Streamflow Regulation Research Articles

Sustaining high-value salmonid populations in regulated rivers: Insights from individual-based modelling of brown trout and Atlantic salmon

To combat climate change, societal pressure to develop fossil-free hydroelectricity is growing. There is a great need, however, for environmental assessment tools that can predict the effects of streamflow regulation on biodiversity in hydropower-regulated rivers. Ecological modelling lets practitioners: 1) set broad bounds on population-level responses of key species and 2) identify knowledge gaps and prioritize research needs. Individual-based models (IBMs) are powerful tools for assessing relative benefits of alternative management actions, and therefore help to develop more sustainable hydropower solutions. We applied the inSALMO 7.3-SD IBM for populations of brown trout (Salmo trutta) and Atlantic salmon (S. salar) in the lower Gullspång River, Sweden. We simulated the effects of various minimum hydropeaking flow releases (from 9 to 21 m3/s) on outmigration production. We found that the number of age-1 outmigrants of both species decreased with increasing minimum flow release of the hydropeaking scenarios. The number of age-2 trout outmigrants did not change considerably with increasing the minimum release, but decreased sharply at the highest flow. The most age-2 salmon outmigrants were produced by flow scenarios with minimum releases of 15 and 18 m3/s. The model predicts, therefore, varying species- and life stage-specific effects of flow regulation. Moreover, increased flow caused juveniles to stay in the river longer and outmigrate at larger size, which exposes them to simulated predation longer but could increase post-outmigration survival. By providing insights into mechanisms driving population dynamics, IBMs can help promote the sustainability of high-conservation-value fish species.

СОВРЕМЕННОЕ РАСПРЕДЕЛЕНИЕ СТОКА В ДЕЛЬТЕ ВОЛГИ: АНАЛИЗ И МОДЕЛИРОВАНИЕ

The Volga delta is a large, dynamically changing water object. Its regime is determined by both natural water balance components and artificial streamflow regulation by the Volga hydroelectric power plant. The paper provides a brief overview of the studies of the Volga delta delta water regime and runoff distribution among the Volga delta branches, including those dealing with the runoff parametrization and computation. It also discusses the works on modeling the runoff distribution. The HEC-RAS software has been used to develop a one-dimensional hydrodynamic model of the Volga delta from its top (the Volga/Verkhnelebyazh’e gauging station) to the Astrakhan-Krasnyi Yar gauge line. The model calibration has been performed using in situ measurements in the delta in 2019 and network gauging data, the validation has been carried out based on the network gauging data for 2015, 2017, and 2018. Modeling results have shown that the contribution of runoff flowing to the Buzan branch source has slightly increased as compared to the period of 2001-2012.

Impacts of small and medium-sized reservoirs on streamflow in two basins of Southeast China, using a hydrological model to separate influences of multiple drivers

Study regionSoutheast coast of China Study focusThe reservoirs in southeast coast of China are mostly small due to the limitations of terrain. In order to analyze the impact of these densely distributed small and medium-sized reservoirs (SMRs) with lacking observation and operational data on runoff, this paper uses a hydrological model & scenario simulation method to separate the impacts of climate variability (CV), land use change (LUC) and SMRs group change on streamflow variation in two river basins of Southeast China. New hydrological insights for the region(1) The streamflow of two basins has changed greatly, with CV and SMRs change being the main influencing factors, while the impact of LUC was relatively small. The contribution rates of CV to the annual runoff change of three hydrological stations in two river basins were 90.19%, 61.75% and 26.64%; Contribution rates of SMRs changes were 9.34%, 37.24% and 71.04%, correspondingly. (2) The regulation of streamflow by SMRs changes led to a decrease in both annual and monthly runoff, which was due to the fact that the main functions of SMRs in this region are agricultural irrigation and domestic water supply. (3) The three-factor separation method based on hydrological modeling, which separated the cumulative effects of SMRs in the form of SMRs group, would be valuable for the study and management of watersheds with numerous SMRs and lack of observation and operational data.

