Green and grey roofs have emerged as promising and sustainable measures for effectively managing stormwater in urban catchments. However, there is a gap in the literature in understanding and ...modelling the hydrological performance of these roofs during winter and snow-covered periods in cold climate regions. The present study attempted to address this gap by validating the use of a snow module in simulating the dynamics of snow accumulation and melting of green and grey roofs. Then, the validated model was used to identify and separate the different events that occur in winter (melt only, rainfall only, rain-on-snow) to assess the hydrological performance of six different configurations of green and grey roofs in Trondheim, Norway. The snow module accurately simulated snow accumulation and melting of green and grey roofs. The results showed that rain-on-snow events in winter have longer duration compared to other events including rainfall events in summer. Consequently, rain-on-snow events yield a higher amount of inflow to the roofs compared to rainfall events in summer, despite summer events having higher intensities. The retention and detention performances of green and grey roofs were found to be lowest for rain-on-snow events compared to other types of events, but still yielding significantly lower peak runoffs when compared to standard black roofs. The decrease in retention and detention performances in winter were attributed to the long duration of events, accumulation effect of snow, freezing of roof surface layers, and reduction of evapotranspiration. The study highlights the importance of considering winter conditions in the design of green and grey roofs in cold climates to enhance stormwater management.
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•A snow model was found suitable for modelling snow melt of green and grey roofs.•Developed a method to separate winter events into rain, melt and rain-on-snow events•Rain-on-snow events have the longest duration and yield highest peak runoff.•Green and grey roofs can manage rain-on-snow if designed properly.
In this research article, the authors intend to develop and analyze an epidemic model that describes the progression of acute and chronic HBV in a population. The threshold number R0 was obtained ...using the well-known next-generation matrix approach. The stability of disease-free and disease present states of the proposed model is investigated using the basic reproduction number. Results found during dynamical analysis show that the model exhibits backward bifurcation. To control the spread of infection; vaccination and treatment were introduced as control variables in the model. The key strategy is to decrease the number of acute and chronic infected people with the lowest possible cost. To support the theoretical results, sample simulations were presented at the end of the work.
Four subbasins in the Gandaki River Basin in the southern Himalayan region.
In the southern Himalayan region, gridded precipitation datasets are often used to complement sparse gauge network ...observations in hydrological modelling for water resource assessment. However, the applicability and uncertainty of using these datasets in hydrological modelling remain to be evaluated. In this study, nine high spatial resolution gridded precipitation datasets were used to force a widely used hydrological model to simulate the daily runoff at four hydrological stations in this region. The accuracy of these datasets was evaluated, and the model calibration results and modelling uncertainty were analyzed.
Our analysis revealed large differences among the nine gridded precipitation datasets, and most datasets underestimated the annual precipitation in the low-elevation regions and overestimated that in the high Himalayas. Furthermore, through the adjustments of model parameters, the underestimations of precipitation by gridded datasets were compensated for by the overestimation of glacial melt. Therefore, the model performance was better, and the model uncertainty was lower in basins with higher glacial coverage. Notably, our findings indicated that the performances of gridded precipitation datasets were heterogeneous and that their direct use in hydrological modelling may result in unreasonable hydrological process variables; thus, these datasets should be evaluated and used with caution in water resource assessments in Himalayan regions.
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●Large differences exist among nine commonly used gridded precipitation datasets.●Model uncertainty is estimated using gridded precipitation as forcing data.●Precipitation underestimation is compensated by glacial and snow melt.●The performances of gridded precipitation datasets are heterogeneous.
Climate change imposing additional stressors on groundwater resources globally, thereby predicting groundwater recharge (GR) changes is crucial to sustainably managing water resources, especially in ...the arid endorheic basins. Groundwater in the Endorheic Basins of Northwest China (NWEB) is potentially impacting regional socio-economic output and ecosystem stability due to the imbalance between supply and extraction exacerbated by climate change. Hence, recognizing the impacts of climate change on past and future GR is imperative for groundwater supply and sustainable groundwater management in the NWEB. Here, the impact of historical (1971–2020) and projected (2021–2100) climate changes on GR across the entire NWEB and three distinctive landscape regions (i.e., mountainous, oasis, and desert) were assessed. A coupled distributed hydrologic model (CWatM-HBV model), which integrates the Community Water Model (CWatM) and the HBV model, was run with three shared socioeconomic pathways (SSP1–2.6, SSP2–4.5, and SSP3–7.0) forcing from 10 general circulation models (GCMs) to simulate and analyze the interannual and seasonal variations of GR, along with their driving factors. Over the past 50 years, both precipitation and runoff have undergone significant increases, and leading to a dramatic rise in GR (0.09 mm yr−1). The future annual growth rate of GR is projected to range from 0.01 to 0.09 mm yr−1 from SSP1–2.6 to SSP3–7.0 across the entire NWEB, with the majority of the increase expected during the spring and summer seasons, driven by enhanced precipitation. GR from the mountainous region is the primary source (accounting for approximately 56–59 %) throughout the NWEB with the greatest increase anticipated. Precipitation and runoff have significant influences on GR in mountainous areas, and the impact of precipitation on GR is expected to increase over time. Changes in GR in oasis and desert areas are mainly limited by precipitation variation and increase in the SSP2–4.5 and SSP3–7.0 scenario. Additionally, the processes of glacial retreat and permafrost degradation will complicate the GR dynamics although the process is largely interfered with by anthropogenic environmental changes, especially in oasis-desert systems. The average annual recharge in the NWEB was 8.9 mm in the historical period and 13.6 ± 4.1 mm in the future. Despite an increase in GR due to climate change, groundwater storage is likely to continue to decline due to complex water demands in the NWEB. This study highlights the significance of future precipitation changes for GR and contributes to the understanding of the influence of climate change on groundwater systems and advances the sustainable management of water resources.
