Model MIKE Research Articles

Assessment of regional inter-basin groundwater flow using both simple and highly parameterized optimization schemes

The need for regional-scale integrated hydrological models for the purpose of water resource management is increasing. Distributed physically based coupled surface-subsurface models are usually complex and contain a large amount of spatio-temporal information that leads to a relatively long forward runtime. One of the main challenges with regard to regional-scale inverse modeling relates to parameterization and how to adequately exploit the information embedded in the existing observational data while avoiding parameter identifiability issues. This study examined and compared the calibration of a “highly parameterized” model with a “classical” unit-based parameterization scheme in which the dominant geological features were assumed to be known. The physically based coupled surface-subsurface model MIKE SHE was used for conducting the study of five river basins (4,900 km2) in central Jutland in Denmark, characterized by heterogeneous geology and a considerable amount of groundwater flux across topographical catchment boundaries. The results indicated that introducing more flexibility in the parameter estimation process through a regularized approach significantly improved the model performance, in particular head and water balance errors. The highly parameterized calibration results additionally provided very useful insights into the model deficiencies in terms of conceptual model structure and incorrectly imposed boundary conditions. Furthermore, the results from data-worth analysis indicated that the highly parameterized model has more effectively utilized the information in the dataset compared to a traditional unit-based calibration approach.

PEMODELAN MIKE21 DALAM KEJADIAN BANJIR ROB MENJELANG GERHANA BULAN DI PESISIR SEMARANG

Pesisir Semarang merupakan wilayah yang rentan terkena dampak bencana banjir rob. Hampir setiap bulan wilayah tersebut tergenang akibat pasang air laut. Peristiwa banjir rob yang paling diingat publik adalah saat terjadi menjelang gerhana bulan tanggal 31 Januari 2018. Peringatan dini informasi banjir rob perlu dibuat dengan tingkat akurasi tinggi dan dalam bentuk yang mudah dipahami masyarakat untuk kepentingan mitigasi. Tipe pasang surut (pasut) di Pesisir Semarang perlu diidentifikasi untuk mengetahui kecenderungan waktu kejadian banjir rob. Model Hidrodinamika Mike 21 digunakan untuk mengolah data pengamatan pasut sepanjang tahun 2017 menjadi informasi prakiraan pasut sepanjang bulan Januari 2018. Nilai akurasi prakiraan pasut Mike 21 diukur dengan Root Mean Square Error (RMSE), serta dibandingkan dengan keakurasian prakiraan pasut dari Pushidrosal (Pusat Hidrografi dan Oseanografi TNI Angkatan Laut) dan BIG (Badan Informasi Geospasial). Hasil prakiraan pasut terbaik selanjutnya diolah pada aplikasi ArcGIS, dengan mengambil nilai prakiraan pasang tertinggi pada hari kejadian sebagai data input untuk pembuatan peta luas genangan banjir rob. Puncak kejadian banjir rob cenderung terjadi pada pukul 06.00 WIB dan 17.00 WIB, yang mana berdasarkan hasil identifikasi di Pesisir Semarang termasuk tipe pasang surut harian ganda. Prakiraan pasut dari Mike 21 memiliki nilai RMSE terbaik. Nilai RMSE prakiraan pasut Mike 21, Pushidrosal dan BIG berturut-turut bernilai 10 cm, 30 cm dan 22 cm. Nilai pasut tertinggi baik model Mike 21 maupun hasil pengamatan terjadi pukul 20.00 WIB. Pemodelan nilai pasut tertinggi dari Mike21 sebesar 122 cm menghasilkan peta luas genangan banjir rob sebesar 1753.35 ha, sedangkan nilai pasang tertinggi hasil pengamatan sebesar 133 cm menghasilkan 185.31 ha lebih luas.

