Rivers In Chile Research Articles

Towards durable legal protections for rivers in Chile

ABSTRACT The protection of Chile’s rivers is a matter of ongoing public and constitutional interest in the wake of Chile’s failed 2019–2024 constitutional reforms. In this article we review and evaluate opportunities for greater legal protection and restoration of rivers in Chile. The legal analysis was complemented by a survey of social attitudes about river protection needs and several interviews with key experts and stakeholders, which found strong concern for enhanced river protection mechanisms in Chile. We conclude by outlining critical pathways towards durable legal protections for the future of Chile’s rivers.

Investigating river–aquifer interactions using heat as a tracer in the Silala river transboundary basin

AbstractThis article reviews scientific studies in which heat was used as a natural tracer to investigate stream–aquifer interactions in the Silala River in Chile and provide evidence that was used to support a legal dispute between Chile and Bolivia over the status and use of the waters of this watercourse. Streambed temperature time series at various locations downstream of the Chile‐Bolivia international border showed that water flows downwards through the streambed sediments, from the river towards the fluvial aquifer. These findings are consistent with hydraulic head measurements performed at the study site. Additionally, fiber‐optic distributed temperature sensing (FO‐DTS) methods were employed to observe river temperatures with a spatial resolution of the order of 0.5 m in a river reach of ~1.3 km. FO‐DTS technology allowed detection of various warm springs that discharged their waters into the Silala River, as well as the location of an artesian well that supplies the river with ~90 L/s of deep groundwater at ~20 °C. The results provided improved understanding of the Silala River hydrogeology, and were used to calibrate and validate a groundwater model of the system, reported elsewhere. Both methodologies demonstrated that the river is indeed a system of surface waters and groundwaters interacting as a unitary whole, a key aspect of the definition of an international watercourse, and generated valuable scientific evidence to support a major international legal dispute.This article is categorized under: Science of Water > Hydrological Processes Science of Water > Methods

An Urgent Dialogue between Urban Design and Regulatory Framework for Urban Rivers: The Case of the Andalién River in Chile

Climate change scenarios predict alarming levels of water scarcity and damaging flood events worldwide. Considering hydric systems in integrated spatial planning will be crucial in mitigating, adapting, and reversing climate change’s catastrophic effects. This paper focuses on fluvial restoration as part of urban and territorial regulatory frameworks in the Andalién River and the city of Concepción in Chile. We consider three work scales: (i) basin, (ii) river reaches which focus on the city–river interplay, and (iii) site-specific, deepening the discussion around the last two. The objective is to elaborate an interdisciplinary dialogue between urban design, fluvial dynamics, and the Chilean regulatory framework where property rights play a predominant role in the management of natural resources (water and land). In this regard, the ‘New Latin American Constitutionalism’ offers concrete possibilities to operationalize an emerging paradigm that recognizes legal personhood for Nature. The incorporation of an ecological function to property rights emerges as a new way in which the principles of resilient urban development can be applied in order to combine river dynamics and urban growth.

Assessment of pumped hydropower energy storage potential along rivers and shorelines

The increasing share of renewable energy sources, e.g. solar and wind, in global electricity generation defines the need for effective and flexible energy storage solutions. Pumped hydropower energy storage (PHES) plants with their technically-mature plant design and wide economic potential can meet these demands. Especially, in the vicinity of volatile renewable energy plants they can directly balance frequency fluctuations with short reaction times and large capacities. Therefore, site identification for new pumped hydropower energy storage schemes is a crucial issue intensifying the research needs of developing new algorithms for automated search routines. As current methods neglect shape constraints for ring dams, a new method that incorporates the evaluation of the shape is proposed. In addition, the area slope threshold is transformed into site quality measures removing a hard cut-off at a certain limit. The developed method is able to locate and evaluate suitable ring dam locations along rivers but can also be applied to shore lines or existing lower reservoirs. The effectiveness of the routine is demonstrated and successfully verified by locating promising locations along two rivers in Chile.

