Twinning water quality modelling in Latvia Helene Ejhed, Kickoff meeting Twinning on development of modelling capacity to support water quality monitoring in Latvia Overview of available water quality models Photo Lake Övre hammardammen, Fredrik Ejhed

Twinning water quality modelling in Latvia Helene Ejhed, Overview water quality models - selection  Eutrophication and acidification are well known problems  Water flow and pathways models are numerous  Nutrients N and P have been extensively investigated and models tested  EUROHARP project provides model test results  Water quality models are often chains of submodels  Priority substances WFD annex X often unknown transport pathways and fate

Twinning water quality modelling in Latvia Helene Ejhed, Euroharp project Towards european harmonised procedures for quantification of nutrient losses from diffuse sources  All 9 models applied in 3 country catchments  By lottery applied in 3 additional country catchments  Susve in Lithuania modelled with MONERIS, REALTA, SA and NOPOLU  Nationally used models for international report obligations

Twinning water quality modelling in Latvia Helene Ejhed, Processes of water quality Transport and retention and source apportionment leakage of nutrients from landuse hydrology and flow pathways denitrification processes biota cycling, sedimentation source apportionment point source contributions

Twinning water quality modelling in Latvia Helene Ejhed, Simple balance model within EUROHARP  ”SA” Source apportionment – follows the procedure by HARP-NUT guidelines –Agricultural load is determined only by subtraction of other sources (including retention and background load) from monitored and unmonitored river load on the sea. –The empirical retention models for lakes require only the hydraulic loading, water temperature, N and P loading and an estimate of the P pool in lakes.

Twinning water quality modelling in Latvia Helene Ejhed, Hydrology and flow pathways  Hydrological descriptions are very important for pollution load calculations  Only 4 EH models include hydrological module ANIMO, SWAT, HBV (TRK), EveNFlow –Topography, landuse and soil type divide each basin into hydrological response units HRU (ANIMO, SWAT) or subbasins (HBV) or response groups (EveNFlow) –Daily climate data are drive data –Major differences in snow routines, surface runoff descriptions and how water balance is calculated  SCS (Soil Concervation Service) model –calculates using flow transport factors dependent on landuse and soil type. Snow routine and monitored baseflow can be added. Daily data.

Twinning water quality modelling in Latvia Helene Ejhed, Hydrology example results Top graph shows model flow results vs monitored data. Low graph shows model transport total N results vs monitored data. TRK (HBV hydrology) model

Twinning water quality modelling in Latvia Helene Ejhed, Diffuse sources models - agricultural contributions  Empirical models –For example regression analysis of most important factors for N and P transport –Ex. EH models REALTA and NOPOLU. –Limited possibilities to scenario calculations  Process based models with a high resolution are mainly developed to evaluate the effects of agricultural management practices or detailed (sub-)catchment management. –Ex. EH models SWAT, NL-CAT (ANIMO), TRK(SOILNDB) –Input data heavy –Expert user

Twinning water quality modelling in Latvia Helene Ejhed, Ex. Animo –fertilization level, soil management to nutrient leakage

Twinning water quality modelling in Latvia Helene Ejhed, Ex SOILNDB –calculates standard N leaching rates from combinations of soils,crops, normal yield, normal climate per region

Twinning water quality modelling in Latvia Helene Ejhed, Retention models  Retention – recycling within the freshwater ecosystem  Biota exchange, sediment exchange, atmospheric exchange and lake compartments exchange etc.  EUROHARP-RETNUT –Retention capacity derived empirically

Twinning water quality modelling in Latvia Helene Ejhed, Application for scenario analysis  Only few of EUROHARP models were considered suitable for scenario analysis (predicting effects of measures) –MONERIS, NL-CAT(ANIMO), SWAT, TRK (SOILNDB) –But MONERIS cannot be used for water measures

Twinning water quality modelling in Latvia Helene Ejhed, Watshman PC tool Data management, pollution flow, source distribution and action/investment scenarios

Twinning water quality modelling in Latvia Helene Ejhed, Data management and presentation options as selecting, editing, simple calculations and usual GIS functions. ArcHydro connections under development. - Nutrient transport options with chains of models as diffuse leakage, lake retention model etc. - Scenario management options as changes in crop, landuse, sewage treatment etc.

Twinning water quality modelling in Latvia Helene Ejhed, Results for Lithuania Susve river catchment  MONERIS performed well –difficulties in DIN peak year –Susve 34 % N retention and 66 % P retention  REALTA only calculates risc  NOPOLU no results yet

Twinning water quality modelling in Latvia Helene Ejhed, Proposal to approach in Latvian application  WFD demands –Typology –Reference conditions –Characterisation –Pressures –Measures  Get a quick overview using simple balance calculations if data are available  Identify problem issues, ex. eutrophication acidification, other pollutants, hydrological issues resolution etc.  Identify important processes, ex. snow routines, flooding, sediment transport, wetland and lake processes etc. to apply the right models.  Use combinations of well known models tested from similar areas.