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1.
为研究实际水利条件下农业干旱的发生规律,简化农业干旱事件的评估方法,提出基于区域农业用水量的干旱重现期计算方法。通过构建农业用水量距平百分率干旱指标WA,在基于降雨量距平百分率干旱指标PA识别干旱事件的基础上,提取WA干旱指标下的干旱历时和干旱烈度特征变量,并根据以PA为干旱指标的干旱烈度频率分布曲线FS（x）和干旱历时频率分布曲线FD（x）,运用Copula的简化方法计算基于WA的干旱事件重现期T,最后结合基于PA的干旱事件重现期T0,回归分析出T与T0间关系的计算公式。选取干旱灾害影响严重的亳州市为实证区域开展应用研究,计算得到1975-2007年各场干旱事件的T0和T以及T0与T的经验关系式。结果表明:T比T0更合理地反映区域农业实际受旱状况,重现期T0和T间存在高度的相关关系,采用T的回归方程可简化计算考虑区域实际抗旱能力下的干旱事件重现期,在区域防旱减灾实践中具有推广应用价值。 相似文献
2.
NDVI dynamic changes and their relationship with meteorological factors and soil moisture 总被引：1，自引：0，他引：1
Hongxue Zhang Jianxia Chang Lianpeng Zhang Yimin Wang Yunyun Li Xiaoyu Wang 《Environmental Earth Sciences》2018,77(16):582
Normalized difference vegetation index (NDVI) is an important indicator for measuring vegetation coverage, which is of great significance for evaluating vegetation dynamics and vegetation restoration. It can clearly analyze the suitable growth condition of vegetation by studying the relationship between meteorological factors, soil moisture and NDVI. Based on MODIS/NDVI data, the spatio-temporal characteristics of vegetation coverage in the Weihe River Basin (WRB) were analyzed by the trend analysis method. The relationship of NDVI with meteorological factors and NDVI with soil moisture simulated by the soil and water assessment tool (SWAT) model was analyzed in this paper. The results show that NDVI values gradually change with an increase from north to south in the WRB. The maximum of the average monthly NDVI is 0.702 (August) and the minimum is 0.288 in February from 2000 to 2015. The results of the seven grades of NDVI trend line slope indicate that the improvement area of vegetation coverage accounts for 30.93% of the total basin, and the degradation area and basically unchanged area account for 23% and 42.9%, respectively. The annual mean soil moisture is 19.37% in the WRB. There was a strong correlation between NDVI and precipitation, temperature, evaporation and soil moisture, and the correlation coefficients were 0.78, 0.89, 0.71 and 0.65, respectively. The ranges of the most suitable growth conditions for vegetation are 80–145 mm (precipitation), 13–23 °C (temperature), 94–144 mm (evaporation) and 25–33% (soil moisture), respectively. 相似文献
3.
为揭示喀斯特石漠化治理示范区植被覆盖变化以及气候因子对植被覆盖变化的影响,利用2006—2015年Landsat 30 m/16 d分辨率影像数据,采用最大合成法、NDVI差值指数和相关、偏相关分析法,系统分析示范区归一化植被指数的时空变化特征及其与气候因子的关系。结果表明:(1)2006—2015年最大NDVI平均值为0.39,NDVI较高覆盖区域在示范区南北边界,而较低覆区域以花江南岸为主;(2)2006年以来示范区极低(-1.210)、低(-0.669)和中等(-0.729)植被覆盖度呈减少趋势,高(1.359)和极高(1.247)植被覆盖度增加,整体上呈显著增加趋势;(3)本月NDVI与本月、上月、上上月降雨量和气温的相关性均通过显著水平0.05检验,且本月NDVI与本月降雨量相关性高于本月气温(RNDVI降雨 =0.782),本月NDVI与上月气温相关性高于上月降雨量(RNDVI气温 =0.771);(4)在月尺度上,示范区植被生长对降雨量无滞后期,而对气温存在1个月的滞后期。 相似文献
4.