Automatic river planform identification by a logical-heuristic algorithm

A solution is provided to automatically identify river reaches based on their planform typologies via a holistic synthesis of multi-dimensional, quali-quantitative information. Inspired by fuzzy logics, an algorithm is proposed which appraises the degree of fit of a range of archetypes based on formal criteria, applied over a discretized version of the river. The algorithm is fed by the values of a set of indicators relevant to the formal criteria. Indicators are determined from interpretation of remotely sensed data for each discrete “slice”. To ensure a spatially holistic view, the local indicators are first integrated over a variable significant length, thereby guaranteeing contextualization at the appropriate scale. For each indicator a specific Value Function (VF) translates its objective value into a partial fitness judgment; these judgments are then integrated within a multiattribute VF. The locally highest scoring VF determines the corresponding planform choice in each slice. As a by-product, the stretch (collection of consecutive slices) corresponding to that planform archetype is identified. Implementation of the algorithm for the Baker River in Chile shows promising results. The approach ensures self-consistency and repeatability of outputs. Beyond an initial subjective assessment of input criteria based on expert judgment, the method can be fully automated. As such it can support systematic, large scale river analyses and monitoring applications.

CrAssphage for fecal source tracking in Chile: Covariation with norovirus, HF183, and bacterial indicators

Anthropogenic fecal pollution in urban waterbodies can promote the spread of waterborne disease. The objective of this study was to test crAssphage, a novel viral human fecal marker not previously applied for fecal source tracking in Latin America, as a fecal pollution marker in an urban river in Chile. Human fecal markers crAssphage CPQ_064 and Bacteroides HF183, the human pathogen norovirus GII, and culturable fecal indicator bacteria (FIB) were quantified at six locations spanning reaches of the Mapocho River from upstream to downstream of Santiago, as well as in repeated sub-daily frequency samples at two urban locations. Norovirus showed positive correlation trends with crAssphage (τ = 0.57, p = 0.06) and HF183 (τ = 0.64, p = 0.03) in river water, but not with E. coli or enterococci. CrAssphage and HF183 concentrations were strongly linearly related (slope = 0.97, p < 0.001). Chlorinated wastewater effluent was an important source of norovirus GII genes to the Mapocho. Precipitation showed non-significant positive relationships with human and general fecal indicators. Concentrations of crAssphage and HF183 in untreated sewage were 8.35 and 8.07 log10 copy/100 ml, respectively. Preliminary specificity testing did not detect crAssphage or HF183 in bird or dog feces, which are predominant non-human fecal sources in the urban Mapocho watershed. This study is the first to test crAssphage for microbial source tracking in Latin America, provides insight into fecal pollution dynamics in a highly engineered natural system, and indicates river reaches where exposure to human fecal pollution may pose a public health risk.

WATERSCAPES IN WALLMAPU: LESSONS FROM MAPUCHE PERSPECTIVES

abstract This article reflects on the multiple worlds generated around waterscapes in the diverse Mapuche territory, Wallmapu. We contrast the responses of three Mapuche communities to external interventions and water availability in the Chimehuin and Lepá rivers in Argentina, and the Huenehue River in Chile. The comparison reveals the nature of Mapuche waterscapes, the tensions provoked by the global economy, and its impacts on water management. Mapuche communities establish an intersubjective relationship with water, securing and protecting their water supply. Waterscapes are constituted as living entities where human and nonhuman stories converge and on which biocultural memory is periodically enriched in its response to a changing environment. We conclude that coexistence between Mapuche and non-Mapuche worlds, however diverse the communities might be, is sustained through equivocal relations and partial connections. Established views of water management in Wallmapu could be greatly enriched by the Mapuche’s views and practices.

ADSORPTION-DESORPTION OF TRACE ELEMENTS IN SEDIMENTS OF THE MAIPO RIVER BASIN

We studied the adsorption-desorption of Cu, Mn, Pb and Zn in Maipo river basin, one of the most perturbed rivers in Chile, and thus determined its tolerance to the addition of these metals into the sediments and the possibility of transferring the metals from the sediments to the water column. Sediments were sampled from six sites from the river basin and characterized by their pH, electrical conductivity, organic carbon, total organic carbon, water soluble phosphorus and texture. Batch sorption and kinetics experiments were conducted to obtain the retained amounts onto the sediment samples. The initial concentration of trace elements in the sediment was quantified by AAS. The metals were present in most of the sites. Sorption parameters such as Kd and Koc were determined. Metals were adsorbed in the sediment, with Mn showing the lowest affinity, Kd and Koc values support these results. Desorption less than 1% were observed for Cu, while Pb and Zn ranged from 0.6% to 6.8% and those for Mn ranged from 0% to 17.6% across sites. The tolerance of the Maipo River to metal adsorption in sediments was as follows: Pb˃ Cu˃ Zn ˃Mn. Desorption analysis showed that both Zn and Mn could be transferred from the sediment to the water column. The strongest correlation occurs between the pH and Kd-Pb, indicating that at higher pH values, the Pb adsorption was unfavorable, while the correlation was moderate for Cu, Mn and Zn. On the other hand, there are positive correlations between pairs of metals such as Mn-Cu, Zn-Cu, and Zn-Mn, indicating the competition of these metals for the adsorbent sites. The high concentration of Mn found in the sediment and the possibility of being transferred to the water column, due to its easy of desorption, suggest concern due to its potential risk to aquatic biota.