Mesohabitat and macroecological correlates for blue sucker (Cycleptus elongatus) occurrence in regulated rivers

AbstractBlue sucker (Cycleptus elongatus) populations occur in the Mississippi River and Gulf of Mexico drainages of North America and are negatively affected by habitat fragmentation and flow regime alteration caused by dams. During fish assemblage surveys in August of 2022, we collected five juvenile blue suckers (312–428 mm total length) in the Angelina River upstream of Sam Rayburn Reservoir in East Texas (46,335 ha surface area) where the occurrence of the species was previously unconfirmed. Given this unexpected finding, we (1) analyzed mesohabitat associations to compare habitats we sampled with reports in the literature and (2) reviewed blue sucker occurrences in state, national, and global databases across historical (1950–1980) and contemporary (1981–2022) time periods to assess occurrence across gradients of habitat fragmentation and streamflow regulation. The blue sucker population in the Angelina River upstream of Sam Rayburn Reservoir was previously unconfirmed but is within the native range. Mesohabitats occupied by blue suckers were consistent with literature reports, including fast velocity, shallow depth, and coarse substrates. The low degree of regulation (19% of natural runoff stored by upstream reservoirs) and a high degree of habitat connectivity (287 rkm of unfragmented mainstem habitat) for the Angelina River upstream of Sam Rayburn Reservoir matched range‐wide patterns of persistence within relatively intact (unfragmented and unregulated) or remnant (fragmented but unregulated) riverscapes. Our review reveals that blue sucker populations might persist (1) in remnant river fragments where local habitat conditions are appropriate and (2) where effects of habitat fragmentation and flow regulation are not coupled.

Effects of Vegetation Restoration on the Hydrological Regimes of the Chinese Loess Plateau: A Comparative Analysis of Forested and Less-Forested Catchments

Large-scale vegetation restoration can significantly affect catchment hydrology. Assessing the impact of vegetation restoration on hydrological regimes is important for water resource management. We chose three less-forested catchments (LFCs, forested area <30%) undergoing major vegetation restoration, i.e., Wuqi, Zhidan, and Liujiahe, and two forested reference catchments (FCs, forested area >77%) that have had secondary forests for more than 150 years, i.e., Zhangcunyi and Huangling, of the Beiluo River basin located in the Loess Plateau (LP) to compare and analyze the stationary and variation characteristics of streamflow and its components from 1958 to 2019. Results show that the mean annual streamflows were 25.07~34.21 and 21.62~48.02 mm in the LFCs and FCs, respectively. The mean streamflow in the LFCs decreased by 50% on average from before the year 2000 to after. The decreasing trend of high flows and increasing trend of low flows is represented in the daily flow duration curves of the LFCs. The result of baseflow separation shows that the average percentages of baseflow in the streamflow were 31.89~43.36% in the LFCs and 58.23~60.14% in the FCs. The Mann–Kendall tests showed significant decreasing trends in annual streamflow (−0.27~−0.70 mm/a) and stormflow (−0.29~−0.64 mm/a) in the LFCs from 1958 to 2019, while the baseflow exhibited increasing trends except for in the Zhidan catchment. The seasonal streamflow and stormflow showed significant decreasing trends in the summer and non-flood season, while the winter and non-flood season’s baseflow increased in LFCs. In FCs, however, the streamflow and its components showed only slight fluctuations over the study period in annual trends, decadal variability, and seasonal trends over the study period, suggesting that FCs have stable hydrological regimes. These results indicate that 20 years of large-scale vegetation restoration greatly influenced hydrological regimes by reducing stormflow and increasing baseflow, and played an important role in streamflow regulation. Conversely, areas with well-preserved vegetation can effectively mitigate the effects of weather and other factors on runoff with stable hydrological regimes. This study can help vegetation restoration and water resource management on the LP.

Assessing Probability Characteristics of Reservoir Operation Using Bayesian Technology

This study explores the use of Bayes' theorem to determine the probability characteristics of reservoir operation, specifically in cases where the reservoir capacity is exceeded or sustained within its active storage capacity. The investigation focuses on moments of streamflow increase during the spring flood and water shortage in the fall. The study aims to develop methods for regulating reservoir runoff using Bayesian technology, with specific tasks including developing a calculation algorithm to estimate the probabilistic characteristics of reservoir operation based on the Bayes formula with a seasonal division of the water management year, identi-fying the necessary probabilistic characteristics of reservoir filling and water recovery, and solving the inverse problem using the Bayes formula to determine the required initial filling at given values of the reservoir filling and its probability by the end of the calculated time interval. The study's relevance is rooted in the need to determine the probability characteristics of reservoir filling and water discharge to consumers during streamflow regulation.

