This document summarizes a research project analyzing trends in the Lake Chad Basin through data collection and analysis. Key findings from precipitation and river flow data across the basin using Mann-Kendall analysis suggest a significant decreasing trend in both precipitation and river flows that could be contributing to the shrinking of Lake Chad. However, data gaps exist and more collection is needed to strengthen conclusions. Future work is recommended to continue analyzing available data, collect new data points, and project future trends to better understand changes in the basin.
ICLR Friday Forum: Modelling of Future Flood Risk Across Canada (May 31, 2019)glennmcgillivray
On May 31, 2019, ICLR conducted a Friday Forum webinar lead by Dr. Slobodan Simonovic of Western University titled 'Modelling of Future Flood Risk Across Canada Under Climate Change.'
Climate change has induced changes in key climate variables and the hydrological cycle across Canada. With continuous emission of greenhouse gases, this trend is expected to continue over the 21st century and beyond. In this study, a macro-scaled hydrodynamic model is used to simulate 25 km resolution daily streamflow across Canada for historical (1961-2005) and future (2061-2100) timelines.
Future projections from 21 GCMs following four Representative Concentration Pathways (RCPs) were used for the analysis. Changes in the frequency and magnitude of historical 100-year and 250-year return period flood events and month of occurrence of peak flow are analyzed. Results obtained from uncertainty analysis for both return period flood events found that flood frequency will increase in most of the northern Canada, southern Ontario, southern British Columbia, northern Alberta, Manitoba and Saskatchewan. However, northern British Columbia, northern Ontario, Manitoba and northeastern Quebec will be facing decrease in flood frequency. Results indicate that 40%-60% of Canada’s 100 most populated cities including many prominent cities such as Toronto and Montreal are high at risk of increased riverine flooding under climate change.
Slobodan P. Simonovic is Professor of Civil and Environmental Engineering at the University of Western Ontario and Director of Engineering Studies at ICLR. Prof. Simonovic is globally recognized for his unique interdisciplinary research in Systems Analysis and has over 500 professional publications and three major textbooks. Prof. Simonovic was inducted to the Canadian Academy of Engineering in June of 2013.
ICLR Friday Forum: Modelling of Future Flood Risk Across Canada (May 31, 2019)glennmcgillivray
On May 31, 2019, ICLR conducted a Friday Forum webinar lead by Dr. Slobodan Simonovic of Western University titled 'Modelling of Future Flood Risk Across Canada Under Climate Change.'
Climate change has induced changes in key climate variables and the hydrological cycle across Canada. With continuous emission of greenhouse gases, this trend is expected to continue over the 21st century and beyond. In this study, a macro-scaled hydrodynamic model is used to simulate 25 km resolution daily streamflow across Canada for historical (1961-2005) and future (2061-2100) timelines.
Future projections from 21 GCMs following four Representative Concentration Pathways (RCPs) were used for the analysis. Changes in the frequency and magnitude of historical 100-year and 250-year return period flood events and month of occurrence of peak flow are analyzed. Results obtained from uncertainty analysis for both return period flood events found that flood frequency will increase in most of the northern Canada, southern Ontario, southern British Columbia, northern Alberta, Manitoba and Saskatchewan. However, northern British Columbia, northern Ontario, Manitoba and northeastern Quebec will be facing decrease in flood frequency. Results indicate that 40%-60% of Canada’s 100 most populated cities including many prominent cities such as Toronto and Montreal are high at risk of increased riverine flooding under climate change.
Slobodan P. Simonovic is Professor of Civil and Environmental Engineering at the University of Western Ontario and Director of Engineering Studies at ICLR. Prof. Simonovic is globally recognized for his unique interdisciplinary research in Systems Analysis and has over 500 professional publications and three major textbooks. Prof. Simonovic was inducted to the Canadian Academy of Engineering in June of 2013.