Geochemistry of Chilean Rivers Within the Central Zone: Distinguishing the Impact of Mining, Lithology and Physical Weathering

Several rivers of Chile from the latitude 30°–38° have been sampled during a stable anticyclonic period (October 2008). Firstly, our aim was to evaluate the dissolved chemical composition (major and trace elements) of poorly known central Chilean rivers. Secondly, we used a co-inertia analysis (see Doledec and Chessel in Freshw Biol 31:277–294, 1994) to explore the possible relationships between the concentrations of elements and the environmental parameters [surface of the basin (km2)/mining activity (%)/average height (m)/watershed mean slope (%)/% of the surface covered by vegetation, sedimentary rocks, volcano-sedimentary rocks, volcanic rocks, granitoid rocks/erosion rate (mm/year)]. Globally, the major elements concentration could be explained by a strong control of mixed silicate and carbonate and evaporate lithology. The statistical treatment reveals that the highest metal and metalloids loads of Tinguiririca, Cachapoal, Aconcagua, Choapa, Illapel and Limari could be explained by the contribution of the mining activities in the uppermost part of these watersheds and/or by the higher geochemical background. Indeed, it remains difficult to decipher between a real mining impact and a higher geochemical background. Even if these rivers could be impacted by AMD process, the size of these watersheds is capable of diluting AMD waters by the alkaline character of tributaries that induce acid neutralization and decrease the level of metals and metalloids.

Modelling Hydrological Components of the Rio Maipo of Chile, and Their Prospective Evolution under Climate Change

We used the Poly-Hydro model to assess the main hydrological components of the snow-ice melt driven Maipo River in Chile, and glaciers’ retreat under climate change therein until 2100. We used field data of ice ablation, ice thickness, weather and hydrological data, and precipitation from TRMM. Snow cover and temperature were taken from MODIS. We forced the model using weather projections until 2100 from three GCMs from the IPCC AR5, under three different radiative concentration pathways (RCPs 2.6, 4.5, 8.5). We investigated trends of precipitation, temperature, and hydrology until 2100 in the projection period (PR, 2014–2100) and the whole period (CM 1980–2100, composite), against historical trends in control period (CP, 1980–2013). We found potentially increasing temperature until 2100, except for Spring (OND). In the PR period, yearly flow decreases significantly under RCP85, on average −0.25 m3·s−1·year−1, and down to −0.48 m3·s−1·year−1, i.e., −0.4% year−1 against CP yearly average (120 m3 s−1). In the long run (CM) significant flow decrease would, occur under almost all scenarios, confirming persistence of a historical decrease, down to −0.39 m3·s−1·year−1 during CM. Large flow decreases are expected under all scenarios in Summer (JFM) during PR, down to −1.6 m3·s−1·year−1, or −1% year−1 against CP for RCP8.5, due to increase of evapotranspiration in response to higher temperatures. Fall (AMJ) flows would be mostly unchanged, while Winter (JAS) flows would be projected to increase significantly, up to 0.7 m3·s−1·year−1 during 2014–2100, i.e., +0.9% year−1 vs. CP under RCP8.5, due to large melting therein. Spring (OND) flows would decrease largely under RCP8.5, down to −0.67 m3 s−1·year−1, or −0.4% year−1 vs. CP, again due to evapotranspiration. Glacier down wasting is projected to speed up, and increasingly so with RCPs. Until 2100 ice loss would range from −13% to −49% (−9%, and −39% at 2050) of the estimated volume at 2012, which changed by −24% to −56% (−21%, and −39% at 2050) vs. ice volume in 1982, thus with rapider depletion in the first half of the century. Policy makers will have to cope with modified hydrological cycle in the Maipo River, and greatly decreasing ice cover in the area.

