Distribution of an alien aquatic snail in relation to flow variability, human activities and water quality

1. Disturbance and anthropogenic land use changes are usually considered to be key factors facilitating biological invasions. However, specific comparisons of invasion success between sites affected to different degrees by these factors are rare.

2. In this study we related the large-scale distribution of the invading New Zealand mud snail (Potamopyrgus antipodarum) in southern Victorian streams, Australia, to anthropogenic land use, flow variability, water quality and distance from the site to the sea along the stream channel.

3. The presence of P. antipodarum was positively related to an index of flow-driven disturbance, the coefficient of variability of mean daily flows for the year prior to the study.

4. Furthermore, we found that the invader was more likely to occur at sites with multiple land uses in the catchment, in the forms of grazing, forestry and anthropogenic developments (e.g. towns and dams), compared with sites with low-impact activities in the catchment. However, this relationship was confounded by a higher likelihood of finding this snail in lowland sites close to the sea.

5. We conclude that P. antipodarum could potentially be found worldwide at sites with similar ecological characteristics. We hypothesise that its success as an invader may be related to an ability to quickly re-colonise denuded areas and that population abundances may respond to increased food resources. Disturbances could facilitate this invader by creating spaces for colonisation (e.g. a possible consequence of floods) or changing resource levels (e.g. increased nutrient levels in streams with intense human land use in their catchments).

Land use change and impacts on nutrient loads using GIS

Land use change and its impacts on nutrient loads were investigated for the Glenelg-Hopkins Catchment in south-west Victoria, Australia. The study involved a cross-disciplinary approach comprising of remote sensing, Geographical Information Systems, spatial and statistical modelling to identify relationships between land use and stream water quality over a large regional catchment of 27,000 square kilometers.

Integrative catchment modelling of land use, turbidity, flow and geology

The thesis outlines and demonstrates the various aspects that contribute towards water quality management systems and the important use of storage/water quality models. The application of models is demonstrated through the functions that modelling components have on sustainable regional development, and through linkage with water quality systems.

Land use, water quality and ecological responses in Lake Colac – trends from Australia

Purpose - Recently, Colac Otway Shire in Australia released its management plan for Lake Colac, claiming over-enrichment of the lake with nutrients and degraded water quality. This paper aims to investigate these claims by establishing a correlation between key water and ecological indicators and land uses.

Design/methodology/approach - Examines the correlation between impairment and stressors in Lake Colac. This was achieved by identifying the likely sources of pollutants into Lake Colac; identifying any existing monitoring program; and characterizing the water and sediment inputs. The likely impacts of increased nutrients and sediment levels on indigenous flora and fauna were also examined. The use of meiofauna (very small benthic metazoan animals) was investigated as an indicator of degraded sites. Plankton diversity as a measure of water health was also assessed.

Findings - Water quality in Lake Colac was found to vary both temporally and spatially, and exhibited low attainment against acceptable trigger values/objectives. At current levels the lake can be classified as poorly degraded. Likely sources of pollution were identified to be related to land uses in the catchments. The biota of the lake, investigated at four study sites, yielded a sparse, benthic macrofaunal assemblage that was dominated by oligochaetes. In contrast, an abundant and taxonomically diverse meiofaunal assemblage was noted. Future meiofaunal analyses are likely to resolve suitable biotic indicator species of free-living nematodes in response to land use and waterway threats specified in the study. Originality value - This work will provide a better understanding of integrated environmental systems to enable development of best management practices, thus transforming the way the land and water are used in the future. Following the present work, other key water and ecological indicators (increased dispersion and dominance of biological species) at five additional sites were studied. Alternative management options for the effluent generated at Colac Sewage Treatment Plant and possible ecological effects of each option were also evaluated. More recently, a sediment characterization study was also carried out at sensitive sites representative of locations where build up of sediments and algae outbreaks are reported. This will enable classification of sediment and evaluation of dredging options.

