The creation of ‘hydro-maps’ is a method whereby people’s relationship to water is investigated via the interfaces between their developments, and the hydrology of the landscapes they inhabit. These maps correlate and collate a variety of water infrastructure types, urban patterns, and land-forms. They are therefore a tool for investigation, and while they are often created to test an assumption they have also provided new insights. For the case of the Sana’a Basin hydro-maps are used to analyse how the sustainability of pre-modern Sana’a was achieved. In contrast to the sustainable systems of pre-modern Sana’a, other hydro-maps depict modern development trends and hydro-interfaces that identify the basin’s incohesive and fragmented urban forms. The maps of pre-modern and modern Sana’a are compared for context, and to identify water management related incompatibilities.

The Sana’a Basin is located in the north-west of Yemen in between Mt. Nuqum and Mt. Ayban mountains in the Sarawat mountain range. Yemen owes its reputation as being dubbed Arabia Felix (Latin for fertile, happy and blessed Arabia) to this mountain range as its landscapes are characterised by several highland basins (refer figure 1) which are rich in alluvial soils and sub-soil aquifers. A basin-wide geographical analysis of pre-modern development locations, water paths and alluvial silts reveal the fractal-like nature of the landscapes in the Sana’a Basin and a resulting aggregated pattern of development (refer figure 3). The recursive fractal pattern of ephemeral rivers is comparable to a tree, whereby smaller tributaries from the mountains are like stems feeding into larger ones until they all eventually converge at the thick trunk - the Wadi al Sailah. This main ‘vessel’ of the catchment is where the basin’s largest settlement is located - the city of Sana’a. Higher amounts of floodwater and the abundance of alluvial soil predestined Sana’a’s predominance as a major city over the surrounding villages. This reasoned genesis and destiny of Sana’a is one example of how patterned spatial and societal generalities for the entire region could be identified, thereby providing a logical framework towards investigating specific case studies. Conversely, the discussed specifics of societies, vernacular developments, civic infrastructure, state infrastructure, cultural places of significance, and agricultural lands are correlated to exhibit broad patterns and generalities. While being factual as possible to address the topic with substantial information, the reductionist nature of such analyses is that the unique components of each and every aggregate cannot be proven as contributing to a broader system. Similarly, nor can each and every aggregate be proven as part of an apparent system assumed by the generalist ‘logical framework’ formulated. Considering the Sana’a-city-scale, Elsheshtawy acknowledges the balance of uniqueness and sameness found throughout the region in his description of the urban fabric and the architecture of the city’s towerhouses:

“The urban pattern of the city comprises many housing clusters that are similar in the orientation and spatial organization of their elements, but different in shape and size. It follows a hierarchical system of organization that seemed to be very efficient in providing appropriate functional spaces for both public and private zones and the required separation between them.”⁶

These and other recognised generalities form an understanding of pre-modern Sana’a, and provide a framework for such analysis. While these patterns themselves are worthy of analysis, it is the fracturing of these urban patterns which may signify a disjointed approach to water management. These disjointed patterns are generally seen in modern Sana’a, which does not conform to, or successfully integrate with a pre-modern pattern, nor has modern Sana’a formed its own cohesive urban pattern.

Figure 3: The multiplicity of villages in the Sana’a Basin indicate the city’s genesis ⁷ - 10 000m grid

Map Description:
For an area of approximately 36 000 hectares, the Sana’a Basin contains a relatively small variety of landforms which form in patterns across the region to create an equally and somewhat evenly dispersed set of landscapes. Mountainous terrain girt the region closely to the east and west, and, distantly to the south. Water run-off from these sandstone and volcanic mountains carry silt down the wadis (ephemeral rivers) which appear radially from the centre of the basin, forming a large floodplain. While Abuel-Lohom and Gad accurately depict the catchment leading water from the entire basin to a single natural outlet in the north,⁸ it appears water rarely leaves the basin as the alluvial floodplain (and therefore the flood water which carries its silt) stops over 10 kilometres short of the northern low point.⁹ This is probably due to the massiveness of the floodplain, where the run-off water is usually absorbed into a large underground aquifer on which Sana’a is founded.¹⁰ The weak alluvial soils are easily dug into wells and provide much of the arable soil in the region. These patterned geographies are therefore the generators of the patterned placement of settlements throughout the basin.

p>The arid climate of Sana’a receives a petty average of 265mm of rainfall per year, though up to 60mm of this may fall in 24 hours. Additionally, annual rainfall is focused in two short wet seasons whereby approximately two thirds of the average rainfall occurs in the three months of April, July and August. It is common for the region to experience very little rainfall for five months over Summer.¹⁴

In order to accommodate these extreme contrasts of flood and drought, the region, just like many other regions in the world, had traditionally devised and evolved practices which capacitate flood water, effectively mitigating floods and drought. Responses to the landscapes’ and the climate’s flooding and drought are evident in the agricultural practices, development patterns and even societal hierarchies of the region. For the vast majority, if not all pre-modern developments in the Sana’a Basin, the ancient urban practices of agriculture on a wadi bed with overlooking flood-resilient towerhouses in between define the basic urban character of the region. Investigations at a finer scale reveal a definitive collection of small scale infrastructures; spate distributing canal systems, dykes, terraces, cisterns, canals from mosques’ ablution baths, wells, and public baths, all of which are functionally arranged/adjacent to intelligently use and re-use what little water falls on the region, examples of these are described and depicted throughout this thesis. Terraces are a notable example of small-scale infrastructures multiplied extensively to mitigate floods and use water very efficiently, their action will be explained further in case study 1. The increased groundwater permeation from the practice of constructing agricultural terraces found on the foothills surrounding the lower basin not only irrigate the crops and recharge the groundwater aquifer but also prevent excess runoff which would otherwise contribute to flooding downstream in the city.¹⁵

