Abstract

Keywords

Climate crises; sea level rise; coastal property; coastal accretion; coastal erosion; integrated coastal management.

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1 Introduction

In modern South African law there are several methods in terms of which a person may acquire ownership of a thing. These methods are usually divided into two broad categories, namely the original methods of acquiring ownership and the derivative methods of acquiring ownership. The acquisition of ownership is original if it is acquired in terms of a unilateral act and is not derived from the ownership of a predecessor-in-title. In other words, if there is no transfer of the right of ownership from a predecessor-in-title to a successor-in-title. Instead, an entirely new right of ownership is created by the operation of law in respect of the thing. At the same time, any previously existing rights of ownership are extinguished by operation of law.1

One of the original methods of acquiring ownership is accession (accessio).2 Ownership is acquired by accession when one thing is incorporated by natural or artificial means into another thing in such a way that a new composite entity is created. In terms of this process, one thing loses its physical or economic independence and becomes a part of the other thing. The thing that loses its independence is classified as the accessory thing, while the thing that retains its independence is classified as the principal thing. An important consequence of this classification is that

the owner of the principal thing becomes the owner of the new composite entity and the owner of the accessory thing loses his or her ownership.3

The acquisition of ownership by accession has traditionally been divided into three categories, namely natural accession (accessio naturalis), industrial accession (accessio industrialis) and mixed accession (accessio mixta). In modern South African law, however, the acquisition of ownership by accession is more commonly divided into the accession of immovables to immovables, movables to movables and movables to immovables. Unlike the traditional classification, this modern classification is based not on the process by which one thing is incorporated into another thing (natural, industrial or mixed) but rather on the nature of the things themselves (movable or immovable).4

The accession of immovables to immovables itself is divided into different categories, one of which is alluvion or alluvio.5 Alluvion is defined in South African law as:

the gradual and imperceptible increase of land by soil being deposited by the action of a river or the sea. This increase can consist either in the addition of geological substances (sand, silt and mud) to the river bank or in an increase in the acreage of the land.6

Alluvion thus applies to land bounded by water, including tidal water, and governs the location of the boundary between land and water, when the location of the boundary water changes. As Corkill points out, however, these principles might have remained as "obscure, arcane elements of property law of little interest to most lawyers and policymakers" were it not for the fact that the global climate crisis, and in particular higher sea levels, "will inevitably change the location of the interface between land and tidal waters, adversely affecting many coastal settlements."7

Although Corkill was referring to the situation in Australia, his point applies with equal force to South Africa. This is borne out by the fact that the change in the "location of the interface between land and tidal waters" that will inevitably be brought about by higher sea levels has already caught the attention of lawyers and policymakers in South Africa and has been translated into legislation that extends the application of the common law principles governing the acquisition of land by alluvion and its opposite (the loss of land by erosion) so that they encompass not only non-delimited coastal land (agri non-limitati) but also delimited coastal land (agri limitati).

These statutory provisions may be found in section 14(5) of the National Environmental Management: Integrated Coastal Management Act (the NEM: ICMA),8 which reads as follows:

If the highwater mark is landward of a straight line boundary of a coastal land unit when this Act took effect, or the highwater mark moves landward of a straight line boundary of a coastal land unit due to the erosion of the coast, sea level rise or other causes, the owner of that coastal land unit:

(a) loses ownership of any portion of that coastal land unit that is situated below the highwater mark to the extent that such land unit becomes coastal public property; and

(b) is not entitled to compensation from the State for that loss of ownership, unless the movement of the highwater mark was caused by an intentional or negligent act or omission by an organ of state and was a reasonably foreseeable consequence of that act or omission.

The purpose of this article, therefore, is to investigate the manner in which these provisions have extended the application of the common law principles governing the acquisition and loss of ownership of coastal land

by alluvion and erosion respectively to include both agri non limitati and agri limitati. Before turning to consider these provisions in more detail, however, it may be helpful to discuss the nature and consequences of climate-change-induced rising sea levels, especially for South Africa, as well as the common law principles governing the acquisition and loss of ownership of land because of alluvion and erosion.

