Download Climate and water – an African perspective

25 January 2006
Climate and water – an African perspective
William J. R. Alexander, Professor Emeritus,
Department of Civil and Biosystems Engineering, University of Pretoria, South Africa.
Email [email protected]
In this chapter it is demonstrated with a high degree of assurance that the IPCC
predictions of adverse effects of global warming on water supplies, floods and
droughts on the African continent are without foundation. The examples used are
from ancient Egypt in the north and modern South Africa in the south. All the data
used in the analyses are from official data banks. The analytical methods used in the
study were developed by the author. Details are provided in two published papers and
a comprehensive technical report now in the final stages of preparation. (Alexander
2005a, 2005b and 2006.)
There is a very long history of hydrological studies related to rainfall, river flow and
the vulnerability of communities to the occurrence of floods, droughts and water
shortages. Their publications and findings have been completely ignored in the
climate change literature.
The issues
Global warming and its postulated (as yet unproven) adverse consequences on human
welfare have become the most important scientific issues of all time. Never before in
history have the heads of the world’s most powerful nations issued a joint
communiqué on international policy relating to a scientific subject, and the academies
of science of these nations issued a joint statement prior to the meeting designed to
influence their decision. There have been subsequent high-level international
discussions and developments that have further confused the situation.
There are three, not two, broad groups of scientists in this field. They are concerned
scientists, dissenting scientists and unconcerned scientists. Frequently heard claims by
concerned scientists in the climatological and environmental sciences are that there is
close to unanimity (consensus) on global warming and its consequences. These claims
ignore the presence of the much larger community of unconcerned scientists in the
applied sciences, principally engineering and agriculture. They shrug their shoulders
and maintain that the views of the concerned scientists are unproven and little more
than untested hypotheses. These scientists have no incentive to participate in the
debate and publish their views, which remain largely unrecorded in the scientific
literature.
There is a third group in the economic sciences whose concern is the economic
consequences of action proposed to control global warming. Their general approach is
that the recommendations by concerned scientists to limit future global warming will
Climate and water.doc
25 January 2006
2
cause more damage to human welfare via the costly economic measures than the
postulated consequences if no action is taken.
Fundamental to the entire problem is the inability of the concerned scientists to
provide solid proof of adverse changes in numerical terms at an acceptable level of
confidence (believability) that will enable others to apply this knowledge when
commissioned to undertake preventive or ameliorative measures.
I am in a position to assess the validity of the IPCC claims of postulated adverse
consequences on human welfare. I have a career-long concern relating to the
vulnerability of millions of people on the African continent presently living in
conditions of poverty, malnutrition and disease, to the vagaries of nature. Their three
major concerns are the climatic extremes – floods and droughts – and the certainty of
increasing water shortages as the available resources approach the limits of
exploitation.
There is also an increasing likelihood of cross-boundary disputes regarding water
allocations from international rivers in Africa. Will global warming increase the risk
of international disputes over the remaining unutilised resources? How will global
warming affect the growing demands of environmentalists that rivers be sustained in
an environmentally healthy condition as the demand for human welfare continues to
grow? These are very important international issues that require advanced
hydrological characterisation of the properties of rainfall and river flow.
In addition to my own studies I have served on a number of national and international
science coordinating bodies. These include the South African National Programme for
Environmental Sciences, and the United Nations Scientific and Technical Committee
on Natural Disasters from 1994 to 2000. I was commissioned by this body to
undertake a study titled Risk and Society – an African Perspective (Alexander 1999).
This is the basis for some of the philosophical material below. The rest of the material
is based on a diligent, three-year study of the largest and most comprehensive
hydrological and meteorological database yet assembled for this purpose in South
Africa and possibly elsewhere in the world. The results were summarised in two
recent refereed papers. (Alexander 2005a and 2005b.) I am now in the final stages of
preparation of a comprehensive technical report An assessment of the likely
consequences of global warming on the climate of South Africa. (Alexander 2006.) A
92-page extended summary in pdf format has already been widely distributed in South
Africa and is available at no charge.
The point of departure in this chapter is the knowledge that theoretically based
concerns, however convincing they may be, are an inadequate basis for predictions
that could have profound effects on the welfare of humankind. What the world
requires is solid, numerical evidence that demonstrates at an adequate level of
believability, that the postulated adverse effects of global warming are real and are
already happening. In the absence of this evidence, the views of the majority of
scientists in the applied sciences are that the alarmist claims are no more than untested
and unproven hypotheses.
Two major issues should be kept in mind while reading this chapter. The first is the
complexity of the climatic processes, particularly their non-uniformity and abruptness
of changes in space and time. While changes in the mean conditions are important, it
is the long-term variability about the mean and the variability of the mean itself that
are the dominant concerns in evaluation and adaptation studies. The second is the
3
impossibility of describing these processes and their interrelationships in any
mathematical process model, however complex, bearing in mind that these models
have to be continuous in space and time. If engineering hydrologists have been unable
to develop universal, mathematical process models for simple rainfall-runoff
processes after more than 50 years of concentrated, international efforts, what
reliability can be placed on global climate models that are purported to be able to
predict long-term changes in the infinitely more complex climatic systems?
South Africa, with its wide range of climatic conditions from high rainfall in the east
to desert conditions in the west, and from winter rainfall regions in the south, via
year-round rainfall through to summer rainfall over most of the country, is ideal for
evaluating the consequences of global warming. Note also that it is the redistribution
of solar energy that drives the climatic processes – not temperature. South Africa lies
within the path of maximum poleward redistribution of solar energy and is
consequently in a suitable location for evaluating the consequences of variations in
solar activity. South Africa therefore provides the ideal testing ground for
international climate change theory and its postulated consequences.
The birth of early civilisations in Africa
A lot has been said and written about the adverse effects of climate change. The
impression is created that all change is undesirable. This view is untenable in the light
of the highly variable climatic conditions on the African continent in both space and
time. A very good example is the climatic conditions that prevailed during the
thousands of years of development of the early civilisations in ancient Egypt. The
climate was hot, arid, cloudless and rainless with high levels of solar radiation.
These properties, which are often proclaimed as being adverse consequences of
climate change in the IPCC literature, had no adverse effects on the growth and
maintenance of the high level of civilisation. The welfare of the people was directly
dependent on the fertile soils on the floodplain of the Nile River and their inundation
by the annual floods. These floods were essential for the agricultural activities on
which the civilisations were based. This situation immediately casts doubts on claims
by concerned scientists that increases in temperature and floods, are undesirable
consequences of climate change.
The single, most important climate-related concern was the absence of life-giving
floods during sequences of years of drought. The storage of grain to overcome
seasons of inadequate river flow was common practice. The required capacity of the
grain storage structures had to be determined by experience, which in turn required
reliable measurements. This requirement was the beginning of the application of
observation theory, which continues to dominate process theory used by concerned
scientists through to the present day.
