洪湖是湖北省最大的湖泊,具有调蓄、灌溉、供水、渔业、物种保护、航运、旅游等多种功能,是长江中下游典型的大型浅水型湖泊。传统的设点监测费力、费时,随着遥感技术和手段的进步,遥感反演洪湖叶绿素a浓度成为技术上可能。利用2005年至2010年6年监测数据与同期MODIS数据进行统计分析,研究业务上进行洪湖叶绿素a含量反演的可能性,结果表明:当叶绿素a含量比较高时,它成为影响湖中NDVI指数的主要因素,当浓度较低时,它与NDVI指数相关性差,表明它不是主要要素;通过分析不同时段两者统计关系结果为:12~2月因藻类浓度比较小,叶绿素a浓度低,加上其它要素干扰湖中NDVI指数,监测数据与同期MODIS数据中NDVI指数相关性比较低(也是极显著相关),其它时间都有较好的相关性(相关系数都高于0.85),研究表明:运用MODIS数据中的NDVI指数能准确监测洪湖叶绿素a含量。并提出相应的业务处理流程与方法。
HongHu is the biggest lake in Hubei province.Its main function is water storage and adjustment,irrigation,fishing,shipping and tourism,and it belongs to shallow type lakes.Besides being time-consuming and expensive,conventional methods of studying water quality(e.g.water sampling by boat) frequently fail to adequately represent heterogeneous and patchy areas.Remote sensing techniques,which have the inherent ability to provide spatial and temporal information about water,may be the only viable way to effectively monitor water quality in lakes.This paper discusses the feasibility analysis of retrieval Chlorophyll-a concentration in HongHu Lakes using MODIS Data from 2005-2010.The result indicates that the Chlorophyll-a concentration is the main factor of influencing NDVI changes when Chlorophyll-a concentration value is high.This study also gives difference reversion format by various seasons.All indicates the method using NDVI value to retrieval Chlorophyll-a concentration is corrected.Finally,the detail process and methods on the business were put forward.