hydrology

Usually the climatic water balance of the site is clearly positive, the period from November to April can be seen as a typical drainage period. Most of the area of the experimental site for irrigation and solar technology is located outside the flood area, only the lowest terrace can be attributed to the recent floodplain. The flood of 1909 reached 135.5 meters above sea level. The investigated profiles are about 0.8m (Profile PG3) to 2.2m (Profile PG 1) higher. It can be assumed that the profile be 1 to 3 have not been flooded since about 150 - 200 years due to the accelerated deepening of the Werra by straightening measures in the 19th century. Nevertheless, it is likely that the groundwater level still occasionally rises while Werra-floods and when side slope water flows into the subfloor. During the investigation period (April-October), the water table was deeper than 2m, so that there is no capillary mobilization from the ground during the growing season into the root zone of annual crops and grassland. After summer rainfall the lateral influx of weak tensioned soil water (interflow) in backwater conductive horizons imay be possible due to the lower slope position (HOSCH et al. 1994). A possible inflow of surface water is nowadays captured by the street sewer. Overall, the site can be classified as moderately protected shadowhillside. After 1966 the water conditions may have changed significantly during the 20 years of intensive irrigation demonstrations at the area . For this time high leaching rates and frequent summer water saturation of the profiles can be assumed. The source for the irrigation water is a well 70 m distant from the Werra, whose high ion concentration probably is influenced by Werra water (bank filtrate).