Novel river eco-hydrological systems projected for Europe

Future flows in rivers throughout Europe were computed for different combinations of climate models and socio-economic scenarios for a baseline (1961-1990) and for the future (2050s). Sets of indicators describing all ecologically-relevant facets of river flow regime were derived. Eco-hydrological regime types were defined using classification techniques applied to these indicators. Projected future flow alterations (2050s) for major European rivers were mapped in terms of eco-hydrological types and compared with maps for the baseline situation. It was found that for many river reaches their regime would remain broadly similar (in the same class), for other reaches the regime would alter to be more similar to another class. For some reaches the eco-hydrological regime would change to a novel form not currently seen in Europe, with the potential to create new river ecosystems

Classification of natural flow regimes in Iran to support environmental flow management

Development of environmental flow standards at the regional scale has been proposed as a means to manage the influence of hydrological alterations on riverine ecosystems in view of the rapid pace of global water resources management. Flow regime classification forms a critical part in such environmental flow assessments. We present a national-scale classification of hydrological regimes for Iran based on a set of hydrological metrics. It describes ecologically relevant characteristics of the natural hydrological regime derived from 15- to 47-year-long records of daily mean discharge data for 539 streamgauges within a 47-year period. The classification was undertaken using a fuzzy partitional method within Bayesian mixture modelling. The analysis resulted in 12 classes of distinctive flow regime types that differ in various hydrological aspects. This classification is being used for further research in regional-scale environmental flow studies in Iran

A simple model to quantify the potential trade-off between water level management for ecological benefit and flood risk

Throughout the world, historic drainage of wetlands has resulted in a reduction in the area of wet habitat and corresponding loss of wetland plant and animal species. In an attempt to reverse this trend, water level management in some drained areas is trying to replicate a more natural ‘undrained’ state. The resulting hydrological regime is likely to be more suitable to native wetland species; however the raised water levels also represent a potential reduction in flood water storage capacity. Quantifying this reduction is critical if the arguments for and against wetland restoration are to be discussed in a meaningful way. We present a simple model to quantify the hydrological storage capacity of a drainage ditch network under different water level management scenarios. The model was applied to the Somerset Levels and Moors, UK, comparing areas with and without raised water level management. The raised water level areas occupy 11% of the maximum theoretical storage but when put in the context of the recent severe flooding of winter 2013/2014 occupy only 0.6% of the total flood volume and represent an average increase in flood level of 7 mm. These results indicate that although the raised water level scheme does occupy an appreciable volume of the maximum possible ditch storage, in relation to a large flood event the volume is very small. It therefore seems unlikely that the severity of such large flood events would be significantly reduced if the current water level management for ecological benefit ceased

Hydroecological impacts of climate change modelled for a lowland UK wetland

Conservation management of wetlands often rests on modifying hydrological functions to establish or maintain desired flora and fauna. Hence the ability to predict the impacts of climate change is highly beneficial. Here, the physically based, distributed model MIKE SHE was used to simulate hydrology for the Lambourn Observatory at Boxford, UK. This comprises a 10 ha lowland riparian wetland protected for conservation, where the degree of variability in the peat, gravel and chalk geology has clouded hydrological understanding. Notably, a weathered layer on the chalk aquifer surface seals it from overlying deposits, yet is highly spatially heterogeneous. Long-term monitoring yielded observations of groundwater and surface water levels for model calibration and validation. Simulated results were consistent with observed data and reproduced the effects of seasonal fluctuations and in-channel macrophyte growth. The adjacent river and subsidiary channel were found to act as head boundaries, exerting a general control on water levels across the site. Discrete areas of groundwater upwellings caused raised water levels at distinct locations within the wetland. These were concurrent to regions where the weathered chalk layer is absent. To assess impacts of climate change, outputs from the UK Climate Projections 2009 ensemble of global climate models for the 2080s are used to obtain monthly percentage changes in climate variables. Changes in groundwater levels were taken from a regional model of the Chalk aquifer. Values of precipitation and evapotranspiration were seen to increase, whilst groundwater levels decreased, resulting in the greater dominance of precipitation. The discrete areas of groundwater upwelling were seen to diminish or disappear. Simulated water levels were linked to specific requirements of wetland plants using water table depth zone diagrams. Increasing depth of winter and summer groundwater levels leads to a loss of Glyceria maxima and Phragmites australis, principal habitat for the endangered Vertigo moulinsiana. Further, the reduced influx of base-rich groundwater and increased dominance of high pH rain-fed waters alters the acidity of the soil. This leads to changes in species composition, with potential reductions in Carex paniculata, Caltha palustris and Typha latifolia

