Hydrological data in the form of stream flow is very scarce in most developing countries. This affects the planning and management of urban watersheds. Therefore, it is necessary to estimate peak ...discharge from rainfall using hydrologic models based on some measurable watershed characteristics. This study aims to model the rainfall-runoff process from a typical urban watershed using Hydrologic Engineering Center Hydrological Modeling System (HEC-HMS) software. The catchment basin has a total area of 21.91 km2, and a dendritic stream system. Soil Conservative Services (SCS) Curve number was used for getting excess rainfall from total rainfall, SCS dimensionless unit hydrograph for converting the excess rainfall to direct runoff and Muskingum for the channel routing. The rainfall-runoff simulation was conducted using six (6) rainfall events. Model calibration and validation were done using optimized parameters and the result shows a reasonable fit between the observed and simulated hydrograph. The model result has an RMS error of 1.5 m3/s, and a Nash-Sutcliff of 0.585. It is concluded that the model can be used to predict runoff from rainfall with reasonable accuracy. The result can be used for watershed planning and management.Keywords: HEC HMS, rainfall, runoff
HEC HMS merupakan salah satu aplikasi pemodelan yang dapat digunakan untuk memodelkan nilai limpasan harian maupun bulanan berdasarkan karakteristik DAS. Tujuan penelitian ini adalah 1) Mengkaji ...karakteristik fisik DAS Serang yang direpresentasikan oleh nilai curve number (CN) 2) Mengkaji karakteristik aliran yang berupa debit puncak, volume outflow, dan waktu puncak dari hidrograf banjir terukur dengan hasil pemodelan menggunakan HEC-HMS. Nilai CN ditentukan menggunakan metode SCS-CN. Analisis hidrograf banjir dilakukan menggunakan HEC-HMS meliputi perhitungan presipitasi menggunakan gage weight, volume runoff menggunakan SCS CN, direct runoff menggunakan SCS-UH, dan baseflow menggunakan constant monthly. Hasil penelitian menunjukkan CN pada tahun 2019 memiliki nilai 83 pada kondisi AMC I. Hasil kalibrasi menunjukkan nilai objective function dengan metode Peak-Weighted RMS Error cukup baik yaitu sebesar 2.2% dengan selisih antara debit puncak simulasi dan observasi yang nilainya masing-masing adalah 21.2 m3/s dan 21.6 m3/s. Secara keseluruhan, hasil uji statistik validasi diketahui bahwa model HEC-HMS menghasilkan hidrograf model yang sangat baik dilihat dari nilai NSE, R2 dan PBIAS.HEC HMS is a modeling application that can be used to model daily and monthly runoff values based on watershed characteristics. The objectives of this study are 1) to examine the physical characteristics of the Serang watershed which is represented by the curve number (CN) 2) to examine the flow characteristics in the form of peak discharge, outflow volume, and peak time of the flood hydrograph measured by modeling results using HEC-HMS. The CN value is determined using the SCS-CN method. Flood hydrograph analysis was performed using HEC-HMS including calculation of precipitation using gage weight, volume runoff using SCS CN, direct runoff using SCS-UH, and baseflow using constant monthly. The results showed that CN in 2019 had a value of 83 under AMC I conditions. The calibration results showed that the objective function value with the Peak-Weighted RMS Error method was quite good, namely 2.2% with the difference between the simulation peak discharge and the observation, each of which was 21.2 m3. /s and 21.6 m3/s. Overall, the results of the statistical validation test show that the HEC-HMS model produces a very good hydrograph model seen from the NSE, R2 and PBIAS values.
The rapid development of Yogyakarta has made city development increase. This construction continues to expand the reach of impervious surfaces. As a result, surface runoff and maximum discharge have ...increased, overflowing up to urban drainage. This study aimed to analyze the maximum discharge of the watershed based on design storms with 2, 5, 10, and 25-year return periods, used for flood control considerations. The urban flood was modelled using HEC-HMS. The results showed that the contribution of discharge flow in each segment is influenced by the dominance of land use, in which the segment dominated by dense settlements has a high contribution to the maximum discharge. The flow contribution is due to the high curve number value, which corresponds to the high surface runoff. The peak discharge of watersheds with return periods of 2, 5, 10, and 25 years are 8 m3/s, 20.1 m3/s, 29.9 m3/s, and 44.1 m3/s, respectively.
