Hydrodynamics are a major environmental factor on intertidal rocky shores. Morphological response... more Hydrodynamics are a major environmental factor on intertidal rocky shores. Morphological responses to this factor are expected to strongly influence spatial distribution of species across environmental gradients. We here analysed the shell phenotypic variability of the limpet Fissurella latimarginata using geometric morphometric analysis. The limpets were obtained from a sheltered intertidal coastal area and a wave-exposed environment. To determine whether the shell shape variation of the intertidal molluscs is linked to their resistance to differential intertidal wave exposure, mesocosm studies were developed in a hydraulic flume to explore the effects of hydrodynamic forces on this limpet species. A unidirectional current was used to test the impacts of step-by-step increased current flow velocities for each limpet. The phenotypic variability observed in the populations of F. latimarginata was associated with habitats characterized by contrasting wave exposure. Limpets from expose...
Countries growing rates are directly related to energy production. Therefore, developed and devel... more Countries growing rates are directly related to energy production. Therefore, developed and developing nations are focused on hydropower and dam construction; on the contrary dam removal practices are significantly different among nations, demonstrating the former group a lesser interest on removing structures. Chiles hydropower generation corresponds to 50% of the current grid, having a potential capacity to double the current situation. Thus: ¿What tools can we apply to assess the potential impacts on our rivers?
Supplementary_Materials_V1 for Evaluation of extremal hypotheses in an undeveloped alluvial river... more Supplementary_Materials_V1 for Evaluation of extremal hypotheses in an undeveloped alluvial river by Andrew W Tranmer, Diego Caamaño and Peter Goodwin in Progress in Physical Geography: Earth and Environment
The installation of hydroelectric plants has generated multiple environmental impacts on the worl... more The installation of hydroelectric plants has generated multiple environmental impacts on the world’s river systems. In central Chile, the impacts of hydroelectric reservoir operation have been documented in ecological and hydrologic regime terms. This investigation assesses the changes in channel morphology, vegetation distribution, and flows in the middle section of the Maule River during the period following the start-up of a hydroelectric plant. Changes in fluvial morphology (active area) and land cover are quantified using LANDSAT images, contrasted with a vegetation sampling and flow analysis. The results show a 12% decrease in active areas of the river, indicating a loss of geomorphological diversity. Within the active channel, there was a gradual increase in plant-covered surface area, which reached 159% between 1989 and 2018, mainly due to reductions in water (−61%), active bar (−35%), and bare soil surface areas (−29%). The changes were evident ten years after plant operati...
Modeling the effects of pulsed versus chronic sand inputs on salmonid spawning habitat in a low-g... more Modeling the effects of pulsed versus chronic sand inputs on salmonid spawning habitat in a low-gradient gravel-bed river
Abstract The indeterminate channel problem arises from uncertainty in finding a closure relation ... more Abstract The indeterminate channel problem arises from uncertainty in finding a closure relation for alluvial channels created by self-organizing erosional and depositional processes. Extremal hypotheses have been proposed as one potential approach to closing the system of governing equations for alluvial channels. Many different extremal hypotheses have been presented, but no substantive evidence has been developed to select which hypothesis may be most appropriate for natural alluvial river systems. This paper evaluates the ability of ten extremal hypotheses to identify dynamic equilibrium across a geomorphic gradient in the remote and undeveloped mid-latitude watershed of Rio Murta, Chile. This study (a) introduces extremal hypotheses, (b) describes the field site and geomorphic conditions, and (c) examines which extremal hypotheses are supported by the field data in identifying the evolutionary trend toward dynamic-equilibrium. The extremal hypotheses that identified dynamic equilibrium within the geomorphic gradient in the field are: (1) minimum kinetic energy, (2) minimum specific stream power, (3) maximum friction factor, and (4) maximum total friction factor, which collectively support minimizing kinetic energy of the system.
Progress in Physical Geography: Earth and Environment
Recent work in the undeveloped Rio Murta Basin, located in Chilean Patagonia, identified an evolu... more Recent work in the undeveloped Rio Murta Basin, located in Chilean Patagonia, identified an evolutionary trend in the fluvial system as it progresses toward and away from dynamic equilibrium. A location-for-time-substitution model employed over the longitudinal extent of a 16 km study site assessed the performance of extremal hypotheses in identifying dynamic equilibrium conditions. Numerous extremal hypotheses were successful in identifying the spatial trend, but no means were available to discern differences between them. Thus, this study uses field measurements within the evolutionary trend to propose a new metric for evaluating extremal hypotheses. A thorough review and synthesis of the extremal approach are additionally presented. The new method compares theoretical predictions against field-measured values to determine which extremal hypothesis is most effective in identifying the condition of dynamic equilibrium in a gravel-bed river. Channel width and depth are identified as...
