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Agrawal, Niraj Kumar, Anil Kumar Lohani und N. K. Goel. „Physiographic Analysis of Tehri Dam Catchment and Development of GIUH Based Nash Model for Ungauged Rivers“. Current World Environment 14, Nr. 2 (24.06.2019): 215–30. http://dx.doi.org/10.12944/cwe.14.2.06.
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Advanced information about incoming flows is required for operation of a variety of hydraulic structures including multipurpose storage hydropower projects. Inflow forecasts are used for optimum power generation during non -monsoon season and operation of gates and spillways during the flood season. In order to develop an inflow forecasting system for a reservoir, it has been observed that many a times number of ungauged rivers directly falling into the reservoirs are not accounted for. Such is the case for the Tehri Reservoir, where 16 small rivers/tributaries which are directly contributing to Tehri reservoir are ungauged. In the present study an attempt has been made to carry out physiographic objective Tehri catchment and to develop Geomorphological Instantaneous Unit Hydrograph (GIUH) for ungauged rivers/tributaries directly falling into the reservoir. GIUH developed for the ungauged rivers can be used to simulate the runoff from all the 16 ungauged rivers. Combining these GIUH models with a hydrological model of the other gauged rivers of the Tehri Catchment in the form of a network model provides a complete rainfall-runoff model. Thus, this study provides a useful input for the development of inflow forecasting model for the Tehri Dam as the network model can be used as flood forecasting model.
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Bonasia, Rosanna, und Mackendy Ceragene. „Hydraulic Numerical Simulations of La Sabana River Floodplain, Mexico, as a Tool for a Flood Terrain Response Analysis“. Water 13, Nr. 24 (09.12.2021): 3516. http://dx.doi.org/10.3390/w13243516.
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The floodplain of La Sabana River, Guerrero State, Mexico, was subject to disastrous floods due to the passage of extreme weather phenomena. This is a situation facing many ungauged rivers in Mexico, as well as in other developing countries, where increased urbanization and a lack of monitoring systems make many inhabited areas more vulnerable to flooding. The purpose of this work is to provide a tool for determining the flood terrain response to flooding based on a hydraulic study. This methodology combines a hydrological analysis of the river basin with the floodplain hydraulic study for the precise identification of overflow points and the resulting flood levels. Results show that, for an ungauged river, hydraulic analysis is an essential tool for determining the main potential flood points and establishing whether the river has the capacity to contain floods. Specifically, it is shown that La Sabana River is predisposed to overflow long before the river reaches its maximum flow, even in correspondence with more frequent flood scenarios. This study shows a further application that a hydraulic model can have to improve flood risk preparedness for ungauged rivers of regions where other types of monitoring tools cannot be used.
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Lou, Hezhen, Pengfei Wang, Shengtian Yang, Fanghua Hao, Xiaoyu Ren, Yue Wang, Liuhua Shi, Juan Wang und Tongliang Gong. „Combining and Comparing an Unmanned Aerial Vehicle and Multiple Remote Sensing Satellites to Calculate Long-Term River Discharge in an Ungauged Water Source Region on the Tibetan Plateau“. Remote Sensing 12, Nr. 13 (06.07.2020): 2155. http://dx.doi.org/10.3390/rs12132155.
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Research into global water resources is challenged by the lack of ground-based hydrometric stations and limited data sharing. It is difficult to collect good quality, long-term information about river discharges in ungauged regions. Herein, an approach was developed to determine the river discharges of 24 rivers in ungauged regions on the Tibetan Plateau on a long-term scale. This method involved coupling the Manning–Strickler formula, and data from an unmanned aerial vehicle (UAV) and the Gaofen-2, SPOT-5, and Sentinel-2 satellites. We also compared the discharges calculated by using the three satellites’ data. Fundamental information about the rivers was extracted from the UAV data. Comparison of the discharges calculated from the in-situ measurements and the UAV data gave an R2 value of 0.84, an average NSE of 0.79, and an RMSE of 0.11 m3/s. The river discharges calculated with the GF-2 remote sensing data and the in-situ experiments for the same months were compared and the R2, RMSE, and the NSE were 0.80, 1.8 m3/s, and 0.78, respectively. Comparing the discharges calculated over the long term from the measured in-situ data and the SPOT-5 and Sentinel-2 data gave R2 values of 0.93 and 0.92, and RMSE values of 2.56 m3/s and 3.16 m3/s, respectively. The results showed that the GF-2 and UAV were useful for calculating the discharges for low-flow rivers, while the SPOT-5 or the Sentinel-2 satellite gave good results for high-flow river discharges in the long-term. Our results demonstrate that the discharges in ungauged tributaries can be reliably estimated in the long-term with this method. This method extended the previous research, which described river discharge only in one period and provided more support to the monitoring and management of the tributaries in ungauged regions.
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Hou, Jiawei, Albert I. J. M. van Dijk, Luigi J. Renzullo und Robert A. Vertessy. „Using modelled discharge to develop satellite-based river gauging: a case study for the Amazon Basin“. Hydrology and Earth System Sciences 22, Nr. 12 (11.12.2018): 6435–48. http://dx.doi.org/10.5194/hess-22-6435-2018.
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Abstract. River discharge measurements have proven invaluable to monitor the global water cycle, assess flood risk, and guide water resource management. However, there is a delay, and ongoing decline, in the availability of gauging data and stations are highly unevenly distributed globally. While not a substitute for river discharge measurement, remote sensing is a cost-effective technology to acquire information on river dynamics in situations where ground-based measurements are unavailable. The general approach has been to relate satellite observation to discharge measured in situ, which prevents its use for ungauged rivers. Alternatively, hydrological models are now available that can be used to estimate river discharge globally. While subject to greater errors and biases than measurements, model estimates of river discharge do expand the options for applying satellite-based discharge monitoring in ungauged rivers. Our aim was to test whether satellite gauging reaches (SGRs), similar to virtual stations in satellite altimetry, can be constructed based on Moderate Resolution Imaging Spectroradiometer (MODIS) optical or Global Flood Detection System (GFDS) passive microwave-derived surface water extent fraction and simulated discharge from the World-Wide Water (W3) model version 2. We designed and tested two methods to develop SGRs across the Amazon Basin and found that the optimal grid cell selection method performed best for relating MODIS and GFDS water extent to simulated discharge. The number of potential river reaches to develop SGRs increases from upstream to downstream reaches as rivers widen. MODIS SGRs are feasible for more river reaches than GFDS SGRs due to its higher spatial resolution. However, where they could be constructed, GFDS SGRs predicted discharge more accurately as observations were less affected by cloud and vegetation. We conclude that SGRs are suitable for automated large-scale application and offer a possibility to predict river discharge variations from satellite observations alone, for both gauged and ungauged rivers.
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Yang, Shengtian, Chaojun Li, Hezhen Lou, Pengfei Wang, Juan Wang und Xiaoyu Ren. „Performance of an Unmanned Aerial Vehicle (UAV) in Calculating the Flood Peak Discharge of Ephemeral Rivers Combined with the Incipient Motion of Moving Stones in Arid Ungauged Regions“. Remote Sensing 12, Nr. 10 (18.05.2020): 1610. http://dx.doi.org/10.3390/rs12101610.
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Ephemeral rivers are vital to ecosystem balance and human activities as essential surface runoff, while convenient and effective ways of calculating the peak discharge of ephemeral rivers are scarce, especially in ungauged areas. In this study, a new method was proposed using an unmanned aerial vehicle (UAV) combined with the incipient motion of stones to calculate the peak discharge of ephemeral rivers in northwestern China, a typical arid ungauged region. Two field surveys were conducted in dry seasons of 2017 and 2018. Both the logarithmic and the exponential velocity distribution methods were examined when estimating critical initial velocities of moving stones. Results reveal that centimeter-level orthoimages derived from UAV data can demonstrate the movement of stones in the ephemeral river channel throughout one year. Validations with peak discharge through downstream culverts confirmed the effectiveness of the method. The exponential velocity distribution method performs better than the logarithmic method regardless of the amount of water through the two channels. The proposed method performs best in the combination of the exponential method and the river channel with evident flooding (>20 m3/s), with the relative accuracy within 10%. In contrast, in the river channel with a little flow (around 1 m3/s), the accuracies are weak because of the limited number of small moving stones found due to the current resolution of UAV data. The poor performance in the river channel with a little flow could further be improved by identifying smaller moving stones, especially using UAV data with better spatial resolution. The presented method is easy and flexible to apply with appropriate accuracy. It also has great potential for extensive applications in obtaining runoff information of ephemeral rivers in ungauged regions, especially with the quick advance of UAV technology.
