City prone to flash floods

Shillong’s urbanisation is not well-planned and this fact has been highlighted in several reports published in The Shillong Times. Now, an extensive report prepared by the USAID-GOI-UNDP, ‘Developing Resilient Cities through Risk Reduction in the Context of Disaster and Climate Change’, shows the precarious situation the city is in. Flood is among the various hazards studied and published by experts.
The study points out that the city is prone to flash floods due to high intensity of rainfall during monsoon. The water level in most of the streams flowing through the city tops the banks causing inundation of localities in the vicinity and this problem is aggravated by “a drastic reduction in channel capacities in most streams due to encroachments along their banks by buildings”.
“The city is drained mainly by the upstream reaches of Wah Umiam, Wah Umkhen and Wah Tamdong Rivers. Most of the drainage lines in the area are first, second and third order reaches of these rivers,” the report says, adding that drainage congestion in the Wah Umkhrah (Mc Cabe Road), Polo Market, Don Bosco Road, NH-40 Weiking Pdengshnong, Buddha Mandir Road, Veronica Road and Dhankheti Junction is the reason for flash floods.
The study observes that drains in many localities are clogged and rainwater simply flows onto the roads. The major findings of the assessment are:
1. Shillong does not have any major river flowing across the city. Only the upstream reaches of the first and second stream orders are originating from the city’s catchment areas. Therefore, the city does not get affected due to riverine flooding
2. The main cause of flooding in the city is heavy rainfall spells (see graph; numbers denote wards) and prolonged rainfall, which run for several days
3. Only the low stream order reaches originate in the city region and they have been clogged to dangerous levels. It multiplies the flooding problem in the city
4. The outskirts of the city are not affected due to flooding or flash flooding because of steep slopes of the river line. However, the inner part of the city gets flooded regularly
5. Several well-developed areas in the city are in the river floodplain areas. In some areas, the development has choked the natural flow of the river thus causing water logging and submergence of low-lying areas
6. In the Polo Market area, the riverbanks have been encroached very badly, which causes bank overtopping of floodwaters. Polo Ground is also in the flood plain of the nearby river line
7. Flood maps developed by the research team show significant water logging in the Polo Ground area
The assessment of the flood scenario in the city is intimidating and an alert for the government to act on war footing. The assessment will help authorities concerned plan remediation measures and save the city from a major disaster like massive landslides caused by constant flooding.

~ NM

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