On Wednesday the 13th of February, while most of us were getting ready to celebrate Valentine’s Day, Mauritius was hit by extreme climatic conditions: torrential rain conditions prevailed on the island and as early as 06h15, the intensity of the rain was so high that the Meteorological Station of Vacoas issued a torrential rains warning. It was followed by a communiqué from the Ministry of Education ordering the temporary closure of all educational institutions.
By 10h00, public sector employees and some minutes later, private sector employees as well, were told to return back home due to flooding of major road networks of the island. The main question would thus be: how is it that each and every time that there are heavy rains, the island is somewhat paralyzed due to consequent floods?
Floodplains and Flood Prone Areas A flood plain is an area of land that is prone to flooding. Flood prone areas are those areas which are low-lying, with a history of flooding. Hotspots, on the other hand, are areas which are not low-lying but had experienced flash flood. They are in fact classified into 2 categories: firstly, those affected by natural flooding as result of residual deposition of water from rivers. The second category implies flooding caused by human activities due to the transformation of natural landscapes by mankind.
The Mauritian Drainage System
Due to the major issue of flooding of most of the drainage network following torrential rains, the Government commissioned a study carried out by GIBB MAURITIUS geared towards the Mauritian drainage system publicly released in April 2003. The report was in relation with the topology of the island, the actual situation of soil and forestry, erosion, flood-risk zones and installation costs of drainage systems.
Further to that study, several causes of floods have been identified. After studying the texture of the soil and land-use, according to GIBB’s report, the damaging effects of flooding depend on the hydraulic capacity of channel networks, rivers and secondary watercourses. The outcomes of this study are numerous but it is obvious that the problem remains unsolved. Unplanned and rapid urbanization of the island with inadequate drainage system have worsened the situation. While in March 1999, a total number of 169 flood-risk areas have been identified, this number has approximately doubled to reach 326!
Several factors linked to human activities have brought about floods in many flood-risk zones in residential areas. Within those factors, poor-quality drainage systems either in their construction or design; or even a total lack of drainage system; pipe networks obstructing water run-off after heavy rains; construction of buildings below flood level of rivers or next to river banks: a major deficiency put forward by the study is that drainage systems have been constructed without due preliminary studies on the suitable dimensions of those drains. The construction of settlements on mountain slopes has indeed increased the risks of flooding.
According to GIBB MAURITIUS, Mauritius does not have a national acceptable design criteria or guidelines for the design of flood and drainage related structures and facilities. The creation of a Land Drainage Coordination Committee has been put forward having as main functions to issue standards related to the control of floods, the actual drainage system and to cater for the needs of citizens in case of ecological problems. It should be noted that this committee has been dismantled and to a certain extent, this has given rise to a certain chaos when it comes the construction and management of drains. For certain projects, undersized drains useful only during normal rains have been built whereas, when torrential rains prevail, these drains are useless to evacuate surplus water run-off.
Moreover, the local authorities are equally to blame. They are accused of being too permissive when allocating building permits for real estate development projects without taking into account the standards and requirements regarding the drainage systems of rain water. In most of the cases, municipal and district councils tend to limit themselves to road-side drainage systems which are in most cases, inappropriately dimensioned.
From 2008 till now, the Government has invested up to Rs. 2, 5 billion in the construction of drainage systems throughout the island but it has been noted that people often dump their wastes into them thus causing their obstruction and consequently flooding during heavy rains. According to the Minister of Public Infrastructure, Honorable Anil Baichoo, the Government shall continue to provide for additional drainage networks but that it is the responsibility of each and every citizen to take care of those drains and not to obstruct them by dumping or poorly planned construction projects.
Despite all those recommendations, studies or committees, the conclusion is clear-cut: le problem remains recurrent and not later than Monday the 18th of February, the northern part of the island experienced flooding which as usual, has affected the daily life of many villages that were flooded!
Written By
Dany Gowsee
Photos: https://www.facebook.com/Lacasemu