3000 years of hydrological observations
The following biblical quotation is relevant. Behold, there came seven years of great
plenty throughout the land of Egypt - and there shall arise after them seven years of
famine. Genesis, 41, 29-30
The earliest evidence of routine hydrological observations is the regular horizontal
engravings on a stone wall on an island at Aswan in the Nile River. The oldest
surviving records of the flows in the river are those engraved on fragments of stone
now held in the Palermo Museum in Sicily. They have been traced back to the period
4
3000 – 3500 BC. (Biswas 1970.) It is almost certain that early records were the basis
for the biblical prediction that was documented some 1500 years after the
commencement of the observations.
The Temple of Edfu on the banks of the Nile River dates back to 240 BC. A series of
underground corridors leads to a chamber connected to the river, so that observations
could be made of changes in river water levels. The public were denied access to the
observation system. Kom Umbu was subsequently built in Roman times. There is a
large well in the open courtyard with a spiral staircase winding down its sides. The
bottom of the well is connected to the river. An annual tax was levied on farmers
whose land benefited from inundation by the floodwater. By counting the number of
steps under water each year, the tax collectors could determine which lands were
inundated and therefore taxable.
This situation illustrates the linkage between the hydrologists who analysed the
historical flood levels; the administrators who were responsible for maintaining the
structures and delivering the services to the people; the economists who calculated the
costs of providing the services and the income from taxes; and the political decision
makers who had to balance the public expenditures and incomes from taxation.
For the sake of illustration, assume that the high priests at Edfu proclaimed that the
flows in the Nile River had become more variable during the previous 50 years and
that this situation would worsen in future. The consequent changes in river flow
would result in the increase in damaging droughts as well as an increase in damaging
floods. How would the hydrologists, administrators, economists and political decision
makers have reacted?
Clearly, no action could be taken without numerical quantification of the changes in
the frequency and magnitudes of the annual flows in the river. Hydrologists would
have to provide this information. Their first reaction would be to analyse the past
records in order to determine whether or not there had in fact been changes in the
frequency and magnitude of floods and droughts during the period of record. If these
changes were present, the hydrologists would then be able to estimate probable future
changes in the numerical (as opposed to descriptive) terms. This information would
be used in turn by the administrators, economists and political decision makers.
The fundamental need for accurate measurements of the flow in the Nile River was
obviously apparent thousands of years ago. In 641 AD - more than 1400 years ago an architecturally beautiful water level gauging structure was built on Rodda Island at
Cairo. The record from the Rodda Nilometer is the longest available hydrological
record in the world. Why have climate change scientists not used this information
instead of unreliable proxy data from tree rings and ice cores?
In the late 1940s the civil engineer R.E. Hurst (1948) analysed 1080 years of data
from the Rodda Nilometer recorded during the period 641 to 1946, which he intended
using to determine the required storage capacity of the proposed new Aswan High
Dam. He found an unexplained anomaly in the data. He then analysed other long
geophysical records, where he found the same anomaly. These were sediment
deposits in lakes (2000 years), river flow (1080 years), tree rings (900 years),
temperature (175 years), rainfall (121 years), sunspots and wheat prices. This anomaly
became known as the Hurst phenomenon, or Hurst’s Ghost.
It is important to note his use of proxy data from a variety of other climate-related
processes in an attempt to quantify the numerical properties of the annual flows in the
5
Nile River. Even more important was Hurst’s conclusion that the proxy data exhibited
the same anomalous properties as river flow. Recently, some 50 years later, proxy tree
ring data was used as a basis for developing the critically important models for
climate change scenarios. These have been the subject of severe criticism, but neither
the concerned scientists nor their critics appear to have taken the trouble to examine
the wealth of hydrological publications that describe the attempts of hydrologists to
solve the problem during the period 1950 to 1970. A sense of frustration is evident in
the many research papers published in the hydrological literature at that time. The
following are some important examples that are relevant to the scientifically naïve
views expressed in the IPCC publications.
Mandelbrot and Wallis (1968) introduced the terms ‘Noah Effect’ to describe the fact
that extreme precipitation can be very extreme indeed, and ‘Joseph Effect’ to describe
the fact that a long period of high or low precipitation can be extremely long.
Yevjevich (1968) stated that attempts at long-range forecasts of water supply based
entirely on meteorological processes had misdirected research and raised false
expectations. Wallis and Matalas (1971) noted that there was a tendency for high
flows to follow high flows and for low flows to follow low flows. This was referred to
as hydrologic persistence and was attributed to storage processes in the atmosphere or
in the drainage basin, either surface or subsurface.
Yevjevich (1972) commented that one of the earliest deterministic methods used in
hydrology was the application of the concept of almost-periodic series to various
hydrological sequences in search for their hidden periodicities. However, their
extrapolation as the prediction of future events represented one of the most
spectacular failures of past hydrologic investigations. [My studies show that he was
wrong.]
Wallis and O’Connell (1973) maintained that the presence or absence of long-term
persistence could radically alter the expected value of reservoir design storage and
hence the estimate of the firm yield. [I agree.] Finally, Klemes (1974) commented that
ever since Hurst published his famous plots for some geophysical time series, the
classical Hurst phenomenon continued to haunt statisticians and hydrologists, and that
attempts to derive theoretical explanations from the classical theory of stationary
stochastic processes have failed.
Note that although the cause of this anomalous behaviour must have been the result of
perturbations in the climatic driving mechanisms, no attempts were made to establish
this linkage. The simple reason was that there were no concurrent climatological
measurements at the required space and time resolutions, and no adequate theory
linking climatic perturbations directly with the observations. [I believe that my studies
will lead to the eventual explanation of the Hurst phenomenon.]
It is ironical that fifty years ago civil engineers observed and reported anomalies in
long, reliable hydrological records including rainfall and river flow. This caused them
to examine proxy data where they found the same anomalies. Now, fifty years later
climate change scientists have completely ignored both the wealth of hydrological
data as well as the well-reported multiyear anomalies in the data. They have
developed complex models of global climate based on suspect proxy data to predict
adverse changes in the hydrological processes, for which there is no believable
evidence. Stochastic hydrologists are in a position to assist but their offers have been
ignored.
6
Early South African studies
There are many properties of annual rainfall sequences that have been observed in
South Africa for a century or more that remain unresolved. The primary and most
important property is whether or not there has been a change in the mean annual
rainfall during the period of continuous records. This has been the subject of a number
of reports of high level commissions of enquiry appointed by the government of the
day to examine the causes and possible amelioration measures of recurrent droughts.
Whether or not the droughts were caused by a systematic reduction in rainfall over
South Africa was the key issue.
In 1948, forty years before the establishment of the IPCC, the Department of
Irrigation published a 160-page memoir by the civil engineer D.F. Kokot titled An
investigation into evidence bearing on recent climatic changes over southern Africa,
(Kokot 1948). It contained 418 references, including reports by early travellers and
missionaries. He found no evidence of a general decrease in rainfall or river flow,
despite increases in CO2 emissions. He concluded that there was no evidence of a
linkage between CO2 emissions and rainfall over South Africa.