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Yang, Shengtian, Juan Wang, Pengfei Wang, Tongliang Gong und Huiping Liu. „Low Altitude Unmanned Aerial Vehicles (UAVs) and Satellite Remote Sensing Are Used to Calculated River Discharge Attenuation Coefficients of Ungauged Catchments in Arid Desert“. Water 11, Nr. 12 (13.12.2019): 2633. http://dx.doi.org/10.3390/w11122633.
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The arid desert ecosystem is very fragile, and the change of its river discharge has a direct impact on irrigation and natural environment. River discharge attenuation coefficients is a key index to reveal the stability of desert river ecosystem. However, due to the harsh conditions in desert areas, it is difficult to establish a hydrological station to obtain data and calculate the attenuation coefficients, so it is urgent to develop new methods to master the attenuation coefficients of rivers. In this study, Taklamakan desert river was selected as the research area, and the river discharge of the desert river were estimated by combining low-altitude UAV and satellite remote sensing technology, so as to calculate the attenuation status of the river in its natural state. Combined with satellite remote sensing, the surface runoff in the desert reaches of the Hotan River from 1993 to 2017 were estimated. The results showed that the base of runoff attenuation in the lower reaches of the Hotan River is 40%. Coupled UAV and satellite remote sensing technology can provide technical support for the study of surface runoff in desert rivers within ungauged basins. Using UAV and satellite remote sensing can monitor surface runoff effectively providing important reference for river discharge monitoring in ungauged catchments.
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Basnet, Keshav, Deepak Acharya, Krishna Prasad Bhandari, Suraj Lamichhane und Biwas Babu Sadadev. „Floodplain mapping of an ungauged river: A case study on Seti River in Pokhara, Nepal“. Himalayan Journal of Applied Science and Engineering 4, Nr. 2 (25.01.2024): 23–39. http://dx.doi.org/10.3126/hijase.v4i2.62185.
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Settlements and infrastructures along the banks of Seti River in Pokhara, Nepal are at high risk of flood. Floodplain mapping for ungauged Seti River is not straightforward like the one for gauged rivers. Main goal of this study was to prepare floodplain maps along the ungauged Seti River in Pokhara, as a case study, using one-dimensional HEC-RAS model. First, catchment area ratio (CAR) method was applied to find annual flow in ungauged Seti River based on flow data of gauged Mardi station. Once the annual maximum flow was estimated for sufficient time length (i.e., 42 years), peak flood was predicted using Gumbel method for various reaches of Seti River within Pokhara. Thus, estimated peak floods were also compared with the peak floods predicted using Gumbel method based on the annual flow data of Tanahu station. As the specific discharge observed to be comparable with each other (difference ≤ 2.68%), CAR method found be a reliable one that is useful for ungauged river. Then, Cowan’s approach was applied to estimate Manning’s roughness coefficient (n) and used it for calibration of HEC-RAS model. Cowan approach found to be a best alternative for ungauged river as the comparison of modelled flow depth with measured flow depth yielded only 3.82% difference. Finally, 1D hydraulic modelling was performed using calibrated HEC-RAS model with available 12.5 m resolution DEM terrain data. Floodplain maps were prepared based on the HEC-RAS simulation results coupled with Google Earth map. The flood inundation area within Pokhara was found to be 2.76, 3.05, and 3.59 Km2 for the peak flood of 20, 50, and 100 years return periods, respectively. Moreover, Laltin Bazar and Gaighat areas were identified to be at high risk of flood such that these areas found to be inundated with 20 or greater years return period floods, compared to Ramghat area which was observed to be flooded with the peak flood of 50 or more years return period. Floodplain maps of this study could be used for preparing flood hazard maps, planning infrastructures, and flood management.
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Gorbachova, Liudmyla, und Borys Khrystyuk. „Calculation Approaches of the Probable Maximum Discharge of Spring Flood at Ungauged Sites in the Southern Buh River Basin, Ukraine“. Annals of Valahia University of Targoviste, Geographical Series 18, Nr. 2 (01.10.2018): 107–20. http://dx.doi.org/10.2478/avutgs-2018-0012.
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Abstract Calculation of probable maximum discharge of spring flood are the great practical importance, since it is the basis to plan and design of different hydraulic structures, such as dams, culverts, urban and agriculture drainage systems, etc. Thus, the updating of the methodical approaches and parameters of the empirical formulas which using in the determining of the probable maximum discharge of spring flood at ungauged sites of the river basin is an actual task. In this paper for the Southern Buh River Basin were updated the parameters of the reduction formula and the limiting intensity formula of streamflow which are using to calculated of the probable maximum discharge of spring flood at ungauged basin in Ukraine. The presented results illustrate that parameters of empirical formulas that were calculated according to modern observation series (since the beginning of the observations to 2010) in comparison with previously received (since the beginning of the observations to 1980) have significant changes. We found out that it is due to cyclical of the long-term fluctuations of the maximum streamflow of spring flood in the Southern Buh River Basin. We also illustrated that for the small ungauged basins have the difficulties with the choice of rivers-analogues.
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Archfield, S. A., P. A. Steeves, J. D. Guthrie und K. G. Ries III. „A web-based software tool to estimate unregulated daily streamflow at ungauged rivers“. Geoscientific Model Development Discussions 5, Nr. 3 (31.08.2012): 2503–26. http://dx.doi.org/10.5194/gmdd-5-2503-2012.
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Abstract. Streamflow information is critical for solving any number of hydrologic problems. Often times, streamflow information is needed at locations which are ungauged and, therefore, have no observations on which to base water management decisions. Furthermore, there has been increasing need for daily streamflow time series to manage rivers for both human and ecological functions. To facilitate negotiation between human and ecological demands for water, this paper presents the first publically-available, map-based, regional software tool to interactively estimate daily streamflow time series at any user-selected ungauged river location. The map interface allows users to locate and click on a river location, which then returns estimates of daily streamflow for the location selected. For the demonstration region in the northeast United States, daily streamflow was shown to be reliably estimated by the software tool, with efficiency values computed from observed and estimated streamflows ranging from 0.69 to 0.92. The software tool provides a general framework that can be applied to other regions for which daily streamflow estimates are needed.
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Nigussie, Getenet, Mamaru A. Moges, Michael M. Moges und Tammo S. Steenhuis. „Assessment of Suitable Land for Surface Irrigation in Ungauged Catchments: Blue Nile Basin, Ethiopia“. Water 11, Nr. 7 (15.07.2019): 1465. http://dx.doi.org/10.3390/w11071465.
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Planning and decision making for new irrigation development projects requires the systematic assessment of irrigable land together with available water resources. The data required are usually not available in developing countries, and therefore a method was developed for quantifying surface water resources and potentially irrigable land in ungauged watersheds in the Upper Blue Nile Basin using Soil and Water Assessment Tool (SWAT) model and Multi-Criterion Decision Evaluation (MCDE). The method was tested using the Lah river basin in the Jabitenan district and then applied in the whole area, including ungauged areas. In MCDE, soil type, slope, land use, and river proximity were considered. Onion, Cabbage and Tomato were grown on the identified irrigable areas. The predicted monthly stream discharge agreed well with observed values, with Nash and Sutcliffe efficiencies of 0.87 during calibration and 0.68 for validation. The SWAT model calibrated parameters from the gauged catchment were used to simulate the discharge of the ungauged catchments. The potential irrigable land was determined in Jabitenan woreda and included the Rivers like Birr, Tikurwuha, Gunagun, Leza Lah, Geray, Arara, Debolah, Guysa, and Silala, with an area of 460 km2. By evaluating gross irrigation demand of irrigable land with available flow in rivers (both observed and simulated), the actual surface irrigation potential was 47 km2. The main limitation for surface irrigation in all districts was the available water and not the land suitable for irrigation. Therefore, the study suggests that in order to irrigate a greater portion of the irrigable land, water should be stored during the monsoon rain phase for use in the last part of the dry phase.
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Aga, Alemu, Assefa Melesse und Bayou Chane. „Estimating the Sediment Flux and Budget for a Data Limited Rift Valley Lake in Ethiopia“. Hydrology 6, Nr. 1 (23.12.2018): 1. http://dx.doi.org/10.3390/hydrology6010001.
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Information on sediment concentration in rivers is important for the design and management of reservoirs. In this paper, river sediment flux and siltation rate of a rift valley lake basin (Lake Ziway, Ethiopia) was modeled using suspended sediment concentration (SSC) samples from four rivers and lake outlet stations. Both linear and non-linear least squares log–log regression methods were used to develop the model. The best-fit model was tested and evaluated qualitatively by time-series plots, quantitatively by using watershed model evaluation statistics, and validated by calculating the prediction error. Sediment yield (SY) of ungauged rivers were assessed by developing and using a model that includes catchment area, slope, and rainfall, whereas bedload was estimated. As a result, the gross annual SY transported into the lake was 2.081 Mton/year. Annually, 0.178 Mton/year of sediment is deposited in floodplains with a sediment trapping rate of 20.6%, and 41,340 ton/year of sediment leaves the lake through the Bulbula River. The annual sediment deposition in the lake is 2.039 Mton/year with a mean sediment trapping efficiency of 98%. Based on the established sediment budget with average rainfall, the lake will lose its volume by 0.106% annually and the lifetime of Lake Ziway will be 947 years. The results show that the approach used can be replicated at other similar ungauged watersheds. As one of the most important sources of water for irrigation in the country, the results can be used for planning and implementing a lake basin management program targeting upstream soil erosion control.
