Discharge Estimation with the Use of Unmanned Aerial Vehicles (UAVs) and Hydraulic Methods in Shallow Rivers

Although river discharge is essential hydrologic information, it is often absent, especially for small rivers and remote catchment areas. Practical difficulties frequently impede the installation and operation of gauging stations, while satellite-sensed data have proved to be relatively useful only for discharge estimation of large-scale rivers. In this study, we propose a new methodology based on UAV-sensed data and photogrammetry techniques combined with empirical hydraulic equations for discharge estimation. In addition, two different riverbed particle size distributions were incorporated, to study the effect of fine sediment inclusion (or exclusion) in the estimation process. Accordingly, 17 study sites were selected and six different approaches were applied in each. Results show that at 75% of sites at least one approach produced an accurate discharge estimation, while in 10 out the 17 sites (58.8%) all six approaches produced accurate estimations. A strong correlation between a threshold value for the hydraulic radius (Rh = 0.3 m) of cross-sections and high estimation errors for sites exceeding it was also observed. The fine sediment inclusion improved only the performance of certain approaches and did not have a consistently positive effect. Overall, the relatively high percentage of sites with satisfactory discharge estimates indicates that using UAV-derived data and simple hydraulic equations can be used for this purpose, with an acceptable level of accuracy.

Debit Puncak Harian Tahunan Metode HSS Nakayasu dan Debit Terukur di DAS Muke Kabupaten TTSS SERVICES-CURVE NUMBER DAN DEBIT TERUKUR DI DAERAH ALIRAN SUNGAI MUKE KABUPATEN TIMOR TENGAH SELATAN

The Muke River is prone to flooding. flooding is caused by conversion in land use due to the migrating plantation system. In the Muke river, it is necessary to analyze the discharge estimation to determine the potential of water in the Muke river. In this study, the authors performed peak discharge calculation using measured calculation model and calculate. Measured calculations using discharge’s curve and calculated by using hydrographic method of synthetic unit namely Nakayasu. The results of the analysis for the calculation of discharge on the Muke river using the discharge curve obtained that the peak discharge occurred in 2012 with Qmax = 99.41 m3/s and the smallest discharge occurred in 2010 with Qmin = 13.19 m3/s, the results of the analysis for the calculation of discharge on the Muke river using the Nakayasu method obtained peak discharge occurred in 2010 with Qmax= 184.74 m3/s and the smallest discharge occurred in 2014 with Qmin = 94.33 m3/s.

Prediction of Daily Streamflow Using Various Kernel Function Based Regression: A Case Study in India

River daily discharge estimation and modeling considers an important step for scheduling and planning different water resources for sustainable socio-economic development. In the current work, four techniques of Gaussian processes regression (GPR): Polynomial Kernel, Radial Basis Function Kernel, Normalized Polynomial Kernel, and PUK Kernel, were used to model the daily discharge. Hydrological-datasets containing daily-stage (m) and discharge (m3/sec) were gathered over the period from 2004-2013. The datasets were divided into two sections: (i) models training containing 70% (2004-2010) of the total data and (ii) remaining 30% (2011- 2013) were for testing. Comparing all the four developed models, our findings show that the superlative model was the PUK-Kernel model with a correlation coefficient (r) of 0.96, MAE of 36.70 m3/s, RMSE of 90.92 m3/s, RAE of 17.50 %, RRSE of 26.05 % in the training period. Whereas, it performed equally well in the testing period with r = 0.97, MAE = 44.84 m3/s, RMSE = 95.05 m3/s, RAE = 17.98 %, RRSE = 24.94 % in the testing period. Our findings can be included that GPR-PUK was more accurate and stable than other models, and can be used to help water-users, decision-makers, development-planners for managing water resources and achieving sustainable development.

Riparian vegetation as a marker for bankfull and management discharge evaluation: The case study of Rio Torbido river basin (central Italy)

Bankfull discharge estimation is a crucial step in river basin management. Such evaluation can be carried out using hydrological and hydraulic modelling to estimate flow-depths, flow velocities and flood prone areas related to a specific return period. However, different methodological approaches are described in the scientific literature. Such approaches are typically based either on the assumption that the bankfull discharge corresponds to a narrow range of return periods, or on the correlation to the river geomorphological or local descriptors, such as vegetation. In this study, we used high-resolution topographic data and a combined hydrological-hydraulic modelling approach in order to estimate bankfull discharge in the ungauged basin of Rio Torbido River (Central Italy). The field survey of plant species made it possible to investigate the link between the riparian areas and the bankfull discharge. Our results were in line with previous studies and showed a promising agreement between the results of the hydraulic modelling and the plant species present in the investigated river cross sections. The plant species position could be indeed used for a preliminary delineation of the riparian areas to be verified more deeply with the hydrological-hydraulic approach.

DOPPLER NON-CONTACT RADAR SENSORS FOR WATER DISCHARGE ESTIMATION: ADVANTAGES AND LIMITATIONS

The use of non-contact doppler flow radars to determine water discharge is a widespread trend in hydrometeorological surveying and monitoring. However, is it reasonable to consider such an instrument as one of the most suitable and perspective for the hydrological observation network? In-situ testing have been carrying out by authors of this article and the analysis performed in scientific papers cannot provide a single-valued positive conclusion on this issue. Obvious advantage of these radars as independent safe mode of operation seems to overweight their obvious weak points. Many "undercurrents" do not allow this method to be recognized as reliable, such as the problem of transition from surface to medium flow velocities, which consists in the data processing apparatus, reliable positioning of the device, blanking distance task and etc. All in all, this article discusses the main advantages and "vulnerabilities" of the use of such an instrument as non-contact doppler radars to determine water discharge from a scientific and practical points of view.