2 Sea level rise

Although the global mean sea level9 has been rising since the end of the last great ice age 23 000 years ago, one of the most noticeable effects of the increase in global temperatures since the end of the 19th century is that the rate at which the global mean sea level is rising has accelerated and will continue to do so over the next century and possibly beyond that.10

In its Climate Change 2023: Synthesis Report – A Summary for Policy Makers, the United Nations Intergovernmental Panel on Climate Change (the IPCC)11 states that between 1901 and 2018 the global mean sea level increased by 20cm and that the rate of increase has accelerated significantly over the same period of time. Between 2006 and 2017 the global mean sea level increased at a rate of 3.7mm per annum. This is nearly twice as fast as the rate of increase between 1971 and 2006 (1.9mm per annum) and nearly three times as fast as the rate of increase between 1901 and 1971 (1.3mm per annum). It is very likely, the IPCC goes on to state, that the main driver of these rapid increases is human activity, at least since 1971.12

Irrespective of any measures that may be adopted to reduce Green House Gas (GHG) emissions now or in the near term, the IPCC states further, the global mean sea level will continue to increase for centuries to come and sea levels will remain elevated for thousands of years due to the thermal expansion of the ocean and the melting of glaciers and ice sheets, both of

which have centuries-long time lags.13 Under a very low GHG emissions scenario (SSP1-1.9), the IPCC asserts further, the global mean sea level will in all likelihood rise between 15 and 23cm by 2050 and between 28 and 55cm by 2100. Under a high GHG emissions scenario (SSP5-8.5), sea levels will rise between 20 and 29cm by 2050 and 63cm and 1 meter by 2100.14

As a result of the unavoidable increase in global mean sea levels, the IPCC warns that the risks of coastal flooding, coastal erosion and saltwater intrusion are very likely to significantly increase along all low-lying coasts up to and beyond 2100.15 It also warns that "current 1-in-100 year extreme sea level events" that were historically rare will become more common and "occur at least annually in more than half of all tide gauge locations by 2100" under all of the SSP scenarios.16

It is important to note that while changes in the global mean sea level are primarily driven by thermal expansion of the ocean as it becomes warmer, the increased melting of land-based ice from glaciers and ice sheets (especially in Antarctica and Greenland) and changes in land water storage, changes in relative mean sea levels are driven by a wider range of local factors. These include ocean currents, variations in land height, vertical land motion and upstream flood control. An important consequence is that the rate at which the level of the sea is increasing is not the same across the

entire globe. Instead, the rate at which the level of the sea is increasing at specific locations may be larger or smaller than the global average.17

As a recent study by Allison et al. illustrates, this is certainly the case insofar as South Africa is concerned.18 Relying on data taken from tidal gauge records and satellite altimetry datasets, the study projects that under a low emissions scenario, sea levels around South Africa will increase between 50 and 80 cm and under a high emissions scenario between 50 cm and 1.4 m by 2100. These increases are larger than those projected for global mean sea level rise.19

These increases will undoubtedly have a dramatic effect on the South African coast for at least three reasons:20

A wide range of strategies may be adopted in order to ameliorate these negative consequences. Amongst these are hard engineering options, soft engineering options and socio-institutional options. Hard engineering options include sea walls; groynes, barrages; raising infrastructure, beach nourishment and replenishment, water pumps and beach drainage. Soft engineering options include dune cordons, coastal mangroves, estuary and wetland rehabilitation and kelp beds. Socio-institutional options include vulnerability mapping, risk communication, coastal set-back lines, early warning systems and managed retreats.21 While these strategies may ameliorate some of the negative consequences associated with sea level

rise, it is very unlikely that any of them will be able to prevent a change in the location of littoral boundaries and, consequently, a change in the property rights of littoral owners.

Having briefly discussed the nature and consequences of climate-change-induced sea level rise, especially for South Africa, we can now turn to discussing the common law principles governing the acquisition and loss of the ownership of land as a result of alluvion and erosion from a legal-historical perspective beginning with Roman law.

3 Roman law

The concept of alluvion may be traced back to Roman law and, in particular, to the works of Gaius. In the second book of his Institutes of Roman Law, for example, Gaius describes the concept in the following terms:

Alluvial accretions to our land become ours, again by natural law. That is held to be accretion by alluvion which a river adds to our land so gradually that it is impossible to estimate how much is being added at any particular moment; whence the common saying, that an addition is by alluvion if it is so gradual as to be invisible.22

And, in the second book of his Common Matters or Golden Rules, Gaius describes alluvion in similar terms, although more briefly:

Furthermore, what the river adds to our land by alluvion becomes ours by the law of nations. Addition by alluvion is that which is gradually added so that we cannot, at any given time, discern what is added.23

As these definitions illustrate, rivers were the central cause of alluvion in Roman law. Insofar as rivers were concerned Roman law distinguished inter alia between rivers (flumen) and streams (rivus) and between public rivers and private rivers. A river was distinguished from a stream on the basis of its size or the opinion of those living in the neighbourhood and a public river was distinguished from a private river on the basis of whether it had a perennial flow or not.24 A public river, therefore, was one that was perennial and was large enough to be considered a river and not a stream.

