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首页> 外文期刊>Freshwater science >Landsat imagery reveals declining clarity of Maine's lakes during 1995-2010
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Landsat imagery reveals declining clarity of Maine's lakes during 1995-2010

机译：Landsat影像揭示了1995-2010年期间缅因州湖泊的清晰度下降

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摘要

Water clarity is a strong indicator of regional water quality. Unlike other common water-quality metrics, such as chlorophyll a, total P, or trophic status, clarity can be accurately and efficiently estimated remotely on a regional scale. Satellite-based remote sensing is useful in regions with many lakes where traditional field-sampling techniques may be prohibitively expensive. Repeated sampling of easily accessed lakes can lead to spatially irregular, nonrandom samples of a region. Remote sensing remedies this problem. We applied a remote monitoring protocol we had previously developed for Maine lakes >8 ha based on Landsat satellite data recorded during 1995-2010 to identify spatial and temporal patterns in Maine lake clarity. We focused on the overlapping region of Landsat paths 11 and 12 to increase availability of cloud-free images in August and early September, a period of relative lake stability and seasonal poor-clarity conditions well suited for annual monitoring. We divided Maine into 3 regions (northeastern, south-central, western) based on morphometric and chemical lake features. We found a general decrease in average statewide lake clarity from 4.94 to 4.38 m during 1995-2010. Water clarity ranged from 4 to 6 m during 1995-2010, but it decreased consistently during 2005-2010. Clarity in both the northeastern and western lake regions has decreased from 5.22 m in 1995 to 4.36 and 4.21 m, respectively, in 2010, whereas lake clarity in the south-central lake region (4.50 m) has not changed since 1995. Climate change, timber harvesting, or watershed morphometry may be responsible for regional water-clarity decline. Remote sensing of regional water clarity provides a more complete spatial perspective of lake water quality than existing, interest-based sampling. However, field sampling done under existing monitoring programs can be used to calibrate accurate models designed to estimate water clarity remotely.
机译：水的净度是区域水质的有力指标。与其他常见的水质指标（例如叶绿素a，总P或营养状态）不同，可以在区域范围内远程准确，高效地估算清晰度。基于卫星的遥感技术在许多湖泊地区都非常有用，在这些地区，传统的野外采样技术可能过于昂贵。重复采样易于访问的湖泊可能会导致某个区域的空间不规则，非随机采样。遥感解决了这个问题。我们根据1995-2010年间记录的Landsat卫星数据，应用了先前针对大于8公顷的缅因州湖泊开发的远程监控协议，以识别缅因州湖泊的净空时空格局。我们专注于Landsat路径11和12的重叠区域，以提高8月和9月初的无云图像的可用性，这是一个相对湖泊稳定且季节性较差的条件，非常适合年度监测。根据形态和化学湖泊特征，我们将缅因州分为3个区域（东北，中南部，西部）。我们发现1995年至2010年期间，全州平均湖泊平均清晰度从4.94下降至4.38 m。在1995-2010年期间，水的清晰度介于4到6 m之间，但在2005-2010年期间却持续下降。东北和西部湖泊区域的净度分别从1995年的5.22 m降至2010年的4.36和4.21 m，而中南部湖泊区域的湖泊净度（4.50 m）自1995年以来就没有变化。采伐木材或分水岭形态可能是造成区域净水度下降的原因。与现有的基于兴趣的采样相比，对区域水质清晰度的遥感提供了更完整的湖泊水质空间视角。但是，在现有监控程序下进行的现场采样可用于校准旨在远程评估水净度的精确模型。

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