Optimized Numerical Model Based Assessment of Wave Power Potential of Marmara Sea

Marmara Sea, located between Black Sea and Aegean Sea, is an important sea for ocean engineering activities. In this study, wave power potential of Marmara Sea was investigated using the third generation spectral wind-wave model MIKE 21 SW with unstructured mesh. Wind data was obtained from ECMWF ERA-Interim re-analyses wind dataset at 10 m with a spatial resolution of 0.1° for the period of 1994 to 2014. The numerical model was calibrated with measured wave data from a buoy station located in Marmara Sea. Mesh optimization was also performed to obtain the most suitable mesh structure for the study area. This study is the first that dealt with the determination of wave energy potential of Marmara Sea. The numerical model results are presented in terms of monthly, seasonal and annual average of wave power flux (kW m−1). The maximum wave power flux is 1.13 kW m−1 and occurs in November. The overall annual mean wave power flux during 1994–2014 is found to be 0.27 kW m−1 in the offshore regions.

Study on Technical Schemes for Major Pollutants Emission Reduction in Beijing North Canal River Basin Based on Watershed Water Quality Target Management

Water quality target management in watershed is the fundamental choice of city rivers suffering both serious pollution and severe water shortage. In this study, we performed a case study regarding river pollution control plan based on water quality target management in the North Canal River catchment of Beijing section, in order to obtain effective water quality improvement programs. The ammonia nitrogen (NH3-N) and chemical oxygen demand (COD) were taken as the main controlling pollutants. Water quality targets and basic water quality improvement scenarios were set up considering different intensities of population regulation scenarios and gradually strengthening emission control measures. The MIKE11 model was adopted to simulate the effects of a range of water quality improvement scenarios. Results indicated that the basic scenarios could dramatically improve the surface water environment. However, additional intensive and combined measure programs should be implemented to ensure that the water quality would basically meet the targets of corresponding water function zones. The results highlight the need to implement water conservation in water shortage urban river basin and show the importance of enhancing drainage communication and conducting ecological water replenishment in such kind basins. It is expected to provide a reference for the water environment management practice of other metropolis in the world facing both crisis of water resource shortage and water environment pollution.

Study on Technical Schemes for Major Pollutants Emission Reduction in Beijing North Canal River Basin Based on Watershed Water Quality Target Management

Water quality target management in watershed is the fundamental choice of city rivers suffering both serious pollution and severe water shortage. In this study, we performed a case study regarding river pollution control plan based on water quality target management in the North Canal River catchment of Beijing section, in order to obtain effective water quality improvement programs. The ammonia nitrogen (NH3-N) and chemical oxygen demand (COD) were taken as the main controlling pollutants. Water quality targets and basic water quality improvement scenarios were set up considering different intensities of population regulation scenarios and gradually strengthening emission control measures. The MIKE11 model was adopted to simulate the effects of a range of water quality improvement scenarios. Results indicated that the basic scenarios could dramatically improve the surface water environment. However, additional intensive and combined measure programs should be implemented to ensure that the water quality would basically meet the targets of corresponding water function zones. The results highlight the need to implement water conservation in water shortage urban river basin and show the importance of enhancing drainage communication and conducting ecological water replenishment in such kind basins. It is expected to provide a reference for the water environment management practice of other metropolis in the world facing both crisis of water resource shortage and water environment pollution.

Saltwater Intrusion Function and Preliminary Application in the Yangtze River Estuary, China

More attention has been paid to saltwater-intrusion-related problems in recent years. In this research study, a saltwater intrusion function in the Yangtze River Estuary (YRE) was constructed based on the theory of the interactions between energy accumulation and impedance. A MIKE21 model was used to simulate the hydrodynamics of the YRE. Then, through the analysis of the relationships between the river discharge conditions, tidal ranges, and saltwater intrusion, it was determined that, under certain river discharge conditions, the tidal ranges and salinity levels at the stations in the southern branch (SB) of the YRE conformed to S-shaped curve characteristics. Also, the tidal ranges and salinity excessive area rate (SEAR) displayed similar characteristics. Furthermore, the river discharge conditions were also found to match the S-curve characteristics between the two aforementioned relationship features. Therefore, the saltwater intrusion function of the YRE was constructed based on the previously mentioned development rules. Also, the applied quantification methods were elaborated, and the values of the parameters were determined. As a result, the critical river discharge (more than 10,000 m3/s) was obtained, which could withstand large-scale saltwater intrusions. When the river discharge was greater than 30,000 m3/s, the area was considered to be basically without salt water intrusions, and the estuarine ecology was in an optimal state. The saltwater intrusion losses from 2005 to 2015 are also calculated. These findings have important reference value for water dispatching of the YRE in the dry season.