In the sixty-eighth book of his Edicts, for example, Ulpian says that "[a] river is to be distinguished from a stream by its size and by the opinion of the surrounding inhabitants"25 and that "some rivers are public, some not".26 A public river, he goes on to state, was defined by the Sabinian jurist Cassius "as a perennial one" and that "this opinion of Cassius, which Celsus also approves, is held to be acceptable."27

These distinctions were important because public rivers and their banks were classified as public things (res publicae)28 and as such were not considered to be the private property of any individual person, but rather as "the property of the community itself"29 or, as Ulpian put it, they were considered to be the property of the "Roman people".30

Although public rivers were considered to be the property of the whole community, in his commentary on the Institutes of Justinian Vinnius points out that the bed and the banks of a public river bounded by private land were regarded as public only in the sense that the public was entitled to use them as a necessary incident of using the river itself. The ownership of the bed and the banks was vested in the riparian owner and he or she therefore was entitled to claim the alluvion. The same principles also applied when a public river changed course and its bed dried up or when an island was formed in a public river.31

In other words, a riparian landowner's right to claim alluvion or ownership of a dry public river bed or ownership of an island that arose in a public river

was based on the principle that while the community was entitled to use and enjoy a public river, it did not own the bed or the banks of that river. Instead, the bed and the banks of a public river were owned by the riparian owners. This principle was referred to by the Appellate Division (as it then was) in Van Niekerk and Union Government (Minister of Lands) v Cater,32 where Solomon JA made the following points:

It is true that as regards public rivers generally it is laid down in the Institutes, 2.1.2, and in the Digest, 43.12.1.7, that, if a river leaves its bed and forms another course, the new bed although it may have been private land before becomes public; the reason given being that 'it is impossible that the channel of a public stream should not be public'. But it seems clear that in these passages the word 'public' is used, not in the sense of the property of the State, but in the sense that its use is public or common to all as is that of the flowing water itself. That is the meaning which is given to these passages by Vinnius on Institutes (2.1.4.23), and his reasoning appears conclusive. That the bed of a public river was not necessarily regarded as the property of the State seems clear from the rule of Roman law that 'if a river forsakes its natural channel, and flows in another direction, the old bed of the river is the property of those who own the adjoining banks'. Institutes, 2.1.23. So also, if an island is formed in the middle of the bed of a river each of the riparian proprietors becomes the owner of half the island, but if it should be nearer to one bank than to the other, it is the property of that one of the riparian proprietors on whose side it happens to be, Institutes, 2.1.22. These doctrines of the Roman law which are adopted by the Roman-Dutch authorities are only intelligible on the principle that the bed of a river is presumed to be the property of those who own the adjoining land, which is taken to extend on each side to the middle of the stream.33

Apart from defining what is meant by alluvion, two other important points emerge from Roman law. The first of these is that the right to claim alluvion does not apply to lakes or pools,34 although no mention is made of the sea,35 and the second is that the right to claim alluvion does not apply to agri limitati.36 Agri limitati are plots of land that are enclosed on all sides by surveyed lines and other artificial boundaries, even though they may border on a natural feature such as a public river or the seashore. Agri limitati are usually distinguished from agri non limitati which are plots of land that have one or more natural boundaries such as a public river or the seashore.37

The difference between agri limitati and an agri non limitati was highlighted by the Appellate Division in Van Niekerk, where Innes CJ held as follows:

Agri limitati were lands granted by the State to private individuals and defined by artificial boundaries, such as pillars and posts, walls, mounds, etc. They were carefully surveyed and demarcated; but their distinctive feature was that their limits were not natural but artificial. A field bounded by a river, and following all the sinuosities of its course was not an ager limitatus; a field bounded by lines between beacons, however near those lines approximated to the bank, was an ager limitatus .... And the owner of such a property was confined within the strict limits demarcated upon the ground ...38

A slightly more concise distinction was drawn by the Natal Provincial Division of the Supreme Court (as it then was) in Durban City Council v Minister of Agriculture,39 where Didcott J held as follows:

An ager limitatus is a plot of land enclosed on all sides by artificial boundaries and demarcated as such. An ager non limitatus is a plot bounded on one side or more by some natural feature, a river or the seashore for instance. Irrespective of the sort of boundaries it has, a plot defined by measurement is also an ager limitatus or, if not one in the pure sense then tantamount at least to such and so to be regarded for all practical purposes.40

Finally, it is also important to note that the Roman jurists distinguished between the acquisition of ownership by means of alluvion and the acquisition of ownership by means of avulsion (avulsio). Unlike alluvion, avulsion is the sudden and noticeable addition of soil to land as a result of the violent actions of a public and non-navigable river. This method of acquiring ownership is described by Gaius, once again in the second book of his Common Matters or Golden Rules, as follows:

But if the force of the river should detach part of your land and bring it down to mine, it obviously remains yours. Of course, if it adheres to my land, over a period of time, and trees on it thrust their roots into my land, it is deemed from that time to have become part of my land.41

As this passage clearly indicates, the second landowner acquires ownership of the detached portion only after it has become firmly attached to his or her land, for example when plants take root. There are consequently three stages to avulsion: first, the sudden natural disannexation of a piece of land; second, the natural deposit of that piece of land on another; and, third, the process by which that piece of land is annexed to the piece on which it was deposited.

