Post on 11-Jan-2016
description
Land use effect on nutrient loading – nutrient models new assessment tools
Inese Huttunen, Markus Huttunen and Bertel Vehviläinen
Finnish Environment Institute
Basic structure of WSFS-Vemala
Hydrological WSFS-model:• Inputs daily precipitation and temperature• Simulates hydrological cycle on daily time step• Covers all Finland, 6200 sub-basins, 58 000 lakes• Simulated daily• Data-assimilation, ensemble forecasts
Water quality simulation with Vemala• Diffuse loading (agriculture and non-agriculture)• Point load, settlements, atmospheric deposition• Simulates transport in rivers and lakes• Total phosphorus, total nitrogen, suspended solids,
organic carbon (TOC)
Relationship between concentration and runoff / use of VIHMA annual loads
• Runoff r (= r1+r2+r3+r4+r5) is divided into 5 classes rx,
each class has Ptot concentration cx,x which is calibrated• r1: runoff in runoff class 1, 0-1 mm/day• r2 runoff in runoff class 2, 1-3 mm/day• r3 runoff in runoff class 3, 3-6 mm/day• r4 runoff in runoff class 4, 6-10 mm/day• r5 runoff (unlimited) in runoff class 5, > 10 mm/day
• Concentration relationship with runoff
Example of concentration runoff relationship for one out of four seasons
0
200
400
600
800
1000
1200
1400
1600
1800
0 5 10 15 20 25
Runoff, mm
Co
ncen
trati
on
, m
ikro
g/l
Agriculture
Non-agriculture
Total concentration
rcrcrcrcrcr
cx5544332211
VIHMA tool (Puustinen, SYKE) is used to simulate annual agricultural load and Vemala load is adjust
1 100 000 field plots are simulated separately by knowing slope, plant, soil type, P soil
Nutrient balance in lakes
rAVccQtIdtdm
out )(Inflow loading
Outflowingload
Sedimentation
Internal
load
Accumulation = Loading – outflow – sedimentation + internal loading
Annual Phosphorus balance for Karhijärvi
Inflow loading 10.2 t
Outflow load 8.9 t
Sedimentation 5.9 t Internal loading
3.2 t
Calibration
Calibration is the process of modifying the parameters to a model until the difference between output from the model and observed data sets is minimum
Optimization criteria is:
all observation points located at the same calibration area are taken into calibration:• + there is a need to use all available
observations in the calibration even if the are very infrequent (few times per year),
• − more frequently observed points gets more weight in the calibration procedure.
appropriate weights for each type of observations are found and tested to reach the best possible calibration result
Water quality observations are not daily
wq wqn
i
n
isimobssimobs iloadiloadwiconciconcwOC
1 1
22 21
Phosphorus concentration
Phosphorus load
Agricultural load 59% of the total loading into Archipelago Sea
59%
28%
10%
3%
Phosphorus load to Archipelago Sea, 329 t/year
Agriculture, 195 t
Non-agriculture, 91 t
Scattered settlements, 33 t
Point load, 9t
Use of VEMALA to simulate different scenarios
Vemala can be used to simulated present situation
We can change present loadings and simulate concentrations and loadings in the river catchments in changed conditions:
Possible changes are:• Crop management changes by VIHMA / ICECREAM• Wetland effect• Scattered settlement loading changes• Point load changes• Climate change scenarios• Combination of above mentioned
Scenario simulations has been done in TEHO project for Aurajoki, Loimijoki and Eurajoki
Wetland simulation
All possible small ditch catchments with area 20 – 200 ha
Which has at least 20% of agricultural fields
Its possible to simulate the effect of all possible wetlands, we can simulate nutrient sedimentaion in wetland, plant uptake
Present Buffer strips
30% of vegeta-
tion cover in-crease in
winter
50% of vegeta-
tion cover in-crease in
winter
70% of vegeta-
tion cover in-crease in
winter
30% of vegeta-
tion cover in-crease in winter on steeper fields
50% of vegeta-
tion cover in-crease in winter on steeper fields
70% of vegeta-
tion cover in-crease in winter on steeper fields
mannure applica-
tion stoped
double applica-tion of
mannure
P-test values
de-creased
nyky-il-masto
0 -381 0 1177 4561 0 459 4054 -2699 2697 -3016
2010-39
7396 6953 7396 8774 12779 7396 7927 12173 4245 10542 3846
2020-49
11297 10822 11297 12782 17109 11297 11866 16445 7905 14679 7463
2040-69
18708 18173 18708 20389 25289 18708 19347 24547 14865 22541 14354
2070-99
25581 24989 25581 27434 32846 25581 26287 32034 21325 29812 20744
-2500
2500
7500
12500
17500
22500
27500
32500
nykyilmasto2010-39
2020-492040-69
2070-99
TEHO scenarios for Aurajoki, change of Ptot loading from present loading, present loading 60784 kg/year
PT
OT
lo
ad,
kg/y
ear
Scenarios of agricultural practices in TEHO Buffer zones Increase of vegetation cover during the winter (30%, 50%, 70% of
the total agricultural area):• Equally in all catchment• On the steeper sloped fields
Using of mannure decreased by 50% Decresed using of P fertilizer
Conclusions from TEHO scenarios: There is no one single method to reduce agricultural loading,
seceral reduction methods need to be combined The best reduction can be achieved by combination of:
• Increased vegetation cover on fields over 3% slope• Buffer zones are established• Reduced P fertilizer application, that P soil < 14 mg/l• Best management practices of mannure apllication
Summary Agricultural load needs to be reduced to improve the
state of the Baltic Sea Mitigation measures are done on the field scale and
there are needed tools to estimate what is the effect of mitigation measures on the river catchment scale
Nutrient load models (Vemala) can be used to simulate different scenarios how should the agricultural practices be changed to reduce the agricultural loading
There are no one single method to reduce agricultural loading, its a combination of methods
More detailed process description improves the models capability to simulate climate change or agricultural management scenarios
Thank You!
www.environment.fi/waterforecast