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An overview presenting some of our activities related to; 1.Hydrology in small agricultural catchments; pathways and their impact on nutrient and soil.

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Presentation on theme: "An overview presenting some of our activities related to; 1.Hydrology in small agricultural catchments; pathways and their impact on nutrient and soil."— Presentation transcript:

1 An overview presenting some of our activities related to; 1.Hydrology in small agricultural catchments; pathways and their impact on nutrient and soil loss. 2.Water sampling 3.Winter and climate change 4.Other issues

2 Analysis on runoff from agricultural dominated catchment Effects of subsurface drainage systems on hydrology/runoff and nutrient loss The effect of time resolution on the hydrological characters The effect of scale on hydrological characters.

3 Location of catchments Catchment are located in Norway (Mørdre, Skuterud, Høgfoss, Lena), Estonia (Rägina, Räpu) and Latvia (Mellupite) All catchments except Høgfoss and Lena are part of National Agricultural Environmental Monitoring Programmes. Quantifying runoff, nutrient and soil loss

4 Catchment monitoring calculation of load Discharge measurement using Crump weir, V- notch Water sampling and analysis(TDS, N tot, P tot ) runoff(mm) N,P,SS loss (kg.ha -1 )

5 Flat V – weir (modifisert Crump)

6 Construction on crest Crump weir

7 Skuterud, oppstuvning?

8 Skuterud backwater

9 Winter, what now

10 Heating of station

11 Flumes H flume

12 tipping bucket as discharge measurement4 structure

13 Point samples strategies. In general, point sampling routines can be divided into three categories, i.e. –point sampling with variable time intervall –point sampling with fixed time intervall –volume proportional point sampling.

14 Different ways to calculate load when grab sampling Load(T) = conc(c) x volume in period (V))

15 Composite volume proportional sampling An alternative to point sampling systems is volume proportional water samples. In this case a small water sample is taken each time a preset volume of water has passed the monitoring station. The sub-samples are collected and stored into one container for subsequent analysis. This composite sample then represents the average concentration of the runoff water over the sampling period. A prerequisite is the availability of a head-discharge relation for the location of the measurement station + datalogger

16 Vannprøvetaking/stofftap

17 in which Ltotal load during sample period C concentration in composite sample for time period t=1 to t=n qt hourly discharge at time t n number of hours represented by the composite sample period Volume proportional sampling

18 Vannprøvetaking/stofftap Sampling systems might be combined so as best to suit its purpose. It is assumed that the chemical concentration of runoff water during low flow periods in a way can be considered constant as long as agricultural runoff is concerned. For low flow periods, a point sampling system with fixed time interval can be implemented, combined with a flow proportional point sampling system for high flow periods.

19 Vannprøvetaking/stofftap Short-term variability in NO3-N concentrations in Høyjord October 6-9, 1995

20 Vannprøvetaking/stofftap Phosphorus dynamics in a typical small agricultural stream (Timebekken, 1.1 km2)

21 Characteristics

22 Runoff and nutrient loss

23 Characteristic for runoff generation is strong seasonality in runoff Catchment Winter Dec - Feb Spring Mar - Apr Summer May - Aug Autumn Sept - Nov Høgfoss Skuterud, Räpu (Est.) Rägina (Est.) Mellupite catchment (Lat.) Mørdre Skuterud, Kolstad During growing season very little runoff

24 Yearly runoff and nutrient loss is generated in only limited number of days runoffSSTPTN %days An example for the Skuterud catchment, Norway (4.5 km 2 )

25 Runoff and nutrient loss in a large catchment runoffTNTP %days Lena catchment (181 km 2 ) runoffTPTN %days Skuterud catchment