The first 300‐year streamflow reconstruction of a high‐elevation river in Chile using tree rings

ABSTRACTIn central Chile, increasing demand for water and decreasing runoff volumes due to drier conditions have placed catchments in this zone under water stress. However, scarcity of observed data records increases the difficulty of planning future water supply. Instrumental records suggest a reduction in streamflow over the last 56 years. However, this change is not statistically significant and the lack of meteorological stations with long records in this mountainous region hampers a deeper analysis, motivating the use of tree rings to analyse whether these changes are part of a long‐term trend. This work represents the first high‐elevation runoff reconstruction in Chile using 300 years of tree ring chronologies of Araucaria araucana and Astroceudrus chilensis. The upper part of Biobío river melting season runoff (October–March) and pluvial season runoff (April–September) was reconstructed and analysed to investigate the influence of large‐scale climatic drivers on runoff generation, current drought trends and to improve the understanding of climate variability in this region. We obtained positive correlations between the 20‐year moving average of reconstructed pluvial season runoff and reconstructed Pacific Decadal Oscillation (PDO), which is indicative of multi‐decadal variability. We also found a negative correlation between the 11‐year moving average of reconstructed melting season runoff and the PDO and positive correlations with the Southern Annular Mode (SAM). Important differences in the runoff variability of the upper and the lower part of the catchment were identified which are in part led by the influence of the large‐scale climatic features that drive runoff generation in both regions. We found that the changes observed in the instrumental records are part of multi‐decadal cycles led by the PDO and SAM for pluvial season runoff and melting season runoff, respectively.

Drones and digital photogrammetry: from classifications to continuums for monitoring river habitat and hydromorphology

Recently, we have gained the opportunity to obtain very high‐resolution imagery and topographic data of rivers using drones and novel digital photogrammetric processing techniques. The high‐resolution outputs from this method are unprecedented, and provide the opportunity to move beyond river habitat classification systems, and work directly with spatially explicit continuums of data. Traditionally, classification systems have formed the backbone of physical river habitat monitoring for their ease of use, rapidity, cost efficiency, and direct comparability. Yet such classifications fail to characterize the detailed heterogeneity of habitat, especially those features which are small or marginal. Drones and digital photogrammetry now provide an alternative approach for monitoring river habitat and hydromorphology, which we review here using two case studies. First, we demonstrate the classification of river habitat using drone imagery acquired in 2012 of a 120 m section of the San Pedro River in Chile, which was at the technological limits of what could be achieved at that time. Second, we review how continuums of data can be acquired, using drone imagery acquired in 2016 from the River Teme in Herefordshire, England. We investigate the precision and accuracy of these data continuums, highlight key current challenges, and review current best practices of data collection, processing, and management. We encourage further quantitative testing and field applications. If current difficulties can be overcome, these continuums of geomorphic and hydraulic information hold great potential for providing new opportunities for understanding river systems to the benefit of both river science and management. WIREs Water 2017, 4:e1222. doi: 10.1002/wat2.1222This article is categorized under: Water and Life &gt; Nature of Freshwater Ecosystems Water and Life &gt; Methods

Paternity Outcomes in the Freshwater Gastropod, Chilina dombeiana in the Biobío River, Chile.

Studying the mating system of obligate aquatic organisms that inhabit river ecosystems is important for understanding its evolution as well as the role of biological and environmental factors in modulating population dynamics and species distributional patterns. Here, we studied the reproductive strategy of the Chilean endemic freshwater snail, Chilina dombeiana, in the Biobío River, one of the largest rivers in Chile. This species has a low potential for dispersal given the absence of a free-swimming larval stage (benthic larval development) and given that adults have a low capacity for mobility. We hypothesized that: 1. Females would mate with different males (polyandry) resulting in intrabrood multiple paternity, 2. Individuals from closer sites would be more related than individuals from distant sites, and 3. Male parental contributions would be unevenly distributed within broods. Individuals from three different sites were sampled along the river: upper, mid, and river mouth. In the laboratory, hatching juveniles from a total of 15 broods were collected for paternity analyses. We used microsatellite markers and the programs GERUD and COLONY to determine whether multiple paternity exists and to estimate the contribution of different males to the brood. We found that multiple paternity was very common at all of the sites analyzed with as many as 8 males fertilizing a single female and a mean of 4.2 fathers per brood estimated by COLONY. Sire contribution was skewed to particular males in several broods. In addition, overall relatedness among broods for the three sites ranged from 0.17 to 0.45 with evidence of many half-siblings. Relatedness differed among the three sites. Particularly in upstream sites or in anthropogenically disturbed populations, the high levels of multiple paternity observed in C. dombeiana may be an efficient strategy to avoid inbreeding and prevent the loss of genetic diversity within populations.

