“We want sacred rivers of Tawang to flow freely, not inside Tunnels!” What makes the assertion on this banner more remarkable is the fact that the people holding it up are not fiery activists, but peace-loving Buddhist monks of the Monpa community, from the farthest corner of Arunachal Pradesh: Tawang (photo by Urmi Bhattacharjee). About 13 hydropower projects are slated to come up on main river stem and tributaries of Tawang Chhu (River) in Tawang in a distance of just 160 kms.
Tawang is a tiny district of Arunachal Pradesh nestled between Tibet and Bhutan. The region has had a troubled past and is home to Monpa Buddhists who practice an ancient form of Buddhism. Monpa culture itself is unique and fragile, with less than 50,000 Monpas in Tawang and less than one lakh globally. The region is famed for Tawang Monastery, Galden Namgey Lhatse (which literally means Celestial Paradise on a Clear Night), which is the 2nd largest monastery in the world.
Although hunting for subsistence and culture occurs in the region, Monpa community is known for its evolved conservation ethic. In places like the Zemithang valley where 780 MW Nyamjang Chhu HEP of the Bhilwara group is slated to come up, locals have formed community conservation reserves to protect the Black Necked Crane which is not only a threatened bird, but revered as the reincarnation of sixth Dalai Lama for the Monpas.
In this tiny district of barely 2000 square kilometers, 13 hydro-electric projects have been planned by public and private proponents, damming and tunneling main stem and tributaries of the Tawang Chhu which will need 249 hectares of Forest land. Total capacity of these 13 projects will be 2890.110 MW. Of these, three projects are over 500 MW capacity, seven projects of 50-100 MW capacity and three projects of less than 50 MW capacity. See table below for details:
Monpa Protest against HEPs: People of Tawang have been protesting against these projects very strongly & for long. Unfortunately, their voices do not seem to be reaching the mainland. Brute force, beatings, imprisonment have been used against the protesting Monks, but the discontent in Tawang against the projects continue.
Cumulative Impact Assessment of Tawang Basin Projects Tawang Basin entirely falls in highly active seismic Zone V with a proximity to Glacial lakes. Geological, ecological and social uniqueness of the region means that the Cumulative impacts of this concentration of projects will be greater and more diverse than the individual impacts. Looking at the slew of Cumulative Impact Assessment (CIA) or Carrying Capacity Studies being churned out by consultants from Arunachal Pradesh, an unbiased and comprehensive CIA gains more importance.
Tawang Cumulative Impact Assessment and Carrying Capacity Study by NEHU: While considering the accordance of forest clearance for 750 MW Tawang-I and 750 MW Tawang-II projects, the Forest Advisory Committee (FAC) of the Ministry of Environment and Forests, (MoEF and CC) asked the Government of Arunachal Pradesh to conduct a study on Tawang river basin with the following objectives:
- To assess the impact of thirteen hydro-electric projects planned in the basin, ancillary industries/activities, including influx of migrant workers, displacement of local ST population etc., on local ecology and biodiversity,
- To assess the ecological water flow at different places along Tawang river and its tributaries.
- To prepare a biodiversity management plan at the landscape level for the river basin.
- To prepare a 15-20 years perspective plan for the cumulative development of the Tawang river basin.
- To assess carrying capacity of Tawang river basin.
Please find the Executive Summary of the Study here: https://sandrp.files.wordpress.com/2015/04/tawang-basin-study-nehu-exec-sum-sept-2014.pdf. The full report in two volumes can be found here: https://sandrp.files.wordpress.com/2015/04/volume-i-final.pdf and https://sandrp.files.wordpress.com/2015/04/volume-ii-final.pdf, must add that the files are very large.
The Government of Arunachal Pradesh in turn commissioned the North-Eastern Hill University (NEHU), Shillong for this. The Terms of Reference (TOR) of this study include:
- Impact Assessment of Individual projects
- Cumulative Impact Assessment: Cumulative Impact Assessment study for Tawang river basin
- Assessment of E-Flow
- Assessment of Carrying Capacity
- Twenty Year Perspective Development Plan for the entire basin including a disaster management plan.