Aquifer recharge from flash floods in the arid environment: A mass balance ap...Amro Elfeki
Estimation of the infiltration/natural recharge to groundwater from rainfall is an important issue in hydrology, particularly in arid regions. This paper proposes the application of The Natural Resources Conservation Service (NRCS) mass balance model to develop infiltration (F)–rainfall (P) relationship from flash flood events. Moreover, the NRCS method is compared with the rational and the Ф-index methods to investigate the discrepancies between these methods. The methods have been applied to five gauged basins and their 19 sub-basins (representative basins with detailed measurements) in the southwestern part of Saudi Arabia with 161 storms recorded in 4 years. The F–P relationships developed in this study based on NRCS method are: F = 39% P with R2 = 0.932 for the initial abstraction factor, λ = 0.2. However, F = 77% P with R2 = 0.986 for λ = 0.01. The model at λ = 0.01 is the best to fit the data, therefore, it is recommended to use the formula at λ = 0.01. The results show that the NRCS model is appropriate for the estimation of the F–P relationships in arid regions when compared with the rational and the Ф index methods. The latter overestimates the infiltration because they do not take λ into account. There is no significant difference between F–P relationships at different time scales. This helps the prediction of infiltration rates for aquifer recharge at ungauged basins from monthly and annual rainfall data with a single formula.
Survey and Design of Gravity Fed Water supply system at a DadaGaun ,BanepaNepal Flying Labs
This is a presentation slide prepared for the final presentation during my 2nd year of study at Kathmandu Engineering ,Nepal.A village from Banepa where there is a scarcity of water has been chosen as the project study site and following surveying techniques have been implementation to develop a water distribution network for the community.
1.Leveling from water resource to the village
2.Traverse and Tacheometry around the village for topographical map generation
3.Design of water distribution routes
Using HEC-RAS to assess flash floods risk in arid regionsAhmed Saleh, Ph.D
Explain the utilization of HEC-RAS to two-dimensional simulation of flood wave propagation. also, show the application of ArcGis to draw flood risk maps.
The Development of a Catchment Management Modelling System for the Googong Re...GavanThomas
A scenario assessment model to assist the end-user in determining priorities for a series of agreed management prescriptions that can be enacted through controls on existing landuse
Scale-dependency and Sensitivity of Hydrological Estimations to Land Use and ...Beniamino Murgante
Scale-dependency and Sensitivity of Hydrological Estimations to Land Use and Topography for a Coastal Watershed in Mississippi - Vladimir J. Alarcon and Charles G. O’Hara
These slides discusses the SWOT behind the Exxon and Mobil merger. It starts with the history and background including its mission, vision, principles, culture and operations as well as some controversies. It proceeds with identifying some of the competitors for ExxonMobil. The SWOT prior to the merger is also presented together with some risks, issues and criticisms. Finally the current competitive advantages are also presented.
Offshore 1D infinite slope modeling in seismic conditions with openseesDAPPOLONIA
Evaluate where to lay an offshore pipeline is complex decision, D'Appolonia developed a model to assess offshore seismic slope stability.
The paper presents a 1D elasto-plastic numerical model developed in OpenSees software to study the dynamic response of a submerged infinite slope in seismic conditions. Results obtained for NC soil column profile are compared with theoretical solution.
Aquifer recharge from flash floods in the arid environment: A mass balance ap...Amro Elfeki
Estimation of the infiltration/natural recharge to groundwater from rainfall is an important issue in hydrology, particularly in arid regions. This paper proposes the application of The Natural Resources Conservation Service (NRCS) mass balance model to develop infiltration (F)–rainfall (P) relationship from flash flood events. Moreover, the NRCS method is compared with the rational and the Ф-index methods to investigate the discrepancies between these methods. The methods have been applied to five gauged basins and their 19 sub-basins (representative basins with detailed measurements) in the southwestern part of Saudi Arabia with 161 storms recorded in 4 years. The F–P relationships developed in this study based on NRCS method are: F = 39% P with R2 = 0.932 for the initial abstraction factor, λ = 0.2. However, F = 77% P with R2 = 0.986 for λ = 0.01. The model at λ = 0.01 is the best to fit the data, therefore, it is recommended to use the formula at λ = 0.01. The results show that the NRCS model is appropriate for the estimation of the F–P relationships in arid regions when compared with the rational and the Ф index methods. The latter overestimates the infiltration because they do not take λ into account. There is no significant difference between F–P relationships at different time scales. This helps the prediction of infiltration rates for aquifer recharge at ungauged basins from monthly and annual rainfall data with a single formula.
