# Presentation: 170359

## The global hydrologic cycle

- Ground water, surface water, soil moisture, snow pack, glaciers, ocean, atmosphere

## Grand Challenges in Hydrology

- The terrestrial hydrologic cycle:
- Ground water, surface water, soil moisture, snow pack, glaciers (see Cryosphere)
- What are the contributions of each land component to the global fresh water budget?
- How do natural and anthropogenic processes redistribute water in both space and time?
- How can we manage the water resources, mitigate associated hazards and integrate decision support?
- How does the land surface vary with time and how does it influence the dynamic water supply?

## Ground Water

- Regional and continental scale aquifer characterization
- Structural control - i.e. ground water barriers
- Storage coefficients/parameters (flux and storage)
- Subsidence mapping and hazard mitigation
- Spatial, temporal, & magnitude control on land subsidence
- Includes hydrocarbon and methane (CBM)
- Earth fissuring - horizontal motion
- Hydro-tectonics
- Separating anthropogenic and tectonic subsidence sources
- Aquifer poro-elastic response to earthquakes
- Liquefaction
- Groundwater management
- Aquifer storage and recovery
- Subsidence mitigation

*J. Hoffmann, 2003 *

## Ground Water

- Regional and continental scale aquifer characterization
- ECHO – L-band InSAR mission with sub-monthly acquisitions
- Access to current archives is required to establish long-term trends
- C-band mission compatible with previous system
- Subsidence mapping and hazard mitigation
- ECHO – L-band InSAR mission with semi-monthly acquisitions
- Multi look angles - 3D deformation field
- Access to current archives is required to establish long-term trends
- Hydro-tectonics
- ECHO – L-band InSAR mission with semi-monthly acquisitions
- Multi look angles - 3D deformation field
- Access to current archives is required to establish long-term trends
- Groundwater management
- ECHO – L-band InSAR mission with sub-monthly acquisitions
- Multi look angles - 3D deformation field
- Access to current archives is required to establish long-term trends

## Surface Water

- Global time-series
- Monitoring of vital spatial & temporal changes in surface water resources through aerial extent and volume measurements
- Resolving velocity and circulation patterns in rivers and water bodies
- Flood, Inundation, and Hazard Assessment
- All weather tool for monitoring surface water extent during events
- Spatial & temporal control on extent, water level, velocity patterns
- Biogeochemical production in tropical areas
- Inundated regions correlated with methane production
- Natural and human oil spills - backscattering properties
- Model and predict ice-debris accumulations,
- 	failure locations, and the resulting flood levels
- Wetland
- Water flow, engineering structures,
- 	water levels, restoration and management

*Wdowinski, et al, 2004*

## Surface Water

- Global time series
- L-Band mission with a minimum 14 day repeat time - daily acquisitions would be ideal.
- Need near-nadir look angles to maximize water body backscattering
- Along-track interferometry for velocity measurements
- VV, HV,VH, HH polarization for vegetation
- Access to current archives is required to establish long-term trends
- Flood, Inundation, and Hazard Assessment
- Multi-band mission desired, minimum L- Band mission with daily to sub-daily acquisitions
- Need near-nadir look angles to maximize water body backscattering
- Along-track interferometry for velocity measurements
- VV, HV,VH, HH polarization for vegetation
- Access to current archives is required to establish long-term trends
- Wetland
- L- and C- Band 5-day interferometric repeat time

## Soil Moisture

- 	*Soil moisture is an essential parameter in measuring the global water budget, climate modeling, and flood, landslide and debris flow forecasting.*
- Detailed 4-D soil moisture maps
- What is the state of the water (permafrost, frozen, liquid, etc)?
- How do natural and anthropogenic processes impact the dynamic soil moisture supply?
- What is the link between ecology, land-use, and soil moisture?
- What is the depth distribution of soil moisture?

## Soil Moisture

- Detailed  4-D soil moisture change maps
- Multi-wavelength capability for varied penetration depths
- Soil moisture as a function of depth
- Minimum depth 10 cm and Maximum depth 1-2 meters
- Full polarization desired
- 10 meter postings desired
- Temporal coverage
- Ideal = daily
- Minimum = weekly

- “This image shows what we believe is drying (blue) and moistening (yellow/red) between two SAR acquisitions in an arid region of Colorado. Pixel size is 50 m and image width is several kilometers.”
*Nolan, 2002*

## Snow Pack

- What is the extent and volume of water in snow pack?
- Resolving the snow-water equivalence is essential for constraining the contribution of the snow pack on the global water budget and forecasting water supply.
- How do snow pack properties vary spatially and temporally?
- Need real-time data collection for flood prediction associated with snow melt.
- Weekly coverage
- Glacial mass balance  (see Cryoshpere)

## Snow Pack

- What is the extent and volume of water in snow pack?
- Satellite requirements
- L-Band minimum
- Multi-wavelength acquisition preferred
- Full polarimetry for snow structure is desirable
- Weekly coverage

*Rott, et al, 2003*

## Land Surface Change

- 	How does the land surface vary with time and how does it influence the dynamic local-global water supply, especially when radar scatters are significantly altered? .... DEM subtraction
- What is the source, path, deposition, and volume of material transported during large events?
- The temporal and spatial SAR imaging will result in significant advances in the understanding of the mechanics, kinematics, monitoring, and prediction of mass movement.
- Hazards include landslides, sink holes, mine collapse, floods
- What is the volume of material lost in coastal erosion?
- What is the relationship between hydrology and habitat in slope stability in post-fire environments?
- How do hydrologic parameters vary with topographic change?

## Land Surface Change

- 	How does the land surface vary with time and how does it influence the dynamic local-global water supply, especially when radar scatters are significantly altered? .... DEM subtraction
- InSAR requirements
- Z  (vertical) relative error of 1/2 meter desired
- X,Y (horizontal) resolution at a minimum of 20 meters
- Orbit/mission control optimized to potentially generate monthly DEMs

- Differential ERS generated DEMs mapped
- Net erosion and deposition caused by an
- Extreme glacier outburst flood in Iceland
- November 1996.
- Smith et al, 2000