典型冰冻圈地区植被变化对人类活动的响应研究
——以祁连山为例 总被引：1，自引：1，他引：0
在全球气候变化、种植业结构调整等背景下,亟需对祁连山区的植被展开长期有效的监测和持续研究。基于2000-2017年分辨率为250 m的MODIS数据,采用Mann-Kendall时间序列非参数估计模型、相关分析等方法,分析了祁连山区生长季NDVI与植被盖度的时空变化特征及其与气候因子的相关性,并从正反两方面就人类活动对对植被的影响做了讨论,得出结论如下：（1）从东向西祁连山年平均NDVI整体上逐渐减小,NDVI随海拔升高呈先增大后减小的特征,NDVI最大的区域分布在海拔2 700~2 900 m的范围内;（2）祁连山区域内NDVI显著减小的区域占祁连山总面积的0.6%,而显著增加的区域占总面积的33.6%,植被呈现出整体向好,局部退化的趋势;（3）2000-2017年,林地、草地和其他土地利用区的植被盖度分别以0.0029、0.0026和0.0004的速率增加,工矿用地的覆盖度以0.0112的速率在减少,反映出工矿业开发活动是造成植被盖度下降的主要因子;（4）植树造林区植被NDVI以0.0455的速度增加,而工程实施和矿产开发区NDVI以0.0125速度降低,表明人类活动是导致植被群落变化的主要因素之一。 相似文献
5.
黄河源区气候对径流的影响分析 总被引：3，自引：0，他引：3
根据对降水响应速度的快慢,径流又可分为直接径流和基流。基流一般定义为河川径流中来自于地下蓄水或者其他延迟水源的成分,代表地下水出流;直接径流表示对降水事件的直接响应。从这一思路出发,文中在分析降水到总径流、直接径流和基流的转化率的基础上分析了气候变化对径流的影响。研究发现,黄河源区的径流系数随降水量的增加而增大,随气温升高而降低;径流随着降水的增加而增加。20世纪90年代降水减少和气温的大幅度升高是黄河源区径流减少的重要原因。区间子流域分析表明,不同的子流域气温和降水对径流的影响不同,在吉迈以上区间,年气温比较低,气温是影响径流系数的主要因子,径流随着气温的升高而降低,降水对径流的影响比较小;在吉迈—玛曲区间,直接径流量/降水量主要受降水的影响,总径流量/降水量、基流量/降水量随降水增加而升高,随气温升高而降低。总径流和基流随降水的增加而增大,随气温的升高而减少;在玛曲—唐乃亥区间,径流系数随着降水量的增加而增加,直接径流量/降水量随气温的升高而降低,降水是径流的主要影响因素。 相似文献
6.
环境变化下水文干旱研究是水科学研究领域的热点问题之一。根据荆南三口河系1956-2017年5个水文站和22个气象站实测数据,采用标准化径流指数（Standardized Runoff Index,SRI）、降水-径流多元非线性模型、累积量斜率变化率比较法辅以Mann-Kendall检验法等方法,分析环境变化前后荆南三口河系62年水文干旱演变特征,并定量分解气候变化（降水量、蒸发量）和人类活动对径流量衰减的影响。结果表明：荆南三口河系整体干旱频率较高,变化期干旱事件发生频次多且等级高,多尺度干旱平均频率达42.96%,稳定期极少出现干旱现象;三口地区年径流量、年蒸发量在长时间序列上均呈下降趋势,年降水量较为稳定,年径流量检验的突变年份为1970年、1985年和2003年;人类活动是促使三口河系年径流量逐渐衰减的主要原因,1971-1985年、1986-2003年和2004-2017年三个时期人类活动对径流量变化（水文干旱演变）影响的贡献率依次为91.14%、103.73%、78.33%。 相似文献
7.
Assessing vegetation dynamics and their relationships with climatic variability in Heilongjiang province, northeast China 总被引：2，自引：1，他引：1
Wenbin Liu Tijiu Cai Cunyong Ju Guobin Fu Yuefeng Yao Xueqing Cui 《Environmental Earth Sciences》2011,64(8):2013-2024
In this study, the vegetation dynamics in Heilongjiang province and their relationships with climate variability were assessed
using normalized difference vegetation index (NDVI) and meteorological datasets from 1981 to 2003. The conclusions from our
results are as follows: (1) After 1981, vegetation cover, as indicated by the NDVI, exhibited an insignificant increasing
tendency. However, the inter-annual variations of the NDVI showed apparent spatial differentiations. (2) The inter-annual
changes of the NDVI were different from season to season. The spring and autumn NDVI values increased, while the summer and
winter NDVI decreased. (3) The annual NDVI was significantly correlated with precipitation. Thus, as compared to temperature,
precipitation was the dominant climatic factor affecting the vegetation dynamics in Heilongjiang province. (4) The trend in
the NDVI showed a marked homogeneity corresponding to regional and seasonal variations in climate. Additionally, land use
changes also play an important role in influencing the NDVI trends over some regions. All of these findings will enrich our
knowledge of the natural forces that impact the stability of boreal ecosystems and provide a scientific basis for the environmental
management in Heilongjiang province in response to climate change and human activities. 相似文献
8.