Survey and Design of Gravity Fed Water supply system at a DadaGaun ,BanepaNepal Flying Labs
This is a presentation slide prepared for the final presentation during my 2nd year of study at Kathmandu Engineering ,Nepal.A village from Banepa where there is a scarcity of water has been chosen as the project study site and following surveying techniques have been implementation to develop a water distribution network for the community.
1.Leveling from water resource to the village
2.Traverse and Tacheometry around the village for topographical map generation
3.Design of water distribution routes
Using HEC-RAS to assess flash floods risk in arid regionsAhmed Saleh, Ph.D
Explain the utilization of HEC-RAS to two-dimensional simulation of flood wave propagation. also, show the application of ArcGis to draw flood risk maps.
The Development of a Catchment Management Modelling System for the Googong Re...GavanThomas
A scenario assessment model to assist the end-user in determining priorities for a series of agreed management prescriptions that can be enacted through controls on existing landuse
Scale-dependency and Sensitivity of Hydrological Estimations to Land Use and ...Beniamino Murgante
Scale-dependency and Sensitivity of Hydrological Estimations to Land Use and Topography for a Coastal Watershed in Mississippi - Vladimir J. Alarcon and Charles G. O’Hara
These slides discusses the SWOT behind the Exxon and Mobil merger. It starts with the history and background including its mission, vision, principles, culture and operations as well as some controversies. It proceeds with identifying some of the competitors for ExxonMobil. The SWOT prior to the merger is also presented together with some risks, issues and criticisms. Finally the current competitive advantages are also presented.
Offshore 1D infinite slope modeling in seismic conditions with openseesDAPPOLONIA
Evaluate where to lay an offshore pipeline is complex decision, D'Appolonia developed a model to assess offshore seismic slope stability.
The paper presents a 1D elasto-plastic numerical model developed in OpenSees software to study the dynamic response of a submerged infinite slope in seismic conditions. Results obtained for NC soil column profile are compared with theoretical solution.
D’Appolonia: Challenges and opportunities for IESCDAPPOLONIA
This presentation reviews D’Appolonia’s experience
and describes how the approach to the independent
environmental and social consultant’s (IESC) role has
evolved thanks to new tools and technologies and
refi nement of fi nancial institutions’ policies.
DSD-INT 2016 Regional groundwater flow systems in the Kenya Rift Valley - Mur...Deltares
Presentation by Patrick Murunga Wakhungu (University of Twente) at the iMOD International User Day, during Delft Software Days 2016. Tuesday 1 November 2016, Delft.
Storm intensity not increasing - factual review of engineering data - Canada ...Robert Muir
Storm Intensity Not Increasing. Review of Weather Event Statement in Insurance Bureau of Canada’s “Telling the Weather Story” prepared by Institute for Catastrophic Loss Reduction. Environment Canada analysis and engineering dataset review for Canada and Ontario, July, 2015. "Old extremes are the new normal".
As illustrated through these slides, Telling the Weather Story makes a statement on the increased frequency of storms and weather events, indicating that in parts of Canada, events that occurred every 40 years are occurring every 6 years, due to climate change.
The statement on increased frequency is unfounded as (based on ICLR's IPCC source and material and IBC's presentation to the Empire Club of Canada) it is based on a theoretical shift in temperature frequency from a global climate change report, and is contrary to Environment Canada’s actual analysis and data on local rainfall intensity trends.
The Telling the Weather Story statement on increased storm intensity, based on temperature theory has been i) embraced as rainfall facts and research by many organizations, ii) embellished to apply to extreme rainfall, and iii) considered in policy and economic reports. Organizations promoting the misinformation in the statement include TD Economics, The Toronto Star / thestar.com, CBC News, Canadian Chamber of Commerce, Columbia Institute Centre for Civic Governance, Civic Action, CBC Doc Zone, The Calgary Sun, CanadianUnderwriter.ca, Aviva Canada, Insurance Bureau of Canada.
