Morphometry of alluvial fans in an alpine valley basin in southeast Tibet: Spatial heterogeneity, controls, and implications

IF 5.7 1区农林科学 Q1 GEOSCIENCES, MULTIDISCIPLINARY

Catena Pub Date : 2025-02-08 DOI:10.1016/j.catena.2025.108799

Pan Han , Guo-An Yu

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引用次数: 0

Abstract

The morphometry of alluvial fans is a fundamental yet significant aspect of understanding fan dynamics and controls, offering potential benefits for fan type discrimination and mitigation of geo-hazards such as flash floods and debris flows. However, alluvial fans in alpine regions have received considerably less attention than their counterparts in non-alpine areas, despite their importance. Using Google Earth Pro, remote sensing images, targeted field surveys, and statistical analysis, we examine the morphometry, spatial heterogeneity along with underlying causes, and primary types (fluvial, debris-flow, and colluvial) of alluvial fans in the Parlung Tsangpo Basin (PTB), a large alpine tributary basin of the Yarlung Tsangpo River (upper Brahmaputra River) characterized by deep valleys in southeastern Tibet, China, based on a dataset of 129 fan samples. Our results reveal that: (1) Significant spatial heterogeneity exists in the morphometry of alluvial fans in the PTB, particularly regarding fan area. (2) Fans exhibiting distinct morphometries correspond to different primary processes (debris flow, fluvial, or colluvial dominated), with varying links to their source basins. (3) Discriminant analysis based on three variables (fan slope, source basin area, and Melton’s R) can effectively distinguish between fan types and their primary processes. The development of alluvial fans in the PTB is collectively determined by various allogenic and autogenic factors, with primary processes and tributary-junction effects (distal confinement) acting as the main controls. The primary processes, influenced by regional relief (slope), climate (precipitation and temperature), and sediment supply conditions (volume and caliber), play an essential role in fan development, particularly regarding fan slope. In light of global climate change, new fans have been developing in the basin, while some previously stable fans have entered a new active phase. Consequently, debris flows have become a dominant primary process for alluvial fan development in PTB, driving the evolution of fan morphology.

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藏东南高寒河谷盆地冲积扇形态特征：空间异质性、控制因素及其意义

冲积扇的形态测量学是理解扇动力学和控制的一个基本而重要的方面，为扇的类型区分和减轻山洪和泥石流等地质灾害提供了潜在的好处。然而，与非高寒地区的冲积扇相比，高寒地区的冲积扇受到的关注要少得多，尽管它们很重要。利用谷歌Earth Pro、遥感影像、野外调查和统计分析等工具，对西藏东南部雅鲁藏布江（布拉马普特拉河上游）以深谷为特征的大高山支流帕隆雅鲁藏布江盆地（PTB）的冲积扇形态特征、空间异质性及其成因、主要类型（河流、泥石流和崩塌）进行了研究。结果表明：(1)PTB冲积扇的形态特征存在明显的空间异质性，特别是在扇面积上。(2)扇体表现出不同的形态特征，对应不同的原生过程（泥石流、河流或崩积为主），与源盆地的联系也不同。(3)基于扇坡、源盆面积、Melton’s R三个变量的判别分析可以有效区分扇类型及其主要过程。PTB中冲积扇的发育是由各种异体和自生因素共同决定的，其中初级过程和支流结效应（远端限制）是主要控制因素。受区域地形（坡度）、气候（降水和温度）和沉积物供应条件（体积和口径）影响的初级过程在扇发育中起着至关重要的作用，特别是在扇坡方面。在全球气候变化的背景下，盆地内新的扇体开始发育，一些先前稳定的扇体进入新的活跃期。因此，碎屑流已成为PTB冲积扇发育的主要过程，推动了冲积扇形态的演变。

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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.