Hydromorphological Assessment Research Articles

The impact of the geographical environment on the hydromorphological conditions of watercourses in southern Poland

Hydromorphological assessment of watercourses provides much valuable information about the riverbed and its immediate surroundings, including the influence of geographical environmental factors along with anthropogenic pressures in the catchment area. This paper presents diversity of hydromorphological conditions of 77 sections located on 39 watercourses in southern Poland in three European ecoregions: Eastern Plains, Central Plains and the Carpathians. The study was based on the Hydromorphological Index for Rivers (HIR) method and two sub-indices: Hydromorphological Diversity Score (HDS) and Hydromorphological Modification Score (HMS). Basic and multi-dimensional statistical analyses were performed to identify the main gradients of the geographical environment and the variables that contribute most to the total variability of HIR. The highest mean HIR values were recorded in the Carpathians ecoregion, then in the Central Plains and the lowest in the Eastern Plains, 0.70, 0.67 and 0.58, respectively. Significant differences were found between the Carpathians and Eastern Plains ecoregions in HIR values obtained. Hydromorphological differentiation is most influenced by altitude and geological type. The cluster analysis enabled two main groups of watercourses to be distinguished – the first one was dominated by variables showing HMS > HDS relationship, while the second one was dominated by HDS > HMS relationship. Multi-dimensional analysis provided additional information on the relationships between the variables and the sections studied. The greatest positive impact on the formation of the final HIR value had the variation of the riverbed slope and natural morphological elements of the bed bottom, while the greatest negative impact on HIR had the transformations observed in spot-check.

Automated riverbed composition analysis using deep learning on underwater images

Abstract. The sediment of alluvial riverbeds plays a significant role in river systems both in engineering and natural processes. However, the sediment composition can show high spatial and temporal heterogeneity, even on river-reach scale, making it difficult to representatively sample and assess. Conventional sampling methods are inadequate and time-consuming for effectively capturing the variability of bed surface texture in these situations. In this study, we overcome this issue by adopting an image-based deep-learning (DL) algorithm. The algorithm was trained to recognise the main sediment classes in videos that were taken along cross sections underwater in the Danube. A total of 27 riverbed samples were collected and analysed for validation. The introduced DL-based method is fast, i.e. the videos of 300–400 m long sections can be analysed within minutes with continuous spatial sampling distribution (i.e. the whole riverbed along the path is mapped with images in ca. 0.3–1 m2 overlapping windows). The quality of the trained algorithm was evaluated (i) mathematically by dividing the annotated images into test and validation sets and also via (ii) intercomparison with other direct (sieving of physical samples) and indirect sampling methods (wavelet-based image processing of the riverbed images), focusing on the percentages of the detected sediment fractions. For the final evaluation, the sieving analysis of the collected physical samples were considered the ground truth. After correcting for samples affected by bed armouring, comparison of the DL approach with 14 physical samples yielded a mean classification error of 4.5 %. In addition, based upon the visual evaluation of the footage, the spatial trend in the fraction changes was also well captured along the cross sections. Suggestions for performing proper field measurements are also given; furthermore, possibilities for combining the algorithm with other techniques are highlighted, briefly showcasing the multi-purpose nature of underwater videos for hydromorphological assessment.

River Habitat Survey: Does This Help to Explain the Nature of Water Mite (Acari and Hydrachnidia) Assemblages?

