Nishadi Eriyagama

Global Environmental Flow Information for the Sustainable Development Goals

Environmental flows (EF) are an important component of Goal 6 (the ‘water goal’) of the Sustainable Development Goals (SDGs). Yet, many countries still do not have well-defined criteria on how to define EF. In this study, we bring together the International Water Management Institute’s (IWMI’s) expertise and previous research in this area to develop a new methodology to quantify EF at a global scale. EF are developed for grids (0.1 degree spatial resolution) for different levels of health (defined as environmental management classes [EMCs]) of river sections. Additionally, EF have been separated into surface water and groundwater components, which also helps in developing sustainable groundwater abstraction (SGWA) limits. An online tool has been developed to calculate EF and SGWA in any area of interest.

Actual and perceived causes of flood risk: climate versus anthropogenic effects in a wet zone catchment in Sri Lanka

ABSTRACT The Kalu Ganga Basin in Sri Lanka is generally flooded once a year. A network of low-lying lands acts as natural retention and storage that captures floodwater, minimizing damage. An increase in the flood frequency has been observed in recent years. It is commonly perceived that this increase is caused by a rise in the frequency and severity of ‘very wet’ precipitation events. We conclude that land-use changes may have played a larger role in generating floods.

Trend and variability of rainfall in two river basins in Sri Lanka: an analysis of meteorological data and farmers’ perceptions

ABSTRACT Selected rainfall characteristics derived by analyzing observed rainfall data in two Sri Lankan river basins (Malwathu Oya and Kalu Ganga) were compared with the perceptions of farmers. The rainfall characteristics used for this analysis are trends, onset and cessation dates, length of the growing period, number of rainy days, and length of the dry spell. Farmers’ perceptions of changes in those characteristics were collected through household surveys. The majority of farmers in both river basins failed to recognize the long-term upward trend in annual rainfall. They also failed to describe the adaptation measures they were currently practising.