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P. C., Shakti, Tsuyoshi Nakatani und Ryohei Misumi. „Analysis of Flood Inundation in Ungauged Mountainous River Basins: A Case Study of an Extreme Rain Event on 5–6 July 2017 in Northern Kyushu, Japan“. Journal of Disaster Research 13, Nr. 5 (01.10.2018): 860–72. http://dx.doi.org/10.20965/jdr.2018.p0860.
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The heavy rainfall event that occurred on 5–6 July 2017 in Northern Kyushu, Japan, caused extensive flooding across several mountainous river basins and resulted in fatalities and extensive damage to infrastructure along those rivers. For the periods before and during the extreme event, there are no hydrological observations for many of the flooded river basins, most of which are small and located in mountainous regions. We used the Gridded Surface Subsurface Hydrologic Analysis (GSSHA) model, a physically based model, to acquire more detailed information about the hydrological processes in the flood-affected ungauged mountain basins. We calibrated the GSSHA model using data from an adjacent gauged river basin, and then applied it to several small ungauged basins without changing the parameters of the model. We simulated the gridded flow and generated a map of the possible maximum flood depth across the basins. By comparing the extent of flood-affected areas from the model with data of the Japanese Geospatial Information Authority (GSI), we found that the maximum flood inundation areas of the river networks estimated by the GSSHA model are sometimes less than those estimated by the GSI, as the influence of landslides and erosion was not considered in the modeling. The model accuracy could be improved by taking these factors into account, although this task would be challenging. The results indicated that simulations of flood inundation in ungauged mountain river basins could contribute to disaster management during extreme rain events.
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Khasmakhi, Hadis Pakdel, Majid Vazifedoust, Safar Marofi und Abdollah Taheri Tizro. „Simulation of river discharge in ungauged catchments by forcing GLDAS products to a hydrological model (a case study: Polroud basin, Iran)“. Water Supply 20, Nr. 1 (05.11.2019): 277–86. http://dx.doi.org/10.2166/ws.2019.160.
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Abstract Due to unavailability of sufficient discharge data for many rivers, an appropriate approach is required to provide accurate data for estimating discharge in ungauged watersheds. In this study, Global Land Data Assimilation System (GLDAS) datasets were integrated with Hydrologic Engineering Center Hydrologic Modeling System (HEC-HMS) to simulate the outlet river discharge in Polroud watershed, located in the North of Iran. Temperature and precipitation products generated by GLDAS were calibrated using regression analysis based on observation data for the period of 2004–2006. Then, river discharge was simulated by using HEC-HMS based on two different datasets (GLDAS meteorological product and gauged data) on the scale of the basin for the same period. The results clearly indicated that the forcing of GLDAS data into HEC-HMS model leads to promising results with acceptable correlation with observed data. Although, in comparison with direct GLDAS runoff products, the proposed approach improved the accuracy of river discharge, the problem of underestimation still reduces the expected accuracy. Because of global accessibility, GLDAS datasets would be a good alternative in ungauged or poorly gauged watersheds.
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Biondi, Filippo, Angelica Tarpanelli, Pia Addabbo, Carmine Clemente und Danilo Orlando. „Pixel Tracking to Estimate Rivers Water Flow Elevation Using Cosmo-SkyMed Synthetic Aperture Radar Data“. Remote Sensing 11, Nr. 21 (02.11.2019): 2574. http://dx.doi.org/10.3390/rs11212574.
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The lack of availability of historical and reliable river water level information is an issue that can be overcome through the exploitation of modern satellite remote sensing systems. This research has the objective of contributing in solving the information-gap problem of river flow monitoring through a synthetic aperture radar (SAR) signal processing technique that has the capability to perform water flow elevation estimation. This paper proposes the application of a new method for the design of a robust procedure to track over the time double-bounce reflections from bridges crossing rivers to measure the gap space existing between the river surface and bridges. Specifically, the difference in position between the single and double bounce is suitably measured over the time. Simulated and satellite temporal series of SAR data from COSMO-SkyMed data are compared to the ground measurements recorded for three gauges sites over the Po and Tiber Rivers, Italy. The obtained performance indices confirm the effectiveness of the method in the estimation of water level also in narrow or ungauged rivers.
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Archfield, S. A., P. A. Steeves, J. D. Guthrie und K. G. Ries III. „Towards a publicly available, map-based regional software tool to estimate unregulated daily streamflow at ungauged rivers“. Geoscientific Model Development 6, Nr. 1 (28.01.2013): 101–15. http://dx.doi.org/10.5194/gmd-6-101-2013.
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Abstract. Streamflow information is critical for addressing any number of hydrologic problems. Often, streamflow information is needed at locations that are ungauged and, therefore, have no observations on which to base water management decisions. Furthermore, there has been increasing need for daily streamflow time series to manage rivers for both human and ecological functions. To facilitate negotiation between human and ecological demands for water, this paper presents the first publicly available, map-based, regional software tool to estimate historical, unregulated, daily streamflow time series (streamflow not affected by human alteration such as dams or water withdrawals) at any user-selected ungauged river location. The map interface allows users to locate and click on a river location, which then links to a spreadsheet-based program that computes estimates of daily streamflow for the river location selected. For a demonstration region in the northeast United States, daily streamflow was, in general, shown to be reliably estimated by the software tool. Estimating the highest and lowest streamflows that occurred in the demonstration region over the period from 1960 through 2004 also was accomplished but with more difficulty and limitations. The software tool provides a general framework that can be applied to other regions for which daily streamflow estimates are needed.
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Costelloe, J. F., J. T. Puckridge, J. R. W. Reid, J. Pritchard, P. Hudson, V. Bailey und M. Good. „Environmental flow requirements in arid zone rivers – a case study from the Lake Eyre Basin, central Australia“. Water Science and Technology 48, Nr. 7 (01.10.2003): 65–72. http://dx.doi.org/10.2166/wst.2003.0425.
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The ARIDFLO project takes a multi-disciplinary approach to the collection and analysis of data required to formulate appropriate environmental flow requirements for rivers in the Lake Eyre Basin. The key drivers of the ecological processes underpinning the health of these rivers are identified by modelling whole-of-ecosystem biological responses to hydrological events over a range of spatial and temporal scales. First, the hydrology of these poorly gauged (often ungauged) rivers needs to be modelled and validated to mimic real flow and inundation patterns at the catchment, reach and waterbody scale. Modelled and actual discharge data are then used to provide a suite of hydrological predictor variables which, in conjunction with other environmental variables, are used to model observed biotic responses. The key hydrologic and environmental drivers identified by the statistical models need to be taken into account when determining environmental flow requirements for these river systems. Further work is required to assess the predictive power of the models in the highly variable, complex systems of the Lake Eyre Basin rivers.
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Yusuf, Abdulganiyu, Romoke Ojo, Mohammed O. Idrees, Abdul-Lateef Balogun, Isa B. Salami und Ojogbane S. Sani. „Modelling flood hazards impacted by ungauged river in urbanised area using HEC-RAS and GIS“. Nigerian Journal of Technological Development 20, Nr. 2 (10.10.2023): 83–92. http://dx.doi.org/10.4314/njtd.v20i2.1405.
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Ilorin City is located downstream of Asa, Oyun and Awun River Basins. The Asa River is a major river that traverses the city and divides the metropolitan area into east and west, almost equally. The river often overflows its banks to inundate adjacent communities, influencing severe economic damage and impact on human lives. However, efforts to mitigate this have majorly been focused on dredging the Asa River channel which has not solved the problem. For an accurate spatial and temporal understanding of the risks of floods and their potential hazards, it is important to estimate floods using river hydrology. The objective of this study is to model steady flow of the rivers using flow data and to map flood-prone areas in Ilorin using HEC-RAS integrated with GIS. Using the HEC-GeoRAS extension in the GIS environment, the geometric data of the rivers were obtained from the 30 m resolution digital elevation model (DEM) and input into HEC-RAS applying Manning Co-efficient values of 0.04, 0.045, and 0.04. For each river, flow data (Q) was given as the upstream boundary condition while a normal depth of 0.001 was assigned for the downstream condition to model a steady flow and inundation extents. The result of the HEC-RAS model has shown the flood-prone areas along the river channels delineated. The floodplain map produced reveals the spatial distribution and extent of the high flood-risk areas in the Ilorin metropolis. The total flooded area covers approximately 60.95 km2 (18%) majorly along the river channels. This study has demonstrated that integration of hydraulic modelling using HEC-RAS and GIS process is capable of producing an inundation flood map with good accuracy that will aid in suggesting effective measures to mitigate the impact of flooding.
