Prevention and Management

Several ways of prevention and management, many with general applicability and the others of site specific nature, are employed worldwide. Here only ecologically compatible non-engineering measures have been dealt with.

Identification of landslide prone areas: Based on soil and rock structure, rainfall patterns, slope and vegetation characteristics (evergreen, deciduous, scrub, plantations, fields, gardens etc.) and human impacts, preparation of landslide hazard zonation maps at 1:1000 scale are essential. The methodology has been already evolved by the Department of Science and Technology, Government of India, under the Natural Resources Data Management System.

Drainage correction: In the hilly areas natural drainage patterns should be studied and maintained properly without any blockage. Characteristic stream-side species are to be promoted for stream-bank protection and ecology.

Restoration of vegetation cover: A replanting programme should be undertaken giving priority for strong and deep rooted species which check erosion and withstand water-logging. Pongamia pinnata, Calophyllum inophyllum, Ficus racemes, Thespesia populnea, Barringtonia spp., Terminalia arjuna etc. may be considered for lower slopes bordering the estuarine areas. Middle and upper slopes in landslide prone areas should be planted with tree having lower biomass but stronger and deeper root networks. High biomass trees are likely to cause the weight of the overburden precipitating slope failures in future.  Minimum of 350 trees/ha would be ideal number for the hills. Locality-specific members of the natural vegetation of any given area may be given priority. The general practice  of monoculturing of trees has to be discontinued in all hazard zones.

Enhancing the scope of VFCs: The scope of the already existing village forest committees may be expanded to landslide/natural resource management as well. Necessary awareness and training programmes may be arranged for them in landslide prevention and management.

Regulations on slope cutting and quarrying: Indiscriminate slope cuttings have to be strictly regulated and engineering solutions such as protective walls/embankments to be made where they are essential. Bio-protection is by far most important. Quarrying for stones and soils to be strictly limited to specified localities which pose no threat of landslides.

Development to be limited to carrying capacity: Karwar with several major projects such as India’s largest naval base, Kaiga Atomic Plant, commercial port and a fisheries port, offices and several more establishments appears to be transgressing its ecological carrying capacity. The authors are presently engaged in a project estimating the ecological carrying capacity of Uttara Kannada district, and are expected to formulate specific measures for safeguarding ecological stability of the region as well as recommend developmental projects that are compatible with the rich biodiversity and ecological fragility of the region.