The key differences between alluvion and avulsion, therefore, are as follows:

4 Roman-Dutch law

Unlike the situation in Roman law, the acquisition of ownership by alluvion gave rise to difficult issues in Roman-Dutch law. Perhaps the most important of these was whether private landowners retained the right to claim alluvion in terms of Roman-Dutch law, at least in so far as public rivers were concerned. Some Roman-Dutch jurists argued that private landowners did retain this right, while others argued that they did not.

Those jurists who argued that private landowners did not retain the right to claim alluvion in terms of Roman-Dutch law based their argument on the fact that in Roman-Dutch law public rivers did not belong to the people, but rather to the Sovereign as one of his minor regalian rights (the regalia minora).42 Given that public rivers belonged to the Sovereign, they argued

further, it was the Sovereign, and not the private landowner, who was entitled to claim alluvion.43

This argument was made by Groenewegen, among others, who put it as follows:

But as nowadays public rivers are ascribed to the ownership of the Sovereign and constitute Crown [regalian] property … it follows of necessity that by present day custom alluvion and other accretions forming in rivers belong to the Sovereign or to those who enjoy a right in them granted by the Sovereign. On this matter there exists a Placaat of Phillip II, Sovereign of Spain and of us, of 22 May 1559, in which it is provided that no one may claim fishing rights, alluvion or other accretions in rivers, unless he has obtained the consent of his Majesty after having established lawful title thereto in the Exchequer Department or having otherwise proved his right thereto.44

This approach was rejected by Voet, who argued that while it was true that King Phillip II appeared to have claimed all rights in alluvion for himself, this claim was confined to agri limitati only. Insofar as agri non limitati were concerned, he argued further, "there is no doubt that the benefits of alluvion accrue to the owners of such lands, so that they can also advance this right of alluvion for their own benefit in their own right and at their own expense by erecting dams in the river, by planting, by fortifying the bank and by other methods, provided that they do not obstruct navigation or any right which has accrued to others."45

Like Voet, De Groot also distinguished between agri limitati and agri non limitati. Insofar as agri limitati were concerned, he accepted that the right to alluvion vested in the Sovereign. He stated in this respect that "[o]ne thing is certain, that in lands which are granted out by the Count by certain metes and bounds the alluvion outside the said limits belongs to the Count."46 When it came to agri non limitati, however, De Groot did not take a firm stand. Instead he argued that the legal position was uncertain, largely because it was based on local customs and decisions that differed from place to place. The lack of legal certainty, he pointed out, was clearly illustrated in Holland and West Friesland where the Count argued that alluvion belonged to him "as a consequence of the water", but that "[others

denied] this, and what must be taken to be law in regard to this matter is in view of the variety of customs and decisions very uncertain."47

5 South African common law

Despite the fact that it is not entirely clear whether private landowners in the Netherlands enjoyed the right to claim alluvion in terms of Roman-Dutch law, the South African courts have held that there is no doubt that private landowners do enjoy such a right in terms of South African common law and that such a right applies not only to the natural action of public rivers but also to the natural action of the sea.

Perhaps the most significant judgment in this respect is Van Niekerk.48 In this case the Appellate Division accepted that the owner of land bounded by a public river (the riparian owner) is entitled to claim the right to alluvion. Although this case applies to rivers and not the sea, it is discussed in some detail for the sake of presenting a complete picture of the common law position. The manner in which the courts have approached the application of the right to the natural action of the sea is considered thereafter.

In arriving at its conclusion the Appellate Division in Van Niekerk held that the conflicting approaches adopted by the Roman-Dutch authors to alluvion related only to those public rivers that were classified as navigable and not to those that were classified as non-navigable.49 This is because, the Appellate Division held further, a careful examination of the Book of Feuds (the Libri Feudorum)50 shows that only navigable rivers were made a part of the regalia. The Sovereign, therefore, was entitled to claim the right to

alluvion only in respect of navigable rivers and not in respect of non-navigable rivers.51

Now in this case we are concerned not with a navigable river but with one which is not navigable, and whatever the law may be as regards the former, there is no justification for holding that the latter falls under the regalia, and that their beds, therefore cannot be, alienated.52

Insofar as non-navigable public rivers were concerned, the Appellate Division went on to hold, it seems, that the rules that applied in Roman law also applied in Roman-Dutch law, and in Roman law riparian owners were entitled to claim the right to alluvion because the ownership of the beds and banks of public rivers vested in them.53 This distinction was significant, the Appellate Division concluded, because the Vaal River is not navigable. This meant that the beds and banks of the Vaal belonged to the riparian owners and, consequently, that like the owners of non-navigable public rivers in the Netherlands, they were entitled to claim the right to alluvion.54

