Tuesday, December 13, 2011

Use of Engineering and Environmental Geological Maps in Infrastructure Development Planning of Fast Growing Cities in Nepal


Krishna P. Kaphle1 , Lila N. Rimal2 and Dinesh Nepali2
1 Majurmarg-60 Panipokhari, Maharajgunj, Kathmandu, Nepal, e-mail: kkaphle@hotmail.com
2 Department of Mines and Geology, Lainchaur, KathmanduNepal

Abstract

Influx of people from the villages to the cities to look for the jobs, education, business, health care etc. are the main causes of fast growing and haphazard expansion of cities in Nepal. Rapid population growth, uncontrolled urbanization, haphazard development of infrastructures and their poor management and unsystematic exploitation of natural resources are the major causes of natural and human induced disasters and environmental degradation in urban areas. Scarcity of treated water for drinking and poor sanitation resulted frequent outbreak of communicable diseases that endangering public health. Construction of non-engineered houses and use of low quality construction materials without following the National Building Code are the major causes of collapse of residential buildings even in the earthquake tremor of low intensity.
                                                          
Department of Mines and Geology has already prepared Engineering and Environmental Geological Maps (1:50,000/ 1:25,000 scale) of fast growing cities like Katmandu, Pokhara, Butwal, Hetauda, Dharan, Biratnagar, Bhairahawa, Lumbini and Birendranagar with a view to provide basic geo-scientific information required for urban planning, infrastructure development planning, land use planning, environment protection and disaster mitigation. These maps furnishes data on geology, topography, land use pattern, settlement and industrial areas, natural resources, infrastructures, water sources,  sanitary landfill sites, natural heritage etc. Areas endangered by natural hazards are marked by standard symbols and the risk for human lives, properties and infrastructures are identified and categorized as high, medium and low hazard/ risk. All geologically related environmental issues are identified.
                                                                                                                                                                                                               
The engineers, planners, decision makers and donors who are involved in infrastructure development works, disaster management and environment improvement projects can integrate available geo-scientific information and make multiple use of these maps to locate geologically safe ground and environmentally sound areas for new settlement, selection of suitable waste disposal site, industrial area development and also look for construction material required for development works in urban areas to minimize the risk of hazard and protect the natural environment.

Introduction

Department of Mines and Geology (DMG) has started to prepare Engineering and Environmental Geological Maps of major and fast growing cities under the Nepal/ German Technical Cooperation since 1986. It has published first such map of Kathmandu Valley and Pokhara Valley (scale 1:50,000) in 1988 and circulated to the potential users after organizing workshops. These maps became very popular among planning engineers and structural engineers especially in Pokhara Sub-Metropolitan City, Pokhara Valley Town Development Committee and Department of Housing and Urban Development etc. In the workshop engineers found the map a bit complicated to read because of more geoscientific information in it. By understanding their difficulties a simplified Environmental Geological Map of Kathmandu and Pokhara are also prepared and supplied to them. DMG continued such works and published similar maps of Butwal area (scale 1:25,000) and Dharan area (scale 1:25,000). Four such maps of Hetauda, Bhairahawa - Lumbini, Biratnagar and Birendranagar (Surkhet) are in the process of publication. Preparation and regular publication of such maps of other fast growing cities are in progress since the demands of such maps are high from different government organizations involved in infrastructure development works, municipalities, town development organizations, housing companies, donors, Engineering institutes etc.