River Restoration and Rehabilitation as a New Urban Design Strategy: Learning to Re-see Urban Rivers

This study analyses how river restoration-rehabilitation concepts can be transferred from natural settings to constructed environments and thus form part of an urban design strategy. In contrast to conventional civil engineering, this strategy explores how hydraulic challenges can be tackled through instead of against nature. The study focuses on urban rivers in Chile where unstable geographical and environmental conditions in combination with limited budgets require innovative solutions. The methodology uses research by design. From an environmental viewpoint, river restoration know-how is shifted from a restoring tool to a spatial analysis tool focused on understanding natural spatial processes. The outcome of this study is a cartography that maps the dynamic interplay between the natural water system and the city of Concepcion’s environmental conditions on the one hand and the relationship between the river landscape and urban development on the other.

Sampling of riverine litter with citizen scientists--findings and recommendations.

The quantity and composition of litter at riversides and in the surface waters, as well as the occurrence of illegal dumping sites, were studied along four rivers in Chile. Data generated by volunteers were compared to the results from a professional survey, using an identical protocol. Litter was found in considerable quantities at the riversides and in the surface waters at all the sites investigated. A generalized linear mixed model analysis showed that the recorded litter densities did not differ between volunteers and professionals, even after controlling for river, site, or distance between sampling locations, demonstrating that the volunteers successfully applied the sampling protocol. Differences occurred with respect to litter composition, which is most likely due to difficulties in the classification of litter items and particles and to the underestimation of litter present in surface water samples. Even though this study was only conducted at a small number of rivers and sites, a comparatively consistent pattern of direct and intentional litter deposition at riversides was recorded, highlighting that river basins require more protection. The results also show that the citizen science approach can be a suitable means for more extensive litter surveys at riversides and in other natural environments.

Enfermedad y daño. Etiología y tratamiento de la viruela entre las sociedades nativas de Araucanía (fines del siglo XVIII)

In the year of 1791, a smallpox epidemic which affected the Indian populations of the Arauco frontier –south of Bio-Bio river in Chile– worried the colonial authorities of Concepcion, due to the fear that the Spanish inhabitants of that region could also get infected. Acting according to the contagion paradigm, they imposed a cordon sanitaire in order to isolate them from the Natives, and suggested these do the same. Also, conscious that the plague was commonly attributed to Spanish witchcraft, they hurried to offer medicine and medical advice, in order to show there was no will to cause damage. The responses of the different Indian groups demonstrated the co-existence of a wide variety of perspectives regarding the etiology of smallpox and the possible paths of action: from a personalist conception which attributed it to witches’ activities, to the admission of their own inability to find proper treatment, which led to the acceptance of Spanish medicines. The general picture shows a native model of the illness that is both conservative and innovative, complex and dynamic at the same time. The description of those events, found in a folder which was later sent to Spain, and the references contained in other colonial documents, allow the examination of the epidemiologic event using as a comparative context the conceptualizations now current among the Mapuche. They also allow the analysis of dominant conceptions concerning illness among the Spaniards in the late eighteenth century.

Construction of a typology system for rivers in Chile based on the European Water Framework Directive (WFD)

To assess the current status of surface waters, it is necessary, as a first step, to have a system that includes a set of criteria for classifying and describing each existing surface water body. In this article, a new river typology system for Chile based on the Water Framework Directive of the European Union is shown. This system was created following a top down and a priori approach and was based on an accurate review of scientific literature, interviews and workshops with experts in Chilean aquatic ecosystems. The system consisted of five ecoregions (large areas with homogenous hydrological and climatic conditions) and a set of abiotic criteria with their classes. It was assumed that each abiotic criterion was a control factor for freshwater ecosystems. It is expected that this system will organise knowledge about the biocenosis distribution of the Chilean freshwater ecosystem and also provide an operative tool for water quality monitoring based on biological indicators.

