Estimating irrigation-induced changes of water and salinity levels in Karagan Lewaya lagoon, Sri Lanka

Show simple item record Stanzel, Philipp 2015-08-10T19:05:28Z 2015-08-10T19:05:28Z 2002-09
dc.description The table of contents for this item can be shared with the requester. The requester may then choose one chapter, up to 10% of the item, as per the Fair Dealing provision of the Canadian Copyright Act en
dc.description.abstract The imminent extension of the large-scale Uda Walawe irrigation scheme in the south of the tropical island of Sri Lanka will have serious ecological effects on the development area. The International Water Management Institute is trying to assess these effects by a long-term study, in which the pre-development status is investigated and the changes are monitored in biological, hydrological and water quality and socio-economic surveys. The study described here contributes to the hydrological assessment, focusing on a coastal lagoon called Karagan Lewaya and its small catchment area in the south of the development area. The lagoon will receive high quantities of drainage flows, which could deteriorate its quality as a habitat for migratory birds and lead to flooding of settlements. With the objective of improving the understanding of the hydrological dynamics and forecasting the impact of irrigation development, a simulation model was set up. Applying a simple spreadsheet modeling approach, a model of the lagoon was developed and combined with an adapted existing runoff model of the catchment area. The water balance model generates simulated lagoon water levels; a simulation of salinity levels was also attempted. Various scenarios concerning irrigation and lagoon management were defined. In order to collect data for the development and improvement of the models and to be able to monitor the future changes, the previously established hydrometric monitoring network was extended. Additional information was obtained from topographical maps and remote sensing images. Resulting from the lack of long data series needed for a calibration of the model, the simulation results remain preliminary. It was possible, however, to investigate the effects of different scenarios and to show general trends: Drainage flows from the extended irrigation scheme will lead to a significant rise of water level and decrease of salinity in the lagoon, with less fluctuations than at present. To prevent flooding of town areas close to the lagoon, an existing outlet channel will have to be opened during long periods. These changes will lead to a deterioration of the quality of Karagan Lewaya as a habitat for birds, but could be of benefit for the local settlers (washing, fishing, cattle bathing). en
dc.format Text en
dc.format.extent 1 digital file (75 p. : ill.) en
dc.format.mimetype Application/pdf
dc.language.iso en
dc.publisher University of Agricultural Sciences en
dc.subject LAND USE en
dc.subject ECOSYSTEMS en
dc.subject AGROECOLOGY en
dc.subject WATER MANAGEMENT en
dc.subject SALINATION en
dc.subject SIMULATION en
dc.subject GROUNDWATER en
dc.subject WATER QUALITY en
dc.subject WETLANDS en
dc.subject HYDROLOGY en
dc.title Estimating irrigation-induced changes of water and salinity levels in Karagan Lewaya lagoon, Sri Lanka en
dc.type Thesis en
idrc.project.number 100107
idrc.project.title Agro-ecosystem Management for Human Health in Uda Walawe Irrigation Scheme (Sri Lanka) en
idrc.dspace.access Limited Access en
idrc.rims.adhocgroup IDRC SUPPORTED en

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