| || || Lata, Sunita Ragni|
| || || Association of urban and terrestrial runoff to the water quality in the lower Sigatoka River Catchment, Viti Levu, Fiji |
Author:Lata, Sunita Ragni
Institution: University of the South Pacific.
Subject: Water quality -- Fiji -- Sigatoka River Watershed, Urban runoff -- Fiji -- Sigatoka River Watershed, Runoff -- Fiji -- Sigatoka River Watershed, Sigatoka River Watershed (Fiji)
Call No.: pac TD 370 .L382 2014
Copyright:20-40% of this thesis may be copied without the authors written permission
Abstract: The Coral Coast of Viti Levu, one of Fiji’s most intensely disturbed and populated coastlines (Thaman & Aalbersberg 2004; Rowlands et al 2005) has been the subject of water quality and integrated coastal management studies. These studies suggest that terrestrial runoff from disturbed catchments and other developments are causing widespread ecological change and degradation of the near shore marine environment (Mosley & Aalbersberg 2003; NIWA Client Report, 2004). Whilst point source impacts are increasingly understood (e.g. Naidu et al. 1997) diffuse source impacts are not. This study aims to locate and identify the source of diffuse impacts as a result of catchment disturbance. The quality of water in the tributaries of Lower Sigatoka River Catchment (LSRC) was noted and its potential association with the different land use within the Catchment is discussed. A total of 7 sites were selected from within the LSRC, which were chosen to represent 5 main land use types: undisturbed forest, traditional village, intensive agricultural, low impact traditional agricultural and urban. The water quality associated with different land use types was studied by carrying out field surveys for 13 consecutive months. Sampling was done at monthly intervals in an attempt to capture the different water quality parameters and flow regimes associated with different climatic conditions. Based on previous studies done by Carpenter and Lawedrau (2002) in the Rewa River catchment seasonal differences were expected. However the quality of water within the LSRC was not expected to mimic the water quality found in any other catchment in Fiji. The Sigatoka River Catchment has a unique physiography and is subject to a very different climatic environment compared to the Rewa River iii Catchment. Water quality parameters: nitrate, ammonia and phosphate concentrations; bacteria counts (E. coli and Salmonella); and physical parameters including turbidity, biological oxygen demand, flow rate (volume), chlorophyll concentrations and total suspended solids were measured at each catchment tributary during every field visit. Nutrients and other water quality parameters recorded in this study should be treated as baseline values for freshwater quality studies within the Sigatoka River Catchment. There is a lack of studies being conducted in the Sigatoka River catchment making it difficult to gauge any significant changes to water quality over time. The use of international guides for water quality comparison purposes would not be ideal in this case due to different catchments having different characteristics being subjected to different climatic conditions and disturbances and having different ecological significance attached to them. The quality of water within the LSRC is considered to be reasonable relative to its size, characteristics and development rate. From this study it was found that there is a link (association) between terrestrial activities and water quality within the catchment. Water quality parameters in the LSRC were affected by time sampling before and after rainfall events, water extraction, infiltration, water uptake by vegetation and land cover drainage patterns. From the results obtained it is noticed that there is a need for better catchment management practices for the LSRC. Agricultural activities, building infrastructure and waste disposal methods should be reviewed by the relevant authorities to allow improved management systems for increased conservation and sustainability of natural resources. iv It should be noted that this study forms the basis for future studies in the Sigatoka River Catchment.