The Ganga basin represents a network of complex river systems, experiencing rapid changes due to natural and anthropogenic activities. The Alaknanda and Ramganga rivers lying adjacent to each other in the NW Himalayas represent two unique sub-basins of River Ganga having distinct physiography, climate, physical and chemical processes and land-use patterns. The present study employs mineral magnetic technique to unravel the controlling factors that influence alteration in sediment source, composition and transport processes along the routing pathway. The variations in magnetic mineralogy and concentrations provide a suite of information discriminating the sediment sources and transport mechanisms. The results show dominant ferrimagnetic mineral assemblage in the Alaknanda basin whereas an admixture of ferrimagnetic and antiferromagnetic minerals in the Ramganga basin. The high spatial variability in concentration of magnetic minerals in Alaknanda basin indicates the role of felsic and mafic rocks weathering as well as anthropogenic contribution in sediment magnetism. The tributaries flowing through peculiar lithology and anthropocentric polluted areas influence the magnetism of main river channels. The loss of mafic weathering signatures in downstream sediment of the Ramganga floodplains is due to reconstruction of man-made dam at Kalagarh, which traps upstream sediment load. The magnetically hard antiferromagnetic minerals in sediments of Ramganga floodplain region compared to mountainous region indicate its possible source either from pollution due to extensive land use for industrial and agricultural practices or from more oxidative weathering under low sedimentation and low energy environment. The findings signify new aspects of sediment sources, accentuate anthropogenic perturbation and demonstrates the applicability of environmental magnetism for developing sediment dispersal-mixing and pollution model for the larger Ganga basin.

恒河盆地代表着复杂的河流系统网络，由于自然和人为活动而迅速变化。西北喜马拉雅山脉彼此相邻的阿拉克南达河和拉姆甘加河代表着恒河的两个独特子流域，其生理，气候，物理和化学过程以及土地利用方式各不相同。本研究采用矿物磁技术来揭示影响沉积物来源，组成和沿路径路径的运输过程变化的控制因素。磁性矿物学和浓度的变化提供了一整套区分沉积物来源和输送机制的信息。结果表明，Alaknanda盆地中主要的亚铁磁性矿物组合，而Ramganga盆地中的亚铁磁性和反铁磁性矿物的混合物。Alaknanda盆地中磁性矿物浓度的高度空间变异性表明，长英质和镁铁质岩石风化的作用以及人为因素对沉积物磁性的影响。流经特殊岩性和人类中心污染区的支流影响主要河道的磁性。Ramganga洪泛区下游沉积物中铁素体风化特征的丧失是由于在卡拉加尔（Kalagarh）人工大坝的重建，该大坝捕获了上游沉积物的负荷。与山区相比，Ramganga洪泛区的沉积物中具有磁性的反铁磁性矿物表明，其可能的来源可能是由于工业和农业实践中广泛使用土地而造成的污染，也可能是由于低沉积和低能耗环境下的氧化性风化作用更大。这些发现标志着沉积物来源的新方面，加剧了人为扰动，并证明了环境磁在开发大型恒河盆地沉积物分散混合和污染模型方面的适用性。