Apart from the Vaal River, the Appellate Division has held that neither the Orange River55 nor the Crocodile River is navigable.56 It appears, therefore, that there are no navigable rivers in South Africa and, consequently, it is very unlikely that the South African state will be able to claim a right to alluvion insofar as agri non limitati are concerned.57

Unfortunately it is not clear whether the distinction drawn by the Appellate Division between navigable and non-navigable public rivers in Van Niekerk's case holds up to scrutiny. In a number of subsequent judgments the Appellate Division has held that not only navigable public rivers but also non-navigable public rivers were considered to be a part of the regalia and thus the property of the Sovereign.

For example, in Butgereit v Transvaal Canoe Union Rabie ACJ held that while Roman-Dutch jurists such as Grotius and Voet dealt only with the legal status of navigable public rivers in their respective works, it appears that "over the course of time all public rivers, whether navigable or not, became part of the regalia."58

The same point was made by Kotze JA in Surveyor-General (Cape) v Estate De Villiers.59 After stating that navigable rivers were made part of the regalia, the learned judge went on to say that the list of regalia mentioned in the Libri Feudorum was not regarded as a complete one and that in time "all things, the use of which was common and public by the Roman law … came to be embraced in the number."60

Given that both navigable and non-navigable public rivers were considered to be a part of the regalia, it follows that the right to claim alluvion must have vested in the Sovereign, not only in respect of navigable rivers but also in respect of non-navigable rivers. The fact that the Vaal River was not navigable, therefore, was irrelevant. In terms of the Appellate Division's own reasoning, the ownership of the bed and the banks of the river must have vested in the State. The riparian owner, therefore, was not entitled to claim the right to alluvion.

Although the reasoning of the Appellate Division in Van Niekerk may be criticised, this does not mean that its finding, namely that private landowners are entitled to claim the right to alluvion in terms of South African common law, is incorrect. As Sonnekus and Neels have argued, when it comes to determining whether the owner of an ager non limitatus adjacent to a public river is entitled to claim alluvion, the distinction drawn between navigable and non-navigable public rivers is irrelevant from a South African perspective. This is because the Sovereign's right to claim alluvion in Roman-Dutch law (initially from navigable and later from non-navigable rivers) was derived from his feudal regalian rights and these feudal rights were not received into South African law.61

Apart from public rivers, the South African courts have held that the right to claim alluvion also applies to the natural action of the sea. The most significant judgment in this respect is Colonial Government v Town Council of Cape Town.62 In this case, the Town Council of Cape Town reclaimed land from the sea along the shore of Table Bay without obtaining the consent of the Colonial Government to do so. After the Town Council began constructing buildings on the reclaimed land, the Colonial Government applied for an order prohibiting it from doing so. In response, the Town Council argued inter alia that as the owner of the adjoining land above the high-water mark it had acquired ownership of the reclaimed land by accession in the form of alluvion.

De Villiers CJ rejected this argument on two grounds. First, there was no proof that the Town Council was the owner of the adjoining land63 and, second, the addition of the reclaimed land was not gradual or imperceptible and thus did not satisfy the requirements of alluvion.64 In his concurring judgment Maasdorp J went a step further and held that almost none of the requirements of alluvion had been satisfied. In particular, the addition of the reclaimed land had not been produced by the natural actions of the sea. Instead it had been artificially constructed by the Town Council.65

Two important points emerge from this judgment. First, the Court held by implication that the doctrine applies not only to land bounded by a non-navigable public river but also to land bounded by the sea. Although the Court did not refer to any authority in support of this finding, the same approach appears to have been followed in Roman-Dutch law. De Groot, for example, describes alluvion as a process that takes place "when the river or the sea [adds] something imperceptibly to the land, and what was so added [belongs] to the owners of the land where the alluvion occurred."66 Like De Groot, Huber also refers explicitly to the sea in his description of alluvion. Alluvion, he states, occurs "when a sea or river gradually causes anything to grow on to any person's land, which addition at once becomes the private property of the lord of the adjoining land."67

Second, the Court held that alluvion could not be advanced by artificial means but only by the natural action of the sea. Once again the Court did not refer to any authority in support of this finding, which is unfortunate. This

is because in Roman-Dutch law alluvion could be advanced by artificial means, provided navigation and the rights of neighbours were not impeded. De Groot, for example, states that "[p]ersons who have the right of alluvion may promote the said alluvion by laying dams, driving in stakes and other works, so far as the common fair-way, any person's fishery, or the lands opposite are not injured thereby."68