In the European Union, assessments of the quality of the aquatic environment based on aquatic invertebrates are mandatory. Biological methods are supplemented with hydromorphological assessments of watercourses. There are many studies analysing the relationships between aquatic invertebrates and the hydromorphological assessment of the environment by the River Habitat Survey (RHS) method, but thus far, there has been no detailed study including water mites (Acari, Hydrachnidia) and the application of this method. In the present study, the following research hypothesis was put forth: a hydromorphological characterization of habitats is a significant element explaining the nature of water mite communities, and the RHS method can be used to predict the characteristics of Hydrachnidia populations in a river. The research was carried out in a small lowland river, the River Krąpiel (north-western Poland). Six locations were selected as representative of some state of habitat modification for the assessment of the hydromorphological conditions of the river and the collection of biological samples. The following conclusions can be drawn from the research: (1) the biology and ecology of water mites make them suitable as bioindicators of the environment, including hydromorphological modifications, and (2) the hydromorphological characteristics of habitats explain the nature of water mite communities in the river at the level of general population parameters (number of specimens and species), while at the species level, general regularities in water mite fauna distribution in river ecosystems, the continuity of the river ecosystem, and characteristics at a smaller spatial scale (habitat scale) better explain water mite community structure than the hydromorphological indices determined for a given site or section of the river.

Outdoor River Activities: Relations with Geological Background and Extreme Events in the Perspective of Geoeducation

As for sport climbing, also for outdoor activities such as rafting and canyoning, a strong connection with geofeatures on a long and short time scale exists. For investigating this, three river segments were selected in the Sesia hydrographic basin (Sesia Val Grande UNESCO Global Geopark, Northwest Italy). Here, commercial rafting and canyoning activities are popular, and important geological features are present (Sesia Supervolcano, Insubric Line). The segments were investigated using partly IDRAIM (system for stream hydromorphological assessment, analysis, and monitoring). Bedrock features, confinement, sinuosity, bankfull bottom, morphological units, and steepness were characterized. The segments were hence divided in several reaches. Correlations on the long time scale were found mainly between the geology and bankfull bottom configuration, while sinuosity allowed us to highlight the possible structural control on the genesis of gorges. Moreover, the analysis of changes in a short time scale along the river segments after the extreme meteorological event occurred on 2–3 October 2020, highlighted a rapids difficulty variation, channels diversion, and woody–rocky debris accumulation in the bankfull, deeply influencing river activities. Through the proposed approach, new frontiers in the outreach of geosciences could be opened, especially in virtue of the several Sustainable Development Goals that could be achieved through river outdoor activities, among the others new employment opportunities for local operators.

The concept for innovative Comprehensive Assessment of Lowland Rivers.

Current river assessment methods focus on evaluating a single aspect (e.g. the physical and chemical quality of the water or its hydromorphological state) and usually do not integrate various factors. The lack of an interdisciplinary method makes it difficult to correctly assess the condition of a river as a complex ecosystem significantly influenced by humans. This study aimed to develop a novel Comprehensive Assessment of Lowland Rivers (CALR) method. It is designed to integrate and evaluate all-natural and anthropopressure-related elements that influence a river. The CALR method was developed using the Analytic Hierarchy Process (AHP). The application of the AHP allowed the assessment factors to be determined and given weights to define the importance of each assessment element. As a result of AHP analyses, the following ranks were determined for the six main parts of the CALR method: hydrodynamic assessment (0.212), hydromorphological assessment (0.194), macrophyte assessment (0.192), water quality assessment (0.171), hydrological assessment (0.152) hydrotechnical structures assessment (0.081). In the comprehensive assessment of lowland rivers, each of the six elements listed above is rated on a scale of 1-5 (where 5 means very good and 1 bad) and multiplied by an appropriate weighting. After summing up the obtained results, a final value is obtained, classifying the river. CALR can be successfully applied to all lowland rivers thanks to its relatively simple methodology. The widespread use of the CALR method may facilitate the assessment process and enable the comparison of the condition of lowland rivers worldwide. The research conducted in this article is one of the first attempts to develop a comprehensive method for evaluating rivers that considers all aspects.

