Basin Simulation Research Articles

Bias Correction of Climate Model’s Precipitation Using the Copula Method and Its Application in River Basin Simulation

During the last few decades, the utilization of the data from climate models in hydrological studies has increased as they can provide data in the regions that lack raw meteorological information. The data from climate models data often present biases compared to the observed data and consequently, several methods have been developed for correcting statistical biases. The present study uses the copula for modeling the dependence between the daily mean and total monthly precipitation using E-OBS data in the Mesta/Nestos river basin in order to use this relationship for the bias correction of the MPI climate model monthly precipitation. Additionally, both the non-corrected and bias corrected data are tested as they are used as the inputs to a spatial distributed hydrological model for simulating the basin runoff. The results showed that the MPI model significantly overestimates the E-OBS data while the differences are reduced sufficiently after the bias correction. The outputs from the hydrological models were proven to coincide with the precipitation analysis results and hence, the simulated discharges in the case of copula corrected data present an increased correlation with the observed flows.

Improving Urban Runoff in Multi-Basin Hydrological Simulation by the HYPE Model Using EEA Urban Atlas: A Case Study in the Sege River Basin, Sweden

In this study, the high-resolution polygonal land cover data of EEA Urban Atlas was applied for land-use characterization in the dynamic multi-basin hydrological model, HYPE. The objective of the study was to compare this dedicated urban land cover data in semi-distributed hydrological modelling with the widely used but less detailed EEA CORINE. The model was set up for a basin including a small town named Svedala in southern Sweden. In order to verify the ability of the HYPE model to reproduce the observed flow rate, the simulated flow rate was evaluated based on river flow time series, statistical indicators and flow duration curves. Flow rate simulated by the model based on Urban Atlas generally agreed better with observations of summer storm events than the CORINE-based model, especially when the daily rainfall amount was 10 mm/day or more, or the flow exceedance probability was 0.02 to 0.5. It suggests that the added value of the Urban Atlas model is higher for heavy-to-medium storm events dominated by direct runoff. To conclude, the effectiveness of the proposed approach, which aims at improving the accuracy of hydrological simulations in urbanized basins, was supported.

Geochemical characteristics of tight sandstone gas and hydrocarbon charging history of Linxing area in Ordos Basin, China

Abstract Genetic type, source, charging history and reasons for secondary biogenic transformation of tight sandstone gas in the Linxing area in China's Ordos Basin have been studied through a combined analysis of gas compositions, isotopes of alkane and carbon dioxide, fluid inclusions and basin simulation. Tight sandstone gas in this area is predominated by methane, and the dryness coefficient is between 0.864 and 0.997 (average = 0.969). The δ13C1 values of methane and ethane in this area range from −44.5‰ to −33.2‰ (average = −39.4‰) and from −27.5‰ to −24.4‰ (average = −25.9‰), respectively. The non-hydrocarbon gases are nitrogen, followed by carbon dioxide and argon, and δ13C of carbon dioxide ranges from −14.6‰ to 8.6‰. The homogenization temperatures of gas and gas-liquid inclusions in P2s and C3t in Linxing range from 80 °C to 170 °C, which are concentrated at 120–130 °C. The identification of gas origin indicates that tight sandstone gas is coal-type gas, which is mainly due to thermal evolution, followed by the mixing of secondary biogenic gas. Geological conditions and gas geochemical characteristics suggest that tight sandstone gas was produced by coal seam and carbonaceous shale in Upper Paleozoic in the Linxing area. The homogenization temperature of inclusion reflects the continuous accumulation process of tight sandstone gas, and the Cretaceous was the main period for gas charging. The monoclinal structure, maturity of source rocks and activity of underground water in this area are the important factors for secondary biogenic gas formation.

