基于MODIS数据的湿地退化监测方法研究——以扎龙湿地为例

Study on Monitoring Method of Wetland Degradation Based on MODIS Data——A Case Study of Zhalong Wetland

由于水资源的缺乏而导致湿地的萎缩和退化是目前我国湿地面临的主要生态环境问题之一.依据湿地生态系统的特征和湿地蒸散发的能量与水分平衡原理,本文构建了湿地水分亏缺指数(WWDI:Wetland Water Deficit Index)对湿地退化进行遥感动态监测,并以扎龙湿地为例,探讨了该方法的可行性.具体步骤是:首先,在地表能量平衡系统模型的基础上,利用MODIS遥感数据产品获得湿地蒸散模型的各项参数,并结合气象数据对湿地的实际蒸散进行估算;采用Penman-Monteith公式估算湿地的潜在蒸散量;在此基础上,利用湿地实际蒸散量和潜在蒸散量之间的比值关系,来反映湿地因缺水而退化的程度和空间分布状况.最后利用该方法对2009年8月29日扎龙湿地的水分亏缺状况进行了实证研究,讨论了该方法进行湿地退化遥感监测的优缺点.

The shrinkage and degradation of wetlands caused by water shortage is one of the major ecological en- vironment problems in China now. According to wetland ecosystem characteristics and the principles of energy and water balance of wetland evapotranspiration, a wetland water deficit index （WWDI） is constructed to per- form a remote sensing dynamic monitoring on wetland degradation. Taking the wetland of Zhalong as an example, the feasibility of the method is discussed. Firstly, based on the principles of surface energy balance system mod- el, the parameters of the wetland evapotranspiration model are obtained by MODIS remote sensing digital prod- ucts, which are then combined with the meteorological data to make an estimation on the actual evapotranspira- tion of the wetlands. Secondly, the Penman - Monteith equation is adopted to estimate the potential evapotranspi- ration of the wetlands. Then, the ratio between the actual and the potential evapotranspiration is used to reflect the degeneration degree and spatial distribution of the wetland caused by water shortage. Finally, the method is employed to study water deficit conditions of Zhalong wetland on August 29, 2009. The advantages and disad- vantages of applying the method to remote sensing monitoring of wetland degradation are also discussed.