Runoff Characteristics Research Articles

Investigation of the EWT–PSO–SVM Model for Runoff Forecasting in the Karst Area

As the runoff series exhibit nonlinear and nonstationary characteristics, capturing the embedded periodicity and regularity in the runoff series using a single model is challenging. To account for these runoff characteristics and enhance the forecasting precision, this research proposed a new empirical wavelet transform–particle swarm optimization–support vector machine (EWT–PSO–SVM) hybrid model based on “decomposition-forecasting-reconstruction” for runoff forecasting and investigated its effectiveness in the karst area. First, empirical wavelet transform (EWT) was employed to decompose the original runoff series into multiple subseries. Second, the support vector machine (SVM) optimized by particle swarm optimization (PSO) was applied to forecast every signal subseries. Finally, this study summarized the predictions of the subseries to reconstruct the ultimate runoff forecasting. The developed forecasting model was assessed by applying the monthly runoff series of the Chengbi River Karst Basin, and the composite rating index combined with five metrics was adopted as the performance evaluation tool. From the results of this research, it is clear that the EWT–PSO–SVM model outperforms both the PSO–SVM model and the SVM model in terms of the composite rating index, reaching 0.68. Furthermore, verifying the performance stability, the developed model was also compared with PSO–SVM and SVM models under different input data structures. The comparison demonstrated that the hybrid EWT–PSO–SVM model had a robust performance superiority and was an effective model that can be applied to karst area runoff forecasting.

Adaptation of SWAT Watershed Model for Stormwater Management in Urban Catchments: Case Study in Austin, Texas

Computer simulation models are a useful tool in planning, enabling reliable yet affordable what-if scenario analysis. Many simulation models have been proposed and used for urban planning and management. Still, there are a few modeling options available for the purpose of evaluating the effects of various stormwater control measures (SCM), including LID (low-impact development) controls (green roof, rain garden, porous pavement, rainwater harvesting), upland off-line controls (sedimentation, filtration, retention–irrigation) and online controls (detention, wet pond). We explored the utility and potential of the Soil and Water Assessment Tool (SWAT) as a modeling tool for urban stormwater planning and management. This study demonstrates how the hydrologic modeling strategies of SWAT and recent enhancements could help to develop efficient measures for solving urban stormwater issues. The case studies presented in this paper focus on urban watersheds in the City of Austin (COA), TX, where rapid urbanization and population growth have put pressure on the urban stormwater system. Using the enhanced SWAT, COA developed a framework to assess the impacts on erosion, flooding, and aquatic life due to changes in runoff characteristics associated with land use changes. Five catchments in Austin were modeled to test the validity of the SWAT enhancements and the analytical framework. These case studies demonstrate the efficacy of using SWAT and the COA framework to evaluate the impacts of changes in hydrology and the effects of different regulatory schemes.

Impact assessment of land use/land cover changes on surface runoff characteristics in the Shetrunji River Basin using the SWAT model

Abstract Land use/land cover (LU/LC) change has a considerable effect on the runoff characteristics of any watershed. LU/LC change studies are necessary for policymakers to identify the challenges and adopt the course of action such as soil and water conservation measures for improvement. The current research is undertaken for the upper Shetrunji River basin using a hydrological model linked with GIS. Input data like LU/LC, meteorological, and soil elements are necessary to execute watershed modeling. The model was calibrated and validated in SWAT-CUP using the SUFI-2 algorithm. The data from 2000 to 2010 were utilized for calibration, whereas the data from 2011 to 2020 were used for validation with a three-year warm-up period from 1997 to 1999. LU/LC change detection has been accomplished using ERDAS IMAGINE 2015 via a supervised classification approach. Close agreement was obtained between simulated and observed streamflow data during model calibration (NSE = 0.74 and R2 = 0.78) and validation (NSE = 0.70 and R2 = 0.73). LU/LC change detection shows that agricultural, urban, and water body areas increased between 2000–2010 and 2010–2020, and forest areas increased in 2010 and decreased in 2020. Thus, it is concluded that the change in LU/LC significantly influenced the runoff of the upper Shetrunji River basin.