Comparison of daily flows simulated for the year 2060 on the Kaczawa River for various scenarios of climate change by simple time series analysis

In this paper a time series analysis for daily flow simulations according three climate change scenario for Kaczawa River a left side tributary of the Odra River in south-west Poland is presented. The flow sequences were simulated using the hydrological model MIKE SHE and the spatial SWGEN meteorological data generator. Meteorological data for the hydrological model were generated based on data from 24 meteorological stations and 35-year daily data from the Institute of Meteorology and Water Management of the National Research Institute (IMGW). Data were generated for future climate condition for 2060 according GISS Model E, HadCM3, and GFDL R15 scenarios as well for the present conditions. The year 2000 was used as a reference year. The results obtained on the basis of a simple time series analysis point to small changes in flows for current and simulated conditions for 2060 for the Kaczawa River.

Unidimensional, non-stationary modeling of a high mountain river in southern Ecuador

Floods represent a severe cause of deaths and economic loss. In order to prevent, mitigate, and reduce flood risks and their consequences, hydraulic models allow analysing and mapping floods. The results of an appropriate model that works under local conditions are a valuable tool for local governments leading to sustainable management of floodplains. Around the world, high-mountain rivers have been poorly modelled; their orography and data scarcity present an extra research difficulty. Considering that all one-dimensional models assume that the river bed slope is small, this study evaluated two widely applied one-dimensional models: Mike11 and HEC-RAS, for modelling a high mountain river. Their best configuration under complex topographical conditions and their potential use was assessed by calibration and validation of the models. We found that the HEC-RAS model was not able to define a stable solution of the hydrodynamic modelling of the river, while Mike11 yielded stable results. Furthermore, the validation of the Mike11 model showed good performance. This study sets a precedent in the 1D modelling of high-mountain rivers with data scarcity.

Multi-objective calibration of MIKE SHE with SMAP soil moisture datasets

Abstract Root zone soil moisture plays an important role in water storage in hydrological processes. The recently launched Soil Moisture Active Passive (SMAP) mission has produced a high-resolution assimilation product of global root zone soil moisture that can be applied to improve the performance of hydrological models. In this study, we compare three calibration approaches in the Beimiaoji watershed. The first approach is single-objective calibration, in which only observed streamflow is used as a benchmark for comparison with the other approaches. The second and third approaches use multi-objective calibration based on SMAP root zone soil moisture and observed streamflow. The difference between the second and third approaches is the metric used to characterize the root zone soil moisture. The second approach applies the mean, which was commonly used in previous studies, whereas the third approach applies the hydrologic complexity μ, a dimensionless metric based on information entropy theory. These approaches are implemented to calibrate the distributed hydrological model MIKE SHE. Results show that the root zone soil moisture simulation is clearly improved, whereas streamflow simulation suffers from a slightly negative impact with multi-objective calibration. The hydrologic complexity μ performs better than the mean in capturing the features of root zone soil moisture.

Numerical Modelling of Ballast Water Dispersion in Different Bioregions along the Coast of India

Aquatic organisms and pathogens may become major threats to the coastal and marine environment when introduced into a region beyond their natural distributions through ballast water (BW). Coastal currents induced by tides and winds, especially ebb currents, may facilitate the spread of these marine organisms along nearshore and inshore areas. Numerical modelling of hydrodynamics is an effective tool to track the dispersion of these organisms in the receiving water body through BW release. Particle transport models can be used to track the advection and dispersion of these organisms. Alternatively, the difference in salinity of the BW and coastal waters can be used as a tracer to estimate the dispersion pattern. Tides and winds present in the region at the time of BW release are responsible for the dispersal of the particles present in BW discharge. Based on advection and dispersion processes, the transport of the marine organisms present in the BW can be studied using numerical models. Numerical modelling studies were carried out using the 2-D hydrodynamic model MIKE21 HD, to understand the pattern of BW dispersion at select bioregions along the east and west coasts of India. Mangalore Port located along the west coast in Bioregion-I (CIO-I) and Chennai Port on the east coast in Bioregion-II (CIO-II) were selected for the modelling study. Results obtained from ballast water dispersion modelling studies will be useful for developing and assisting port-based ballast water management programmes for CIO-I and CIO-II regions. The currents are predominantly tide driven near the ports situated along the west coast and the circulation exhibited reversals associated with the tidal currents. However, along the east coast of India, the particles largely followed coastal currents - advected either southward or northward under the influence of prevailing coastal currents in the offshore region and tidal reversals showed had less impact. This information proved useful for determining suitable locations for BW discharge and monitoring points for field sampling in connection with BW release.