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Jakimavičius, Darius, Gintaras Adžgauskas, Diana Šarauskienė und Jūratė Kriaučiūnienė. „Climate Change Impact on Hydropower Resources in Gauged and Ungauged Lithuanian River Catchments“. Water 12, Nr. 11 (21.11.2020): 3265. http://dx.doi.org/10.3390/w12113265.
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Hydropower (potential and kinetic energy) is one of the most important renewable energy sources in the world. This energy is directly dependent on water resources and the hydrological cycle. Ongoing climate changes are likely to influence the availability/amount of this energy resource. The present study explores the relationship between climate changes and river runoff, projects future runoff in both gauged and ungauged river catchments, and then assesses how these alterations may affect the future hydropower resources in Lithuania. Runoff projections of the gauged rivers were evaluated applying Swedish Department of Climate hydrological model, and runoff of ungauged river catchments were estimated by created isoline maps of specific runoff. According to an ensemble of three climate models and two Representative Concentration Pathway scenarios, runoff and hydroelectric energy projections were evaluated for two future periods (2021–2040, 2081–2100). The results demonstrated a decrease in future river runoff. Especially significant changes are expected according to the most pessimistic RCP8.5 scenario at the end of the century. The projected changes are likely to bring a negative effect on hydropower production in the country. These findings could help understand what kind of benefits and challenges water resource managers may face in the future.
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Zhou, Mingtong, Yuchuan Guo, Ning Wang, Xuan Wei, Yunbao Bai und Huijing Wang. „Low-Altitude Remote Sensing Inversion of River Flow in Ungauged Basins“. Sustainability 14, Nr. 19 (07.10.2022): 12792. http://dx.doi.org/10.3390/su141912792.
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Runoff is closely related to human production, the regional environment, and hydrological characteristics. It is also an important basis for water cycle research and regional water resource development and management. However, obtaining hydrological information for uninformed river sections is complicated by harsh environments, limited transportation, sparse populations, and a low density of hydrological observation stations in the inland arid zone. Here, low-altitude remote sensing technology was introduced to combine riverbed characteristics through unmanned aerial vehicle (UAV) inversion with classical hydraulic equations for ungauged basins in the middle and lower reaches of the Keriya River, northwest China, and investigate the applicability of this method on wide and shallow riverbeds of inland rivers. The results indicated that the estimated average error of the low-altitude remote sensing flow was 8.49% (ranging 3.26–17.00%), with a root mean square error (RMSE) of 0.59 m3·s−1 across the six selected river sections, suggesting that this method has some applicability in the study area. Simultaneously, a method for estimating river flow based on the water surface width– and water depth–flow relationship curves for each section was proposed whereas the precise relationships were selected based on actual section attributes to provide a new method for obtaining runoff data in small- and medium-scale river areas where information is lacking.
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Kebede, Mulugeta Genanu, Lei Wang, Kun Yang, Deliang Chen, Xiuping Li, Tian Zeng und Zhidan Hu. „Discharge Estimates for Ungauged Rivers Flowing over Complex High-Mountainous Regions based Solely on Remote Sensing-Derived Datasets“. Remote Sensing 12, Nr. 7 (26.03.2020): 1064. http://dx.doi.org/10.3390/rs12071064.
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Reliable information about river discharge plays a key role in sustainably managing water resources and better understanding of hydrological systems. Therefore, river discharge estimation using remote sensing techniques is an ongoing research goal, especially in small, headwater catchments which are mostly ungauged due to environmental or financial limitations. Here, a novel method for river discharge estimation based entirely on remote sensing-derived parameters is presented. The model inputs include average river width, estimated from Landsat imagery by using the modified normalized difference water index (MNDWI) approach; average depth and velocity, based on empirical equations with inputs from remote sensing; channel slope from a high resolution shuttle radar topography mission digital elevation model (SRTM DEM); and channel roughness coefficient via further analysis and classification of Landsat images with support of previously published values. The discharge of the Lhasa River was then estimated based on these derived parameters and by using either the Manning equation (Model 1) or Bjerklie equation (Model 2). In general, both of the two models tend to overestimate discharge at moderate and high flows, and underestimate discharge at low flows. The overall performances of both models at the Lhasa gauge were satisfactory: comparisons with the observations yielded Nash–Sutcliffe efficiency coefficient (NSE) and R2 values ≥ 0.886. Both models also performed well at the upper gauge (Tanggya) of the Lhasa River (NSE ≥ 0.950) indicating the transferability of the methodology to river cross-sections with different morphologies, thus demonstrating the potential to quantify streamflow entirely from remote sensing data in poorly-gauged or ungauged rivers on the Tibetan Plateau.
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Gutry-Korycka, Małgorzata, Dariusz Woronko und Jarosław Suchożebrski. „Regional Conditions for Maximum Probable Discharge in Poland’s Rivers“. Miscellanea Geographica 14, Nr. 1 (01.12.2010): 145–67. http://dx.doi.org/10.2478/mgrsd-2010-0014.
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Abstract The purpose of this study was to obtain and verify the methods of catchment regionalization for annual maximum discharge. An identification of Polish rivers was performed based on regional frequency analyses including recognition of regions homogeneous with respect to their physical properties and river flow parameters. The results suggest a division into two regional groups: mountain and lowland catchments. Statistical tests verify the regionalization obtained and allow to calculate regional probability curves for these two catchment groups. The results obtained may be helpful in the analysis of floods in ungauged catchments and in those where hydrological observations were performed during a short period, especially when the dependence of the maximum probable flows on their physico-geographical features in catchments under analysis has been proved.
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Roy, Suvendu, und Biswaranjan Mistri. „Estimation of Peak Flood Discharge for an Ungauged River: A Case Study of the Kunur River, West Bengal“. Geography Journal 2013 (28.12.2013): 1–11. http://dx.doi.org/10.1155/2013/214140.
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Due to unavailability of sufficient discharge data for many rivers, hydrologists have used indirect methods for deriving flood discharge amount, that is, application of channel geometry and hydrological models, for the estimation of peak discharge in the selected ungauged river basin(s) in their research/project works. This paper has studied the estimation of peak flood discharge of the Kunur River Basin, a major tributary of the Ajay River in the lower Gangetic plain. To achieve this objective, field measurements, GIS technique, and several channel geometry equations are adopted. Three important geomorphic based hydrological models—manning’s equation, kinematic wave parameter (KWP), and SCS curve number (CN) method—have been used for computing peak discharge during the flood season, based on daily rainfall data of September, 2000. Peak discharges, calculated by different given models, are 239.44 m3/s, 204.08 m3/s, and 146.52 m3/s, respectively. The hydrograph has demonstrated the sudden increase with heavy rainfall from the 18th to the 22nd of September, 2000. As a result, a havoc flood condition was generated in the confluence zone of Ajay and Kunur Rivers. This hydrograph might be not only successful application for flood forecasting but also for management of the lower Ajay River Basin as well as the downstream area of Kunur Basin.
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Yu, Zexing, Xiaohong Chen und Jiefeng Wu. „Calibrating a Hydrological Model in an Ungauged Mountain Basin with the Budyko Framework“. Water 14, Nr. 19 (02.10.2022): 3112. http://dx.doi.org/10.3390/w14193112.
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Calibrating spatially distributed hydrological models in ungauged mountain basins is complicated due to the paucity of information and the uncertainty in representing the physical characteristics of a drainage area. In this study, an innovative method is proposed that incorporates the Budyko framework and water balance equation derived water yield (WYLD) in the calibration of the Soil and Water Assessment Tool (SWAT) with a monthly temporal resolution. The impact of vegetation dynamics (i.e., vegetation coverage) on Budyko curve shape parameter ω was considered to improve the Budyko calibration. The proposed approach is applied to the upstream Lancang-Mekong River (UL-MR), which is an ungauged mountain basin and among the world’s most important transboundary rivers. We compared the differences in SWAT model results between the different calibration approaches using percent bias (PBIAS), coefficient of determination (R2), and Nash–Sutcliffe efficiency (NSE) coefficient. The results demonstrated that the Budyko calibration approach exhibited a significant improvement against an unfitted priori parameter run (the non-calibration case) though it did not perform as good as fitting of the calibration by the observed streamflow. The NSE value increased by 44.59% (from 0.46 to 0.83), the R2 value increased by 2.30% (from 0.87 to 0.89) and the PBIAS value decreased by 55.67% (from 39.7 to 17.6) during the validation period at the drainage outlet (Changdu) station. The outcomes of the analysis confirm the potential of the proposed Budyko calibration approach for runoff predictions in ungauged mountain basins.
