Introduction

Sri Lanka can be divided into two main meteorological zones; the wet zone and the dry zone. This division is result of the two rainy seasons, the north-east monsoon and the south-west monsoon. The south-west monsoon, is activated during May to September brings more rainfall than the north-east monsoon that is activated from December to February. The elliptical orbiting of earth locates the sun directly above Sri Lanka twice a year, once in March/April and again in October. However, in addition to these weather changes, the wind pattern, coupled with ocean-atmosphere phenomena El-Nino and La-Nina creates

sudden changes in weather.

 

The dry area gets lesser rainfall from north-east monsoon period and the months following have less or no rainfall. Therefore, there is a probability for a drought to occur in the area. It has been observed in the recent past that impacts of several droughts were recorded in the dry zone and large amount of economic crops were reported as damaged due to the drought situations. Therefore, prediction of the droughts in the dry zone is essential for the livelihood of inhabitants. Such prediction would enable proper management of economic crops and it will correlate to the poverty reduction of the area. In addition, 20% of total electricity generated in the country is supplied from the hydropower. Therefore, development of drought assessment tool is needed for the country to take important decisions to the professionals.

 

Objective

The main objective of the research study is to develop a drought risk identification tool to understand the drought severity levels for local level decision making professionals.

 

There is no exact definition for the drought hazard. In Sri Lanka, a drought period is normally considered as a prolonged period of time (say more than 8 months) without rain. However, drought can be managed by controlling the water requirements in the settlements. Sri Lanka had such experiences during the historic time that had managed the water by massive irrigation systems. 

 

        Drought Indices 

There are several drought indices which are used to explain drought scenarios and to ascertain causes or activities that aggravate adverse impacts. Drought is typically classified as Meteorological Drought, Agricultural Drought, Hydrological Drought and Socio-Economic Drought (Fernando,W.B.J.,NBRO NewsletterVol3,Aug. 2010). Most of the commonly used indices are designed to identify the Meteorological droughts. However, as Agricultural drought indices are combined with agricultural activities, they are more useful to developing agricultural countries like Sri Lanka.

 

National Building Research Organisation (NBRO) in collaboration with Vanderbilt Institute for Energy and Environment (VIEE) started a research project to forecast climate change predictions on water balance in Mahaweli catchment area and it will be linked to agricultural adaption on climate change impacts, and droughts. Under the collaboration, NBRO expects developing a local supportive information system on drought that can provide support to the professionals to take their decisions. The drought impacts will be predicted by using the Palmer Drought Severity Index (PDSI) and this has been accepted by the stakeholders of the project.