Apart from being natural, the increase in land must also be gradual. According to Voet this means that soil must be added so gradually that it is "impossible to perceive how much is added at any particular moment in time."69 In a similar vein Van Leeuwen also states that the increase of land must be so gradual "that it cannot be calculated how much is added in each moment of time."70

Although this requirement has not been addressed by the South African courts, it was considered by the Privy Council on several occasions. In Attorney-General of Southern Nigeria v John Holt and Co Ltd,71 for example, the Privy Council held that the words "slow and gradual" must be understood as referring only to the manner of the accretion and not to its result. The increase of land must therefore be "imperceptible in its progress, not imperceptible after a long lapse of time."72 In Secretary of State for India v Vizianagaram (Rajah),73 in turn, the Privy Council recognised that the test of gradualness is not based on a fixed standard but is a relative one which must be applied to actual conditions. This meant that "the actual rate of progress necessary to satisfy the rule when used in connection with English rivers is not necessarily the same when applied to rivers in India."74 Given that avulsive events must be excluded from alluvion, the English courts have also recognised that a "logical, and practical gap" or "grey area exists between what is imperceptible and what is considered avulsion" and so the issue of what may be described as imperceptible or otherwise is always a question of fact.75

In the light of these judgments South African scholars have argued that a landowner who wishes to claim a right to alluvion must fulfil the requirements set out below:

(a) the increase of land must have occurred because of the "natural and gradual and imperceptible deposit of soil;"

(b) the soil must have been deposited as a result of the action of a non-navigable public river or the action of the sea; and

(c) the land itself must be an ager non limitatus and bordered by a public river or the sea. In those cases in which the land is an ager limitatus rather than an ager non limitatus, any alluvion accrues to the state.76

6 National Environmental Management: Integrated Coastal Management Act77

6.1 Introduction

Having set out the common law rules governing the acquisition of ownership by means of alluvion, we may now turn to consider the changes that have been brought about by the NEM: ICMA. As its preamble states, the goal of this Act is inter alia to give effect to the environmental rights guaranteed in section 24 of the Constitution and in particular the right guaranteed in section 24(b) "to have the [coastal] environment conserved and protected for the benefit of present and future generations through reasonable legislative and other measures."

This broad goal is translated into more specific objects in section 2 of the NEM: ICMA. One of these is to "preserve, protect, extend and enhance the status of coastal public property as being held in trust by the State on behalf of all South Africans, including future generations."78 In order to achieve this object the Act introduces a new thing or res known as "coastal public property" and vests ownership of this new thing in the citizens of South

Africa.79 In addition, the Act provides that coastal public property will be held in trust by the State.80

Coastal public property encompasses the area where the land meets the sea and is made up of several different components. These components may be divided into three categories, namely those that relate to the landward side of coastal public property; those that relate to the seaward side of coastal public property; and those that relate to both the landward and seaward sides of coastal public property.

Insofar as the landward side is concerned, coastal public property is made up of the following components:

(a) the seashore, including the seashore of a natural or reclaimed island as well as the seashore of reclaimed land;81 and

(b) any admiralty reserve owned by the State,82 as well as any land that is owned or controlled by the State and is declared to be coastal public property.83

Insofar as the seaward side is concerned, coastal public property is made up of the following components:

(a) coastal waters,84 including land submerged or flooded by coastal waters as well as the substrata beneath such land;85 and

(b) any natural island within coastal waters.86

Insofar as both the landward and seaward sides are concerned, coastal public property is made up of any natural resource on or in any of the components set out above.87

One of the most significant components of the definition of coastal public property is the "seashore". This is because in most cases it will determine the landward boundary of coastal public property and most importantly the boundary between that part of the coast that may be privately owned and that part that may not be so owned.

The seashore is defined in section 1 of the NEM: ICMA as the "area between the low-water mark and the high-water mark". The low-water mark, in turn, is defined as "the lowest line to which coastal waters recede during spring tides", and the high-water mark as the "highest line reached by coastal waters, but excluding any line reached as a result of exceptional or abnormal weather or sea conditions, or an estuary being closed to the sea."88

An important consequence of these definitions is that the landward boundary of coastal public property is based primarily on the position of the high-water mark. In other words, the high-water mark forms the boundary between public and private property.

6.2 Changes in the high-water mark

Apart from making provision for coastal public property, the NEM: ICMA also deals with changes in the high-water mark. When the Act first came into operation it regulated changes in the high-water mark brought about because of both coastal erosion and coastal accretion. Changes brought about as a result of coastal erosion were regulated by section 14(5) of the Act, while changes brought about as a result of coastal accretion were regulated by section 14(6).

