利用GRACE数据分析中国区域地下水变化

利用GRACE和GLDAS数据计算了2003年1月-2012年12月我国长江中下游平原、西南地区、华北平原的地下水储量变化.长江中下游平原与西南地区地下水储量最低值在冬季、最高值在9月,华北平原地下水储量最低值在6月、最高值在12月,结合3个区域降水与农业耕作模式对地下水储量变化进行分析.西南地区地下水储量变化最显著的为云南省,可能与云南省的气温和喀斯特地貌有关.冬季华北平原冬小麦存在越冬期,灌溉需水量减少,地下水储量上升;春末处于冬小麦和夏玉米的轮作期,农业灌溉需水量增加地下水储量减少,达到一年中的最低值.     

GNSS用于杭嘉湖平原地面沉降机理的研究

为研究GNSS静态观测监测大面积区域平原沉降机理,在杭嘉湖平原地区建立了由25个基准点和15个监测点组成的基准监测网,并根据2008-2014连续6年的GNSS大地高与精密水准测量数据的对比分析,验证了GNSS静态观测方法的实际精度。结果表明:GNSS大地高变化可以替代精密水准测量获取水准测量点的沉降值,为研究大区域平面沉降监测提供了有力支撑。     

基于PS-InSAR的2003—009年北京平原区沉降控制因素分析

对融合PS与小基线InSAR技术提取的北京市583129个观测点2003-2009年28个时序的实际数据分析,结合北京市的第四系沉积物岩性与厚度分布情况,北京市地下水抽采地点与取水量等实际数据,分析了北京市平原地区2003-2009年的地面沉降的控制因素。得出了第四系沉积物岩性与厚度是控制地面沉降的地质内因,而人工抽采地下水是导致地面沉降的主要的人为外因。     

水田SAR后向散射强度及干涉相干特性研究

利用2007-2011年获取的ALOS PALSAR HH极化方式的FBS及FBD共21景数据, 结合实地1:500土地利用分类图, 对苏南无锡惠山试验区进行了水稻田后向散射强度的时间特性试验及干涉相干特性分析。试验结果表明:该区水稻田后向散射强度随生长周期的变化而变化, 且与各生长阶段的灌溉需水规律的变化一致, 需水量越大, 后向散射强度值越小。干涉相干特性试验表明:同期干涉相干系数略高于非同期干涉相干系数, 且在同期干涉试验中, 时间基线相同的情况下, 非水稻种植期的干涉相干系数达到最高, 其值明显高于水稻种植期的相干系数, 该试验结果对苏南地表沉降监测SAR影像干涉对的选取及地物变化检测具有重要的参考价值。     

安徽省近50余年降水量时空变化特征分析

利用安徽省内15个和周边17个气象台站1957-2008年的降水资料,运用线性倾向估计和ArcGIS软件的空间分析等方法,分析从1957-2008年安徽省降水量的时空分布规律和长期变化趋势,并选取900mm,1200mm,1500mm为特定等值线,通过对特定等值线的变化来分析不同年代降水量的空间差异.研究结果表明：安徽省近50余年来降水整体上呈上升趋势,省内各区域降水差异较大,呈南多北少,山区多平原少的特点;从各区域降水的变化趋势来看,南方山区逐步减少,而北方平原呈逐步增加的趋势,南北降水差距在不断缩小.     

巨石阵：古代王室的神秘墓地？

英国南部索尔兹伯里平原上的巨石阵是世界上最著名的史前建筑遗迹,建造于公元前3000年到公元前1600年,每年都有100万人从全球各地慕名前来参观这一世界级的文化遗产。巨石阵的建造起因和方法在考古界一直是个不解之谜,学者们猜测其可能是用于宗教祭祀的寺庙或是计算天文历法的工具。     

两湖平原地下水微动态影响因素相关性分析

针对地下水微动态影响因素的相关模型建立的研究较缺乏这一问题,该文以两湖平原地区的3个地下水监测站数据为基础,结合该地区气象站点2009—2013年的气压、降水量数据,采用反距离权重插值法内插地下水站点的气压与降水量数据,分别建立地下水与气压等效水高、降水量的皮尔逊相关模型,计算了地下水与气压等效水高、降水量的相关系数,分析该地区地下水的动态变化及其与气压、降水量的相关性。分析结果表明,两湖平原地区地下水对气压的响应呈负相关性,不同区域的相关性不同;降水量对地下水位的影响比较复杂,直接影响并不明显。     

不同大地水准面精化方法的试算与分析

介绍了陆地局部大地水准面精化的四种方法，并首次采用四种方法在平原和山区的四个不同试验区进行计算比较，分析GPS／水准、地形和不同精化方法对精化结果的影响．对我国不同地形的大地水准面精化工作提出建设性的建议。     