Kerala state (India) experienced a devastating flood event during the month of August 2018. While an extreme rainfall event (ERE) was the primary reason for this flood, there was criticism at various ...levels that the authorities failed to manage the flood effectively through reservoir operations. One of the worst affected basins, Periyar River Basin (PRB), received a 145 year return period rainfall. This study reports the results and analysis of a modelling exercise using HEC-HMS to simulate and analyse the role of dams, as well as reservoir operations, on the flood of August 2018. The results indicated that the role of releases from the major reservoirs in the PRB resulting in the flood havoc was less. The analysis suggested that reservoir operations could not have helped in avoiding the flood situation as only 16–21% peak attenuation was possible by emptying the reservoir in advance, as the bulk of runoff to the flooding was also contributed by the intermediate catchments without any reservoirs to control. Further, the attenuated flood peak due to advance emptying of the reservoir would still be almost double the safe carrying capacity of the river section at Neeleswaram. In addition, the reliability of the rainfall forecast at higher lead times is also a concern for the reservoir operation. It is noted that the probability of EREs of this kind in the month of August in PRB is very small (0.6%), and therefore any planned operation could not have helped in mitigating floods of such magnitude without a reliable EREs forecast coupled with reservoir inflow forecasting system and optimized set of reservoir operational policies.
The paper aims at simulating streamflow using Hydrologic Engineering Center Hydrological Modelling System (HEC-HMS) under different Representative Concentration Pathways (RCP's) to access the impact ...of climate change on hydrological regime of Bhagirathi River at Tehri Dam. The input for the study is precipitation and temperature which are obtained from remote-sensing data. The temperature and precipitation data daily products are obtained from Tropical Rain Monitoring Mission (TRMM) and Atmospheric Infrared Sounder (AIRS) missions and the respective future anomalies were obtained from World Bank Climate Change Knowledge Portal (CCKP). The streamflow simulation is done for RCP's 4.5 and 8.5 under the models csiro_mk3_6_0, bcc_csm1_1, ccsm4 and mri_cgcm3. The study found that the combination of remote-sensing data and HEC-HMS model has been successful in simulating streamflow in the region. The region will experience an increase in streamflow discharge under changing climate over the next coming years. The simulation also indicates that there will be a change in temporal distribution pattern of the discharge. Amidst these uncertainties, the predictions also give an insight into the planning and management of constructed or to be constructed hydraulic structures in the basin.
Floods are recurrent phenomena with significant environmental and socio-economic impacts. The risk of flooding increases when land use changes. The objective of this research is to detect land cover ...changes via Sentinel-2 images in the Umia Basin (Galicia, NW Spain) in 2016–2021 and to analyse the associated flood risk. This study focuses on how forest use and nature-based solutions (NBS) can reduce the risk and hazard of flooding in cities and crops in the high-risk area. A flood simulation was performed with the land use obtained from Sentinel-2 (Observed) and three more simulations were performed changing the location of afforestation and NBS, i.e. “S-Upstream”, “S-Downstream” and “S-Total”. Finally, the environmental, economic and social impacts of the scenarios designed and estimated are analysed and discussed. Land cover change was successfully monitored with Sentinel-2 imagery. The catchment area showed noteworthy changes in land use, most notably for the category of trees, which covered 6700 ha in 2016 and 10,911 ha in 2021. However riparian vegetation decreased by almost 11%. For the flood hazard simulations, an average reduction in peak discharge was obtained for all three scenarios (9.3% for S-Up; 8.6% for S-Down and 13% for S-Total). From the economic perspective, all three scenarios show a positive net present value for the period studied. However, S-Down is the scenario with the lowest benefits (€15,476,487), while S-Up and S-Total show better values at €29,580,643 and €65,158,130 respectively. However, investment cost is much higher for the S-Total scenario, and upstream actions affect the whole catchment, so S-Up is the best decision. This study concludes that the information provided by satellites is a large-scale analysis tool for small heterogeneous plots that facilitates the comprehensive analysis of a territory. This information can be incorporated into flood analysis models, facilitating simulation through the use of NBS. It has been proven that the use of reforestation upstream only is almost as beneficial as reforestation in the entire catchment and is economically more viable. This confirms that the methodology used reduces flood hazard, despite the territorial complexity, facilitating decision making on the use of NBS.
