Report on Scoping Study to Manage Silt of Kosi River, Bihar
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2018 Sediment Management in River Kosi – A Commercial Perspective Submitted to Submitted By BASIX Consulting and Technology Services Ltd., Hyderabad Sediment Management in River Kosi – A Commercial Perspective 2018 Executive Summary The Kosi is known as “sorrow of Bihar” due to its frequent and devastating floods in Bihar. The river carries very high annual sedimentation load (multilayer staking of silt). It was estimated that rate of sedimentation is 5.33 cm/year in Chatra-Birpur and 2.83 in birpur-Baltara. Over 10 million people are hit by water logging even if the rainfall in the state is normal or deficient. Removing deposited silt and managing it for commercial purposes are among the adaptation strategies to address the problem of recurrent floods. Exploration of scope to manage silt of Kosi river was identified as one of the key focus area for Action on Climate Today (ACT - a new programme of UK DFID) as agreed jointly by Government of Bihar (GoB) and ACT team. In this respect, a scoping study was conducted to estimate the deposited and extractable silt in various stretches of Kosi river and to make a commercial plan for usage of the dredged silt. BASIX Consulting and Technology Services (BCTS) was hired by ACT for undertaking this scoping study. As part of the study, BCTS team had discussion with various stakeholders such as farmers, community, local NGOs, brick manufacturers, government departments, research institutions, etc. The approach was Stakeholder consultation (through semi-structured interviews and focused group discussion), survey with farmers/HH (through scheduled questionnaire for 201 HH) and of local NGOs - Kosi Seva Sadan of Saharsa and Gramyasheel of Supaul (Key informant Interview), silt sample collection and analysis (40 samples of silt were taken. 7, 12 and 21 samples along with eastern embankment, mid of the river and along the western embankment were taken respectively), experimentation with silt sample for ceramic products (5 kgs and 10 kgs of silt samples were taken from the middle of river from the Kosi Barrage and sent to IIT-Varanasi and IIT-Patna respectively). The study shows that agriculture, livestock rearing and wage labour are the major livelihood options in both the districts. In Saharsa, 91% of low lands are badly affected due to water logging. In Supaul, 4% upland and 5% middle land are flood affected, while 77% of low land is waterlogged throughout the year. One or two members from more than 60% of families migrate. Migration was found to be higher among the “inside embankment villages” than “outside embankment. At IIT Kanpur, 20 silt samples were analysed as there was not much variation found in the analysis. Silt samples were aluminosilicate minerals, although all the samples were highly siliceous in nature. SiO2 content in the silt was around 66.36 to 80.15% and Al2O3 around 9.5 to 14.60%. Appreciable quantity of ferriginous impurities was noted in all the samples. High level of K2O and Na2O was noticed which will change the alkalinity of the soil. Silt samples were essentially aluminosilicate minerals with quartz inclusion. Major crystalline phase was quartz, feldspar (plagioclase, microcline) and hydrated mica was observed as major phase. In the sample taken from western embankment near the Nepal border has huge amount of mica/ illite. The soil test data pertaining to hundreds of farmers’ fields taken from all blocks In Saharsa District were obtained to study the existing soil fertility status by the Department of Soil Science, Rajendra Central Agricultural University, Pusa. The data indicates that the soils of the district are slightly alkaline. It was also observed that there is no significant difference in soil properties at different depths and among samples of different stretches. Embankments are not alkaline and it is suitable for most of the crops grown in the area. The soil test data of mid river soil and soils within east and west embankments indicates that organic carbon content in all stretches is low The soil analysis data indicates that majority of soil samples collected near both the embankments and mid of the river contains medium to high Phosphorous and are deficient with respect to micronutrients content. It was also found that all the samples were practically non-plastic in nature irrespective their sources. When ceramic products are made from its raw materials all raw materials invariably contain iron. It has inappreciable quaintly of iron oxide and TiO2. So, these silt samples can’t be recommended for utilization in high value ceramic products. FGDs conducted with local community of the villages nearby embankment revealed that most of the agricultural lands of the village are waterlogged for more than half of the year. About 98% of HHs migrated to other states. And therefore both agriculture as well as livestock have been hampered. Due to water logging for several consecutive months of year, Malaria and Filaria are prevalent. Women folk expressed that they are 2 Sediment Management in River Kosi – A Commercial Perspective 2018 overburdened as their partners migrate to other states in search of livelihoods. Women hardly find places to defecate. The villagers suggested that if the Government can fill their lands to make them upland, they will take care of converting the lands into agricultural lands. Local NGOs too suggested to use the silt of Kosi river for filling up waterlogged areas to revive the agricultural lands. An on-field survey and a proper drainage system have to be an integral part of the entire plan along with possibility of revamping sluice gates at the embankments. During the course of the study, various research and extension institutions were approached to obtain the information and expert opinion about the use of Kosi silt. According to Department of Ecology and Environment, Kosi silt is not suitable for usage in raising saplings as the silt is very fine and do not provide a conducive environment for seedlings to grow. Soil Scientists are also of view that the soils are loamy sand and poorly fertile which needs additional inputs to cultivate. Agronomy Professors also agreed that soil/ silts are having poorer soil fertility. Department of Road Construction, Saharsa suggested that sand/ silt of the river can be used for widening the road or increasing the height of the road and building paving blocks. ATMA team appreciated the idea of filling up waterlogged area with Kosi river silt. The usage suggested by CGCRI team includes pavement flooring, low value ceramic products such as Indian Pan, and brick making, provided mica is removed from the silt. Brick manufacturers informed that at present there are 200 flyash brick manufacturing units in Bihar with a cumulative installed capacity of producing 10 crore bricks annually. Some of them are in view that Kosi silt is not suitable for brick making as the silt is very fine. Results of chemical analysis of the silt sample by IIT Varanasi revealed that the low value ceramic products can be made from the silt. To make high value product, care should be taken during impurity removal, for which cost may be increased. Overall, the study is recommending that bulk usage would be dumping the Kosi silt in the agricultural fields which are low lying and prone to submergence during flood season. The silt can be used for landfills / deeply excavated fields for brick making, roadside excavated fields etc. The top layer of low lying lands dumped with silt needs to be improved to make it suitable for crop cultivation. It can be done by adding organic manures and scraped fertile silt where existing top soil is sandy and poor in terms of fertility status. After a few years of cultivation, the top layer of silt can be converted to fertile agricultural fields. 50, 000 ha of waterlogged land in Supaul district can be filled up with a layer of 3 ft consuming 90% of the extractable silt deposited in Supaul. All village roads also can be strengthened using the kosi silt. Likely benefits and impact include a) Increased area under agriculture and therefore Increased production and Income of HH, b) Enhanced availability of land for livestock, c) Reduced level of migration, d) Enhanced area available for villager to attend to nature’s call, e) Reduced level of prevalence of Malaria/ Falaria etc., f) Local entrepreneurship would be built, g) Reduced recurrence of flood, and h) Reduced level of Migration. 3 Sediment Management in River Kosi – A Commercial Perspective 2018 Table of Contents 1 Introduction ....................................................................................................................................... 8 2 Background ....................................................................................................................................... 9 2.1 Kosi and Floods ......................................................................................................................... 9 2.2 Estimates for Sediment Load and Volume of Extractable Silt ........................................................ 11 3 About The Study .............................................................................................................................. 15 3.1 Objectives and Outcomes: ........................................................................................................ 15 3.2 Approach and Methodology ...................................................................................................... 15 4 Socio-Economic Profile of the Region ..........................................................................................