The report of the Desert Encroachment Committee appointed by the Minister of
Agriculture was published in 1951. (van der Merwe et al 1951). This was a thorough
multidisciplinary report by a team of South Africa’s leading scientists. They
concluded that there was no evidence of a general decrease in the rainfall in South
Africa that could be attributed to climate change.
In the mid-1970s, hydrologists in the South African Department of Water Affairs
encountered the same problem that Hurst had observed 25 years earlier. There were
far too many periods when restrictions had to be imposed on the water supply from
the Vaal and other major rivers. It became clear that the reservoir capacity-yield
model then in use in South Africa was deficient, and that this was probably due to
assumptions regarding the river flow characteristics. A team of hydrologists was
assembled to examine assumptions relating to the properties of the river flow
sequences used in storage capacity-yield analyses. The mathematical models did not
provide any insight, but graphical analyses showed that there was a very clear 20-year
(later 21-year) periodicity in the data and that this was the cause of the difficulty. I
instigated and headed the studies. The findings were published in 1978 in a
Department of Water Affairs’ technical report titled Long range prediction of river
flow – a preliminary assessment (Alexander 1978). The graphs showed that there was
a clear pattern in the accumulated departures from the record mean values and that
these were approximately synchronous with sunspot activity. These were quite
different from random deviations.
My research along these lines continued. In the Vaal River, the periodicity
approached the 95% level of statistical significance required in many engineering
applications. My paper Floods, droughts and climate change was published in the
South African Journal of Science in August 1995. (Alexander 1995.) I detailed my
analytical methods and also referred to the Hurst phenomenon. I concluded: The acid
test that will demonstrate whether or not the 20-year periodicity continues is at hand.
If the drought is broken by widespread rainfall during the next two years it will surely
be conclusive.
Four months after the publication severe floods occurred over a wide area of southern
Africa. Lives were lost and the drought was broken. The periodicity of flows in the
7
Vaal River reached the 95% confidence level confirming my predictions and my
model.
I was also the first person to report a sustained increase in the rainfall over South
Africa based on a study of 7141 years of district rainfall data. Why have no
climatologists acknowledged this undeniable increase? Surely this is good news. This
denial of the beneficial consequences of global warming has become a trademark of
climate change scientists.
Clash of theories
As shown above, observation theory based on numerical measurements is as old as
civilisation itself. The design of every structure exposed to the forces of nature and
every storage dam on a river designed to supply water, is based on an analysis of
recorded data. Process theory, which is the study of the processes that produce the
rainfall and therefore river flow, does not feature in the design of these structures
anywhere in the world, from ancient civilisations through to the present day.
In contrast, climatology is a young science and is based on abstract process theory
supported by limited measurements. Traditionally, one of the main thrusts of
climatology has been the study of climate on a geological time scale extending many
thousands of years back in time. It is therefore understandable that climatologists
interested in climate change chose to use centuries-old proxy data such as data
derived from ice cores and tree rings, to develop linkages between climate and the
terrestrial consequences. They have chosen to follow the process theory route in their
studies.
This jump from atmospheric processes to the hydrological consequences completely
ignores observation theory applied to the wealth of readily available data.
Hydrologists have been aware of climate-related anomalies in the hydrological data
for at least half a century. No attempts were made by climate change scientists to
address the causes of these anomalies for the simple reason that they were not aware
of them.
Process theory is fundamentally incapable of producing predictions in a numerical
format required for subsequent analyses. The net result is that climate change
scientists have been unable to produce any believable evidence to support their
alarmist claims. This has a ripple effect. Hydrologists are unable to evaluate and
quantify the changes. Economists are unable to determine the costs and benefits of
preventive or adaptation measures. Political decision makers are unable to make
rational decisions. The whole system fails.
Levels of believability
In law there are generally two levels of proof – balance of probabilities and beyond
reasonable doubt. The seriousness of the whole climate change issue requires
numerical proof at the beyond reasonable doubt level. It must be obvious to any
informed enquirer that the IPCC claims would be beyond reasonable doubt if it could
be shown that there were undeniable, progressive, adverse changes in rainfall and
river flow during historical times that could reasonably be associated with global
warming. It is nowhere near meeting this requirement.
It is axiomatic that any predictions of future climate change require a sound numerical
understanding of current conditions as the point of departure. However this is by no
8
means a simple exercise. Climate is never constant on any time scale from hours
through to thousands of years. As the end product of climate change research has to
be in numerical terms, the logical basis for evaluating changes is from the
commencement of the period of measurement of the consequences of interest. Note
that it is the consequences such as changes in rainfall and river flow that are
important, not changes in the atmospheric and oceanic processes that produce them.
Proof of global warming is not proof of the postulated undesirable consequences.
Climate-related hydrological concerns
The apparently anomalous sequences of above and below average rainfall and river
flow have been known and reported since biblical times. It has been known for more
than 150 years that the drought-related famines in India were frequently broken by
floods. More than 100 years ago Hutchins (1892) reported similar occurrences in
South Africa. I demonstrated it in my 1978 report published by the Department of
Water Affairs, and confirmed the predictability of these occurrences in my 1995 paper
in the SA Journal of Science. As described above, international hydrological literature
is replete with references to the apparently anomalous behaviour of sequences of
hydrological data. The evidence is solid.
Notwithstanding this wealth of information, scientists in the climatological and
environmental sciences frequently claim that any aberration is ‘proof’ of the effects of
global warming. This opportunism has no scientific merit.
Processes of interest
As shown in the above examples from the ancient civilisations of Africa, it is water,
not temperature that determines the habitability of our planet. Furthermore,
temperature is a measure not a property. Temperature does not feature in hydrological
analyses. The principal variables used in hydrological studies are rainfall, river flow
and open water surface evaporation. Their relative values vary greatly from region to
region in South Africa. The claims that global warming will result in the reduction of
the yield of water from dams and the consequent increases in water restrictions are of
no value, until the concurrent effect on the three principal variables and the regional
differences has been demonstrated. No such attempt appears to have been made in the
scientific studies reported in the IPCC literature.
Properties of interest
Climate change studies concentrate on postulated changes in the mean values.
However it is the variability of the hydrological processes that is the fundamental
property of interest. For example, if the flow in a river is constant there is no need to
build storage dams, and the total flow in the river is available for use. The greater the
year-to-year variability, the greater the volume of storage required for a specified
yield. This in turn exposes the stored water to evaporation losses. The highly variable
flows in South African rivers result in the need for large capacity storage dams and
consequent high evaporation losses. These losses account for about 25% reduction in
the potential yield of South African dams.
Outputs of climate change scenarios go no further than postulating changes in the
mean values. For example the claim that the future climate over a region will be drier
and warmer than at present. Even the ancient Egyptians were well aware that it was
not the average annual flows in the Nile River that were important but the sequences
9
of years with below average flows. This was described as the Joseph Effect in the
early hydrological literature. (Mandelbrot and Wallis 1968.) Global climate models
are incapable of providing this essential information.