The prime objective to prepare Engineering and Environmental Geological map of fast growing cities was to provide basic as well as specific information on ground stability condition of the soils/ sediments/ rocks present in the area and explain their engineering properties and provide geoscientific information required for a better land use and urban development planning and infrastructure development planning; identify hazardous/ risk areas and recommend precautionary measures; identify various types of natural resources available in the area and geological sites of natural heritage; locate drinking water sources, recharge areas and their quality; identify all types of pollutants responsible for water, air and ground pollution; and recommend suitable measures for environment protection
The methodology applied to prepare such maps is literature review at the initial stage that includes review of existing reports, maps, research papers and collection of existing data on geology, geomorphology, hydrogeology, engineering geology, seismicity, hazards and environmental studies. Aerial Photos and Landsat Images are interpreted and additional information has been incorporated in the maps. It is followed by field visits/ ground survey, geological and hydrogeological investigations and checking all types of sediments/ soils and the rock types and their engineering properties. SPT and Grain size analysis were performed to supplement the existing data. All these data are transformed into digital database using GIS in ARC/INFO format and processed using Window driven ArcView software. Cartographic works are done with the help of FreeHand program. Maps are produced in multicolor line works using special plotter. Legends and indexes are prepared in a format that is easily understandable even by non-geologist. GIS with ARC/INFO is applied for all types of data storage, data processing and plotting of the coloured map. All such GIS data layers are documented in standardized form and preserved. In the map the colours for different geological units are selected according to the standard international practice as practicable. The colours together with letter symbols are applied for each lithological unit to make easy to readers. Similarly standard graphic symbols and patterns are expressed in the map as far as possible and practicable. Topographic contour lines, drainage patterns and all other features are taken from existing digital data of topographic maps (Toposheets at 1:25,000/ 1:50,000 scale). Rivers, lakes, roads, foot tracks, height points, historical monuments, cultural heritage, settlements, hospitals, open grounds, etc. are indicated by standard symbols.

General Geology

In most cases bedrocks are exposed mainly in the hillocks, river cut sections and hill slopes around the valley. The valley is filled with the fluvio-lacustrine sediments (in Kathmandu), Glacio-fluvial deposits (in Pokhara), as river fan deposits (in Dharan and Butwal) and fluvial deposits (in Bhairahawa, Lumbini and Biratnagar) of Quaternary age. The thickness of the valley fill sediments varies considerably (e.g. in Kathmandu from 78m to 549m, and in Bhairahawa >1000m). General geology, geological structures, rock and soil types are identified, their engineering properties are described briefly in the legend of the map (Fig.1). Some active faults and thrusts identified in the field are drawn on the map. Geological units/ formations like unconsolidated loose sediments (e.g. alluvial, colluvial and residual soils) and consolidated sediments like young sedimentary deposits/ Formations and different types of bed rocks are identified and named on the basis of their mineral content, grain size, texture, structure and genesis. All geological units are separated from each other by standard colours, line patterns and letter symbols. Field survey also enabled to map the old and recent landslides and delineate the areas of potential instabilities on the hill slopes that endangered the area. Geological traverses covered the hill slopes, mountains, and the valley floor areas to furnish information on geology.

Engineering and Environmental Geological Map

The Engineering and Environmental Geological Map (an example Fig.1) include information/ data on geology (ground condition, soil/ rock types), topography, slope, land use pattern, existing and proposed settlement areas, industrial areas, natural resources, infrastructures like existing road networks, airport, water sources, water quality, waste disposal sites/ sanitary landfill sites etc. However, detail studies specific to the site, structure and land use is essential prior to make the final decision. Areas endangered and affected by natural hazards with risk for human life, properties and infrastructures are identified and categorized as high, medium and low hazard/ risk. Natural resources like minerals, water, forests are identified. Natural heritage and geologically related environmental issues are also identified. Areas prone to various geo-hazards like landslides, land subsidence, sinkhole, block falls, gully erosion, and flood are marked by standard symbols and hatched lines.

Urban settlement areas and industrial areas are shown by inclined double cross hatching and straight double cross hatching respectively on the map (Fig.1). Cultural heritage and historical monuments like Temples, Stupas, Old Palace Complexes (Durbar square) etc. are shown by appropriate symbols. The legend of the map contains detailed explanation of various map elements related to engineering and environment geology, the techniques applied to express the map elements and the engineering geological properties of the rocks and the soil. At the same time the information on individual geological units and their lithological characteristics are described (Fig.1), and in the next column their

    Fig.1: Engineering and Environmental Geological map of Dharan Area (published by DMG in 2009).

geotechnical properties are presented. The legend also helps to the map readers and users in interpreting and deriving the various types of information. However, the map and the information contained there in cannot replace the detail site investigation procedure that is essential for the specific purpose of infrastructure design and construction.