Strategies to Improve and Evaluate Physics‐Based Hyperresolution Hydrologic Simulations at Regional Basin Scales

AbstractThe application of physics‐based distributed hydrologic models (DHMs) at hyperresolutions (~100 m) is expected to support several water‐related applications but is still prevented by critical data, model validation, and computational challenges. In this study, we address some of these challenges by applying the TIN‐based Real‐time Integrated Basin Simulator DHM at a nominal resolution of ~88 m in the Río Sonora basin, a regional watershed of ~21,000 km2 in northwest Mexico. First, we generate reliable high‐resolution (1‐km) hydrometeorological forcings by bias correcting reanalysis products with ground observations and applying downscaling routines that use terrain information at high resolution, which is available globally. Second, we develop a strategy to obtain high‐resolution (250‐m) grids of soil parameters by integrating a coarse‐resolution soil map based on the Food and Agriculture Organization classification with recently released high‐resolution global data sets. Third, we apply the model over a decadal period (2004–2013) and use a set of complementary tools, including Taylor diagrams, connectivity analysis, and empirical orthogonal function analysis, to assess its ability to simulate spatial patterns of land surface temperature through comparison with daily remotely sensed products. We find that (i) the hyperresolution‐simulated patterns capture the spatial variability of land surface temperature quite well and (ii) vegetation properties are the major physical factors controlling the discrepancies between simulated and remotely sensed products. The strategies presented here are based on global data sets and robust statistical techniques that can be utilized in different settings with other DHMs, and thus, they provide valuable support for the scientific community focused on hyperresolution hydrologic modeling.

On the lower bound of Budyko curve: The influence of precipitation seasonality

As a boundary condition, the lower bound is a prerequisite for constructing the Budyko framework. However, the traditional lower bound i.e., the horizontal axis is an analytical boundary without considering realistic conditions. In fact, under real-word condition, the lower bound of Budyko curves, representing the maximum value of water yield, should be located above the horizontal axis due to complicated constraints from basin characteristics, especially the precipitation seasonality, a key driver of runoff yield and a dominant factor in constructing Budyko framework. Thus, this study focused on exploring the reasonable location of the lower bound by adequately analyzing potential influence of precipitation seasonality. To do that, multiple hydrological simulations in basins under different climate and topography conditions were developed based on various precipitation scenarios constructed by using Markov chain with full range of precipitation seasonality. To fully understand the influence from precipitation seasonality on the lower bound, the water-energy supply and the basin characteristics were fixed by aridity index and hydrological model parameters, respectively. The results reveal a positive correlation between runoff coefficient and precipitation seasonality with an obvious higher location above the horizontal axis, indicating the horizontal axis is imprecise to describe the upper bound of runoff yield under real-word condition. Furthermore, a potential location of the lower bound above the horizontal axis in Budyko space was found based on runoff yield mechanism under real basin condition, representing a more appropriate boundary condition of Budyko framework.

Evaluation of the GSMaP_Gauge products using rain gauge observations and SWAT model in the Upper Hanjiang River Basin

Global Satellite Mapping of Precipitation (GSMaP) product is an important satellite precipitation product of Global Precipitation Measurement (GPM) mission, which provides an alternative means to ground-based rainfall estimates, in which case a rigorous product assessment was required before implementation. The objective of this paper is to evaluate and calibrate the errors of GSMaP_Gauge (GG) products, then SWAT model is chosen to evaluate its performance in hydrological simulation. It was found that the GG has a superior ability in detecting moderate rainfall events of 10–20 mm/d, while other magnitude accuracy needs to be strengthened. The Nash-Sutcliffe coefficient of efficiency (NS), coefficient of determination (R2) and the percent bias (PBIAS) were used to evaluate hydrological model performance in the daily scale, supporting the view that GG still allow considerable room for improvement. SWAT model driving by GG performed relatively poorly which is 0.77 ≤ R2 ≤ 0.84, 0.53 ≤ NS ≤ 0.64 and |PBIAS| < 9%, while the performance of corrected GG is relatively better that is 0.85 ≤ R2 ≤ 0.87, 0.70 ≤ NS ≤ 0.75 and |PBIAS| < 15%. Through the error's correction of GG, it brings a better performance of runoff simulation under SWAT modeling, leading to 11.94% and 6.1% maximum increase in NS and R2 respectively. Certain shortcomings are also noted that improvements to the relative runoff depth errors are limited or worse. But in general, GSMaP product has the potential to be an alternative data source for the research on hydrological simulation and water resources management in data-poor or ungauged basins.