A Jump Ornstein–Uhlenbeck Bridge Based on Energy-Optimal Control and Its Self-Exciting Extension

We study a version of the Ornstein-Uhlenbeck bridge driven by a spectrally-positive subordinator. Our formulation is based on a Linear-Quadratic control subject to a singular terminal condition. The Ornstein-Uhlenbeck bridge, we develop, is written as a limit of the obtained optimally controlled processes, and is shown to admit an explicit expression. Its extension with self-excitement is also considered. The terminal condition is confirmed to be satisfied by the obtained process both analytically and numerically. The methods are also applied to a streamflow regulation problem using a real-life dataset.

Hydrologic impacts of cascading reservoirs in the middle and lower Hanjiang River basin under climate variability and land use change

Study regionMiddle and lower Hanjiang River (MLHR) basin, China. Study focusChanges in streamflow are often due to intertwined factors like climatic variability, land use change, and hydraulic constructions, whose relative impact is however poorly understood. In this study, we disentangled these effects by comparing real data and modelled scenarios of catchment behaviour. Modelled scenarios employ the soil and water assessment tool (SWAT), whereas the scenario comparison uses the Indicators of Hydrologic Alteration (IHA). New hydrological insights for the regionOur analyses show that (1) watershed inlet was the major factor altered the streamflow regime at the watershed outlet, which pointed us to consider only the relative catchment contribution in further analyses. (2) Climate variability was the main driver of the net changes in natural hydrological regime, which downplayed the effect of land use change on streamflow variability. (3) The streamflow regulation associated to the progressive increase in reservoirs and their operation significantly altered the flow pattern, causing a general decrease in average streamflow, an attenuation of extreme events indicators, and an alteration of the pulse pattern with more frequent but shorter pulses. (4) The average water withdrawals at MLHR were estimated, which were 8.03 × 109 m3/year. Overall, this research provides a path to assess the hydrologic impact of cascading reservoirs at the basin level under climate variability and land use change elsewhere.

Where and When Does Streamflow Regulation Significantly Affect Climate Change Outcomes in the Columbia River Basin?

AbstractThe Columbia River basin is a large transboundary basin located in the Pacific Northwest. The basin spans seven US states and one Canadian province, encompassing a diverse range of hydroclimates. Strong seasonality and complex topography are projected to give rise to spatially heterogeneous climate effects on unregulated streamflow. The basin's water resources are economically critical, and regulation across the domain is extensive. Many sensitivity studies have investigated climate impacts on the basin's naturalized hydrology; however, few have considered the large role of regulation. This study investigates where and when regulation affects projected changes in streamflow by comparing climate outcomes across 80‐member ensembles of unregulated and regulated streamflow projections at 75 sites across the basin. Unregulated streamflow projections are taken from an existing data set of climate projections derived from Coupled Model Intercomparison Project version 5 Global Climate Models. Regulated streamflow projections were modeled by the US Army Corps of Engineers and the US Bureau of Reclamation by using these unregulated flows as input to hydro‐regulation models that simulate operations based on current and historical water demands. Regulation dampens shifts in winter and summer streamflow volumes. Regulation generally attenuates changes in cool‐season high flow extremes but amplifies shifts in warm‐season and annual high flow extremes at historically snow‐dominant headwater reservoirs. Regulation reduces dry‐season low flow changes in headwater tributaries where regulation is large but elsewhere has little effect on changes in low flows. Results highlight the importance of accounting for water management in climate sensitivity analysis particularly in snow‐dominant basins.