Geological Hazards and Related Environmental Problems

The areas susceptible to different types of hazards and risks are identified on the map. Geologically hazardous areas and type of hazards are indicated by standard symbols. The degree of risk/ hazard is directly related to geology, sediment composition, degree of compaction and cementing material, engineering properties of the rock/ soil, topography, slope, climatic condition etc. Risk and hazard pertinent to the hill slopes due to landslide, rock fall, and gully erosion are indicated in the map. Similarly the areas susceptible to different degree of liquefaction hazard and the areas prone to flood hazard, low bearing capacity and different categories of subsidence hazards are also delineated. Common geological hazards related to infrastructure development and environment are identified and briefly described. Low bearing capacity areas are susceptible to land subsidence and differential subsidence due to the presence of saturated sediments like lacustrine soft clay, silty clay, black clay and peat. Soil tests (SPT and grain size analysis) are performed to identify the low bearing capacity areas. Among them Kalimati Formation and peat of Lukundole Formation (in Kathmandu) are vulnerable to subsidence. In the map these areas are shown in inclined red lines (hatchings). Over extraction of ground water in Kathmandu has also made some area susceptible to ground subsidence. Heavy construction works in such ground requires detail investigation of the ground and special foundations like strip or mat or pile foundations require for specific type of building construction.

Almost all the low lands by the sides of the rivers are prone to flood hazards. It is common in Terai Plain and some parts of mid valleys and dune valleys. Due to blockage of natural flow of river water some parts of western Terai frequently get flooded during monsoon season. Flood and landslide of 1993 in central Nepal damaged 3 highway concrete bridges, Kulekhani hydroelectricity plant, Bagmati irrigation dam and cannels, different parts of Tribhvan Highway, and 1170 people lost their lives. People of Kathmandu and Hetauda were also affected by this disaster. In the map river flood plain areas are shown by symbols/ hatchings. The land of such category is not suitable for settlement and construction of heavy structures. However, such areas can be used for dry and wet cultivation, green belts, development of open spaces for recreation etc. Such area could be potential for ground water.
                                               
Landslide and flood hazards are the common geogenic hazard in Nepal. Quite a few small as well as large active and dormant landslides are recorded on the hill slope. Deforestation and improper land use like cultivation on high angle hill slope, haphazard construction of roads and exploitation of natural resources are the root causes of gully erosion and landslides. Landslide has affected the northern parts of Butwal, Hetauda, Dharan, Pokhara and Birendranagar where as bank collapse and flood hazards are common in Pokhara, Butwal, Biratnagar, Bhairahawa and Lumbini. Cloudburst and subsequent floods and landslides had destroyed many houses and highway concrete bridge over Tinau River (Butwal) in 1981, and totally damaged 37 houses at Butwal in 1998 (Fig.2). In the map active and dormant landslides and areas susceptible to rock fall are delineated. Standard symbols of red lines works are used to delineate such areas.












Fig.2: Srawandanda Landslide Disaster destroyed 37 houses in Jyotinagar, Butwal (1998)             
                                                                                                                                                                                                                          








3(a) Before 1934 Earthquake      





                                                                                                                                                               
                                                                                                                                                        3(b) After 1934 Earthquake



   






Fig.3: Bhaktapur Durbar Square damaged by 1934 Great Earthquake
The earthquake catalogue of Nepal shows that several earthquake events greater than 5 Richter scale occurred in different parts of the country (Kaphle and Joshi 1998). Out of these the largest one (8.3 Richter scale) was of 1934 (Fig.3), which inflicted heavy damage and loss of lives in Kathmandu valley.

Because of location of Nepal in the central part of the seismically active Himalayan belt almost all parts of Nepal is susceptible to earthquake. Recent study (UNDP/BCPR, 2004) ranked Nepal the 11th among the 200 countries in terms of earthquake risk and 30th in terms of flood risk. Kathmandu is ranked as one of the world's most vulnerable cities for an earthquake disaster (JICA, 2002). Almost all the fast growing cities are located by the side of rivers on the valley fill sediments or on alluvial fan deposits which are loose and saturated with water as a result the chances of liquefaction during earthquake are very high. The Kathmandu Valley Earthquake Risk Management Project (KVERMP, 1999) has predicted that an Earthquake similar to that of 1934 would cause 40,000 deaths and 95,000 serious injuries and almost 60% of the infrastructures will either be damaged (40%) or destroyed (20%). Butwal, Dharan, Hetauda, Bharatpur, Birendranagar, all are very near to Main Boundary Thrust (MBT) and Butwal and Dharan (Fig.1) are also close to Main Frontal Thrust (MFT). Both thrusts (Fig1) are still active, that is why the chances of EQ disaster are very high in these cities. Therefore, buildings and other major constructions in all these fast growing cities must strictly follow the National Building Code of Nepal (BCDP, 1994) and national EIA guidelines in order to take into design consideration.

