MODELING HYDROLOGIC ALTERATIONS TO A DEVELOPING WETLAND IN AN ABANDONED BORROW PIT

Three management alternatives for modifying the duration and extent of pending at a developing wetland in northern Texas, USA, were evaluate d. These alternatives, causing minimal environmental disruption and re quiring little maintenance, included installing a slurry wall to back up groundwater, raising water levels in a nearby river channel and app lying water directly to the wetland. The wetland resides in a topograp hic depression which was created by excavating sediment for an earthen dam. The authors characterised the hydrogeology of the wetland, devis ed a numerical model to simulate groundwater flow and used the model t o study potential hydrologic modifications to the wetland. Evapotransp iration and recharge dominate the water budget of the site. Model-calc ulated hydraulic head values indicated that applying water directly to the wetland elevates the water-table, while installing a downgradient slurry wall and elevating stages of nearby surface wafer bodies have little effect. These results suggest that diverting surface water shou ld be an effective management technique for groundwater-fed wetlands w ith sediment of low to moderate hydraulic conductivity. (C) 1998 Acade mic Press.