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Zlatanović, N., M. Stefanović, M. Milojević und J. Čotrić. „Automated hydrologic analysis of ungauged basins in Serbia using open source software“. Water Practice and Technology 9, Nr. 4 (01.12.2014): 445–49. http://dx.doi.org/10.2166/wpt.2014.047.
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Drainage basins are for the most part ungauged or poorly gauged not only in Serbia but in most parts of the world, usually due to insufficient funds, but also the decommission of river gauges in upland catchments to focus on downstream areas which are more populated. Design discharges are needed for these rivers where no streamflow data are available, for various applications. Examples include river training works for flood protection measures or erosion control, design of culverts, water supply facilities, small hydropower plants, etc. This study deals with the application of freely available and open source software and datasets for automating rainfall–runoff analysis of ungauged basins, applying geographical information systems techniques and programming to methodologies currently in use in hydrological practice. The geomorphometric module was tested on more than 100 catchments throughout Serbia (using a digital terrain model) and compared to manually calculated values (using topographic maps). The discharge estimation module was tested on 21 catchments where data were available and compared to results obtained by frequency analysis of measured discharges. The geomorphometric module of the calculation system showed excellent results, saving a great deal of time that would otherwise have been spent on manual processing of geospatial data, while the discharge estimation module showed a need for improved hydrological models.
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Piotrowski, Adam P., Jaroslaw J. Napiorkowski, Pawel M. Rowinski und Steve G. Wallis. „Evaluation of temporal concentration profiles for ungauged rivers following pollution incidents“. Hydrological Sciences Journal 56, Nr. 5 (Juli 2011): 883–94. http://dx.doi.org/10.1080/02626667.2011.583398.
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Yan, Bao-Wei, Yi-Xuan Zou, Yu Liu, Ran Mu, Hao Wang und Yi-Wei Tang. „Addressing Spatial Heterogeneity in the Discrete Generalized Nash Model for Flood Routing“. Water 13, Nr. 21 (07.11.2021): 3133. http://dx.doi.org/10.3390/w13213133.
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River flood routing is one of the key components of hydrologic modeling and the topographic heterogeneity of rivers has great effects on it. It is beneficial to take into consideration such spatial heterogeneity, especially for hydrologic routing models. The discrete generalized Nash model (DGNM) based on the Nash cascade model has the potential to address spatial heterogeneity by replacing the equal linear reservoirs into unequal ones. However, it seems impossible to obtain the solution of this complex high order differential equation directly. Alternatively, the strict mathematical derivation is combined with the deeper conceptual interpretation of the DGNM to obtain the heterogeneous DGNM (HDGNM). In this work, the HDGNM is explicitly expressed as a linear combination of the inflows and outflows, whose weight coefficients are calculated by the heterogeneous S curve. Parameters in HDGNM can be obtained in two different ways: optimization by intelligent algorithm or estimation based on physical characteristics, thus available to perform well in both gauged and ungauged basins. The HDGNM expands the application scope, and becomes more applicable, especially in river reaches where the river slopes and cross-sections change greatly. Moreover, most traditional routing models are lumped, whereas the HDGNM can be developed to be semidistributed. The middle Hanjiang River in China is selected as a case study to test the model performance. The results show that the HDGNM outperforms the DGNM in terms of model efficiency and smaller relative errors and can be used also for ungauged basins.
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Burgan, Halil Ibrahim, und Hafzullah Aksoy. „Annual flow duration curve model for ungauged basins“. Hydrology Research 49, Nr. 5 (12.02.2018): 1684–95. http://dx.doi.org/10.2166/nh.2018.109.
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AbstractA flow duration curve (FDC) plots the percentage of time that flow in a stream is equal to or exceeding a given value. In a gauged basin, it is obtained by sorting the observed flow from the largest to the smallest, and plotting against the corresponding exceedance probability. At ungauged basins where no data exist, the need for developing empirical methods emerges. This study aims at developing an FDC model for ungauged basins. The model is based on the normalized nondimensional annual mean flow quantiles. The annual mean flow is empirically calculated by a regression equation that takes drainage area and annual precipitation as input. Slope of the channel is additionally considered in the regression, however no better performance is achieved. Seyhan and Ceyhan basins in the Mediterranean region in southern Turkey are chosen as the study area. Data from 109 gauging stations are used for the calibration and validation of the model. Gauging stations on the tributaries are studied with a view to limiting anthropogenic activities on the rivers. Results of the application are found so promising that the model can be considered a good foundation for the development of FDCs at ungauged basins.
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Burgan, Halil Ibrahim, und Hafzullah Aksoy. „Daily flow duration curve model for ungauged intermittent subbasins of gauged rivers“. Journal of Hydrology 604 (Januar 2022): 127249. http://dx.doi.org/10.1016/j.jhydrol.2021.127249.
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Peñas, Francisco J., Barquín, José und Álvarez, César. „A comparison of modeling techniques to predict hydrological indices in ungauged rivers“. Limnetica, Nr. 37 (29.01.2018): 145–58. http://dx.doi.org/10.23818/limn.37.12.
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Vandaele, Remy, Sarah L. Dance und Varun Ojha. „Deep learning for automated river-level monitoring through river-camera images: an approach based on water segmentation and transfer learning“. Hydrology and Earth System Sciences 25, Nr. 8 (16.08.2021): 4435–53. http://dx.doi.org/10.5194/hess-25-4435-2021.
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Abstract. River-level estimation is a critical task required for the understanding of flood events and is often complicated by the scarcity of available data. Recent studies have proposed to take advantage of large networks of river-camera images to estimate river levels but, currently, the utility of this approach remains limited as it requires a large amount of manual intervention (ground topographic surveys and water image annotation). We have developed an approach using an automated water semantic segmentation method to ease the process of river-level estimation from river-camera images. Our method is based on the application of a transfer learning methodology to deep semantic neural networks designed for water segmentation. Using datasets of image series extracted from four river cameras and manually annotated for the observation of a flood event on the rivers Severn and Avon, UK (21 November–5 December 2012), we show that this algorithm is able to automate the annotation process with an accuracy greater than 91 %. Then, we apply our approach to year-long image series from the same cameras observing the rivers Severn and Avon (from 1 June 2019 to 31 May 2020) and compare the results with nearby river-gauge measurements. Given the high correlation (Pearson's correlation coefficient >0.94) between these results and the river-gauge measurements, it is clear that our approach to automation of the water segmentation on river-camera images could allow for straightforward, inexpensive observation of flood events, especially at ungauged locations.
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Sarhadi, Ali, Saeed Soltani und Reza Modarres. „Probabilistic flood inundation mapping of ungauged rivers: Linking GIS techniques and frequency analysis“. Journal of Hydrology 458-459 (August 2012): 68–86. http://dx.doi.org/10.1016/j.jhydrol.2012.06.039.
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Kareem, Kareem Abd Ali, und Hayder A. K. AL-Thamiry. „Identification of Scouring Zones in Ungauged River by Simulation: The Case of Galal Badrah River, Iraq“. Association of Arab Universities Journal of Engineering Sciences 26, Nr. 3 (31.08.2019): 57–67. http://dx.doi.org/10.33261/jaaru.2019.26.3.007.
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Galal Badrah River is one of Iraqi-Iranian border crossing rivers. This river is usually seasonally flooded during any time started from January to May. Its maximum discharge is 2200 m3/s which was recorded during 1985. During floods, banks of this river at many locations need protection against scour problem during floods. A small dam was constructed on this river in 2010 for the purposes of flood control and storage of water. The weir of the dam has a design discharge of 1250 m3/s. Sediments started to accumulate in the reservoir of the dam that reduce its design capacity to 10% during 2017. The flow of Galal Badrah River was simulated by using HEC-RAS 5.0.3 models. were used to simulate by using. Two hydrographs were used at upstream side of the river, one with a maximum discharge of 1250 m3/s and the other is of 2200 m3/s. A normal flow depth is used as a downstream boundary condition. Results of the simulation showed that the velocities to be higher than allowable velocity of scouring. The protection of Galal Badrah river by stack boulders is suggested to be used to avoid the scour at the river bank. The protection will increase Manning’s roughness coefficient from 0.028 to 0.10. The percentage of reduction in velocities after the river protection for the discharges of 1250 and 2200 m3/s were found to be 65.23% and 60.55%, respectively. The reduction in velocity caused increase in the river water levels. As a result, a flood embankment is required to be constructed on the right bank of the river with a height ranges from 2.5 to 5.6 m depending on the water depth at river cross section.