Changes of streamflow regulation in an Andean watershed with shrinking glaciers: implications for water security

ABSTRACT Glaciated Andean mountains have experienced several decades of shrinkage in their transition to non-glaciated regimes. This study analyses the period of hydrologic transition from 1956 to 2020 in a watershed of the Sierra Nevada del Cocuy (SNC), which is the most extensive remaining tropical glacier in Colombia. Using ground hydrometeorological data, remote sensing products, a metric of extreme flow regulation, and decadal flow duration curves, the study shows how the combined effect of continuous glacier shrinkage, highly variable precipitation regimes and increasing human extractions have altered the hydrological capacity of the watershed to regulate high, low, and mean flows. The alteration is noticeable since the 2000s, when communities have effectively benefited from the surplus of baseflow provided by the shrinking glacier to the limit, creating an unsustainable dependency with potential restrictions of use in the short run and major implications for water security of humans and the environment in the forthcoming decades.

Climate Adaptation Needs to Reduce Water Scarcity Vulnerability in the Tagus River Basin

In southern Europe, climate change is expected to aggravate water scarcity conditions and challenge current water management practices. The present paper evaluates the impacts of climate change in the highly regulated Tagus River basin and assesses various adaptation options, quantifying the effort needed to maintain the ability to sustain current water uses. A water management and allocation model covering surface and groundwater resources is used to evaluate available and renewable water resources for different climate scenarios. Additionally, the Water Exploitation Index Plus (WEI+) and water supply reliability criteria are used to quantify water scarcity and the ability to satisfy water demands, respectively. The results show that climate change will significantly change the stream flow regime and reduce water availability in the Tagus River basin, but the existing reservoir infrastructure will alleviate some of these impacts, especially in the dry half-year. Until the end of the century, water scarcity levels, measured by annual WEI+, are expected to increase in the Tagus River basin from 0.46 to 0.52 or 0.62, respectively under two Representative Concentration Pathways (RCP 4.5 or RCP 8.5). The benefits of streamflow regulation vary with the hydrological regimen, the current degree of water use and the role of groundwater resources to meet demand. The benefits of streamflow regulation are also dependent on the environmental flow requirements that will be adopted in the future. A reduction of water consumption for irrigation by 25% to 40% will significantly improve the Tagus River system performance and maintain the current scarcity situation in the future, under the expected scenarios of climate change.

Technologies for the study of hydropeaking impacts on fish populations: Applications, advantages, outcomes, and future developments

AbstractDam construction and streamflow regulation are increasing throughout the world, with impacts in impounded aquatic ecosystems. Hydropower dams, some of them causing a phenomenon called “hydropeaking” during their operation, are known for having a variety of impacts on downstream aquatic biota, particularly fish, and respective habitat. This can result in significant changes, from the community (e.g., fish assemblage structure) to the individual level (e.g., physiological and behavioural adjustments). Researchers and managers involved in the assessment of hydropeaking impacts must be resourceful and use methods that allow their precise evaluation, from large to fine‐scale habitat and biological responses. In the last decades, technological advances allowed for the development of techniques and instrumentations that are increasingly being used in hydropeaking impact and mitigation assessments. This paper aims to provide a review, to researchers and managers interested in this field, of some of the most innovative methods and techniques, involving technology, that are available to study hydropeaking effects on downstream ecosystem, particularly from a fish perspective. We discuss the fundamentals behind such techniques, their advantages, and disadvantages, while also providing practical examples of their application and of the type of results that can be obtained. We finish by discussing some of the shortcomings of these methods and how related technology can evolve to solve current limitations.

Comparison of Machine Learning Models Performance on Simulating Reservoir Outflow: A Case Study of Two Reservoirs in Illinois, U.S.A.

ABSTRACTReservoir outflow is an important variable for understanding hydrological processes and water resource management. Natural streamflow variation, in addition to the streamflow regulation provided by dams and reservoirs, can make streamflow difficult to understand and predict. This makes them a challenge to accurately simulate hydrologic processes at a daily scale. In this study, three Machine Learning (ML) algorithms, Random Forest (RF), Support Vector Machine (SVM), and Artificial Neural Network (ANN), were examined and compared to model reservoir outflow. Past, current, and future hydrologic and meteorological data were used as model inputs, and the outflow of next day was used as prediction. Simulation results demonstrated that all three models can reasonably simulate reservoir outflow. For Carlyle Lake, the coefficient of determination and Nash–Sutcliffe efficiency were each close to one for the three models. The coefficient of determination, relative mean bias, and root mean square error indicated that the SVM performed better than the RF and ANN, but the SVM output displayed a larger relative mean bias than that from RF and ANN. For Lake Shelbyville, the ANN model performed better than RF and SVM when considering the coefficient of determination, Nash–Sutcliffe efficiency, relative mean bias, and root mean square error. The study results demonstrate that the three ML algorithms (RF, SVM, and ANN) are all promising tools for simulating reservoir outflow. Both the accuracy and efficacy of the three ML algorithms are considered to support practitioners in planning reservoir management.