Database
As climate is the driving mechanism, the data of interest are from the
hydrometeorological processes that are directly driven by climatic processes. A
database of annual values was assembled, consisting of eight different data sets. These
were the South African Weather Service’s (SAWS) district rainfall data from October
1921 to September 1999, plus hydrological data provided by the Department of Water
Affairs and Forestry (DWAF). The DWAF data sets consisted of annual open water
surface (Symons pan) evaporation and concurrent rainfall, annual flows into storage
dams, annual river flows, annual flood peak maxima, annual groundwater levels, and
the southern oscillation index.
Other than patching minor gaps in the records, the data were used directly in the
analyses and were not smoothed, filtered, or otherwise manipulated in any way before
or during the analyses. All sites were chosen on the basis of their geographical
representativeness and long, uninterrupted records. These records are now long
enough to provide a basis for the determination of the multi-decadal properties of the
processes. Details of the database used in the analyses are shown in Table 1.
Table 1. Database used in the analyses
Set
Process
1
Water surface evaporation
20
1180
2
Concurrent rainfall
20
1180
3
District rainfall
93
7141
4
Dam inflow
14
825
5
River flow
14
1052
6
Flood peak maxima
17
1235
7
Groundwater
4
312
8
Southern oscillation index
1
114
183
11 804
TOTAL
Stations
Years
Analytical methodology
All climate-related atmospheric and oceanic processes on all time and space scales
have a mixture of deterministic, predictable components and random, unpredictable
components. In this situation mathematical expressions will only be partially
successful when used for describing the processes. This approximation will be
sufficient in many applications but as the need for greater accuracy and realism
increases, for example in the case of climate change where more subtle consequences
have to be quantified, the deterministic methods will be increasingly suspect.
As the interest is in the consequences of climate change, it follows that the
characteristics must be sought that are common to all hydrometeorological processes
and occur concurrently, and not restricted to the analysis of a single process. While
10
the analyses were based on single site analyses, the interpretations were based on
events that occurred concurrently at most sites and in most processes.
All processes increase in variability with increase in aridity. This has the advantage
that signals related to the extreme events are likely to be more readily detectable in
data from drier regions with more erratic rainfall.
The analytical philosophy used in my studies differed fundamentally from that used in
most climate change studies. The basic assumption was that global warming from
whatever cause, increased progressively but not constantly, during the past century. If
the consequences of global warming are as severe as is generally claimed, then the
consequences should already be observable in hydrometeorological processes of
rainfall, river flow, lake levels, groundwater levels and flood peaks.
Conversely, if changes are not observable, this casts doubts on the postulated adverse
consequences of global warming on the whole range of terrestrial concerns. Change
detection requires a refined numerical knowledge of the hydrometeorological
processes themselves. This in turn requires a thorough practical knowledge of
observation theory and advanced time series analyses. Only when these natural
characteristics have been quantified, will it be possible to detect abnormal changes
that can be attributed to anthropogenic actions.
This should not be too difficult if these consequences are as serious as is generally
claimed by climate change scientists. In the event, it took three years of diligent effort
applied to very large and comprehensive hydrometeorological database to achieve the
required high-resolution numerical characterization of the processes, and the isolation
of the possible effects of global warming.
Results of my analyses
The following is a condensed summary of the results of the study. These are described
more fully in my two published papers (Alexander 2005a and 2005b), and extensively
in my comprehensive technical report now in the final stages of preparation.
(Alexander 2006.)
Open water surface evaporation
The first process of interest within the hydrological cycle is that of evaporation.
Evaporation losses from stored water reduce the yield of storage dams. Evaporation
losses from soils between rainfall events reduce the runoff from subsequent rainfall
events, as the soil moisture deficit has to be satisfied before runoff can occur.
Analyses of open water surface evaporation measurements are also a candidate for the
early detection of the effects of global warming, because open water surface
evaporation is a direct function of incoming solar radiation, (as modified by cloud
cover), air temperature and wind, all at the water surface.
Any change in the hydrological processes resulting from climate change should
become apparent in the evaporation losses well before they become apparent in
rainfall and river flow. This is firstly because of the direct connection between
evaporation and the climatic driving mechanisms, and secondly because of the low
variance in the historical data which would make changes readily apparent. The
analyses indicate that there has indeed been a clearly discernible increase in the
evaporation losses over most of South Africa during the period of record.
11
Fourteen of the 19 accepted stations showed a clearly discernible increase in the mean
values with time. A statistically significant, short duration serial dependence within
the range from one to 13 years was present at all sites. This serial dependence is due
to storage or inertia within the atmospheric system and is not due to cyclical
phenomena. No 21-year periodicity was present in any of the records. The absence
raises some interesting problems that have yet to be resolved.
Rainfall
The South African rainfall database operated by the South African Weather Service
(SAWS) extends back to the middle of the 19th century. A monthly district rainfall
database was established in 1972 (Weather Bureau 1972) based on records from 1921
onwards, and is kept up to date. South Africa was divided into 93 sensibly
homogeneous rainfall districts. The average rainfalls within each district for each
month of record were published. This is the only areal hydrometeorological database
that covers all of South Africa, and is therefore ideal for the determination of rainfall
over the country as a whole. This data set is particularly useful as it overcomes
problems that arise when single station, geographically unrepresentative data are used
for the analyses.
Of particular importance in the analyses was the clearly evident increase in the mean
annual precipitation over virtually the whole of South Africa during the 78-year
period of record. Of the 81 districts with complete records, 75 districts showed an
increase in the mean annual precipitation. Forty-two districts had increases of 10% or
more, 12 districts had increases of more than 20%, and four districts had increases of
more than 40%.
The rainfall in the subsequent two years was well above normal. The most important
conclusion is that there has been a steady, beneficial increase in the mean annual
rainfall over South Africa for at least the past 80 years. The conclusion by the authors
quoted in Tyson & Gatebe (2001), that rainfall over the summer rainfall region of
southern Africa has shown no large systematic linear trends since 1900, is strange, as
there has been an unmistakable and consistent increase in the MAP over virtually the
whole of South Africa since the commencement of district rainfall records. The
conclusions reached by climatologists that are dependent on the assumption of no
historical increase are therefore in error. Assumptions that South African rainfall will
be reduced as a result of global warming are in error in both theory and measurement.
Another important property is the clearly discernible long-term periodicity in the
rainfall data. Eighteen of the districts have statistically significant periodicity within
the range 18 to 21 years; 38 districts exhibit discernible periodicity within this range;
and 37 districts have no discernible periodicity within this range. As the degree of
statistical significance is dependent on both the length of the record and the
magnitude and nature of the variability about the mean, the periodicity may be present
in more of the districts, but has not yet reached a detectable level.