The volume, temporal and caliber of sediment supplied to gravel-bed rivers can have considerable ... more The volume, temporal and caliber of sediment supplied to gravel-bed rivers can have considerable effects on stream characteristics. In particular, fine sediment has critical effects on stream biota. Here, we focus on the impact of two types of fine sediment supplies, reflecting different watershed-scale processes: 1) pulsed input of fine material (e.g., debris flows and landslides) and 2) chronic input
Progress in Physical Geography: Earth and Environment
Recent work in the undeveloped Rio Murta Basin, located in Chilean Patagonia, identified an evolu... more Recent work in the undeveloped Rio Murta Basin, located in Chilean Patagonia, identified an evolutionary trend in the fluvial system as it progresses toward and away from dynamic equilibrium. A location-for-time-substitution model employed over the longitudinal extent of a 16 km study site assessed the performance of extremal hypotheses in identifying dynamic equilibrium conditions. Numerous extremal hypotheses were successful in identifying the spatial trend, but no means were available to discern differences between them. Thus, this study uses field measurements within the evolutionary trend to propose a new metric for evaluating extremal hypotheses. A thorough review and synthesis of the extremal approach are additionally presented. The new method compares theoretical predictions against field-measured values to determine which extremal hypothesis is most effective in identifying the condition of dynamic equilibrium in a gravel-bed river. Channel width and depth are identified as...
Accurate prediction of pollutant concentrations in a river course is of great importance in envir... more Accurate prediction of pollutant concentrations in a river course is of great importance in environmental management. Mathematical dispersion models are often used to predict the spatial distribution of substances to help achieve these objectives. In practice, these models use a dispersion coefficient as a calibration parameter that is calculated through either expensive field tracer experiments or through empirical equations available in the scientific literature. The latter are based on reach-averaged values obtained from laboratory flumes or simple river reaches, which often show great variability when applied to natural streams. These equations cannot directly account for mixing that relates specifically to spatial fluctuations of channel geometry and complex bed morphology. This study isolated the influence of mixing related to bed morphology and presented a means of calculating a predictive longitudinal mixing equation that directly accounted for pool-riffle sequences. As an e...
Hydrodynamics are a major environmental factor on intertidal rocky shores. Morphological response... more Hydrodynamics are a major environmental factor on intertidal rocky shores. Morphological responses to this factor are expected to strongly influence spatial distribution of species across environmental gradients. We here analysed the shell phenotypic variability of the limpet Fissurella latimarginata using geometric morphometric analysis. The limpets were obtained from a sheltered intertidal coastal area and a wave-exposed environment. To determine whether the shell shape variation of the intertidal molluscs is linked to their resistance to differential intertidal wave exposure, mesocosm studies were developed in a hydraulic flume to explore the effects of hydrodynamic forces on this limpet species. A unidirectional current was used to test the impacts of step-by-step increased current flow velocities for each limpet. The phenotypic variability observed in the populations of F. latimarginata was associated with habitats characterized by contrasting wave exposure. Limpets from expose...
Countries growing rates are directly related to energy production. Therefore, developed and devel... more Countries growing rates are directly related to energy production. Therefore, developed and developing nations are focused on hydropower and dam construction; on the contrary dam removal practices are significantly different among nations, demonstrating the former group a lesser interest on removing structures. Chiles hydropower generation corresponds to 50% of the current grid, having a potential capacity to double the current situation. Thus: ¿What tools can we apply to assess the potential impacts on our rivers?
Supplementary_Materials_V1 for Evaluation of extremal hypotheses in an undeveloped alluvial river... more Supplementary_Materials_V1 for Evaluation of extremal hypotheses in an undeveloped alluvial river by Andrew W Tranmer, Diego Caamaño and Peter Goodwin in Progress in Physical Geography: Earth and Environment
The installation of hydroelectric plants has generated multiple environmental impacts on the worl... more The installation of hydroelectric plants has generated multiple environmental impacts on the world’s river systems. In central Chile, the impacts of hydroelectric reservoir operation have been documented in ecological and hydrologic regime terms. This investigation assesses the changes in channel morphology, vegetation distribution, and flows in the middle section of the Maule River during the period following the start-up of a hydroelectric plant. Changes in fluvial morphology (active area) and land cover are quantified using LANDSAT images, contrasted with a vegetation sampling and flow analysis. The results show a 12% decrease in active areas of the river, indicating a loss of geomorphological diversity. Within the active channel, there was a gradual increase in plant-covered surface area, which reached 159% between 1989 and 2018, mainly due to reductions in water (−61%), active bar (−35%), and bare soil surface areas (−29%). The changes were evident ten years after plant operati...
