The impact of Short Rotation Coppice cultivation on groundwater recharge - a spatial (planning) perspective

Abstract

The potential impact of willow/poplar SRC on groundwater recharge (GWR) of arable land is an important issue for spatial environmental assessments. The approach presented in this study aims at an impact assessment for regional planning purposes. Based on a linear regression of annual precipitation to actual evapotranspiration (V ET ), an upper L h (r² = 0.89) and lower L l (r² = 0.74) boundary of annual SRC water use was determined. The impact assessment made use of public available data on land cover (ATKIS) soil properties (BUK50) and regional climate (precipitation grids). The methodology refers to well established rule-sets applied to the soil information system of Lower Saxony, Germany (NIBIS). Results are presented for two municipalities in the district of Uelzen, Northern Germany. The study area is characterized by sandy soils, a low groundwater table and precipitation ranging from 607 to 777 mm a -1 . V ET calculated for the study area ranges from 560 to 714 mm a -1 for (L h ) and from 488 to 544 mm a -1 for (L l ), respectively. For (L h ), calculations show a water deficit for large areas during the vegetation period (1.4. to 31.10). Compared to current agricultural land use, GWR of L h substantially decreases by about 70 %. In case of (L l ), GWR is reduced by about 5 to 10 % compared to current agricultural land use. Thus, from the perspective of ground water protection the focus should be on SRC systems representing (L l ) conditions. The underlying data indicate that willow (poplar) SRC with 2 to 4 year rotation period is typical for (L l ) conditions. There is, however, considerable uncertainty and an urgent need to improve the data base. Representing (L l ) conditions, SRC could be an interesting land use option due to its potential positive impact on soil erosion groundwater quality and landscape structure.