Widespread rainfall
The SAWS daily rainfall data for the period 1910 to 1989 were used in the analyses of
widespread, heavy rainfall. This was from some 2500 rainfall stations. A requirement
was set that the data for each individual station for the specific month had to be
reliable. Rainfall totals for four consecutive days were calculated using daily rainfall
figures. All suspect or unreliable data and accumulated rainfall totals on the record led
12
to the rejection of the station's data for that month. Only stations reporting 100 mm or
more during the month were used in the analysis. Analytical details are provided in
the three-volume report of Alexander and van Heerden (1991).
A total of 6171 widespread rainfall events were identified. These were classified in
terms of their flood-producing potential as shown in Table 2.
Table 2. Widespread severe rainfall
events
Class
Number
of events
Damage
potential
0
4061
Negligible
1
1761
Minor
2
222
3
99
Serious
4
24
Extreme
5
4
Total
Moderate
Disastrous
6171
The annual Nile River floods were beneficial. Their absence was the main concern.
These heavy rains raise the soil-moisture content, sustain crops and natural
vegetation, raise groundwater levels, generate river flow and fill dams. Assume (for
the sake of argument) that global warming increased the frequency of these events by
10%. This would have resulted in an additional 12 potentially damaging floods in the
Class 3 to 5 categories, but an additional 600 beneficial high rainfall events.
The impression created in IPCC literature that global warming will result in an
increase in damaging floods is misleading. An increase in the magnitude and
frequency of heavy rainfall events will be beneficial over most of Africa. Not the
opposite.
Rainfall summary
The mean annual precipitation over almost the whole of South Africa has
progressively increased by at least 9% during the 78-year period of record with a high
degree of assurance. This is similar in magnitude and direction to that quoted by
Gleick (2000) based on a study of a large number of refereed papers in the USA. He
reported that the average precipitation over the contiguous USA has increased by
about 10% since 1910, and that the United States has, on average, warmed by twothirds of a degree Celsius since 1900.
The increase in evaporation from the oceans and terrestrial sources must result in an
increase in global rainfall when the evaporated moisture returns to earth. This leads to
the conclusion that if the present global temperatures continue to rise, then the mean
annual rainfall over South Africa will also continue to increase. Claims that global
warming has in the past, or will in the future, result in a general reduction in the
rainfall over South Africa are without foundation either in fact or in theory.
13
River flow
Routine daily observations of river flow started in the early 1900s. Many records
exceed 80 years in length. Sites were selected on the basis of geographical
representativeness and long, reliable records. They included 12 records of annual
inflows into dams and 14 river flow records at gauged sites.
Of the 26 data sets analysed, six showed increase in the mean annual runoff, 13
showed decreases and seven showed little change. The appreciable utilisation of water
from the catchments, not global warming, is the reason for the observed decreases in
river flow.
Of particular interest in the analyses, was the distinct pattern of reversals from
drought to flood sequences that occurred within a year or two of 1912, 1933, 1954,
1973 and 1995. These years are closely synchronous with the observed 21-year
periodicity. These patterns confirm the observations of Hutchins (1889) and those
reported by Alexander on a number of occasions during recent years. (Alexander
1978, 1994, 1995a, 1995b, 1997, 2002a, 2002b, 2005a and 2005b). There is very
strong evidence of a regular, predicable, periodic pattern of prolonged droughts
suddenly being broken by one or more years of abnormally high runoff. An important
conclusion is that it is essential that estimates of changes resulting from global
warming take these periodic reversals into account.
Flood peak maxima
Data from 16 representative sites were studied. These were part of a much larger data
set consisting of a total of 6 728 years of data from 152 sites that was used for the
statistical analysis of extreme floods. (Alexander 2002b.)
Of the 16 accepted records, 12 showed a decrease in the mean annual values, and only
one record showed an increase. The remaining values were inconclusive. This general
decrease was despite the general increase in rainfall and increase in the numbers of
widespread rainfall events. Upstream utilisation, particularly withdrawals for water
supply and farm dams played a role, as the dams have to fill before passing
floodwaters downstream. Short-term serial dependence was present in eight of the
accepted records, and reversals that were synchronous with sunspot minima were
present in 14 of the 16 records.
An important observation was that the floods of the mid-1800s remain the highest on
record at a number of sites in South Africa. For example, in 1856 the Mgeni River
overflowed its banks and crossed Durban and discharged into the harbour. This has
not happened since then.
Summary of properties
Table 3 summarises the multidecadal properties of the hydrometeorological processes
described above. The presence and absence of these signals and their relative
strengths should provide a valuable insight into the climatic processes and the
hydrometeorological responses.
14
Table 3. Multidecadal properties of hydrometeorological processes
Responses
Year-to-year
variability
Serial
dependence
Long-term
increases
Sudden
periodic
changes
Oscillatory
changes
Evaporation depths
low
very strong
Large
absent
absent
Rainfall depths
moderate
low
Large
present
absent
Groundwater levels
low
strong
Moderate
absent
absent
River flow volumes
high
none
None
strong
absent
very high
none
None
strong
absent
Primary
Secondary
Tertiary
Flood peak maxima
In all, 91% of the rainfall and river flow sites had a discernible periodicity within the
range of 18 to 22 years. At 20% of the sites the periodicity reached the 95% level of
statistical significance. Only 9% of the sites showed no discernible periodicity. This is
a dominant but previously unreported characteristic of the hydrometeorological
processes in South Africa. The concurrent regularity, and therefore predictability of
this periodicity provides a sound basis for the development of a climate prediction
model. (Alexander 2005a.)
While the information in Table 3 is descriptive, it provides valuable and
understandable confirmation of the totally unacceptability of the naïve statements in
the IPCC documentation, which go no further than predicting an increase in the
intensity of the hydrological cycle. This prediction is totally unusable in any
adaptation or amelioration studies.
Linkages with solar activity
Lord Kelvin’s error
Future historians will be interested in the causes of the difficulties currently
experienced in climate change science. They need look no further than Lord Kelvin's
presidential address to the Royal Society in 1892 when he pronounced that there was
no linkage between solar activity and famines in India. This was despite a wealth of
evidence showing a concurrence in time between sunspot activity and the famines.
Lord Kelvin made the mistake that many scientists continue to make. He was entitled
to express an opinion that variations in solar radiation were too small to account for
the linkage between sunspot numbers and famines. He was not entitled to conclude
that no linkage with solar activity existed. This fundamental difference between
process theory and observational theory continues to bedevil climate change science. I
expand on this below.
My studies
Fig. 1 is from my paper Linkages between solar activity and climatic responses
(Alexander 2005b). It shows an undeniable, concurrent linkage between the annual
flows in the Vaal River and solar activity. Pure mathematical-statistical analyses are
inherently incapable of describing this relationship.
15
Figure 1. Comparisons of the characteristics of annual sunspot densities with corresponding
characteristics of the annual flows in the Vaal River.