Due to the unfounded Telling the Weather Story Weather Story statement, policies and efforts toward mitigating increasing urban flood damages may be misdirected to climate change mitigation, as opposed to more effective risk identification/management efforts, urban planning / stormwater management policies and infrastructure remediation / capital investment efforts that address the root causes of increased damages, not related to theoretical storm frequency shifts.
It is an inconvenient truth that increases in temperature, and in theory water vapour, have not translated into increased rainfall intensities. Research at MIT and Columbia in fact states the contrary, that rainfall intensities can decrease at higher temperatures and that intensities are governed by CAPE and not temperature.
Environment Canada has been correcting false reporting by the insurance industry on this topic of increasing rainfall frequency, for example correcting CBC reporting:
http://www.cbc.ca/news/canada/windsor/more-than-half-of-homeowners-insurance-claims-stem-from-water-damage-broker-says-1.3291111
Or recent reporting in Canadian Underwriter, specifically on the Weather Story:
http://www.canadianunderwriter.ca/insurance/new-ibc-flood-model-shows-1-8-million-canadian-households-at-very-high-risk-1004006457/
CBC/Radio-Canada Ombudsman Guy Gendron's ruling highlights media issues with accurate extreme rain reporting here as well: https://bit.ly/2RPx7p9
Presented by IWMI’s Girma Ebrahim at the 26th General Assembly of the International Union of Geodesy and Geophysics (IUGG), held in Prague - Czech Republic, on June 25, 2015.
Session - Societal Relevance of Groundwater: Ever Increasing Demands on a Limited Resource
Objectives:
Develop a replicable integrated model (methodology) for evaluating the extent and development potential of renewable (non-renewable) groundwater resources in arid lands, with the Eastern Desert of Egypt as a pilot site.
The model will be replicable for similar arid areas; North of Sudan, Tibesty, Yemen, and Saudi Arabia.
Building national capacities.
DSD-Kampala 2023 Analytic Tools for Cooperative Water Resources Assessments i...Deltares
Presentation by Dr Michael Kizza, Deputy Executive Director, Nile Basin Initiative (NBI), at the Symposium Models and decision-making in the wake of climate uncertainties, during the Deltares Software Days - Kampala 2023 (DSD-Kampala 2023). Wednesday, 4 October 2023, Kampala, Uganda.
This study explains the use of remote sensing data for spatially distributed hydrological modeling using the MIKE-SHE software used in Tarim River Basin CHINA
2012 02 The State of the Severn Report Dr. Rhoda Ballinger, Cardiff UniversitySevernEstuary
The State of the Severn Report
Rhoda Ballinger has a degree in Geography, a Postgraduate Certificate in Education and a PhD from the University College of Wales, Aberystwyth. Over the last decade, particularly as a member of the Marine and Coastal Environment Research Group, she has engaged in a quest for model institutional and policy frameworks to deliver Integrated Coastal Management (ICM). Currently, her interest in non-statutory and participatory processes for ICM is reflected in her postgraduate students' research topics. Keen to develop more than an academic perspective on coastal management, Rhoda has been heavily and actively involved in the development and day-to-day running of a number of international, national and local coastal and estuary management projects, including the Severn Estuary Partnership.
This presentation will build on the launch of the State of the Severn Estuary Report at last year’s Forum event. The presentation will highlight the current development of indicator sets and specific report cards detailing the ‘State of the Severn in specific themed areas. The presentation will focus mainly on the approach taken and the initial findings.
