Solving the perennial flooding crisis of Bihar

Solving the perennial flooding crisis of Bihar

Background: Floods annually displace lakhs of people in not only Bihar but other states as well, depriving them of their livelihoods and the need for relief and rehabilitation. Billions of funds from NGOs, Bill and Melinda Gates Foundations, NGOs, corporates helping through CSR funds have helped alleviate the pains of the displaced but the root cause still remains to be resolved.

The challenge is to channelize the floodwaters for irrigation, canalization, prevent harvests from getting deluged, utilize the rich alluvial deposits brought by the rivers.

Bihar has several rivers running through it from Nepal and UP, such as Ganga, Sone, Punpun, Falgu, Karmanasa, Durgavati, Kosi, Gandak and the Ghaghara, to name a few. Nearly 85% of the state’s land is under cultivation. National Water Development Authority (NWDA) under the water resources ministry has prepared the DPR for interlinking of rivers for Bihar government with an outlay of Rs 4,214 crore is needed for construction of channels, embankments, and other infrastructure. Water being a state subject, the center cannot intervene directly. There needs to be a synergy between the state of Bihar, intervention from the central government to chalk out an action plan with the Nepalese government.

Overall, improved flood preparedness and community participation; flood hazard mitigation; and integrated flood management system is the need of the hour. Specifically, Bihar needs to connect eight rivers,  the Kosi-Mechi link will be the first project. The Kosi will be connected with the Mahananda through a 120 km-long canal. This link is considered crucial to controlling floods in the state. Kosi, in the past few decades, has inundated scores of villages in the region. This link will make Bihar’s worst flood-prone districts, Kishanganj, Supaul, Purnia and Araria safe.

Bright spot: Rich alluvium brought by the rivers increases soil fertility and can be used for post-monsoon sowing as well as in Rabi season. The silt and sediments can be used in other industries as well. 

Story-boarding: Before-and-after storyboards scenarios are shown below:

While creating embankments, levees, dams tinker with the natural flow of these rivers and wreaks havoc, all of these are highly cost-intensive measure. 

Hypothesis: Community participation in desilting and dredging the river beds and alluvial deposits after floodwater recedes

Dredging and desiltation will allow more water to stay in the river and it makes the river navigable for larger vessels. Although dredging along an entire river basin may seem like a humungous task, but people will be motivated to contribute with “Shram Daan”, when their homes, livelihoods are dependent on it. Besides, it frees them from the perpetual cycle of displacement and rehabilitation.

The bright spot during this flooding post-session is the rich alluvium, with high quantities of potassium, nitrogen and phosphorus, which is brought into the lower riparian state area with the floodwaters and deposited here. The Kosi river has an exceptionally high sediment yield of 0.43 million tines/year/km2 which is accommodated in a very narrow alluvial plains almost one-fifth of the upland area. 1,082 million tonnes of sediments have deposited in the last 54 years, i.e. 408 million cubic metres in terms of volume at a rate of 5.33 cm per year. As per the research of Central Glass and Ceramics Research Institute (CGCRI)  “ “The Kosi silt consists of fine to very fine sand and is dominated by quartz and significant amounts of muscovite mica. Chemically, this is composed of 72-76% of silica followed by aluminium oxide (10-11%), iron oxide (3-4%), potassium oxide, sodium oxide (3-4%), calcium oxide, magnesium oxide (< 2 %) and minor amount of titanium oxide(<1%),” the study says.

Lack of this NPK in the soil elsewhere leads to overuse of chemical fertilizers which further leaches into the groundwater. Mobile soil health testing labs are useful in determining the proportion of these nutrients and controlling their usage.

Desiltation and dredging this alluvium from the river basin can be done with community participation, employing MNREGA workers and incentivizing them. 34 such critical points or hotspots have been identified along the course of the Kosi river. In the past, desiltation has not worked because it was dumped somewhere nearby which again flows back to the river in the next monsoon season.

Looks-like Prototype:

Low-cost solution- 1-day field trip to one of the hotspot regions in the flood-prone district, once the flood water recedes. Sensitize people, show them the richness of the soil using mobile soil testing kits from the gram panchayat. Along with Gram Sarpanch and MNREGA workers, show them the efficacy of desilting process and collection. Informing them of the commercial use of dredged material as raw material to several industries. This would also add to their sources of income and if carried out on a war footing could save their village from the clutches of floodwaters.

Cost of the experiment- time and effort involved in convincing the local government authorities and sourcing the mobile sampling unit from them, Rs 3500 cost of hiring a tractor.

Measures of success

·       Convince local and MNREGA officials to allow for a 1-day trial

·       Convince even 30 villagers to actively sign up in this desiltation process for 100 days of guaranteed MNREGA work.

·       Desilt 100 kilotons of sediment and hire a tractor to transport it

·       Demonstrate the quality of the tested nutrient-rich soil features to some local and MNREGA officials, industries as well as to the villagers

It’s a low-cost solution which converges on various schemes of government of India, such as free soil testing, MNREGA work for the creation of durable assets and utilizing the local governance machinery in-situ. It easily replicable to other critical hotspots along the meandering river and if the process of desiltation and dredging is carried out continuously for the remainder of 8-9 months prior to next monsoons setting in, this perpetual the problem could be solved to a certain extent.

Long term solution- A supply chain network can be established in long-term with the railways as well as inland waterways to transport this silt and sediments dredged to various industries. This highly enriched silt is used as backfill material in roadways construction, in brick kilns for construction of buildings and as a raw material for the portland cement industry. The dredged river bed allows vessels with a larger draft to traverse these inland waterways. The topsoil could also be transported to places to rejuvenate poor agricultural soils and the organic content could also increase soil productivity.

References:-

1. Bihar flood management information system, Status report, 2008.
2.  World Bank Report: Bihar Kosi Basin Development project
3. Earth Science info
4. https://www.manthan-india.org/wp-content/uploads/2018/07/Kosi-and-Gandak-Report-min.pdf
5. 'Scoping Study of Siltation in Kosi river of Bihar' conducted at the behest of the Bihar government supported by the UK Department of International Development’s Action on Climate Today.
6. https://www.indiawaterportal.org/articles/map-showing-site-where-river-bagmati-breached-its-embankments-sitamarhi-bihar-2009
7. http://fmis.bih.nic.in/Basin1_july09/basin.html
8. https://soilhealth.dac.gov.in/