星载微波SSM/Ⅰ遥感在中国东北华北农田的辐射特征分析

本文研究了星载微波ＳＳＭ／Ⅰ１９９６年在中国东北华北平原农田上７个通道辐射亮度温度（ＴＢ）的遥感数据,提出用几个通道ＴＢ组合的散射指数和极化指数来分析中国平原地区农田的微波辐射特征,及其随生长季节的时间性变化。星载ＳＳＭ／Ⅰ数据可以监视农作物的生长和平原地区地面湿度的变化。本文还给出了大气和农作物地表矢量辐射传输的数值模拟结果。     

江苏沿海地区耕地分布格局及其变化特征

利用1990年、2000年和2010年的遥感解译土地利用数据提取耕地数据,运用耕地集中度指数、核密度计算等方法分析江苏沿海地区耕地资源空间分布格局及其变化特征.结果表明:①1990-2010年,江苏沿海地区耕地面积所占比重较高,但呈逐年降低趋势,耕地数量逐年减少.耕地类型以平原水田、平原旱地两类为主,呈整体交错分布、部分集聚的分布格局;②从耕地分布状况来看,呈中部、南部高,北部略低的分布特征,耕地分布较集中,且在时间序列上有进一步加强的趋势,耕地区域变化差异性不明显;③从耕地核密度分布状况来看,密度高值区呈现扩散趋势,密度低值区呈集聚趋势,且在进一步增强.耕地整体呈中西部、西南部耕地分布稀疏,中东部、北部分布密集的空间分布特征.     

Agricultural Area Diversification and Crop Water Demand Analysis: A Remote Sensing and GIS Approach

Large scale adoption of input intensive rice–wheat cropping system in the centrally located Jalandhar district of Indian Punjab has led to over-exploitation of ground water resources, intensive use of chemical fertilizers and deterioration of soil health. To overcome these shortfalls, in the present study, agricultural area diversification plan has been generated from agricultural area and crop rotation maps derived from remote sensing data (IRS P6-AWiFS and RADARSAT ScanSAR) along with few agro-physical parameters in GIS environment. Cropping system indices (area diversity, multiple cropping and cultivated land utilization) were also worked out from remote sensing data .Analysis of remote sensing data (2004–05) revealed that rice and wheat individually remained the dominant crops, occupy 57.8% and 64.9% of total agricultural area (TAA), respectively. Therefore, in the diversified plan, it is suggested that at least 39% of the current 40% TAA under rice–wheat rotation should be replaced by other low water requiring, high value and soil enriching crops, particularly in coarse textured alluvial plain having good quality ground water zones with low annual rainfall(<700 mm). This will reduce water requirement to the tune of 15,660 cm depth while stabilizing the production and profitability by crop area diversification without further degradation of natural resources.     

Evaluation of irrigation management in a Canal Command area based on Agrometeorology and Remote Sensing

Efficacy of irrigation management of wheat and mustard crops grown in Western Yamuna Canal Command area was determined in the present study from agro-climatic data merged with Maximum Likelihood Classified (MXL) satellite image and from irrigation scheduling efficiencies obtained through FAO model CROPWAT. For computing irrigation scheduling efficiencies, amount of water supplied at different growth stages, soil water depletion and crop water need have been taken into account. Agro-meteorological data in combination with MXL classified crop map approximated the deficiency of applied irrigation amount compared to requirement. Irrigations at 35-80 Days After Sowing (DAS) for two times of applications, 30-60-90 DAS for three, 21-50-80-110 DAS in case of four and 20-45-70-90-120 DAS in case of five irrigations have yielded better scheduling efficiencies for wheat than other times of applications in all soil associations.     

Studies on irrigation distribution equity and crop growth performance in a Canal Command using remote sensing

Irrigation distribution equity and crop growth were studied in Delhi Sub-branch of Western Yamuna Canal Command. Total irrigation was estimated from the canal and tube well discharge data and irrigation distribution equity was expressed in terms of Theil’s and Christiansen’s Coefficients for nearly 140 wheat fields randomly chosen over the command. Crop growth performance for these plots was assessed from the Normalized Difference Vegetation Index (NDVI) obtained from the IRS, LISS II data. Four soil associations viz., Nabha-Ghoga, Daryapur-Hissar, Holambi-Nabha and Khampur-Hissar mainly represented the study area. In general, increase in amount of irrigation enhanced the growth performance of the wheat crop. Increase in distribution equity within soil associations slightly improved the growth performance of the crop. Over and above, the irrigation equity, quality and quantity constraints to irrigation, the other soil parameters like CEC, applied P also contributed to differences in wheat growth as observed from the stepwise multiple regression analysis. Irrigation performance indices were estimated from water distribution between soil associations and from water requirement of crop, indicated performance slightly below the critical level.     

