Projecting Land Use Transitions in the Gin Catchment, Sri Lanka

Wickramaarachchi, T. N.; Ishidaira, Hiroshi; Wijayaratna, Nimal

doi:10.19026/rjees.5.5677

Cited by 11 publications

(11 citation statements)

References 8 publications

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“…The catchment is located approximately between longitudes 80°08" E and 80°40" E, and latitudes 6°04" N and 6°30" N and includes Galle (83% of the basin area), Matara (9% of the basin area), Rathnapura (7% of the basin area), and Kalutara (1% of the basin area) administrative districts. The catchment's land is primarily used for human settlements, agriculture, natural forests and plantation forests [11]. Rainfall pattern in the catchment is of bi-modal, falling between May and September (Southwest monsoon, which is the major rainfall season), and again between November and February (Northeast monsoon) followed by the intermonsoon rains during the remaining months of the year.…”

Section: Study Areamentioning

confidence: 99%

“…Gin river caters approximately 90 % of the drinking water to Galle, the capital city in Southern Sri Lanka. Human activities in the Gin river basin have increased substantially in the past few decades including alterations in landuse pattern; subsequent to the expansion of homesteads, cultivated area in the basin has been decreased by 10% between early 80s and late 90s [11]. These activities have been causing significant impacts on the quality and clarity of water in the river creating a need to monitor the quality of water.…”

Section: Introductionmentioning

confidence: 99%

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Streamflow, Suspended Solids, and Turbidity Characteristics of the Gin River, Sri Lanka

2013

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Human induced impacts on the river systems result in decrease in water quality, which is generally reflected by an increase of particulate matter in rivers. Turbidity and suspended solids are part of physical and aesthetic parameters and good indicators of other pollutants that are carried as sediment in suspension. Study objectives were to define the relation between turbidity and total suspended solid (TSS) concentration in Gin river at Baddegama (6°11'23" N, 80°11'53" E) in developing an estimation technique for TSS load, and to reveal how turbidity and TSS load vary with the streamflow. Linear regression model developed between turbidity and TSS concentration showed strong positive correlation (R 2 = 0.98). Results strongly suggest turbidity is a suitable monitoring parameter for TSS, where TSS evaluation is crucial when logistical and financial constraints make TSS sampling impractical. Mean daily TSS loads in the Gin river at Baddegama during 2000-2009 were modeled in the study using load-discharge rating curve for estimating constituent loads in rivers. Relatively strong relationship (R 2 = 0.85) was observed between the rating curve estimated and observed TSS loads. Estimated TSS loads were having substantial temporal variation and generally peaked in May and October, coinciding with the high flows. Turbidity which ranged between 2.3 NTU (Nephelometric Turbidity Units) and 195 NTU significantly exceeded the maximum permissible limits of the water quality standards set for the potable water as well the inland waters of Sri Lanka. Since there was no specific water quality standards developed for TSS in Sri Lanka to compare with the present values, TSS concentrations were compared with the permissible total solid levels. TSS concentrations which ranged between 2.4 mg/l and 204 mg/l were well below the maximum permissible total solid level cited in the Sri Lanka standards for potable water. Understanding on this turbidity and TSS characteristics in Gin river flow might be useful for water managers and planners to adjust operations accordingly at water treatment plants.

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Section: Study Areamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Streamflow, Suspended Solids, and Turbidity Characteristics of the Gin River, Sri Lanka

2013

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“…Gin River is the most important water source to cover the drinking water supply requirement in the Galle district in Southern Sri Lanka. Recent studies exhibited degradation trend of water quality in Gin River as well significant change in land use in Gin catchment [8,9]. Lack of previous impact studies to assess similar environmental changes in humid tropical catchments including the Gin catchment makes this modelling effort important.…”

Section: Engineermentioning

confidence: 99%

“…This principally reflects the rapid expansion of homestead/garden to keep pace with population growth. According to Wickramaarachchi et al [9], Gin catchment"s land use change can be summarized over the past thirty years as a result of change in agricultural practices and increase in population. Moreover, the land use change trends projected in this study are consistent with the changing trends in homestead/garden and cultivated areas between early 80"s and mid 90"s, in Galle, as presented in the ADB report[17].…”

Section: Probability Mapsmentioning

confidence: 99%

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Projecting turbidity levels in future river flow: a mathematical modeling approach

et al. 2015

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Climate and land use change impacts on river flow were evaluated in this study with emphasis placed on turbidity. Turbidity levels for the year 2020 were projected for Gin River, one of the prime sources of drinking water in Southern Sri Lanka. Future land use in the Gin catchment was predicted using a GIS based statistical regression approach. Regional Climate Modelling system generated the future rainfall for the SRES A2 and SRES A1B emission scenarios. Streamflow simulations were carried out using a distributed hydrologic model, and turbidity values were determined using rating curve based relationship developed between river discharge and TSS (Total Suspended Solid) concentration followed by Turbidity-TSS linear regression correlation. Increased turbidity levels are clearly evident under the SRES A2 scenario, following more pronounced increased streamflows. Projected 75 th percentile monthly turbidity values in year 2020 are expected to increase during May to November compared to the baseline, andin certain months, about 100%increase is noted. 60% of the time, year 2020 turbidity levels have indicated exceedance of the water quality standards set for the potable water as well the inland waters of Sri Lanka, which would lead to exert extra challenge on future drinking water production in Southern region of Sri Lanka.

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Coupled hydrodynamic modelling approach to assess land use change induced flood characteristics

Jayapadma

Wickramaarachchi

Silva

et al. 2022

Environ Monit Assess

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Projecting Land Use Transitions in the Gin Catchment, Sri Lanka

Cited by 11 publications

References 8 publications

Streamflow, Suspended Solids, and Turbidity Characteristics of the Gin River, Sri Lanka

Streamflow, Suspended Solids, and Turbidity Characteristics of the Gin River, Sri Lanka

Projecting turbidity levels in future river flow: a mathematical modeling approach

Coupled hydrodynamic modelling approach to assess land use change induced flood characteristics

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