Water quality analysis and model simulation for the second largest polluted lake in Egypt

This study investigated the spatial variation in the water quality parameters of Burullus Lake using multivariate analysis and MIKE21 model. The lake was classified into zone-1 at north-east (Z1), zone-2 at south-east (Z2), zone-3 at north-middle (Z3), zone-4 at south-middle (Z4), zone-5 at north-west (Z5), zone-6 at south-west (Z6), and zone-7 at west (Z7). The obtained parameters were temperature 21.5±5.0 ºC, pH 8.2±0.6, dissolved oxygen (DO) 5.9±1.0 mg/L, biological oxygen demand (BOD) 23.9±5.7 mg/L, NH3-N 2.5±0.3 mg/L, NO2-N 1.9±0.3 mg/L, NO3-N 1.2±0.3 mg/L, PO4-P 1.9±0.3 mg/L, SiO4 3.2±0.1 mg/L, Chlorophyll-a (Chl-a) 88.2±10.8 µg/L, and salinity 3.2±1.0 g/L. Principal component analysis showed that agricultural drainage water was the key factor influencing the water quality characteristics of Burullus Lake. Water quality index (WQI) varied between “Bad” to “Medium”, suggesting that the lake wasn’t suitable for irrigation and fish growth; however, it was appropriate for some aquatic life. A MIKE21 model was developed to provide a recommendation scenario that could be used to enhance the water quality of Burullus Lake. By improving the water quality of precise drains (namely drains 7 and 8), the WQI at Z4 and Z6 modified from “Bad” to “Medium”. The period required to achieve this self-purification was 5 months.

Modelling seasonal flows alteration in the Vietnamese Mekong Delta under upstream discharge changes, rainfall changes and sea level rise

ABSTRACTThe Vietnamese Mekong Delta (VMD) is one of the world’s most vulnerable deltas to climate change and sea level rise. Adequate understandings of future hydrological changes are crucial for effective water management and risk-proofing, however, this knowledge body is currently very limited. This study quantifies the responses of the VMD’s river flow regime to multiple stimuli, namely future upstream inflow variation, local climate change, and sea level rise. The one-dimensional hydrodynamic model MIKE 11 was used to simulate discharges and water levels across the delta. We developed four scenarios to represent changes in the upstream discharges, precipitation changes and sea level rise, covering the 2036–2065 period. We downscaled climate data and applied three bias-correction methods for five General Circulation Models (GCM), and two Representative Concentration Pathways (RCPs). The climate change projections show similar trends of increasing wet season precipitation and decreasing dry season precipitation. However, cross-scenario variations are sometimes large, depending on the individual GCMs, the RCPs and specific locations. The hydraulic simulation results indicate that, under discharge changes between −20% and +10%, combined with in-delta precipitation variations during the dry season, river discharges at the four representative stations could reduce substantially from −2.5% to −100.2%. During the wet season, the calculated river discharges show increase between 7.3% and 46.7% under four considered scenarios. Substantial changes in the VMD’s river flow regime could have potentially serious implications for water management, especially saltwater intrusion, and therefore calling for timely adaptation measures.

The application of ship oil spill risk prediction in Dongying emergency capacity planning

This study combines the hydrodynamic prediction model MIKE21 and the oil spill model OILMAP. Using the hydrodynamic prediction model to provide the accurate tidal current field for oil spill model, we apply oil particle tracing method and stochastic simulation method to predict and evaluate the risk of oil spill in the planned port area. The numerical simulation results show that the current and the wind will directly affect the range and trajectory of the oil film. Once the oil spill accident happens, the area with probability greater than 70% is about 191.5km2, which is mainly affected by 5km within two sides of port. Through risk prediction and assessment, we can provide necessary support for the regional emergency forces.