Effects of water and heat on growth of winter wheat in the North China Plain

The North China Plain (NCP) was selected as the study area and the effects of water and heat were analysed to determine the dominant factor affecting winter wheat growth. The mean, minimum and maximum temperatures, precipitation and soil moisture data were selected to analyse the correlations between the leaf area index (the growth indicator) and these factors using long time series half-monthly data (2–5 months) (from 1982 to 2010). The results showed that temperature was the main factor affecting the growth of winter wheat in the NCP. The growth of winter wheat had weak correlations with precipitation and soil moisture and the influence of water on winter wheat growth was smaller than the influence of heat. In the northern part of the NCP, mainly including the north-west region of Shandong Province and the southern region of Hebei Province, irrigation was necessary in late February and early March.     

Study of irrigation and crop water requirements and growth of two <Emphasis Type="Italic">Rabi</Emphasis> crops grown in a semi arid region using agrometeorology and remote sensing

Irrigation water requirements of wheat and mustard crops grown in Western Yamuna Canal Command area were estimated using FAO model CROPWAT with the help of agrometeorological and remote sensing data (1986–1998 and 2008). The variations in irrigation water requirements of these two crops were judged by calculating coefficient of Variations (CVs) of yearly data. Crop coefficient values were obtained through FAO (1993) method. Supervised Maximum Likelihood Classification (MXL) of IRS 1B image was done to estimate area under wheat and mustard in the canal command. Water need was calculated from amount of supply and water requirement for the whole area. Results showed that ET_crop values of both wheat and mustard varied very little over different years (CVs 4.7% and 5.6% respectively). Irrigation water requirements of both these crops were having relatively large variations (CVs 14.1% and 22.6% respectively) which were mainly because of high variations of their effective rainfall (CVs 61.1% and 69.2% respectively). In general, increase in amount of irrigation enhanced the growth performance of the wheat crop. Increase in distribution equity within soil associations slightly improved the growth performance of the wheat crop. Agro-climatic data merged with satellite image approximated the deficiency of applied irrigation amount (549.5 ha-m for wheat and 692.7 ha-m for mustard) as compared to requirement.     

An object-based image analysis approach to assess irrigation-water consumption from MODIS products in Ethiopia

Efficient water-resource management is essential with regard to food security, growing populations and climate change. This is especially important for low- and middle-income (LMC) countries where food is often locally produced by traditional smallholder farming. Detailed knowledge of the spatio-temporal distribution of irrigation-water consumption provides valuable information to anticipate local food shortages and water scarcity as a result of climate variability. Yet, adequate techniques to quantify irrigation-water consumption at field level over large areas are lacking. Irrigation estimates generally have a coarse resolution making them inadequate for field-level assessments.This study developed a remote-sensing-based approach to quantify spatio-temporal patterns of irrigation-water consumption at field level using the MODIS evapotranspiration product (MOD16A2) and existing land-use maps on the spatio-temporal distribution of irrigated agriculture. Object-based image analysis was used to establish local evapotranspiration differences between irrigated and rainfed fields on a monthly basis, which are the irrigation-water consumption rates of the irrigated fields. This novel method was applied to a study area in the Central Rift Valley in Ethiopia where smallholder farming is dominant and only a few large-scale farms are present. Comparison with irrigation-water-consumption values of a local irrigation scheme showed that the monthly temporal dynamics were captured quite well, but lower values were calculated compared to the scheme's field data. Comparison with two validated remote-sensing based studies in Africa showed good agreement as irrigation-water-consumption estimates were in the same order of magnitude. Irrigation-water consumption follows the temporal rainfall pattern, i.e. irrigation practices intensify with increased water availability. Surface water is commonly used for irrigation in the study area.Our study shows that smallholder practices have a lower irrigation-water consumption compared to modern large-scale farms by approximately a factor 3. Irrigation-water consumption in the area is considerable, especially during the dry season. On average 32 % of excess water (precipitation – evapotranspiration) is consumed for irrigation. For smallholder irrigation and large-scale irrigation specifically this is 28 % and 63 % respectively.The object-based approach presented here is an operational mapping method for field-level irrigation-water-consumption over large areas. MOD16A2 is a global open-source readily-available evapotranspiration product used here although an evapotranspiration product with a higher spatial resolution might be preferred. Our approach can provide irrigation-water-consumption estimates over large areas in data-poor regions, which will increase the understanding of spatio-temporal patterns of smallholder irrigation and provide information to optimize water use.     

