What choking Bengaluru can learn from ancient Harappans

What excessive rains last week did to Bengaluru is not a problem specific to India’s tech capital. The national capital and the commercial capital of India too, like most cities of India, have been vulnerable to even normal downpours. In June, when it rained in Delhi, a photograph from 1970, showing a waterlogged Connaught Place, the central business district of the national capital, went viral on social media. medium94153896Mumbai presented a similar picture in early July, when many parts of the megalopolis were under the weather following a heavy downpour. medium94153953City floods during monsoon is a perennial problem of India, which is home to one of the earliest urban civilisations. The Harappa or the Indus Valley Civilisation was unparalleled in its urban makeup, and replicating its town plan is still considered a challenge to modern town planners.How our cities drain themselvesOne of the most outstanding features of the Harappan town planning — as excavations from the 1920s have shown — was its network of drains and sewers. The bath and kitchen waters or drainage from the latrines and the roof did not run into the streets or street drains directly. They were channelled through tightly brick-lined drains, emptying into the street drains.Each house had a drain to take out effluents. Each drain was connected to a lateral drain in each section of residential quarters. And lateral drains led the wastes to sewers, an elaborate network of which kept the Harappan cities clean, preventing water logging of the kind modern Indian cities face. medium94154551The larger drains had corbelled roofs and remained covered, running parallel to the main streets. For maintenance and inspection sump pits were made. Drains and sewer had stone, brick or wooden screens that stopped the solid wastes from being washed away with the water. These drains and sewers had removable bricks or dressed stones of varying sizes at regular intervals so that solid wastes could be removed to prevent blockade of the drainage channels. medium nocaption94157290The sewerage system had a gradient engineered to the desired direction of drainage. Sewers funnelled effluents on both sides of the roads and stayed below the road and housing levels to prevent spillovers and sewage backflow. The entire sewage network was lined by baked bricks or stones, stopping the dirty water from leaking. Drains and sewers were covered with stones, which could be removed in order to clean them.The authorities — not clearly known who they were as the Indus script is yet to be deciphered — ensured proper sanitation and urban hygiene for several centuries. The modern Indian cities stand in stark contrast to their ancient counterparts.Most Indian cities don’t have a sewerage that links individual housing units, residential complexes to the main sewer. This is surprising for the fact that sewage-treatment technology has tremendously improved since the Harappan days, when they drained their wastes into lands outside the habitation urban areas. medium nocaption941542421. How rain fury turned Bengaluru residents' lives hell2. CAG warned Bangalore on verge of collapse. Nobody listened 3. The problem with Bengaluru? NRN spelt it out in 2006 medium nocaption94154256The landscape questionGeology tells us that landscapes are principally fashioned by flowing water and wind. Increasing population and improving technology gave humans the ability to build their homes and workplaces in the paths of the flowing water and wind. Still a balance was found between the nature and human settlements, with excess water brought by monsoon in India finding their parking areas in swamps, forested lands and lakes. Water bodies tend to swell during monsoons. This also helps humans with their drinking water as the accumulated water in these pits — small and big — would allow seepage to boost the groundwater table, and help soil maintain its grip on the vegetation, thereby preventing desertification. But these lakes and swamps have been encroached upon by expanding human need and greed, supported by superior mechanical technology. For example, the Bruhat Bengaluru Mahanagara Palike (BBMP) released data last year saying that it is in charge of 204 lakes in Bengaluru and that over 180 of them were facing encroachments by the government or private entities. The BBMP classified 19 lakes as “disused”, meaning they are either barren or dry land (read, massively encroached upon). The story of encroachment, reducing the area of natural water bodies, is an essential feature of most Indian cities.Land grabA majority of the excavated Harappan cities was in the flood plains of the Hakra-Ghaggar river system. Some cities, such as Mohenjodaro, were rebuilt multiple times after every devastating flood. The new structures followed the same layout pattern as the old. There was practically no encroachment for about 400-500 years during what is called the mature phase of the Harappa Civilisation (2250-1750 BCE). medium94154177Choking of Bengaluru drains is linked to encroachment upon not only its lakes but also the improper maintenance of the storm water drains that criss-cross Bengaluru. These storm water drains are about a century old, decayed and now lack capacity. A rainfall of 5-10cm is enough to have the drains overflowing. Who is to blame? Drains have been reduced to dumpyards, with citizens discarding trash in them. Illegal constructions — residential and commercial — on the banks of storm water drains are ubiquitous, leaving no outlet for water. When it pours, water flows wherever it can. Encroachments allegedly happened with connivance of municipal officials. The city administration has also reportedly been slow in cleaning up the drains.The fact that the Harappans built their city structures over the same place for centuries — excavations at places like Mohenjodaro showed nine levels of rebuilding — suggests almost zero-encroachment upon the drains and sewers, and also the presence of manmade and natural water bodies. It also shows that the authorities carried out the municipal job with utmost seriousness. medium94157947In modern Indian cities, if their expansion devoured natural drains and lakes in Bengaluru and Hyderabad, and reclaimed a mega swamp to build its Mumbai mahanagar, the floodplains of Yamuna gave way to skyscrapers of Delhi-NCR. Water has no place to flow. And climate change is making the hydrological cycle — with rainfall as an essential part — erratic and unpredictable but with predictable impacts on humans.