Insofar as coastal erosion was concerned, section 14(5) provided that:

If the high-water mark moves inland of the boundary line of a land unit due to the erosion of the coast, sea-level rise or other causes, and remains inland of that boundary line for a period of three years, the owner of that land unit:

(a) loses ownership of any portion of that land unit that is situated below the high-water mark; and

(b) is not entitled to compensation from the State for that loss of ownership, unless the movement of the high-water mark was caused by an intentional or negligent act or omission by an organ of state and was a reasonably foreseeable consequence of that act or omission.

And insofar as coastal accretion was concerned, section 14(6) stated that:

If accretion occurs, whether as a result of natural processes or human activities, land which formed part of the seashore when this Act took effect and which subsequently becomes situated inland of the high-water mark as a result of a change in the position of the high-water mark, remains coastal public property, and does not become part of any adjoining property unless the property is bounded by the high-water mark or extends to a staled distance from the high-water mark.

The reference in section 14(6) of the NEM: ICMA to property that is "bounded by the high-water mark" or which "extends to a stated distance from the high-water mark" appeared to be a reference to an argus non limitatus. In terms of the common law, however, it has always been possible for a part of the seashore to be incorporated into a unit of land as a result of alluvion. With one exception, therefore, section 14(6) simply seemed to codify the common law principles governing the acquisition of land by alluvion.

The exception related to the fact that section 14(6) referred to accretion that had occurred either as a result of natural processes or human activities. As we have already seen, in Colonial Government v Town Council of Cape Town the court held, contrary to the principles of Roman-Dutch law, that alluvion could not be advanced by artificial means but only by the natural actions of the sea. The reference to "human activities" in section 14(6), therefore, marked a return to the Roman-Dutch position, at least insofar as littoral owners were concerned.

In 2014 section 14(5) of the NEM: ICMA was amended in various respects and section 14(6) was repealed.89 Unfortunately it is not entirely clear why section 14(5) was amended and section 14(6) repealed. The Memorandum on the Objects of the Amendment Bill simply states that these amendments were aimed at clarifying "the consequences of the high-water mark moving inland or seaward".90 The amended section 14(5) now reads as follows:

If the highwater mark is landward of a straight line boundary of a coastal land unit when this Act took effect, or the highwater mark moves landward of a

straight line boundary of a coastal land unit due to the erosion of the coast, sea level rise or other causes, the owner of that coastal land unit:

(a) loses ownership of any portion of that coastal land unit that is situated below the highwater mark to the extent that such land unit becomes coastal public property; and

(b) is not entitled to compensation from the State for that loss of ownership, unless the movement of the highwater mark was caused by an intentional or negligent act or omission by an organ of state and was a reasonably foreseeable consequence of that act or omission.

The reference in section 14(5) of the NEM: ICMA to a "straight line boundary of a coastal land unit"91 appears to be a reference to a coastal land unit that is enclosed on all sides with artificial and not natural boundaries (i.e. to an ager limitatus). If this is correct, it follows that – at common law – the seaward boundary of such a coastal land unit cannot move landward because of the landward movement of the high-water mark. This is because the common law provides that the seaward boundary is fixed and not ambulatory.

An important consequence of this common law principle is that if the high-water mark does move landward of the straight line boundary of such a coastal land unit "due to the erosion of the coast, sea level rise or other causes", the portion of land situated between the straight line boundary and the high-water mark (the inundated portion) will retain its status as private property despite the fact that it has been inundated by seawater and may no longer be accessible or of any use to the landowner.

A plain reading of section 14(5)(a) of the NEM: ICMA, however, shows that it has effectively abolished this common law rule. This is because it expressly provides that if the high-water mark was already inland of the straight-line boundary of a coastal land unit when the Act came into operation or moves inland of such a boundary after the Act came into operation the inundated portion becomes a part of the seashore and thus coastal public property. As such it can no longer be privately owned.

In the light of these points it is submitted that the purpose behind section 14(5)(a) of the NEM: ICMA is to replace the existing fixed straight line boundary of a coastal land unit with a new ambulatory high-water mark curvilinear boundary in two specific circumstances. Or, to put it another way, it is submitted that the purpose behind section 14(5)(a) of the Act is to bring the common law principles governing agri limitati in line with the common law principles governing agri non limitati in certain limited circumstances.

These specific circumstances are, first, where the high-water mark moved inland of the seaward boundary of the ager limitatus before the NEM: ICMA came into operation; and second, where the high-water mark moves inland of the seaward boundary line of an ager limitatus after the NEM: ICMA came into operation. Insofar as the second circumstance is concerned, the high-water mark must have moved inland of the straight-line boundary as a result of "the erosion of the coast, sea level rise or other causes".

