International Journal of Hydrology Science and Technology (9 papers in press)

Regular Issues

• The applicability of the formulas developed on the Manning-Strickler and Keulegan equations for the calculation of flow resistance for shallow flow in gravel-bed streams - a case study  
  by Bogusław Michalec 
  Abstract: The results of field measurements in reaches with determined measuring cross-sections of four streams was used to test the applicability of conventional flow resistance equations with dimensionless variables in the form of d/D, R/D or dmax/ and R/. Among the 27 assessed formulas developed on the model of the Manning-Strickler and Keulegan equations, only the power equations of Griffiths and Charlton et al. gave satisfactory results. The applied VPE equation, developed by Ferguson, allows to obtain the estimated value of the coefficient of resistance. As a result, empirical formulas were developed as correlations of (8/f)1/2 with dimensionless parameters. Only correlation for the maximum depth (dmax) obtained higher values of the coefficient of determination. The proposed adoption of the standard deviation of the size distribution curve in dimensionless parameters in the form of dmax/ and R/, may provide a practical approach in determining the resistance coefficient.
  Keywords: resistance coefficient; roughness coefficient; sediment grain diameter; hydraulic diameter; gravel bed.
  DOI: 10.1504/IJHST.2025.10074321
   
  
• Hydrological processes of environmental isotopes in Karamana River Basin, Kerala, India: a case study of isotopic hydrology  
  by Ravi Ande, Aaron Anil Chadee, Madhuri Nigam, Darshan Mehta, Hazi Azamathulla 
  Abstract: Hydrological modelling of water resources requires a clear understanding of surface water-groundwater interactions in river basins. The Karamana River Basin, a vital source for Thiruvananthapuram city, presently lacks effective isotope-based assessments and management strategies. Environmental isotope analysis revealed that monsoon precipitation exhibited enriched δ18O values (-2.01, -2.57, -1.53%) compared to river and groundwater, indicating the significant role of rainfall in streamflow generation. Seasonal hydrochemical variations were also evident. During the non-monsoon period, cation concentrations followed Ca2+ > Na+ > Mg2+ > K+ > Fe, while anions were dominated by HCO3- > Cl- > SO42- > NO3-. In the monsoon season, the order remained similar but with reduced concentrations. Groundwater δ18O values were more depleted than those of rainfall and river water (HL = -3.12%; ML = -4.2%; LL = -2.85%), highlighting recharge contributions and seasonal variability. These findings emphasise the importance of isotope-based monitoring for sustainable basin management.
  Keywords: Karamana River Basin; hydrological modelling; stable isotope; water assessment tool; temporal variation; India.
  DOI: 10.1504/IJHST.2025.10074375
   
  
• Research on factors influencing conductivity in river water sampling contaminated by heavy metals  
  by Yan Wu, Yi Zhang, Yuanbo Wang 
  Abstract: The river water conductivity is significantly affected when contaminated by heavy metals. Experimental studies were conducted using silty clay to investigate the factors influencing water conductivity. The variations in conductivity were observed under the influence of factors such as HA content, temperature, and centrifugal filtration. Adding HA to the clay resulted in a significant increase in water conductivity. The water conductivity after centrifugal filtration was higher than before centrifugal filtration. When the concentration of CuSO4 was below 200 mg/L, the conductivity at 10 C was higher than the conductivity at 20 C. When the CuSO4 concentration was above 200 mg/L, the opposite result was observed. The correlation between the factors that significantly affected the water conductivity could be ranked as follows: CuSO4 concentration > centrifugal filtration > HA concentration. Converting unfiltered water conductivity to ion concentration results in a 10% reduction.
  Keywords: humic acid; temperature; centrifugal filtration; conductivity.
  DOI: 10.1504/IJHST.2025.10074497
   
