Summary

River systems are important in providing vital water resource for humans and for ecosystem functions, but are increasingly affected by anthropogenic activities. The river health assessment programmes of Sri Lanka are largely based on water quality monitoring programmes, whereas the use of physical habitat quality assessment and tools such as bioindicators of water quality is largely unexplored. The incorporation of diverse attributes in conjunction with chemical water quality assessments provide better estimates of catchment impacts and thus the status of river health.
The first comprehensive study to evaluate the effectiveness of multiple attributes to measure river health in response to catchment land use impacts operating under different spatial scales was carried out in the Upper Mahaweli Basin in
Sri Lanka by the authors (Funded by NRC grant No: 13-160). The findings of this study laid the foundation for developing multiple attributes such as macroinvertebrate indices, stream physical attributes and riparian quality attributes in conjunction with water quality to measure catchment land use impacts on river health assessment programmes in Sri Lanka. The proposed study is aimed at evaluating the responsiveness of diverse stream health
assessment tools to multiple stresses arising from land-use practices in the Walawe River basin. The finding of this study is useful in developing monitoring tools for measuring the ecological integrity of rivers.

Objectives

To evaluate the effect of catchment land-use activities on water quality under different spatial scales. To evaluate nutrient dynamics and sources of contaminants of pollutants of river water using POC (POC%) and PON (PON%), and C/N ratio and isotopes (δ13C and δ15N).
To inventerise the macroinvertebrate taxa in selected reaches, and evaluation of their response to water quality changes specifically nutrient enrichment and salinization.
Assessment of responsiveness bioindicator tools such as Index of Biotic Integrity (IBI) to river health status of the Walawe River.

Major Equipment Facilitated by Grant