Sediment load decline and increased erosion linked to human activities in the Cauvery delta, India

IF 5.7 1区农林科学 Q1 GEOSCIENCES, MULTIDISCIPLINARY

Catena Pub Date : 2025-10-03 DOI:10.1016/j.catena.2025.109486

Sumit Das , Harshada Jadhav , Aditi Roy , Gianvito Scaringi

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Abstract

The Cauvery River is a crucial drainage system in Peninsular India, supporting the region’s agriculture and ecological systems. However, it remains poorly studied when it comes to long-term sediment dynamics. This study presents the first comprehensive assessment of 45 years (1973–2018) of suspended sediment trends across the Cauvery basin, combining non-parametric methods (Mann-Kendall test, Pettitt test, double-mass curves), disentangling drivers of trends and assessing downstream impacts. Results indicate alarming consistent sediment reductions at 13 of 14 stations, with 12 showing statistical significance (p < 0.05) over the past two decades. The sharpest decline occurred in the middle reach (Biligundulu: 33.79 × 10³ t yr⁻¹), followed by the terminal station Musiri (13.73 × 10³ t yr⁻¹). From 2000 to 2018, the average sediment load at Musiri decreased by 68 %, while upstream tributaries Hemavati and Shimsha showed 71 % and 76 % decline, respectively. These declines exceeded those reported in larger rivers such as the Godavari or Krishna. Importantly, long-term rainfall showed no significant trends, ruling out climate as a primary driver. Change-point analysis identified abrupt sediment reductions during the mid-1990s to early 2000s, coinciding with NDVI-linked vegetation health recovery post-1990 and dam construction peaks. Land-use shifts (1985–2005) led to a decrease in forest and agricultural areas by 8 % and 3.5 %, respectively, while built-up areas expanded by 140 %, likely leading to an initial increase in sediment load. Sediment starvation caused severe coastal erosion in the Cauvery delta, with over 300 m of retreat at the estuary and localised recession exceeding 500 m. Previously stable lagoons are now experiencing intensified erosion and reflecting deltaic vulnerability. These findings provide a pivotal baseline for sediment-starved deltas in India, urging strategic basin management to mitigate irreversible submersion risks under rising sea level.

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印度高韦里三角洲泥沙负荷下降和侵蚀加剧与人类活动有关

高韦里河是印度半岛重要的排水系统，支撑着该地区的农业和生态系统。然而，当涉及到长期泥沙动力学时，它的研究仍然很少。本研究结合非参数方法（Mann-Kendall检验、Pettitt检验、双质量曲线），首次综合评估了45年来（1973-2018年）整个Cauvery盆地的悬浮泥沙趋势，揭示了趋势的驱动因素，并评估了下游影响。结果表明，在过去20年中，14个站点中有13个站点的沉积物减少幅度惊人，其中12个站点具有统计学意义（p < 0.05）。下降幅度最大的是中游（比里贡都鲁：33.79 × 103 t yr−1），其次是终点站Musiri （13.73 × 103 t yr−1）。2000 - 2018年，Musiri的平均含沙量下降了68%，而上游支流Hemavati和Shimsha分别下降了71%和76%。这些下降超过了戈达瓦里河或克里希纳河等较大河流的报道。重要的是，长期降雨没有显示出明显的趋势，排除了气候是主要驱动因素的可能性。变化点分析发现，在20世纪90年代中期至21世纪初，沉积物突然减少，与ndvi相关的1990年后植被健康恢复和大坝建设高峰相吻合。土地利用变化（1985-2005）导致森林和农业面积分别减少了8%和3.5%，而建成区面积扩大了140%，可能导致泥沙负荷最初增加。泥沙饥饿造成了高韦里三角洲严重的海岸侵蚀，河口退缩超过300米，局部退缩超过500米。以前稳定的泻湖现在正在经历加剧的侵蚀，反映出三角洲的脆弱性。这些发现为印度缺乏沉积物的三角洲提供了关键的基线，敦促战略流域管理减轻海平面上升带来的不可逆转的淹没风险。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Catena 环境科学-地球科学综合

CiteScore

10.50

自引率

9.70%

发文量

816

审稿时长

54 days

期刊介绍： Catena publishes papers describing original field and laboratory investigations and reviews on geoecology and landscape evolution with emphasis on interdisciplinary aspects of soil science, hydrology and geomorphology. It aims to disseminate new knowledge and foster better understanding of the physical environment, of evolutionary sequences that have resulted in past and current landscapes, and of the natural processes that are likely to determine the fate of our terrestrial environment. Papers within any one of the above topics are welcome provided they are of sufficiently wide interest and relevance.