Flow Regime Characteristics Research Articles

Transient Flow of a Horizontal Well with Multiple Fracture Wings in Coalbed Methane Reservoirs

Horizontal wells with multi-stage fractures have been widely used to improve coalbed methane (CBM) production from coalbed methane reservoirs. The main focus of this work is to establish a new semi-analytical method in the Laplace domain and investigate the transient pressure behavior in coalbed methane reservoirs. With the new semi-analytical method, flow regimes of a multi-fractured horizontal well in coalbed methane reservoirs were identified. In addition, the sensitivities of fracture conductivity, diffusion model, storability ratio, inter-porosity flow coefficient, adsorption index, fracture spacing, fracture asymmetry, non-planar angle, and wellbore storage were studied. Results indicate that six characteristic flow regimes can be identified for multi-fractured horizontal wells in coalbed methane reservoirs, which are bilinear flow, first linear flow, desorption-diffusion flow, first pseudo-radial flow, second linear flow, and second pseudo-radial flow. Furthermore, the sensitivity analysis shows that the early flow is mainly determined by the fracture conductivity, the asymmetry factor, the non-planar angle, and the wellbore storage; while the desorption-diffusion flow regime is mainly influenced by the diffusion model, the storability ratio, the inter-porosity flow coefficient, the adsorption index, and the fracture spacing. Our work can provide a deep insight into the fluid flow mechanism of multi-fractured horizontal wells in coalbed methane reservoirs.

On non-axisymmetric flow structures of graphene suspensions in Taylor–Couette reactors

The quality of graphene sheets significantly depends on the degree of oxidation of graphite and the methods used for synthesis. Therefore, selecting an eco-friendly and cost-effective process is an important step in order to increase the oxidation level. The latest studies show that Taylor–Couette reactors are one of the best options to improve the oxidation level of graphite. Graphene suspensions show shear-thinning behavior, and the emergent flow structures in TC flows significantly influence the oxidation degree. In this study, we investigated the flow patterns of shear-thinning fluids in a TC reactor. The effect of radius ratio, power-law index and the rotating direction of the cylinders on the flow patterns and their critical values is studied experimentally in a Taylor–Couette flow that occurred between concentric cylinders. The Reynolds numbers defined with the wall shear viscosities (Rei and Reo) are used for evaluating the critical conditions of various flow structures. The results demonstrate that fluid properties and radius ratio may have significant destabilization effects in forming non-axisymmetric flow patterns and change their critical values. The characteristics of various flow regimes are altered substantially with increasing inner cylinder speed. A strong influence of the rotation direction of the outer cylinder on flow structures and their critical Reynolds numbers has also been revealed in this study. The obtained results also provide a deeper understanding of fluid–suspension interactions in TC reactors. These new findings will help in designing and developing more efficient TC reactors to be used in synthesizing high-quality graphene products.

Transformation of the Flow Regime of a Large Allochthonous River in Central Europe—An Example of the Vistula River in Poland

Identification of river flow regime and its possible changes caused by natural factors or human activity is one of major issues in modern hydrology. In such studies different approaches and different indicators can be used. The aim of this study is to determine changes in flow regime of the largest river in Poland—the Vistula, using new, more objectified coefficients and indices, based on data recorded in 22 gauges on the Vistula mainstream and 38 gauges on its tributaries in the multi-year period 1971–2010. The paper consists of three main parts: in the first part, in order to recognize changes in the flow regime characteristics along the Vistula, data from gauges located on the river mainstream were analyzed with the help of the theory of entropy. In the second part gauging stations on the Vistula mainstream and its tributaries were grouped; values of the newly introduced pentadic Pardé’s coefficient of flow (discharge) (PPC) were taken as the grouping criterion. In the third part of the study a novel method of determining river regime characteristics was applied: through the recognition of the temporal structure of hydrological phenomena and their changes in the annual cycle sequences of hydrological periods (characteristic phases of the hydrological cycle) on the Vistula River mainstream and its tributaries were identified and their occurrence in the yearly cycle was discussed. Based on the detected changes of the 73-pentad Pardé’s coefficients of flow four main types of rivers were distinguished. Transformation of the flow regime was reflected in the identified different sequences of hydrological periods in the average annual cycle. It was found that while transformation of the Vistula River regime occurred along its whole course, the most frequent changes were detected in its upper, mountainous reaches, under the influence of the flow characteristics of its tributaries. This allowed the Vistula to be considered the allochthonous river. These findings are interesting not only from a theoretical point of view, but they also can be valuable to stakeholders in the field of the Vistula River basin water management and hydrological forecasting, including flood protection, which has recently become a matter of growing concern due to the observed effects of climate change and human impact.