Sinkholes and land subsidence hazard are common in almost all types of calcareous valley fill sediments in Pokhara Sub-Metropolitan City. Among them Ghachok Formation is found to be the most vulnerable. The area west of Seti River in old Pokhara bazaar, north-east of Phewa Dam, David fall and Gupteshor area, and Hengja Bensi area are more vulnerable to sinkholes. Large sinkholes as wide as 35m in diameter and caverns/ caves of over 1km long are reported in Pokhara. Karstifican are commonly seen in Mahendra and Chamere cave (Gupha) area. Bank collapse and Block falls are more frequent along the course of Seti River (Fig.4) and its tributary streams. Pinnacles are also recorded at many places.

                










Fig.4: Damaged Highway Bridge over Seti River, Pokhara due to River bank collapse                                          




























































Fig.5: River Bank Scouring and damage of   Protection walls in Tinau River, Butwal      
                                                                              
Siltation and eutrophism is highly affected the Phewa Lake in Pokhara. Almost half part of the beautiful lake has been filled up by the debris/ sediment derived from the uphill side due to gulley erosion and landslide and reduced its size considerably. Phewa Lake, Seti River and its tributary in the city area are polluted by direct connection of sewerage drains. Problem of eutrophism is mainly due to fecal contamination. Similarly huge amount of sediments derived from the up hill in Tinau Khola at Butwal and Seute and Sardu Khola at Dharan and Samri Khola and Rapti Khola in Hetauda caused huge amounts of sediment deposit that causes frequent change of river course during flooding that affected the settlements and infrastructures like bridges (foundation scouring) and protection wall/ spur (Fig.5) etc. by  river bank scouring/ cutting.   

Natural Resources                                

Natural resources like Minerals, Water and Forest are specially dealt with during mapping. All the existing mineral resources such as mines/ quarries of construction materials (limestone, marble, diatomite, lignite, block stone, building stones etc.) and river gravels (boulders, gravel, sand, silt, clay) are shown by standard cross hammer symbol in combination with one or two letter acronyms indicating the different commodities. Haphazard mining and over extraction of sediments in the river course has resulted river bank collapse and flooding during monsoon and improper location of stone crushing plants are deteriorating the environment. Sources of surface water (e.g. rivers/ streams/ lakes/ ponds, springs) and ground water are marked by standard symbols on the map and their quality determined after chemical analysis are presented in the report. In many cases river and lake water are contaminated once they inter into the city area due to direct connection of sewerage drains and dumping of all types of waste material in the river beds. Rivers of Kathmandu are highly polluted and water is not usable for household uses at all. Forests are the areas for soil and water conservation and they are delineated in the map by green horizontal hatchings or by typical symbols occasionally with boundaries. Deforestation by human encroachment is the common problem in almost all the near by settlement areas. Therefore, restriction is imposed to cut the trees for wood to construct houses, fodder, firewood etc. Once reforestation campaign is lunched and the existing forests are converted to community forest deforestation activities are fairly controlled in Nepal.
                                                                  
Use of Engineering and Environmental Geological Map in Infrastructure Development Planning and Its Limitation

The Engineering and Environmental Geological map provides basic guidelines and deliver the primary geoscientific information that are important and useful to the planners, engineers, decision makers, managers, lecturers of Engineering and Geotechnical Institutions, and other user.  It serves as an important database required for regional and urban planning, infrastructure development planning, structural design, land use planning, disaster management, environment protection, identification of sites for construction materials and drinking water sources. However, detail studies specific to the structure and land use is essential prior to make the final decision. It is also useful for obtaining the general information about the present status of the land use pattern, general classification of the ground condition for all types of civil constructions, potential areas for natural resources, waste disposal sites, environmentally degraded and hazardous land and other areas requiring protection measures.