2. Presentation Overview:
1. Background Research/Literature Review
2. Data Acquisition
3. Data Analysis
4. Watershed Delineation and Mapping
5. Basin Trends and Conclusions
3. Directly affected countries:
• Chad, Niger, Nigeria, Cameroon
Indirectly affected countries:
• Central African Republic
• Sudan
• Algeria
Part 1: Background Research and Literature Review
4. History of Lake Chad
Part 1: Background Research and Literature Review
5. Low adaptive capacity of arid regions
Part 1: Background Research and Literature Review
6. Decreased lake size could be due to
decreased inflow
Part 1: Background Research and Literature Review
7. IPCC GCM report on water and climate
change
Regions experiencing significant increases or decreases in precipitation –
The Lake Chad Basin (LCB) marked by a significant decrease
Part 1: Background Research and Literature Review
8. On the causes of shrinking Lake Chad
Part 1: Background Research and Literature Review
9. Model of inflow
for Lake Chad to
return to pre-
1960s levels
Part 1: Background Research and Literature Review
10. Impact of droughts, split, and irrigation model
Part 1: Background Research and Literature Review
11. Historical Lake
Levels show cause
could be
part of a natural
cycle
Part 1: Background Research and Literature Review
12. Part 2: Data Acquisition
GRDC: River Discharge Data
• Application process
• Received daily and monthly data
• Daily Data Includes:
• Lake Chad Basin
• 11 Nigeria Stations
• 21 Central African Republic Stations
• 12 Chad Stations
• Congo River Basin (for future diversion impact
study)
• 44 stations
13. NOAA Precipitation and Temperature Data
• Daily and monthly data for:
• Cameroon (3 stations)
• Nigeria (10 stations)
• Central African Republic (17 stations)
• Chad (11 stations)
Part 2: Data Acquisition
14. Part 3: Data Research and Analysis
KEY
Precipitation
Station: Date
Range
Flow Station:
Date Range
15. Justifying data selection
Criteria for evaluating monotonic trends
• Minimum of 5 years monthly data
• Data gaps less than 1/3 the total data
Climatic analysis of data
• Minimum of 50 years preferable
• For lack of consistent data, 30 years of data was considered useful in this
study
Part 3: Data Research and Analysis
16. Flow Large Data Ranges
Flow Selected Stations:
Ndjamena: 1976-1991
Ouli Bangala: 1978-1990
Hadejia: 1963-2006
Wudil: 1963-2005
Bossangoa: 1986-1992
Bangui: 1935-2007
Part 3: Data Research and Analysis
17. Precipitation Large Date Ranges
Precipitation Selected Stations:
Ndjamena: 1950-2016 (67%)
Bousso: 1952-1978 (91%)
Magaria: 1980-1992 (90%)
Moundou: 1950-2016 (62%)
Pala: 1952-1978 (92%)
Garoua: 1973-2016 (71%)
Bour: 1950-1980 (94%)
N Guigni: 1926-2016 (79%)
Sarh: 1950-2016 (64%)
Bouca: 1950-1965 (96%)
Bangui: 1950-1980 (93%)
Part 3: Data Research and Analysis
18. Part 4: Watershed Delineation
• Accessed 90 m accuracy data from
CGIAR-CSI GeoPortal
• Downloaded about 20 DEM
files/squares that encompass the
Watershed
• Use GIS to delineate watershed and
sub-basins
• Can determine which stations we
have data for and where these
stations are located in the sub-basins
19. Lake Chad Basin
• Huge area2,500,000 km^2 at
90 m accuracy
• Too large for even ArcGIS to
handle
• Must decrease accuracy while still
maintaining correct watershed
Part 4: Watershed Delineation
20. Problem Solving: Lake Chad Basin Delineation
• Use CIMA watershed delineation to determine correct Lake Chad Basin
boundaries
• Used AutoCAD to outline basin, and then used previous CIMA file to
correctly scale and locate the basin
CIMA Watershed Boundaries
AutoCAD tracing of
watershed
Part 4: Watershed Delineation
21. Problem Solving: Lake Chad Basin Delineation
• Imported AutoCAD basin
outline and DEM files into
Global Mapper, to chop data
to watershed size and
reduce cell size, further
decreasing the size of the
data
• Exported the cropped DEM
files and imported them into
WMS
• Used WMS functions in
order to delineate
watershed and sub-basins
Part 4: Watershed Delineation
Global
Mapper
WMS
22. Lake Chad Basin Delineation
Part 4: Watershed Delineation
Comparison between WMS Delineation (left) and CIMA delineation (right)
