Disentangling the Contributions of Snow, Frozen Ground, Soil Moisture, and Water Table Fluctuations to GRACE-detected Seasonal TWS Variability in the Delaware River Basin
Abstract
As a direct observation of changes in water storage, information from the GRACE satellite missions are indicators of how regional systems store and release water and are therefore important to a range of regional water availability concerns (e.g., landscape response to drought). However, because GRACE vertically integrates total water storage (TWS) over large spatial extents, regional modeling and monitoring is needed to better understand interactions amongst the multiple water budget components for which the TWS anomaly is an aggregate expression. In this study we examine (i) the climatological controls, (ii) the effects of seasonal soil-water storage cycles, and (iii) the effects of human water use on TWS dynamics in the Delaware River Basin (DRB), USA, in order to characterize the spatially distributed inputs, outputs, and storage capacities. North-to-south (> 400 km) gradients in the DRB include differences in precipitation and temperature (e.g., more snow and longer, deeper frozen ground in the northern headwaters) as well as differences in subsurface and catchment storage properties (e.g., changes in catchment diffusivity). Additional confounding effects on the interpretation of the storage signal in the DRB include transfers out of the basin from headwater reservoirs to New York City as well as public supply withdrawals in lower-basin metropolitan areas (e.g., Philadelphia) and irrigation withdrawals in the agriculturally intensive coastal plain. To disaggregate these components and compare the aggregated storage signals to GRACE, we use a MODFLOW groundwater simulation calibrated against groundwater levels and streamflow, coupled with historic estimates of net recharge and soil water deficits, for 2003-2015. Preliminary results suggest good agreements can be obtained at monthly intervals by treating the soil water deficit as a single budget component. We will additionally report on attempts using SUTRA-ICE to resolve the significance of the seasonal freeze-thaw cycle and its potential to temporarily store water in the vadose zone and thus delay recharge to the water table.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMH064.0006Z
- Keywords:
-
- 1240 Satellite geodesy: results;
- GEODESY AND GRAVITY;
- 1829 Groundwater hydrology;
- HYDROLOGY;
- 1836 Hydrological cycles and budgets;
- HYDROLOGY;
- 1855 Remote sensing;
- HYDROLOGY