Developing a Methodology for Model Intercomparison and Its Application to Improve Simulated Streamflow by Land Surface Models

Abstract Runoff generated by land surface models (LSMs) is extensively used to predict future river discharge under global warming. However, the structural bias of LSMs, the precipitation bias of the climate model, and other factors could cause the runoff to be biased. A model intercomparison study can help understand LSM behavior. Traditional model intercomparison can discover output variation and evaluate performance, but explaining the reason for the difference is challenging. This study developed a novel method to identify the reasons for disparities and suggest improvements. Consequently, we investigated the impacts of model settings by adopting the settings of another model in one model until it can mimic similar features in its output. Hence, we developed a process called the “emulation model.” We employed two LSMs [Simple Biosphere with Urban Canopy (SiBUC) and Meteorological Research Institute Simple Biosphere model (MRI-SiB)] in the Thai River basin. SiBUC produced a higher surface runoff than MRI-SiB, and the development of the MRI-SiB emulation revealed the cause of this variation. The differences in runoff characteristics affected streamflow estimation. For instance, the SiBUC peak discharge was faster and higher than observed in the dry year. Conversely, there was a tendency to underestimate the flow estimated by MRI-SiB runoff during the transition from dry to wet seasons. Incorporating other model settings can alleviate the shortcomings of each model. Overall, the proposed method can identify the strengths and weaknesses of a model and enhance the reproducibility of the hydrological characteristics of the observed discharge in the basin. Significance Statement This study aims to develop a new methodology for model intercomparison to identify the reasons for model output variation. Understanding why models behave differently is important to enhancing the reliability of model prediction. Our findings guide what affects disparities in land surface model runoff-based streamflow estimation, which will help reduce the uncertainty of future flood and drought predictions.

Quantifying the efficacy of Low Impact Developments (LIDs) for flood reduction in micro-urban watersheds incorporating climate change

Urban floods have become more frequent and devastating in recent decades. Low impact developments (LIDs) have gained wide acceptance as a more sustainable and effective technique for mitigating urban flooding. This study examines the hydrological control effects of LIDs on mitigating runoff depth and peak runoff in the context of climate change for four micro-watersheds (A, B, C and D) in northeast India. In addition, attempts have been made to determine whether redesigning the existing drainage helps reduce runoff in the study area. Results show that redesigning the drainage system has resulted only in 2.5–3.6% reduction in runoff depth for the four micro-watersheds. LIDs were effective in managing the stormwater in all four micro-watersheds. Among the four LIDs considered (green roof, permeable pavements, infiltration trenches, and rain barrels), the green roof showed the highest percentage reduction in runoff characteristics. Climate change analysis has shown a significant increase in the runoff characteristics in all four watersheds. For watersheds A, B, C, and D, the green roof effectively reduced runoff by 30%–38%, 83%, 50%, and 34%, respectively. This study will help the decision-makers to assess and choose the best LIDs to minimize the risk of flooding.

Proposed Countermeasures against Woody Debris Damage Considering Runoff Characteristics

In recent years, a combination of forestry decline and global climate change has led to heavy rains and landslides in Japan that have caused extensive forest damage through woody debris outflow. The current configuration of impermeable sabo dams has insufficient capacity to capture woody debris under these conditions; therefore, improvements to permeable sabo dams, which have a high woody debris capture capacity, are underway; these sometimes involve the addition of steel fittings. In this study, we examined the effectiveness of such measures in consideration of the factors affecting woody debris flow. After reviewing a woody debris outflow that occurred during a heavy rain disaster in northern Kyushu, Japan, we propose woody debris countermeasures that consider basin and runoff characteristics. Our results indicate that woody debris flow occurs later than sediment flow. Therefore, we performed experiments to test the effectiveness of various methods to slow water flow using the terrain conditions at the nearest valley outflow point. Finally, we propose woody debris countermeasure policies considering basin characteristics, to promote the future preservation of river basins.

Evaluation of the geomorphological scenario of Shimsha River Basin, Karnataka, India.

Drainage morphometric analysis is very substantial in determining the characteristics of a river basin. It is performed through spatial analysis, which helps study the various hydrological interactions and responses in the watershed. In this research, the authors have tried to study the geomorphological scenario of the Shimsha River basin using the remote sensed data, toposheets, and geographic information systems tools. In the current study, linear, aerial, and relief parameters are derived and analysed to evaluate the runoff and erosion characteristics of the basin. The stream pattern of the Shimsha River is mostly dendritic with a sixth-order stream and a drainage density of 0.56 km/km2. According to the morphometric characteristics, the study area appears to be in the equilibrium stage of development, slightly elongated, with moderate to low flow rates and reduced sensitivity to erosion. The hypsometric curve and hypsometric integral value of the Shimsha River basin show the mature phase of the geomorphic evolution of the basin and imply that runoff will be moderate to high. The asymmetry factor of the Shimsha River basin is 49.3, which specifies that the basin is slightly tilted towards the right. The study's results clarify the phenomena of runoff and erosion, which is crucial for watershed management initiatives.

