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Enhancing flood forecasting and warning systems in Bhutan

Date 17–20 February 2020
Venue Thimphu, Bhutan
Contact Persons servirhkh@icimod.org
Type Workshop
Programmes SERVIR-HKH, MENRIS

ICIMOD implements the SERVIR Hindu Kush Himalaya (SERVIR-HKH) Initiative in its regional member countries, prioritizing activities in Afghanistan, Bangladesh, Myanmar, Nepal, and Pakistan. Through SERVIR-HKH, ICIMOD has designed and developed a suite of forecasting tools that spans timescales and informs decision making for flood preparedness and proactive response. The High Impact Weather Assessment Tool (HIWAT) and the European Center for Medium Range Weather Forecasts (ECMWF)-based flood prediction tools and South Asian Land Data Assimilation System (SALDAS)-based sub-seasonal to seasonal forecasts present unprecedented opportunities for an integrated end–to–end flood forecasting system that extends current instrumental lead times into seasonal timescales. The tools use ensemble runs using perturbed physics and sample initial and boundary condition distribution to constrain uncertainties and provide a probabilistic forecast for improved decision making.

A four–day training workshop will be organized jointly by Bhutan’s National Center for Hydrology and Meteorology (NCHM) and ICIMOD, aimed at raising awareness of the tools and developing capacity in using the tools as a source of more reliable guidance underpinning operational forecasts. The workshop will also impart basic skills on forecast interpretation and evaluation and translating forecasts into impact-based outlook, watch, and warning for exposure assessment and verification.

Objectives

Though Bhutan is not included in the present phase of SERVIR-HKH activities, it still falls within the forecast domains of these tools. Prediction outputs over Bhutan only require extra routines in post–processing and analysis. Scaling the use and benefits of the tools for Bhutan is consistent with ICIMOD’s strategic goal of diffusion and adoption of innovations and practices and builds on participants’ expressed interest at recent ICIMOD events.

The training workshop will achieve the following objectives:

  • Present SERVIR-HKH flood forecasting tools as a decision-support solution to emergency managers and national agencies responsible for flood management and water stewardship, while sharing experiences and feedback from other users in the region and beyond
  • Develop capacity of the NCHM in the use and deployment of tools in flood monitoring and access forecast information for more reliable and credible guidance in formulating early warnings
  • Strategize and plan for integration of the tools into existing operational flood forecast and warning systems
Expected Outcomes

Flooding, largely triggered by convective or advective precipitation, occurs almost annually in Bhutan. The flood-prone hydrography is defined by its rugged terrain and monsoon-dominated seasons that frequently spawn thunderstorms of varying duration, intensity, and areal extent. The natural drainage basins are comparatively small and steep with fast hydrologic response to precipitation, resulting in mountain torrents that pose threats to lives and assets downstream.

Epic floods reported through history have not only claimed lives and wreaked destruction but also changed the face of the Bhutanese landscape. Cyclone Aila caused the widespread deluge of May 2009, leaving behind a trail of suffering and destruction with 12 people dead and USD 17 million in damage. While it is not possible to stop natural floods from occurring, effective and comprehensible early warning systems can help mitigate the impacts, reduce associated risks to lives and properties, and provide reasonable foresight.