1. DIAS INFORMATION DAY GLOBAL WATER RESOURCES AND ENVIRONMENTAL CHANGE Date: 09/07/2004 Research ideas by The Danish Institute of Agricultural Sciences (DIAS) Department of AgroEcology Finn Plauborg Senior Scientist, Ph.D. E-mail: Finn.Plauborg@agrsci.dk

2. DIAS Research ideas founded within: International Research School in Water Resources –www.fiva.dk Announced scolarships –Remote sensing and hydrological modeling –Catchment management at European and national level – an implementation analysis Danish Water Forum – a Danish Partnership on water competence –www.danishwaterforum.dk/

3. DIAS Ideas for this call Global climate change –Changes in the distribution and amount of precipitation Changes in runoff to and recharge from water bodies Changes in evaporation –Changes in wind energy Changes in precipitation corrections –Changes in soil temperatures Changes of C/N turnover in natural and cultivated land Changes in risk of environmental pollution from cultivated land –Environmental change Changes in land use

4. DIAS Ideas for this call Evaporation, precipitation correction factors and modelling at various scales Objectives To combine Earth observations and agro-hydrological modelling to predict the cumulative effects of environmental change and agricultural activities on crop productivity and water resources at the river basin scale. To develop and refine operational methods for calculating total evaporation from different land use types dominating the agricultural landscape, and to examine the validity of precipitation correction factors used in water resource budgets. Emphasis on quantification of the water balance during winter conditions as well as summer conditions.

5. DIAS Ideas for this call Background EU challenge: Maintenance of high crop productivity levels and sufficient good quality water resources in a changing and spatially variable environment. The main environmental concern in Denmark is related to the quality of freshwater resources, severely impacted by intensive agriculture (livestock production). New simulations show that the exploitable groundwater resource has been reduced by 45% since the last national assessment 10 years ago; one important reason being the pollution of shallow groundwater by nitrates and pesticides. Quantifying the water balance of an area involves the estimation of two water budgeting components; the actual evaporation and the true precipitation. Neither assessment is trivial, and significant uncertainties must be expected.

6. DIAS Ideas for this call Background continued Research on precipitation correction factors is dominated by novel Danish work (Allerup and Madsen 1979, Vejen et al. 1998). The most recent correction factors differ from earlier published corrections, mainly in ascribing larger corrections to winter precipitation. What are the potential problems in using such corrections for locations other than those for which they were developed? Uncertainties associated with the assessment of actual total evaporation are ~10% on an annual basis. Several aspects of evaporation from crops are not well known, e.g.: Changes in agricultural land use towards new dominating crops (grass- clover, fodder-maize); the uncertainty related to evaporation from crops receiving less irrigation compared to earlier practice; and the uncertainty related to crop root depth in different agricultural soils.

7. DIAS Ideas for this call Methodology Supersite An agricultural site (‘supersite’) will be equipped to facilitate measurements supporting the analysis and improvement of local and regional water balance estimates. Measurements will focus on the processes of 1) evaporation and photosynthesis 2) precipitation and aquifer recharge (excess precipitation).

8. DIAS Ideas for this call Methodology cont. Modelling of the water balance and crop production The data will support the parameterisation and verification of a SVAT/crop growth model (DAISY). The model will be used at the point/single crop scale to simulate water balance, crop production, nitrogen balance and organic matter transformation. The model will be run in several modes to allow both simple and more physically based methods (Penman-Monteith and Shuttleworth-Wallace) for estimating total evaporation from a cropped surface. Modelling will finally include the application of the distributed DAISY- MikeSHE model to the agricultural site. Earth observations will be used by the model to adjust vegetation properties, including the total harvested N that constitutes the major component of the N budget.