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•Random Forest provided a classification accuracy of 83.18%•The NBS method used mitigates flood hazard in all three simulations•Environmental and social benefits exceed costs in all three simulations•Tools and the use of NBS used enhance the achievement of several SDGs•The use of NBS is more optimal upstream than downstream
•0.11° and 0.44° RCMs are compared in four catchments using climate and flow indices.•The 0.11° simulations had superior skill in one catchment with complex topography.•The RCM flow simulation range ...is large for all catchments at both resolutions.•Bias correction improves the monthly but not the daily temporal variability.•Double Gamma quantile mapping outperforms the single Gamma quantile mapping.
Regional Climate Models (RCMs) are an essential tool for analysing regional climate change impacts, such as hydrological change, as they provide simulations with more small-scale details and expected smaller errors than global climate models. There has been much effort to increase the spatial resolution and simulation skill of RCMs (i.e. through bias correction), yet the extent to which this improves the projection of hydrological change is unclear. Here, we evaluate the skill of five reanalysis-driven Euro-CORDEX RCMs in simulating precipitation and temperature, and as drivers of a hydrological model to simulate river flow on four UK catchments covering different physical, climatic and hydrological characteristics. We use a comprehensive range of evaluation indices for aspects of the distribution such as means and extremes, as well as for the structure of time series. We test whether high-resolution RCMs provide added value, through analysis of two RCM resolutions, 0.44° (50 km) and 0.11° (12.5 km), which are also bias-corrected employing the parametric quantile-mapping (QM) method, using the normal distribution for temperature, and the Gamma (GQM) and Double Gamma (DGQM) distributions for precipitation. The performance of these is considered for a range of meteorological variables and for the skill in simulating hydrological impacts at the catchment scale.
In a small catchment with complex topography, the 0.11° RCMs clearly outperform their 0.44° version for precipitation and temperature, but when used in combination with the hydrological model, fail to capture the observed river flow distribution. In the other (larger) catchments, only one high-resolution RCM consistently outperforms its low-resolution version, implying that in general there is no added value from using the high-resolution RCMs in those catchments. Both resolutions produce river flow simulations that cover the observed flow duration curve, but the ensemble spread is large and therefore the simulations are difficult to use in practice. GQM decreases most of the simulation biases, except for extreme precipitation and high flows, which are further decreased by DGQM, which also reduces the multi-model simulation spread. Bias correction does not improve the representation of daily temporal variability measured by the Nash-Sutcliffe Efficiency Index, but it does for monthly variability, in particular when applying DGQM, which reduces most of the simulation biases. Overall, an increase in RCM resolution does not imply a better simulation of hydrology and bias-correction represents an alternative to ease decision-making.
In the 1960s, Lake Chad (LC) was one of the largest inland water body on the earth and since then, it has extremely shrunk from a surface area of 25,000 km2 to 2000 km2. The present study determines ...hydro-climatic changes in the active parts of the Lake Chad basin by using trend analysis and the causes of declining stream flow to LC due to human interventions and climate variability by using a hydrological approach. One approach, which is used to estimate changes in stream flow due to climate variability, is also modified in this study. Trend results showed that mean temperature exhibited very strong increasing trends, with a mean rise of 1.4 °C for 1951–2015, while precipitation presented very weak to strong declining trends, with an overall decline of 15%. Regarding stream flow, all major rivers showed very strong downward trends, resulting in 67% decline. The northern and eastern regions were the most impacted areas in the basin regarding decreasing precipitation and increasing temperature. The hydrological approach showed that decreasing stream flow to LC varied between 34% and 45% in different decades. In general, human activities attributed a 66% decline in stream flow and climate variability 34% for the impacted period (1972–2013) relative to 1951–1971. Only during 1982–1991, climate variability caused most reduction (59% of total) in stream flow because of devastating drought during this period. Since stream flow to LC was mostly affected by human activities, proper water resources planning and sustainable management are necessary but under the umbrella of considering changing climate.
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•Impacts of climate variability and human activities were assessed using hydrologic approach.•Human activities caused more reduction (66%) in inflow to Lake Chad than climate variability.•Climate variability was assesses using Mann-Kendal and Sen's slope methods.•Highly significant increasing trends were observed, with an increase of 1.4 °C/65 yrs.•Moderate signals of decreasing trends were explored, with decline of 15%/65 yrs.
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