[Geospatial] [Caleb Kelly] [20210965]

Water management: GRACE to the rescue

• The Upper East Region (UER) of Ghana is in the north-east of Ghana

• Dry subhumid

• Land size of around 9,000 km2

• Agriculture as main occupation

• Impact of climate change is severe

• droughts

• floods1

• US$ 1 trillion fund to construct a dam in the UER for irrigation, flood

control, and electricity supply

1Geospatial and Geohazards Research Group, University of Nottingham Ningbo China2School of Architecture, Building and Civil Engineering, Loughborough University, UK

3Nottingham Geospatial Institute, University of Nottingham, UK

• In situ data in the UER is either insufficient or unavailable

• As a result, it is difficult to study the impacts of meteorological conditions on

water resources availability in the UER.

• Can globally available hydrological and meteorological data sets be used in

place of in situ data?

• What is the accuracy of these data sets in the UER?

• Does the size of the UER ensure the usability of time-variable gravity

data from the GRACE satellite missions?2

• How will the yet-to-be constructed dam influence water resources in the

area?

• GRACE

• JPL and CSR mascons solutions

• CSR Tellus Land Grids

• GLDAS-Noah hydrological model

• Precipitation data (P)

• GPM, CHIRPS, CPC

• Evapotranspiration data (ET)

• ERA-5, MOD16A2, GLDAS-Noah

• Other meteorological data

• Humidity, temperature, net radiation flux, wind speed

1. Yiran et al. 2016. Clim. Risk Manag. doi: 10.1016/j.crm.2016.09.003

2. Vishwakarma et al. 2018. Remote Sens. doi: 10.3390/rs10060852

3. Ferreira et al. 2014. IFGS. doi: 10.1007/1345_2015_137

Caleb Kelly1, Nicholas Hamm1, Craig Hancock2, Stephen Grebby3, Stuart Marsh3

• TWSA in the UER is increasing

• Rainfall is decreasing and accounts for only ~28% of changes in TWSA

• Evapotranspiration and other meteorological conditions in the UER support

water loss.

• GRACE measure water storage variations in the UER. GLDAS-Noah

underestimates water storage.

Introduction Methods

Problem

Data

Results and Conclusions

References

• Time series analysis: areal averages of data s(t)

𝑠 𝑡 = ∑!"#$ "!#!∑!"#$ "!

(1)

• Time series decomposition (multi-linear regression analysis)

𝑠 𝑡 = 𝑥$ + 𝑥% Δ𝑡 + ∑&'%( 𝐴& cos(2𝜋𝑘𝑡 − 𝜙&) (2)

• Terrestrial water budget (TWB) equation3

𝐹(𝑃 − 𝐸𝑇 − 𝑄) − )*)+ = 0 (3)

• Cross-correlation analysis and relative error analysis (three-cornered hat)

List of Abbreviations1. GRACE: The Gravity Recovery and Climate Experiment mission

2. GPM: Global Precipitation Measurement

3. CHIRPS: Climate Hazards group Infrared Precipitation with Stations

4. CPC: Climate Prediction Center

5. GLDAS: Global Land Data Assimilation System

6. TWSA: Total Water Storage Anomalies

7. TWCA: Total Water Content Anomalies

Source: Airbus/GFZ

Source: Ghanaweb

Fig1: Elevation and location of study area

Fig2: Contributors to annual floods: Bagre dam and rainfall

Fig3: Artist impression of GRACE satellites in orbit

Fig4: TWSA from GRACE Fig5: TWB based on Eq. (3)

Fig6: Rainfall vs. TWSA Table1: Components of time series decomposed using Eq. (2). * is used to represent filtered quantities