基于多源遥感数据的东居延海水面面积监测对比研究Word下载.docx

1、遥感技术在生态调水监测研究中，已逐步被应用，并取得显著效果。乔西现1采用ETM影像解译获取了黑河下游的土地利用数据，研究了黑河尾闾东、西居延海调水后水资源、植被及生态环境的恢复情况。郭铌2运用MODIS影像数据对黑河调水的下游生态环境恢复效果进行监测分析。中国水科院遥感技术应用中心利用MODIS影像数据监测了黑河流域2002年第一次调水结束后东居延海进水情况。MODIS影像数据获取重复周期短，获取方便，是进行长期连续监测的重要数据。但是由于其分辨率低，解译精度较低，给生产应用带来一定困难。高分辨率遥感影像能够很好地描述地物的细节信息，可以准确地获取水面面积，获取较高的解译精度。因此，高分辨率遥

2、感数据获得的水面面积可视为一种准确的观测数据，可用来检验低分辨率的MODIS影像解译结果，分析其误差，对采用MODIS数据进行东居延海水面面积监测具有重要意义。本文以东居延海为例，分别采用多源高分辨率遥感影像和MODIS影像提取水面面积，并将高分辨率遥感数据提取结果分别与观测数据和MODIS数据解译结果进行对比，评价精度和分析误差，进一步探讨东居延海水面面积遥感监测方法。图1 技术路线图2研究数据及研究区概况东居延海位于内蒙古自治区阿拉善盟额济纳旗北部，19281932年，中瑞西北考察队考察时，东居延海水域面积为35 km2。到1958年（丰水年），东居延海水域面积仍有35.5 km2。由于上

3、游来水减少，东居延海解放后干涸6次，到1992年彻底干涸，生态环境加剧恶化。随着1999年黑河采取水量统一调度，黑河水重新注入东居延海，形成水面，周边地区的生态环境得到恢复。本次研究采用TM、中巴资源二号卫星（CBERS 2）等多光谱数据以及P5全色片数据等10期高分辨率遥感影像，见表1 ，并收集高分辨遥感数据获取日期的MODIS 1B数据。此外，还收集东居延海的水面面积旬观测数据及调水期间的日观测数据。表1 研究数据统计表序号影像获取日期影像类型影像分辨率（m）12007.6.19TM3022007.7.532007.10.7P52.542008.5.1152008.7.1462008.8.

4、2472008.8.26CBERS 219.582008.9.992008.10.2102008.10.113数据预处理本文采用MODIS Reprojection Tool Swath工具对MODIS 1B数据进行辐射校正、投影变换、几何校正、“双眼皮”现象去除等处理，使MODIS数据能够满足东居延海水面面积提取要求。利用多源、多时相高分辨率遥感影像进行东居延海水面面积监测，需要对高分辨率遥感影像进行几何配准。几何配准以2008年10月11日的TM影像为基准，将其他时间及其他传感器获取的高分辨率遥感影像统一校正到这期影像。几何配准采用二次多项式，重采样方法采用双线性插值法。4结果及分析4.1

5、结果对经过几何校正等预处理的MODIS影像和高分辨率遥感影像在ENVI遥感处理软件中进行目视解译，提取得到东居延海水面面积，解译结果如表2。以高分辨率遥感影像水面面积解译结果为基准，计算得到MODIS数据及观测资料的误差，见表2。表2 遥感影像解译水面面积结果对比影像获取日期高分数据解译面积（km2）MODIS影像解译结果水文观测结果面积（km2）误差（%）37.934.7-8.432.5-14.235.232.2-8.530.9-12.247.845.3-5.238.7-19.048.749.9+2.536.8-24.438.333.2-13.334-4.339.739.1-1.535.8-

