多源遥感信息融合的宁夏东部湿地演变规律研究

Wetland in the eastern part of Ningxia, located in farming-pastoral ecotone and frontier region of desertification development, plays a vital role on local water resources regulation and biodiversity conservation. However, the wetland resources decrease dramatically and the ecological system becomes fragile in recent years due to excessive human disturbance and climate change. We have carried long-term monitoring of the wetland resources in this region by ground investigation combined with remote sensing data in preliminary studies. However, the dynamic monitoring far from accurate owns to the characteristics of the wetland scattered distribution, the seasonal changes and the mixed pixels of remote sensing data. Therefore, this project intends to utilize small unmanned aerial vehicles technology to access the near ground aerial data under different seasons, rainfall, human activities and other changes of the environment. Then mixed with the remote sensing data in the same period, we establish precise mathematical model for the pixels and decomposition. Based on the above methods, we accurately monitor the wetland vegetation, soil, hydrological characteristics which exhibited stronger spatial and temporal heterogeneity in the studied area for a long time series. Combined with the detailed ground survey data in nearly 10 years, the space-time evolution characteristics and laws of the wetland resources under human intervention and climate change will be studied and thus provide theoretical references and scientific basis for revealing the mechanism of wetland degradation and recovery and promote the comprehensive recovery of wetland resources in the studied region.

宁夏东部湿地位于农牧交错带与荒漠化发展的前沿地区，对当地水资源调节和生物多样性保护具有至关重要的作用。由于过度人为干扰和气候变化，近年来湿地资源急剧减少，生态系统日趋脆弱。我们前期利用地面调查结合遥感数据对该地区湿地资源进行了长期监测，但湿地分布零散、季节性变化大的特点和遥感数据的混合像元问题限制了湿地特征的准确动态监测。因此，本项目拟利用小型无人机航拍技术，获取不同季节、降雨、人为活动等变化环境条件下的近地面航拍数据，与同期中分辨率遥感数据融合，建立精确的亚像元分解模型，对研究区时空异质性较强的湿地植被、土壤、水文特征进行长时间序列的准确监测，结合近10年地面详细调查数据，研究人为干预和气候变化下湿地资源的时空演变特征与规律，为揭示研究区湿地退化与恢复机制、促进该地区湿地资源的全面恢复提供理论参考和科学依据。

湿地资源对干旱半干旱地区的生物多样性保护、水资源调节和当地群众的生产生活具有极为重要的意义，同时受气候变化和人为干扰的显著影响，近年来呈现破坏和恢复并存的复杂现状。为科学保护和可持续利用脆弱的湿地资源，必须对其时空分布规律进行精确监测。项目研究内容：（1）基于近地面遥感的湿地高分影像获取和地物精确分类方法；（2）长时序多光谱影像的多元亚像元分解模型建立；（3）研究区湿地资源时空分布规律及其驱动因素。项目成果：（1）以地处毛乌素沙地边缘的宁夏哈巴湖国家级自然保护区湿地为研究对象，利用高分辨率无人机航摄影像，基于面向对象的图像分割方法和决策树分类法获取了研究区典型湿地的土地利用精确分类数据；（2）融合多光谱卫星遥感影像和高分辨率土地利用分类数据，建立了不同湿地地物端元的光谱特征数据库和适宜尺度的线性回归模型；（3）结合干旱半干旱地区湿地地物组成与分布特点，建立了基于水域、土壤、植被三个端元的多光谱数据亚像元分解模型，并反演了保护区湿地1989年以来的水域面积、植被覆盖度数据，对湿地资源的时空变化特征进行了深入分析。项目研究成果对干旱半干旱地区高时空异质性湿地地物特征的精确提取和制图提供了可靠的方法；为脆弱湿地生态系统的科学保护、管理和可持续利用提供了理论支撑。