Productivity of riparian Populus forests: Satellite assessment along a prairie river with an environmental flow regime

AbstractIn semiarid regions, the growth and survival of cottonwoods (riparian Populus species) depend on river water supplementing the limited precipitation. Indicators of growth and productivity are needed to assess how altered streamflow regimes on regulated rivers impact cottonwood trees and the riparian forest ecosystems they support. We used satellite imagery from the Landsat program to make historical (1984–2020) assessments of ecosystem productivity in a riparian cottonwood forest along a regulated prairie river in southern Alberta, Canada, with an environmental flow regime that increased the minimum flows implemented in 1993. A version of the near‐infrared reflectance of vegetation scaled with incoming sunlight (NIRvP) was calculated from Landsat images to provide a proxy for primary production. Near‐infrared reflectance of vegetation scaled with incoming sunlight was correlated strongly with gross primary production measurements from eddy covariance and basal area increment measurements from tree ring analyses, supporting its use as a practical proxy. The lowest NIRvP values occurred in drought years with low flows and dry weather during the growing season, while the highest values occurred in wet years with high flows, including floods. Across all years, NIRvP was positively correlated with streamflow and a weather‐driven soil moisture index. This indicated that ecosystem productivity was limited by water supply, which is sourced from river water and local precipitation. Subsequently, cottonwood forests in this region would be vulnerable to drought from declines in streamflow, due to climatic variations or human water withdrawals, and reductions in shallow soil moisture from limited local precipitation. This satellite proxy should be broadly applicable and can provide a diagnostic indicator for assessing riparian forest health and responses to varying weather, changing climate, and streamflow regulation.

Approaches to cost-effectiveness of payments for tree planting and forest management for water quality services

The evaluation of the cost-effectiveness of Payments for ecosystem services (PES) in fostering positive environmental outcomes has been central to the scientific debate on their implementation. PES cost-effectiveness can be affected by a myriad of environmental, institutional and socio-economic factors operating at different spatial and temporal scales. Moreover, it can be affected by synergies and trade-offs in the provision of ecosystem services (ES). Planting trees is increasingly considered an effective measure to provide water-related ES. It can enhance watershed services such as nutrient retention, erosion control, stream flow regulation, protection against extreme events (e.g., floods and landslides), and lead to a permanent change in land use, replacing agricultural activities that give rise to diffuse pollution. Very few studies currently exist on the cost-effectiveness of tree planting for water quality benefits PES schemes in Europe. Including both review and research elements, this paper highlights challenges in undertaking such assessments. It develops a conceptual framework to help underpin future studies, with its application to three case studies in Denmark explored. Particular attention is given to the estimation of environmental effectiveness in the provision of water quality services and the importance of co-benefits. In the case where we exclude co-benefits from the analysis, the financial cost-effectiveness is always above zero, with central estimates (without discounting environmental improvements) of €10/Kg N, and €0.36 to €0.50/mg pesticide. Once co-benefits are accounted for, however, the social cost-effectiveness is negative (except for under the low estimates) as the value of the co-benefits exceeds the costs, with central estimates of -€28/Kg N, and -€0.34 to -€0.23/mg pesticide. The paper discusses the implications and lessons for PES cost-effectiveness analysis, and identifies research gaps. Increased knowledge of forest water benefits and the cost-effectiveness of woodlands for water schemes would help underpin future incentives to enhance the provision of these ES.

