基于MOD16数据,计算作物缺水指数(Crop Water Stress Index,CWSI),结合汾河流域气象站点数据、植被指数数据和土地利用数据,采用差值法、线性趋势法和相关分析法,分析汾河流域2000—2021年干旱时空变化特征。结果表明:(1)CWSI能有效监...基于MOD16数据,计算作物缺水指数(Crop Water Stress Index,CWSI),结合汾河流域气象站点数据、植被指数数据和土地利用数据,采用差值法、线性趋势法和相关分析法,分析汾河流域2000—2021年干旱时空变化特征。结果表明:(1)CWSI能有效监测汾河流域旱情,其与10 cm土壤相对湿度呈显著负相关。(2)汾河流域CWSI空间分布差异明显,呈现出南湿北旱的特点。(3)汾河流域CWSI年际变化较为平稳,而月变化波动较大,5月CWSI达到年内峰值。(4)汾河流域不同生长期内干旱情况差异显著,生长季前期(4—5月)特旱区占汾河流域总面积的48.55%;生长季中期(6—8月)基本全域无旱;生长季后期(9—10月),仅11.17%的地区发生干旱。(5)不同土地利用类型干旱程度不同,CWSI从小到大依次为:林地(0.686)<草地(0.749)<耕地(0.751)<未利用地(0.758)<城镇(0.765)。本研究结果可为汾河流域旱情监测和抗旱决策的制定提供科学数据支撑。展开更多
为了促进贵州省农业和生态环境可持续发展,基于作物缺水指数(Crop Water Stress Index,CWSI),结合气象、植被指数等数据,采用Theil-Sen Median趋势分析、Mann-Kendall检验、变异系数和相关性分析等方法,对贵州省2000—2019年的干旱时空...为了促进贵州省农业和生态环境可持续发展,基于作物缺水指数(Crop Water Stress Index,CWSI),结合气象、植被指数等数据,采用Theil-Sen Median趋势分析、Mann-Kendall检验、变异系数和相关性分析等方法,对贵州省2000—2019年的干旱时空变化特征、趋势及影响因素进行了分析。研究表明:(1)贵州省CWSI多年均值为0.43,整体处于轻旱等级,空间分布为东南湿润,西北干旱,多年旱情变化呈缓解趋势;(2)从地貌类型来看,非喀斯特地貌CWSI多年均值为0.37,整体处于无旱等级,喀斯特地貌均值为0.47,处于轻旱状态;(3)从植被类型来看,除针叶林整体处于无旱状态外,其他植被类型都处于轻旱等级,且针叶林的变异系数(CV)值较其他林地高,说明其对气候因子的敏感性高,抗旱能力强;(4)贵州省CWSI与降水和气温均呈负相关,负相关面积占比为95%和54%,说明降水对CWSI的影响较大。综合分析得出,贵州省东南部湿润,西北地区干旱,全省干旱受喀斯特地貌、降水的影响较大。展开更多
Temperature vegetation dryness index (TVDI) and crop water stress index (CWSI) are two commonly used remote sens- ing-based agricultural drought indicators. This study explored the applicability of monthly moderat...Temperature vegetation dryness index (TVDI) and crop water stress index (CWSI) are two commonly used remote sens- ing-based agricultural drought indicators. This study explored the applicability of monthly moderate resolution imaging spectroradiometer (MODIS) normalized difference vegetation index (NDVI) and land surface temperature (LST) data for agricultural drought monitoring in the Guanzhong Plain, China in 2003. The data were processed using TVDI, calculated by parameterizing the relationship between the MODIS NDVI and LST data. We compared the effectiveness of TVDI against CWSI, derived from the MOD16 products, for drought monitoring. In addition, the surface soil moisture and monthly pre- cipitation were collected and used for verification of the results. Results from the study showed that: (1) drought conditions measured by TVDI and CWSI had a number