The planners, decision makers, engineers involved in infrastructure development works, environment improvement project workers and disaster management specialists can make multiple use of these maps especially to locate geologically safe ground and environmentally sound areas for new settlement, industrial area development, sanitary landfill site, sewage treatment plant, recreation centers and public parks, cultivated land, and also look for construction materials required for development activities.

It is a reconnaissance type map which is prepared at regional scale (1: 50, 000 or 1:25,000) with a view to give regional picture. As a result, it has some limitation as specific details such as bearing capacity of the soil (sediments) of the particular site, geological age of individual units and location of all active faults etc. could not be included at this stage. Regular upgrading of the map with additional information and printing of revised version (new edition) is necessary.

Most of the low lands are suitable for paddy and sloping dry lands for wheat, maize, millet crops, fruit farms, tea garden, reserved forest etc. Agricultural/ cultivated lands are not delineated in the map. Protected forest areas are well demarcated with symbols and boundary lines. Except temporary sites existing, abandonment and proposed sanitary landfill/ waste disposal sites are shown in the map by standard symbols. Only low permeable areas such as fine grained silty clay, clayey silt and peat bed and old clay mine burrows are suitable sites for waste disposal. Detail site investigation specific to waste disposal is required for final selection.

Open spaces like public parks, playing grounds and recreation centers are very important places for relief operation in case of any natural calamities like earthquake, flood and other emergency situations. Therefore, due importance is given to such areas and delineated in the map. Location of general utility service stations for electricity, water supply, ropeways, road networks, airport, fuel storage sites, hospitals, police stations, army camps etc. are marked in the map so that one can easily located the place to get services. Cultural heritage and historical monuments like Temples, Stupas, Durbar square complexes etc. are shown by appropriate symbols.
                                                                                                                    
Geo-Environment and Pollution

Improper locations of some industries like cement factory in Hetauda; brick kilns, stone crushing plant and stone quarries in Kathmandu valley; stone crushing plants in Butwal and along the road sides; carpet, garment, leather factories (Fig.6) and chemical industries within the core city area are the main sources of air, water and ground pollution. Similarly discharge of municipal waste, industrial effluents and toxic chemicals directly into the river, and haphazard dumping of solid waste by the side of the river/ flood plain (Fig.7), direct connection of sewerage drains to the rivers etc. have created river water pollution in most of the cities in Nepal. Air pollution is increasing from the smoke and dust from the chimneys of the brick kiln and others, exhausted fumes from poor conditioned vehicles, use of adulterated fuels etc. All these types of pollution directly or indirectly are creating health hazard problems to the people in fast growing cities. Most of the existing industrial areas are marked in the map.

 
Fig.6: Industrial effluents from leather factory,         Fig.7: Haphazard dumping of Municipal waste in
          a source of Pollution in Biratnagar                                      Bagmati Riverbed, at Kathmandu
                                                                                                       
9. Conclusion and Recommendation

The Engineering and Environmental geological Maps of fast growing cities in Nepal can be considered as a useful map for cost effective and efficient urban development planning. It is a good base for Regional planning, Town/ urban development planning, infrastructure development planning, land use planning, site identification for new settlement areas, selection of industrial areas, landfill sites, sewerage treatment plants, recreation parks, hospitals, educational institutions, fuel storage sites etc. It is also useful for site location for construction materials, drinking water source, reserve forest etc.
                                       
The map also provides the basic information on the soil/ rock types, their engineering geological properties, ground condition and it can be used for preliminary planning of foundation type for different constructions/ structures. It also depicts the hazardous areas such as landslides, flood, sinkholes and land subsidence prone areas, low bearing capacity areas etc. that makes aware of Planners, Engineers and others to plan and design the structures.

It is recommended to integrate all available geoscientific information and make multiple uses for the development activities in the fast developing urban areas to minimize the risk of hazard and protect the natural environment. Specific types of foundations for civil construction in different types of sediments/ soil are also recommended.

The Government/ Municipalities must enforce the National Building Code of Nepal (BCDP, 1994) and strictly follow the national EIA guidelines in all types of construction and other development works in the city areas. It is a part of pre-disaster preparedness. 