  
• Performance evaluation of water supply distribution in Kombolcha Town using hydraulic modelling in WaterGEMS  
  by Dagmawie Negash Agonafire, Bezawit Tesfaye Ejigu, Asalf Shumete Eshete, Girum Metaferia Afessa 
  Abstract: Ethiopias water utilities, including Kombolcha, face challenges from rising demand, increased consumption, and aging distribution networks. This study evaluates the hydraulic performance of Kombolcha water distribution system, focusing on issues like intermittent supply, low pressure, insufficient velocity, and limited coverage. Using WaterGEMS modelling, key hydraulic parameters of pressure and velocity were analysed during minimum and peak demand periods. Results show over 70% of pressure nodes fall below acceptable levels during peak hours, while only 29% of pipes maintain optimal velocity (0.6-2 m/s) limiting water supply. High velocities exceeding 3 m/s in 12% of pipes during peak demand exacerbate water loss and inefficiency. The system faces a supply gap of 3,536 m3/day and achieving only 75% coverage. Recommendations include adding new water sources, upgrading infrastructure, balancing pressure with valves, and replacing aging pipes. These measures aim to improve performance, reduce water loss, and enhance resilience to growing urban and industrial demands.
  Keywords: hydraulic performance; water supply distribution; water supply coverage; WaterGEMS modelling; Kombolcha; pressure; velocity.
  DOI: 10.1504/IJHST.2026.10075573
   
  
• A measured bias correction model for the estimation of river contaminant loads from discharge data  
  by Ababu T. Tiruneh, Alfred F. Murye 
  Abstract: Estimation of contaminant loads carried by rivers is important for water quality management. A study was carried out for estimating mean monthly solids load from river discharge data by application of the rating curve equation and method of moments. The results show both the untransformed and log transformed discharge data underestimate the solids load with relative standard deviation of residuals of 60% for untransformed discharge data and 55.6% for log-transformed discharge data. Application of measured load bias correction modelling reduced the relative standard deviation of residuals to 10.8% for the untransformed discharge data and 9% for the log transformed discharge data. The measured solids load bias was reduced from 1.6 to around 1.0 on average. The residuals may be reduced further by using mean discharge derived from data through optimisation. The method has limitation where there is weak relationship between contaminant load and river discharge where further research is needed.
  Keywords: contaminant load; river discharge; solids load; method of moments; rating curve.
  DOI: 10.1504/IJHST.2026.10075699
   
  
• Impact of climate change on soil loss in small catchments in the Amazon and Cerrado biomes  
  by Ruan Veloso Sousa Sobral, Ana Karla Rodrigues Lobato, Amanda De Cássia Lobato Soares Lobato Soares, Leonardo Melo De Mendonça, Josias Da Silva Cruz, Claudio Blanco 
  Abstract: Soil loss was estimate in two small catchments, using observed and future rainfall data simulated by NASA Exchange Global Daily Downscaled Projections (NEX-GDDP) climate models, based on the Coupled Model Intercomparison Project Phase 6 (CMIP6). Soil loss was determined for the SSP2-4.5 (Shared Socioeconomic Pathways) and SSP5-8.5 scenarios. In the Igarape da Prata small catchment (Amazon), the soil loss for the SSP2-4.5 increased by 3.8% (2025-2050), 2.8% (2051-2075) and 1.9% (2076-2099). In the case of SSP5-8.5, soil loss in the period 20252050 was approximately 0, while in the subsequent periods there was a reduction of 8% and 7.5%. In the Piranhas River catchment (Cerrado), soil loss reduced in both scenarios and in the same periods. Therefore, in the Amazon small catchment, land use management strategies are necessary and in the Cerrado small catchment, current agricultural management must be maintained to avoid an increase in soil loss in the future.
  Keywords: USLE; NEX-GDDP; CMIP6; erosivity.
  DOI: 10.1504/IJHST.2026.10076048
   