6、9.838.238.0-0.535.7-6.538.53635.4-8.043.341.8-3.537.2-14.146.644.3-4.938-18.44.2MODIS影像与高分辨遥感影像解译结果比较由表2及图2可见，MODIS影像解译结果与高分辨遥感影像相比，误差最大为13.3%，最小0.5%。总体上看，误差不大，除2008年5月11日，MODIS影像的解译误差都控制在9%以内。MODIS影像解译结果整体上比TM影像解译结果要小，这是因为MODIS的空间分辨率最高为250m，影像上存在大量混合像元，东居延海的许多细节信息都被概化，如湖面较小的弯曲及湖内一些渚（small piece of

7、land in water）在MODIS影像上无法表征出来，而在高分辨率遥感影像上可以较为详细地表征（如图3）。2008年5月11日的MODIS影像解译误差较大，主要是因为该时期水面面积较小，湖内平均水位较低，而湖内水藻生长茂盛，且2008年的植被生长状况较2007年进一步提高，在MODIS影像上无法很好区分水体边界，导致MODIS影像解译误差明显增大（如图3）。图2 水面面积对比分析4.3 观测数据与高分辨遥感影像解译结果比较由表2及图2可见，水文观测值与高分辨率遥感解译结果的变化范围较大，误差最小值为4.3%，最大值为24.4%。由分析可知，造成两种方法监测结果差异一方面由于东居延海环境恶

8、劣，给实地人工观测带来困难，一定程度上会影响观测精度；另一方面，自从黑河实施统一水量生态调度以来，东居延海地区生态环境得到恢复，湖边及湖内植被生长越来越茂盛，对遥感影像识别水面边界带来影响。进一步分析可知，当观测水面面积在34-36平方公里时，水文观测值与高分辨率遥感影像的解译结果相差较小，观测值误差在10%以内；当观测水面面积值大于36平方公里及小于34平方公里时，观测误差在12%以上，甚至达到24.4%。造成这一现象的原因可能为，当水位较低时，湖内的渚逐渐露出水面积，同时湖内植被在遥感影像上的表征进一步明显；当水位较高时，水面面积淹没范围加大，湖面四周的植被被更多的淹没，植被覆盖的水体边界

9、区域进一步加大。这不但对野外水文观测造成影响，同时给遥感影像解译水面面积带来难度。 （a）TM原始影像 （b）MODIS原始影像（a）TM解译结果 （b）MODIS解译结果图3 2008年7月14日遥感影像及解译结果5讨论本文采用MODIS影像和高分辨率遥感影像对东居延海进行了水面面积提取，进一步分析比较了MODIS影像解译结果及水文观测值与高分辨率遥感影像解译结果的误差。得出以下结论：MODIS影像与高分辨率遥感影像的解译结果基本小于9%，由空间分辨率造成混合像元，概化了水面细节信息，是造成误差的主要原因；水文观测值与高分辨率遥感影像的解译结果相差较大，误差最大接近25%，初步分析观测环境恶

10、劣及生态环境复杂是造成两者差异的主要素。因此，为了更好地利用遥感影像进行东居延海水面面积监测，需要更深入到东居延海进行实地勘察，掌握高分辨遥感影像解译结果与水文观测值之间差异的根本原因，为利用多源遥感监测东居延海水面面积提供依据。参考文献1 乔西现，蒋晓辉，陈江南，等.黑河调水对下游东、西居延海生态环境的影响.西北农林科技大学学报（自然科学版），2007，35（6）：190-194.2 郭铌，梁芸，王小平.黑河调水对下游生态环境恢复效果的卫星遥感监测分析.中国沙漠，2004，10（6）：740-744.3 汤安国，张友顺，刘咏梅等.遥感数字图像处理.北京：科学出版社，2004.Comparis

11、on of Measured Area of East Juyanhai Using Multi-source Remote Sensing DataChen liang, Han Lin, He Houjun ,Zhang Xiangjuan（Information Center, Yellow River Conservancy Commission, Zhengzhou 45004, Henan, China）Abstract: MODIS image is an important data to monitoring the change of water surface area

12、of Juyanhai Lake. Understanding water surface area accurately is very important water regulation in Hei River. In this paper, water surface interpretation error with MODIS data was analyzed and verified by high resolution image, and also the water surface area interpreted by high resolution image wa

