Slide 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 Slide 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. Slide 3 Location of catchments Catchment are located in Norway (Mrdre, Skuterud, Hgfoss, Lena), Estonia (Rgina, Rpu) and Latvia (Mellupite) All catchments except Hgfoss and Lena are part of National Agricultural Environmental Monitoring Programmes. Quantifying runoff, nutrient and soil loss Slide 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 ) Slide 5 Flat V weir (modifisert Crump) Slide 6 Construction on crest Crump weir Slide 7 Skuterud, oppstuvning? Slide 8 Skuterud backwater Slide 9 Winter, what now Slide 10 Heating of station Slide 11 Flumes http://www.uwsp.edu/cnr/watersheds/GradStudents/Freihoefer.htm http://info1.ma.slu.se/IM/images/RW1.jpg H flume Slide 12 tipping bucket as discharge measurement4 structure Slide 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. Slide 14 Different ways to calculate load when grab sampling Load(T) = conc(c) x volume in period (V)) Slide 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 Slide 16 Vannprvetaking/stofftap Slide 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 Slide 18 Vannprvetaking/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. Slide 19 Vannprvetaking/stofftap Short-term variability in NO3-N concentrations in Hyjord October 6-9, 1995 Slide 20 Vannprvetaking/stofftap Phosphorus dynamics in a typical small agricultural stream (Timebekken, 1.1 km2) Slide 21 Characteristics Slide 22 Runoff and nutrient loss Slide 23 Characteristic for runoff generation is strong seasonality in runoff Catchment Winter Dec - Feb Spring Mar - Apr Summer May - Aug Autumn Sept - Nov Hgfoss0.300.250.170.28 Skuterud,0.280.270.130.33 Rpu (Est.)0.350.360.15 Rgina (Est.)0.320.310.160.21 Mellupite catchment (Lat.)0.490.240.070.21 Mrdre0.230.350.160.26 Skuterud,0.280.270.130.33 Kolstad0.100.410.230.25 During growing season very little runoff Slide 24 Yearly runoff and nutrient loss is generated in only limited number of days runoffSSTPTN %days 5026121623 901186680106 100365 An example for the Skuterud catchment, Norway (4.5 km 2 ) Slide 25 Runoff and nutrient loss in a large catchment runoffTNTP %days 5038 24 90174166132 100365 Lena catchment (181 km 2 ) runoffTPTN %days 50261623 9011880106 100365 Skuterud catchment Slide 26 Characteristic for many catchments is the large in-day variation in discharge Slide 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 Hgfoss(300 km^2) spec. disch 1 coeff. var. catchmentdayhrdayhr Skuterud2.95.7209239 Mrdre1.72.8222245 Kolstad1.42.4182195 spec. disch 1 coeff. var. catchmentdayhrdayhr Skuterud2.95.7209239 Mrdre1.72.8222245 Kolstad1.42.4182195 Hgfoss1.31.5123125 Lena1.31.5120123 This is much less pronounced in the large catchments spec. disch 1 coeff. var. catchmentdayhrdayhr Rpu0.60.7133135 Rgina0.40.5121122 Mellupite11.2182188 Skuterud2.95.7209239 Mrdre1.72.8222245 Kolstad1.42.4182195 Hgfoss1.31.5123125 Lena1.31.5120123 Latvian and Estonian catchments show less variation Slide 28 Winter runoff (ygarden, 2000) January 30 Runoff: 25 mm Soil loss: 2 kg ha - 1 January 31 Runoff: 77 mm Soil loss: 3 050 kg ha -1 Winter/snowmelt Slide 29 Runoff generation caused by freeze/thaw cycles in combination with snowmelt/precipitation Slide 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? Slide 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 Slide 32 The effects of subsurface drainage and nutrient and soil loss Vandsemb, 1992 - 2004surfacesubsurface. N-loss (kg/ha) 222 P-loss (kg/ha) 0.60.5 SS(kg/ha) 47090 Runoff (mm) 126202 Bye, 1994 - 2007surfacesubsurface N-loss (kg/ha) 1.129 P-loss (kg/ha) 0.30.04 SS(kg/ha) 22020 Runoff (mm) 14165 groundwater level drain Drain spacing, L = 8 10 m Drain depth, d = 0.8 1.0 m bss. Slide 33 Soil types important Macropore/preferential flow Fast transport to subsurface drainage systems Transporting soil particles/phosphorus? Skuterud, 1994 - 2006 N_loss (kg/ha)45 P_loss (kg/ha)2 SS(kg/ha)1190 Avrenning (mm)504 Slide 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 Slide 35 Flashiness and base flow index Slide 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 Slide 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 Slide 38 IS ice too cold for non Scandinavian models Johannes Deelstra and Sigrun H. Kvrn 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) Slide 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 Slide 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 Slide 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 Slide 42 Infiltration and frozen soils, is there any, and how to measure Skuterud catchment 2001/2002 Slide 43 Infiltration and frozen soils, is there any and how to measure Infiltration tests in frozen soils, Vandsemb catchment (2002) Excavation in May 2002 Slide 44 Infiltration and frozen soils, is there any and how to measure Infiltration tests in frozen soils, Vandsemb catchment (2002) Slide 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. Slide 46 The effect of latent heat on soil frost development Season 2000 - 2001 Season 2002 - 2003 Slide 47 The effect of snow on soil frost development Season 2002 - 2003 Season 2000 - 2001 Slide 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 Slide 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 Slide 50 Freeze/thaw and runoff generation Slide 51 Freeze/thaw and runoff generation (ygarden, 2000) January 30 Runoff: 25 mm Soil loss: 2 kg ha - 1 January 31 Runoff: 77 mm Soil loss: 3 050 kg ha -1 Slide 52 Effect of freeze-thawing on P release from plants (M. Bechmann) Slide 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 Slide 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. Slide 55 Variation in freezing index Variation in freeze/thaw cycles Slide 56 Measurement results on runoff and nutrient losses from 4 small agricultural catchments in Lithuania, Finland, Sweden and Norway Johannes Deelstra, Sigrun H. Kvrn, Kirsti Granlund, Antanas Sigitas Sileika, Kazimieras Gaigalis, Antanas S. Sileika, Katarinana Kyllmar, Nils Vagstad Slide 57 Some results Nitrogen N loss occurs during the freezing period LytneenojaGraisupisSkuterudM36 N loss freez. per.4.9 (35 %)4.5 (33 %)8.7 (20 %)1.4 (5 %) N loss year13.913.545.325.6 Slide 58 Some results Phosphorus loss during freezing period LytneenojaGraisupisSkuterudM36 P loss fr. period0.1 (20 %)0.1 (33 %)0.5 (20 %)0.01 (3 %) P loss year0.50.32.40.3 Slide 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) Slide 60 Winter processes affect the hydrology in large areas of Europe! Slide 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) Slide 62 Takk for oppmerksomhet