Ice in reservoirs and regulated rivers

ABSTRACT In a river with seasonal ice covers, river ice effects must be considered in the design and operation of water control structures such as dams, barrages, and spillways. The regulation of flow and the water levels of rivers and reservoirs have several hydrological, socio-economic, and ecological effects. Regulation alters river-ice regimes by modifying the temporal and spatial characteristics of flow, water level, and thermal regimes in a watercourse. Removal of a water control structure and reservoir can eliminate some problems, but create new problems in areas where environmental or development conditions have changed. Therefore, thorough review of proposals to regulate (or remove regulation on) a river with seasonal ice covers is necessary. The effects of regulation on ice conditions and vice-versa are reviewed in this paper. Although considerable progress has been made during recent years, adequate understanding of the effects of river-ice interaction with structures and the effect of regulation on geomorphology, people, and aquatic habitat requires additional research.

Review of flow regime in CFB standpipe and circulation rate measurement

The classification and characteristics of flow regimes in a circulating fluidized bed standpipe were briefly described. Based on the flow characteristics, several measuring methods of circulating flow rate in standpipe were introduced, including accumulation method, time-of-descent measurements, particle motion detection method, flowmeter method, and correlation method. Advantages and disadvantages of these methods were compared. It can be seen that at present, all measurement methods have some defects, which need to be further studied and improved.

Effects of wall superheat and mass flux on flow film boiling in cryogenic chilldown process

Chilldown process is usually the initial operation for storing and transporting cryogenic fluids. During this process, film boiling is of great importance in terms of the large time span. In this research, a numerical model was built to study the flow regime and heat transfer characteristics of the film boiling with cryogenic fluids. An algebraic interface area density framework was coupled in the model to calculate the drag force at the liquid-gas interface. Accordingly, the effects of wall superheat and mass flow rate on heat flux and film thickness were investigated. Furthermore, the variance analysis method was employed to evaluate the weight of the effects of superheat and inlet mass flow and their coupling effect on the heat transfer coefficient. The results reveal that the wall superheat effect prevails over the mass flux effect on the heat transfer coefficient. Moreover, the two factors have a relatively weak coupling impact on the heat transfer coefficient. Finally, the features of pressure drop in the tube were further analyzed.

Investigation of flow-regime characteristics in a sloshing pool with mixed-size solid particles

Abstract To ascertain the characteristics of pool sloshing behavior that might be encountered during a core disruptive accident of sodium-cooled fast reactors, in our earlier work several series of experiments were conducted under various scenarios including the condition with mono-sized solid particles. It is found that under the particle-bed condition, three typical flow regimes (namely the bubble-impulsion dominant regime, the transitional regime and the bed-inertia dominant regime) could be identified and a flow-regime model (base model) has been even successfully established to estimate the regime transition. In this study, aimed to further understand this behavior at more realistic particle-bed conditions, a series of simulated experiments is newly carried out using mixed-size particles. Through analyses, it is verified that for present scenario, by applying the area mean diameter, our previously-developed base model can provide the most appropriate predictive results among the various effective diameters. To predict the regime transition with a form of extension scheme, a correction factor which is based on the volume-mean diameter and the degree of convergence in particle-size distribution is suggested and validated. The conducted analyses in this work also indicate that under certain conditions, the potential separation between different particle components might exist during the sloshing process.

Multi-directional flow dynamics shape groundwater quality in sloping bedrock strata

Multi-directional fluid flow and transport dynamics as intrinsic characteristics of hillslope flow regimes can strongly contribute to the quality evolution of groundwater resources and compartmentalization of subsurface ecosystems. However, their extent and importance in topographic highs (groundwater recharge areas) is typically less investigated, because productive groundwater bodies and thus monitoring activities are frequently lacking. In the Hainich Critical Zone Exploratory, we explored the hydrogeological functioning of the widely distributed setting of thin-bedded, alternating mixed carbonate-/siliciclastic bedrock, by using basic environmental timeseries. Up to 8-year records of weather parameters, ground temperatures, multi-depth hydraulic heads, and non-conservative tracers, were exploited applying a scheme for the exploratory analysis of dis-/continuous groundwater quality data. We identified transient, multi-directional flow dynamics, comprising fluctuating perched groundwater, localized recharge and groundwater mounding in the aeration zone that modify and partly reverse flow patterns in the phreatic zone. This interplay of flow dynamics within the hillslope aeration and phreatic zone causes significant re-distribution (e.g. oxygen, nitrate) that even overcome the “protective cover” of thick argillaceous strata by supplying surface-sourced substances to deep groundwater resources. As a factor for ecosystem compartmentalization, our results further suggest to carefully consider the hillslope multi-directional flow and matter exchange in biogeochemical models, as well as in resource protection and groundwater management practices.