Use of UAV Monitoring to Identify Factors Limiting the Sustainability of Stream Restoration Projects

The detection and mapping of riverscapes with Unmanned Aerial Vehicles (UAVs, drones) provide detailed, reliable, and operable spatial information in hydrological sciences, enhancing conventional field survey techniques. In this study, we present the results of long-term, optical RGB (red, green, blue) UAV monitoring of stream restoration projects to identify the positive and negative features that affect their sustainability. We determined quantitative and qualitative aspects of restoration, such as the restoration effect, the dynamics of fluvial processes, hydrological connectivity, and riparian vegetation. The study was based on six years of UAV monitoring in three restored streams in Prague, Czech Republic. The multitemporal riverscape models from the photogrammetric reconstruction served as a basis for the visual assessment, compliant with the standard hydromorphological assessment. Such a combined approach extends the potential of UAV monitoring by allowing for the use of existing classification schemes and data and the objective detection of critical features. The study pointed to the significant discrepancies in channel geometry between the planned restorations and realized restorations in all assessed projects as a general phenomenon. Multitemporal, optical RGB UAV monitoring then detected issues in qualitative aspects that limit restoration quality, such as water overuse, extensive eutrophication, or inefficient riparian shading.

An Analysis of Hydromorphological Index for Rivers (HIR) Model Components, Based on a Hydromorphological Assessment of Watercourses in the Central European Plain

Assessing the hydromorphological conditions of watercourses is a requirement of the Water Framework Directive (WFD) and national river status monitors (e.g., in Poland,the State Environmental Monitoring, and Water Monitoring coordinated by Chief Inspectorate of Environmental Protection). This paper evaluates the hydromorphological status of 10 watercourses (30 measurement sections) in Poland based on the multimetric Hydromorphological Index for Rivers (HIR). A new approach to the delineation of the river valley (small watercourses) is proposed. An analysis of the influence of river valley management on the value of HIR and its components was carried out using statistical methods (basic statistics, Mann–Whitney U Test and Ward’s cluster analysis). In addition, the relationship between the components of the HDS (Hydromorphological Diversity Score) and HMS (Hydromorphological Modification Score) was analyzed (Spearman’s Rank Correlation Coefficient). HIR values for the watercourse sections ranged from 0.553 to 0.825. HDS values ranged from 27.5 to 75.5 and HMS from 2.0 to 17.5. The results of the basic statistical analyses showed slight differences between the two river valley delineation methods. The Mann–Whitney U Test showed a significant difference in the test significance level of the HDS, HMS and HIR for the river valley delineation methods. Spearman’s rank correlation analysis showed that most of the HDS and HMS parameters components had a low degree of correlation. The juxtaposition of the two methods for delineating a river valley and its influence on the HIR allows for a better understanding of the interdependence between its parameters.

Riparian Plant Evapotranspiration and Consumptive Use for Selected Areas of the Little Colorado River Watershed on the Navajo Nation

Estimates of riparian vegetation water use are important for hydromorphological assessment, partitioning within human and natural environments, and informing environmental policy decisions. The objectives of this study were to calculate the actual evapotranspiration (ETa) (mm/day and mm/year) and derive riparian vegetation annual consumptive use (CU) in acre-feet (AF) for select riparian areas of the Little Colorado River watershed within the Navajo Nation, in northeastern Arizona, USA. This was accomplished by first estimating the riparian land cover area for trees and shrubs using a 2019 summer scene from National Agricultural Imagery Program (NAIP) (1 m resolution), and then fusing the riparian delineation with Landsat-8 OLI (30-m) to estimate ETa for 2014–2020. We used indirect remote sensing methods based on gridded weather data, Daymet (1 km) and PRISM (4 km), and Landsat measurements of vegetation activity using the two-band Enhanced Vegetation Index (EVI2). Estimates of potential ET were calculated using Blaney-Criddle. Riparian ETa was quantified using the Nagler ET(EVI2) approach. Using both vector and raster estimates of tree, shrub, and total riparian area, we produced the first CU measurements for this region. Our best estimate of annual CU is 36,983 AF with a range between 31,648–41,585 AF and refines earlier projections of 25,387–46,397 AF.

