Alarm relay at Tsho Rolpa
Alarm relay at Tsho Rolpa Chronology of Tsho Rolpa GLOF Hazard Response |
In June, 1997, HMG installed five locally-manufactured siphons. On September 4, a large wave from a calving glacier severely damaged one of them. At the end of June 1997, HMG installed an early warning system at Tsho Rolpa. This was followed by the establishment of army and police camps at Na, two hours below the lake, and on the Tamba Khosi, the river into which the Rolwaling empties. In the event of a GLOF, a warning was expected to be broadcast by Radio Nepal. Soon, however, the police and army camps were withdrawn.
In January 1998, the Canadian company BC Hydro International, Ltd. (BCHIL) and the American Meteor Communications Corp. (MCC)
sent a team to install both early and relay warning systems in
Rolwaling. in January 1998 for the Government of Nepal. In April and
May, six water level sensors were installed along the river channel
immediately downstream from Tsho Rolpa to detect the onset of a breach.
(Due to the instability of the moraine, sensors had to be designed to
detect actual outflow rather than movement in the moraine.) A "control
logic" application associated with the sensors was designed to screen
out false alarms resulting from malfunctions. Breach warnings would be
transmitted from two stations installed at a higher elevation. Within
two minutes of flood initiation, a GLOF event would be detected,
relayed, and received by all 19 warning and relay stations downstream.
Each station is powered by a 12V battery charged by a solar panel, and
the alarm would trigger an air horn backed up by an electronic siren.
The alarm is supposed to give people within earshot a few minutes to
scramble uphill, out of the way of the impending flood.
This fully-automated system is based on MCC's Extended Line of Site (ELOS) VHF radio technology. A second component total package is an MCC Meteor Burst Master station which is supposed to be located in Dangadi, western Nepal. [While we can confirm that the Rolwaling relay stations are in place, Bridges has not confirmed the completion of the Meteor Burst Master station.] According to MCC,
| a meteor burst station uses the ionized trails of meteors to extend the range of the transmitted radio signals to over 1,000 miles. Several of the warning stations, as well as a sensing station, transmit and receive signals from the Master station, to provide further redundancy to the system. The Master station also monitors the status of the entire warning system. ... [It] will give HMGN the capability for remote weather monitoring and two-way data communications covering over 80% of Nepal. |
Map published on MCC's Website
Despite the automated design of the warning system, the system itself must be monitored to make sure that it is functioning correctly.