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Hasholt, Bent, Nelly Bobrovitskaya, Jim Bogen, James McNamara, Sebastian H. Mernild, David Milburn und Desmond E. Walling. „Sediment transport to the Arctic Ocean and adjoining cold oceans*“. Hydrology Research 37, Nr. 4-5 (01.08.2006): 413–32. http://dx.doi.org/10.2166/nh.2006.023.
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This paper reviews and synthesises available information on sediment transport to the Arctic Ocean and adjoining seas with open contact to the Atlantic and Pacific Oceans. Special emphasis is placed on calculation and estimation of the sediment flux from the mostly ungauged high Arctic areas on the American continent, in Greenland, and on islands in the Arctic Ocean, and from Russia. In the absence of reliable information on bedload fluxes for most rivers, attention is directed primarily to suspended sediment loads. By combining available monitoring data and estimates for ungauged areas, the total sediment transport to the Arctic Ocean is estimated to be 324–884 × 106 t yr−1. Of this total, a maximum of about 56% can be considered as monitored, while the rest is based on different types of estimate. It is clearly demonstrated that the monitoring network in the high Arctic is inadequate and that there is a lack of knowledge concerning the proportion of the load that actually reaches the sea, as well as bedload.
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Jia, Yao, Huimin Lei, Hanbo Yang und Qingfang Hu. „Terrestrial Water Storage Change Retrieved by GRACE and Its Implication in the Tibetan Plateau: Estimating Areal Precipitation in Ungauged Region“. Remote Sensing 12, Nr. 19 (24.09.2020): 3129. http://dx.doi.org/10.3390/rs12193129.
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The Tibetan Plateau (TP) is referred to as the water tower of Asia, where water storage and precipitation have huge impacts on most major Asian rivers. Based on gravity recovery and climate experiment data, this study analyzed the terrestrial water storage (TWS) changes and estimated areal precipitation based on the water balance equation in four different basins, namely, the upper Yellow River (UYE), the upper Yangtze River (UYA), the Yarlung Zangbo River (YZ), and the Qiangtang Plateau (QT). The results show that the TWS change exhibits different patterns in the four basins and varies from −13 to 2 mm/year from 2003 to 2017. The estimated mean annual precipitation was 260 ± 19 mm/year (QT), 697 ± 26 mm/year (UYA), 541 ± 36 mm/year (UYE), and 1160 ± 39 mm/year (YZ) which performed better than other precipitation products in the TP. It indicates a potential method for estimating basin-scale precipitation through integrating basin average precipitation from the water balance equation in the poorly gauged and ungauged regions.
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Ferrari, Alessia, Marco D'Oria, Renato Vacondio, Paolo Mignosa und Maria Giovanna Tanda. „Hydrograph estimation at upstream ungauged sections on the Secchia River (Italy) by means of a parallel Bayesian inverse methodology“. E3S Web of Conferences 40 (2018): 06034. http://dx.doi.org/10.1051/e3sconf/20184006034.
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In this work, we present a reverse flow routing procedure, which allows estimating discharge hydrographs at upstream ungauged stations by means of information available at downstream monitored sites. The reverse routing problem is solved adopting a Bayesian Geostatistical Approach (BGA). In order to capture the complex hydrodynamic field typical of many real cases of rivers including large floodable areas, meanwhile overcoming the computational time limitations, we adopted as forward model a selfdeveloped 2D-SWE parallel numerical model (PARFLOOD) that allows achieving ratio of physical to computational time of about 500-1000. To exploit the computational capabilities of modern GPU cluster, a parallel procedure to estimate the Jacobian matrix required by the BGA approach has been implemented. The inflow hydrograph in a river reach with several meanders and floodplains has been estimated in “only” 13 hours using a HPC cluster with 10 P100 Nvidia GPUs.
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Nag und Biswal. „Can a Calibration-Free Dynamic Rainfall‒Runoff Model Predict FDCs in Data-Scarce Regions? Comparing the IDW Model with the Dynamic Budyko Model in South India“. Hydrology 6, Nr. 2 (22.04.2019): 32. http://dx.doi.org/10.3390/hydrology6020032.
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Construction of flow duration curves (FDCs) is a challenge for hydrologists as most streams and rivers worldwide are ungauged. Regionalization methods are commonly followed to solve the problem of discharge data scarcity by transforming hydrological information from gauged basins to ungauged basins. As a consequence, regionalization-based FDC predictions are not very reliable where discharge data are scarce quantitatively and/or qualitatively. In such a scenario, it is perhaps more meaningful to use a calibration-free rainfall‒runoff model that can exploit easily available meteorological information to predict FDCs in ungauged basins. This hypothesis is tested in this study by comparing a well-known regionalization-based model, the inverse distance weighting (IDW) model, with the recently proposed calibration-free dynamic Budyko model (DB) in a region where discharge observations are not only insufficient quantitatively but also show apparent signs of observational errors. The DB model markedly outperformed the IDW model in the study region. Furthermore, the IDW model’s performance sharply declined when we randomly removed discharge gauging stations to test the model in a variety of data availability scenarios. The analysis here also throws some light on how errors in observational datasets and drainage area influence model performance and thus provides a better picture of the relative strengths of the two models. Overall, the results of this study support the notion that a calibration-free rainfall‒runoff model can be chosen to predict FDCs in discharge data-scarce regions. On a philosophical note, our study highlights the importance of process understanding for the development of meaningful hydrological models.
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Eng, K., D. M. Carlisle, D. M. Wolock und J. A. Falcone. „PREDICTING THE LIKELIHOOD OF ALTERED STREAMFLOWS AT UNGAUGED RIVERS ACROSS THE CONTERMINOUS UNITED STATES“. River Research and Applications 29, Nr. 6 (09.03.2012): 781–91. http://dx.doi.org/10.1002/rra.2565.
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Bragg, O. M., A. R. Black, R. W. Duck und J. S. Rowan. „Approaching the physical-biological interface in rivers: a review of methods for ecological evaluation of flow regimes“. Progress in Physical Geography: Earth and Environment 29, Nr. 4 (Dezember 2005): 506–31. http://dx.doi.org/10.1191/0309133305pp460ra.
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New European legislation known as the Water Framework Directive (WFD) challenges catchment hydrologists and freshwater biologists to quantify the risk of damage to the organic communities of rivers that arises from anthropogenic distortion of the natural flow regime. Here, we take the first step towards this goal by collecting together relevant information from the two disciplines. An extensive biological literature is examined for insights into the ways in which the species and communities associated with rivers might change when the flow regime is altered. From the hydrological literature, the indicators of flow regime and flow regime change that are pertinent to ecology are described, and consideration is given to means of deriving flow regime data for ungauged river reaches. Attempts to combine hydrology and ecology in classifying rivers and in setting flow objectives to favour biota are then reviewed, together with integrated approaches to river management that aim to promote ecological quality. A significant scale disparity is noted between the disciplines, hydrology being studied at catchment, subcatchment and reach scales, and biology generally at local level. Nonetheless, both yield methods with potential applications in aspects of WFD implementation. The approach with most appeal for general risk assessment is based on the concept of hydrological alteration. This technique employs flow regime variables selected for their importance to aquatic and riparian ecology, and quantifies deviations from the natural values of these variables at reach scale. For WFD purposes, calibration of the scale of hydrological alteration in terms of risk to ecological status is desirable. In this, priority should be given to identification of the level of hydrological alteration that corresponds to the division between good and moderate ecological status.
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Grandry, M., S. Gailliez, C. Sohier, A. Verstraete und A. Degré. „A method for low flow estimation at ungauged sites, case study in Wallonia (Belgium)“. Hydrology and Earth System Sciences Discussions 9, Nr. 10 (11.10.2012): 11583–614. http://dx.doi.org/10.5194/hessd-9-11583-2012.
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Abstract. Being able to estimate low flows at any point of a river is really important nowadays for a good integrated management of rivers. Knowing the magnitude as well as the frequency of such extreme events becomes essential. In order to build a model of low flow calculation, usable in ungauged catchments and which takes also into account low flow frequency, we started with a low flow frequency analysis including a comparison of different distributions. Two-parameter Lognormal and Gamma were the most common distributions that fit low flow data in Wallonia. This was followed by a regionalisation of low flows using 25 different climatic and physical catchment variables, and the development of regression models that can be used to estimate the minimum 7-day average flow for different return periods, using catchment characteristics. The variables the most correlated to specific minimum 7-day average flows were the recession coefficient and percolation, regardless of the return period. The determination coefficients of the models ranged from 0.51 to 0.67 for calibration and from 0.61 to 0.80 for validation. Finally, regression coefficients were logarithmically linked to the return period. This enabled us to develop a single model per region and for the whole study area, in function of the return period. In conclusion, the method developed in this study allows us to estimate low flows in gauged and ungauged catchments of a given region for a given return period. The interest of regionalisation and development of regional models is also discussed.