Geochemical features and genetic mechanism of deep-water source rocks in the Senegal basin, West Africa

This paper discusses the maturity of source rocks of the Senegal basin through basin simulation, so as to get a better understanding of oil-source correlation. Based on the analysis of pyrolysis chromatography and total organic carbon (TOC) data of core samples taken from 11 wells, the model of Cenomanian-Turonian marine sediment-organic facies was established, and the genetic mechanism of high-quality source rocks was clarified. The results show that source rocks in the Senegal Basin may occur in the Aptian-Albian of Lower Cretaceous and Cenomanian-Turonian of Upper Cretaceous. One is hybrid organic facies in the shallow carbonate platforms in the shelf area and is characterized by moderate to high TOC (&lt;3%) and hidrogen index ? HI, (100-400 mg HC/g). The other is well-preserved marine facies in continental slope to abyssal sea, with high TOC (&gt;3%) and high HI (max 900 mg HC/g TOC). Molecular fossils originating from aryl carotene are the indicator of the existence of euphotic zone in the ancient ocean. The compounds of aryl isoprenes and sulfurous aryl isoprenes are detected in the black shale samples of well DSDP 367. They rooted in photosynthetic green sulfur bacteria and the carbon isotope value of these compounds is higher 10?~15? than those of fossil molecules of algae and cyanobacteria. Two packages of oil-prone source rocks separately occurr in the Aptian-Albian of Lower Cretaceous and Cenomanian-Turonian of Upper Cretaceous. High-graded marine source rocks of the Senegal Basin may occur in a sulfurous, anoxic deep-water environment with sufficient carbon sequestration.

The magma thermal field and the shallow-level gas accumulation of tight gas reservoirs in the middle-eastern parts of the Qinshui Basin

In this study, the metal-non-metal mineral gas-water hydrothermal concept is used to analyze the movement channels of magmatic heating water. Further, the concept of fractures-faults-cracks microfissures hierarchical configuration of the movement channels of magmatic heating water is proposed. In addition, the magma thermal field formed by magmatic heating water movement is studied and analyzed. Based on the basin simulation method, which is combined with the paleo-tectonic evolution analysis and restoration of the ancient burial depth in the middle-eastern parts of the Qinshui Basin, the tectonic evolution history, thermal evolution history, and hydrocarbon generation and exhaustion history of tight gas reservoirs in the Yushe-Wuxiang block in the middle-eastern parts of the Qinshui Basin have been investigated. On the basis of the theories and methods that are proposed in this study, the hierarchical configuration of fractures-faults-cracks microfissures movement channels of magmatic heating water in the Yushe-Wuxiang block in the middle-eastern parts of the Qinshui Basin was studied and analyzed. It is observed that the magmatic heating water rises to the source formation through the movement channels of hierarchical configuration, heats the source rocks, accelerates the evolution of the source rock in the shallow layer, and forms a tight gas reservoir.

Evaluation and uncertainty attribution of the simulated streamflow from NoahMP-RAPID over a high-altitude mountainous basin

Accurate hydrological simulations in high-altitude mountainous basins are important for optimizing reservoir operations in hydropower production and flood control. However, the simulations experience substantial uncertainties from the sparse precipitation measurements over complex mountainous topography and the imperfect hydrological process representations over the heterogeneous surface. At the Daduhe river basin, which is a high-altitude mountainous river basin located in the eastern slope of the Tibetan Plateau, daily streamflow over the 2-year period of 2014 and 2015 is simulated using the Noah land surface model with multi-parameterizations (NoahMP) and Routing Application for Parallel computation of Discharge (RAPID) coupled model driven by the Chinese Meteorological Forcing Dataset (CMFD). Two different runoff parameterization schemes of NoahMP are used for the simulations: SIMGM, which is derived from TOPMODEL and parameterizes surface runoff using water table depth, and NOAH, in which surface runoff is parameterized using soil moisture content based on the Philip infiltration model. The simulated streamflow is evaluated at two mainstream gauges on the Daduhe river, Tongjiezi and Longtoushi, in terms of Nash-Sutcliffe Efficiency (NSE), correlation coefficient, bias, and standard deviation. The uncertainty of the simulated streamflow is attributed to different runoff parameterization in NoahMP, the flow wave celerity parameter of RAPID, and the forcing CMFD precipitation data. Results show that the NOAH runoff parameterization scheme outperforms the SIMGM scheme. NOAH satisfactorily reproduced the observed streamflow anomaly and flood timing at the two mainstream gauges, and the correlation coefficients between the simulated and observed streamflow are above 0.85. The NSE for NOAH is approximately 0.3. The mathematical decomposition of NSE reveals that the relatively low NSE value is mainly attributed to the significant streamflow bias. Without the bias, NSE can be improved to approximately 0.7. The bias shows little dependency on the flow wave celerity parameter of RAPID and the runoff parameterization of NoahMP, whereas it closely corresponds to the forcing CMFD precipitation data bias. Comparing the estimated precipitation from Budykos curve and the observed streamflow, CMFD significantly underestimates the basin-averaged precipitation, which leads to the significant streamflow underestimation in the hydrological simulations. CMFD does not correctly represent the orographic effects on precipitation in the Daduhe river basin. Comparing the rain gauge measurements located in low-altitude river valleys, the CMFD precipitation is significant underestimated, suggesting a significantly underestimation in high-altitude precipitation. This study shows that streamflow bias can be reduced by densifying rain gauges at high altitudes. Despite the bias, the NoahMP RAPID coupled model can satisfactorily reproduce streamflow anomalies and flood timing in mountainous basins. As a dam model is already included, the coupled model can be further used to optimize reservoir operations for hydropower production and flood control.