Starting with the sunspot graphs in Fig. 1, the top panel is the conventional
dimensionless histogram, where all values are expressed as multiples of the record
mean values. The 21-year periodicity is apparent. A reference datum value of –200
was used in order to accommodate the negative values. This has no effect on the
interpretations.
The most informative graphical presentation is in the second panel, which shows the
accumulated departures from the record mean value. These are obtained by
subtracting the mean values (1.0) from each of the values in the histogram. Some of
the values will be negative. These are accumulated one at a time and the sum plotted.
A steady increase in the accumulated departures of the sunspot numbers during the
period of record is immediately apparent. This is in accordance with observations of
an increase in solar activity during the past century as shown by the increases in
sunspot density. This and not anthropogenic activities is the probable cause of a
corresponding increase in global warming and the hydrological characteristics
discussed in this chapter. This possibility should not be overlooked.
The maximum negative departures occur at the start of the 21-year periods, identified
as (A), (C), (E) and (G). The third panel is the correlogram. This is a standard
calculation procedure in time series analyses. The statistically significant cyclicity is
clearly apparent. The 95% confidence limits are ± 0.22. The minimum and maximum
(H) autocorrelation coefficients occur respectively at 10 (-0.83) and 21 (+0.70) years,
which are well in excess of the 95% confidence limits.
Now compare the annual flows in the Vaal River with the sunspot density
characteristics. The histogram shows the high degree of asymmetry about the mean
16
value with many more values less than the mean value than above it. This is typical of
river flow data in dry climates.
The accumulated departure plot and its comparison with that of the double sunspot
cycle are very instructive. The reversals at points (A), (C), (E) and (G) are virtually
identical with the corresponding reversals in the sunspot data. They occurred during
the hydrological years beginning October 1933, 1954, 1973, and 1995. The rising
limbs A-B, C-D and E-F are sequences of years where the inflows were greater than
the mean value. The falling limbs B-C, D-E, and F-G are sequences where the inflows
were less than the mean value. These alternating sequences are well known in the
hydrological literature where they are referred to as the Joseph effect, after Joseph’s
biblical prophecy.
The statistically significant cyclicity in the sunspot cycles is no longer present in the
correlogram of the annual flows in the Vaal River, where the residual coefficients
indicate random noise. The only, but very important, residual serial correlation, is the
statistically significant 21-year periodicity. This is identified at (H) in the bottom
panel of the figure.
Successful predictions
The ultimate test of any prediction model is its successful predictions. My climate
prediction model is based on the regular, predicable periodicity in the South African
hydrometeorological data. In my paper Floods, droughts and climate change
published in August 1995, (Alexander 1995), I predicted that drought-breaking floods
were imminent. Severe floods over Southern Africa commenced three months after
publication and continued through to the rest of the season.
A severe drought occurred over wide areas of South Africa during the period
subsequent to 2001. In November 2005 I issued a flood alert that there was a 75%
probability of severe widespread rainfall occurring before the end of the summer
rainfall season. During the first week of January 2006 heavy, drought-breaking rains
occurred over wide areas of southern Africa. Flood gates of Grootdraai Dam on the
Vaal River had to be opened and parts of the town of Standerton downstream of the
dam had to be evacuated. This is part of the Vaal River catchment illustrated in Fig. 1.
At the time of writing, there are another three months to go before the end of the
summer season.
I believe that my prediction model based on the observed periodicity of South African
hydrometeorological data is at least as reliable as seasonal predictions by
climatologists based on global climate models. Climate change advocates are
reluctant to accept this method as it demonstrates multi-year properties that are
completely ignored in their predictions. This is illustrated in the following extract
from the principal IPCC publication.
IPCC’s view
The following view was expressed in the IPCC’s Summary for Policymakers (IPCC
2001).
Since the late 1970s, satellite instruments have observed small oscillations due
to the 11-year solar cycle. Mechanisms for the amplification of solar effects on
climate have been proposed, but currently lack a rigorous theoretical or
observational basis.
17
This statement is careless from the start as the average length of the sunspot cycles
during the past century was 10.4 years, not 11 years. In 1889 Hutchins published a
very perceptive and well-documented linkage between solar activity and climaterelated responses. (Hutchins 1889). This linkage was repudiated by many eminent
solar physicists, who for the past hundred years have maintained, and still maintain,
that these correlations lack causal mechanisms supported by high quality data.
My studies demonstrated an unambiguous, concurrent linkage with a high degree of
confidence, based on a detailed study of a very large climate-related database.
Hopefully, the information provided here will assist solar physicists to review their
position. They should attempt to identify the specific characteristics of the solar
processes that cause these climatic features that have been noted and documented for
more than a thousand years.
Mathematical modelling
The final stage of my studies was the development of a mathematical simulation
model for water resource development and management applications that
accommodated the multi-year characteristics described above. There was no need to
invoke causal linkages with solar activity in the model, as the analyses do not depend
on them. The methodology is described in Alexander, (1994, 1997 and 2005a).
Conclusions
There is a large station-to-station variability in the hydrometeorological records, and
care has to be exercised when interpreting individual analyses. Nevertheless, there are
strong and unambiguous signals that are common to most graphical and statistical
analyses within each process and between processes. The following are some
important observations and interpretations generated by my study.
General
1.
Year-to-year variability of the hydrometeorological processes increases
greatly from evaporation, to rainfall, to river flow, to flood peak maxima. This
increasing variability in the secondary and tertiary processes progressively
overwhelms other changes that may be present, but are not detectable. They also
increasingly filter out the smaller events.
2.
Open water surface evaporation is a direct function of solar radiation and air
temperature. The random components were close to zero.
3.
The soil-moisture deficit has to be satisfied before runoff can occur. This is a
function of evaporation losses between rainfall events. River flow is therefore a
function of both rainfall and antecedent evaporation and is not a function of rainfall
alone. This is the situation over most of Africa outside the tropics.
Statistical properties
4.
The mean annual precipitation over almost the whole of South Africa has
progressively increased by at least 9% during the 78-year period of record with a high
degree of assurance. There is some indication of an acceleration in the rate of increase
in the last two decades. This conclusion is reinforced by the concurrent increase in
open water surface evaporation in South Africa, which is a direct function of
incoming solar radiation and air temperature. This leads to the conclusion that any
additional global warming will further increase the annual rainfall over South Africa.
18
The possibility that it will decrease the rainfall in the foreseeable future is remote and
without scientific merit.
5.
Short-term serial dependence (less than 10 years) is present in many records. It
is a result of storage and inertia in the hydrometeorological processes. These may be
due to high storage/input ratios, or natural thermal or mechanical inertia of climatic or
oceanic processes. There was no evidence that this could be due to oscillatory
behaviour of the causative mechanisms.
6.