- Landscape Level Biodiversity Management Plan for the entire river basin keeping in mind the possible damage to the biodiversity of the basin
NEHU involved other institutes like IIT Guwahati, WWF Tezpur, Foundation for Revitalisation of Local Health Traditions (FRLHT), North Eastern Regional Institute of Science and Technology (NERIST), and experts representing alumni/former faculty of Wildlife Institute of India (WII), SACON (Salim Ali Center for Ornithology and Natural History), Geological Survey of India (GSI) and Indian Council of Forestry Research and Education (ICFRE), etc., in this exercise. Main coordinator of the study is Dr. S.K.Barik, Department of Botany, NEHU, Shillong, Meghalay.
The study, known as “Perspective Plan for Development of Tawang River Basin: Cumulative Impact Assessment of Proposed Hydel Power Projects, Determination of Basin Carrying Capacity, and Landscape Level Biodiversity Management Plan” (Hereon referred to as Tawang CIA or CIA) began on 1st June, 2013 and continued till 31st July, 2014, the report is dated Sept 2014. Tawang CIA states that it was conducted “with participation of different stakeholders such as Tawang district administration, Zila parishad, political leaders, village council headmen and other villagers, and knowledgeable personalities, officials of Government of Arunachal Pradesh, and 4 developers representing 10 proposed hydel power projects. 52 subject experts were involved in collecting primary field data over a period of 14 months”.
According to the TORs, the study is divided into 6 sections as stated in the TORs given above. A brief overview of some the sections is below:
- Impact Assessment of Individual Impacts:
This section looks at individual impacts of the 13 projects and suggests project specific mitigation measures.
Projects recommended to be dropped at this stage include:
- THREE Tsa Chhu Projects (24 MW Tsa Chu-I, 77.2 MW Tsa Chu-I Lower and 67 MW Tsa Chu-II). Reason for exclusion is: “Being situated at very high elevation, the ecosystems are extremely fragile and difficult to recover and susceptible to hazards such as, high intensity landslides, soil erosion and GLoF.”
- 60 MW Thingbu Chhu is recommended to be dropped because “The proposed dam project would destroy substantial areas of land under forest and alter the river and adjoining ecosystems substantially. The identified site for the dam is highly unstable and landslide prone.”
This section also recommends strong mitigation measures for 780 MW Nyamjang Chhu Project in Zemithang Valley which is poised to affect threatened Black-necked crane and which is based on a compromised Eflows study by Central inland Fisheries Research Institute (CIFRI). The CIA recommends (From Executive Summary, Page VIII):
- “The proposed diversion of water from Taksang chu is not recommended. Taksang chu should be allowed to flow freely.” (Emphasis added)
- “Disturbing the lateral flow could affect the aquatic biodiversity in the downstream region which is critical for the livelihood of the people. A number of villages in the downstream region of proposed Nyamjang chu barrage are dependent on river for fish, molluscs, prawn and snakes. Therefore, adequate waterflow must be ensured for this downstream region. Given the amount of water to be released from the barrage, the lateral flow from 18 stream streamlets must be allowed naturally. This would also help in maintaining the biodiversity in the downstream areas.”
- “The proposed barrage site is about 1100 m upstream of the wintering habitat for the threatened black –necked cranes. Therefore, it is very important to strictly adopt some mitigation measures for the protection of its wintering ground to ensure the long term survival of this endangered species. This should include a wide range of measures ranging from maintaining prescribed e-flow, restricting the construction activities during winter months and minimising the noise pollution.”
2. Cumulative Impact Assessment
The Tawang CIA study looks at cumulative impacts from the perspective of ecosystems and impacts on Valued Ecosystem Components (VECS) and tries to understand the threshold values for cumulative impacts. Although VECs have been used in Cumulative Impact Assessment studies like Mekong in South East Asia, this concept which looks away from project-centered perspective to an ecologically or socially valued component perspective has not been used thus far in Arunachal Pradesh. Through this process, 31 possible effects of the projects have been taken into consideration, categorized in 6 types as given in table below:
While the approach is novel and good, the way it is implemented leaves a lot to be desired. For example, although the study states that Cross border cumulative impacts include dam break and its impact on Bhutan, no such dam break study actually addresses impacts on Bhutan.
