Sains Ma1aysiana 28: 87-99 (1999)                                                                                                           Sains Bumi/

                                                                                                                                                                         Earth Science

Geomorphological Assessment on Potential Landslide

Hazard in the Ebbw Valley, Gwent,

South Wales United Kingdom

Zulfahmi Ali Rahman

Program Sains Sekitaran

Fakulti Sains Sumber Alam

Universiti Kebangsaan Malaysia

43600 UKM Bangi, Selangor D.E. Malaysia

ABSTRACT

These works were carried out in order to collect the available information and to get general understanding upon the landslide occurrences and their characteristics. The landsliding problems in the South Wales are the main issue and being continually studied for minimizing the impact of coal mining activity and urbanization schemes. The preliminary study had been conducted and then followed by the preparation of the geomorphological maps of the study area in terms of their potential and contribution to the landslide problems. The landslide prone areas are closely related to the highly slope gradient ranging from 21º to over 35º and largely controlled by the geological underlying and human activity of coal mining along the valley flank. On the hilltop and valley side areas, the tension cracks have been gradually developed contributing to rockfalls largely influenced by the existing fault and joint structures. Evidences of mass movement comprise lobes of superficial deposits, rockfalls and coal fragments were found at the lower part of the valley areas. Water seeps through slope materials and being driven together to the toe of the slope.

ABSTRAK

Kajian ini telah dilakukan bertujuan untuk mengumpul maklumat bagi memberikan kefahaman berhubung dengan taburan dan ciri-ciri kegagalan cerun. Masalah tanah runtuh di South Wales adalah merupakan isu utama dan kajian giat dijalankan bagi tujuan meminimumkan kesan impak aktiviti perlombongan arang batu dan perbandaran. Kajian awal telah dilakukan dan diikuti dengan penyediaan peta-peta geomorfologi yang mengambilkira potensi dan sumbangan terhadap kejadian tanah runtuh. Kawasan cenderung mengalami kegagalan cerun amnya berkait rapat dengan sudut cerun berjulat antara 21º- lebih 35º dan dikawal oleh kedudukan geologi tempatan dan aktiviti perlombongan arang batu di kawasan lereng sepanjang lembah. Rekahan permukaan diperhatikan di bahagian tebing tinggi yang menunjukkan perkembangan dan menyumbang kepada kejadian runtuhan batuan. Keadaan ini dikawal oleh struktur sesar dan sistem kekar yang tinggi pada batuan yang tersingkap. Bukti dan kesan pergerakan jisim terdiri dari cuping-cuping (lobus) endapan permukaan, runtuhan batuan dan pecahan arang batu yang ditemui di kawasan berdekatan dataran lembah. Air berupaya meresap melalui endapan cerun dan membawa bersama bahan hakisan ke kawasan kaki cerun.

RUJUKAN/REFERENCES

Barclay, W.J. 1989. The Geology of the South Wales Coalfield, part II, the Country Around Abergavenny. Memoir of Geology Survey of England and Wales.

Halcrow William. 1973a. Abertillery New Mines, Regulation 12 Report on the Active Classified Tip 572 (South Griffith Tip). Report for National Coal Board, South Wales Area.

Halcrow William. 1973b. Abertillery New Mines, Regulation 12 Report on the Active Classified Tip 573 (Roseheyworth Maclane Tip). Report for National Coal Board, South Wales Area.

Hansen, A. 1984. Landslide Hazard Analysis. In D. Brunsden and D.B Prior (Eds). Slope Instability. John Wiley & Sons Ltd. pp. 523-602

Harrisson, A.C.F. 1995. Review and Analysis of the Factor Effecting Ground Movement at Westside, Blaina, Gwent. Unpublished MSc. Thesis

Rouse, W.C, & Farhan, Y.I. 1976. Threshold Slopes in South Wales. Quart. J. Engineering Geol. 9: 327-338.