23. Lake Chad Basin Delineation: Adding the Lake
Part 4: Watershed Delineation
• Used GIS raster calculator to add
290 m elevation lake (historic size)
and 280 m elevation lake (2008 size)
• Compared with Google Earth
to check accuracy of raster
calculator/elevation method
24. Lake Chad Basin Delineation using WMS
Sub-Basin 1Sub-Basin 2Sub-Basin 3Sub-Basin 4Sub-Basin 5Overall Basin
Part 4: Watershed Delineation
25. Part 5: Basin Trends and Conclusions
Key:
Precipitation
Flow
26. Mann-Kendall analysis
Part 5: Basin Trends and Conclusion
Sen slope; estimate of rate
of change in the trend
Test statistic; large
absolute value
indicates a trend
β0 is the null hypothesis (no trend);
when non-zero, the null hypothesis
is rejected
n = number of data points
Tau statistic; similar
to correlation
coefficient
Linear regression of the data
Significance Equations
27. Relative Factor
• Used to fill missing data
• Stations with spatial relations could be plotted on x (station A) and y-
axis (station B) to determine a linear fit
• If R>0.8, the linear relationship between the data can be used to
transform data from station A to station B
Part 5: Basin Trends and Conclusion
28. Part 5: Basin Trends and Conclusions
Ndjamena
Moundou
Bangui
Bossangoa
Wudil
Hadejia
Station Precipitation
Date Range
Flow Date
Range
Ndjamena 1950-1978 1953-2009
Bangui -------- 1935-2007
Bossangoa -------- 1951-1972
Hadejia -------- 1963-2005
Wudil -------- 1963-1991
Moundou 1950-1978 ----------
Significant: CI>90%
Seasonal Trend Analysis:
Rainy season
29. Conclusion of Data Analysis and Results
• Map of trends concludes decrease in flow
and precipitation could be a significant
cause of the shrinking of the Lake Chad
• Conclusion coincides with background
research
Part 5: Basin Trends and Conclusion
30. Data Discussion
• Historically, countries around Lake Chad haven’t focused on
investments in data collection
• Data is sporadic and infrequent, many sets are missing too large of
gaps to run Mann-Kendall analysis
• Relative analysis was able to fill some of the data gaps
• Using only one month out of the year may produce a more
continuous series of data to run in the Mann-Kendall (i.e. August or
September, during the rainy season)
Part 5: Basin Trends and Conclusions
31. Future Work
• Further analysis and organization of the data must be done
• Collection of more data sets to verify and fill gaps in the data
• More research on and a better understanding of the Mann-Kendall
analysis
• Finding more data for stations in upper sub-basins (Sahel region)
• Using historical data to project future trends
• Analyzing impact of the basin transfer project on the the Lake Chad
Basin and Congo River Basin
Part 5: Basin Trends and Conclusions
32. Thank you!
Any questions?
Special thanks to: Dr. Guo, Bibi, David, Mr. Song, Yang, and all others who have graciously helped with our project and
our internship
Editor's Notes
Discuss goals/purpose
Economy depends on agriculture and fishing which depends on lake
Water use for drinking and daily activities
Around 30 million people depend on Lake Chad
25000 to 15000 km^2
This is the historywhat is the cause?
Huadong’s major goal before going forth with the water diversion project
Anthropogenic such as dams or irrigation or natural climate variation
Brittanica: Travelers reported high water levels and overflow into the El-Ghazal during the 13th and 19th centuries. In 1870, for example, Lake Chad covered some 10,800 square miles (28,000 square km). At the turn of the 20th century the lake began to diminish in size, but by the 1920s it had recovered, and in 1956 it again overflowed into the El-Ghazal. During the 1970s and ’80s the amplitude of the lake’s annual variability was the highest recorded in the 20th century, with average levels falling below long-term norms; the surface area was reduced to less than 1,500 square miles (3,900 square km) for a time in the mid-1980s and again in the early 21st century. The corresponding variability in rainfall appears to have been related to the effects of environmental degradation.