Reservoirs regulate the relationship between hydrological drought recovery water and drought characteristics

Regulation of streamflow by large reservoirs alters the characteristics of hydrological drought. However, few studies have focused on the impacts of regulation on the water required (WR) for hydrological drought recovery, nor on the response relationship between WR and drought characteristics (i.e., duration and severity). Therefore, we proposed a comparative approach that integrates reconstructing unregulated streamflow and a drought identification method using variable threshold levels (VTLs) to evaluate the impacts. Long-term (>40 years) observational datasets for streamflow at a hydrometric station and inflow and outflow at multiple large reservoirs in the Dongjiang River Basin were used. Using VTLs that accounted for seasonal differences in hydrological processes, our method performed well in identifying historical hydrological droughts and their characteristics in the study area. The WR mainly depended on drought severity rather than drought duration and there was a clear nonlinear response relationship (i.e., power function) between WR and drought severity. The performance indices (i.e., R2 = 0.92, NSE = 0.97, PBIAS = 13.57%) indicated that the optimal nonlinear function model could accurately simulate the WR of hydrological drought events. Large reservoirs reduce the frequency of hydrological droughts, shorten drought duration, and reduce drought severity by storing water in the flood season and releasing it in the dry season. The presence of reservoirs shifted the relationship between WR and drought severity from linear to nonlinear. These findings showed that the proposed methodology can help us to optimize the management of water resources for drought prevention and disaster reduction under changing environments.

Eucalyptus tree stockings effect on water balance and use efficiency in subtropical sandy soil

Eucalyptus tree stocking can be adjusted to increase, depending on purpose, cellulose, timber or bioenergy production, but the effect of stocking on ecosystem water balance is still understudied. Studies on soil and catchment hydrology and forest management, encompassing distinct climatic years, are needed for understudied ecosystems to improve water use efficiency and streamflow regulation, and thus bridging forestry and ecosystem processes. For different Eucalyptus dunnii stockings, we measured rainfall dynamics to quantify rainfall partitioning, soil water balance, and eucalyptus water use efficiency in a sandy soil. Total rainfall, throughfall, stemflow, canopy interception, evapotranspiration, tree growth, and water use efficiency were evaluated over a 1-year study period (5th to 6th years after planting), in low (LS: 816 trees ha−1), medium (M: 1,633 trees ha−1), medium–high (MH: 3,265 trees ha−1), and high tree stockings (HS: 6,568 trees ha−1). Tree stocking had no clear relation with the partitioning of annual rainfall (P, 2583 mm) into canopy interception (34–37% of P) and effective rainfall (63–66% of P). By increasing tree stocking from 816 to 6,568 trees ha−1, throughfall decreased from 62 to 53% of P, and stemflow increased from 2.1 to 12.7% of P. Estimated deep drainage was <0.16% of P, even though the annual rainfall was almost double of historical rainfall and surface runoff was only 5.7% of P. Thus, groundwater recharge in Eucalyptus plantation may be potentially low even with high rainfall in a soil with high infiltration and low slope (about 4%). Cumulative evapotranspiration varied between 1304 and 1438 mm (50–56% of P), highest for high tree stocking, whereas daily evapotranspiration rates varied between 0.8- and 11.7-mm d−1. From the 5th to the 6th year after planting, the individual wood production varied from 4.9 (HS) to 51.8 kg−1 tree (LS), and stand wood production varied from 27.1 (MHS) to 42.2 (LS) Mg ha−1 yr−1. Water use efficiency varied from 2.1 to 3.1 g L−1, respectively for MHS and LS. Industrial eucalyptus planted in sandy soils at high stocking for energy production may overuse stored water, affecting long-term forest sustainability. Therefore, the challenge is decreasing evaporation from soil and canopy and increasing green-water use efficiency, while generating surface runoff for ecological flows and groundwater recharge (blue water flow).

Using Engineering With Nature® (EWN® ) principles to manage erosion of watersheds damaged by large-scale wildfires.