Mapping land use in a large agricultural basin : a comparison between classification techniques

In order to facilitate the better management of river basin resources, the Glenelg-Hopkins region in south-east Australia required an accurate and up to date land use map. Land use has a major impact on Australia's natural resources including its soil, water, flora and fauna and plays a major role in determining basin health. Inappropriate land use and practices have contributed to extensive dryland salinity and water quality problems. Land use data is often required for environmental models and in most cases the reliability of model outputs is dependent on the spatial detail and accuracy of the land use mapping. This paper examines methods to obtain an up to date land use map and a detailed accuracy assessment using Landsat ETM+ data for a regional basin. A multi-source based approach allowed the collection of 4817 ground truth data points from the field investigation. This enabled researchers to (i) incorporate a full range of information into digital image analysis with significant improvements in accuracy and (ii) hold sufficient independent references for an accurate error assessment. Classification accuracy was significantly improved using a stratification design, in which the region is sub-divided into smaller homogenous areas as opposed to a full scene classification technique. The overall classification accuracy was 84% (KHAT= 0.833) for the stratified approach compared to 76% (KHAT= 0.743) for the full scene classification. Effective assessment, planning and management of basins are dependent on a sound knowledge of the distribution and variability of land use.

Water, land use change and 'new forests': what are the challenges for South-Western Victoria?

Land use change has occurred rapidly in southwestern Victoria over the last decade and is expected to continue, albeit at a slower pace. One of these changes has been the development of 'new forests', that is industrial and farm forestry plantations and environmental plantings. Some of the challenges that these land use changes pose for water and natural resource managers are discussed. Land use change is expected to substantially reduce potential water yield in four of the region's seven drainage basins (A).

Regional-scale models for relating land cover to basin surface-water quality using remotely sensed data in a GIS

Plant-based management systems implementing deep-rooted, perennial vegetation have been identified as important in mitigating the spread of secondary dryland salinity due to its capacity to influence water table depth. The Glenelg Hopkins catchment is a highly modified watershed in the southwest region of Victoria, where dryland salinity management has been identified as a priority. Empirical relationships between the proportion of native vegetation and in-stream salinity were examined in the Glenelg Hopkins catchment using a linear regression approach. Whilst investigations of these relationships are not unique, this is the first comprehensive attempt to establish a link between land use and in-stream salinity in the study area. The results indicate that higher percentage land cover with native vegetation was negatively correlated with elevated in-stream salinity. This inverse correlation was consistent across the 3 years examined (1980, 1995, and 2002). Recognising the potential for erroneously inferring causal relationships, the methodology outlined here was both a time and cost-effective tool to inform management strategies at a regional scale, particularly in areas where processes may be operating at scales not easily addressed with on-site studies.

Assessment of spatiotemporal varying relationships between rainfall, land cover and surface water area using geographically weighted regression

Traditional regression techniques such as ordinary least squares (OLS) are often unable to accurately model spatially varying data and may ignore or hide local variations in model coefficients. A relatively new technique, geographically weighted regression (GWR) has been shown to greatly improve model performance compared to OLS in terms of higher R 2 and lower corrected Akaike information criterion (AICC). GWR models have the potential to improve reliabilities of the identified relationships by reducing spatial autocorrelations and by accounting for local variations and spatial non-stationarity between dependent and independent variables. In this study, GWR was used to examine the relationship between land cover, rainfall and surface water habitat in 149 sub-catchments in a predominately agricultural region covering 2.6 million ha in southeast Australia. The application of the GWR models revealed that the relationships between land cover, rainfall and surface water habitat display significant spatial non-stationarity. GWR showed improvements over analogous OLS models in terms of higher R 2 and lower AICC. The increased explanatory power of GWR was confirmed by the results of an approximate likelihood ratio test, which showed statistically significant improvements over analogous OLS models. The models suggest that the amount of surface water area in the landscape is related to anthropogenic drainage practices enhancing runoff to facilitate intensive agriculture and increased plantation forestry. However, with some key variables not present in our analysis, the strength of this relationship could not be qualified. GWR techniques have the potential to serve as a useful tool for environmental research and management across a broad range of scales for the investigation of spatially varying relationships.

