start:hype_model_description:hype_np_riv_lake
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start:hype_model_description:hype_np_riv_lake [2018/11/16 15:45] cpers [Basic assumptions] |
start:hype_model_description:hype_np_riv_lake [2020/02/14 11:14] cpers [Primary production and mineralization] |
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| ====== Nitrogen and phosphorus processes in rivers and lakes ====== | ====== Nitrogen and phosphorus processes in rivers and lakes ====== | ||
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| - | ===== Basic assumptions ===== | ||
| HYPE simulates concentration of inorganic nitrogen (IN), organic nitrogen (ON), soluble reactive phosphorus (SP) and particulate phosphorus (PP) in discharge and other surface waters. As output also the total nitrogen (TN) and phosphorus (TP) concentration can be had. In addition total suspended sediments (TS) can be simulated. It consists of the sum of suspended sediments (SS) and algae (AE) simulated concentrations. | HYPE simulates concentration of inorganic nitrogen (IN), organic nitrogen (ON), soluble reactive phosphorus (SP) and particulate phosphorus (PP) in discharge and other surface waters. As output also the total nitrogen (TN) and phosphorus (TP) concentration can be had. In addition total suspended sediments (TS) can be simulated. It consists of the sum of suspended sediments (SS) and algae (AE) simulated concentrations. | ||
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| + | ===== Basic assumptions ===== | ||
| Transformations of nutrients take place in lakes and rivers. For lakes, which are divided into fast (FLP) and slow (SLP) lake parts, the process is performed only in SLP (Fig. 1). For rivers, which hold delayed water in a queue and in the damping box, the processes is performed only in the damping box. | Transformations of nutrients take place in lakes and rivers. For lakes, which are divided into fast (FLP) and slow (SLP) lake parts, the process is performed only in SLP (Fig. 1). For rivers, which hold delayed water in a queue and in the damping box, the processes is performed only in the damping box. | ||
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| ===== Primary production and mineralization ===== | ===== Primary production and mineralization ===== | ||
| - | Primary production in lakes and rivers is a source of organic nitrogen and particulate phosphorus and a sink for inorganic nitrogen and soluble reactive phosphorus in the model. The reverse is true for mineralization. The processes is modelled together and only one is active at the time. Primary production and mineralization are controlled by two temperature functions. The first (//tmpfcn1//) is solely dependent on the water temperature (//T<sub>w</sub>//). It simulates the increased activity at warmer temperatures. The second (//tmpfcn2//) governs the relationship between primary production and mineralization and determines which one dominates. Net primary production is highest in spring (northern hemisphere) and changes into net mineralization when the temperature //T10// is less than the temperature //T20// in autumn. These two temperatures are calculated as the average water temperature of 10 and 20 days. | + | Primary production in lakes and rivers is a source of organic nitrogen and particulate phosphorus and a sink for inorganic nitrogen and soluble reactive phosphorus in the model. The reverse is true for mineralization. The processes are modelled together and only one is active at the time. Primary production and mineralization are controlled by two temperature functions. The first (//tmpfcn1//) is solely dependent on the water temperature (//T<sub>w</sub>//). It simulates the increased activity at warmer temperatures. The second (//tmpfcn2//) governs the relationship between primary production and mineralization and determines which one dominates. Net primary production is highest in spring (northern hemisphere) and changes into net mineralization when the temperature //T10// is less than the temperature //T20// in autumn. These two temperatures are calculated as the average water temperature of 10 and 20 days. |
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| For lakes, the process is acting only in lake part SLP, while the processes are active throughout the watercourse volume. The estimated production/mineralization (//minprodNpot//, kg / day) is the potential transformation, and may be limited by the availability of nutrients. Only 50% of the available IN the pool (at the primary production) or 50% of the ON-pool (for mineralization) can be transformed. The potential phosphorus conversion (//minprodPpot//) is calculated in the same way, but with its own parameter (//wprodp//) and a factor for phosphorus/nitrogen ratio (//NPratio// = 1/7.2). Similarly, there is a restriction against transforming maximum 50% of the SP and PP pools. The parameters //wprodn// and //wprodp// is generic or can be specified for each lake. The area is equal to lake area for lakes and bottom area for rivers (width multiplied by the length of the watercourse). | For lakes, the process is acting only in lake part SLP, while the processes are active throughout the watercourse volume. The estimated production/mineralization (//minprodNpot//, kg / day) is the potential transformation, and may be limited by the availability of nutrients. Only 50% of the available IN the pool (at the primary production) or 50% of the ON-pool (for mineralization) can be transformed. The potential phosphorus conversion (//minprodPpot//) is calculated in the same way, but with its own parameter (//wprodp//) and a factor for phosphorus/nitrogen ratio (//NPratio// = 1/7.2). Similarly, there is a restriction against transforming maximum 50% of the SP and PP pools. The parameters //wprodn// and //wprodp// is generic or can be specified for each lake. The area is equal to lake area for lakes and bottom area for rivers (width multiplied by the length of the watercourse). | ||
| - | <m> minprodNpot = wprodn * TPfcn * tmpfcn * area </m> | + | <m> minprodNpot = wprodn * TPfcn * tmpfcn * area * depth </m> |
| - | <m> minprodPpot = wprodp * TPfcn * tmpfcn * area * NPratio </m> | + | <m> minprodPpot = wprodp * TPfcn * tmpfcn * area * depth * NPratio </m> |
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| For simulations of total suspended sediments, algae is simulated as a component of the suspendend material. Nitrogen in algae is assumed to grow and decline with the same function as production and mineralisation of organic nitrogen. If nitrogen is simulated it uses the actual estimated production/mineralisation, but otherwise the potential production/mineralisation (//minprodNpot//) is used. The mineralisation of algae is limited to available amount, but the production is then unlimited. | For simulations of total suspended sediments, algae is simulated as a component of the suspendend material. Nitrogen in algae is assumed to grow and decline with the same function as production and mineralisation of organic nitrogen. If nitrogen is simulated it uses the actual estimated production/mineralisation, but otherwise the potential production/mineralisation (//minprodNpot//) is used. The mineralisation of algae is limited to available amount, but the production is then unlimited. | ||
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| ===== Sedimentation/Resuspension ===== | ===== Sedimentation/Resuspension ===== | ||
| - | Sedimentation in lakes is a sink for particulate phosphorus (PP) and organic nitrogen (ON), as well as for suspended sediments (SS) and algae (AE). Sedimentation (//sed//, //m/day//) is calculated as a function of concentration (//conc//) in the lake and lake area (//area//). The sedimentation rate (//par<sub>sed</sub>//) is given by parameters (//sedon//, //sedpp//, //sedss//, //sedae//) which are generic, but ON and PP sedimentation can be specified for each lake. The concentration used in the equation may be limited (//lim//) by general parameters (//limsedON//, //limsedPP//, //limsedSS//), but not for AE (//lim//=0). | + | Sedimentation in lakes is a sink for particulate phosphorus (PP) and organic nitrogen (ON), as well as for suspended sediments (SS) and algae (AE). Sedimentation (//sed//, //kg/day//) is calculated as a function of concentration (//conc//) in the lake and lake area (//area//). The sedimentation rate (//par<sub>sed</sub>//) is given by parameters (//sedon//, //sedpp//, //sedss//, //sedae//) which are generic, but ON and PP sedimentation can be specified for each lake. The concentration used in the equation may be limited (//lim//) by general parameters (//limsedON//, //limsedPP//, //limsedSS//), but not for AE (//lim//=0). |
| <m> sed = par_sed * (conc-lim) * area </m> | <m> sed = par_sed * (conc-lim) * area </m> | ||
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