The hydroelastic response of a surface-piercing hydrofoil in multi-phase flows. Part 1. Passive hydroelasticity

Compliant lift-generating surfaces have widespread applications as marine propellers, hydrofoils and control surfaces, and the fluid–structure interactions (FSI) of such systems have important effects upon their performance and stability. Multi-phase flows like cavitation and ventilation alter the hydrodynamic and hydroelastic behaviours of lifting surfaces in ways that are not yet completely understood. This paper describes experiments on one rigid and two flexible variants of a vertical surface-piercing hydrofoil in wetted, ventilating and cavitating conditions. Tests were conducted in a towing tank and a free-surface cavitation channel. This work, which is Part 1 of a two-part series, examines the passive, or flow-induced, fluid–structure interactions of the hydrofoils. Four characteristic flow regimes are described: fully wetted, partially ventilated, partially cavitating and fully ventilated. Hydroelastic coupling is shown to increase the hydrodynamic lift and yawing moments across all four flow regimes by augmenting the effective angle of attack. The effective angle of attack, which was derived using a beam model to account for the effect of spanwise twisting deflections, effectively collapses the hydrodynamic load coefficients for the three hydrofoils. A generalized cavitation parameter, using the effective angle of attack, is used to collapse the lift and moment coefficients for all trials at a single immersed aspect ratio, smoothly bridging the four distinct flow regimes. None of the hydrofoils approached the static divergence condition, which occurs when the hydrodynamic stiffness negates the structural stiffness, but theory and experiments both show that ventilation increases the divergence speed by reducing the hydrodynamic twisting moment about the elastic axis. Coherent vortex shedding from the blunt trailing edge of the hydrofoil causes vortex-induced vibration at an approximately constant Strouhal number of 0.275 (based on the trailing edge thickness), and leads to amplified response at lock-in, when the vortex-shedding frequency approaches one of the resonant modal frequencies of the coupled fluid–structure system.

Effect of novel short-length wavy-tape turbulators on fluid flow and heat transfer: experimental study

ABSTRACTThe heat transfer characteristics of turbulent flow regime through a circular tube with short- and full-length wavy-tape inserts were experimentally investigated. Air was used for Reynolds numbers between 6,000 and 20,000 with different combinations of wave, tape thickness, and diameter ratios. It was found that wavy-tape inserts enhanced the heat transfer by up to 67% higher than smooth tubes. For approximately the same pumping power, the heat transfer for full-length wavy tape was approximately 25% higher than for short-length wavy tape. However, the pumping power of full-length tape was 26% higher than for short-length tape.

A preconditioned solver for sharp resolution of multiphase flows at all Mach numbers

A preconditioned five-equation two-phase model coupled with an interface sharpening technique is introduced for simulation of a wide range of multiphase flows with both high and low Mach regimes. Harten-Lax-van Leer-Contact (HLLC) Riemann solver is implemented for solving the discretized equations while tangent of hyperbola for interface capturing (THINC) interface sharpening method is applied to reduce the excessive diffusion of the method at the interface. In this work, preconditioning technique is used in a system of equations including viscous and capillary effects. Several one- and two-dimensional test cases are used to evaluate the performance and accuracy of this method. Numerical results demonstrate the efficiency of preconditioning in low Mach number flows. Comparisons between results of preconditioned and conventional system highlight the necessity of using preconditioning technique to reproduce main characteristics of low-speed flow regimes. Additionally, preconditioned systems transform to the conventional systems at high Mach number flows thus exhibiting the same level of accuracy as the standard flow solver. Therefore, the preconditioned compressible two-phase method can be used as an all-speed two-phase flow solver accounting for capillary and viscous stresses.

