Uthpala Pinto

River health assessment in peri-urban landscapes: An application of multivariate analysis to identify the key variables

An array of river health assessment approaches and water quality variables have been suggested in the past for assessing the level of river health. However, the selection of suitable variables to be monitored for the assessment remains ambiguous and often it is not practical to monitor all the suggested variables. In this study, we employ a multivariate data reduction technique, called Factor Analysis (FA), to identify the key river health variables for a peri-urban river system, viz., the Hawkesbury-Nepean River system in New South Wales, Australia. Out of 40 water quality variables included in the analysis, the FA identified nine key variables, under three varifactors (VFs), explaining 50% of the variance in the river water quality. Variables in the first, second and third VFs revealed anaerobic conditions, microbial quality and effects of eutrophication in the Hawkesbury-Nepean River. Thus, the present work shows a notable reduction in the number of variables and the application of FA for identification of key variables was found promising. The finding of this study has potential application in designing a cost-effective river health monitoring program by reducing the number of variables to be monitored in a peri-urban situation. It can also assist in partitioning variables according to their unique contribution to the total variance.

Reuse of greywater for irrigation around homes in Australia : understanding community views, issues and practices

We examined peoples views on a number of water issues and their motivation, practices and concerns about greywater reuse for irrigation of around homes. Survey participants (275) from different socio-economic background from 125 suburbs in the Western Sydney region, Australia took part in the study. Regardless of their age and gender, when asked which was the most important issue regarding water in their region from a prescribed list, the majority of participants identified water quality as the most important and availability without water restriction as the least important. About half of the participants reused greywater regularly or at some time during the last few years. The cost of plumbing and health risks to people, plants and soil are critical issues for greywater reuse and need attention. For the reusing widely and sustainably, there is a need for easily accessible, user-friendly information packages to create ‘greywater reuse literacy’ in the community.

Modelling eutrophication and microbial risks in peri-urban river systems using discriminant function analysis

The methodology currently available to river managers for assessment of river conditions for eutrophication and microbial risks is often time consuming and costly. There is a need for efficient predictive tools based on easily measured variables for implementing appropriate management strategies and providing advice to local river users on river health and associated risks. Using the Hawkesbury-Nepean River system in New South Wales, Australia as case study, a stepwise discriminant function analysis was employed to develop two predictive models, one for river eutrophication risk and the other for microbial risk. The models are intended for a preliminary assessment of a river reach, particularly to assess the level of risk (high or low) for algal bloom and whether the river water is suitable for primary contact activities such as swimming. The input variables for both models included saturated dissolved oxygen and turbidity, while the eutrophication risk model included temperature as an additional variable. When validated with an independent data set, both models predicted the observed risk category accurately in two out of three instances. Since the models developed in this study use only two or three easy-to-measure variables, their application can help in rapid assessment of river conditions, result in potential cost saving in river monitoring programs and assist in providing timely advice to community and other users for a particular aspect of river use.

Impacts of Water Quality on the Harvest of School Prawn (Metapenaeus macleayi) in a Peri-Urban River System

ABSTRACT The school prawn (Metapenaeus macleayi) is important among commercial prawn trawler operators, but its harvest is affected in a complex way by a number of interacting water quality, and other variables. In this study, using the Hawkesbury—Nepean River system as a case study, we use Pearson correlation and hierarchical agglomerative cluster analysis (HACA) to assess the influence of the selected water quality (n = 7), quantity (n = 1), and weather (n = 2) parameters on the prawn harvest. Using data records (n = 104) collected over a 9-y period, we found water temperature (r = 0.63, P < 0.01), dissolved oxygen (r = -0.59, P < 0.01), and rainfall (r = 0.26, P < 0.01) to be significantly correlated variables with prawn harvest. The HACA produced 3 distinct clusters of variables nutrient availability for prawns (the total nitrogen, the total phosphorus, reactive silicate, turbidity, and suspended solids), the physical river environment (temperature, rainfall, and river flow), and the biochemical river environment (dissolved oxygen and chlorophyll a). The study revealed that 2 key variables, viz., temperature and rainfall, representing the physical river environment are statistically significant in affecting prawn harvest in the study area. Therefore, from fishing industry point of view, the future river management need to focus on strategies that will improve the physical river environment, particularly to cope with the impacts of future peri-urban development and climate change scenarios.

Sustainable graywater reuse for residential landscape irrigation – a critical review

The demand for potable water is rising rapidly due to an ever-increasing population, economic activities, and dwindling water supplies. To provide adequate water supplies in the future, understanding the issues and challenges in the reuse of water and developing appropriate strategies for reuse will be critical. One way to augment water supplies for residential use is to reuse graywater – the wastewater from kitchens, bathrooms, and laundries. In this article, we critically review the evolution of water reuse, the definition of graywater, graywater reuse practices, volumes and flow in different situations, and graywater characteristics. We then examine the issues associated with different graywater treatment methods and how using graywater for irrigation around homes affects soil quality and plant growth. The study concludes that graywater treatment costs, human health risks, and its effect on soil quality are some of the challenges that need to be addressed in the future for widespread and sustainable reuse of graywater for irrigation around homes.

Perspectives on impacts of water quality on agriculture and community well-being—a key informant study from Sri Lanka

Integrated management of water quality is critical for sustaining food production and achieving overall well-being of a community. Further, understanding people’s perceptions and engagement can play an important role in achieving water and food security. The main aim of this study was to investigate the perspectives of community and other stakeholders as to how water quality impacts on agriculture, livelihood and community well-being within rural farming communities of two dry zone districts of Sri Lanka. The study adopted ‘key informant interviews’ as the methodology to investigate community and other stakeholder perspectives to collect primary data over a period of four months. The interview contents were then examined using a frequency matrix and graphed using an Excel graphing tool. The raw text was also analysed to understand the broader patterns in the text. A fuzzy logic cognitive map (FCM) was developed using the relationships between various concepts and linkages provided by the key informants. All key informants were concerned with the quality of drinking water they consume and the water used for their food preparation. Key informants representing the farming community indicated that the use of poor quality groundwater with higher levels of hardness has made growing crops difficult in the region. The key informants also identified extensive and ongoing use of agro-chemicals and fertilisers as a major source of pollution in water bodies in both spatio-temporal scale. Based on key informant interviews, possible initiatives that can help improve surface water and groundwater qualities for both drinking and agricultural use in the dry zone of Sri Lanka can be categorised into four broader themes, viz., provision of filtering/treatment systems, reduction in the use of agro-chemical and fertilisers, education of community stakeholders and support of alternative options for portable water supplies. The study indicates that in the key informants’ view of groundwater and surface waters’ continued deterioration in the absence of a proper governance structure, a majority of farmers will have restricted access to good quality water to meet daily and agricultural needs, and this will affect the health of the elderly and children in the area. Further, a majority of key informants were of the view that management of surface water and groundwater should be a shared responsibility between the government and the community in the region and appropriate policy initiatives that will improve water literacy at all levels are mandatory to address future water quality challenges.

Development of Future Management Options for the Hawkesbury River

The Hawkesbury River is a valuable community asset. In the last 200 years there have been continuous and significant changes which have resulted in declining river health and impacts on community values. Management processes which purport to arrest this decline and provide protection or improvements to the quality of the Hawkesbury River were reviewed in light of community concerns and available water quality analysis data. Clear responses in waterway condition can be linked to catchment activities and some management processes to improve river health. It appears however, many such management practices have not been assessed or are not capable of assessment. The development of a framework to assess future management proposals for protection and remediation of the Hawkesbury River is proposed.