Numerical modelling of waves and surge from Cyclone Chapala (2015) in the Arabian Sea

Cyclones cause significant loss of life and damage to properties, ecosystems and marine structures and facilities. Cyclone modelling results are used for deriving robust design conditions for coastal and marine structures and facilities. The results are also used for emergency planning and decision-making to estimate potential loss of life, damage to properties and marine facilities and to develop rescue and mitigation measures and plan clean-up operations. Royal HaskoningDHV (hereafter RHDHV) has set up regional tidal hydrodynamic and wave models covering the Arabian Sea to provide data to address the above issues. Over the course of a number of studies a total of 30 major cyclones have been identified in the Arabian Sea since 1945. Cyclone Chapala (28 October – 4 November 2015) was found to be the second strongest cyclone event since 1945 (the strongest being Cyclone Gonu in 2007). As less information is available on Cyclone Chapala, this paper has concentrated on this event to illustrate the use of numerical modelling to simulate waves and surge generated by cyclones. The MIKE21 model suite has been used to investigate this cyclone and sample results from the wave and surge modelling are presented in this paper for illustration purposes. The models could be used to simulate any cyclone generated within the Arabian Sea. The methodology described in this paper for modelling waves and surge in the Arabian Sea could also be applied to simulate this type of events at other sites around the world.

IMPACTS OF CLIMATE CHANGE AND SEA LEVEL RISE ON SALINITY INTRUSION IN THE LOWER DONG NAI RIVER SYSTEM

Ho Chi Minh City (HCMC) is ranked among the top 10 cities in the world most likely to be severely affected by climate change and sea level rise (SLR). This study was to assess the impacts of change of upstream flow and sea level rise due to climate change on salinity intrusion in HCMC. The MIKE 11 model with modules hydrodynamic (HD) and advection-dispersion (AD) was applied to this problem by setting up the whole lower Dong Nai river system. Based upon the observed water level and salinity concentration data in 2009, the calibration and validation results indicated that the MIKE11 model was able to simulate the streamflow and salinity concentration with NSE values exceeding 0.6 for both calibration and validation periods. As a result, the differences in salinity concentration under climate change and SLR scenarios were analyzed. The simulated results illustrate that the saltwater will move inland in the future, especially in the dry season.

Hydrological response to climate change in a high altitude catchment

Different climate models are linked to the coupled river and hydrological model MIKE SHE-MIKE-11 to evaluate the future impact of climate change on hydrology in the Lidder sub basin of the Jhelum Basin. The coupled hydrological model was calibrated against the observed stream flow data at Sheeshnag gauging station. The output of the model in the form of snow cover percentage was validated with the high resolution satellite-based Modis data. The outputs from five different global climate models for IPCC A1B emission scenario for future (2025, 2050, 2075 and 2100) emission scenarios were applied on a hydrological model. It was observed that at the end of 21st century the ET losses in the region is increasing, snow storage component is decreasing which is further causing the runoff in the river to increase at the end of 21st century. The contribution of base flow to the discharge in the Lidder River is increasing under all climate models except for incm3 model.

Hydrological response to climate change in a high altitude catchment

Different climate models are linked to the coupled river and hydrological model MIKE SHE-MIKE-11 to evaluate the future impact of climate change on hydrology in the Lidder sub basin of the Jhelum Basin. The coupled hydrological model was calibrated against the observed stream flow data at Sheeshnag gauging station. The output of the model in the form of snow cover percentage was validated with the high resolution satellite-based Modis data. The outputs from five different global climate models for IPCC A1B emission scenario for future (2025, 2050, 2075 and 2100) emission scenarios were applied on a hydrological model. It was observed that at the end of 21st century the ET losses in the region is increasing, snow storage component is decreasing which is further causing the runoff in the river to increase at the end of 21st century. The contribution of base flow to the discharge in the Lidder River is increasing under all climate models except for incm3 model.

