367-5 Predicting Forest Soil Hydraulic Properties for Hydrological Modeling Using Digital Soil Mapping and Existing Soil Data.
See more from this Division: SSSA Division: Forest, Range and Wildland Soils
See more from this Session: Symposium--Digital Soil Mapping of Forest Soil Properties
Abstract:
Saturated hydraulic conductivity (Ksat) is one of the most important soil hydraulic property model inputs as it controls the rate of soil water movement with direct impacts on stream flow. Field measurements of Ksat are expensive with highly variable results mostly due to preferential flow. In this study we combined field measured Ksat at point, hillslope and small catchment scales with digital soil mapping techniques and existing soil data to generate continuous inputs for DHSVM to predict stream flow for a HUC12 watershed. The study site is located in southern Indiana and is part of Crawford Upland physiographic sub region of high relief bedrock hills with slopes varying from 2 to 60%. The watershed was once dominated by native broadleaf forest which currently occupies only 1/3 occurring mostly on steep slopes with the remaining 2/3 divided between permanent pasture on broad flat summits and croplands in valleys and floodplains. The DHSVM captured hydrograph rise, peaks and falling limbs for the majority of precipitation events. Daily hydrographs of observed and simulated stream discharge showed a good performance as indicated by the Nash-Sutcliffe (N-S) overall model efficiency of 0.52 without any model calibration. However, the N-S varied from 0.32 during dry season to 0.72 for winter season due to the variability in soil moisture deficit and evapotranspiration. The results demonstrate the utility of combining DSM techniques with field measurements and existing soil information in improving streamflow predictions that could be used for flood forecast and mitigation.
See more from this Division: SSSA Division: Forest, Range and Wildland Soils
See more from this Session: Symposium--Digital Soil Mapping of Forest Soil Properties