Hydromorphological Assessment as a Tool for River Basin Management: Problems with the German Field Survey Method at the Transition of Two Ecoregions

Since the Water Framework Directive (WFD) came into force in 2000, data on the hydromorphological quality have been collected for all rivers in Europe. In Germany, a reference-based classification scheme is used (LAWA 2000) for hydrological assessment. The question arises whether this method can compensate sufficiently for a change of ecoregion. In our study of the Hase River in NW Germany, the frequency of the river classes was compared between two ecoregions (Lower Saxonian Mountains vs. Northwest-German Lowlands). In the lowlands, the evaluation shows a significantly higher proportion of class 5 river sections. This can mainly be attributed to the main parameters, longitudinal section, riverbed structure and bank structure. While the bad results in the longitudinal section and bank structure can be explained by changes in geology and anthropogenic pressures, the evaluation scheme cannot sufficiently compensate for changes in the riverbed structure. This problem is aggravated by the inconsistent implementation of the evaluation scheme in Germany, where the federal states use different approaches with regard to section length. Using 100 m sections throughout the river course can lead to severely underestimating the number of structures. Further improvement and standardization in the evaluation scheme seem to be necessary for the adjustment of the field survey method to different ecoregions in Germany.

A Comparative Evaluation of Hydromorphological Assessment Methods Applied in Rivers of Greece

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.

Hydromorphological Assessment as the Basis for Ecosystem Restoration in the Nanxi River Basin (China)

Hydromorphology is a major component of riverine ecosystems. Therefore, proper assessments of the status quo, as well as the detection of pressures in river basins, are of high relevance. Process-based morphological methods have been developed, relying on a broad data basis and resulting in suitable instruments, such as the Morphological Quality Index (MQI). In this study, the hydromorphological status of the Nanxi river system in Eastern China was assessed by an adapted application of the MQI. Adaptations and amendments in the methodical approach were developed in cycles and carried out to transfer the well-approved method for European river systems to another geographical setting. The strengths of the tested approach are the few data requirements, the applicability for modified river basins, and the decoupling of historical information. The assessment of 161 river kilometers resulted in a hydromorphological status quo with the focus being a relative comparison of different sections ranging from “moderate” to “bad”, with an average classification of a “poor” state. On the one hand, the results build the basis for future restoration and river management planning, specifically, and on the other hand, they create a foundation for the development of an assessment method fitted for modified river systems conditions.

The assessment algorithm for sustainable development goals in the Hukiv, Dereluy, and Vyzhenka river basin systems of Chernivtsi oblast

The study deals with an integral assessment of hydromorphological and geoecological conditions of the Hukiv (flatland type of river), Dereluy (foothill type of river), and Vyzhenka (mountainous type of river) river basin systems (Figure 1). The indicators characterizing the river basin in the best way as a holistic system, the channel, floodplain, and watershed altogether, in natural reference conditions and in terms of human economic activity are addressed. The assessment hydromorphological test and geoecological monitoring of small rivers (SWOT-analysis) in accordance with the developed universal algorithm for hydromorphological assessment of small river basins for the sustainable development goals are generated and fulfilled. Interpretation maps for the sustainable development of the Hukiv, Dereluy and Vyzhenka rivers are created. The practical importance and relevance concerns the potential application of the proposed monitoring and the algorithm to solve methodological and applied problems related to the functioning of the systems “basin–river–human” and “basin–river–riverbed” in terms of modern human activity and needs; the need to modify consumer-type stereotypes for the use of natural resources, as well as to provide recommendations for enhancing the resource-efficient and sustainable activities in basin systems and small rivers.

Hydro-Morphological Assessment of Dittaino River, Eastern Sicily, Italy

The present conditions of the Dittaino River were investigated by using tools addressing different components of the IDRAIM (stream hydro-morphological evaluation, analysis, and monitoring system) procedure. After the segmentation of the river, the Morphological Quality Index (MQI) and the Morphological Dynamic Index (MDI) were assessed to analyze its morphological quality and to classify the degree of channel dynamics related to progressive changes occurring in the relative long-term (i.e., 50–100 years), respectively. The results show that 45% and 22% of the analyzed reaches (mainly located in highest zones of the hydrographic network) were, respectively, of high and good quality. The MQI class decreased to good and then to moderate in the downstream direction, and two reaches were of poor class. The highest MDI classes were also mainly identified in the highest zones of the hydrographic network. Some limitations (i.e., the elevated number of indicators, as well as their simplification) and strengths (i.e., the easy applicability to a large number of reaches) were identified during the application of the MQI method to the Dittaino River.