of similarities, which indicated that both CWSI and TVDI can be used for drought monitoring, although they had some discrepancies in the spatiotemporal characteristics of drought intensity of this region; and (2) both standardized precipitation index (SPI) and SM contents at the depth of 10 and 20 cm had better correlations to CWSI than to TVDI, indicating that there were more statistically significant relationships between CWSI and SPI/SM, and that CWSI is a more reliable indicator for assessing and monitoring droughts in this region.展开更多
为了准确提取作物冠层温度,监测作物水分亏缺状态,以不同水分处理的生菜为研究对象,分别利用手持式热像仪和佳能相机获取生菜的热红外和可见光图像,计算生菜冠层可见光图像与热红外图像的仿射变换参数,并进行配准融合,以获取生菜冠层区...为了准确提取作物冠层温度,监测作物水分亏缺状态,以不同水分处理的生菜为研究对象,分别利用手持式热像仪和佳能相机获取生菜的热红外和可见光图像,计算生菜冠层可见光图像与热红外图像的仿射变换参数,并进行配准融合,以获取生菜冠层区域的热红外图像,而后计算不同处理下的基于冠层温度的水分胁迫指数(Crop Water Stress Index, CWSI)与日蒸散量(Evapotranspiration,ET),分析不同灌溉处理下CWSI同ET的相关关系来监测生菜水分亏缺程度。结果表明,基于仿射变换的热红外目标提取方法可以实现生菜冠层的准确提取,剔除背景后生菜冠层的平均温度值由20.25℃下降至19.25℃。不同水分处理下的生菜热红外冠层的CWSI值展示出明显的差异,且CWSI与ET呈显著负相关,当CWSI越大,ET越小,表明CWSI可以应用在生菜水分胁迫状态监测,能够很好的反应土壤水分含量变化状况。展开更多
为了给以作物高效灌溉制度提供理论依据,对不同供水条件下冬小麦冠层温度进行了多年田间观测,模拟了以土壤水分条件为主导的冠气温差、叶水势、水分亏缺指数等的变化规律及其对影响因素的响应。结果表明,冬小麦各生育阶段不同供水处理...为了给以作物高效灌溉制度提供理论依据,对不同供水条件下冬小麦冠层温度进行了多年田间观测,模拟了以土壤水分条件为主导的冠气温差、叶水势、水分亏缺指数等的变化规律及其对影响因素的响应。结果表明,冬小麦各生育阶段不同供水处理冠层温度(T c)受土壤水分影响明显,处理间冠气温差(ΔT)差异极显著。叶水势(LW P)与ΔT、作物水分胁迫指数(CW S I)相关显著。LW P=-1.8M Pa,CW S I=0.40是指示冬小麦发生水分胁迫的关键性指标。综合各指标,为了达到节水目的,使ΔT维持在0^-4℃,可获得冬小麦产量最优值,此时冬小麦灌溉量下限应使土壤相对含水量达到58.7%。展开更多
文摘基于MOD16数据,计算作物缺水指数(Crop Water Stress Index,CWSI),结合汾河流域气象站点数据、植被指数数据和土地利用数据,采用差值法、线性趋势法和相关分析法,分析汾河流域2000—2021年干旱时空变化特征。结果表明:(1)CWSI能有效监测汾河流域旱情,其与10 cm土壤相对湿度呈显著负相关。(2)汾河流域CWSI空间分布差异明显,呈现出南湿北旱的特点。(3)汾河流域CWSI年际变化较为平稳,而月变化波动较大,5月CWSI达到年内峰值。(4)汾河流域不同生长期内干旱情况差异显著,生长季前期(4—5月)特旱区占汾河流域总面积的48.55%;生长季中期(6—8月)基本全域无旱;生长季后期(9—10月),仅11.17%的地区发生干旱。(5)不同土地利用类型干旱程度不同,CWSI从小到大依次为:林地(0.686)<草地(0.749)<耕地(0.751)<未利用地(0.758)<城镇(0.765)。本研究结果可为汾河流域旱情监测和抗旱决策的制定提供科学数据支撑。
文摘为了促进贵州省农业和生态环境可持续发展,基于作物缺水指数(Crop Water Stress Index,CWSI),结合气象、植被指数等数据,采用Theil-Sen Median趋势分析、Mann-Kendall检验、变异系数和相关性分析等方法,对贵州省2000—2019年的干旱时空变化特征、趋势及影响因素进行了分析。研究表明:(1)贵州省CWSI多年均值为0.43,整体处于轻旱等级,空间分布为东南湿润,西北干旱,多年旱情变化呈缓解趋势;(2)从地貌类型来看,非喀斯特地貌CWSI多年均值为0.37,整体处于无旱等级,喀斯特地貌均值为0.47,处于轻旱状态;(3)从植被类型来看,除针叶林整体处于无旱状态外,其他植被类型都处于轻旱等级,且针叶林的变异系数(CV)值较其他林地高,说明其对气候因子的敏感性高,抗旱能力强;(4)贵州省CWSI与降水和气温均呈负相关,负相关面积占比为95%和54%,说明降水对CWSI的影响较大。综合分析得出,贵州省东南部湿润,西北地区干旱,全省干旱受喀斯特地貌、降水的影响较大。
