Workshop on the Strategy and Action Plan of the WMO

Flood Forecasting InitiativeGeneva, 8 – 10 December 2009

Flood Forecasting Issues in Ghanaby

J. Wellens-Mensahhsd@ghana.com

FFI Workshop, Geneva, 8 – 10 December 2009

• Summary of Main Regional Conclusions for WMO Region I (Africa) contained in Doc.3 are mostly relevant to the Ghanaian Situation

• Additional Issues specific to Ghana include:Ghana experiences both urban and

rural/widespread floodinginadequate infrastructure, instruments and

equipment to collect and transmit hydro-met data in real time mode;

need for a network of calibrated radars for rainfall prediction and estimation;

FFI Workshop, Geneva, 8 – 10 December 2009

Ghana also experiences flooding from dam spills in upstream country;

These spills are beneficial for filling up reservoirs for hydropower generation, but causes severe flooding on way to the reservoirs

- need to synchronise spilling with conditions in downstream channels

- need for timely communication of scheduled, controlled and phased spilling from upstream country

FFI Workshop, Geneva, 8 – 10 December 2009

Flood Forecasts must save lives and limit flood damages; therefore forecasts should provide adequate warning and response measures

This, among others, requires delineation of flood plains in relation to flood magnitudes;

- need to combine GIS with DEMs- in turn, requires digitised topographic maps at

appropriate scale (currently exist in 1:2,500)Need to control development in delineated

natural flood plains eg. siting settlements and villages (keeping people and properties away from flood waters)

FFI Workshop, Geneva, 8 – 10 December 2009

Ghana has streamflow forecasting models for inflows for management of hydropower, potable water supply and irrigation reservoirs;

There is no comprehensive Flood Forecasting System, except for ad hoc warnings based on levels in rivers;

Need to develop end-to-end flood forecasting systems taking advantage of state-of-the art observing systems, data transmission, modelling (eg. using NWP inputs), transmission of flood warnings, scenarios generation and response measures.

FFI Workshop, Geneva, 8 – 10 December 2009

Thank you !