Modeling the effects of pulsed versus chronic sand inputs on salmonid spawning habitat in a low-g... more Modeling the effects of pulsed versus chronic sand inputs on salmonid spawning habitat in a low-gradient gravel-bed river
Abstract The indeterminate channel problem arises from uncertainty in finding a closure relation ... more Abstract The indeterminate channel problem arises from uncertainty in finding a closure relation for alluvial channels created by self-organizing erosional and depositional processes. Extremal hypotheses have been proposed as one potential approach to closing the system of governing equations for alluvial channels. Many different extremal hypotheses have been presented, but no substantive evidence has been developed to select which hypothesis may be most appropriate for natural alluvial river systems. This paper evaluates the ability of ten extremal hypotheses to identify dynamic equilibrium across a geomorphic gradient in the remote and undeveloped mid-latitude watershed of Rio Murta, Chile. This study (a) introduces extremal hypotheses, (b) describes the field site and geomorphic conditions, and (c) examines which extremal hypotheses are supported by the field data in identifying the evolutionary trend toward dynamic-equilibrium. The extremal hypotheses that identified dynamic equilibrium within the geomorphic gradient in the field are: (1) minimum kinetic energy, (2) minimum specific stream power, (3) maximum friction factor, and (4) maximum total friction factor, which collectively support minimizing kinetic energy of the system.
Progress in Physical Geography: Earth and Environment
Recent work in the undeveloped Rio Murta Basin, located in Chilean Patagonia, identified an evolu... more Recent work in the undeveloped Rio Murta Basin, located in Chilean Patagonia, identified an evolutionary trend in the fluvial system as it progresses toward and away from dynamic equilibrium. A location-for-time-substitution model employed over the longitudinal extent of a 16 km study site assessed the performance of extremal hypotheses in identifying dynamic equilibrium conditions. Numerous extremal hypotheses were successful in identifying the spatial trend, but no means were available to discern differences between them. Thus, this study uses field measurements within the evolutionary trend to propose a new metric for evaluating extremal hypotheses. A thorough review and synthesis of the extremal approach are additionally presented. The new method compares theoretical predictions against field-measured values to determine which extremal hypothesis is most effective in identifying the condition of dynamic equilibrium in a gravel-bed river. Channel width and depth are identified as...
The volume, temporal and caliber of sediment supplied to gravel-bed rivers can have considerable ... more The volume, temporal and caliber of sediment supplied to gravel-bed rivers can have considerable effects on stream characteristics. In particular, fine sediment has critical effects on stream biota. Here, we focus on the impact of two types of fine sediment supplies, reflecting different watershed-scale processes: 1) pulsed input of fine material (e.g., debris flows and landslides) and 2) chronic input
Progress in Physical Geography: Earth and Environment
Recent work in the undeveloped Rio Murta Basin, located in Chilean Patagonia, identified an evolu... more Recent work in the undeveloped Rio Murta Basin, located in Chilean Patagonia, identified an evolutionary trend in the fluvial system as it progresses toward and away from dynamic equilibrium. A location-for-time-substitution model employed over the longitudinal extent of a 16 km study site assessed the performance of extremal hypotheses in identifying dynamic equilibrium conditions. Numerous extremal hypotheses were successful in identifying the spatial trend, but no means were available to discern differences between them. Thus, this study uses field measurements within the evolutionary trend to propose a new metric for evaluating extremal hypotheses. A thorough review and synthesis of the extremal approach are additionally presented. The new method compares theoretical predictions against field-measured values to determine which extremal hypothesis is most effective in identifying the condition of dynamic equilibrium in a gravel-bed river. Channel width and depth are identified as...
Accurate prediction of pollutant concentrations in a river course is of great importance in envir... more Accurate prediction of pollutant concentrations in a river course is of great importance in environmental management. Mathematical dispersion models are often used to predict the spatial distribution of substances to help achieve these objectives. In practice, these models use a dispersion coefficient as a calibration parameter that is calculated through either expensive field tracer experiments or through empirical equations available in the scientific literature. The latter are based on reach-averaged values obtained from laboratory flumes or simple river reaches, which often show great variability when applied to natural streams. These equations cannot directly account for mixing that relates specifically to spatial fluctuations of channel geometry and complex bed morphology. This study isolated the influence of mixing related to bed morphology and presented a means of calculating a predictive longitudinal mixing equation that directly accounted for pool-riffle sequences. As an e...
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Papers by Diego Caamano