Irrigation Water Management

Irrigated agriculture in the dry zone of Sri Lanka is the most vulnerable yet the most important livelihood.  Compared to the very large number of minor reservoirs, there are a few medium scale reservoirs providing water to the dry zone.  Several transbasin diversions supply irrigation water to supplement the rainfall received in each area.  The largest diversion is from the Mahaweli river

Irrigated agriculture is a major livelihood not only in Sri Lanka but also in other regional nations covered by the SAARC.  A notable deficiency in most of the countries is the lack of standards, guidelines and, country specific parameters blessed by a central agency for planning design and maintain irrigation and water management infrastructure.

In the field of irrigation there is an urgent need to boost research.  Strengthening of estimating the watershed yield computations, Water efficiency/productivity, water losses from storage, water issues for cultivation etc., are the top priority areas when water management is concerned.

Presently, the irrigation department guideline is the principal document guiding not only the irrigation infrastructure development in the country but also other drainage infrastructure developments.  The coverage of specific subject areas and details is very comprehensive and the effort by Eng A.J.P Ponrajah in 1984 is commendable.  However, the data given and some parameters referred to in the guideline requires strengthening with evidence.  This is an urgent need.  Efforts to revise this guideline is a national duty of all policy makers because of the present status of the poor dry zone farmers who struggle to cultivate during both major monsoons.  There is an urgent need also to check the vulnerability of irrigated agriculture under the predicted rainfall patterns due to climate change.  UMCSAWM has carried out many problem based learning projects on the impacts of climate change on minor reservoirs in Sri Lanka. Also the UMCSAWM has a wealth of research on water productivity, water duty, reservoir operation etc., which can be added to the national database.  In all research UMCSAWM noted the data scarce situation to perform reservoir systems based studies. Some are the contour and detailed survey data of catchments, reservoirs and the command areas.  Canal wide water quantity measurement can be established with today’s low cost IoT technologies with sufficient research support.

Therefore, a policy decision must be taken to strengthen data collection programs in the irrigation sector without neglecting the minor reservoirs which serve the majority of vulnerable groups in Srl Lanka.  In parallel, an utmost important need is to update the present guidelines to irrigation infrastructure development guidelines.