13、s compared with the hydrology observed data. The results state that interpretation error based on MODIS was controlled within 9%, which mainly for the detail generation caused by resolution; the error between the interpretation result basis on high resolution image and the hydrology observed value m

14、ainly caused by the complex ecological environment and the hard surveying environment. Key words: Multi-source remote sensing, High resolution, East Juyanhai Lake, Error analysis1 IntroductionHei River is the second largest inland river in china, flowing through the three provinces of Qinghai, Gansu

15、 and inner Mongolia, finally injecting East and West Juyanhai Lake, with total 821km length and 0.134 million km2. Hei River locates in the hinterland of northwest inland, with an extreme environment of drought in the middle and lower reaches. Water recourse was difficult to meet the local economic

16、development and ecological balance, the historical water affairs contradiction was very serious. With agriculture large-scale development in middle reaches of Hei River, water requirement has been increasing and the water quantity flowing into the lower of it was sharp decreased, which made river ch

17、annel was with no flux, lakes was dry and the level of the under ground water was decline and the ecological environment in the lower of Hei River was degenerated further. In order to keep within limits of ecological environment decline trend in the lower of Hei River and resolve the prominent water

18、 affairs contradiction, water regulation was carried out in 1999. After the 9 years of water regulation in Hei River, water was supplemented effectively to the lower lakefronts area, the biodiversity was obviously increased and the ecological environment was step recovered. East Juyanhai Lake is the

19、 Tail-stream of Hei River, timely and accurately understanding the water surface area of it is very important for water regulation evaluation and ecological environment recovery analysis.The water surface area of East Juyanhai Lake was surveyed by field artificial method now, which was difficult and

20、 the surveyed result was limited by local condition of sparse population, desert bordering and hard environment. Additionally, it needs a lot of work and a large amount of human and material resources with field artificial method. Remote sensing is quick, not limited by ground condition and has long

21、-time dynamic monitoring ability, so it has some special advantages not being replaced by other monitoring method. Remote sensing technology has been used on ecology monitoring and achieved remarkable effect. Qiao-Xixian obtained Landuse data in the lower of Hei River with ETM images and studies wat

22、er resource, vegetation and ecological environment recovery in East and West Juyanhai Lakes after water regulation. Guo-Ni evaluated ecological environment recovery effect after water regulation in Hei River. Remote Sensing Application Center & Instrument Institute monitored water injection conditio

23、n based on MODIS images after the first water regulation in 2002.MODIS image is an important data to do long period time and sequential monitoring for it is very convenient to obtained and with short repeat period. However with the lower resolution, its interpretation result has low accuracy, so it

24、has some difficulties when used in practice. The images with high resolution can describe the features detail information and can obtain water surface area accurately to get high interpretation precision, so the water surface area interpreted on it can be considered as a true value to verify the res

25、ult interpreted by MODIS. Analyzing the interpretation errors between the MODIS image and the high resolution image, it has a big signification for the MODIS image to do water surface area monitoring of East Juyanhai Lake.In this paper, water surface area of East Juyanhai Lake was interpreted separa

26、tely based on MODIS images and high resolution images, and the results were compared. The water surface monitoring method on East Juyanhai Lake was further discussed based on remote sensing data.Figure 1 The method flow map of this study2Study data and areaEast Juyanhai Lake lies in the north of Eej

27、ina in Alaskan city, Inner Mongolia Autonomous Rregion. The area of the lake was 35 km2 during 19281932 when the Sino-Swedish Expedition team investigated west north of China. The area was still 35.5 km2 by 1958. Because water from the upper reaches of Hei River reduced, East Juyanhai Lake had been

28、dried up for six times since 1949, which caused ecological environment deterioration. Since water is allocated in Hei River, water of Hei River reached EAST Junyanhai Lake again and the water surface appeared. The ecological environment has been restored. Ten high resolution images have been used in this study, including multi-band data of TM, CBERS 2 and pan data of P5 （table 1）. The MODIS 1B data have also been collected in the same day of the high resolution images. Besides that, the observed areas of East Juyanhai by hydrologic