冬小麦旱情遥感监测模型研究

本研究依据土壤水量平衡及能量平衡的原理,提出了一套利用遥感方法监测冬小麦干旱及建模的方法。首先,用热惯性方法建立试区土壤表观热惯量与土壤水分的关系,用其估算初始土壤含水量(W_0);再用NOAA-AVHRR数字图像和气象数据相结合的方法估算冬小麦地的蒸散(E_t);从而根据水量平衡方程获得某一时段(旬)的土壤含水量(W_t);最后,根据冬小麦的需水规律和土壤有效水含量构造干旱指数模型。试验表明,此模型反映了作物干旱的本质,能大范围有效地监测作物旱情。     

中国湿地变化的驱动力分析

在全球气候变化及中国社会经济迅速发展的背景下,为了解中国湿地分布的时空动态特征及演化规律,以4期(1978年、1990年、2000年、2008年)中国湿地遥感制图数据和3期(1990年、2000年、2005年)土地利用数据为基础,同时考虑到对湿地变化的影响程度和数据的可获取性,选取12个影响因子(平均温度、平均湿度、累计降水量、人口数量、地区生产总值、农林牧渔产值、耕地面积、粮食产量、有效灌溉面积、水库库容量、除涝面积、治碱面积)研究1978年—2008年这30年间中国湿地变化的驱动机制。考虑到地理现象的空间非平稳性,本文采用地理加权回归的方法分析驱动因子对湿地变化的影响作用。地理加权回归作为一种局部线性回归方法,能够直观地反映湿地驱动因子对湿地作用的地域差异。结果表明:不同类型的湿地变化的主要影响因素不同,内陆湿地与温度、降水以及农业耕作灌溉等密切相关;人工湿地与经济发展水平和水利设施兴建密切相关;滨海湿地与农林牧渔产业和人口等密切相关。同一类型湿地变化的主要影响因素随着时间推移也有所变化,并且影响程度在地域上也存在较为明显的南北和东西差异。本次研究结果基本反映了1978年—2008年中国湿地变化的特征规律。     

InSAR视角下准噶尔盆地农业灌溉区地表形变特征和演化规律

抽取地下水进行农业灌溉是导致地下水位快速下降的重要因素，而长期过度开采地下水往往会引发地面沉降灾害，这种现象在干旱和半干旱地区非常普遍。为了研究农业灌溉超采引发的地表形变特征和演化规律，本文以准噶尔盆地南缘、天山北麓地带为研究区域，利用SBAS-InSAR技术对2003年—2009年覆盖呼图壁县的ENVISAT/ASAR升、降轨数据进行处理，获取了该地区的地表形变场，并结合研究区的农业灌溉方式、水资源补给和季节变化等资料对地面沉降的时空变化特征进行分析，为水资源和农业可持续发展提供参考意义。实验表明，研究区内主要有两个沉降幅度较大的漏斗，且都位于农田区域。2007年以前，研究区地表没有显著形变，之后发生了较大量级的沉降。采用传统灌溉方式和时针式灌溉系统的农业区平均沉降速率最高分别可达50 mm/a和30 mm/a，前者在时间上呈线性变化，而后者具有显著的周期性变化特征。在冬季时，采用时针式灌溉系统的地区地面抬升量可达40 mm，远大于传统灌溉方式的农田区域，而夏季地面沉降速率可达200 mm/a。对研究区农业灌溉活动进行分析后发现，农业灌溉造成的地下水超采是该地区地面沉降的主要影响因素，其形变机制与季节变化具有较高的相关性，在灌溉活动休止期内地表形变取决于地下水的补给量。研究区内的形变特征和影响因素分析将为地下水资源的充分利用和农业的可持续发展提供有效的信息。     

Crop Evapotranspiration Estimation for Wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.) Using Remote Sensing Data in Semi-Arid Region of Maharashtra

Penman–Monteith method adapted to satellite data was used for the estimation of wheat crop evapotranspiration during the entire growth period using satellite data together with ground meteorological measurements. The IRS-1D/IRS-P6 LISS-III sensor data at 23.5 m spatial resolution for path 096 and row 059 covering the study area were used to derive, albedo, normalized difference vegetation index, leaf area index and crop height and then to estimate wheat crop evapotranspiration referred to as actual evapotranspiration (ETact). The ETact varied from 0.86 to 3.41 mm/day during the crop growth period. These values are on an average 16.40 % lower than wheat crop potential evapotranspiration (ETc) estimated as product of reference crop evapotranspiration estimated by Penman–Monteith method and lysimetric crop coefficient (Kc). The deviation of ETact from ETc is significant, when both the values were compared with t test for paired two sample means. Though the observations on ETact were taken from well maintained unstressed experimental plot of 120 × 120 m size, there was significant deviation. This deviation could be attributed to, the satellite images representing the actual crop evapotranspiration as function crop canopy biophysical parameters, condition of the crop stand, climatic and soil conditions and the microclimate variation over area of one hectare. However, Penman–Monteith method represents a flat rate of specific growth stage of the crop.