Hydromorphological assessment of Polish lakes: Elaborating the Lake Habitat Survey for Polish Lakes (LHS_PL) method and determining ecologically based boundary values for lake classification

AbstractThe Lake Habitat Survey for Polish Lakes (LHS_PL) is a method for the hydromorphological investigation of lakes employed for the assessment of the ecological status of surface water bodies in Poland. It was developed based on the British Lake Habitat Survey method. In 2015, after almost a decade of work on the adaptation, the LHS method was finally adjusted to Polish conditions, and since 2016, it has been implemented in the State Environmental Monitoring programme. This paper presents the assumptions and evolution of the method and the approach for determining boundary values for the high/good (H/G) and good/less than good (G/LTG) ecological status classes. The method involves the assessment of the morphological features of the lake and anthropogenic pressures at 10 observation plots as well as the analysis of hydrological alterations and anthropogenic activities within the lake basin and the entire catchment area. The data collected in the field are used to calculate the index of lake hydromorphological alteration, that is, the Lake Habitat Modification Score for Polish Lakes (LHMS_PL). The LHMS_PL values range from 0 to 144, where 0 means no modification and 144 refers to a hydromorphologically highly modified state. The boundary values for the H/G and G/LTG status classes have been determined using the quartile method based on the relationship between hydromorphological modifications of lakes and the condition of the phytoplankton and macrophyte communities therein.

Hydromorphological and socio-cultural assessment of urban rivers to promote nature-based solutions in Jarabacoa, Dominican Republic

In Latin America and the Caribbean, river restoration projects are increasing, but many lack strategic planning and monitoring. We tested the applicability of a rapid visual social–ecological stream assessment method for restoration planning, complemented by a citizen survey on perceptions and uses of blue and green infrastructure. We applied the method at three urban streams in Jarabacoa (Dominican Republic) to identify and prioritize preferred areas for nature-based solutions. The method provides spatially explicit information for strategic river restoration planning, and its efficiency makes it suitable for use in data-poor contexts. It identifies well-preserved, moderately altered, and critically impaired areas regarding their hydromorphological and socio-cultural conditions, as well as demands on green and blue infrastructure. The transferability of the method can be improved by defining reference states for assessing the hydromorphology of tropical rivers, refining socio-cultural parameters to better address river services and widespread urban challenges, and balancing trade-offs between ecological and social restoration goals.

Hydromorphological assessment in North Morocco: The case of Martil River

The present study is about an assessment of the Martil River restoration, which crosses Tetouan and Martil city in Northern Morocco. The evaluation compromises rainfall occurrence of 30 years, riparian habitats, and the river flow of 12 years. The rainfall analysis was carried out by the Standard Precipitation Index (SPI). Only three stations that contain continuous monthly precipitation data were considered. The river health and water quality were determined by the QBR (Riparian Habitat Quality), while the environmental flow was estimated by Tennant method. SPI results show a rainfall increment pattern with regular, extreme, and plentiful downpours causing rough deluges and floods. The ultimate flow result to support the river habitats was found 60% of the natural flow in the main channel. This study highlights the stream’s unhealthy water, which falls within the low-quality water category downstream the river under anthropogenic pressure, while good to excellent quality was scored upstream the watershed. Tennant outcomes were discovered 2.40 m³/s as 30% and 5.51 m³/s as 60%, while 10% of the flow was found to be not adequate for habitats in the Martil River.