Some of the issues not considered by the Cumulative Impact Assessment:
- Individual and Cumulative impact of peaking releases through HEPs in Tawang and downstream Bhutan not studied under hydrology.
- Downstream Impacts find no mention in the study.
- No mention of cumulative impact of blasting, tunneling, road construction
- No mention of the impact of change in silt regime on the river.
- Impact of mining for construction material in the riverbed
- Impact on local springs and water sources
- Impact on Green House Gas emissions, project wise and cumulatively.
- Impact of individual and cumulative muck disposal along rivers an its implications, especially during disasters like floods.
Scoring used to assess cumulative impacts is problematic at times when it is calculated in units of Per MW. This results in a situation where Forest Area Loss/MW in Jaswantgarh HEP, which needs 0.5 hectares of forest land, is higher than Nyamjang Chhu HEP which needs 50 hectares of forest land or Tawang I and II which need around 67 hectares of forest land. Similar is the case with indices of Carbon stock loss/ MW Production. Per MW based scoring for Intermediate River Length or river length diverte dper project has resulted in a situation where Thingbu Chu, which diverts 2 km of river, actually gets a higher impact score than Nyamjang Chhu which diverts 23 kms of the river!
There are also some issues in the way scores have been assigned. For example, the study assumes that long term impacts in operation phase for a component of River Bank Stability will be “None”.(Table III, 5.3). This is incorrect as peaking severely affects Bank Stability and in many countries opertaion of HEPs have had to be changed due to decreasing bank stability. Table III, 5.1 classifies cumulative impacts as Critical High, Low and Very Low Impacts. In this matrix, strangely, erosion and bank stability are “Low impact”. Net Primary productivity gets Very High Impact as well as Very low Impact!
There is ambiguity on the basis on which VECs and their components are selected and exactly how scores for cumulative impact were arrived at. There should have been a lot more clarity on this important aspect.
That said, the CIA section looks at and assesses hereto neglected impacts like cultural and livelihood impacts, assessing the dependency of the villages around the planned HEPs on the rivers or tributaries for various functions like domestic use, animals, fish, crabs, water snakes, frogs, snails, aquatic flora, religious uses, sand, stones (Section III 37). 95% of the households surveyed in the surveyed villages use river for performing last rites of the dead. The villagers depend on forest resources for 21 different uses.
This assessment is a welcome feature of the CIA Study and has not been attempted before in India.
61 Village consultations: Amazingly, the study claims to have held meetings in 61 affected villages to discuss the report and its findings and these are given in the report at Table III, 8.1. However, although the table makes it clear that most villagers area against the HEPs or are wanting more information about these, it is not clear if the concept of cumulative impacts have been explained to them. Although limited in its scope, this is a welcome aspect of the study.
The section concludes in following findings: “Thingbu chu project has the highest Cumulative impact on the Ecosystem aspect followed by Nykcharang chu and Tsa chu. Biodiversity aspect is impacted most by Rho, Mago chu and Thingbu chu. The projects highly vulnerable to hazards are Rho, Nykcharang chu, Tawang I and Tawang II. New Melling is having high impact on Hydrological aspects followed by Tsa chu I,Tsa chu II and Thingbu chu. The projects having highest impact on livelihood are Tsa chu II, Paikangrong, Nykcharang chu and Nyamjang chu. Cumulatively, Tsa chu II is having the highest Standardized Cumulated Project Effect Index (SCIA) value of 0.95 followed by Tsa chu I, New Melling, Thingbu chu and Tsa chu I Lower.”
3. Assessment of Environmental Flows:
The way the study has treated Environmental Flows is a departure from the past studies.