Iraq, the land of two rivers, has a history that extends back millennia and is the subject of much archaeological research. However, little environmental research has been carried out, and as such relatively little is known about the interaction between Iraq’s vegetation and climate. This research serves to fill this knowledge gap by investigating the relationship between the Normalized Difference Vegetation Index (NDVI) and two climatic factors (precipitation and air temperature) over the last decade. The precipitation and air temperature datasets are from the Water and Global Change Forcing Data ERA-Interim (WFDEI), and the NDVI dataset was extracted from the Moderate Resolution Imaging Spectroradiometer (MODIS) at 250 m spatial resolution and 16 day temporal resolution. Three different climatic regions in Iraq, Sulaymaniyah, Wasit, and Basrah, were selected for the period of 2001–2015. This is the first study to compare these regions in Iraq, and one of only a few investigating vegetation’s relationship with multiple climatic factors, including precipitation and air temperature, particularly in a semi-arid region. The interannual, intra-annual and seasonal variability for each region is analysed to compare the different responses of vegetation growth to climatic factors. Correlations between NDVI and climatic factors are also included. Plotting annual cycles of NDVI and precipitation reveals a coherent onset, fluctuation (peak and decline), with a time lag of 4 months for Sulaymaniyah and Wasit (while for the Basrah region, high temperatures and a short rainy season was observed). The correlation coefficients between NDVI and precipitation are relatively high, especially in Sulaymaniyah, and the largest positive correlation was (0.8635) with a time lag of 4 months. The phenological transition points range between 3 and 4 month time lag; this corresponds to the duration of maturity of the vegetation. However, when correlated with air temperature, NDVI experiences an inverse relationship, although not as strong as that of NDVI and precipitation; the highest negative correlation was observed in Wasit with a time lag of 2 months (? 0.7562). The results showed that there is a similarity between temporal patterns of NDVI and precipitation. This similarity is stronger than that of NDVI and air temperature, so it can be concluded that NDVI is a sensitive indicator of the inter-annual variability of precipitation and that precipitation constitutes the primary factor in germination while the air temperature acts with a lesser effect. 相似文献
9.
格尔木河流域植被指数时空分布及其影响因素研究 总被引：2，自引：0，他引：2
格尔木河流域气候干旱少雨,生态环境较脆弱,植被动态对其生态环境保护具有重要意义。基于连续序列的MODIS NDVI数据,分析了格尔木河流域植被指数时空分布及其影响因素。结果表明:研究区NDVI平均值总体较小,主要在0.10～0.12间波动,但呈增大趋势。区内植被改善区分布在格尔木市东、西两侧,基本不变区为荒漠地区,植被退化区分布在北部盐湖区。区内裸土的面积逐渐减小,低覆盖率和高覆盖率植被的面积逐渐增加。研究区植被生长与气象、土壤水分和地下水位埋深都有关系。气温与植被指数相关关系较好,相关系数为0.822,而降水对植被的生长也有一定的作用。植被指数与表观热惯量是正相关关系,相关系数为0.979。区内植被的地下水位埋深范围为0～12 m,在水位埋深约为6.5 m的地方,植被长势最好。 相似文献
10.