Hydro‐geomorphic behavior of contrasting tropical landscapes and critical zone response to changing climate

AbstractThe potentially important influence of climate change on landscape evolution and on critical zone processes is not sufficiently understood. The relative contribution of hydro‐climatic factors on hillslope erosion rates may significantly vary with topography at the watershed scale. The objective of this study is to quantify the hydro‐geomorphic behavior of two contrasting landscapes in response to different climate change scenarios in the Luquillo Critical Zone Observatory, a site of particular geomorphological interest, in terms of hillslope erosion and rainfall‐triggered landslides. We investigate the extent to which hillslope erosion and landslide occurrence remain relatively invariant with future hydro‐climatic perturbations. The adjacent Mameyes and Icacos watersheds are studied, which are underlain by contrasting lithologies. A high resolution coupled hydro‐geomorphic model based on tRIBS (Triangulated Irregular Network‐based Real‐time Integrated Basin Simulator) is used. Observations of landslide activity and hillslope erosion are used to evaluate the model performance. The process‐based model quantifies feedbacks among different hydrologic processes, landslide occurrence, and topsoil erosion and deposition. Simulations suggest that the propensity for landslide occurrence in the Luquillo Mountains is controlled by tropical storms, subsurface water flow, and by non‐climatic factors, and is expected to remain significant through 2099. The Icacos watershed, which is underlain by quartz diorite, is dominated by relatively large landslides. The relative frequency of smaller landslides is higher at the Mameyes watershed, which is underlain by volcaniclastic rock. While projections of precipitation decrease at the study site may lead to moderate decline in hillslope erosion rates, the simulated erosional potential of the two diverse landscapes likely remains significant. © 2018 John Wiley &amp; Sons, Ltd.

Multimodel assessment of climate change-induced hydrologic impacts for a Mediterranean catchment

Abstract. This work addresses the impact of climate change on the hydrology of a catchment in the Mediterranean, a region that is highly susceptible to variations in rainfall and other components of the water budget. The assessment is based on a comparison of responses obtained from five hydrologic models implemented for the Rio Mannu catchment in southern Sardinia (Italy). The examined models – CATchment HYdrology (CATHY), Soil and Water Assessment Tool (SWAT), TOPographic Kinematic APproximation and Integration (TOPKAPI), TIN-based Real time Integrated Basin Simulator (tRIBS), and WAter balance SImulation Model (WASIM) – are all distributed hydrologic models but differ greatly in their representation of terrain features and physical processes and in their numerical complexity. After calibration and validation, the models were forced with bias-corrected, downscaled outputs of four combinations of global and regional climate models in a reference (1971–2000) and future (2041–2070) period under a single emission scenario. Climate forcing variations and the structure of the hydrologic models influence the different components of the catchment response. Three water availability response variables – discharge, soil water content, and actual evapotranspiration – are analyzed. Simulation results from all five hydrologic models show for the future period decreasing mean annual streamflow and soil water content at 1 m depth. Actual evapotranspiration in the future will diminish according to four of the five models due to drier soil conditions. Despite their significant differences, the five hydrologic models responded similarly to the reduced precipitation and increased temperatures predicted by the climate models, and lend strong support to a future scenario of increased water shortages for this region of the Mediterranean basin. The multimodel framework adopted for this study allows estimation of the agreement between the five hydrologic models and between the four climate models. Pairwise comparison of the climate and hydrologic models is shown for the reference and future periods using a recently proposed metric that scales the Pearson correlation coefficient with a factor that accounts for systematic differences between datasets. The results from this analysis reflect the key structural differences between the hydrologic models, such as a representation of both vertical and lateral subsurface flow (CATHY, TOPKAPI, and tRIBS) and a detailed treatment of vegetation processes (SWAT and WASIM).

