An independent report claims so 

Hydropower: The two hydropower plants of Tala and Chukha has left a 35km stretch of the Wangchhu practically dry with very limited water flow, an independent study says.

The study conducted a land-use change mapping using post-monsoon satellite images covering a region of 10km around Chukha, Tala, Punatshangchhu-I, II and Mangdechhu.

The report published by Vasundra foundation, a non-profit organisation in India stated that post-monsoon imageries are ideal for mapping water-flow regimes.

However, results for the Punatshangchhu I, II and Mangdechhu did not delineate significant information as the construction of these projects are on-going.

In case of Wangchhu, the land-use change map revealed that a 10km stretch from the Chukha head-race tunnel and another 25km stretch from the Tala head-race tunnel are dry. The fact that the Tala head-race tunnel is within a 2.4km distance form the Chukha tailrace tunnel means that the two projects together affect a stretch of 35km.

“This can severely affect the riverine ecology of Wangchhu and have irrevocable implication for ground water aquifers and ground water recharge in the region,” the report states.

The Kurichhu, being a reservoir scheme, without diversion of river course through tunnels, does not have much impact. But the reservoir schemes, according to the report will submerge a greater amount of land depending on the capacity.

The environmental impact assessment (EIA) for Chukha, Kurichhu and Tala, the report claims was not conducted as these projects began prior to the passing of the Environmental Assessment Act in 2000.

Bhutan does not have specific norms and standards to maintain adequate environmental flow of rivers while implementing hydropower projects.

Environmental flow is a system that manages the quantity, timing and quality of water flowing downstream of a dam.

The National Environment Commission, the report states, is currently working to scientifically determine environmental flows and hopes to come out with one in 2017.

While the forest protection norms do not allow any activity in the areas identified as core zones, the report quotes an official from the Department of Forest and Park Services as implying that they apply subject analysis based on ground realities.

For instance, underground drilling was permitted in the buffer zone of a reserve park in case of the Nikachhu project. Transmission lines through forest and protected areas, for example, has very little impact on forest covers and watersheds.

The report also points out that the Punatshangchhu I, II, Chukha, Tala and Kurichhu projects are located in areas identified as high and very high seismic active zones, besides potential risk of GLOF.

Notwithstanding this fact, the report also mentions that the Department of Disaster Management has no specific focus on hydropower projects and it is also not mandatory for project authorities to be involved in drawing disaster management and contingency plans.

Even with three on-going mega projects in Wangdue and Trongsa, it is pointed out that preliminary information indicates environmental aspects of the project component are taking a backseat.

Tshering Dorji