基金support of the National Natural Science Foundation of China (41171310)
文摘Temperature vegetation dryness index (TVDI) and crop water stress index (CWSI) are two commonly used remote sens- ing-based agricultural drought indicators. This study explored the applicability of monthly moderate resolution imaging spectroradiometer (MODIS) normalized difference vegetation index (NDVI) and land surface temperature (LST) data for agricultural drought monitoring in the Guanzhong Plain, China in 2003. The data were processed using TVDI, calculated by parameterizing the relationship between the MODIS NDVI and LST data. We compared the effectiveness of TVDI against CWSI, derived from the MOD16 products, for drought monitoring. In addition, the surface soil moisture and monthly pre- cipitation were collected and used for verification of the results. Results from the study showed that: (1) drought conditions measured by TVDI and CWSI had a number of similarities, which indicated that both CWSI and TVDI can be used for drought monitoring, although they had some discrepancies in the spatiotemporal characteristics of drought intensity of this region; and (2) both standardized precipitation index (SPI) and SM contents at the depth of 10 and 20 cm had better correlations to CWSI than to TVDI, indicating that there were more statistically significant relationships between CWSI and SPI/SM, and that CWSI is a more reliable indicator for assessing and monitoring droughts in this region.
文摘为了准确提取作物冠层温度,监测作物水分亏缺状态,以不同水分处理的生菜为研究对象,分别利用手持式热像仪和佳能相机获取生菜的热红外和可见光图像,计算生菜冠层可见光图像与热红外图像的仿射变换参数,并进行配准融合,以获取生菜冠层区域的热红外图像,而后计算不同处理下的基于冠层温度的水分胁迫指数(Crop Water Stress Index, CWSI)与日蒸散量(Evapotranspiration,ET),分析不同灌溉处理下CWSI同ET的相关关系来监测生菜水分亏缺程度。结果表明,基于仿射变换的热红外目标提取方法可以实现生菜冠层的准确提取,剔除背景后生菜冠层的平均温度值由20.25℃下降至19.25℃。不同水分处理下的生菜热红外冠层的CWSI值展示出明显的差异,且CWSI与ET呈显著负相关,当CWSI越大,ET越小,表明CWSI可以应用在生菜水分胁迫状态监测,能够很好的反应土壤水分含量变化状况。
文摘为了给以作物高效灌溉制度提供理论依据,对不同供水条件下冬小麦冠层温度进行了多年田间观测,模拟了以土壤水分条件为主导的冠气温差、叶水势、水分亏缺指数等的变化规律及其对影响因素的响应。结果表明,冬小麦各生育阶段不同供水处理冠层温度(T c)受土壤水分影响明显,处理间冠气温差(ΔT)差异极显著。叶水势(LW P)与ΔT、作物水分胁迫指数(CW S I)相关显著。LW P=-1.8M Pa,CW S I=0.40是指示冬小麦发生水分胁迫的关键性指标。综合各指标,为了达到节水目的,使ΔT维持在0^-4℃,可获得冬小麦产量最优值,此时冬小麦灌溉量下限应使土壤相对含水量达到58.7%。