Sensor placement and measurement of wind for water quality studies in urban reservoirs

We study the water quality in an urban district, where the surface wind distribution is an essential input but undergoes high spatial and temporal variations due to the impact of surrounding buildings. In this work, we develop an optimal sensor placement scheme to measure the wind distribution over a large urban reservoir using a limited number of wind sensors. Unlike existing solutions that assume Gaussian process of target phenomena, this study measures the wind that inherently exhibits strong non-Gaussian yearly distribution. By leveraging the local monsoon characteristics of wind, we segment a year into different monsoon seasons that follow a unique distribution respectively. We also use computational fluid dynamics to learn the spatial correlation of wind. The output of sensor placement is a set of the most informative locations to deploy the wind sensors, based on the readings of which we can accurately predict the wind over the entire reservoir in real time. Ten wind sensors are deployed. The in-field measurement results of more than 3 months suggest that the proposed sensor placement and spatial prediction scheme provides accurate wind measurement that outperforms the state-of-the-art Gaussian model based on interpolation-based approaches.

Unhealthy landscapes: policy recommendations on land use change and infectious disease emergence

Anthropogenic land use changes drive a range of infectious disease outbreaks and emergence events and modify the transmission of endemic infections. These drivers include agricultural encroachment, deforestation, road construction, dam building, irrigation, wetland modification, mining, the concentration or expansion of urban environments, coastal zone degradation, and other activities. These changes in turn cause a cascade of factors that exacerbate infectious disease emergence, such as forest fragmentation, disease introduction, pollution, poverty, and human migration. The Working Group on Land Use Change and Disease Emergence grew out of a special colloquium that convened international experts in infectious diseases, ecology, and environmental health to assess the current state of knowledge and to develop recommendations for addressing these environmental health challenges. The group established a systems model approach and priority lists of infectious diseases affected by ecologic degradation. Policy-relevant levels of the model include specific health risk factors, landscape or habitat change, and institutional (economic and behavioral) levels. The group recommended creating Centers of Excellence in Ecology and Health Research and Training, based at regional universities and/or research institutes with close links to the surrounding communities. The centers' objectives would be 3-fold: a) to provide information to local communities about the links between environmental change and public health ; b) to facilitate fully interdisciplinary research from a variety of natural, social, and health sciences and train professionals who can conduct interdisciplinary research ; and c) to engage in science-based communication and assessment for policy making toward sustainable health and ecosystems.

Land use change and nutrients simulation for the Siah Darvishan basin of the Anzali wetland region, Iran

The Anzali Ramsar Convention wetland is located in an ecologically and economically important region in Iran. The wetland is largely surrounded by agriculture, natural forests and rangelands (approximately 36% and 63%, respectively). Urban areas consist of less than 1% of the total area. Urban land use produces the highest rates of nutrient transfer into the lake as TN, TP and BOD5 equal to 24, 2.4 and 79 Kg/ha/year, respectively, whilst, natural land use produces the lowest rate as 10, 1.3 and 27 kg/ha/year. These results will inform the future sustainable management of this important wetland in this ever increasingly water stressed region in Iran.

Preserving the environment and traditional communities : a land use change modeling approach

Human populations can cause serious damage to the natural environment. This, however, depends on the type of society and its size. Many traditional communities have a balanced relation with the environment, using practices for managing the soil, water and natural resources in order to satisfy their needs that are compatible to the general goals of environmental preservation.

The most usual approach to environmental conservation in the world sees human beings as intruders, potentially destroyers of the nature and, as a consequence, generally requires local population to be expelled from the protected regions. This situation has generated social conflicts because many protected areas, particularly in developing countries, are inhabited by indigenous or other traditional communities.

The disagreement about expelling or maintaining traditional communities in environmental conservation areas is strengthened by the lack of diagnostics on which changes are produced or suffered by communities in the region where they live. This paper presents a methodology developed to analyse land use dynamics in region with environmental conservation and traditional communities. We seek a better understanding of the way traditional communities use their space, the spatial pattern of land uses, which factors drive land use change, which impacts can be seen in those regions and identify the effects of conservation policies on land use dynamics.

The application of the method to the National Park of Superagui, Brazil, has successfully performed characterisation, analysis and simulation of land use dynamics in a region of environmental importance. Testing different scenarios has suggested that the adoption of a less restrictive policy for environmental conservation would have resulted in less social conflict with the same environmental efficiency than the established current policy.