Video monitoring and field measurements of a rapidly evolving coastal system: the river mouth and sand spit of the Mataquito River in Chile

Cienfuegos R., Villagran M. ,Aguilera J.C., Catalán P., Castelle B., Almar R,, 2014. Video monitoring and field measurements of a rapidly evolving coastal system: the river mouth and sand spit of the Mataquito River in Chile. In: Green, A.N. and Cooper, J.A.G. (eds.), Proceedings 13th International Coastal Symposium (Durban, South Africa), Journal of Coastal Research, Special Issue No. 70, pp. 639–644, ISSN 0749-0208.The understanding of morphological processes controlling the evolution of sand spit reformation after a tsunami impact is a challenging and interesting topic, especially in highly energetic and micro tidal environments. A field campaign performed during December 2012 at the Mataquito River mouth in Chile, allowed us to simultaneously monitor topo-bathymetry evolution, wave climate, tidal range, swash zone dynamics and upper beach face evolution over a portion of its sand spit. A video system was set up for a continuous and long-term monitoring of the evolution of the river mouth and sand spit. Primarily, in this work we focus on the application of a video-derived shoreline detection method to assess shoreline evolution and beach cusps migration at hourly scales. We test the method performance on short-term episodic migration of beach cusps recorded during the campaign. Beach face variations at a daily scale were observed, which can be attributed to the migration of beach cusps in the alongshore direction, and linked to wave forcing and alongshore sediment transport.

Characterization and comparison of microphytoplankton biomass in the lower reaches of the Biobío River and the adjacent coastal area off Central Chile during autumn winter conditions

The Biobio River in central Chile is the third largest watershed and second largest river in Chile in terms of discharge volume. Three sampling campaigns were made in the lower reaches of the river and the adjacent coastal ocean to evaluate the influence of the river plume on the physical/chemical conditions and the abundance/biomass of microphytoplankton during autumn-winter conditions. In addition, a preliminary quantification of riverine nutrients, dissolved silica, and phytoplankton carbon flux to the adjacent ocean was also conducted. High nitrate (NO3 - ) and silicic acid (Si(OH)4) concentration (>18 and 50 µM, respectively) was observed in the lower reaches of the river during all field campaigns. Si(OH)4 was even high in surface river plume waters. Hydrographic conditions indicate that river plume waters were piled coastward, and they could drove to the south at the Arauco Gulf. In all sampling, highest microphytoplankton biomass (>5000 μgC m -3 ) was associated to the lower reaches of the river and river plume waters as they were moving southward. During autumn-winter conditions a significant flux of phytoplankton carbon and nutrients to the adjacent coastal ocean also played an important role in the high biological productivity of this coastal upwelling area. These preliminary results evidence the need to conduct large-term studies, which should consider the importance of these allochthonous carbon sources in global carbon budgets and coastal food-web models.

Response of the fish community to human‐induced changes in the Biobío River in Chile

Summary1. The Biobío River basin of south‐central Chile exhibits the greatest species richness of all rivers in Chile, where it is one of the most important rivers for human use. Use for provision of drinking water, irrigation, sewage effluents, hydropower generation and industry has increased dramatically during the last decade. To help understand the effects of human activities on the Biobío River, we document recent changes in the fish community.2. In this study, current patterns of distribution and abundance of fishes were compared with the expected longitudinal pattern, and to historical data from studies conducted before the rapid development of the last decade. Fish distribution, biomass, abundance and diversity were studied at eight sampling stations in the middle and lower zones of the river in both high and low flow seasons.3. Contrary to the pattern observed in less impacted river systems, species richness (S), diversity (H′) and abundance [calculated catch per unit effort (CPUE)] all tended to decrease downstream from the uppermost sampling locations. Mean S decreased from 7.9 to 5.4, mean H′ decreased from 0.7 to 0.4, and mean CPUE decreased from 111 to 43 from hyporithral to potamal locations.4. Comparison with previous records indicates loss or reduction in distribution of native species, and a concurrent expansion in distribution and abundance of tolerant introduced species (e.g. Gambusia holbrooki, and Cyprinus carpio) over the last 10–15 years. These comparisons suggest a large‐scale and long‐term effect of recent human impacts on the river.