Rivers are essential to human livelihoods and agricultural production, yet human usage and irrigation are jeopardizing river sustainability. It is thus crucial to investigate the fine-scaled spatiotemporal dynamics of anthropogenic pressures on rivers. Most research, however, is conducted at the grid-scale, which impedes detailed investigations. In this study, by tracking anthropogenic pressures at the scale of river reaches (the length of river between river confluences) in South and Southeast Asia from 1990 to 2014, we provide new insights into anthropogenic pressures on river reaches using a simple and straightforward approach. We selected human usage (represented by built-up area) and irrigation (represented by irrigated area) as two fundamental indicators of anthropogenic pressure. We divided the study area into 5 5 km grids and calculated anthropogenic pressures on each grid to its nearest river reach. Pressures were calculated as the ratio of built-up and irrigated area to the distance between grids and reaches. Groundwater was also included to adjust for additional irrigation-induced pressures on reaches. Anthropogenic pressures on each reach were then calculated by summing pressures from the two indicators of all grids attached to it. Results indicate that >50% of reaches are affected by anthropogenic activities and that average pressures increase by ∼15% from 1990 to 2014, with hotspots concentrated in eastern Pakistan and northern India. Irrigation is the dominant pressure on ∼33% of reaches, while human usage is dominant for ∼24% of reaches. Anthropogenic pressures within transboundary river basins vary longitudinally, increasing as distance from the ocean declines. Pressures also vary significantly with reach size. Although large rivers suffer from greater anthropogenic pressures, they are rising more rapidly for small rivers. Empirically, this study reveals the increasing and heterogeneous nature of anthropogenic pressures on river reaches in South and Southeast Asia. Methodologically, it suggests that reach-scale river sustainability assessment can serve as a promising approach for researching and managing regional and transboundary rivers.

河流对于人类的生计和农业生产至关重要，但是人类的使用和灌溉正在危害河流的可持续性。因此，研究人为压力在河流上的精细时空动态至关重要。但是，大多数研究是在网格规模上进行的，这妨碍了详细的研究。在这项研究中，通过追踪1990年至2014年南亚和东南亚的河段规模（河道汇合之间的河段长度）的人为压力，我们使用简单明了的方法提供了关于河段人为压力的新见解。我们选择了人类使用（以建筑面积表示）和灌溉（以灌溉面积表示）作为人为压力的两个基本指标。我们将研究区域划分为5个5公里的网格，并计算了每个网格上最接近河流的人为压力。压力计算为堆积面积和灌溉面积与栅格与河段之间的距离之比。地下水也包括在内，以调节因灌水引起的附加压力。然后，通过将与之相连的所有网格的两个指示器的压力相加，得出每个河段的人为压力。结果表明，> 50％的河段受到人为活动的影响，从1990年到2014年，平均压力增加了约15％，热点集中在巴基斯坦东部和印度北部。灌溉是约33％的河道的主要压力，而人类使用则是约24％的河道的主要压力。跨界流域内的人为压力沿纵向变化，随着距海洋距离的减小而增加。压力也随着触及范围的变化而显着变化。尽管大型河流遭受更大的人为压力，但对于小型河流，它们的上升速度更快。从经验上讲，这项研究揭示了南亚和东南亚河道人为压力的增加和非均质性。从方法上讲，它表明河川规模的可持续性评估可以作为研究和管理区域和跨界河流的有前途的方法。这项研究揭示了在南亚和东南亚，人为压力在河道上的增加和异质性。从方法上讲，它表明河川规模的可持续性评估可以作为研究和管理区域和跨界河流的有前途的方法。这项研究揭示了在南亚和东南亚，人为压力在河道上的增加和异质性。从方法上讲，它表明河川规模的可持续性评估可以作为研究和管理区域和跨界河流的有前途的方法。