International Journal of Hydrology Science and Technology (8 papers in press)

Regular Issues

• 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
   
  
• 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
   
  
• Hydrological vulnerabilities of Himalayas: implications of climate change  
  by Humaira Gulshan, Nasir Ahmad Rather, Pervez Alam 
  Abstract: The Himalayan region, known for its natural variety and significance is increasingly being exposed to the effects of climate change. Himalayas encompass twelve major river basins which provide a key source of freshwater for millions of people in the South and Central Asia. The Indus River system is particularly important, as it is strongly reliant on glacial and snowmelt runoff to maintain its flow. However, rapid climatic changes are putting tremendous strain on this fragile hydrological balance. This review synthesises existing research on the implications of climate change for water availability in the Himalayan region. It explores key hydrological variables, such as glacier retreat, altered precipitation patterns, declining stream flows, and evapotranspiration dynamics; highlighting the increased frequency and severity of climate-related hazards such as droughts, famines, and glacial lake outburst floods (GLOFs). The study highlights a steady trend of diminishing water security in the region, fuelled by both climatic and anthropogenic pressures. The review provides a critical assessment of previous and present hydrological conditions and lays the groundwork for evidence-based policy solutions. The present work intends to help develop long-term water resource management strategies that are adapted to the Himalayan landscapes vulnerabilities.
  Keywords: climate change; temperature; precipitation; Himalayas; hydrological cycle; streamflow; glaciers; land use change; global warming.
  DOI: 10.1504/IJHST.2026.10078225
   
  
• Enhanced energy dissipation in modified stepped weirs: a hydrodynamic investigation  
  by Ghufran Faris Alrahhawi, Ahmed Abdulhameed Ahmed Alkattan, Ahmed Y. Mohammed 
  Abstract: Energy dissipation is vital for safeguarding stepped weirs and reducing stilling basin costs. Moving beyond traditional external add-ons, this research investigates internal flow-path modifications to enhance turbulence. Experimental results reveal that models M2 and M3 improved dissipation by 58.12% and 50%, respectively, compared to the standard M1 design. The study demonstrates that efficiency is closely tied to step geometry relative to critical depth, leading to the development of a new empirical formula () for predictive modelling. These findings offer a practical approach to optimising dam safety and flood control by significantly downsizing downstream structures while maintaining high hydraulic performance.
  Keywords: energy dissipation; stepped weirs; hydraulic structures; geometric parameters; dimensional analysis; flood control; empirical model; dam engineering.
  DOI: 10.1504/IJHST.2026.10078270
   
  
• Multi footprint evaluation of Andean hydropower integrating nature-positive water footprint, life-cycle assessment and eco-hydrological resilience in the Mantaro Basin  
  by Araujo Reyes Luis-Donato, Percy Cesar Estrada-Ayre, Percy Eduardo Basualdo-Garcia, Russbelt Yaulilahua-Huacho, Anthony Enriquez-Ochoa, Syntia Porras-Sarmiento, Miriam Liz Palacios-Much 
  Abstract: The scoping review focuses on the combination of the nature-positive water footprint framework and life-cycle assessment (LCA) to assess the sustainability of hydropower production in the Mantaro River basin, one of the main energy sources of the Central Andes. Hydropower in the basin is a source of electricity in Peru and it is placing more strain on fresh water and high altitude ecosystems. This review is a synthesis of multidisciplinary (hydrology, energy systems, and ecosystem science) evidence that was published in 20102025 in accordance with the PRISMA-ScR guidelines. The analysis reveals significant trade-offs between water, land, and carbon footprints and reflects on the eco-hydrological limits and governance lapses which limit nature-positive outcomes. Combining NP-WF and LCA presents prospects of basin-based management policies that optimise the renewable energy production, water-usage efficiency, and biodiversity resilience. The results indicate the necessity of transdisciplinary models to direct the low-carbon energy shifts in the ecologically delicate mountain systems.
  Keywords: water-energy nexus; hydropower sustainability; nature-positive water footprint; life-cycle assessment; Mantaro River basin; MRB; Andean basins; renewable energy transitions.
  DOI: 10.1504/IJHST.2026.10078271