Predicting physical habitat sensitivity to abstraction

A new version of the Rapid Assessment of Physical Habitat Sensitivity to Abstraction (RAPHSA) model was developed with a specific focus on operational applications. The original RAPHSA defined sensitivity to abstraction as the change in physical habitat with changes in river discharge. Several development needs were identified in order to deploy the model operationally, in particular: (1) Improving the representativeness of the calibration dataset - The original model was calibrated using a collection of PHABSIM studies totaling 516 transects at 64 river sites (ie stretches). This dataset is biased towards lowland permeable rivers. As a consequence, the geographical coverage and the river types captured by the model are limited. This issue was successfully resolved by analysing more than 4,000 potential additional sites in England and Wales with detailed hydraulic data, of which 90 were retained by applying a combination of criteria (eg proximity of gauging station, overlap of gauged flow and hydraulic data). (2) Simplifying the model - In order to standardise information across calibration sites, the original model uses flow percentile ranks, thus requiring the derivation of the flow duration curve prior to any run. The new version instead standardises with bankfull flow, which can be estimated from a single site hydraulic survey. In addition, fewer predictors are used. A Jackknifing procedure was run on both models, which performed very closely. The new RAPHSA has slightly higher mean squared errors, which is likely due to being calibrated on a wider range of river types than the original model

Projected novel eco-hydrological river types for Europe

Climate change and human use of water abstracted from rivers and groundwater are projected to alter river flow regimes worldwide in coming decades. Consequently, community structure in many rivers is expected to change because river flow is fundamental in determining conditions required by organisms, and processes on which they depend. Future flows in pan-European rivers were computed for baseline conditions (period 1961–1990) and for different combinations of climate and socio-economic scenarios (2040–2069). For each scenario a set of indicators was produced describing flow regime aspects that are most important in determining river ecosystem character. Classification techniques were applied to each set to define eco-hydrological river types. Spatial patterns of baseline and future types were mapped. Depending on scenario, about 30–50% of the river network length remained of the same type, whilst c. 40–50% transformed to an existing type; a third group of rivers (c. 10–20% of network length) formed new types, not present under baseline conditions, with potential to create novel river ecosystems

Managing rivers for multiple benefits – a coherent approach to research, policy and planning

Rivers provide water for irrigation, domestic supply, power generation and industry as well as a range of other ecosystem services and intrinsic and biodiversity values. Managing rivers to provide multiple benefits is therefore foundational to water security and other policy priorities. Because river flow is often insufficient to meet all needs fully, water management experts have acknowledged the need for trade-offs in river management. Ecosystem scientists have classified and quantified goods and services that rivers provide to society. However, they have seldom examined the way in which water management infrastructure and institutional arrangements harness and direct goods and services to different groups in society. Meanwhile, water management paradigms have often considered freshwater ecosystems as rival water users to society or a source of natural hazards and have underplayed the role healthy ecosystems play in providing multiple social and economic benefits. We argue that physical and social structures and processes are necessary to realize multiple benefits from river ecosystems, and that these structures and processes, in the form of (formal and informal) institutions and (gray and green) infrastructure, shape how benefits accrue to different groups in society. We contend that institutions and infrastructure are in turn shaped by political economy. We suggest a more coherent framework for river management research, policy and planning that focuses on (a) the ways in which political economy, institutions and infrastructure mediate access and entitlements to benefits derived from ecosystem services, and (b) the feedbacks and trade-offs between investments in physical and social structures and processes

Drought forecasting isn\u27t just about water- to get smart we need health and financial data too

The Millennium Drought taught Australians many lessons about living under extremely dry conditions – not just about how to conserve water, but also about human suffering. In a drought, farmers find it more difficult to make an income, leading to mental health problems and raising the rate of male suicides. In the city, the impact is felt through water restrictions and more expensive infrastructure. With very dry conditions returning to Tasmania, central Queensland and western Victoria, are we better prepared for the next big drought? This is an issue not just for Australia, but across the world, from California, to England, to the Levant region in the eastern Mediterranean, which from 1998-2012 experienced its worst drought in 900 years