Major River Basins in various climate zones Major River Basins in various climate zones Major River Basins in various climate zones Major River Basins in various climate zones
Modelling Modelling Modelling
Modelling nutrient fluxes using global datasets nutrient fluxes using global datasets nutrient fluxes using global datasets nutrient fluxes using global datasets
– – –
–test on the Rhine Basin test on the Rhine Basin test on the Rhine Basin test on the Rhine Basin
S.
S.
S.
S. Loos Loos Loos Loos, H. , H. , H. Middelkoop , H. Middelkoop Middelkoop, L.P.H. van Middelkoop , L.P.H. van , L.P.H. van , L.P.H. van Beek Beek Beek Beek and and and M. van der Perk and M. van der Perk M. van der Perk M. van der Perk / / / / Dept. of Physical Geography, Utrecht University, The Netherlands Dept. of Physical Geography, Utrecht University, The Netherlands; e Dept. of Physical Geography, Utrecht University, The Netherlands Dept. of Physical Geography, Utrecht University, The Netherlands ; e ; e ; e- - - -mail: mail: mail: mail: s.loos@geo.uu.nl s.loos@geo.uu.nl s.loos@geo.uu.nl s.loos@geo.uu.nl
References
Bergström, S. (1995). The HBV Model. Computer models of watershed hydrology. V. P. Singh. Colorado, Water Resources Publications: 443-476.
De Wit, M.J.M. (2001). Nutrient fluxes at the river basin scale. I: the PolFlow model. Hydrological Processes 15(5): 743-759.
Data Source: IKSR - Internationale Kommission zum Schutz des Rheins, Bundesanstalt für Gewässerkunde, www.iksr.org.
Morgan, R.P.C. (2001). A simple approach to soil loss prediction: a revised Morgan-Morgan-Finney model, Catena 44: 305-322.
Water fluxes
RIVERINE NUTRIENT LOAD RIVERINE NUTRIENT LOAD RIVERINE NUTRIENT LOAD
RIVERINE NUTRIENT LOAD SOURCE APPORTIONMENT SOURCE APPORTIONMENT SOURCE APPORTIONMENT SOURCE APPORTIONMENT
Denitrification
Labile Pool (DIN) Stable Pool (orgN)
Erosion
Quick Runoff Residue
Leaching
Groundwater (NO3)
Delayed GW
Plants/crops (orgN)
/
• Fertilizer
• Manure
• Atm. Deposition
• Volatilisation
•Biological fixation
•Yield
GW
River
(2) Lake (3)
LS (1)
… ±15 cells
QBf Vegetation
Store 1
Store 2
PREC Epot
Eact
QDR
P T
QChannel
PREC Epot
QChannel QSn
QBf Vegetation
Store 1
Store 2
PREC Epot
Eact
QDR
P T
QChannel
PREC Epot
QChannel QSn
Courtesy Rens van Beek
ERA40 climate input
Monthly discharge - Rhine, Lobith
0 1000 2000 3000 4000 5000 6000
Jan'80 Jan'82 Jan'84 Jan'86 Jan'88 Jan'90 Jan'92 Jan'94 Jan'96 Jan'98 Jan'00
m3/s
Q (measured) Q (modelled)
Conclusions
Distributed modelling in large basins enables nutrient apportionment, and helps to allocate areas that attenuate or contribute to the delivery of emitted nutrients.
Nutrient dynamics are closely related to variation in soil water change and temperature variations. Therefore inclusion of seasonality may improve the prediction of future nutrient loads following Global Change (e.g.
climate, landuse).
The RiNUX model, designed for intermediate scale, is able to predict present nutrient dynamics for a temperate, human-dominated river under seasonally variable conditions using globally available datasets and may contribute to predict nutrient delivery to coastal seas.
The incorporation of seasonally variable nutrient fluxes may enhance the modelling of river basins located in other climate regions.
Aim
Develop a model for estimating seasonal nutrient fluxes (N & P) from large river basins to coastal seas using global datasets, that can provide a more accurate estimate of future nutrient loading in response to global change.
