Assessments of river condition are needed to guide all aspects of river management. Such assessments have evolved over three decades from simply capturing the mosaic of river physical habitats to ...recognizing that habitat mosaics are dynamic, driven mainly by physical processes and modified by human (indirect) pressures and (direct) interventions. To embrace these broader aspects, riparian as well as in‐stream environments need to be evaluated, going beyond subjective assessments to incorporate observations that support understanding of both physical habitat structure and cause‐effect relationships. This paper reports on an operational approach to assessing the physical condition of rivers, which attempts to bridge the gap between a physical habitat and a geomorphic condition assessment. The approach forms part of Biodiversity Metric 2.0, a habitat‐based methodology for measuring and accounting for biodiversity losses and gains resulting from development or land management change at individual project sites across England. The river condition assessment component adopts a bottom‐up multi‐scale approach that integrates field observations of physical habitats and of features indicative of geomorphic processes to deliver assessments of longer subreaches, whose condition is then evaluated within the context of the reach‐scale geomorphological type of river. By applying the assessment before, immediately after, and following recovery from project implementation, changes in condition and their causes can be evaluated. The assessment method is presented to an international audience, outlining its structure, application and testing, and critically discussing its strengths and weaknesses, because the methodological approach could be helpful for devising methods for application in other environmental contexts.
•The study explores the overall status of the Turag River using water quality index and river habitat survey.•All of the water quality parameters are within the standards except turbidity and DO.•The ...WQI reveals that the water quality in most of the locations is poor.•The conducted RHS indicates a poor habitat condition due to different human interventions.
River water quality in rapidly urbanizing Dhaka city threatens to achieve UN Sustainable Goals. Particularly, the Turag River, flowing along the periphery of the Dhaka megacity, is one of the most polluted rivers in the world. The accelerated economic growth based on industrialization, rapid urban expansion and population growth in this megacity pose numerous threats to the health of the Turag River. Therefore, the study aimed to conduct an eco-environmental assessment using Water Quality Index (WQI) and River Habitat Survey (RHS) to determine the physical, chemical and biological status of the Turag River. The study revealed that most of the water quality parameters i.e. pH, electrical conductivity (EC), salinity, total dissolved solids (TDS), major cations and anions were within the national and international (WHO) standards. Turbidity exceeded the desirable limit in all locations whereas, dissolved oxygen (DO) levels in 100% and 30% locations were below the standard for human consumption and sustaining aquatic community respectively. The calculated WQI confirmed that the water quality in most of the locations was poor due to intensive urbanization and industrialization though comparatively good water quality was evident in upstream. Thereby, the study ascertained that the water was not suitable for human consumption. The RHS indicated a poor habitat condition in the Turag River due to human interventions such as intensive channel modification, river encroachment, discharge of municipal and industrial sewage, etc. The findings of our study could be useful to develop urban river management plan to support sustainable river restoration.
Stream geodiversity is a novel concept that is used to describe the variety of geological, geomorphological and hydrological features at a reach‐scale level. In this study, we investigated the ...relationship between geodiversity and ecological indicators based on fishes, benthic macroinvertebrates and diatoms used for the ecological classification of rivers in line with the Water Framework Directive (WFD) 2000/60/EC. We examined whether geodiversity can be used as a proxy indicator of ecological quality, and we further tested if geodiversity can explain a significant amount of taxa richness variation. We hypothesized that undisturbed or minimally disturbed rivers will be more hydrologically and geomorphologically diverse, and as such, the ecological quality of streams will improve with geodiversity. We also attempted to quantify the probability of achieving ‘good’ ecological quality in relation to geodiversity levels through ordinal regression analysis. Although we did not find a significant relationship between geodiversity and taxonomic richness for any of the three freshwater groups, our results showed positive effects of geodiversity on all three ecological indicators. We also found that the likelihood of achieving the WFD target increases significantly with higher geodiversity. Our findings indicate that geodiversity can potentially serve as a proxy of ecological quality and highlight the need to consider the inclusion of geodiversity measures in ecological quality assessment systems.