Flood simulation and parameter calibration of small watershed in hilly area based on HEC-HMS model

The rivers in the hill area have a larger drop, and heavy rains are liable to form mountain floods. Flood calculation in small watershed is a key link in the prevention of flash floods. Taking the Xueye Lake basin in Laicheng District as the research object, HEC-HMS was used to establish the semi-distributed hydrological model of the hill basin to calculate the rainfall-runoff and flood routing process. Based on the historical flood elevations of three typical floods, the sub-basin parameters were calibrated using the trial-and-error method. According to the flow data of the basin outlet, the peak-weighted RMS error function was selected as the objective function, and the Nelder-Mead optimization algorithm was used to estimate the overall watershed parameters. Rainfall and flow data for two floods were used to verify model accuracy. The results show that the relative errors between peak discharge and runoff depth are less than 20%. The model has good applicability to the flood simulation of the Xueye Lake Basin and can play an actual role in the mountain flood warning forecast. The proposed lumped parameter calibration and modeling method can provide reference for flood simulation in other small basins.

WATER MANAGEMENT OF RIVER ESTUARY FOR THE PREPARATION OF ECOTOURISM IN COASTAL AREA OF BALI PROVINCE

Surface water flowing in the river is a resource of useful raw water to meet the needs of society and as irrigation water is managed by Subak in Bali, Indonesia. Bali has experienced water deficit, along with the increasing number of inhabitants and tourism activities. Results of research of the Ministry of Environment (MOE, 2009) stated that Bali has experienced water deficit of 7.5 billion m3/year in 2000 and 2015 deficit is estimated at as much as 27.6 billion m3 of water/year. The purpose of this research was to evaluate the potential of water in the estuary Saba in order to support ecotourism in coastal areas of the province of Bali and formulating water resource management scheme for coastal areas in Buleleng regency. This research uses quantitative methods with the research location is in the Saba river estuary in Buleleng Regency. Data collected consist of primary data and secondary data. Simulation models for water resources management and statistical analysis using software RIBASIM (River Basin Simulation). As a result of this research is the potential of water in the estuary Saba. The result of measurements in the dry season (September 2013) is amounted to 0.156 m3/sec and in the rainy season (January 2014) of 1,023 m3/sec. Potential water in Saba river estuary based on the simulation of RIBASIM is 9.34 million m3/year, can be used as society water domestic for 81 851 inhabitants, for the water industry (hotel) is 1364 rooms, amounted to 2 ha of fish pond water and for irrigation water (agricultural) is 148 ha. Results of water quality research to the smell, color, temperature, turbidity meet quality standards, while taste, and salinity do not meet quality standards. For the chemical aspect, that is pH and detergent meet quality standards while for BOD and COD does not meet the water quality standard Class I. In terms of biology, total coliform does not meet the quality standards of class I. Saba River water potential for ground water of 7.46 million m3 (6%), residual water irrigation (Return Flow) amounted to 54.74 million m3 (41%) and the balance/allocation of water in an area (water District) amounted to 71.54 million m3 (53%). Water resources management in the Saba River estuary for the water potential in the river estuary can be managed by making reservoirs (reservoir), and dam movement and arrangement of the beach.

Flood hydrograph simulation in ungaged basins: modeling linear–nonlinear storage-discharge relationships in a semiarid mountain region

ABSTRACTFor the purpose of flood mitigation in a mountain region, this study aims to evaluate the degree of nonlinearity in the hydrologic storage-discharge relationship. The study area includes a mesoscale catchment, its headwater subcatchment, and its large-scale parent basin in the Zagros mountain region of southwestern Iran. Rainfall events are divided into two variable classes, Low Temporal (LT) and High Temporal (HT), based on their heterogeneity across time. For Low Temporal rainfall events, the mesoscale catchment and its headwater subcatchment show strong nonlinear behavior, but their responses tend to be less nonlinear for High Temporal rainfall events. Meanwhile, for High Temporal events, soil moisture has a dominant role in catchment response. On the other hand, a different perspective is drawn for the larger basin because a strong nonlinear response is obtained for all events regardless of temporal heterogeneities and soil moisture conditions, emphasizing the filtering effect of catchment extent on the rainfall–runoff process.