26 Characteristic for many catchments is the large in-day variation in discharge

27 Flow characteristics of catchments 1 – specific discharge (l s -1 ha -1 ); In small Norwegian catchments, yearly discharge shows a high variation, is extremely outlier prone. Specific discharge, calculated on average daily and hourly discharge values respectively for Skuterud(4.5 km^2) and Høgfoss(300 km^2) spec. disch 1 coeff. var. catchmentdayhrdayhr Skuterud Mørdre Kolstad spec. disch 1 coeff. var. catchmentdayhrdayhr Skuterud Mørdre Kolstad Høgfoss Lena This is much less pronounced in the large catchments spec. disch 1 coeff. var. catchmentdayhrdayhr Räpu Rägina Mellupite Skuterud Mørdre Kolstad Høgfoss Lena Latvian and Estonian catchments show less variation

28 Winter runoff (Øygarden, 2000) January 30 Runoff: 25 mm Soil loss: 2 kg ha - 1 January 31 Runoff: 77 mm Soil loss: kg ha -1 Winter/snowmelt

29 Runoff generation caused by freeze/thaw cycles in combination with snowmelt/precipitation

30 Variation in discharge can be expressed through a flashiness index, showing the rate of change day; hour (in- day variation); Which factors influence runoff generation?

31 Runoff generation, scale and subsurface drainage Subs dr. 1.The size of the catchment is important and share of agr. land. 2.Subsurface drainage systems seem to have a significant influence on runoff generation

32 The effects of subsurface drainage and nutrient – and soil loss Vandsemb, surfacesubsurface. N-loss (kg/ha) 222 P-loss (kg/ha) SS(kg/ha) Runoff (mm) Bye, surfacesubsurface N-loss (kg/ha) P-loss (kg/ha) SS(kg/ha) Runoff (mm) groundwater level drain Drain spacing, L = 8 – 10 m Drain depth, d = 0.8 – 1.0 m bss.

33 Soil types important Macropore/preferential flow Fast transport to subsurface drainage systems Transporting soil particles/phosphorus? Skuterud, N_loss (kg/ha)45 P_loss (kg/ha)2 SS(kg/ha)1190 Avrenning (mm)504

34 Base flow index Has been calculated using the smooth minima technique (Gustard et al, 1992) Input average daily discharge values No programs available to calculate on hourly discharge values Digital filter is looked at (Chapman, Eckhard). Q t – total runoff Q d – direct runoff

35 Flashiness and base flow index

36 Some conclusions and challenge Norwegian small agricultural catchments show higher variation in discharge compared to those in Estonian and Latvia Factors playing a role seem to be –Subsurface drainage systems –The size of catchment –Share of the agricultural land Time resolution seems to play an important role, small catchment -> high resolution data important Challenge to calculate baseflow on hourly values Only when we have models which simulate the dominating flow generating processes and there affect on nutrient and soil loss under our prevailing climatic conditions we can be successful in implementing the WFD

37 Do we have models to deal with those situations Several models are testet in a Norwegian catchment SWAT (water balance, nutrient and soil loss) –The SWAT model has also been applied in Norway as part of EuroHarp and Striver, two EU – projects (large scale) –The model is tested now in Skuterud DRAINMOD, developed at NCSU (Skaggs) simulating subsurface drainage/surface runoff/nitrogen dynamics HBV – model (hydrology) INCA – model (hydrology, nutrient dynamics) SOIL/SOIL_NO and COUP (hydrology,nitrogen); have been tested (developed by SLU) WEPP (Water erosion prediction model) tested on small plots

38 IS ice too cold for non – Scandinavian models Johannes Deelstra and Sigrun H. Kværnø Based partly on a presentation we had focussing on the winter season and nutrient and soil loss during that period, results of EuroHarp project (EU)

39 What is so special with a winter The winter is the coldest season of the year and for most meteorological purposes is taken to include December, January, and February in the Northern Hemisphere. Air temperatures below 0 o C Precipitation as snow Water turns into ice Slippery roads, traffic problems, accidents

40 Characteristics of Nordic winter Winter season - the time period between the first and last day with an average daily temperature below zero. Often characterised by several freeze/thaw cycles