Most of the past studies have made a hash of this very important concept. WAPCOS in its Lohit River Basin study and Bichom River Basin study had made a joke of eflows by stating that they have used Building Block Methodology (BBM) for recommending eflows. BBM is a sophisticated methodology which looks at river flows as building blocks for various riverine processes and dependencies and recommends several such building blocks for services like fish and biodiversity, fluvial geomorphology, water supply, cultural and aesthetic needs, etc. On the other hand, RS Envirolinks Eflows assessment looked only at a single species like Snow Troutand tailored all the eflows requirement centering around this single fish for river basin which have more than 200 fish species. Eflows recommendations of some agencies like Central Inland Fisheries Research Institute (CIFRI) were so compromised that these would only lead to destruction of hereto free flowing rivers. The MoEF and CC nonchalantly accepted all these recommendations without raising any questions, setting any standards or conducting any studies on its own.
In this scenario, the Tawang CIA has based its eflows recommendations on Building Bock Methodology which considers following blocks:
(i) River biodiversity based on fish species like Schizothorax richardsonii, Schizothorax sp., endemic species (endemic periphyton, endemic zooplankton), and threatened bird (Black necked crane)
(ii) River hydraulics (bed composition),
(iii) Cultural requirement (dead body disposal and the habitat requirement of black necked crane)
(iv) Livelihood requirement (water use, river resources, and edible Algae) and
(v) Ecosystem structure and function (periphyton density, water quality, NPP, invasibility by invasive alien species (IAS).
For all these above components, the study assigns Water depth, Width and velocity and then computes necessary flows in Lean Season (Season of Low water levels: December, January, February and March), Non Lean and Non Monsoon Season (Intermediate months of October November and April May when there is some residual flow) and Monsoon Season of June July August and September.
This is the first Indian study I have come across which assigns values to Livelihoods requirement and cultural requirement. The study should have specifically mentioned that these flows should be mimicking real time natural hydrograph and should be released as such and not on a daily/ weekly/monthly or seasonal basis which will defeat the purpose of e-flows.
The percentage flows recommended by the study are given below:
- 780 MW Nyamjang Chhu Project:
The study has recommended higher eflows for Nyamjang Chhu HEP as against the extremely low eflows recommended by CIFRI. This has been done expressly for Cultural Values, Livelihood Values and to protect the wintering habitat of the Black Necked Crane. In fact, the study states ( Page XIV, Volume I) “Considering the conservation importance of Black Necked Cranes, the experts were unanimous to protect the habitat of the species in the downstream area of Nyamjang chu barrage axis. In order to achieve this, e-flow of 10 cumecs during lean season was fixed that would adequately maintain the river flow surrounding the bird s’ present habitat. In addition, it was decided that at least 27 Cumecs of water should be made available in the downstream area during the remaining months of the year to maintain the habitat characteristics. In fact, the habitat requirement of black necked crane was the deciding factor to determine e-flow in Nyamjangchu project area.” (Page xiv, Volume I) (Despite this unambiguous wording the actual flow recommended in non-monsoon and monsoon months is lower than 27 cumecs)
Further, to minimize the disturbance to the birds ‘arrival during October-December, it has been recommended that:
(1) No construction activity will be undertaken during October-December months during construction phase,
(2) No activity beyond 50 m of the barrage axis in the downstream area will be undertaken,
(3) No water will be harvested from the river Taksangchu to maintain the lateral flow in the river. In addition, the project proponents should strictly follow and adopt other mitigation measures as suggested to minimise the impact of noise pollution (drilling, blasting and tunnelling), water pollution, regulating of vehicle movements and impacts from of labour force.” (Page xiv, Volume I)
The minimum environmental flow requirement for three seasons at Nyamjang chhu project site as per the CIA are:
- Lean season: 10 cumecs
- Non-monsoon season: 10 cumecs
- Monsoon season: 23 cumecs
Flow requirement for various VECs in Nyamjang Chhu are stated in the table below:
CIFRI’s Shocking Eflows Study for Nyamjang Chhu HEP: It is important to note that Central Inland Fisheries Research Institute (CIFRI), a centrally funded premier institute on Inland Fisheries was entrusted to carry out an assessment of Environmental Flows for Nyamjang Chhu Project as a part of its Environmental Clearance process. CIFRI recommended a blanket flow of barely 3.5 Cumecs from the Barrage in lean and non-monsoon months.
