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Violet's Notes
Violet Huang edited this page Jun 29, 2023
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- GRACE is good at measuring ice mass change, more accurate than other methods and gives more temporal resolution (monthly). Measurements in Antarctica are less accurate due to mass-redistribution induced by glacial-isostatic adjustment
- GRACE can be combined with other datasets to infer the factors causing mass loss; relate changes in mass loss with global atmospheric circulation
- GRACE can be used to track continental water mass change, serves as an indicator for climate models, predictor of the growth rate of CO2
- GRACE can be used to identify and estimates groundwater depletion
- GRACE model can be incorporated in climate models and increase early warning lead times
- GRACE can be combined with Argo (ocean hydrographic profiles) to understand global sea-level budget and the source of sea level rise
- GRACE can be combined with Argo (ocean hydrographic profiles) and other datasets to predict deep-ocean warming trends
- GRACE can be used to measure ocean bottom pressure with accuracy and high temporal resolution
- GRACE can be used to more accurately monitor drought by incorporating terrestrial water storage data
- GRACE can be used to increase the lead times of early flood warnings by incorporating soil dryness
- There's a lack of regulatory framework to manage groundwater withdrawals outside of "river aquifer" systems
- Used GRACE data from 2004 to 2013
- GRACE data's accuracy in terms of water storage can be assessed by comparing with the monthly storage changes computed from independent water budget analysis (regional precipitation data from PRISM), satellite-based evapotranspirtion from MODIS, and U.S. Reclamation dam releases accounting for each respective error rates
- Water storage changes are computed as anomalies of terrestrial water storage in equivalent water height (mm, then converted to cubic km using the area of the study basins)
- GRACE-based estimates of groundwater storage changes in Colorado River Basin area can be validated by comparing with monitoring wells located in the area (data from USGS Groundwater Climate Response Network and Arizona Department of Water Respurces)
- CRB area is divided into Upper Basin and Lower Basin when examining water scarcity
- Water losses in the Basin are dominated by the depletion of groundwater storage.
- Drought monitoring requires global perspective: regional variability in the global water cycle induces drought, regional drought has global consequences (food price)
- Current way of drought monitoring: ground-based point observations or interpolated grids primarily from meterological and agricultural perspectives
- Shortcomings of the current way of drought monitoring: globally, many areas used for agricultural production are not well instrumented; the available observations are not sufficient to capture the spatiotemporal variability of drought-related variables such as precipitation; observations from different meteorological stations have different record lengths and data quality
- Drought severity is calculated by calculating the extent of an anomaly from the long-term environmental baseline
- Indicators for drought monitoring that remote sensing can contribute to: meteorological(precipitation, soil moisture, groundwater and terrestrial water storage, evapotranspiration, snow), ecological (vegetation health and land cover) 8 Researchers have developed multi-index drought models
- Changes to groundwater = changes to Terrestrial Water Storage - changes to soil moisture - changes to snow water equivalent
- What can GRACE do:
- monitoring ground water change: timespan is short, may not be sufficient for climatological drought assessment; relatively low spatial resolution (>150,000 km squared/pixel)
- solution: GRACE have been downscaled to higher resolutions via assimilation into land surface model using GRACE data assimilation system (GRACE-DAS) and the Catchment land surface model (CLSM)
- Challenges with remote sensing: data continuity (satellites are designed for less than a decade of operaiton, not a problem for GRACE); data volumes (need infrastructure to store and serve data), data accessibility (need data scientists to process, curate, disseminate data)
- Terrestrial water storage was ignored by twentieth-century hydrologists
- GRACE was used to retrieve groundwater, soil moisture, surface water, snow, ice and permafrost
- GRACE data needs to be analyzed with caution, need to remove potential errors and variations
- GRACE has been used for grounwater depletion monitoring, accounting and prediction of global water budget, validating land surface models,drought monitoring, flood monitoring
- GRACE is used to monitor drought and flooding, and enables researchers to estimate evapotranspiration
- GRACE made global hydrologic data available and accesible
- It seems like there're two camps: lower basin states & upper basin states. What motivates each camp? what interest do they have?
- How does the order of water rights come to play in negotiating water cuts?
- If the federal government has to make decisions on cuts instead of the 7 states, how would it alter/set a precedent for the fed & gov's power in water rights? Is it legal?
- who would be impacted most by water cut in each state?
- which state should make the most cut? what arguments are there?
- How are water rights allocated (in terms of state and also individuals)?
- What are some of the players in each state? In the drought task force, there are cattlemen, farmer, water management companies, NGO, government near the border of the Colorado River Conservation District that provides water services. Who else? What are the dynamics?
- What is prior appropriation system (first in time, first in right)?
- state primacy/McCarran Amendment (state law control water rights/use, not federal law)
- Beneficial use (can't hoard water, if hoarding needs to be beneficial to society?)
- Water courts, colorado has water courts that adjudicate water use & protect water rights
- Winters v. US ensured water rights for native tribes. Aaron mentioned some tribes don't have access to water. Now the Supreme Court has decided the federal government don't have obligation to enforce their water rights, what can they do now?
- In Linda's paper, we can see that the distribution of dewatered pumps after sustainability goal is met is not uniformly distributed across space, but by subbasin. How can this be applied in the CRB scenario?
What spatial lens should we be mindful when examining CRB (state, tribes, and municipals close to the river)? Who is included in the conversation/involved in policy drafting/covered by new policy and who is not? Who will be most disadvantaged and how (lack of political power, financial savings, news outlet, access to deeper well) How does uncoordinated sustainability plan affect groundwater recharge? How are the locally sustainability metrics discussed and established? Why would people make sustainability metrics that does not prevent dewatered wells/pumps?