Towards better prediction of water quality in Ungauged Basins

This chapter discusses issues related to water quality prediction in Australia, where land and water resources are being adversely affected by the degradation of river basins by a range of land use practices. One such example is the impact of dryland and stream salinity arising from the large-scale clearing of native vegetation. Whilst there is now good understanding of the interrelationships between the human impact and water quality, sustainable management of land and water resources requires the development of predictive models for water quality, so that more reliable information can be provided to stakeholders for making responsible decisions. The end-member mixing analysis, i.e., spatial prediction of water quality and other water quality temporal prediction approaches are discussed. In addition, the mass balance approach, modelling stream water chemistry as a result of hillslope processes and the integration of water quality prediction approaches, are also discussed

Diachronic analysis of salt-Affected areas using remote sensing techniques: the case study of Biskra area, Algeria

In the Wadi Biskra arid and semi-arid area, sustainable development is limited by land degradation, such as secondary salinization of soils. As an important high quality date production region of Algeria, it needs continuous monitoring of desertification indicators, since the bio-physical setting defines it as highly exposed to climate-related risks. For this particular study, for which little ground truth data was possible to acquire, we set up an assessment of appropriate methods for the identification and change detection of salt-affected areas, involving image interpretation and processing techniques employing Landsat imagery. After a first phase consisting of a visual interpretation study of the land cover types, two automated classification approaches were proposed and applied for this specific study: decision tree classification and principal components analysis (PCA) of Knepper ratios. Five of the indices employed in the Decision Tree construction were set up within the current study, among which we propose a salinity index (SMI) for the extraction of highly saline areas. The results of the 1984 to 2014 diachronic analysis of salt - affected areas variation were supported by the interpreted land cover map for accuracy estimation. Connecting the outputs with auxiliary bio-physical and socio-economic data, comprehensive results are discussed, which were indispensable for the understanding of land degradation dynamics and vulnerability to desertification. One aspect that emerged was the fact that the expansion of agricultural land in the last three decades may have led and continue to contribute to a secondary salinization of soils. This study is part of the WADIS-MAR Demonstration Project, funded by the European Commission through the Sustainable Water Integrated Management (SWIM) Program (www.wadismar.eu)

Removal of volatile organic compounds (VOCs) from groundwater by reverse osmosis and nanofiltration

A comprehensive study was conducted to examine the removal of volatile organic compounds (VOCs) which exist in groundwater at Southlands-Botany Bay (Sydney region). The ability of nanofiltration (NF) and reverse osmosis (RO) as advanced treatments was investigated using two commercially available NF or RO membranes. Laboratory-scale tests were used with cross-flow; tests were conducted with 16 ubiquitous compounds that represented the significant volatile organic compounds found in the contaminated groundwater. The results reported in this study indicate that the removal efficiency of reverse osmosis (RO) was better than NF in rejecting the VOCs detected in groundwater. This study revealed that the performance of NF and RO membranes in rejecting hydrophilic volatile organic compounds was higher than that for hydrophobic compounds and the highest rejection achieved by NF and RO membranes amounted 98.4% and 100%, respectively. Hydrophilic compounds can be effectively rejected by NF/RO membranes using the size exclusion mechanism (steric hindrance), whereas hydrophobic compounds can be adsorbed into NF/RO membranes and then diffuse through the dense polymeric matrix, resulting in the lower removal for these compounds compared to hydrophilic compounds

Assessment of remote sensing-based classification methods for change detection of salt-affected areas (Biskra area, Algeria)

In the Wadi Biskra arid and semiarid areas, sustainable development is restricted by land degradation processes such as secondary salinization of soils. Being an important highquality date production region of Algeria, this area needs continuous monitoring of desertification indicators, hence highly exposed to climate-related risks. Given the limited access to field data, appropriate methods were assessed for the identification and change detection of salt-affected areas, involving image interpretation and automated classifications employing Landsat imagery, ancillary and multisource ground truth data. First, a visual photointerpretation study of the land cover and land use classes was undergone according to acknowledged methodologies. Second, two automated classification approaches were developed: a customized decision tree classification (DTC) and an unsupervised one applied to the principal components of Knepper ratios composite. Five indices were employed in the DTC construction, among which also is a salinity index. The diachronic analysis was undergone for the 1984 to 2015 images (including seasonal approach), being supported by the interpreted land cover/land use map for error estimation. Considering also biophysical and socioeconomic data, comprehensive results are discussed. One of the most important aspects that emerged was that the accelerated expansion of agricultural land in the last three decades has led and continues to contribute to a secondary salinization of soils

A methodology for the rapid assessment of the potential impact and hazard of coal seam gas mining on aquifers and the environment

The potential environmental impacts and hazards of coal seam gas mining in Australia are highly contentious and poorly understood. Concerns have been raised by communities, and the Australian government has incorporated management tools and strategies to address these concerns. The primary environmental issue associated with coal seam gas mining would be on the aquifers above the target coal seam. If the upper aquifers are affected in terms of quantity and quality, then there are cumulative impacts to the surface environment such as groundwater dependent ecosystems and surface waters. This paper will examine the Australian situation with regard to coal seam gas mining and present a methodology for rapid assessment of the potential impacts and hazards of coal seam gas extraction on aquifers and surface environments. A GIS analysis method for developing broad scale potential impact and hazard criterion for aquifers above the target coal zone are discussed. Current investigations and future research and development opportunities are explored

Overview of factors leading to dryland salinity and its potential hazard in New South Wales, Australia

A proposed new method for predicting the occurrence of dryland salinity is to 1) map current outbreaks of dryland salinity at a broad regional scale; 2) process the results of investigations at various scales of inquiry; and 3) develop predictive tools using Geographic Information Systems (GIS). In New South Wales, Australia, the clearing of native vegetation has led to increased groundwater recharge, with a subsequent rise of water tables, thereby resulting in dryland salinity. Areas where increased recharge was observed throughout the State correspond to broad areas of vegetation clearing. Relationships also exist between the occurrence of salinity and the interaction of particular land attributes and environmental features that result in groundwater levels approaching the land surface. The new tool for mapping dryland-salinity hazard is based on the relationship that exists between the occurrence of dryland salinity and particular combinations of land attributes. Dryland-salinity occurrence was mapped spatially and digitised into a GIS, and GIS analysis was conducted with a statistical technique called \u27weights of evidence.\u27 Using this tool, the relative degrees of salinity hazard of different areas were identified that would result if a disturbance to the water balance were to take place. The results are shown on salinity-hazard maps, which aid in prioritising areas for allocating resources and managing areas that display high hazard