  
• Bathymetry contribution to the estimation of storage capacity and silting of dam reservoirs. Case study of Beni Haroun dam, North-East Algeria  
  by Guendouz Seyyid Ali, Chebbah Lynda 
  Abstract: This study assesses sedimentation in Algerias Beni Haroun dam reservoir, a vital water source for 5 million people irrigating 42,000 hectares. Using comparative DEM analysis from 2000 and 2013, researchers quantified sediment accumulation during the first operational decade (2003-2013). Results revealed substantial sediment accumulation of 107.78 hm3, exceeding projected rates (60 hm3 per decade) by 20%. This unexpected sedimentation caused an 11% reduction in usable storage capacity from the initial 983.33 hm3 capacity. Projections indicate that if current rates persist, the reservoir could reach functional obsolescence by 2035 - within 22 years - of operation drastically shortening its forecasted lifespan. These findings highlight the urgent need to improve sedimentation prediction models and implement adaptive management strategies to preserve long-term water storage capacity for this critical resource serving five Wilayas. The bathymetric data from ANBT proved essential for this capacity assessment and future planning.
  Keywords: Siltation; Beni Haroun dam; Bathymetry; digital elevation models; DEMs; GIS; Algeria.
  DOI: 10.1504/IJHST.2026.10076844
   
  
• Fuse plug operation simulation of a barrage for flood management  
  by Muhammad Arslan Tabassum, Mohammad Usman Ashraf, Mohammad Awais Zafar, Mohammad Masood, Ghullam Nabi, Mohammad Akbar 
  Abstract: Flooding in central Punjab, Pakistan, particularly from the Indus and Chenab Rivers, has caused extensive damages to infrastructure, urban areas and agricultural lands, especially with seven calamitous floods those occurred between 2010 and 2017 in this area. To protect hydraulic structures and manage flood risks, fuse plugs (breaching sections) are used. This study aimed to analyse the effectiveness of fuse plug in right marginal bund of Khanki Barrage on the Chenab River for flood management between Marala and Qadirabad barrages, using the HEC-RAS 2-D model. Different flood scenarios were simulated, including high, very high, and exceptionally high flood events. Results showed that in the extreme flood event of 947,000 cusecs in September 2014, the breaching of the fuse plug affected 386.2 km2 of land, with 9,273 acres of agriculture land and 24,442 residents. The study highlights the effective floodwater passage from fuse plug to downstream, emphasising not only the safety of the structure but also the significant social and economic consequences of extreme flood events in floodplains.
  Keywords: breaching section; floodplain management; HEC-RAS 2D; hydraulic modelling; hydraulic structure.
  DOI: 10.1504/IJHST.2026.10077111
   
  
• Application of the HEC-HMS model for runoff simulation in Al-Sanober Watershed, Syria  
  by Amer Qousai Aldarwish, Ruba Dahham Alsaeed, Mais Mayassah, Shaymaa Alsamia, Edina Koch 
  Abstract: Reliable runoff modeling is essential for water-resource planning in seasonal, ungauged basins. This study developed an HEC-HMS model for the 252 km2 AL-Sanober watershed, using SCS-CN for losses (with GCN250 curve numbers), SCS unit hydrograph for rainfallrunoff transformation, and Muskingum routing for channel flow. Curve numbers were adjusted for slope with Hangs equation (2006) and an initial abstraction ratio = 0.05. The model was calibrated and validated with two observed storm events and evaluated using RSR, NSE, PBIAS, and R2. Slope-adjusted CN inputs produced accurate simulations of runoff volume and peak discharge. A Type II 24-h temporal distribution was confirmed via statistical indicators and trial-and-error for hypothetical design storms, enabling derivation of runoff curves, coefficients, and return-period estimates. Mean annual runoff (2008-2015) was 373 mm, equivalent to ~85 million m3. Sensitivity analysis showed peak discharge responds more strongly to CN changes than to rainfall increases, emphasising watershed-specific CN refinement.
  Keywords: HEC-HMS; GCN250; slope-adjusted CN; initial abstraction ratio; runoff hydrograph.
  DOI: 10.1504/IJHST.2026.10077391