Hydromorphological Index for Rivers: A New Method for Hydromorphological Assessment and Classification for Flowing Waters in Poland

Hydromorphological Index for Rivers: A New Method for Hydromorphological Assessment and Classification for Flowing Waters in Poland

Disentangling the Main Components of Hydromorphological Modifications at Reach Scale in Rivers of Greece

The Water Framework Directive (WFD) requires from member states to monitor hydromorphological features of rivers in order to assess their ecological quality. Thus, numerous hydromorphological assessment methods have been developed with most of them focusing on the dynamics of hydrology, geomorphology and riparian zone extent. Within the scope of this study, we assessed the hydromorphological features of 106 river reaches distributed among thirteen WFD River Basin Districts (RBDs) to identify the main drivers of hydromorphological perturbation at a national scale. The studied reaches reflect a wide range of natural variability as they include various types of watercourses extending from lowlands to mid-altitude and mountainous systems. We employed the River Habitat Survey (RHS), and we recorded hydromorphological features and modifications in both banks and the channel bed along 500 m for each reach. Then, the Habitat Modification Score (HMS) and the individual sub-scores that indicate the extent of specific modifications (e.g., bridges, fords, weirs, bank reprofiling, bank reinforcement, etc.) were calculated in order to a) assess the severity of the total artificial modification and b) to highlight the most common and severe causes of overall alteration. The results showed that alterations such as reprofiling and reinforcement of banks contributed the most to the total HMS followed by the presence of fords and bridges. Particularly, the bank alterations indicate a serious deterioration of the longitudinal profile of the reaches, while the occurrence of many fords and bridges is the main cause for perturbations that affect locally the stream cross-sectional profile. Overall, these results compile a first nationwide assessment of the hydromorphological status of Greek rivers in line with the WFD and set the basis for further research that will focus on the diversity of stream habitat features as a measure for the overall ecological quality.

An assessment of the hydromorphological conditions of the middle and lower Guadalquivir River (southern Spain)

ABSTRACTAn overall hydromorphological assessment of the middle to lower Guadalquivir River (southern Spain) was conducted using the Morphological Quality Index (MQI) and a novel extension, the Hydro-Morphological Quality Index (HMQI), with the following aims: (1) investigate the morphological problems and (2) describe and test the HMQI on a case study characterized by relevant hydrological alterations related to the presence of dams. The assessment was preceded by a delineation phase of spatial units using the REFORM hydromorphological framework. The MQI results show that “moderate” is the dominant quality class, with some cases falling into the poor class and a few cases with good conditions. The results in terms of the HMQI are slightly worse, given the remarkable hydrological alterations related to the dams, with approximately half of the reaches classified as poor and the remaining half classified as moderate. The main conclusions of this case study are that (1) the methodology is effective in diagnosing hydromorphological problems and in allowing a sound understanding of the responses to pressures (i.e., cause-effect relationships), and (2) the overall evaluation based on HMQI appears to be a useful integration with the MQI, particularly in a case study characterized by a large number of dams.

AN INTEGRATED APPROACH TO RIVER VALLEY REVITALISATION

Rivers have always been a unique space in urban landscapes. Regrettably, the river-town relationship was disturbed in the 19th and at the beginning of the 20th century as industrial plants and districts were established at banks, which changed the urban structure. This resulted in degradation of riverscapes among other things. Today, attempts are made to revitalise the areas and use them for ecological, recreational, and other purposes. The paper presents an integrated approach to river valley revitalisation – demonstrated on the Skawinka river, flowing through Skawina, an industrial town in Poland. An integrated approach could indicate local development possibilities of river valley and thereby strengthen the competitiveness of the area. The study employed the Landscape and Hydromorphological Assessment of River Valleys Method, focusing on hydromorphological, landscape, and integrated factors. Proposing an integrated approach to the Skawinka river valley revitalisation presents a procedure that indicates possibilities for local development and thereby strengthening the competitiveness of this region. The guidelines for the revitalisation project for this river indicate that if the river was made generally accessible, it may become an important location for social and economic life. At the same time it might have a recreational and educational function.