The US Army Corps of Engineers (USACE) manages hundreds of reservoirs and thousands of miles of navigation channels that provide invaluable flood control, commercial transport of materials, water supply, recreation, and stream flow regulation. This capability is being threatened by the continued occurrence of large-scale wildfires across the western United States. The wildfires damage watersheds in part by denuding landscapes, reducing infiltration rates, and increasing runoff rates, thereby dramatically increasing the potential for the erosion of denuded slopes, destabilizing stream channels, increasing the infilling potential of reservoirs and, hence, reducing their capacity. The increased erosion rates highlight the need to develop innovative solutions to reduce erosion of watersheds laid bare after wildfires engulf the area. The Santa Clara Pueblo in northern New Mexico extends from the top of the eastern Jemez Mountains to the floodplains of the Rio Grande River. The Pueblo designed and constructed thousands of structures built from natural materials, consistent with Engineering With Nature (EWN) principles for erosion control incorporating low-cost and readily available materials such as logs, mulch, vegetation, and local rock to stabilize highly erodible parts of the watershed. The watersheds where these natural structures were constructed were monitored after construction to assess their effectiveness, guiding a series of recommendations for broader implementation. As part of a continued emphasis on updating USACE engineering guidance, research, and development, funding has been focused on developing sustainable and resilient project designs using natural materials like those implemented by the Santa Clara Pueblo. This paper focuses on the innovative EWN-based watershed stabilization practices that were implemented in the upper section of this wildfire affected canyon and tributary streams. Recommendations for future implementation based on lessons learned from this project are also provided. Integr Environ Assess Manag 2021;17:1194-1202. Published 2021. This article is a US Government work and is in the public domain in the USA.

Bottomland hardwood forest growth and stress response to hydroclimatic variation: evidence from dendrochronology and tree ring Δ&amp;lt;sup&amp;gt;13&amp;lt;/sup&amp;gt;C values

Abstract. Wetland forests around the world have been reduced to a small proportion of their original expanse due to changing climatic conditions and intensification of human land use activities. As a case in point, the Columbia bottomland hardwood forests along the Brazos–Colorado coastal basin on the Gulf coast of Texas are currently threatened by an increasingly erratic hydroclimate in the form of both extreme floods and droughts and by urban expansion. In this study, we use dendrochronology and tree ring carbon isotopes to understand the effect of changing hydroclimatic conditions on the functional attributes of these forests. We examined the tree rings of Quercus nigra at four sites within the Columbia bottomlands, of which one site experiences frequent and prolonged flooding, while the other three are less flood prone. The objectives of this study were to (i) understand the impact of hydroclimatic variation on radial growth, using tree ring width analysis, (ii) assess the magnitude of physiological stress inflicted by extreme hydroclimatic conditions, using tree ring Δ13C measurements as a proxy, and (iii) evaluate the relationship between tree ring width and Δ13C values. Radial growth across the landscape was influenced most strongly by the midgrowing season climate, while the early growing season climate had the strongest effect on Δ13C. Growth inhibition was minimal, and tree ring Δ13C values were not affected in trees at the wetter site under extreme hydrological conditions such as droughts or floods. In addition, trees at the wet site were less sensitive to precipitation and showed no response to higher temperatures. In contrast, trees at the three drier sites experienced growth inhibition and had lower tree ring Δ13C values during dry periods. Our results indicate more favorable growing conditions and lower stress in trees growing under wetter hydrological conditions. Management and conservation strategies dependent on site-specific conditions are critical for the health of these wetland forests under a rapidly changing hydroclimate. This study provides the first dendrochronological baseline for this region and a better understanding of favorable conditions for the growth and health of these forests, which can assist in management decisions such as streamflow regulation and conservation plans.

Regionalização da curva de regularização de vazão da bacia do rio Juruena

A regularização de vazão é essencial quando a demanda de água é maior que a vazão mínima. Isso torna necessária a acumulação dos excessos para atender períodos cuja disponibilidade hídrica natural é menor que demanda de captação. Nesse contexto, o objetivo do trabalho foi regionalizar a curva de regularização de vazões para a bacia do rio Juruena de forma a subsidiar projetos de outorga e dimensionamento de reservatórios. Foi gerada curva adimensional de regularização de vazão para sete seções de monitoramento de vazão da bacia. Em seguida foi ajustado o modelo potencial aos dados das curvas de forma a regionaliza-las. As equações de regionalização propostas possuem precisão e acurácia e poderão embasar projetos de regularização de vazão para irrigação, abastecimento público e geração de energia elétrica.