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Peña-Arancibia, J. L., A. I. J. M. van Dijk, M. Mulligan und L. A. Bruijnzeel. „The role of climatic and terrain attributes in estimating baseflow recession in tropical catchments“. Hydrology and Earth System Sciences 14, Nr. 11 (04.11.2010): 2193–205. http://dx.doi.org/10.5194/hess-14-2193-2010.
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Abstract. The understanding of low flows in rivers is paramount more than ever as demand for water increases on a global scale. At the same time, limited streamflow data to investigate this phenomenon, particularly in the tropics, makes the provision of accurate estimations in ungauged areas an ongoing research need. This paper analysed the potential of climatic and terrain attributes of 167 tropical and sub-tropical unregulated catchments to predict baseflow recession rates. Daily streamflow data (m3 s–1) from the Global River Discharge Center (GRDC) and a linear reservoir model were used to obtain baseflow recession coefficients (kbf) for these catchments. Climatic attributes included annual and seasonal indicators of rainfall and potential evapotranspiration. Terrain attributes included indicators of catchment shape, morphology, land cover, soils and geology. Stepwise regression was used to identify the best predictors for baseflow recession coefficients. Mean annual rainfall (MAR) and aridity index (AI) were found to explain 49% of the spatial variation of kbf. The rest of climatic indices and the terrain indices average catchment slope (SLO) and tree cover were also good predictors, but co-correlated with MAR. Catchment elongation (CE), a measure of catchment shape, was also found to be statistically significant, although weakly correlated. An analysis of clusters of catchments of smaller size, showed that in these areas, presumably with some similarity of soils and geology due to proximity, residuals of the regression could be explained by SLO and CE. The approach used provides a potential alternative for kbf parameterisation in ungauged catchments.
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Rianna, M., F. Russo und F. Napolitano. „Stochastic index model for intermittent regimes: from preliminary analysis to regionalisation“. Natural Hazards and Earth System Sciences 11, Nr. 4 (27.04.2011): 1189–203. http://dx.doi.org/10.5194/nhess-11-1189-2011.
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Abstract. In small and medium-sized basins or in rivers characterized by intermittent discharges, with low or negligible/null observed values for long periods of the year, the correct representation of the discharge regime is important for issues related to water management and to define the amount and quality of water available for irrigation, domestic and recreational uses. In these cases, only one index as a statistical metric is often not enough; it is thus necessary to introduce Flow Duration Curves (FDC). The aim of this study is therefore to combine a stochastic index flow model capable of reproducing the FDC record period of a river, regardless of the persistence and seasonality of the series, with the theory of total probability in order to calculate how often a river is dry. The paper draws from preliminary analyses, including a study to estimate the correlation between discharge indicators Q95, Q50 and Q1 (discharges exceeding 95%, 50% or 1% of the time, respectively) and some fundamental characteristics of the basin, as well as to identify homogeneous regions in the target area through the study of several geo-morphological features and climatic conditions. The stochastic model was then applied in one of the homogeneous regions that includes intermittent rivers. Finally, the model was regionalized by means of regression analysis in order to calculate the FDC for ungauged basins; the reliability of this method was tested using jack-knife validation.
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Zlatanović, Nikola, und Sonja Gavrić. „Comparison of an Automated and Manual Method for Calculating Storm Runoff Response in Ungauged Catchments in Serbia“. Journal of Hydrology and Hydromechanics 61, Nr. 3 (01.09.2013): 195–201. http://dx.doi.org/10.2478/johh-2013-0025.
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Abstract Estimation of discharge from ungauged catchments based on rainfall-runoff analysis is a very frequent task in engineering hydrology. Very often, design discharges are needed for streams or small rivers where no streamflow data is available (river training works, culverts, small hydropower plants, etc). This study uses a well established lumped hydrologic rainfall-runoff model to compare two different approaches in data preparation. The traditional method of manual obtainment of catchment parameters was compared to a more contemporary methodology using automation with geographic information systems, digital terrain models and available datasets, with an emphasis on open-source tools and freely available datasets. Both techniques were implemented on more than 100 catchments in Serbia to calculate storm runoff response. The results show minor differences that are insignificant compared to the time and resources saved with the automated techniques. The use of such automated methods enables the hydrologist to direct more attention to other factors that influence discharge even more than catchment parameters, such as rainfall, soil and land use data.
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Paiva, R. C. D., W. Collischonn, M. P. Bonnet, L. G. G. de Gonçalves, S. Calmant, A. Getirana und J. Santos da Silva. „Assimilating in situ and radar altimetry data into a large-scale hydrologic-hydrodynamic model for streamflow forecast in the Amazon“. Hydrology and Earth System Sciences Discussions 10, Nr. 3 (07.03.2013): 2879–925. http://dx.doi.org/10.5194/hessd-10-2879-2013.
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Abstract. In this work we introduce and evaluate a data assimilation framework for gauged and radar altimetry-based discharge and water levels applied to a large scale hydrologic-hydrodynamic model for stream flow forecasts over the Amazon River basin. We used the process-based hydrological model called MGB-IPH coupled with a river hydrodynamic module using a storage model for floodplains. The Ensemble Kalman Filter technique was used to assimilate information from hundreds of gauging and altimetry stations based on ENVISAT satellite data. Model state variables errors were generated by corrupting precipitation forcing, considering log-normally distributed, time and spatially correlated errors. The EnKF performed well when assimilating in situ discharge, by improving model estimates at the assimilation sites and also transferring information to ungauged rivers reaches. Altimetry data assimilation improves results at a daily basis in terms of water levels and discharges with minor degree, even though radar altimetry data has a low temporal resolution. Sensitivity tests highlighted the importance of the magnitude of the precipitation errors and that of their spatial correlation, while temporal correlation showed to be dispensable. The deterioration of model performance at some unmonitored reaches indicates the need for proper characterization of model errors and spatial localization techniques for hydrological applications. Finally, we evaluated stream flow forecasts for the Amazon basin based on initial conditions produced by the data assimilation scheme and using the ensemble stream flow prediction approach where the model is forced by past meteorological forcings. The resulting forecasts agreed well with the observations and maintained meaningful skill at large rivers even for long lead times, e.g. > 90 days at the Solimões/Amazon main stem. Results encourage the potential of hydrological forecasts at large rivers and/or poorly monitored regions by combining models and remote sensing information.
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Annis, Antonio, Fernando Nardi, Andrea Petroselli, Ciro Apollonio, Ettore Arcangeletti, Flavia Tauro, Claudio Belli, Roberto Bianconi und Salvatore Grimaldi. „UAV-DEMs for Small-Scale Flood Hazard Mapping“. Water 12, Nr. 6 (16.06.2020): 1717. http://dx.doi.org/10.3390/w12061717.
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Devastating floods are observed every year globally from upstream mountainous to coastal regions. Increasing flood frequency and impacts affect both major rivers and their tributaries. Nonetheless, at the small-scale, the lack of distributed topographic and hydrologic data determines tributaries to be often missing in inundation modeling and mapping studies. Advances in Unmanned Aerial Vehicle (UAV) technologies and Digital Elevation Models (DEM)-based hydrologic modeling can address this crucial knowledge gap. UAVs provide very high resolution and accurate DEMs with low surveying cost and time, as compared to DEMs obtained by Light Detection and Ranging (LiDAR), satellite, or GPS field campaigns. In this work, we selected a LiDAR DEM as a benchmark for comparing the performances of a UAV and a nation-scale high-resolution DEM (TINITALY) in representing floodplain topography for flood simulations. The different DEMs were processed to provide inputs to a hydrologic-hydraulic modeling chain, including the DEM-based EBA4SUB (Event-Based Approach for Small and Ungauged Basins) hydrologic modeling framework for design hydrograph estimation in ungauged basins; the 2D hydraulic model FLO-2D for flood wave routing and hazard mapping. The results of this research provided quantitative analyses, demonstrating the consistent performances of the UAV-derived DEM in supporting affordable distributed flood extension and depth simulations.
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K.C., Prakash, Suresh Baral, Binaya Kumar Mishra und Indra Prasad Timilsina. „Experimental and Numerical Simulations of Sediment in Fusre River Basin, Nepal“. Himalayan Journal of Applied Science and Engineering 3, Nr. 1 (30.06.2022): 39–52. http://dx.doi.org/10.3126/hijase.v3i1.48254.
