COLOMBO, 5 June 2008 (IRIN) - Flash floods that affected 418,000 people and left 23 dead and four missing this week in western Sri Lanka could have been avoided with proper water retention schemes, government irrigation engineers told IRIN.

Floods caused by the onset of the southwestern monsoon on 2 and 3 June affected more than 94,000 families in nine districts in the western lowlands, GM Gunewardena, assistant director at the National Disaster Relief Service Centre (NDRSC), told IRIN.

"The worst-hit area has been the Kalutara District, where over 150,000 people have been affected in some of the low-lying areas close to rivers," he said.

Deaths and disappearances

According to a joint situation report released by the government and the Inter Agency Standing Committee (IASC) on 4 June, 12 of the 23 deaths and three of the four flood-related disappearances were reported from southwestern Kalutara district.

Engineers at the Irrigation Department of Sri Lanka, which monitors floods, told IRIN the low-lying areas of Kalutara and other adjoining districts were submerged because they were in the flood basins of rivers that burst their banks after heavy rains.

"The rivers run down steep slopes in the hills, so water gains speed," BK Jayasundera, senior deputy director at the Irrigation Department in charge of flood protection, told IRIN. "On the low-lying areas there is less [of a] slope and when there are heavy rains the water rushes down," he said. "Unfortunately these areas have also become over-populated."