CIFRI has also allowed for the complete diversion of Taksang Chhu River, but it feigns complete ignorance about the fact that an entire river will be diverted for this project.
Most shocking is the difference between the cross section of the barrage site which is an important criteria for the recommendation of environmental flows as it affects river hydraulics, top width, velocity and water depth. It is shocking to see that CIFRI final report shows river cross section at Nyamjang Chhu as a featureless channel while the NEHU Basin Study indicates a more realistic cross section of the river. Prima facie, it looks as if CIFRI’s eflows report is based on incorrect (manipulated?) cross sections and should be rejected outright by the MoEFCC. In fact, SANDRP had pointed this out to the EAC in its submission, but the EAC did not even take a note of this anomaly. The CIFRI should also be blacklisted for doing such misleading and doctored study.
Below: Cross section of the river at Zemithang as per CIFRI Report
Cross section of the river at Zemithang as per NEHU Tawang Basin Study
- Assessment of Carrying Capacity of Tawang River Basin
From the report: “Carrying capacity in the ecological context is defined as the threshold of stress below which populations and ecosystem functions can be sustained. The carrying capacity has been assessed by considering combined social and environmental impact threshold, human population influx threshold, E-flow, free-flow river length and forest loss threshold. The following parameters were identified as indicators for determining carrying capacity of Tawang river basin: (1) basin zonation, (2) human population influx, (3) prescribed E -flow based on availability of water at different points, (4) forest/vegetation loss, and (5) combined socio -environmental index.
Threshold limits considered for Carrying Capacity Study include:
- 50 percent of the main river length should be free-flowing i.e free of any projects,
- 66 percent of the total geographical area will be under forest cover,
- The total population of Tawang at any given point of time should not exceed 33% more than the present population i.e. 65,000 persons
- No projects above 2500 m asl should be constructed.
- Minimum level of water flow must be maintained round the year to ensure the sustainability of the river ecosystem structure, function and services.
The projects which did not meet this criteria have been recommended for rejection.
These include: 24 MW Tsa Chhu, 77.2 MW Tsa Chhu I Lower, 67 MW Tsa Chhu II, 60 MW Thingbu Chhu and 90 MW New Melling HEP
- Phasing of projects: “In order to keep the developmental activities within the carrying capacity of the basin and for diffusing the impact both spatial and temporal segregation of the construction phase is suggested. Parameters considered for phasing were: to maintain the influx of population within the carrying capacity limit, i.e. presumed to be 33% increase from the base population.
Phase I (0-5 years): Nyukrangchu, Tawang II, Nyamjangchu, Jaswantgarh and Paikangrong
Phase II (5-10 years): Tawang I, Rho, and Mago Chu
5. Biodiversity Perspective plan for Tawang Basin The perspective plan consists of several mitigation measures , some which are highly questionable like nest box erecting (without any scientific study and limited bird species), however, project specific plans like suggestions for protection of Black Necked Crane in case of Nyamjang Chhu project are important.
Conclusion and Recommendations of the Tawang Basin Study
- The projects proposed above 2500 m asl would not be implemented in the river basin. Under this criteria, Tsa Chu I, Tsa Chu I Lower, Tsa Chu II, Thingbu Chu and New Melling should not be implemented.
- The projects with the cumulative impact assessment index value >0.84 would not be implemented. Under this criteria, Tsa Chu I, Tsa Chu I Lower, Tsa Chu II, Thingbu Chu and New Melling should not be implemented.
- The e-flow as recommended should be maintained by all the projects recommended viz. Nykcharong chu, Tawang I, Tawang II, Nyamjang chu, Rho, and Mago Chu. The design discharge, power generation and peaking hours need to be modified accordingly.
- The recommended 6 large hydro projects and the 2 small-hydels viz., Nykcharong chu, Tawang I, Tawang II, Nyamjang chu, Rho, Mago Chu, Jaswantgarh Stage I and Paikangrong should be implemented in two phases as follows: Phase I (0-5 years): Nykcharong chu, Tawang II, Nyamjang chu, Jaswantgarh and Paikangrong; and Phase II (5-10 years): Tawang I, Rho, and Mago Chu.