植被是流域水循环过程的重要环境因子之一,植被变化对径流的影响是当前研究的国际前沿和热点问题。以全球变绿最突出的黄淮海流域为研究对象,基于1982-2016年水文气象观测资料及归一化植被指数（NDVI）数据,利用Mann-Kendall等趋势检验方法检测NDVI的时空变化特征。基于Budyko-Fu公式构建黄淮海流域水热耦合模拟模型,分析模拟径流对Budyko-Fu模型参数ω的敏感性;基于参数ω与气候、植被等要素的统计关系,建立利用气候季节性指数和NDVI计算参数ω的经验公式,利用弹性系数法,识别参数ω对NDVI变化的响应,利用复合函数链式求导法则研究NDVI变化对黄淮海流域径流的影响。结果表明:1982-2016年黄淮海流域NDVI呈显著增加趋势;NDVI增加会使模型参数ω增加,进而导致径流量减少;NDVI每增加10%,黄淮海流域径流量平均减少8.3%;植被变化对径流的影响具有显著的空间差异性,气候越干旱、植被条件越差地区的NDVI变化对径流影响越显著。 相似文献
11.
Response of runoff to climate change in the area of runoff yield in upstream Shiyang River Basin,Northwest China: A case study of the Xiying River 
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下载免费PDF全文 The objective of this study was to analyze the response of runoff in the area of runoff yield of the upstream Shiyang River basin to climate change and to promote sustainable development of regional water resources and ecological environment. As the biggest tributary of the Shiyang River, Xiying River is the only hydrological station (Jiutiaoling) that has provincial natural river and can achieve long time series monitoring data in the basin. The data obtained from this station is representative of natural conditions because it has little human activites. This study built a regression model through identifying the characteristics of runoff and climate change by using Mann-Kendall nonparametric statistical test, cumulative anomaly, and correlation analysis. The results show that the average annual runoff is 320.6 million m3/a with the coefficient of variation of 0.18 and shows slightly decrease during 1956–2020. It has a significant positive correlation the average annual precipitation (P<0.01). Runoff is sensitive to climate change, and the climate has becoming warm and wet and annual runoff has entering wet period from 2003. Compared to the earlier period (1955–2000), the increases of average annual temperature, precipitation and runoff in recent two decades were 15%, 9.3%, and 7.8%, respectively. Runoff in the Shiyang River is affected by temperature and precipitation among climate factors, and the simulation results of the runoff-climate response model (R = 0.0052P ? 0.1589T + 2.373) indicate that higher temperature leads to a weakening of the ecological regulation of surface runoff in the flow-producing area. 相似文献
12.
长江源区不同植被覆盖下产流产沙效应初步研究 总被引：15，自引：2，他引：13
在长江源区北麓河支流左冒西孔曲流域建立了不同植被覆盖下的天然径流观测场,观测天然降水和人工模拟降水在相同坡度不同植被覆盖下降水的产流产沙效应.结果表明:在典型高寒草甸草地30°坡面上,相同降水条件下,30%覆盖度的场地的地表径流产出量明显大于覆盖度92%和68%两个场地,同时产沙量也显著高于两个高盖度场地的,平均单次降水形成的泥沙量是后两种情形的2~4倍,由此造成地表侵蚀量平均为后两种情形的3~10倍;但在相同降水条件下,92%高盖度场地产生的径流量比68%盖度场地产生的径流量大,产沙量刚好相反.不同降水形态对于下垫面产流产沙过程也具有明显影响,无论下垫面状况如何,在几种降水形态中,降雪融水的产流量最大,产沙量最小.人工模拟的结果表明,对于覆盖度<68%的中、强度退化草地,次降水量在3.5 mm时,就形成了较为明显的径流和产沙效应.当次降雨量达到7.2 mm,降雨持续时间30 min,覆盖度为30%、68%和92%的25 m2场地分别形成2885 mL、2450 mL和1030 mL的径流量;覆盖度<30%的退化草地泥沙含量明显高于高覆盖度的,相同降水形成的平均泥沙含明显高于高覆盖度的, 相同降水形成的平均泥沙含量高达2~7倍. 相似文献
13.
