3.3.3 Surface Hydrology and Water Sheds
Hydrological networks are the spinal cord of the entire natural system. Rivers, streams, springs, aquifers, lakes, ponds and ground water are interlinked to each other, and though the links are not prominently seen they function in close association. If we discern the different determinants of natural systems, especially geology, climate and vegetation, these links will be revealed to us. Understanding these links and the functioning of these hydrological units is an important factor in planning and resource management. As was discussed earlier, water is the prime resource for any habitable place. The entire world has only 3% of its hydrological wealth as potable water, out of which major volumes are in the form of frozen ice, or as ground water. So it is very important for us to manage and protect the available water resources efficiently.
The Mao Chhu and its tributaries like the Setikhare Chhu, the Dhaula Chhu, Aipole Chhu comprise of the hydrological structure of the town. The river has its watershed higher in the mountains to the north of Sarpang Dzongkhag. The Gole Chhu, the Gong Chhu, and the Khar Chhu are some of the major tributaries of these rivers in its initial course apart from the small mountain tributaries and rivulets. These major streams are fed by their own network of numerous minor streams and rivulets through the gullies running down the hill slopes. These streams originate from natural springs, lakes and surface runoffs at higher altitudes.
Apart from these major rivers, there also exists a specific pattern of storm water drainage within the town. These are evident from the continuous strips of relief and the topographical character of the town. These features form a natural interconnected network of storm water drainage in the town. The past developmental activities of the town, like road construction have already disturbed this natural system to a major extent, and the result of which is also evident in the town with repeated flooding in some parts of the town every year. Another important issue that needs to be addressed is the man made surface hydrological systems which include the irrigation canals and catchment ponds. Very sadly, due to the recent limited use of these irrigation canals, they have now become carriers of sewerage from the town. These irrigation canals penetrating into the paddy fields provide potential opportunities for creating pedestrian connectors for the future development.
The river and streams support a variety of plant species within their Riparian Zone (the ecosystem in the immediate surrounding of the watercourse, which is influenced by it). In turn this eco-system protects the environment of streams and rivers.
3.3.4 Flood Prone Areas
Flooding in the terai region of Himalayas is one of the worst known calamities of the world. Gelephu, a part of this terai region is no exception to this phenomenon. The town has already shifted its location twice as a result of flooding in the Mao Chhu. Soil erosion in the higher hill slopes and the resultant siltation in the region is one of the main causes for flooding of rivers. Flooding in the region is a common phenomenon. As a result of these conditions the entire town is under threat of flooding, unless suitable measures towards flood protection are taken.
Click here for surface hydrology and watershed map
Click here for existing storm water drainage map
Click here for existing storm water drainage map1
Click here for flood prone and eco-fragile areas map
The entire planning process for the town assumes that essential flood control measures would be adopted towards protecting the town in the future. Since no scientific study is available, the flood prone zones of the town are identified by studying the past history of flooding and the topographical characteristics of the town. As a planning principle, zones with potential high risk of flooding should not be considered for intense urbanization. Very low density development with recreation oriented activities would be envisioned in these areas.
3.3.5 Eco-Fragile Areas
Development is inevitable and must be integrated within the existing eco-system. Uncontrolled growth is destructive. Conservation principles can avert destruction and can ensure enhancement of the town’s life and environment.
A study and analysis of various natural determinants regarding surface drainage, vegetation, fauna and avifauna reserves, flood prone areas, watershed regions, and physiographical character of the town has revealed various sensitive environmental zones of the town. By the process of overlaying all the maps and analyzing the related information, one can identify the natural resources and areas that need to be preserved during the future developmental processes. These constitute the eco-fragile areas of the town. The existing surface water channels are used as sewerage drains. River beds are either garbage disposal sites or are taken up for urban activities. Forest lands are cleared for urban areas.
The above identified places are creating a severe threat from uncontrolled growth. Flood protection, controlling soil erosion, and conserving surface water drainage channels within the town are some of the steps needed to be taken with immediate effect. These zones are truly the functional centers of the natural system. Suitable land uses for these zones are to be identified toward the conservation of these zones in the municipal limit.
3.4 VISUAL ASSETS
Physical Characters
Planning of towns will not be completed unless the process creates a spatial organization and provides a sense of orientation and enclosure in the development. Unless, like other settlements in the country, where the mountains and the terrains influence this process strongly by creating various metaphors of possible spatial organization, Gelephu because of its physiographic character leaves the planning process with minimal existing clues to achieve the goal. While, the western tradition of landscape architecture and urban design put its efforts into the creation of enclosed spaces and preserves of mankind, the Bhutanese tradition is to built upon and accentuate nature’s grand plan of things. Points in space take on more significance than deliberate attempts towards creation of enclosed spaces. It is nature that is supreme, not man.
The planning process for Gelephu should create a matching platform between these varied attitudes of designing of spaces for mankind. Understanding the existing physical characters of the town becomes crucially important for this reason and in the process of planning.
The physical character of the town is studied under three topics :
Physical Structure and Boundaries Demarcating Elements of the Town
The location of the town at the foot of the great Himalayas and the resulting visual dominance created by the mountains, provide a distinct visual character and spatial extent to the region. The mountains with lush green forest cover form a fitting backdrop for the town and acts as a dominant physical boundary demarcating the town. These mountains practically stop any visual (or) physical continuity beyond the ridge forming a natural enclosure for the town both in terms of physical character and visual perception. Apart form the mountain there are the rivers which cris-cross the plains creating micro water-shed boundaries within the natural landscape.
Visual Experiences in the Town Location
What makes the visual experience offered by a place interesting is the variety of visual possibilities and sequences it offers. Gelephu by virtue of its location offers two distinct visual experiences at any given point in the region. A restricted, enclosed vista created by the mountains towards the north and an open far-ending view line created by the open plains towards the south. These contrasting experiences, apart from creating a distinct character to the place, act as orientational and directional elements of the region. Certain key locations in the mountains, like the vista created along the Gelephu-Trongsa Highway towards the mountains and the view point at Fulahari, present an uninterrupted panoramic distant view of the town and its surroundings. These are significant as they locate the town with in the natural setting and represent the whole situation. The physical construct of the town and its underlying urban pattern form certain view lines and vistas. These get established both naturally and through designed directives. The Tsewang Goempa and the football ground work as a notional entrance gateway to the town, apart from imparting a visual character to the town. Certain sections of the town, particularly the Mao Chhu side, offer more spectacular views of the surrounding landscape and the vast extent of the river bed.
Visual Scale of the Town
The mountain ranges which can be seen from most parts of the town make the visual scale of the town comprehensible to a great extent. Nevertheless, the structure of the town with its linear streets, series of distinct visual corridors, the building masses and the open grounds generates a distinct set of visual scale to the town itself. Thus, the visual scale operates at two levels; the intermediate urban landscape and the “borrowed” distant landscape.