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•The glacier hydrological processes in the CWatM model have been improved.•A slight increase in future groundwater recharge may not meet the water demand.•Future increases in runoff variability may reduce the stability of GR within years.•The influence of precipitation on GR is projected to strengthen in the far future.
In most bucket‐type hydrological models, water can only flow from the groundwater to the stream and the flux is based on the groundwater storage. However, many catchments have losing stream sections, ...where streamflow recharges the groundwater. We developed a formulation to represent groundwater recharge by streamwater in a bucket‐type model and tested this formulation for the Panola Mountain Research Watershed to demonstrate its function and assess its performance. The upper reach of the Panola catchment is often dry and highly affected by flow from a bedrock outcrop; further downstream the stream is perennial. We simulated streamflow with the fully lumped version of a bucket‐type model and compared it to (a) a variant with sub‐catchments to more realistically represent the low storage and quick response from the bedrock outcrop and (b) a variant that also includes the bi‐directional exchange between the groundwater and the stream. For all three model variants, we compared simulated and observed streamflow and groundwater dynamics. Although the gain in overall model performance by including the bi‐directional exchange between the groundwater and the stream was small, the explicit representation of this exchange led to better streamflow simulations during drying‐down and wetting‐up periods. For Panola the fluxes along the stream appeared less important than subsurface drainage from the upper sub‐catchment to the downstream sub‐catchment. We recommend considering the bi‐directional fluxes between groundwater and the stream in bucket‐type hydrological models where these processes are important, and the focus of the simulations is on low flow conditions.
Key Points
Formulation of a routine to address losing stream conditions, important for properly modeling low flows and intermittent streams
Implementation of the new routine in a bucket‐type hydrological model
For the Panola Mountain Research Watershed the routine led to better simulations of streamflow during drying‐down and wetting‐up periods
The scaling exponent of a hierarchy of cities used to be regarded as a fractional. This paper investigates a newly constructed system of equation for Hepatitis B disease in sense of Atanganaa–Baleanu ...Caputo (ABC) fractional order derivative. The proposed approach has five distinctive quantities, namely, susceptible, acute infections, chronic infection, immunized and vaccinated populace. By applying some well-known results of fixed point theory, we find the Ulam–Hyers type stability and qualitative analysis of the candidate solution. The deterministic stability for the proposed system is also computed. We apply well-known transform due to Laplace and decomposition techniques (LADM) and Adomian polynomial for nonlinear terms for computing the series solution for the proposed model. Graphical results show that LADM is an efficient and robust method for solving nonlinear problems.
Land use and land cover (LULC) changes are continuous phenomena, often driven by natural and anthropogenic factors. In Ethiopia, a conversion of forest and grass lands into cultivated and urbanized ...lands has been reported. While such changes are known to have multidirectional impacts on river flows, erosion and sedimentation, and the socio-economic situation within a catchment, there is a lack of assessment on the scale and rate of these changes, and consequent impacts. This study quantifies the rate of LULC in the Gumara catchment (1413 km2), an important tributary to Lake Tana in northwest Ethiopia. Landsat images of three years (1986, 2001 and 2015) were processed using the supervised classification method. An extensive field survey generated over 150 ground truth points, which were used in the classification and accuracy assessment process. Then, a conceptual rainfall-runoff model (HBV) was calibrated and validated to assess the impacts of LULC changes on water balance components - evapotranspiration, soil moisture, groundwater recharge and runoff. Additionally, the decadal means and trends of precipitation and discharge were analysed to further examine and quantify the observed changes (if any).
A reasonably reliable LULC classification was achieved, with an overall accuracy of 90%. The results indicated that the catchment area under forest and grass land was about 11 and 18%, respectively, in 1986, which reduced to 5 and 10%, respectively, in 2015. In contrast, cultivated land increased from 70% in 1986 to 82% in 2015. Contrary to the expected impact of these LULC changes on hydrology, the HBV model, indicated only a slight change in the water balance components (±5%). Runoff and all other water balance components remained more or less stable despite considerable LULC changes. However, the uncertainties encountered in the modelling process (e.g. model structure, LULC representation) could have masked the LULC impacts on hydrology. This was supported by the significant increase in the observed discharge indicated by the statistical analysis, even in view of no substantial changes in precipitation. Therefore, LULC could cause considerable increase in discharge, which needs further testing (e.g. through physically based modelling with detailed inclusion of LULC processes).
•Substantial land use and land cover changes occurred in the Gumara catchment (1986–2015).•The HBV model indicated only a slight change in the water balance components (±5).•Trend analysis showed a significant increase in observed discharge.
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