1975-2011年渭河上游径流演变规律及对气候驱动因子的响应 总被引：3，自引：1，他引：2
为探讨渭河上游径流的变化特征及其对气候变化的响应,选取1975-2011年河流实测径流量进行计算和分析. 结果表明：近40 a来,渭河上游径流总体呈明显下降趋势,其中,20世纪90年代前处于丰水期,90年代后进入枯水期,进入21世纪有明显增多趋势. 径流年际丰枯变化激烈,枯水年的发生概率高、持续性强,最长的连枯年份达8 a. 径流量集中在汛期,各年代的分配峰型有所不同,在70、80年代为7、9月双峰,之后变为单峰型分布. 流域内气候增暖明显,降水减少,蒸发加剧;90年代为明显的暖干型气候,21世纪初期气候向暖湿型转变的过程对径流的增加十分有利. 径流对气候变化有较强响应,但响应程度随时间变化而变化. 通过定量分析气候因子对径流变化的贡献值,发现由于气候增暖导致潜在蒸散量的加剧对径流变化的负贡献达60%以上,绝对值高于降水量的正贡献. 相似文献
14.
周智勇 《水文地质工程地质》2020,47(6):81-90
基于Google Earth Engine遥感云平台收集1987—2016年Landsat系列遥感卫星影像,采用像元二分模型对承德市围场满族蒙古族自治县植被覆盖度进行估算,结合气象数据和地形信息,分析近30年来研究区植被覆盖动态变化规律。结果表明:围场县1987—2016年的归一化植被指数（NDVI）值总体上呈上升趋势,全县NDVI平均值从0.63提高到了0.78,植被覆盖状况不断改善。研究区植被改善情况中,1987—2016年NDVI大于0.15的面积比例占到全县植被面积的49.28%,占比最大。1987—2016年NDVI小于等于-0.15的植被面积比例仅为0.82%。1987—2016年,各级植被覆盖度的转移矩阵体现出2016年的植被状况明显好于1987年,极高覆盖度植被转入面积高达7 991.84 km2。1987—2016年植被覆盖景观破碎程度不断降低,平均斑块面积指数从13.147 8扩大到31.703 4,植被覆盖类型趋于集中分布,连通性好。研究区总体气候变化趋势对植被生长具有不利影响,不同坡度和坡向的植被覆盖状况不同,人类活动和社会经济因素的影响为研究区植被改善情况发挥着重要作用。 相似文献
15.
为了解森林退化的原因,利用2000-2015年的MODIS NDVI数据,在分析贵州省植被变化趋势的基础上识别了归一化植被指数（NDVI)显著下降的区域,并在NDVI显著下降区选取面积大于10 km2的森林图斑为兴趣区,分析其内气候变化趋势及对森林NDVI值的影响。研究表明:197个兴趣区主要分布在贵州省西北部的赤水—习水、东北部的梵净山和东南部的非喀斯特区域;区内春、夏季NDVI变化趋势与年NDVI值变化趋势一致,下降速率达到-0.01·yr-1,冬季与其他季节变化趋势相反,呈不显著升高趋势;区内春季和夏季气温升高显著,降水和日照时间无明显变化,整体气候变化呈暖干趋势;夏季温度升高是NDVI降低的主要驱动因素。 相似文献
16.
Based on GIMMS NDVI data of Qilian Mountains region during 1982-2006, using the maximum synthesis, mean method, slope analysis and correlation analysis, the spatial and temporal changes of vegetation cover and its correlations with climatic factors were studied in Qilian Mountains. The results showed that: ①Vegetation NDVI of Qilian Mountains increases from west to east in general, showing the distribution pattern of much more vegetation in east regions than in west regions; ②Vegetation NDVI of Qilian Mountains has generally increased in the past twenty five years, but there are obvious spatial differences, especially vegetation NDVI of middle and east regions increase obviously; ③There have been obvious differences on spatial variation of seasonal NDVI in the past twenty five years in Qilian Mountains, and the increased area of vegetation NDVI is the largest in summer, followed by autumn, spring, but the most reduced area of vegetation NDVI is in winter. The regions of increased vegetation NDVI concentrate on southern mountain of Qinghai Province and in Buha River Basin, while the regions of reduced vegetation NDVI concentrate on Wushaoling, Lenglongling and Daban mountain in each season; ④The correlations between monthly average vegetation NDVI and temperature and precipitation are very significant, which indicates that temperature and precipitation are the main factors affecting the change of vegetation NDVI in Qilian Mountains, but intensive human activities are also important factors affecting the change of vegetation NDVI in some areas. 相似文献
17.