In river landscapes subject to prolonged and high population pressure, the impact of human actions is usually so pervasive that re‐establishment of ‘natural’ river conditions is not possible. ...However, understanding the impacts of humans on river ecosystems is essential to identify how degradation of condition may be slowed or reversed and may also lead to the recognition that some human activities may be crucial for maintaining highly valued and sensitive river ecosystems. To achieve the necessary understanding for such judgements, it is essential to assemble, synthesize and analyse information on human actions, river environments and their interactions. In this paper, we focus on three commonly available information sources (historical records/archives, topographic and geomorphological maps, river habitat surveys) that can deliver relevant information over three timescales (centuries, decades, years). We illustrate the potential of these three data sources to assemble thematic and quantitative knowledge about how river systems function under a history of different human pressures and interventions, by exploring an example river landscape: the New Forest, southern England. We use this illustrative example for three reasons. First, for more than 1000 years, the New Forest has been affected by a complex range of land use and management practices which have heavily influenced the contemporary river landscape. Second, many of these human actions have degraded the landscape but others sustain highly valued landscape characteristics and ecosystems. Understanding the relative negative and positive impacts of different human actions is essential to understanding any river landscape with a long history of human use, and thus to designing balanced and appropriate management approaches. Third, in this special issue in memory of Professor Ken Gregory, we focus on an example landscape where he conducted research, allowing us to incorporate insights and data from his observations.
In river landscapes affected by prolonged human occupation, the impact of human actions is usually so pervasive that re‐establishment of ‘natural’ river conditions is impossible. We show how three commonly‐available information sources can deliver complementary information on river characteristics and management. We illustrate how understanding the impacts of humans on river ecosystems is essential to identify how degradation of river condition may be slowed or reversed, and how some human activities may be crucial for maintaining highly valued river ecosystems.
Riparian zones play an important role in the ecological stability of rivers. In particular, the quality of the riparian vegetation is a significant component of the hydromorphological status. In ...Europe, the QBR index (Qualitat del Bosc de Ribera) and the River Habitat Survey (RHS) are commonly used for the qualitative assessment of the riparian vegetation. In this study, we estimated the QBR index and the Riparian Quality index, which is derived from the RHS method, for 123 river reaches of the National Monitoring Network of Greece. Our field work included the completion of RHS and QBR protocols, as well as the use of Unmanned Aerial Vehicles (UAVs). The aim of this study is to assess the riparian vegetation status and to identify linkages with the dominant land uses within the catchment. Correlation analysis was used to identify the relationships between hydromorphological alterations and the degradation of the riparian vegetation, as well as their connection to land uses in the catchment area. Our results highlighted severe modifications of the riparian vegetation for the majority of the studied reaches. We also showed a differentiation of the QBR with respect to changes in the altitude and the land uses in the catchment area. Overall QBR reflects the variation in the riparian vegetation quality better than RQI. Our findings constitute an assessment of the status of the riparian zones in Greek rivers and set the basis for further research for the development of new and effective tools for a rapid quality assessment of the riparian zones.
•Maps of habitat distribution are needed to achieve environmental targets.•Existing monitoring data can be used to predict habitats using geostatistics.•A map of channel substrate is produced for all ...English and Welsh rivers.