As Sowman and Rebelo point out, these provisions have important consequences for the parcels of land to which they apply. One of the most important is that those parcels that were agri limitati will be re-classified as agri non limitati. This reclassification, they point out further, will be permanent because section 14(1) of the NEM: ICMA expressly provides that an ambulatory high-water mark curvilinear boundary, including one created in terms of section 14(5)(a), may not be replaced by a fixed straight-line boundary.92

Apart from pointing out the consequences of the provisions of section 14(5)(a) of the NEM: ICMA, Sowman and Rebelo also argue that these provisions appear to be aimed at phasing out the existence of agri limitati that are located adjacent to the seashore.93 Besides creating a uniform legal regime when it comes to the seaward boundaries of coastal land units, this goal will also promote an ecosystems-based approach towards conserving and protecting the coastal environment and will thus promote the aims and objects of the Act itself.

An ecosystems-based approach is one that seeks to manage an ecosystem on a holistic and integrated basis rather than a fragmented and sectoral one. This is because it recognises that ecosystems are a "rich mix of elements" that are connected to and interact with one another. One of the most important aspects of an ecosystems-based management approach, therefore, is that it is "fundamentally a place-based approach where an ecosystem represents the place." It thus favours natural boundaries such as the high-water mark over artificial ones such as a surveyed line.94

Despite its potential to make a positive contribution to the conservation and protection of the coastal environment, the provisions of section 14(5)(a) of the NEM: ICMA may nevertheless give rise to some complex and difficult problems. One of these is whether the owner of a coastal land unit that has been reclassified in terms of section 14(5)(a) as an agri non limitati is entitled to claim alluvion should the newly established ambulatory high-water mark

curvilinear boundary reverse course and retreat seawards past that coastal land unit's original fixed straight-line boundary as a result of a fall in the level of the sea.

Fischer and Whittal have made some helpful suggestions in this respect. One of these is that as soon as the ambulatory high-water mark retreats past the fixed straight-line boundary on its journey seaward, that fixed straight line boundary revives and consequently the landowner is not entitled to claim ownership of the newly created dry land area between the fixed straight line boundary and the now lower-lying ambulatory high-water mark. In other words, the landowner cannot claim ownership of this area by alluvion. As they note, this approach mirrors the common law rules governing the acquisition of ownership by alluvion in respect of agri limitati.95

Another suggestion is that when the ambulatory high-water mark retreats past the fixed straight-line boundary on its journey seaward, that fixed straight-line boundary is not revived. Instead, the ambulatory high-water mark curvilinear boundary continues to apply and consequently the landowner is entitled to claim ownership of the newly created dry land area between the fixed straight-line boundary and the now lower-lying ambulatory high-water mark. In other words, the landowner can claim ownership of this area by alluvion. As they note, this approach mirrors the common law rules governing the acquisition of ownership by alluvion in respect of agri non limitati.96

Although Fischer and Whittal are critical of the second approach and appear to favour the first, it is submitted that the second approach is correct for the reasons given by Sowman and Rebelo, namely that the effect of section 14(5)(a) of the NEM: ICMA is to substitute the straight line boundary of a coastal argus limitatus with a high-water mark curvilinear and ambulatory boundary; that in the light of section 14(1) this substitution is permanent; and consequently that the goal of section 14(5)(a) is to phase out the existence of agri limitati that are located adjacent to the sea shore.

Besides the reasons given by Sowman and Rebelo, the second approach also appears to be consistent with the manner in which Parliament understands the effect of section 14(5)(a) of the NEM: ICMA. This is because section 14(5)(b) expressly provides that, subject to certain exceptions,97 the owner of a coastal land unit is not entitled to claim

compensation as the result of the reclassification of his or her property as an ager non limitatus and the loss of ownership that will arise if the high-water mark moves landward. Without engaging in a full section 25(1) constitutional analysis,98 it submitted that this provision can be justified on the ground that the potential loss of ownership that a reclassified coastal land unit may now suffer as a result of the landward movement of the high-water mark is offset by the potential gain in ownership that may now be enjoyed as a result of the seaward movement of the high-water mark and the right to claim alluvion. This potential gain in ownership applies only to the second approach suggested by Fischer and Whittal and not the first.

7 Conclusion

Although the common law principles and rules governing the acquisition of ownership by alluvion have stood the test of time, it is important to note that they were developed in an age when the earth enjoyed a more stable climate. As the earth continues to get warmer, the climate will become less and less stable and this will inevitably call into question the efficacy and suitability of at least some of the legal concepts, principles and rules that regulate the ownership of land and other natural resources. Those concepts, principles or rules that do not facilitate climate change adaptation and mitigation may suffer the same fate as coastal land units that are agri limitati. In this respect, section 14(5) of the NEM: ICMA may be seen as a portent of reforms to come.

Finally, it remains for me to acknowledge the enormous contribution that Willemien du Plessis has made to the development of legal scholarship in South Africa over the course of her academic career, and to express my personal appreciation for the friendliness, kindness and generosity she has always shown towards me. She has set an example that we would do well to follow.

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List of Abbreviations