Dynamic evolution of attribution analysis of runoff based on the complementary Budyko equation in the source area of Lancang river

Analyzing runoff variation characteristics and quantifying the impact of different factors on the runoff variation in the source area of Lancang River, are of significance for scientific response to the ecological protection of the region and Lancang River. The Budyko method is adopted to quantitatively calculate the contribution rate of human factors and climate factors to runoff change in the source area of Lancang River. The results show that: 1) the annual runoff at Qamdo hydrological station decreased significantly during 1961–2018. 2) 1966 is the mutation year of runoff at Qamdo hydrological station from 1961 to 2018. 3) At the Qamdo hydrological station, the contribution rates of precipitation P) to the runoff change are 16.92–72.8% before 1990 and -1.91∼-53.61% after 1990, the contribution rates of potential evaporation (ET0) to the runoff changes are 0.14–39.19%. The contribution rates of human factors ω) to the runoff changes are between 26.9% and 114.42%. This study has important theoretical reference and practical significant for maintaining the integrity and sustainable development of the ecosystems of the Lancang River.

Runoff Characteristics based on Geo-morphological Instantaneous Unit Hydrograph over Humid Region of Himalayas of Bhutan

It is critical to quantify runoff that would be generated due to rainfall in a catchment which would in turn help in predicting the nature of response from a catchment that can be used to come up with a strategic planning and implementation to prevent from certain foreseen or unforeseen calamities. Most of the sub-catchments in Bhutan are un-gauged, which results in the insufficient hydrological data for validating the accuracy of any hydrological model. The current study is approached with identification of reliable hydrological model with the help of real data obtained through customized gauging stations developed using Arduino chip that works on batteries, using sonar sensors. To overcome the issue of insufficient data sets, Om chu river, situated at Phuentsholing is chosen to be gauged for the study. This practical approach towards the analysis of intensity and response of catchment, would help engineers to foresee the possible calamities if any and design the structures accordingly with the reasonable costing. Key Words: quantify, runoff, catchment response, ungauged, hydrological models, arduino

How does the explicit treatment of convection alter the precipitation–soil hydrology interaction in the mid-Holocene African humid period?

Abstract. Global climate models with coarse horizontal resolution are largely unable to reproduce the monsoonal precipitation pattern over North Africa during the mid-Holocene. Here we present the first regional, storm-resolving simulations with an idealized but reasonable mid-Holocene vegetation cover. In these simulations, the West African monsoon expands farther north by about 4–5∘, and the precipitation gradient between the Guinea coast and the Sahara decreases compared to simulations with a barren Sahara as it is today. The northward shift of monsoonal precipitation is caused by land surface–atmosphere interaction, i.e., the coupling of soil moisture and precipitation, as well as interactions of the land surface with the large-scale monsoon circulation (e.g., the African easterly jet). The response of the monsoon circulation to an increased vegetation cover is qualitatively similar but more pronounced in parameterized convection simulations. We attribute the differences in monsoonal precipitation to differences in soil moisture that are strongly controlled by runoff and precipitation characteristics. If precipitation is intense and falls over a spatially small region, as in our storm-resolving simulations, about 35 % of all precipitation water goes into runoff instead of filling soil moisture storage. In contrast, in light and spatially more homogeneous precipitation, as produced in our parameterized convection simulations, only some 20 % leaves the grid cell as runoff. Therefore, much more water is available to maintain high soil moisture content. We confirm the significant role of soil moisture and runoff by performing simulations with the same constant soil moisture field in both storm-resolving and parameterized convection simulations. These constant soil moisture simulations cancel the effect of lower soil moisture on the land–atmosphere feedback cycle in our storm-resolving simulations. We show that precipitation strongly increases in the storm-resolving simulations, especially in moisture-controlled regions, such as the northern Sahel and Sahara, and reaches equally high values as in parameterized convection simulations. Our study highlights how the type of rainfall (e.g., local and intense or widespread and light) impacts soil moisture and thus land–atmosphere feedbacks. This is contrary to many studies that focus mainly on the amount of rainfall and how it modifies land–atmosphere feedbacks. Moreover, this study suggests that comprehensive land-surface schemes, which appropriately respond to varying precipitation characteristics, are needed for studying land surface–atmosphere interaction.