Flow pattern of double-cavity flow at high Reynolds number

The flow structure in a turbulent double-cavity flow has been studied experimentally and numerically. The dynamics of the two-component instantaneous velocity vector fields measured by an optical smoke image velocimetry method and calculated using the ANSYS Fluent 19.2 software has been derived. For a wide range of dynamic similarity numbers of shape factor and ReL, the flow resistance coefficients for the cavity and relative flow mass transfer with the cavities have been estimated; three characteristic flow regimes of double-cavity flow have been distinguished and described; the flow pattern map via the ReL number and shape factor has been obtained.

Experimental study on flow regimes in debris bed formation behavior with mixed-size particles

During a core disruptive accident of sodium-cooled fast reactors, the fragmented debris released from the reactor core will start to sediment and form debris beds within the lower plenum region of the reactor vessel. To ascertain the characteristics of flow regimes during this debris bed formation process, in our earlier publications based on a great number of experiments conducted using mono-sized spherical and non-spherical solid particles, four typical flow regimes (i.e. the particle-suspension regime, the pool-convection dominant regime, the transitional regime and the particle-inertia dominant regime) were identified. In addition, a flow-regime model, including the base model for predictions of spherical particles and the extension scheme for non-spherical particles, has been successfully developed. In this study, motivated to further understand this behavior at a condition of more realistic particle mixture, a new series of simulated experiments using mixed-size particles is conducted under the gravity-driven release from a nozzle into a static two-dimensional water pool. Through detailed analyses, it is found that the base model, by employing the area mean diameter, can predict the overall regime transition under the condition of mixed-size particles reasonably well. Even if a quantity of effective sphericity is introduced, the previous extension scheme for non-spherical particles lacks the capability to provide satisfactory predictions. To improve the prediction using the form of extension scheme, a new correction scheme based on the volume-mean diameter and the degree of convergence in particle-size distribution is suggested and validated. The conducted analyses in this study also indicate that due to the difference in component inertia, the potential separation and stratification of solid particles are likely to exist during an actual debris bed sedimentation process in a core disruptive accident.

Power-Law Fluid Flow in a T-Shaped Channel Under the Action of Assigned Pressure Drop

Plane non-Newtonian incompressible fluid flow in a T-shaped channel is considered. The effective viscosity is determined according to the Ostwald–de Waele law. The fluid moves under the action of the given pressure drop in the boundary sections of the channel. The no-slip condition is fulfilled on the solid walls. The problem is solved numerically by the control volume method with the use of the SIMPLE procedure. As a result of the investigation carried out, the characteristic flow regimes have been revealed. The influence of the basic parameters of the problem on the flow pattern has been demonstrated, and the dimensionless relations of flow characteristics have been constructed.

Scaling the impacts of pore-scale characteristics on unstable supercritical CO2-water drainage using a complete capillary number

Geological carbon storage in deep aquifers involves displacement of resident brine by supercritical CO2 (scCO2), which is an unstable drainage process caused by the invasion of less viscous scCO2. The unstable drainage is greatly complicated by aquifer heterogeneity and anisotropy and regarded as one of the key factors accounting for the uncertainty in storage capacity estimates. The impacts of pore-scale characteristics on the unstable drainage remain poorly understood. In this study, scCO2 drainage experiments were conducted at 40 °C and 9 MPa using a homogeneous elliptical micromodel with low or high anisotropy, a homogeneous/isotropic hexagonal micromodel, and a heterogeneous sandstone-analog micromodel. Each initially water-saturated micromodel was invaded by scCO2 at different rates with logCa (the capillary number) ranging from −7.6 to −4.4, and scCO2/water images were obtained. The measured CO2 saturations in these centimeter-scale micromodels vary considerably from 0.08 to 0.93 depending on the pore-scale characteristics and capillary number. It was also observed that scCO2 drainage follows the classic flow-regime transition from capillary fingering through crossover to viscous fingering for either of the low-anisotropy elliptical and heterogeneous micromodels, but with disparate crossover zones. The crossover zones of scCO2 saturation were then unified with the minimum scCO2 saturation occurring at logCa*=-4.0 using the complete capillary number(Ca*) that considers pore characteristics. For the hexagonal and the high-anisotropy elliptical micromodels, a monotonic increase in scCO2 saturation with increasing Ca* (without crossover) was observed. It appears that the complete capillary number is more appropriate than the classic capillary number when characterizing flow regimes and CO2 saturation in different pore networks.