- The mitigation measures recommended by the report should be implemented to minimize the adverse impacts of the projects.
Project Specific Recommendations:
1. Nykcharong Chu and Rho
- The construction activities should be planned in such a way that no existing forests and habitats of the biodiversity are destroyed. If required, the ancillary construction activities may be relocated to save the old growth forests (e.g., colony site of Rho project).
- Adequate care must be taken to save the tourist place e.g. Nuranang Falls from the adverse impacts of dam construction and also during operational phase.
- Drinking water sources for all the influenced villages must be ensured.
- Advanced and appropriate machineries should be used to minimize ground vibrations during construction phase.
- The habitats for birds must be protected. The host plant species should be planted under various afforestation programmes and artificial nest boxes must be installed in sufficient numbers. ( This is a problematic and non scietific mitiagtion measure.
4. Nyamjang Chu : Recommendations have been listed above
To sum up, the Tawang CIA/ Perspective Plan/Basin Study is indeed a unique attempt in Cumulative Impact Assessment which is a departure from consultant-centric, isolated Basin studies so far. This study has robust primary work on some topics like Eflows.
That said, the study shies away from recommending dropping any bigger projects, despite their issues. Factors in scoring system based on per MW score have contributed to this. For example, In case of 780 MW Nyamjang Chhu Project, the CIA agrees that the project has severe impacts on social, cultural and ecological aspects: specifically nesting of Black Necked Cranes and it is impossible to shift the barrage site in any other place. Such a direct stalemate means that the project should be dropped, but NEHU has shied away from making such a recommendation. This was also seen in Siang Basin Study also wherein the consultant dropped smaller projects to gain some brownie points but did not recommend dropping bigger projects on the Siang Main stem like Lower Siang or Siang Upper I or II, accepting them as fait accomplii. This inhibition does not serve the purpose of a credible Cumulative Impacts Assessment.
The CIA has not highlighted the strong protests against the projects, the cases filed against projects like Nyamjang Chhu and concerns of groups like Save Mon Region Foundation
Tawang Perspective Planning and Cumulative Impacts Assessment is also a social process and should undergo a free prior and informed consent of the people of Tawang and a comprehensive Public Hearing. It should also be noted that all of the projects will operate in peaking mode, and will lead to impacts in the downstream, which will reach upto Bhutan., which are not studied. As the study says, we share excellent relations and hence it is our responsibility to assess impact of peaking across the international boundary also. We hope these concerns are addressed.
We hope that the Cumulative Impact Assessment/ Carrying Capacity Study and Perspective Planning of Tawang is disseminated throughout the region in local language and is improvised with inputs from inhabitants of the region. It will not be prudent to take up any projects without this process, else the stalemate at Lower Subansiri project is likely to be repeated.
In the meantime, Environmental Clearances given and future process of Nyamjang chhu and Tawang Basin Projects will have to be kept in abeyance unless the proponents accept the eflows and other mitigation measures recommended by the CIA.
In case of Nyamjang Chhu, CIFRI eflows report which uses misleading cross sections and which also willfully ignores diversion of a complete river, needs to be rejected and the organization made accountable for this doctored study. Environment Clearance granted to 780 MW Nyamjang Chhu project based on this study needs to be quashed urgently.
Tawang CIA and Perspective Study done by NEHU is an encouraging attempt and we hope it will be improvised to give voice to the peace-loving and ecologically sensitive people of Tawang.
-Parineeta Dandekar, firstname.lastname@example.org
 CIA, Page V-9
4 thoughts on “Cumulative Impact Assessment of Tawang Basin: Highlights from the NEHU Study”
Good review. Thanks. Nice to see good science slowly entering the area of impact assessments.
If we poach nature on development tag, nature curses every body,please say ‘No’ dams construction where people(sons of the soil) opposes for the well being of the posterity.
This is the best report on the proposed project in tawang, I am enlightened in the best possible way and i thank you for that,being a native of this place I strongly oppose the governments initiative and agencies involved for thieir relentless efforts to destroy my place in the disguise of development and welfare of my people. We have and will live in the dark(without light) if this is what is demanded for our bright future.