There is very strong evidence of long term periodicity (18 to 22 years) in
annual rainfall and river flows. The reversals took place within a year or two of 1912,
1933, 1954, 1973, and 1995 that identify the commencement of the 21-year periods. It
is characterised by sudden, statistically significant, predictable, periodic reversals
from sequences of years of prolonged droughts, to sequences of years of high rainfall
and river flow. The most likely cause seems to be that the poleward transfer of solar
energy amplifies the systematic irregularities in the solar energy processes. As far as I
know the periodic climate reversals have not been reported by international stochastic
hydrologists or atmospheric scientists, although they were reported in South Africa
more than a hundred years ago, and I reported them on several occasions during the
past 25 years.
Extreme floods
7.
The statistical properties of widespread, severe floods are described in detail in
Alexander (2002b). The properties of extreme, flood-producing rainfall in South
Africa are independent of geographical location, mean annual rainfall, or rainfall
seasonality. Furthermore, extreme floods are the result of weather systems that are not
annual events at any one site. The depth-area-duration-frequency properties of
widespread, severe flood-producing rainfall generated by cut-off lows in the southwestern Cape, are not measurably distinguishable from those generated by tropical
cyclones in the northern regions of South Africa. My studies demonstrated that the
occurrence of these floods has a periodic pattern associated with characteristic
reversals from droughts to floods.
8.
At a number of sites in South Africa, floods experienced in the mid-1800s
remain the highest on record. An analysis of the ranked values at all sites showed that
there was no discernible, continuous change with time. This information has to be
borne in mind when assessing the effect of climate change on frequency and
magnitude of severe floods.
9.
High losses of life and damage to property in South Africa and elsewhere in
the world in recent years were primarily the consequence of rising populations and the
associated unavoidable occupation of flood-prone areas. These were worsened by
socio-economic conditions and were not the result of increases in flood magnitude or
frequency. (Alexander 1999.) For this reason, increases in insurance payments in
recent years cannot be used as indicators of increases in the magnitude and frequency
of floods.
Extreme droughts
10.
It is not sufficient to predict increases in the severity of floods and droughts
based on an assumed increase in the variability of atmospheric processes. Floods and
droughts are altogether different and unrelated hydrological phenomena. Floods have
durations measured in days and are embedded within annual river flows. They can
therefore be modelled as annual events. In contrast, droughts are multi-year
19
phenomena and are not simply combinations of independent annual occurrences. The
degree of serial dependence of the annual values plays a dominant role in the duration
of droughts, and therefore their magnitudes. Predictions of increases in the magnitude
and frequency of droughts will remain suspect until the serial dependence structure
has been determined, and changes in this structure have been demonstrated.
11.
The multi-year periods of below average river flow will have an appreciable
detrimental effect on the calculated assurance of the yield of storage dams if they are
not taken into account in the yield-capacity analyses. The multi-year negative
departure from the long-term mean annual precipitation associated with this
periodicity, is the direct cause of prolonged historical droughts. There is no evidence
to support a postulated increase in the magnitude and severity of these droughts in
recent years. It is not the droughts that are becoming progressively more extreme, but
the socio-economic conditions of the poor communities that depend on the natural
environment for their survival. (Alexander 1999.)
Finally
12.
The oscillatory characteristics reported in the climatological literature are not
present in the hydrometeorological data. They are artefacts of the spectral analysis
methods used in the analyses.
13.
The serial dependence, periodicity and the abnormalities in the behaviour of
the mean reported in this presentation should provide valuable information on
linkages between climatic and hydrometeorological processes. Conversely, if no such
linkages are found, it is most unlikely that it will be possible to provide credible
relationships between climate change scenarios and hydrometeorological responses.
14.
There was no evidence in the analyses to support the view that climate change
will result in meaningful increases in the frequency and severity of floods and
droughts within the next 50 years. All evidence was to the contrary.
15.
Climatologists who rely solely on IPCC scenarios and peer-reviewed
publications, and ignore the many comprehensive, publicly available documents, are
walking blindfold into a lion’s den. There is very much more information that is
relevant to the effects of climate on the environment, agriculture and water resources
in government reports, training manuals and codes of practice than in academic
research papers in refereed journals.
16.
For the last 30 years there have been repeated claims by climate change
advocates that climate change will result in the destruction of natural vegetation and
consequent desertification of large areas of South Africa. These were taken seriously
at the time and commissions of enquiry consisting of experienced scientists were
appointed by the government to investigate the predictions. Their conclusions were
that there was no foundation for the allegations. Recently climate change scientists
have repeated their predictions of future degradation of the natural environment
resulting from global warming, based on the assumption that future climate will be
warmer and drier. This alarmist view is doubly in error. The first is that rainfall is
increasing not decreasing. The second is that the predicted increases in temperature
are no more than the increase between dawn and midday. It is ridiculous to postulate
that the natural vegetation over large regions of South Africa will be destroyed by the
predicted change in temperature that the natural vegetation experiences every day of
the year.
20
17.
My studies have enabled me to develop a multi-year climate prediction model
that is sufficiently accurate for long-term planning purposes.
18.
The tactics used by climate change advocates to advance their cause are
clearly unsubstantiated, unscientific and unethical.
The final nail?
19.
Recent statements by climate change scientists have given great prominence to
claims that global temperatures have risen to unprecedented levels and that is proof of
anthropogenic causes of climate change. However, proof of global warming is not
proof of the proclaimed consequences. Although the 1990s were reported to be the
warmest decade of the millennium, this was not reflected in an unusual increase in the
numbers and magnitudes of exceptional hydrological events in South Africa. More
recently, the 2005 global temperatures were proclaimed to be higher than any in the
recent geological past. Again, no exceptional rainfalls, river flows, floods or droughts
occurred during the year. This clearly supports my findings described in this
presentation that there is no observable linkage between increases in global warming
from whatever cause, and changes in the hydrometeorological processes. The
evidence is solid and incontestable.
The road ahead
The problem that now confronts climate change scientists is that advanced data
analyses do not support their theories. The IPCC should have sought expert advice on
numerical analyses based on observation theory, before issuing unfounded statements
that have caused a great deal of alarm to people and the nations of the world, divided
scientists, and produced scepticism in the eyes of experts in the affected fields.
The consequence, as shown in my studies, is that South African climate change
scientists do not possess the skills required for evaluation, prediction and adaptation
studies. They will no doubt continue to deride all those who hold opposing views, and
will deliberately obstruct efforts directed towards finding workable solutions to this
very difficult problem. The people of South Africa will suffer as a result of this
unscientific and unpatriotic policy.
I encountered many difficulties during these studies in my attempts to communicate
my progress and results to interested parties, organisations and some scientific
publications. This is not the place to list my woes, so I conclude with this passage
from The Declaration of Science and the Use of Scientific Knowledge produced by the
World Conference on Science held in Budapest, Hungary in June 1999 under the
aegis of the United Nations Educational, Scientific and Cultural Organisation
(UNESCO) and the International Council for Science (ICSU).
