The Soil Conservation Service curve number (SCS-CN) method remains useful for event runoff estimation, although it aggregates several processes into one parameter. The expo-linear rainfall-runoff model was proposed and separates the maximum incremental response, the activation level and its rate, but predicts positive direct runoff when event precipitation is zero. This article proposes a zero-origin correction that preserves the original logistic derivative while enforcing Q(0) = 0. The formulation was evaluated using small experimental catchments in south-central Chile (0.22-1.12 km(2)), CAMELS-CL basins, and then compared with SCS-CN and the original model. A sensitivity analysis considered nine parameter combinations of the Eckhardt baseflow filter. The corrected model produced nearly identical predictive performance to the original formulation across catchments and filter settings, while removing the non-zero runoff artefact. The correction is not intended to guarantee lower RMSE but provides a physically admissible expo-linear formulation for repeated event-based or spatial applications.
This study investigated subsurface water runoff characteristics in two alpine watersheds - NR1 and NR2 - with vegetation coverages of 20.7% and 51.2%, respectively, Mt. Norikura, Northern Japan Alps. We monitored stream level from July to October 2023, conducted chemical and stable isotope analyses on stream, spring, rain, and snowmelt waters, and performed hydrograph separation using SiO2 as a tracer. The total precipitation was 775.8 mm during the monitoring period, and the streamflow was ephemeral in NR1 and perennial in NR2, resulting in runoff ratios of 12.3% in NR1 and 80.5% in NR2. Additionally, stream water in NR2 showed higher ion concentrations and lower temporal variation of d-excess than those in NR1. Also, estimated groundwater runoff is higher in NR2 (458.7 mm) than in NR1 (12.8 mm). These results suggest that runoff characteristics are influenced by vegetation cover and also subsurface flow processes, including the groundwater flow across the topographic watershed boundaries.
Compound drought assessment requires indices that distinguish concurrent meteorological, agricultural, and hydrological deficits. Empirical multivariate drought indices such as TSDI commonly estimate joint probabilities using calendar-month rank-based plotting positions to preserve seasonality, but this reduces effective sample size and can truncate extreme severity. This study derives the Gringorten lower-bound expression, tests finite-sample effects through trivariate Monte Carlo experiments for 20–50-year records and evaluates the truncation mechanisms using observed drought records from the Seyhan and Çoruh River basins in Türkiye. In the 40-year baseline experiment, the empirical lower bound was approximately −2.20. For analytical severity below −2.0, TSDI bias was 0.403, whereas KMDI reduced bias to 0.048 and lowered RMSE by 73.6%; RMSE reductions remained 73–76% across tested record lengths. Basin results confirmed that TSDI reached the theoretical floor, while KMDI resolved lower-tail values below it. Finite-sample resolution should therefore be explicitly considered in compound drought-risk assessment.
Surface debris exerts profound influence on glacial dynamics as it changes the surface ablation and spatial distribution rates. This paper addresses the temporal variation in particle size distribution, sediment load (SSL), suspended sediment concentration (SSC) in the heading stream that flows out of the Glacier for the period (2017, 2018, 2019, 2022, 2023). Analysis of the data shows an increasing trend of SSC in relation to discharge since June and highest sediment load occurring in July and August. Silt particles (31–80%) followed by sand (18–45%) and clay (1–4%) dominated the suspended sediments. The proportions of sand particles were found to be less variable, whereas the proportion of the clay particles varied greatly when historical data of two distinct melt seasons (2004–2006 & 2017–2019) were compared. The poorly sorted sediments delivered are indicative of intense glacial erosion and kurtosis values during the melt seasoning suggest the climatic variations influence the area.
Urban drainage is typically assessed using a limited number of design storms or recorded events, offering only a partial understanding of system performance. This study proposes a framework for the systematic evaluation of urban drainage response at the basin scale across a broad rainfall intensity–duration domain using hydrologic–hydraulic simulations. Simulation results are synthesized into decision-support products, including both local and global indicators. Key outputs include intensity–duration (ID) diagrams, return period maps, and flood extent maps associated with extreme historical events. The framework is demonstrated in a 70% urbanized basin with approximately 460,000 inhabitants in the Buenos Aires Metropolitan Region (Argentina). The approach identified critical rainfall conditions, vulnerable areas, and patterns of hydraulic capacity exceedance. By linking rainfall characteristics, system response, and flood impacts, the framework provides a comprehensive perspective on drainage system behaviour and can support system diagnosis, infrastructure planning, climate change assessments, and urban water management.
