4 years ago

Prognosis and mitigation strategy for major landslide-prone areas Varunavat Parvat landslide in Uttarkashi

Prognosis and mitigation strategy for major landslide-prone areas A case study of Varunavat Parvat landslide in Uttarkashi township of Uttarakhand (India)

entrenchment of its

entrenchment of its proximal part near Kharuwan village can be attributed to Kharuwan-Badethi anticlinal axis and fault (Figure 4). At Matli village a NE-SW trending fault is observed and another N-S trending fault has been traced in the further west of Matli. Study of satellite images from Indian Remote Sensing satellites (IRS-1D & IRS P6) has revealed the existence of three prominent lineaments trending NE-SW NW-SE and N-S direction. Prominent among these are NE-SW trending Mandwa-Ujeli lineament, Gyansu lineament and NW-SE trending Chamkot lineament. NE-SW trending Mandwa – Ujeli lineament controls the Bhagirathi river course in the south of Khand village upto Uttarkashi township, where it terminates against Baragadi anticlinal axis and fault, whereas, in the east of Khand village this lineament intersects the axis of Kot syncline. Gyansu lineament is traced in the western part of Uttarkashi township along Gyansu Nala (seasonal stream) and is characterised by narrow valley of Gyansu Nala. The excessive mass wastage on the valley walls of Gyansu Nala, in the form of small active slides developed within the larger old slide zones and entrenchment of the proximal part of Gyansu Fan and its NE-SW disposition are strong evidences of the existence of Gyansu lineament (Figures 3 and 4). Geomorphology Geomorphic set up of the area is defined by moderate to highly dissected hills, structurally controlled ridges and river terraces of Bhagirathi and Indravati rivers with colluvial deposits and a number of alluvial fans developed at the junction of hills and river terraces. However, large active and old slide zones are conspicuous in the area and many alluvial fans deposited by small tributary streams (of Bhagirathi) are Prognosis and mitigation strategy 631 Figure 4. Morphotectonic map of Varunavat Parvat and surrounding area of Uttarkashi township

DPM 17,5 632 Figure 5. Landslide map of Varunat Parvat area Plate 7. View of Varunavat Parvat about one and a half decade back superposed over the vast terraces of Bhagirathi river. Varunavat Parvat has witnessed extensive development of colluvial deposits due to gravity transport on its moderate to steep slopes (Figures 4 and 5; Plates 1, 7 and 8). Salra village in the NW of Uttarkashi township is located over colluvium and the southern slope aspects of Varunavat Parvat (towards Bhagirathi river) also have large colluvial deposits. The northeastern part of Uttarkashi township in the north of National Highway is located over the distal part of colluvial fan deposits (Figure 5). Furthermore, on the southern bank of Bhagirathi river the villages of Jaspur and Silyana are located over colluvium. On the northern bank of the river the alluvial fans of Gyansu and Padull are conspicuous and distal part of both these fans have habitations (Figure 4). On the southern bank of Bhagirathi river the alluvial fans are developed around Pokhri, Dang and Kotyalgaon. In the east of Uttarkashi township the villages of Ujeli and Tiloth are located over terrace deposits. Major part of Uttarkashi township is also located over the terrace deposits. Joshiyara,

Disaster management strategy for potential slide zones of Kumarkhera in Narendra Nagar township of Tehri Garhwal district, Uttarakhand, India