Greater interdisciplinary efforts, involving both natural and social sciences,
are a prerequisite for dealing with ethical, social, cultural, environmental,
gender, economic and health issues…What distinguishes the poor (be it
people or countries) from the rich is not only that they have fewer assets, but
also that they are largely excluded from the creation and the benefits of
scientific knowledge…the future of humankind will become more dependent
on the equitable production, distribution and use of knowledge than ever
before
This has been my objective throughout my entire professional career.
21
Acknowledgments
The provision of the data by the Department of Water Affairs and Forestry as well as
the South African Weather Service is gratefully acknowledged. I greatly value the
moral support and encouragement from professional colleagues without which I
would have thrown in the towel long ago. I also believe that I received spiritual
guidance on occasion.
References
This is a list of publications referred to in this chapter with emphasis on my own
contributions. It is not an exhaustive list of relevant publications on this subject.
Alexander, W.J.R., 1978. Long range prediction of river flow - a preliminary
assessment. Department of Water Affairs Technical Report TR 80. This was the
predecessor of a number of subsequent publications on this subject, right up to my
current studies.
Alexander, W.J.R., 1985. The hydrology of low latitude Southern Hemisphere land
masses. In: Hydrobiologia, ed Davies & Walmsley, Junk Publishers, Holland. This is
an overview of the hydrometeorological processes and their geographical variability.
Alexander, W.J.R. and van Heerden. J., 1991. Determination of the risk of widespread
interruption of communications due to floods. Research Project Nr RDAC 90/16. This
comprehensive three-volume report commissioned by the Department of Transport
contains a wealth of previously unpublished information on widespread, severe
rainfall events. It is the presence or absence of these events that results in flood or
drought conditions respectively.
Alexander W.J.R., 1994. Anomalies in the stochastic properties of river flow and their
effect on reservoir yield. Proceedings, Republic of China-South Africa Bilateral
Symposium, Taipeh, Taiwan.
Alexander W.J.R., 1995a. Detection of climate change. Proceedings, IGBP
Conference on Global Environmental Change – Implications for Southern Africa.
Pretoria.
Alexander W.J.R., 1995b. Floods, droughts and climate change. S Afr J Sci 91, 403408. August 1995. I successfully predicted that imminent floods would occur and
break the then current drought.
Alexander W.J.R., 1997. Predictability of widespread, severe droughts, and their
effect on water resource management. Proceedings, 5th International conference on
southern hemisphere meteorology and oceanography. Invited guest presentation.
Alexander W.J.R., 1999. Risk and society – an African perspective. United Nations
IDNDR commissioned study. Geneva, Switzerland.
Alexander W.J.R., 2002a. Climate change – the missing links. Science in Africa.
September 2002.
Alexander W.J.R., 2002b. Statistical analysis of extreme floods. J S Afr Instn Civ
Engg, 44 (1) 2002 20-25.
Alexander W.J.R., 2004. Climate change – there is no need for concern. Science in
Africa April 2004.
22
Alexander W.J.R., 2005a. Development of a multi-year climate prediction model.
Water SA 31(2), www.wrc.org.za/downloads/watersa/205/Apr-05/1788.pdf.
Alexander W.J.R., 2005b. Linkages between solar activity and climatic responses.
Energy & Environment, 16(2),
www.ingentaconnect.com/content/mscp/ene/2005/00000016/00000002/art00003.
Alexander W.J.R., 2006. An assessment of the likely consequences of global warming
on the climate of South Africa. Technical report in preparation.
Biswas A.K., History of hydrology. North-Holland Publishing Company, Amsterdam.
Gleick P. H., 2000. Water: The potential consequences of climate variability and
change for the water resources of the United States. U.S. Department of the Interior.
Hutchins D.E., 1889. Cycles of drought and good seasons in South Africa. Wynberg
Times Steam Printing Office. Wynberg. Privately published. Hutchins displayed an
insight into fundamental climatological processes that seems to have been lost by
many modern authors and researchers.
Klemes V., 1974. The Hurst phenomenon: a puzzle? Water Resources Research Vol.
10 No 4, August 1974.
Kokot D.F., 1948. An investigation into the evidence bearing on recent climatic
changes over southern Africa. Irrigation Department Memoir. This is a
comprehensive study in which he found no evidence to support the view that climatic
changes had reduced rainfall.
Mandelbrot B.B. and Wallis J.R. 1968. Noah, Joseph and operational hydrology.
Water Resources Research Vol. 4 No 5, October 1968.
Tyson P.D. and Gatebe C.K. 2001. The atmosphere, aerosols, trace gasses and
biogeochemical change in southern Africa: a regional integration. S Afr J Sc 97, 106118.
Van der Merwe C.R., Acocks J.P.H., Brain C.K., Frommurze H.F., Kokot D.F.,
Schumann T.E.W., and Tidmarsh C.E.M., 1951. Report of the Desert Encroachment
Committee appointed by the Minister of Agriculture. Government Printer (U.G.
59/1951). This is a thorough multidisciplinary report by a team of South Africa’s
leading scientists. They concluded that there had been no decrease in rainfall over
South Africa.
Wallis J.R., and O’Connell, 1973. Firm reservoir yield. How reliable are historic
hydrological records? IBM Research R64298.
Wallis J.R., and Matalas, 1971. Correlogram analysis revisited. Water Resources
Research Vol 7 No 6, December 1971.
Weather Bureau 1972. In Climate of South Africa: Part 10, District Rainfall and the
annual march of rainfall over Southern Africa, WB 35, Pretoria
Yevjevich V. 1968. Miscoceptions in hydrology and their consequences. Water
Resources Research Vol. 4 No 2, April 1968.
Yevjevich V. 1972. Stochastic processes in hydrology. Water Resources Publications,
Fort Collins, Colorado USA.
23
TOC
The issues ...................................................................................................................... 1
The birth of early civilisations in Africa ................................................................ 3
3000 years of hydrological observations ............................................................... 3
Early South African studies ................................................................................... 6
Clash of theories ........................................................................................................... 7
Levels of believability............................................................................................ 7
Climate-related hydrological concerns ...................................................................... 8
Processes of interest ............................................................................................... 8
Properties of interest .............................................................................................. 8
Database ................................................................................................................. 9
Analytical methodology ............................................................................................... 9
Results of my analyses ............................................................................................... 10
Open water surface evaporation........................................................................... 10
Rainfall ................................................................................................................. 11
Widespread rainfall .............................................................................................. 11
Rainfall summary ................................................................................................. 12
River flow ............................................................................................................ 13
Flood peak maxima .............................................................................................. 13
Summary of properties ......................................................................................... 13
Linkages with solar activity ...................................................................................... 14
Lord Kelvin’s error .............................................................................................. 14
My studies ............................................................................................................ 14
Successful predictions .......................................................................................... 16
IPCC’s view ......................................................................................................... 16
Mathematical modelling ...................................................................................... 17
Conclusions ................................................................................................................. 17
The road ahead........................................................................................................... 20
Acknowledgments................................................................................................ 21
References ............................................................................................................ 21
[10 517 words]