Recent studies have confirmed that particularly the arid and semi-arid regions of Africa are the most vulnerable
areas to climate variability and change because of multiple stresses and low adaptive capacity (Osman-
Elasha, 2007; IPCC WGII, 2007)
The changes in the lake chad may be due to natural climate variability and droughts and natural erosion
Could also be due to human activity such as unsustainable farming practices that use irrigation or grazing that removes plants important to the hydrology of the lake
Map of gauging station on the Chari-Logone R., where Lake Chad receives an estimated 80% of its inflow
Study on discharge measurements
Has daily measurements, but not throughout the course of a month at the same data station
Used velocity measurements from ADCP (acoustic principle) to get a 3-dimensional view of the velocity. The map of the velocity distribution in the cross sectional area is included in the report.
Concludes rating curves should be used with caution during flood/ estimating peak flow. During floods water burst into banks of the river system and caused lower flow than expected in the river, sometimes by 50%
https://www.ipcc.ch/pdf/technical-papers/climate-change-water-en.pdf
The intergovernmental panel on climate change technical report on climate change and water
The lake chad region is one of significant decrease
Historical split in the northern and southern basin caused seasonal changes in hydrology
Northern basin separated by great barrier and almost always dry now
Of interest because this is a new occurance in the basin; in models, this split makes the lake chad more difficult to return to pre-1960s lake chad, could be a turning point in hydrologic history
This graph shows what inflows would be needed over the course of years to return Lake Chad to pre-1960s levels. These flow rates are highly unlikely to happen in nature.
From On the causes of the shrinking of Lake Chad
Climate in 1990s was not conducive to a full recovery from previous droughts
These results clearly show that even without irrigation withdrawals, the 1952–2006 mean climate state does not favor a single lake.
We also tested the impact of temperature change by increasing the annual average air temperature by 2K (approximately the observed temperature increase from 1952– 2006), and found that modeled inflow decreased by about 10% relative to climatology due to increased evapotranspiration
Figure 5 shows that with a recurring net annual inflow of 50 km3 yr−1, the two lakes would have merged into one in about four years, and a total of 10 years would be required for the lake to resume its 1963 size(9.25 m annual minimumlake level). For an annual inflow of 60 km3 it would take five years to recover to the 1963 size. A larger annual inflow not only implies a shorter time but also a smaller total volume needed for recovery to a given size. However, because 1963 was one of the wettest years in the study period (and had low irrigation withdrawals), it is unlikely that an equivalent/largerinflow(after irrigationusage) will occur for even one year, let alone multiple consecutive years, under foreseeable climate conditions.
GRDC
Lat/Long of each station
Catchment area
Altitude of Station
Mean Daily Discharge
Mean monthly Discharge
NOAA
Lat/Long of each station
Elevation of station
Daily precipitation total
Max daily temperature
Min daily temperature
National nonpoint source monitoring program by EPA
Huge area2,500,000 km^2 at 90 m accuracy
Too large for even ArcGIS to handle. Must decrease accuracy while still maintaining correct watershed
-“Mann-Kendall trend test is a nonparametric test used to identify a trend in a series, even if there is a seasonal component in the series.”
Null hypothesis states that β0 = 0 and no trend is present
S indicates an upward trend (large positive number) or downward trend (large negative number)
τ, the test statistic, is the equivalent of a correlation coefficient (-1 to 1)
When S and τ are significantly different from zero, null hypothesis is rejected and a trend is indicated
Sen slope estimator used to find rate of change (β1)
100% of precipitation from May- October
Over 50% of the data is between aug-oct
Used months of September for flow data and September or August for rainfall
NDJA 1953-2009 GRDC, 1950-1978 NOAA
BANGUI 1935-2007 GRDC
BOSSANGOA 1951-1972 GRDC
HADEJIA 1963-2005 GRDC
WUDIL 1963-1991 GRDC
MOUNDO 1950-1978 GRDC
Flow is:
Precipitation is:
Relate to previous research
Relative analysis = Bossangoa and Moissala,
Often times the relative analysis did match, but the data in both sequences was missing too much and didn’t create a full enough data set
CIMA said they had data in their files, but it was not found in the files given (i.e. for the Ouli Bangala station)
Further analysis Outside influences need to be eliminated for “pristine” flow data to detect changes due to climate