Natural resources, Historical monuments and Cultural heritage are the important wealth of the country and valuable culture must be protected from the environmental degradation.

All the industries and industrial areas/ industries, brick kiln, stone crushing plants which are located in core city or close to the settlements must be shifted far away from the city area and waste disposal sites near the airport must be closed to avoid pollution and possible birds strike problems.






Acknowledgement

The authors are grateful to Mr. S.P. Mahato, Acting Director General, DMG for giving permission to get all the related information and necessary reference materials from DMG library to prepare the paper. The authors wish to acknowledge Ms. Afia Akhtar, Convener, International Conference on Geoscience for Global Development (GeoDev) and Director General, Geological Survey of Bangladesh, and all the Members of the Organizing Committee for providing free Registration (accommodation and local transport) to participate in the Conference; and Nepal Academy of Science and Technology (NAST) for providing partial fund to Mr. Kaphle for his international Travel (Kathmandu - Dhaka - Kathmandu) to attend the Conference and present this paper.  

References

BCDP (1994): Nepal National Building Code and Seismic Hazard Mapping and Risk Assessment for Nepal. UNDP/       UNCHs (Habitat) Subproject; NEP/88/054/21.03- Ministry of Housing and Physical Planning, HMG, Nepal;                                   prepared by BWI, SILT, and TEAC, Golder Associates, URR, Kathmandu.
DMG (1998); Engineering and Environmental Geological maps of Kathmandu Valley, and Pokhara Valley. Published     by DMG Nepal in cooperation with BGR, Germany.
DMG (2008), Engineering and Environmental Geological Map of Butwal Area; Published by DMG.
DMG (2009) Engineering and Environmental Geological Map of Dharan Area; Published by DMG.
Japan International Co-operation Agency (JICA, 2002); the study on earthquake disaster mitigation in the Kathmandu                valley, Kingdom of Nepal. Final report vol. I, II, III, and IV, JICA and Ministry of Home Affairs, HMG           Nepal, unpublished report.
Kaphle, K.P. and Joshi, P.R. (1998), Report on Engineering and Environmental Geological Map of Kathmandu Valley; DMG unpub. report. 38p.
Kaphle, K.P. and Koiral, A. (1998), Report on Engineering and Environmental Geological Map of Pokhara Valley.          DMG unpub. report, 20pp.
Kaphle, K.P. and Jnawali, B.M (2002) Environmental Geological Assessment of Butwal Municipality Area and its         Surroundings, Western Nepal; Proceedings of 4th South Asia Geological Congress (GEOSAS-VI), pp417-                428.
Kaphle, K.P. (1998) Report on Environmental Geological Assessment of new infrastructure development in Pokhara     Valley. DMG Unpub. report 43p.
Kaphle, K.P. and Nakarmi, M. (1997): Comprehensive Database (Basic Information) on Disaster Management                Capabilities in Nepal. Report submitted to UNDP/ Nepal, Disaster Management           Secretariat, Unpub. report,                 59p with 11 figures, 16 tables, 104 appendices and 11 attachments.
KVERMP, (1999), The Kathmandu Valley Earthquake Risk Management Action Plan; A product of Kathmandu             Valley     Earthquake Risk Management Project implemented by NSET-Nepal and Geohazard International,           USA (GHI), 37p. unpublished report.
UNDP/ BCPR (2004), Reducing disaster risk: a challenge for development; A global report of UNDP, 146p.
WDR (World Disaster Report - 2005), International Federation of Red Cross and Red Crescent Societies, 251p.

Figure Caption

Fig.1: Engineering and Environmental Geological map of Dharan Municipality Area

Fig.2: Srawandada Landslide Disaster destroyed 37 houses in Jyotinagar, Butwal (1998)

Fig.3: Bhaktapur Durbar Square damaged by 1934 Great Earthquake

Fig.4: Damaged Highway Bridge over Seti River, Pokhara due to River bank collapse

Fig.5: River bank scouring and damage of protection walls in Tinau River, Butwal

Fig.6: Industrial effluents from leather factory, a source of Pollution in Biratnagar          

Fig.7: Haphazard dumping of Municipal waste in Bagmati Riverbed at Kathmandu

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