Impacts of retention basins on downstream flood peak attenuation in the Odaw river basin, Ghana

Study regionOdaw River Basin (ORB) in Ghana Study focusWe simulated and examined the impacts of retention basin as a hydraulic structure in attenuating the flood peaks downstream of the ORB with a coupled HEC-HMS and HEC-RAS models for different flood scenarios. Calibrated and validated HEC-HMS models were used to forecast floods in terms of peak flows and results forced into the 2D Unsteady flow HEC-RAS model to simulate flood inundation areas.New hydrological insight for the region: The calibrated and validated HEC-HMS model indicated good performance (NSE > 0.65) in simulating the runoff characteristics of the basin. Forecasted peak flows with the calibrated model for return periods of 30-to-1-year were 131.1 m3/s, 121.6 m3/s, 106.4 m3/s, 88.8 m3/s and 59.3 m3/s respectively for the “without” a retention basin scenario within the ORB. In the “with” retention basin scenario, attenuated peak flows were observed downstream the ORB by 8.1 % (120.5 m3/s), 8.4 % (111.4 m3/s), 9.1 % (96.7 m3/s), 13.6 % (76.7 m3/s) and 13.2 % (51.5 m3/s) respectively for the different return periods. Flood volumes reaching downstream of the basin reduced by 2.3 %, 2.5 %, 2.7 %, 3.0% and 3.8 % respectively due to the presence of the retention basin. The retention basin increased the basin lag time by an average of 4 h across all different flood scenarios. The introduction of retention basins will serve a pivotal role in flood management and planning in the ORB.

Runoff characteristics of headwater catchments in a young volcanic region

Because volcanic rocks have high permeability, rainfall quickly infiltrates into the ground. Perennial rivers often do not exist in volcanic areas. However, available studies elucidating hydrologic characteristics and the mechanisms of stream formation in young volcanic areas are limited in number, extent, and coverage prohibiting a comprehensive understanding of runoff formation. By measuring river discharge for two years, we examined the characteristics of surface runoff in four adjacent headwater catchments within a young volcanic area of Mt.Fuji. The runoff coefficient R is small, rainfall thresholds for discharge are large, and the lag time Tlag and duration D of rainfall-runoff events are short. These characteristics can be explained by the groundwater flow as the dominant runoff mechanism with high hydraulic conductivity. Due to differences in topography and the depth of groundwater, some differences existed amongst the four adjacent catchments. In addition, a comparison of runoff characteristics between the young volcanic headwater catchments (VHCs) and non-volcanic headwater catchments (NVHCs) reported in other studies established that young VHCs have a smaller R, a shorter Tlag and D, and a larger runoff threshold for storm runoff than NVHCs. These differences are attributed to differences in the hydraulic conductivity of the underlying geology. These findings should help improve hydrological models and river structures for flood prevention.

Análisis de la evolución de las características de la escorrentía y de las precipitaciones en la cuenca este del río Pi, China

The natural hydrologic cycle is greatly influenced by climate change. In particular, substantial spatiotemporal variations in precipitation can occur in some mountainous areas, and thus it is very important to identify hydrological processes in watershed with high resolution. To analyze the problem above, the Mann-Kendall test, the moving T-test, Sen’s slope estimator and Spearman rank correlation test combined with the spatial interpolation function of ArcGIS, are used to analyze and discuss the evolution of the spatiotemporal distribution characteristics of precipitation and Runoff in a typical small watershed of mountainous areas. The result is precipitation showed a downward trend from south to north and from high-altitude to low-altitude regions. And the difference mainly occurred in the western part of the basin. And the conclusions show the following: 1) An abrupt change in both precipitation and Runoff sequences occurred in 1991; 2) the extreme value of the precipitation trend shifted from the central region to the western region; 3) for the ratio of Runoff in the flood season to annual Runoff, the sequence showed a significant upward trend (95 % confidence level), indicating that the uneven distribution of Runoff has significantly increased since the 1960s.