承德是京津冀地区重要的水源涵养区和防风固沙区,是京津冀生态环境支撑区的重要组成部分,其植被状况将直接影响着区域生态环境质量的改善。基于MOD13Q1时间序列NDVI资料,利用线性回归分析法、像元二分法、稳定性分析法等测度承德市全域2000—2018年植被覆盖时空演变特征,并分析气候、地形等因素对植被覆盖的影响。结果表明:（1）承德市全域植被状况年际变化总体发生了改善,植被生长季夏季的NDVI值最高,月度变化中7月份NDVI值最大,多年均值达到0.775 2。（2）植被年际变化趋势显著性存在空间差异,植被指数极显著增加区域面积最大,占比59.08%,而极显著减少和显著减少的区域面积较小,分别占全域的0.76%和0.58%,主要分布在承德市中部、南部等地区。（3）承德市各区县植被覆盖状况均以较高覆盖度为主,面积达到45 585.69 km2。在多年植被覆盖度稳定性格局中,西北部波动较大,其余大部分地区稳定性好,波动较低。（4）承德市NDVI受5—7月份降水量和月均温的影响较大,植被的长势可能受到了前期气象条件的滞后效应影响。地形特征对承德全域植被覆盖状况也有一定的影响,总体来看承德市地势低平地区的NDVI值相对较低。研究结果可为承德市加强重要区域生态保护、优化国土空间开发格局和科学制定生态修复措施提供参考。 相似文献
18.
基岩风化体现了构造与气候对地貌演化过程的共同作用。晚新生代的强烈构造抬升和干旱的气候条件,使得祁连山成为研究基岩风化与地貌演化过程的理想场所。借用施密特锤系统地研究了基岩回弹值（R）在黑河流域内不同海拔高度内的变化,结果显示流域平均的R值与侵蚀速率具有较好的相关性,意味着R值可以作为风化强度空间变化的代用指标。研究区内各种岩石类型的R值变化相差不大,说明岩性对R值的影响较小。进一步将R值与气候因子和区域地形进行比较发现：气温、降水与NDVI对R值的影响较强;坡度与局地高差对R值影响较弱,高程与R值在海拔小于3 800 m时呈现负相关关系,在大于3 800 m时呈现正相关关系。 相似文献
19.
人类活动引起的我国西北地区21世纪温度和降水变化情景分析 总被引：42，自引：7，他引：35
使用IPCCWG1第三次科学评估报告中给出的7个全球气候系统模式的模拟预测结果,分析了人类活动对中国西北地区气候变化的影响.模拟结果表明,由于温室气体增加(GG)或温室气体与硫化物气溶胶(GS)增加,21世纪西北地区气温将可能平均变暖42～60℃·100a-1.降水的变化较为复杂,由于温室气体的影响,未来西北地区降水将增加;考虑温室气体和硫化物气溶胶的共同影响,则略有增加.模式平均结果表明,未来西北地区降水将可能增加15～39mm·100a-1. 相似文献
20.
Hassan Khosravi Ali Azareh Hadi Eskandari Dameneh Elham Rafiei Sardoii Hamed Eskandari Dameneh 《Arabian Journal of Geosciences》2017,10(4):93
The present research evaluated the relation between the normalized difference vegetation index (NDVI) changes and the climate change during 2000–2014 in Qazvin Plain, Iran. Daily precipitation and mean temperature values during 2015–2040 and 2040–2065 were predicted using the statistical downscaling model (SDSM), and these values were compared with the values of the base period (2000–2014). The MODIS images (MOD13A2) were used for NDVI monitoring. In order to investigate the effects of climate changes on vegetation, the relationship between the NDVI and climatic parameters was assessed in monthly, seasonal, and annual time periods. According to the obtained results under the B2 scenario, the mean annual precipitation at Qazvin Station during 2015–2040 and 2040–2065 was 6.7 mm (9.3%) and 8.2 mm (11.36%) lower than the values in the base period, respectively. Moreover, the mean annual temperature in the mentioned periods was 0.7 and 0.92 °C higher than that in the base period, respectively. Analysis of the correlations between the NDVI and climatic parameters in different periods showed that there is a significant correlation between the seasonal temperature and NDVI (P < 0.01). Moreover, the NDVI will increase 0.009 and 0.011 during 2015–2040 and 2040–2065, respectively. 相似文献