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This study presents about the analysis of sediment generation of the ungauged basin Fusre basin by modeling and also with the help of rainfall simulator. Many rivers in Nepal are either ungauged or poorly gauged due to extreme complex terrains, monsoon climate and lack of technical and financial supports. The Soil and Water Assessment Tool (SWAT) was applied for watershed delineation of the Fusre basin and the basin delineated into seven sub-basin that generate the river network, which also provides the information like stream link, stream order, stream length, slope etc. The calibration was performed using data from 2003 to 2010 and validation for the period from 2011 to 2015 at a daily time step. The model performance was evaluated based on computed statistical parameters. For the calibration period of the discharge and sediment flow, the performance of the model was very good, with a coefficient of determination R2= 0.9528, Nash-Sutcliffe Efficiency NSE = 0.942, RMSE = 0.24, and Percent Bias= 14.78, Similarly, the continuous model performance for the validation period was good, with R2 = 0.8655, NSE = 0.925, RMSE = 0.275 and Percent Bias = 18.03. Also a series of laboratory experiments was also carried out by changing the land use, soil parameter, and rainfall intensity by varying depth of soil sample and slope for comparative study with model but just for performance of apparatus. The performance of rainfall simulator was good. From the experimental method the calculation value of coefficient of determination R2 is equal to 0.67, NSE value is equal to 0.865 and PBIAS was equal to 30. The performance of both experimental and simulated data was satisfactory.
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Ferrari, Alessia, Marco D'Oria, Renato Vacondio, Alessandro Dal Palù, Paolo Mignosa und Maria Giovanna Tanda. „Discharge hydrograph estimation at upstream-ungauged sections by coupling a Bayesian methodology and a 2-D GPU shallow water model“. Hydrology and Earth System Sciences 22, Nr. 10 (16.10.2018): 5299–316. http://dx.doi.org/10.5194/hess-22-5299-2018.
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Abstract. This paper presents a novel methodology for estimating the unknown discharge hydrograph at the entrance of a river reach when no information is available. The methodology couples an optimization procedure based on the Bayesian geostatistical approach (BGA) with a forward self-developed 2-D hydraulic model. In order to accurately describe the flow propagation in real rivers characterized by large floodable areas, the forward model solves the 2-D shallow water equations (SWEs) by means of a finite volume explicit shock-capturing algorithm. The two-dimensional SWE code exploits the computational power of graphics processing units (GPUs), achieving a ratio of physical to computational time of up to 1000. With the aim of enhancing the computational efficiency of the inverse estimation, the Bayesian technique is parallelized, developing a procedure based on the Secure Shell (SSH) protocol that allows one to take advantage of remote high-performance computing clusters (including those available on the Cloud) equipped with GPUs. The capability of the methodology is assessed by estimating irregular and synthetic inflow hydrographs in real river reaches, also taking into account the presence of downstream corrupted observations. Finally, the procedure is applied to reconstruct a real flood wave in a river reach located in northern Italy.
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Hulley, Mike, Colin Clarke und Ed Watt. „Occurrence and magnitude of low flows for Canadian rivers: an ecozone approach“. Canadian Journal of Civil Engineering 41, Nr. 1 (Januar 2014): 1–8. http://dx.doi.org/10.1139/cjce-2013-0300.
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Low-flow occurrence and magnitude have been documented for Canada using the National Ecological Framework. The low flow database is composed of the 7-day low flow with 2-year return period (7Q2) values for 453 natural flow hydrometric stations with record lengths of at least 30 years; drainage areas ranged from 10 to 30 000 km2. Occurrence zones corresponding to predominant season for annual low flows are associated with ecozones. The ecozone scale was found to be suitable for regional analysis for several ecozones. For some ecozones there were insufficient data for regional analysis and for others finer resolution is required. Regional regression equations were developed for estimating 7Q2 in terms of area for ecozones containing at least 20 stations. The results of this work will help practitioners to identify the season of low flow occurrence and the appropriate method of analysis, and provide a means of estimating 7Q2 for ungauged sites for some ecozones.
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Gao, Zhen, Guoqiang Tang, Wenlong Jing, Zhiwei Hou, Ji Yang und Jia Sun. „Evaluation of Multiple Satellite, Reanalysis, and Merged Precipitation Products for Hydrological Modeling in the Data-Scarce Tributaries of the Pearl River Basin, China“. Remote Sensing 15, Nr. 22 (13.11.2023): 5349. http://dx.doi.org/10.3390/rs15225349.
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Satellite and reanalysis precipitation estimates of high quality are widely used for hydrological modeling, especially in ungauged or data-scarce regions. To improve flood simulations by merging different precipitation inputs or directly merging streamflow outputs, this study comprehensively evaluates the accuracy and hydrological utility of nine corrected and uncorrected precipitation products (TMPA-3B42V7, TMPA-3B42RT, IMERG-cal, IMERG-uncal, ERA5, ERA-Interim, GSMaP, GSMaP-RNL, and PERSIANN-CCS) from 2006 to 2018 on a daily timescale using the Coupled Routing and Excess Storage (CREST) hydrological model in two flood-prone tributaries, the Beijiang and Dongjiang Rivers, of the Pearl River Basin, China. The results indicate that (1) all the corrected precipitation products had better performance (higher CC, CSI, KGE’, and NSCE values) than the uncorrected ones, particularly in the Beijiang River, which has a larger drainage area; (2) after re-calibration under Scenario II, the two daily merged precipitation products (NSCE values: 0.73–0.87 and 0.69–0.82 over the Beijiang and Dongjiang Rivers, respectively) outperformed their original members for hydrological modeling in terms of BIAS and RMSE values; (3) in Scenario III, four evaluation metrics illustrated that merging multi-source streamflow simulations achieved better performance in streamflow simulation than merging multi-source precipitation products; and (4) under increasing flood levels, almost all the performances of streamflow simulations were reduced, and the two merging schemes had a similar performance. These findings will provide valuable information for improving flood simulations and will also be useful for further hydrometeorological applications of remote sensing data.
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Quintero, Felipe, Witold F. Krajewski und Marcela Rojas. „A Flood Potential Index for Effective Communication of Streamflow Forecasts at Ungauged Communities“. Journal of Hydrometeorology 21, Nr. 4 (April 2020): 807–14. http://dx.doi.org/10.1175/jhm-d-19-0212.1.
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AbstractThis study proposes a flood potential index suitable for use in streamflow forecasting at any location in a drainage network. We obtained the index by comparing the discharge magnitude derived from a hydrologic model and the expected mean annual peak flow at the spatial scale of the basin. We use the term “flood potential” to indicate that uncertainty is associated with this information. The index helps communicate flood potential alerts to communities near rivers where there are no quantitative records of historical floods to provide a reference. This method establishes a reference that we can compare to forecasted hydrographs and that facilitates communication of their relative importance. As a proof of concept, the authors present an assessment of the index as applied to the peak flows that caused severe floods in Iowa in June 2008. The Iowa Flood Center uses the proposed approach operationally as part of its real-time hydrologic forecasting system.
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Benito, G., B. A. Botero, V. R. Thorndycraft, M. Rico, Y. Sánchez-Moya, A. Sopeña, M. J. Machado und O. Dahan. „Rainfall-runoff modelling and palaeoflood hydrology applied to reconstruct centennial scale records of flooding and aquifer recharge in ungauged ephemeral rivers“. Hydrology and Earth System Sciences Discussions 7, Nr. 6 (21.12.2010): 9631–60. http://dx.doi.org/10.5194/hessd-7-9631-2010.
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Abstract. In this study we propose a multi-source data approach for quantifying long-term flooding and aquifer recharge in ungauged ephemeral rivers. The methodology is applied to the Buffels River, at 9000 km2 the largest ephemeral river in Namaqualand (NW South Africa), a region with scarce stream flow records limiting research investigating hydrological response to global change. Daily discharge and annual flood series (1965–2006) were estimated from a distributed rainfall-runoff hydrological model (TETIS) using rainfall gauge records located within the catchment. The model was calibrated and validated with data collected during a two year monitoring programme (2005–2006) at two stream flow stations, one each in the upper and lower reaches of the catchment. In addition to the modelled flow records, non-systematic flood data were reconstructed using both sedimentary and documentary evidence. The palaeoflood record identified at least 25 large floods during the last 700 yr; with the largest events reaching a minimum discharge of 255 m3 s−1 (450 yr return period) in the upper basin, and 510 m3 s−1 (100 yr return period) in the lower catchment. Since 1925 AD, the flood hydrology of the Buffels River has been characterised by a decrease in the magnitude and frequency of extreme events, with palaeoflood discharges five times greater than the largest modelled floods during the period 1965–2006. Large floods generated the highest hydrograph volumes, however their contribution to aquifer recharge is limited as this depends on other factors such as flood duration and storage capacity of the unsaturated zone prior to the flood. Floods reaching flows associated with 5–10 yr return periods (120–140 m3 s−1) and flowing for 12 days are able to fully saturate the Spektakel aquifer in the lower Buffels River basin.