MODEL INPUT
Nutrient Emission
Abstract
Nutrient discharge to coastal waters from rivers draining populated areas is often the direct cause of large algal blooms. Changing conditions in the drainage basin, like land use or climate change, can alter current riverine N and P fluxes and further increase the pressure on coastal water quality. Several small and large scale models have been employed to quantify riverine nutrient fluxes on a yearly to decadal timescale. These models are either too detailed for global application or too coarse in temporal resolution for incorporation of seasonal dynamics. A new model, RiNUX, has been developed to adequately simulate present nutrient loads and capture the intra-annual variation at the basin scale using globally available distributed datasets. The model shows that groundwater and point sources are the largest suppliers of N measured at the river outlet. Preliminary results show a Nash- Sutcliffe efficiency of 0.67 for modelled monthly TN loads over the period 1990-2000.
SOIL NUTRIENT TRANSFER:
Surface runoff, groundwater buffer or soil storage
RETENTION IN CHANNEL:
f (Temp,Floodplain,Discharge)
G ro u n d W at er -- -- -- -- -- -- -- -- -- -- S u rf a ce W a te r
test basin: Rhine test basin: Rhine test basin: Rhine test basin: Rhine
Agricultural emission ↑ Point source emission →
Fertilizer application
Nutrients enter the river basin via application of fertilizers and manure, through atmospheric deposition, biological fixation, weathering or sewage and are transfered to the river outlet by water and sediments.
Suspended Sediment Export at Lobith
Sediment fluxes
The transfer of dissolved (in the labile pool) and particulate (in the stable pool) nutrients from the soil to either the surface water or groundwater is dependent on the nutrient content, moisture, temperature and other properties (e.g. texture) of the soil.
MODEL SCHEME
Main tributaries contributing
sediment and associated nutrients.
monthly SS-load, Rees/Lobith
0 300 600 900 1200
Jan'84 Jun'85 Oct'86 Feb'88 Jul'89 Nov'90
measured load (1000t) modelled load (1000t)
Groundwater ‘Buffer’
0.E+00 5.E+05 1.E+06 2.E+06 2.E+06 3.E+06 3.E+06 4.E+06 4.E+06 5.E+06 5.E+06
1973 1976 1979 1982 1985 1988 1991 1994 1997 2000
GW Recharge GW Outflow GW Outflow after denitrification
Retention
k g /k m 2 /y r
Nutrients leaching to the groundwater store are retained based on the residence time before entering surface water. Part is denitrified during transport.
agriculture atmospheric deposition sewage
21%
< 1%
78%
Lobith TN ( load )
0 5 10 15 20 25 30
Oct'89 Oct'90 Oct'91 Oct'92 Oct'93 Oct'94 Oct'95 Oct'96 Oct'97 Oct'98 Oct'99 Oct'00
k g /s .
month - avg (meas) modelled
Nash & Sutcliffe efficiency: E=0.67
Agricultural land:
2·10
3kg N/km
2/yr reaches the river in dissolved form; while only 6 kg N/km
2/yr as particulate N.
Retention:
The summed retention in the groundwater and in the channel amounts to 73% of the nutrients that are mobilized in the soil.
MODEL OUTPUT
Particulate nutrient flux Dissolved nutrient flux Nutrient removal
Climate zones (Holdridge)
Cool Desert, Hot Desert Forest Tundra, Boreal Forest Oceans
Steppe, Chapparal
Temperate Forest, Warm Temperate Forest Tropical Seasonal Forest, Tropical Rain Forest Tropical Semi-Arid, Tropical Dry Forest Tundra / Polar, Cold Parklands
kg N/km2
5.78e5
0
Adapted from RMMF model (MORGAN, 2001)
margin Sub-basin
TC- limited
F
dirF
indH
Ill
Aare Neckar
Main Lahn
Mosel
F= splash erosion H= runoff erosion TC= transport cap.
Elevation [m]
4108
-1