Spatial Distribution of the Baltic Sea Near-Shore Wave Power Potential along the Coast of Klaipėda, Lithuania

Wave power is an abundant source of energy that can be utilized to produce electricity. Therefore, assessments of wave power resources are being carried out worldwide. An overview of the recent assessments is presented in this paper, revealing the global distribution of these resources. Additionally, a study, which aims to assess the spatial distribution of the Baltic Sea near-shore wave power potential along the coast of Klaipėda (Lithuania), is introduced in this paper. The impacts of the wave propagation direction and decreasing depth on wave power resources were examined using the numerical wind-wave model MIKE 21 NSW. The wave height loss of the design waves propagating to shore was modelled, and the wave power fluxes in the studied depths were calculated using the JONSWAP wave spectrum modified for the Baltic Sea. The results revealed that all waves that propagate to the shore in the Baltic Sea near-shore area along the coast of Klaipėda from 30 m depth to 5 m depth lose at least 30% of their power. Still, most common waves in this area are low, and therefore, they start to lose their power while propagating to the shore at relatively low (10–14 m) depths. To turn this into an advantage the wave power converter would have to work efficiently under low power conditions.

Method of Improving the Water Quality of Polluted Rivers Based on the MIKE11 Model

In order to seek ways to improve the quality of polluted rivers, this study selected the heavily polluted Yinghe River in China for study, as there is a requirement to improve water quality from the Yangtze River to the Yinghe River. The permanganate index and ammonia nitrogen are the main pollutant targets for the Yinghe River. This study applies MIKE11 to set up a one-dimensional model of the hydrodynamics and water quality using a numerical simulation method to determine the optimal method for river water quality improvement. The simulation experiment tests the influence of factors, such as the supplementary water flow, replenishment water quality, water replenishment position, and method of water supply to improve the water quality. The simulation results indicate that water quality improvement can be simulated with the hydrodynamic module (HD) and the convective diffusion module (AD) combined with the rainfall runoff module (NAM) in the MIKE11 model. In practice, the option with the best replenishment effect is to use class Ⅲ at point 1 and to use class Ⅳ at points 2 and 3 when the supplementary water flow rate is 10% of the river bottom flow. The reduction in permanganate index and ammonia nitrogen was, respectively, 72.3% and 55.7%, and over 85% of the study area reached the standard of class Ⅳ water quality. This provides a new method for river pollution control.

Effects of sea level rise, land subsidence, bathymetric change and typhoon tracks on storm flooding in the coastal areas of Shanghai

We compared the effects of three key environmental factors of coastal flooding: sea level rise (SLR), land subsidence (LS) and bathymetric change (BC) in the coastal areas of Shanghai. We use the hydrological simulation model MIKE 21 to simulate flood magnitudes under multiple scenarios created from combinations of the key environmental factors projected to year 2030 and 2050. Historical typhoons (TC9711, TC8114, TC0012, TC0205 and TC1109), which caused extremely high surges and considerable losses, were selected as reference tracks to generate potential typhoon events that would make landfalls in Shanghai (SHLD), in the north of Zhejiang (ZNLD) and moving northwards in the offshore area of Shanghai (MNS) under those scenarios. The model results provided assessment of impact of single and compound effects of the three factors (SLR, LS and BC) on coastal flooding in Shanghai for the next few decades. Model simulation showed that by the year 2030, the magnitude of storm flooding will increase due to the environmental changes defined by SLR, LS, and BC. Particularly, the compound scenario of the three factors will generate coastal floods that are 3.1, 2.7, and 1.9 times greater than the single factor change scenarios by, respectively, SLR, LS, and BC. Even more drastically, in 2050, the compound impact of the three factors would be 8.5, 7.5, and 23.4 times of the single factors. It indicates that the impact of environmental changes is not simple addition of the effects from individual factors, but rather multiple times greater of that when the projection time is longer. We also found for short-term scenarios, the bathymetry change is the most important factor for the changes in coastal flooding; and for long-term scenarios, sea level rise and land subsidence are the major factors that coastal flood prevention and management should address.