Modelling hydrologic and hydrodynamic processes in basins with large semi-arid wetlands

Hydrological and hydrodynamic models are core tools for simulation of large basins and complex river systems associated to wetlands. Recent studies have pointed towards the importance of online coupling strategies, representing feedbacks between floodplain inundation and vertical hydrology. Especially across semi-arid regions, soil-floodplain interactions can be strong. In this study, we included a two-way coupling scheme in a large scale hydrological-hydrodynamic model (MGB) and tested different model structures, in order to assess which processes are important to be simulated in large semi-arid wetlands and how these processes interact with water budget components. To demonstrate benefits from this coupling over a validation case, the model was applied to the Upper Niger River basin encompassing the Niger Inner Delta, a vast semi-arid wetland in the Sahel Desert. Simulation was carried out from 1999 to 2014 with daily TMPA 3B42 precipitation as forcing, using both in-situ and remotely sensed data for calibration and validation. Model outputs were in good agreement with discharge and water levels at stations both upstream and downstream of the Inner Delta (Nash-Sutcliffe Efficiency (NSE) >0.6 for most gauges), as well as for flooded areas within the Delta region (NSE = 0.6; r = 0.85). Model estimates of annual water losses across the Delta varied between 20.1 and 30.6 km3/yr, while annual evapotranspiration ranged between 760 mm/yr and 1130 mm/yr. Evaluation of model structure indicated that representation of both floodplain channels hydrodynamics (storage, bifurcations, lateral connections) and vertical hydrological processes (floodplain water infiltration into soil column; evapotranspiration from soil and vegetation and evaporation of open water) are necessary to correctly simulate flood wave attenuation and evapotranspiration along the basin. Two-way coupled models are necessary to better understand processes in large semi-arid wetlands. Finally, such coupled hydrologic and hydrodynamic modelling proves to be an important tool for integrated evaluation of hydrological processes in such poorly gauged, large scale basins. We hope that this model application provides new ways forward for large scale model development in such systems, involving semi-arid regions and complex floodplains.

Perturbations in the initial soil moisture conditions: Impacts on hydrologic simulation in a large river basin

Real time hydrologic forecasting requires near accurate initial condition of soil moisture; however, continuous monitoring of soil moisture is not operational in many regions, such as, in Ganga basin, extended in Nepal, India and Bangladesh. Here, we examine the impacts of perturbation/error in the initial soil moisture conditions on simulated soil moisture and streamflow in Ganga basin and its propagation, during the summer monsoon season (June to September). This provides information regarding the required minimum duration of model simulation for attaining the model stability. We use the Variable Infiltration Capacity model for hydrological simulations after validation. Multiple hydrologic simulations are performed, each of 21 days, initialized on every 5th day of the monsoon season for deficit, surplus and normal monsoon years. Each of these simulations is performed with the initial soil moisture condition obtained from long term runs along with positive and negative perturbations. The time required for the convergence of initial errors is obtained for all the cases. We find a quick convergence for the year with high rainfall as well as for the wet spells within a season. We further find high spatial variations in the time required for convergence; the region with high precipitation such as Lower Ganga basin attains convergence at a faster rate. Furthermore, deeper soil layers need more time for convergence. Our analysis is the first attempt on understanding the sensitivity of hydrological simulations of Ganga basin on initial soil moisture conditions. The results obtained here may be useful in understanding the spin-up requirements for operational hydrologic forecasts.