Freshwater ecosystems are declining faster than their terrestrial and marine counterparts because of physical pressures on habitats. European legislation requires member states to achieve ecological targets through the effective management of freshwater habitats. Maps of habitats across river networks would help diagnose environmental problems and plan for the delivery of improvement work. Existing habitat mapping methods are generally time consuming, require experts and are expensive to implement. Surveys based on sampling are cheaper but provide patchy representations of habitat distribution. In this study, we present a method for mapping habitat indices across networks using semi-quantitative data and a geostatistical technique called regression kriging. The method consists of the derivation of habitat indices using multivariate statistical techniques that are regressed on map-based covariates such as altitude, slope and geology. Regression kriging combines the Generalised Least Squares (GLS) regression technique with a spatial analysis of model residuals. Predictions from the GLS model are ‘corrected’ using weighted averages of model residuals following an analysis of spatial correlation. The method was applied to channel substrate data from the River Habitat Survey in Great Britain. A Channel Substrate Index (CSI) was derived using Correspondence Analysis and predicted using regression kriging. The model explained 74% of the main sample variability and 64% in a test sample. The model was applied to the English and Welsh river network and a map of CSI was produced. The proposed approach demonstrates how existing national monitoring data and geostatistical techniques can be used to produce continuous maps of habitat indices at the national scale.
The paper presents the classification of the hydromorphological condition of the Breń River according to the River Habitat Survey (RHS). The research of the hydromorphological assessment of the Breń ...River, which is a right-bank tributary of the Vistula River and almost entirely flows through the area of the Dąbrowa Tarnowska district was conducted in June 2015. The research sites were situated on the border of the Tarnów Plateau and the Vistula Lowland. The Breń River in these sections flows through rural areas used for agricultural purposes with low-density housing. The analysis of qualitative parameters describing the morphological characteristics were based on two synthetic indices of stream quality: Habitat Quality Assesment (
) and Habitat Modification Score (
). The calculated numerical values of the two indices proved that the sections of the Breń River correspond with the third and fifth class, which means a moderate (III) and very bad (V) hydromorphological condition.
Fine sediment inputs from agricultural sources are a potential threat to freshwater ecosystems and may impact on the ability of EU members⿿ states to achieve environmental targets under the Water ...Framework Directive (WFD).
An index (the Agricultural Sediment Risk index or ASR) representing the risk of agricultural fine sediment accumulation in rivers was produced using estimates of sediment inputs from the process-based PSYCHIC model and predictions of fine sediment accumulation using River Habitat Survey data. The ASR was mapped across the entire river network of England and Wales.
The ASR map and index were combined with a national dataset of fisheries surveys using logistic regression to test its relevance to freshwater biota. The ASR was strongly associated with a group of species sensitive to fine sediment inputs including salmon and trout. Another group of species including roach and perch showed a positive association with low levels of agricultural sediment inputs potentially due to their impacts on predators and competitors.
The proposed approach demonstrates how existing national monitoring data and sediment pressure models can be combined to produce an assessment of risk to aquatic ecosystems from agricultural fine sediment sources at a national scale that can be used alongside WFD classification tools to identify potential causative pressures and design remedial actions.
The ecological assessment of all surface water bodies in Europe according to the Water Framework Directive involves the monitoring of biological, physicochemical and hydromorphological quality ...elements. For the hydromorphological assessment in particular, there are numerous methods that have been developed and adopted by EU member countries. With this study, we compared three different methods (River Habitat Survey, Morphological Quality Index and River Hydromorphology Assessment Technique) applied in 122 river reaches that are part of the National Monitoring Network of Greece. The main objectives were (a) to identify whether different assessment systems provide similar classifications of hydromorphological status and (b) to distinguish strengths and weaknesses associated with the implementation of each method. Our results show that the River Hydromorphology Assessment Technique (RHAT) and the Morphological Quality Index (MQI) resulted in the same classification for 58% of the studied reaches, while 34% of the remaining cases differed by only one quality class. Correlations between the two indices per river type (ICT) showed that the two indices were strongly correlated for water courses located at low altitudes. Concerning the HMS index of the River Habitat Survey (RHS), which is an index that reflects the overall hydromorphological pressure, it showed larger differences with the other two indices, mainly because it classified more sites as “Poor” and “Bad” quality classes. Based on our results, we recommend that the two indices, RHAT and MQI, can be implemented complementary to the RHS for providing a rather easy and quick assessment of the overall hydromorphological status, at least until a national hydromorphological database is compiled that will allow for the proper adaptation of the Habitat Quality Assessment (HQA) index.
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