Rate Decline Behavior of Selectively Completed Horizontal Wells in Naturally Fractured Oil Reservoirs

Selectively completed horizontal wells (SCHWs) can significantly reduce cost of completing wells and delay water breakthrough and prevent wellbore collapse in weak formations. Thus, SCHWs have been widely used in petroleum development industry. SCHWs can shorten the effective length of horizontal wells and thus have a vital effect on production. It is significant for SCHWs to study their rate decline and flux distribution in naturally fractured reservoirs. In this paper, by employing motion equation, state equation, and mass conservation equation, three-dimension seepage differential equation is established and corresponding analytical solution is obtained by Laplace transform and finite cosine Fourier transform. According to the relationship of constant production and wellbore pressure in Laplace domain, dimensionless rate solution is gotten under constant wellbore pressure in Laplace domain. Dimensionless pressure and pressure derivate curves and rate decline curves are drawn in log-log plot and seven flow regimes are identified by Stehfest numerical inversion. We compared the simplified results of this paper with the results calculated by Saphir for horizontal wells in naturally fractured reservoirs. The results showed excellent agreement. Some parameters, such as outer boundary radius, storativity ratio, cross-flow coefficient, number and length of open segments, can obviously affect the rate integral and rate integral derivative log-log curves of the SCHWs. The proposed model in this paper can help better understand the flow regime characteristics of the SCHWs and provide more accurate rate decline analysis of the SCHWs data to evaluate formation.

Integrating Model Uncertainty in Probabilistic Decline-Curve Analysis for Unconventional-Oil-Production Forecasting

SummaryDecline-curve analysis (DCA) for unconventional plays requires a model that can capture the characteristics of different flow regimes. Thus, various models have been proposed. Traditionally, in probabilistic DCA, an analyst chooses a single model that is believed to best fit the data. However, several models might fit the data almost equally well, and the one that best fits the data might not best represent the flow characteristics. Therefore, uncertainty remains regarding which is the “best” model. This work aims to integrate model uncertainty in probabilistic DCA for unconventional plays.Instead of identifying a single “best” model, we propose to regard any model as potentially good, with goodness characterized by a probability. The probability of a model being good is interpreted as a measure of the relative truthfulness of this model compared with the other models. This probability is subsequently used to weight the model forecast. Bayes' law is used to assess the model probabilities for given data. Multiple samples of the model-parameter values are obtained using maximum likelihood estimation (MLE) with Monte Carlo simulation. Thus, the unique probabilistic forecasts of each individual model are aggregated into a single probabilistic forecast, which incorporates model uncertainty along with the intrinsic uncertainty (i.e., the measurement errors) in the given data.We demonstrate and conclude that using the proposed approach can mitigate over/underestimates resulting from using a single decline-curve model for forecasting. The proposed approach performs well in propagating model uncertainty to uncertainty in production forecasting; that is, we determine a forecast that represents uncertainty given multiple possible models conditioned to the data. The field data show that no one model is the most probable to be good for all wells.The novelties of this work are that probability is used to describe the goodness of a model; a Bayesian approach is used to integrate the model uncertainty in probabilistic DCA; the approach is applied to actual field data to identify the most-probable model given the data; and we demonstrate the value of using this approach to consider multiple models in probabilistic DCA for unconventional plays.

Future evolution and uncertainty of river flow regime change in a deglaciating river basin

Abstract. The flow regimes of glacier-fed rivers are sensitive to climate change due to strong climate–cryosphere–hydrosphere interactions. Previous modelling studies have projected changes in annual and seasonal flow magnitude but neglect other changes in river flow regime that also have socio-economic and environmental impacts. This study employs a signature-based analysis of climate change impacts on the river flow regime for the deglaciating Virkisá river basin in southern Iceland. Twenty-five metrics (signatures) are derived from 21st century projections of river flow time series to evaluate changes in different characteristics (magnitude, timing and variability) of river flow regime over sub-daily to decadal timescales. The projections are produced by a model chain that links numerical models of climate and glacio-hydrology. Five components of the model chain are perturbed to represent their uncertainty including the emission scenario, numerical climate model, downscaling procedure, snow/ice melt model and runoff-routing model. The results show that the magnitude, timing and variability of glacier-fed river flows over a range of timescales will change in response to climate change. For most signatures there is high confidence in the direction of change, but the magnitude is uncertain. A decomposition of the projection uncertainties using analysis of variance (ANOVA) shows that all five perturbed model chain components contribute to projection uncertainty, but their relative contributions vary across the signatures of river flow. For example, the numerical climate model is the dominant source of uncertainty for projections of high-magnitude, quick-release flows, while the runoff-routing model is most important for signatures related to low-magnitude, slow-release flows. The emission scenario dominates mean monthly flow projection uncertainty, but during the transition from the cold to melt season (April and May) the snow/ice melt model contributes up to 23 % of projection uncertainty. Signature-based decompositions of projection uncertainty can be used to better design impact studies to provide more robust projections.

