松嫩平原西部湖泊与水库/坑塘动态变化及驱动因素分析

松嫩平原西部湖泊与水库/坑塘是保障区域农牧业经济发展和生态安全的重要条件。为掌握松嫩平原西部湖泊与水库/坑塘在1990-2013年间的变化信息,为区域生态环境建设及防洪减灾提供数据库支撑,该文基于Landsat TM(Thematic Mapper)、ETM+(Enhanced Thematic Mapper Plus)、OLI(Operational Land Imager)和中国环境资源卫星(HJ,Huanjing)多时相遥感影像,利用e Cognition软件采用面向对象分类方法提取1990年、2000年和2013年湖泊和水库/坑塘分布信息,探讨1990-2013年间松嫩平原西部湖泊和水库/坑塘蓄水面积和数量的变化及驱动因素。结果显示:研究区范围内实际蓄水面积大于20 km2的湖泊有20个,黑龙江和吉林两省分别有17和3个;面积大于20 km2的水库有9个,其中7个位于黑龙江。松嫩平原西部湖泊与水库/坑塘主要分布于沿嫩江和松花江两侧,最大湖泊为查干湖、最大水库为月亮泡水库。研究区内1990年、2000年和2013年的湖泊面积分别为3 633.2、3 016.3和2 534.0 km2,水库/坑塘的面积分别为885.9、797.1、1 433.2 km2。气候变化叠加人类活动影响的背景下,1990-2013年间湖泊数量呈现明显减少而水库/坑塘呈现明显增加的趋势。湖泊蓄水总面积呈现明显下降趋势,共减少1 099.2 km2,2013年总面积为2 534.0 km2;而水库/坑塘蓄水总面积呈现先降低后增加的趋势,1990-2000年减少88.8 km2,2013年又增至1 433.2 km2,23 a共增加547.3 km2。气候因素是变化的重要原因,尤其对于水库/坑塘,气温和降水在不同时间段的变化趋势与之变化非常吻合。而对于湖泊的变化,明显增加的耕地和运河/沟渠、避免洪灾采取的相关措施等人为因素的影响更明显。由此可见,气候因子变化和农业活动及相关的水利工程与调控措施是影响松嫩平原西部湖泊和水库/坑塘蓄水面积与数量的重要因素。该文对湖泊与水库/坑塘水资源的长时间序列统计和分析结果,可为松嫩平原西部生态保护与修复提供数据支撑,为区域可持续发展提供科学依据。

Analysis of dynamics and driving forces of lakes and reservoirs in western Songnen Plain

Abstract: Lakes and reservoirs are important factors for ensuring the development of regional agricultural and animal husbandry economy and ecological security. In order to understand the changes and main driving factors of lakes and reservoirs in the western Songnen Plain from 1990 to 2013, based on the multiple-temporal images of Chinese HJ (Huanjing) and Landsat TM (thematic mapper), ETM+ (enhanced thematic mapper plus) and OLI (operational land imager) satellites, the spatial distributions of lakes and reservoirs in 1990, 2000 and 2013 were extracted using object-oriented classification method with eCognation software. Validated by a large number of field surveys, Google Earth and high-definition earth observation satellite (Gaofen-1), the accuracy of extracted results by users reached 95%, which could be applied to scientific research. Furthermore, this study investigated the area and number change of lakes and reservoirs and the driving forces of these changes from 1990 to 2013 in the western Songnen Plain. Referring to those with the area of more than 20 km2, there were a total of 20 lakes, 17 in Heilongjiang Province and 3 in Jilin Province, and a total of 9 reservoirs among which only 2 in Jilin Province. Spatially, lakes and reservoirs in study area were mainly distributed on the both sides along the Nenjiang River and Songhua River, among which the Chagan Lake and the Yueliangpao Reservoir had the largest area, respectively. Areas of lakes in 1990, 2000 and 2013 were 3633.2, 3016.3 and 2534.0 km2, and those of reservoirs were 885.9, 797.1 and 1433.2 km2, respectively. Under the combined effects of climate change and human activities, the number of lakes showed an obvious decreasing trend while that of reservoirs was opposite during the past over 20 years. From 1990 to 2013, the area of the lakes totally decreased by 1099.2 km2 and the existing area of lakes was 2534.0 km2 in 2013; the area of reservoirs decreased by 88.8 km2 at the first 10 years, and then increased to 1433.2 km2 in 2013, having a total increase of 547.3 km2. Climate factors were the important reasons for the above mentioned changes of lakes and reservoirs in the western Songnen Plain. Especially, slightly increased temperature and decreased precipitation between 1990 and 2000 and the opposite change of them from 2000 to 2013 were completely consistent with the variation of reservoirs. While for the changes of lakes, agricultural activities may be more influential than temperature and precipitation, which could be proved by obviously increased farmland and canal, and control expansion measures to avoid flood during the past over 20 years although several new reservoirs were built as well. It meant that more water had to be used for irrigation. In conclusion, climate factors, agricultural activities, and related water conservancy projects and control measures are the main and important influencing factors for the change of lakes and reservoirs in the western Songnen Plain, China. The observed results with a long time sequence in monitoring the lakes and reservoirs in study area can provide data support for ecological protection and restoration and scientific basis for regional sustainable development.