PROBLEMS RELATED FLOOD IN

RATNAPURA DISTRICT

GROUP No: 18

What is floodingReasons for floodFlood risk in countryWhy RathnapuraSide EffectsSolutions

CONTENTS

WHAT IS FLOODING

Heavy rain Rivers is floating through cities Unplanned drain water systems surrounded by mountains Filling valleys for human needs Taking sand from rivers Mining Tea plantation Unplanned development projects

REASONS FOR FLOOD

 Flood  Hazard Map

Heavy rainfall in the Eastern and South-Western slopes is a principal cause of the flood risk.

the drainage and topography of certain districts and land use patterns are also significant factors.

The Western slopes receive rainfall in both Maha (September to January) and Yala (May-August) seasons, and is prone to flooding in these periods.

The Eastern slopes receive most of the rainfall during the Maha season (September to January).

The District of Vavuniya shows a higher flood probability due to cyclonic storms.

FLOOD RISK IN COUNTRY

This is the place where flooding appear mostly in sri Lanka

frequent flooding, landslides, soil erosion and land subsidence due to gem mining, pollution and contamination of water supplies.

Annually, two major floods occur in Ratnapura– during May-June and September-October. High rainfall and flooding of the Kalu river often cause damage in the central business district as well as outlying areas. Large floods usually occur once in every 8 to 10 years. Big flood occurred in 1979, 1984 and recently in May 2003

WHY RATHNAPURA?

Ratnapura town is located at the confluence of Wey (Ganga) River

with Kalu (Ganga) River. Since both catchments consist of areas

with high slopes, the city gets flooded within a duration of 24 hrs.

in an event of high rainfall within the upper catchment area.

WHY RATHNAPURA? Cont..

Rating Curve of Kalu Ganga at Ratnapura

CURVE

DAMAGE TO LIVES & PROPERTIES IN 2008

LAND SLIDE Disease Displacement Sanitary facilities Diarrheal diseases and viral flu diarrheal and amoebic diseases including

dengue and Japanese encephalitis. school uniforms and text books children

affected by the floods

SIDE EFFECTS

the increasing number of landslides, was due to lack of proper planning in developing landslide prone areas, “the authorities should make proper plans, when they implement development plans in sensitive areas

When people are involved in indigenous agricultural methods (Hen govithen), the bare land is exposed in slopes and the water is absorbed

when it rains heavily, the bare land would not be able to withstand a large amount of water. Therefore, landslides occur.

they do their development programs in sensitive areas, but the majority of them do not follow the recommendations

LANDSLIDES

Early Warning and Evacuation System Installing pumping stations (there are 10 on

the GinGanga flood plains and three on Nilwala)

And erecting concrete walls on either side of the river beds along flood prone areas.

SOLUTION FOR FLOOD

Identification of suitable alternative lands. Demarcation of land. Selection of families for allocation of land. Financial Assistance to Build Houses. Technical assistance. Labour input.

RELOCATION OF EFFECTED FAMILIES

A flood simulation model has been developed to predict water level along the river stretch from Ratnapura to Kalutara for different water flows in the river.

Setting up Flood Forecasting and Early Warning Systems for Kalu River basin

Early Warning and Evacuation

Early Warning and Evacuation

utilizing satellite, GIS and information network technologies as much as possible,

enhancing the development of the basis for sharing information on flood risks and disasters among national and international organization in relation to flood management,

and realizing the above concepts on the Sentinel Asia network system

To contribute to the mitigation of flood disasters

What is floodingReasons for floodFlood risk in countryWhy RathnapuraSide EffectsSolutions

SUMMARY