Data for: A generalized area-based framework to quantify river mobility from remotely sensed imagery

Rivers are the primary conduits of water and sediment across Earth's surface. In recent decades, rivers have been increasingly impacted by climate change and human activities. The availability of global-coverage satellite imagery provides a powerful avenue to study river mobility and quantify the impacts of these perturbations on global river behavior. However, we lack remote sensing methods for quantifying river mobility that can be generally applied across the diversity of river planforms (e.g., meandering, braided) and fluvial processes (e.g., channel migration, avulsion). Here, we upscale area-based methods from laboratory flume experiments to build a generalized remote sensing framework for quantifying river mobility. The framework utilizes binary channel-mask time series to determine time- and area-integrated rates and scales of river floodplain reworking and channel-thread reorganization. We apply the framework to numerical models to demonstrate that these rates and scales are sensitive to specific river processes (channel migration, channel-bend cut-off, and avulsion). We then apply the framework to natural migrating and avulsing rivers with meandering and braided planforms. Results show that our area-based framework is an accurate method to quantify river mobility at reach- to landscape-scales, and is largely insensitive to spatial and temporal biases that can arise in traditional mobility metrics. Our work provides a framework for investigating global controls on river mobility, testing hypotheses about river response to environmental gradients, and quantifying the timescales of terrestrial organic carbon cycling.

河流是地球表层水与沉积物输运的主要通道。近数十年来，河流日益受到气候变化与人类活动的双重影响。全球覆盖的卫星遥感影像为研究河流活动性（river mobility）、量化这些扰动对全球河流行为的影响提供了强有力的研究途径。然而，当前仍缺乏可普遍适用于各类河流平面形态（例如曲流（meandering）、辫状（braided））与河流过程（例如河道迁移、决口改道（avulsion））的河流活动性量化遥感方法。在此背景下，本研究将实验室水槽实验中的基于面积的方法进行尺度升级，构建了一套通用的河流活动性量化遥感框架。该框架利用二值化河道掩码时间序列（binary channel-mask time series），可计算得到河流漫滩改造与河道带重组的时间积分速率与特征尺度。我们首先将该框架应用于数值模型，证明上述速率与特征尺度对特定河流过程（河道迁移、河道裁弯、决口改道）具有显著敏感性。随后将该框架应用于具有曲流与辫状平面形态的自然迁移、改道河流。研究结果表明，本研究所提出的基于面积的框架可精准量化河段至景观尺度的河流活动性，且基本不受传统活动性指标中可能出现的时空偏差影响。本研究为探究河流活动性的全球控制因素、验证河流对环境梯度响应的相关假说，以及量化陆地有机碳循环的时间尺度提供了可靠的研究框架。