Hydrological Simulation of Small River Basins in Northern Kyushu, Japan, During the Extreme Rainfall Event of July 5–6, 2017

Extreme rainfall and associated flooding are common during the summer in Japan. Heavy rain caused extensive damage in many parts of Kyushu, Japan, on July 5–6, 2017. Many small mountainous river basins were subject to the core of this heavy rainfall event and were flooded, but no hydrological measurements were taken in most of these flooded basins during the event. There are few gauging stations in this mountainous region, and most that do exist are designed to monitor the larger watersheds. Consequently, it is difficult to determine the hydrological properties of the small subbasins within these larger watersheds. Therefore, to improve our understanding of the basic hydrological processes that affect small ungauged mountain river basins during periods of intense rainfall, a quasi-distributed model (i.e. the Hydrologic Engineering Center-Hydrologic Modeling System, HEC-HMS) was used in this study. The Hikosan (area: 65 km2) and Akatani (area: 21 km2) mountainous river basins were selected for the hydrological simulations. The model was validated using the Hikosan River basin because observational data are available from the outlet of this basin. However, there is no record of any hydrological observations for the Akatani River basin. Therefore, reference parameters from the Hikosan River basin were used for hydrological analysis of the Akatani River basin. This was possible because the basins are close to one another and have similar physiographic and topographic properties. The simulations of both basins, and the associated uncertainties, are discussed in detail in this paper. Based on the hydrological simulations, an attempt was made to analyze the maximum flood discharge caused by the event. The results generated using this approach to hydrological simulations in small ungauged basins could contribute to the management of water resources in these and other river basins during future extreme rain events.

Flood Routing Simulation and Management in Hydrologic Basins with Artificial Reservoirs—The Case of Arda River

Major flood events occurred in the Arda River region in the last decades with great economic, social and environmental effects. A specific software package has been developed for the simulation of the flood runoff and routing process of the transboundary Arda River basin. The software package is taking into account the existence of the three cascade Bulgarian reservoirs aiming to flood protection and power optimization. Inflow estimations for duration of five days ahead and initial water levels at the three reservoirs are imported at the beginning of the simulation. The management tool includes all the alternative operation modes of hydropower plants, water released from spillways, and river and reservoir flow characteristics in order to optimize the total system (power generation and flooding costs) during the flood event. The developed software is also an efficient tool for the establishment of a flood warning system.

Развитие сибирской ландшафтно-гидрологической школы

We have considered the distinctive features of the Siberian School of Landscape Hydrology formed in 1970s –1980s in Irkutsk in the Institute of Geography of Siberia and the Far East of the Siberian Branch of the USSR Academy of Sciences, especially in respect of basic experimental research, extensive use of hydrological indication methods, basin concept, and landscape/hydrological mapping. The experience of implementing the approach in practical development is stated. It is shown how the landscape-hydrological approach has been successfully applied in the hydrological/morphological analysis of deltas, in flow and hydro/chemical regime simulation in small river basins, in the study of dangerous hydrological processes, in water protection and recreational zoning, and in the atlas mapping of the Baikal region in the past decade.

Uncertainty from the choice of microphysics scheme in convection-permitting models significantly exceeds aerosol effects

Abstract. This study investigates the hydrometeor development and response to cloud droplet number concentration (CDNC) perturbations in convection-permitting model configurations. We present results from a real-data simulation of deep convection in the Congo basin, an idealised supercell case, and a warm-rain large-eddy simulation (LES). In each case we compare two frequently used double-moment bulk microphysics schemes and investigate the response to CDNC perturbations. We find that the variability among the two schemes, including the response to aerosol, differs widely between these cases. In all cases, differences in the simulated cloud morphology and precipitation are found to be significantly greater between the microphysics schemes than due to CDNC perturbations within each scheme. Further, we show that the response of the hydrometeors to CDNC perturbations differs strongly not only between microphysics schemes, but the inter-scheme variability also differs between cases of convection. Sensitivity tests show that the representation of autoconversion is the dominant factor that drives differences in rain production between the microphysics schemes in the idealised precipitating shallow cumulus case and in a subregion of the Congo basin simulations dominated by liquid-phase processes. In this region, rain mass is also shown to be relatively insensitive to the radiative effects of an overlying layer of ice-phase cloud. The conversion of cloud ice to snow is the process responsible for differences in cold cloud bias between the schemes in the Congo. In the idealised supercell case, thermodynamic impacts on the storm system using different microphysics parameterisations can equal those due to aerosol effects. These results highlight the large uncertainty in cloud and precipitation responses to aerosol in convection-permitting simulations and have important implications not only for process studies of aerosol–convection interaction, but also for global modelling studies of aerosol indirect effects. These results indicate the continuing need for tighter observational constraints of cloud processes and response to aerosol in a range of meteorological regimes.