#Mike 21 river rainfall flooding manual

MIKE 21 is a comprehensive modelling system used to simulate hydraulics and hydraulic-related phenomena in different bodies of water. Amongst these simulation tools is the commonly used MIKE 21 software. Thus, model simulation techniques are now being increasingly applied to simulate the impacts of these events on both water quantity and quality in many lakes.

#Mike 21 river rainfall flooding manual

However, it is difficult to use real-time monitoring data to explain the impacts of spring freshet and summer rainfall flooding on lake water quality, because of insufficient manual monitoring times and the impact of flood disturbance on automatic monitoring systems. As such, snowmelt or rainfall runoff that moves through inflowing rivers and mountains play important roles in the natural processes associated with barrier lakes.

Alpine barrier lakes are surrounded by mountains. Owing to their special structures, barrier lakes continually interact with their original bodies of water, which are usually large rivers. Spring freshet flooding comes from late spring melts, whilst summer rainfall flooding often occurs in the summer and autumn. In this context, spring freshet and summer rainfall flooding both increase barrier lake instability whilst also impacting water quality. According to previous research, both the frequency and intensity of summer rainfall flooding are increasing in many places because mean global land precipitation has increased due to global warming. Wet precipitation, including snow and rainfall, has the chance to form spring flooding and summer rainfall flooding which flows into the barrier lake via upstream river(s). Usually, barrier lakes and the original rivers have close relationships, and they are more affected by the upstream rivers than other types of lake. Upstream rivers and wet precipitation are the two important natural water supply sources for lakes.

Based on topography and/or the formation process, barrier lakes can be further divided into alpine barrier, lava barrier, and moraine barrier lakes. An example is the Kananaskis barrier lake in Alberta, Canada. Some barrier lakes have been anthropogenically created on large rivers to generate hydroelectric power. River interception events may obstruct water flow and collect water in valleys or riverbeds. They are formed by river interception which results from events such as volcanic lava flows, earthquake-induced landslides, glaciotectonic disturbance, or anthropogenically activities. In addition to pollution source control measures, ecological restoration, and the construction of a buffer system in the catchment are very important measures to effectively improve the buffer capacity of barrier lakes in light of spring freshet flooding and summer rainfall flooding.Д«arrier lakes attract special attention due to their unique formation process. The sudden increase in water volume during spring flooding and summer rainfall flooding led to the rapid spread of nutrients and pollutants carried by the water into the barrier lake, resulting in a deterioration of lake water quality. A larger amount of precipitation leads to longer diffusion distances and increased concentrations of total nitrogen (TN), total phosphorous (TP), chemical oxygen demand (COD Mn), and ammoniaвЂ“nitrogen (NH 4-N) in the lake. The longest diffusion distances from the lake mouth to the downstream way are 16.3В km, 33.1В km, and 43.6В km during the spring freshet flooding, summer rainfall flooding, and 30-year frequency rainfall flooding period, respectively. The flow volume of its largest inflowing river reaches 4.81вЂ‰Г—вЂ‰10 8В m 3, 29.77вЂ‰Г—вЂ‰10 8В m 3, and 58.4вЂ‰Г—вЂ‰10 8В m 3 during spring freshet flooding, summer rainfall flooding, and 30-year frequency rainfall flooding period, respectively. According to model simulation results, the flow velocity in Lake Jingpo is generally weak (mostly lower than 0.015В m/s), but it increases to 0.045В m/s and above during spring freshet flooding (AprilвЂ“May) and summer rainfall flooding (AugustвЂ“September), which is much higher than in other months. The MIKE 21 HD hydrodynamic model and MIKE 21 AD convection and diffusion module were calibrated using meteorological data, hydrological data, and water quality data collected in 2018. In this study, we used Lake Jingpo, the worldвЂ™s second largest alpine barrier lake, to examine the impact of spring freshet flooding and summer rainfall flooding on its water quality by building a hydrodynamic water quality model with MIKE 21. Too much nutrients will lead to lake eutrophication. snow and rainfall) may sharply increase the concentrations of nitrogen, phosphorous, and carbon compounds in barrier lakes.

As such, spring freshet flooding and summer rainfall flooding due to wet precipitation (e.g. Barrier lakes, formed by river interception, are particularly influenced by the upstream river.