The way our ancestors planned settlements and constructed buildings deserves careful study. They appear to have followed the principles of organic planning, placing buildings in accordance with the natural contours of hilly terrain
The Bhotekoshi flood of August 26 this year, nicknamed the "Himalayan Tsunami," has gone down in history as one of the worst disasters the country has suffered in recent times. More than 1,500 people perished in this disaster, with several others still missing. The human toll reached such staggering heights because many people ignored the early warnings. The Himalayan Tsunami was followed by yet another devastating flood in the Budhi Gandaki River on October 11. Fortunately, no lives were lost in the latter disaster because of the prompt response to the early warning issued by the government.
What caused these catastrophes? Interestingly, the two events were similar in nature. In the case of the Bhotekoshi flood, a large mass of rock broke away from its parent rock on the northern flank of Langtang Himal. The mass was so enormous that its movement triggered an earthquake measuring 5.2 on the Richter scale. It struck the Lhinde River with such tremendous force that an incredible amount of heat was generated in the process. As a result, ice melted, and the resulting water, mixed with debris as it flowed downstream, gave rise to the Himalayan Tsunami.
A study conducted by the National Disaster Risk Reduction and Management Authority (NDRRMA) revealed that a similar mass of rock broke away at an altitude of 5,500 metres upstream of the Udling River, which flows between the Shyra and Chamara snow-covered mountains. The event occurred at 4:20 a.m. on October 11, triggering an earthquake of magnitude 3.5. The resulting mass struck the confluence of the Udling and Shyar rivers, generating a massive debris-laden flood that rushed downstream at high velocity, engulfing everything in its path.
The striking similarity between these two events lies in the detachment of enormous masses of rock from adjoining mountain formations, triggering earthquakes. Our Himalayan mountains consist of ice, rock, and soil. As temperatures rise, ice melts due to a phenomenon associated with the thawing of permafrost. Consequently, portions of mountain slopes may become unstable and break away, resulting in massive landslides that rush downstream at incredible speeds. Such events are likely to become more frequent in the future, as evidenced by the occurrence of the Thame, Bhotekoshi, and Budhi Gandaki floods in quick succession.
The NDRRMA recently declared that the rescue phases of both the Bhotekoshi and Budhi Gandaki flood disasters had come to an end. It is now engaged in reconstruction. This reconstruction, however, must depart from conventional practices and adopt climate-resilient planning and building methods. Climate-resilient planning and construction must demonstrate a high degree of sensitivity to changing climatic conditions.
There are historical examples of cities adopting new approaches to planning and construction following disasters. One such example is the Great Fire of Rome, which occurred in the first century CE during the reign of Emperor Nero. Following the fire, Nero not only widened the streets but also replaced timber with stone and marble in construction. Subsequently, Rome was said to have risen from ashes and been transformed into a city of marble.
Similarly, roads were widened and timber was replaced with stone in the aftermath of the Great Fire of London in 1666. In Nepal, too, following the earthquake of 1934, New Road underwent a transformation, with wider roads and buildings featuring a uniform façade.
Indigenous knowledge can make a significant contribution in such circumstances. The way our ancestors planned settlements and constructed buildings deserves careful study. They appear to have followed the principles of organic planning, placing buildings in accordance with the natural contours of hilly terrain. Since Nepal's hilly countryside is characterised by small terraces and steep slopes, people constructed small buildings suited to the limited size of the terraces.
They did not adopt orthogonal or grid-based planning, as seen in Chandigarh, India, or Tikapur in Nepal. Nor did they imitate the diagrammatic planning of Rajbiraj, which was laid out according to the Prastara form by Dilli Jung Thapa after he observed Jaipur, the Pink City of India. They also avoided grand planning, commonly known as Baroque planning, elements of which were incorporated into the design of Rana palaces such as Singha Durbar. Chautaras served as landmarks, while pathways played a dominant role in shaping settlements. Junctions were often marked by temples. Distinct districts, in the modern urban-planning sense, were largely absent, as the steep terrain offered little scope for such elaborate planning.
In building construction, traditional builders used climate-resilient materials such as stone for foundations, walls, and roofs. Timber was used for floor joists and binders. These materials required relatively little industrial processing and, in their traditional forms, had a low carbon footprint.
Climate-resilient construction techniques have also been practised in the Tarai since time immemorial. However, these traditional technologies must be scientifically evaluated and adopted only if they meet appropriate safety and performance standards. Two such technologies used in the Tarai are bamboo-reinforced walls and bamboo-grid floors. The former have been used in residential buildings, while the latter have been used in the construction of raised platforms for performances at fairs.
A laboratory test of bamboo-reinforced laterite soil reportedly showed that its strength was comparable to that of brickwork constructed using a cement-to-sand ratio of 1:4. This is significantly better than the prevailing practice of using brickwork with a cement-to-sand ratio of 1:6.
Load testing also showed that a bamboo-grid floor could withstand the live, dead, and dynamic loads encountered in residential buildings. Roofs could likewise be constructed using a bamboo-grid framework covered with plastic sheeting of the type used in tunnel farming. Such sheeting could last for nearly 60 years, provided it is used solely as a covering material and is not required to bear structural loads.
This construction method offers potential advantages over conventional residential building technologies. Moreover, it is relatively inexpensive, an essential consideration in post-disaster situations where financial resources are limited. Another significant advantage of this technology is its potential to withstand earthquakes.