Bubble mapping: three-dimensional visualisation of gas–liquid flow regimes using electrical tomography

It is well known that electrical tomography is capable of ‘seeing’ through opaque pipe walls and flow media. However, due to the relatively low spatial resolution, electrical tomograms are ineffective on visualisation of small bubbles or sharp interfaces between large bubbles and the liquid. These limitations give rise to ambiguity in human and/or machine perception of flow dynamics from presenting bubble cluster and blurry boundaries of large bubbles in faint colour or grey. In this paper, a binary approach, called bubble mapping, is proposed to enhance the visibility of flow regime in gas–liquid pipeline flows. With the input gas concentration tomograms reconstructed by an electrical tomography, the method takes the major visual characteristics of typical flow regimes in common recognition as a prior knowledge and replaces the conventional colour mapping with a number of bubbles and their mergence with a thresholding value. With this approach, a stack of cross-sectional tomograms by electrical tomography is transformed and displayed as a collection of individual gas bubbles. The transformation is done with the help of a lookup table indexed by bubble size and an enhanced isosurface algorithm for vivid three-dimensional visualisation. This new approach has been applied to a gas-in-water flow rig and its performance is compared with photo images taken by a high-speed camera. Reasonable agreements have been obtained for common flow regimes including bubbly flow, stratified flow, plug flow, slug flow and annular flow in horizontal pipe and bubbly flow, slug flow and annular flow in vertical pipe. Results evidence the method can provide a photorealistic flow visualisation and therefore enhance the visibility of electrical tomograms for visual identification of flow regime, particularly for opaque media in industrial flows.

Water Yield Responses to Gradual Changes in Forest Structure and Species Composition in a Subboreal Watershed in Northeastern China

Relationships between forest cover and streamflow have been studied worldwide, but only a few studies have examined how gradual changes in forest structure and species composition due to logging and climate change affect watershed water yield (Q) and flow regimes. In this study, we analyzed long-term (45 years) hydrologic, climate and forest dynamics data from the subboreal Tahe watershed in northeastern China. Our purpose was to evaluate the effects of forest logging and regeneration on changes in forest biomass and species and to quantify the subsequent impact on mean annual streamflow and flow regime under a changing climate. The study watershed was dominated by old-growth larch (Larix gmelinii Rupr.) during the 1970s, but gradually transformed into young deciduous larch mixed with deciduous broad-leaved birch (Betula platyphylla Sukaczev) during the 2010s. During the same period, the watershed experienced climate change with a significant increase in air temperature of 0.028 ℃/year. We applied eight sensitivity-based techniques to separate the effects of climate change on water yield from those due to forest changes. We used flow duration curves (FDCs) to characterize flow regimes by dividing the study into four key periods based on the proportional change of larch and birch trees. We found that the mean annual streamflow decreased by 10 mm (−16 mm attributed to forest change and +6 mm to climate change) between the 1984–1994 period and the 2006–2016 period when the proportion of birch increased by 20% with a similar total forest volume in the later period. The mean annual streamflow increased from 216 mm to 270 mm (+35.5 mm due to forest change vs +17.7 mm due to climate change) when forest volume decreased by 18.7% (17 m3/ha) between the 1970s and 1984–1994. Water yield changed only slightly (3.5 mm) when forest volume increased by 8.7% (6 m3/ha) from 2000 to 2011. In addition, the magnitude of high flow and low flow increased following deforestation and a shift in species composition from a period (1984–1994) with 70% larch with 30% birch to a later period (2006–2016) with 50% larch with 50% birch. Both high flow and low flow decreased coinciding with a reforestation period (2006–2016). Our results highlight complex interactions among climate, forest structure, total biomass, and plant diversity (trees species composition) in influencing watershed hydrology. Further study is needed to examine the effects of ecohydrological processes such as evapotranspiration in larch and birch forests on hydrologic changes across multiple scales.