Impacts of elevational variability of climate and frozen ground on streamflow in a glacierized catchment in Tibetan Plateau

In cold and high-elevation mountainous catchments, climate and landscape vary with elevation, which leads to elevational variability in runoff. The short-term variation and long-term change of climate would temporally and permanently alter the conditions of frozen ground and runoff characteristics at different elevation zones. In this study, a conceptually hydrological model is developed to investigate the responses of soil freeze–thaw and runoff processes to climate change from 1979 to 2013 in a glacierized catchment in the Tibetan Plateau (TP). Results show that our model can accurately reproduce the observed daily streamflow. In addition to rainfall (63.8%), meltwater from glacier (22.2%) and snowpack (14.0%) are also key contributors to streamflow, especially at high elevations. As temperature declines with rising of elevation, the elevation-runoff relationship depicts a convex formation with a runoff peak at the elevation of ∼5800 m. Below 5800 m, surface flow increases towards high elevations accompanied by the increase of glacier coverage, while groundwater flow reduces because the enlarged frozen ground areas inhibit the percolation of the infiltrated water. Above 5800 m, the runoff declines sharply as the ground changes to a perennially freezing condition. The long-term climate warming during 1979 ∼ 2013 significantly increases annual runoff with a rate of 12.2 mm/10a. The increment in streamflow is primarily attributed to an increase in surface flow in the summer season when glacier meltwater increases at high elevations. Whereas the permafrost degradation enhances infiltrated water percolation and hence, groundwater flow in the low elevations and the low flow periods. Although climate warming benefits the local water resources availability during the historical periods, streamflow could be substantially decreased if the glacier vanished, which threatens the sustainability of the “water tower” over TP.

The Interaction of Aeolian Sand and Slope on Runoff and Soil Loss on a Loess Slope via Simulated Rainfall under Laboratory Conditions

The wind–water erosion crisscross region, where the topography is complicated, is the most severe area of soil erosion on the Loess Plateau. The wind and terrain both have an impact on the soil water erosion process. In order to evaluate the effects of sand cover on runoff and soil loss characteristics, a series of experiments was conducted in two contrasting treatments. One treatment was a bare loess soil slope serving as the control, and the others were sand-covered loess slopes with five different slopes. The results showed that the runoff time, total runoff yield, and total soil loss were different between the sand-covered slope and the loess slope on the slope of 15°. The sediment concentration of the sand-covered slope was significantly higher than that of the loess slope during the entire rainfall process (p < 0.05). The increase in the slope gradient shortened the surface runoff initiation times and enhanced the total runoff volume and soil loss. The total runoff volume and the total soil loss were 39.7 L and 44.3 kg, respectively, on the sand-covered slope of 10°. When the slope gradient increased from 10° to 30°, the total runoff volume and the total soil loss increased by 22.8 L and 42.8 kg, respectively, while the surface runoff initiation times shortened by 300 s. For the sand-covered slopes, the erosion processes appeared to be mainly dominated by sediment transport. The correlation between soil loss rates and slope gradients demonstrated the secondary polynomial function. In addition, the critical slope of sand-covered slopes was from approximately 23° to 28°. The proportion of sand cover and slope responsible for soil erosion was 3:1, which means the wind effect was more important than the terrace factor in terms of soil water erosion in the wind–water erosion crisscross region. The results provide a theoretical basis for soil erosion control in this area.

Vulnerability of Estuarine Systems in the Contiguous United States to Water Quality Change Under Future Climate and Land‐Use

AbstractChanges in climate and land‐use and land‐cover (LULC) are expected to influence surface water runoff and nutrient characteristics of estuarine watersheds, but the extent to which estuaries are vulnerable to altered nutrient loading under future conditions is poorly understood. The present work aims to address this gap through the development of a new vulnerability assessment framework that accounts for (a) estuarine exposure to projected changes in total nitrogen (TN) and total phosphorus (TP) loads as a function of LULC and climate change under several scenarios, (b) sensitivity, and (c) adaptive capacity. The framework was applied to 112 estuaries and their contributing watersheds across the contiguous U.S., specifically to look at regional variability in estuarine vulnerability to nutrient loading. Study findings revealed that the largest increases in estuarine nutrient loads are expected in the North and South Atlantic regions and eastern Gulf of Mexico, while the lowest increases are expected in the North and South Pacific regions and the western Gulf of Mexico. However, the North Atlantic and the South Pacific had the highest adaptive capacity, which could potentially counteract the effects of LULC and climate change on nutrient loads. Strong variation in predicted estuarine nutrient loads was observed as a function of climate model projections, while projected LULC changes were more consistently associated with elevated loads. Our findings illustrate the benefits of integrating natural and socio‐ecological factors to identify opportunities to develop adaptation plans and policies to mitigate ecological degradation in vitally important estuaries.

