长量高16.98%和37.37%;第2年新梢生长量达78.8cm,分别比山东聊城和河南平顶山高34.47%和72.05%;胸径均生长量分别高7.56%和12.04%;2)元宝枫苗木在黑河流域中游沙荒地3月20—25日栽植成活率最高,带土球栽植的较4月20—25日高19.9%,裸根苗高26.3%,胸径生长量均增粗5.81%,新生枝条均生长量提高43.7%;3)带状客土整地后栽植陕西杨凌、河南平顶山和山东聊城的苗木,其成活率分别较局部客土整地提升28.49%、23.61%和25.15%,2年生胸径均生长量增大14.41%、13.57%和14.22%,2年生新生枝条均生长量提高67.9%、43.1%和49.6%。研究成果为元宝枫在黑河流域中游沙荒地引种栽培提供技术支撑。

黑河中游荒漠化地区植被动态变化及其自然驱动因素分析

对2019—2023年黑河中游4个类型荒漠区样地植被生长状况和监测区气温、空气湿度、蒸发量、土壤含水率等自然因子进行监测,分析监测区植被动态变化及其与自然驱动因素的相关性。结果表明:降水量大、空气湿度大、蒸发量小、风速低的年份和月份,植被状况相对较好,盖度、高度、密度和生物量都比较高;相反,降水量小、空气湿度小、蒸发量大、风速高的年份和月份,植被状况相对较差。从年际变化趋势看,各样地植被变化规律很不稳定,总体来说由于降水、气温、空气湿度等关键气象因子数据的不稳定性,植被变化规律也表现出很大的不确定性。从月际数据分析,各样地均表现出5月、6月、7月、8月和9月盖度、生物量、高度较大的特性。4个样地之间植被状况存在很大的差异性,说明气象因子对不同类型荒漠化土地植被的影响是不同的。单从2023年数据看,4个样地植被状况和往年纵向相比有明显长势变弱的趋势,2023年出现持续高温、少雨现象,植被生长量下降,一些植物受高温、干旱影响而死亡,造成植被盖度降低。5年监测数据显示,土壤含水率不论年际还是月际数据变化都没有明显的规律性,只随降水量和蒸发量的变化而变化;土壤含水率明显降低的年份和月份,植被生长也相应缓慢,植被高度、盖度、密度和生物量均受到不同程度的影响。各类数据均表明,样地2土壤含水率明显高于其他3个样地,说明盐碱区(沼泽草地)土地的持水能力要好于其他土地。

黑河中游沙漠-绿洲过渡带起沙风风况及输沙势特征——以临泽县为例

基于甘肃临泽农田生态系统国家野外科学观测研究站气象观测数据,在分析黑河中游沙漠-绿洲过渡带的起沙风风况和输沙势特征变化情况的基础上,评估了区域风能状况。结果表明:研究区年均起沙风风速为6.12 m/s,年均起沙风频率为5.57%,最大风速为23.3 m/s;研究区年起沙风向主要以偏东风(NNE、NE、ENE、E)和偏西风(WNW、NW、W)为主;研究区年输沙势(DP)和年合成输沙势(RDP)分别为18.88 VU和6.10 VU,属于低风能环境;年方向变率指数(RDP/DP)为0.32,属于中比率的钝双峰或锐双峰型风况;年合成输沙势方向(RDD)267.05°,为W方向,表明黑河中游沙漠-绿洲过渡带沙物质主要朝西方向输移;风能环境在春季最大,在这期间可通过适当的防护措施截留沙物质,进而减少风沙灾害的发生。