41 Infiltration and frozen soils, is there any, and how to measure Skuterud catchment 2001/2002 TDR equipment liquid water content Neutron scattering total water content

42 Infiltration and frozen soils, is there any, and how to measure Skuterud catchment 2001/2002

43 Infiltration and frozen soils, is there any and how to measure Infiltration tests in frozen soils, Vandsemb catchment (2002) Excavation in May 2002

44 Infiltration and frozen soils, is there any and how to measure Infiltration tests in frozen soils, Vandsemb catchment (2002)

45 Infiltration and frozen soils ―>latent heat of freezing Water, when freezing releases heat, latent heat of freezing. This know property is used in frost protection The effects of not including the latent heat of freezing in the simulation leads to errors in simulated frost depth.

46 The effect of latent heat on soil frost development Season Season

47 The effect of snow on soil frost development Season Season

48 The effects of freeze/thaw cycles on aggregate stability Reduction: –Clay: 25 % after 6 cycles –Silt: 50 % after 1 cycle  more frequent alterations between mild and cold periods can be expected to increase the erosion risk  erosion risk is higher on silt than on clay

49 The effects of freeze/thaw cycles on shear strength Reduction: 25 % after 6 cycles  Erosion risk increases under unstable winter conditions  Wet soils particularly vulnerable

50 Freeze/thaw and runoff generation

51 Freeze/thaw and runoff generation (Øygarden, 2000) January 30 Runoff: 25 mm Soil loss: 2 kg ha - 1 January 31 Runoff: 77 mm Soil loss: kg ha -1

52 Effect of freeze-thawing on P release from plants (M. Bechmann)

53 Freezing period At one stage during the winter season a prolonged period starts with below – zero temperature But even freezing periods are characterised by several freeze/thaw periods

54 Freezing period In cold regions, the freezing index is among others used to predict the depth of frost penetration The development of frozen soils is influenced by factors such soil moisture condition at the onset of freezing, snow cover, soil type and soil cover.

55 Variation in freezing index Variation in freeze/thaw cycles

56 Measurement results on runoff and nutrient losses from 4 small agricultural catchments in Lithuania, Finland, Sweden and Norway Johannes Deelstra, Sigrun H. Kværnø, Kirsti Granlund, Antanas Sigitas Sileika, Kazimieras Gaigalis, Antanas S. Sileika, Katarinana Kyllmar, Nils Vagstad

57 Some results Nitrogen N loss occurs during the freezing period LöytäneenojaGraisupisSkuterudM36 N loss freez. per.4.9 (35 %)4.5 (33 %)8.7 (20 %)1.4 (5 %) N loss year

58 Some results Phosphorus loss during freezing period LöytäneenojaGraisupisSkuterudM36 P loss fr. period0.1 (20 %)0.1 (33 %)0.5 (20 %)0.01 (3 %) P loss year

59 Is ice then too cold?  If not taken into account the right processes.  Freez/thaw cycles – aggregate stability change usle, rusle, musle, wepp, eurosem,  Infiltration Latent heat of freezing, Change over time in infiltration capacity Effects of snow (Coup, soil, shaw)

60 Winter processes affect the hydrology in large areas of Europe!

61  USLE – regression model, no winter  USLENO – calibrated USLE to Norwegian climate  RUSLE – revised USLE, K – factor adj. according to freeze/thaw cycles  CREAMS – process based model; hydrology, erosion (ULSE factors) and chemistry (nutrients and pesticides)  GLEAMS – improved winter hydrology  ICECREAMS – modified CREAMS, Finnish version  SWAT – winter hydrology, uses modified USLE (MUSLE)  ERONOR – hydrology simulated by SOIL model, uses USLE based factors  EUROSEM – process based model, no winter hydrology routine  EROSION-3D – winter hydrology routine under development  WEPP – winter hydrology routine (under review and testing)

62 Takk for oppmerksomhet


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