Evolutionary Characteristics of Runoff in a Changing Environment: A Case Study of Dawen River, China

Watershed water cycles undergo profound changes under changing environments. Analyses of runoff evolution characteristics are fundamental to our understanding of the evolution of water cycles under changing environments. In this study, linear regression, moving average, Mann–Kendall, Pettitt, accumulative anomaly, STARS, wavelet analysis, and CEEMDAN methods were used to analyze the trends, mutations, and periodic and intrinsic dynamic patterns of runoff evolution using long-term historical data. The intra-annual distribution of runoff in the Dawen River Basin was uneven, with an overall decreasing trend and mutations in 1975–1976. The main periods of runoff were 1.9 and 2.2 years, and the strongest oscillations in the study period occurred in 1978–1983. The runoff decomposition high-frequency term (intra-annual fluctuation term) had a stronger fluctuation frequency, with a period of 0.51–0.55 years, while the low-frequency term (interannual fluctuation term) had a period of 1.55–2.26 years. The trend term for the runoff decomposition tended to decrease throughout the monitoring period and gradually stabilized at the end of the monitoring period, while the period gradually decreased from upstream to downstream. In summary, we used multiple methods to analyze the evolutionary characteristics of runoff, which are of great relevance to the adaptive management of water resources under changing environments.

Optimal operation of inter basin water transfer under the form of water sources interconnection with connected tunnel

Study regionReservoir system on the Han River and Wei River basins, China. Study focusInterbasin water transfer (IBWT) projects are an important means for solving uneven water resource distribution. The water supply efficiency of IBWT is affected by the original project conditions and runoff. Therefore, this study proposes a new form of IBWT, which is called interbasin water transfer with connected tunnel (IBWTWCT), for solving this problem, and the synchronous-asynchronous encounter (SAE) probability of rich-poor runoff is calculated in order to reveal the process of operation and the function of the connected tunnel. New hydrological insights(1) Regarding giving full play to the runoff characteristics and existing engineering regulation performance, IBWTWCT possesses obvious advantages over typical interbasin water transfer (TIBWT), the annual average water transfer increases by 105 million m³ , and it basically fulfills total water demand. (2) The connected tunnel can fully exploit the multi-year regulation performance of the reservoir, reservoir water level drop reaching the maximum of 5.86 % in February during a dry year. (3) The SAE probability of rich-poor runoff significantly impacts the interbasin water transfer project, and the connected tunnel provides a maximum of 209 million m3 water supply for reservoirs in IBWTWCT, while also improving the operational process of the entire system. This research is not limited to improving the comprehensive benefit of the project and could be extended to other interbasin water transfer systems of similar structures.

Effect of land use land cover change on runoff characteristics using curve number: a GIS and remote sensing approach

Effect of land use land cover change on runoff characteristics using curve number: a GIS and remote sensing approach

Assessment of runoff characteristics changes of small and medium-sized rivers in Central Yakutia under the climate change influence

The response of river catchments located on the territory of Russia to climate change in recent decades has been expressed in the emergence of multidirectional trends in the series of annual runoff, maximum water discharges and the value of winter runoff. However, the response of small and medium-sized rivers to the ongoing climate warming has been poorly studied, in contrast to large rivers. In this paper, a comprehensive analysis of the climatic and hydrological characteristics of small and medium-sized rivers of Central Yakutia as well as an assessment of the climate change impact on the river runoff characteristics in various conditions of the region were carried out. It has been established that the revealed positive trends in temperature correspond to the trends typical for the rest of the Russian Federation. The response of the runoff of small and medium-sized rivers to climate change is most significant in the winter-spring months of the year: there is an increase in runoff in the spring and winter periods and for the year as a whole. A feature of the response of the river catchments of the study area in comparison with the European part of Russia and southern Siberia is the presence of statistically significant trends in the series of annual water discharges for most of the studied water gauges. The most noticeable changes (as a percentage of the base period) occurred in the annual runoff of small rivers, because small rivers respond most quickly to external influences. Its expressiveness is determined not only by the degree of changes in climatic characteristics, but also by the features of runoff formation in the watersheds of the study area, in particular, the presence of permafrost.