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

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dc.contributor.authorStanzel, Philipp
dc.date.accessioned2015-08-10T19:05:28Z
dc.date.available2015-08-10T19:05:28Z
dc.date.issued2002-09
dc.descriptionThe 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 Acten
dc.description.abstractThe 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.formatTexten
dc.format.extent1 digital file (75 p. : ill.)en
dc.format.mimetypeApplication/pdf
dc.identifier.urihttp://hdl.handle.net/10625/54499
dc.language.isoen
dc.publisherUniversity of Agricultural Sciencesen
dc.subjectLAND USEen
dc.subjectECOSYSTEMSen
dc.subjectAGROECOLOGYen
dc.subjectWATER MANAGEMENTen
dc.subjectENVIRONMENTAL IMPACT ASSESSMENTen
dc.subjectIRRIGATION SYSTEMSen
dc.subjectSALINATIONen
dc.subjectSIMULATIONen
dc.subjectMATHEMATICAL MODELSen
dc.subjectGROUNDWATERen
dc.subjectWATER QUALITYen
dc.subjectWETLANDSen
dc.subjectHYDROLOGYen
dc.titleEstimating irrigation-induced changes of water and salinity levels in Karagan Lewaya lagoon, Sri Lankaen
dc.typeThesisen
idrc.dspace.accessLimited Accessen
idrc.project.number100107
idrc.project.titleAgro-ecosystem Management for Human Health in Uda Walawe Irrigation Scheme (Sri Lanka)en
idrc.rims.adhocgroupIDRC SUPPORTEDen

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