A feedback loop occurs whereby these small-scale infrastructure systems which contribute to a regional system of water management are both generated from and yet premise components of the region’s traditional political hierarchy. Specifically in the case described by the Food and Agriculture Organization, authorities and their parent hierarchies are appointed and organised (respectively) to manage irrigation disputes and the community’s water supply (refer figure 8):

“In Hadran (in the Directorate of Bani Matar, Sana’a Governorate), Yemen, the grand sheikh (sheikh daman) represents the whole community within official circles, deals with tribal and rangeland disputes at the sub-district level (uz-lah), and is responsible for solving problems at the village level. The rank of the sheikh at the local (uzlat) level comes after that of the grand sheikh. The “wise man” (akel), is found at the third level, tackles land and irrigation disputes, and collects the religious tax (zakat) from the farmers…. The sheiks are responsible for supervising the rangeland activities related to hema, and the mukaddam (guardian, usually the head of an extended family) of the mian (water source), who is selected by farmers, is responsible for distributing irrigation water, and cleaning and maintenance of the irrigation system.”¹⁶

This governance hierarchy resultantly effected the physical outcomes of these system’s parent infrastructures, architectures and urban fabrics. These relationships between human needs, social hierarchies and the landscape were in turn influenced by living environments. This is one example of the aforementioned feedback loops whereby society, development and landscape are all interrelated.

Over time, the ongoing influence from these feedback loops created a series of systems with countless dependents (refer figure 9 series). Primarily, this interdependent system of infrastructural patterns, human-networks, customs, laws and manicured hydro-landscapes were the product of the people’s needs to seek shelter, mitigate flood, access water and produce food. In effect, changing landscapes, people, and their development practices were influentially interwoven and/or tangled around human needs (water, food and shelter) as they changed through time. The existence of this composite system is found, in some form at least in all traditional, modern and traditional-modern-hybrid societies, though they each exercise varying levels of success in managing flood, food and water.

Notably, there are also pre-modern examples of large scale infrastructure projects which exhibit a more ambitious and centralised approach to water access and flood mitigation. Even as far back as the 8th century BC, when the region was governed by the ancient Sabeans a massive dam was built 100kms to the east. The Ma’rib Dam was a complex feat of engineering for the time with an earthen bank 600m long, a series of several sluices to control its outlets and overflows, and a distribution tank with many outlets to feed the city of Ma’rib.¹⁷ Without this dam which flourished the Sabean empire, Sana’a may not have ever of been founded. The construction of Sana’a’s enormous mud fortification in the 9th century has completely diverted the flood-course of Mt. Nuqum which once ran through the city. Parts of this wall key to mitigating this flood remain after 1200 years (compare figures 9.2 and 9.4).¹⁸ There are also pre-modern occurrences where the urban society and the state collaborated on large-scale manifestations of small-scale systems, for example Sulayhid Queen Awra of the 11th century had spent much of the throne’s annual budget on repairing terraces.¹⁹

Figure 6: 1946 map of the Old City by the British Navy²⁰

Figure 7: Topical locations of the Old City, Bir al-Zab and in between²¹

The locations pinned in this map have been referenced throughout the thesis.

Figure 8: Comparison of pre-modern and modern political structures/hierarchies²²

2.2 Tracking the premises of the 1962 revolution

The aforementioned hierarchical structures of the traditional government system appear soft by today’s standards, in that they delegated powers to the regional tribal authorities so that these leaders could manage themselves and the small scale societal and infrastructural networks as quoted earlier. However, the Imam Yahya Hamid Ed-Din, who was the second last King of the 688-year monarchy of Yemen (excluding the interluding years when the Turks ruled on two occasions), like the Imams before him conserved himself and his system via strident restrictions of, international transport, communication, trade/reform, and the media throughout most of the first half of the 20th century.³² Citizens were effectively isolated from the evolving world as explained in the opening sentences of Burrowes’ paper The Famous Forty and Their Companions:

“To a remarkable degree, Imam Yahya Hamid al-Din of Yemen insulated the traditional Islamic country he ruled from the modern world for a generation – in part, by not allowing his subjects to leave his domain.”³³

Al-Abdin further explains the psychology behind the dictator in the following words:

“The colonization of Arab countries by Britain and France and of Abyssinia by Italy was a lesson fresh in Yahya’s mind. Thus, he jealously guarded the sovereignty of his country and its traditional religious way of life by isolating it from foreign influence. He refused to allow in the country diplomatic missions or Western commercial companies or to encourage any form of contact with the outside world. He answered a critic, who pointed out the economic benefits that foreign firms would bring to the country, by saying that they did not help India to avert repeated famines; and that he and his people would rather eat straw than allow foreigners into the Yemen.”³⁴

In the 1940’s the Free Yemeni Movement rose against the monarchy that conserved the aforementioned systems in a rapidly developing world. The people of Yemen learned from the movement’s members who shared their acquired knowledge of the technologies and societies of the outside world, where modern governments and trade reform improved human rights and living conditions.³⁵ Notably, Imam Yahya Hamid ed-Din himself had sent out forty men to several foreign countries throughout the middle-east and even Europe to learn new skills of governance for his restless population, though these men upon their return would actually work towards breaking down the country’s segregation from the global community, contributing to the end of the conservative monarchy.³⁶ A civil war broke out in 1962 against the Imam al-Badr who took the throne that year after Imam ed-Din died in his sleep.³⁷ Militarily supported by the Egyptians whom were well invested in the ideology of Pan-arabism,³⁸ Yemeni rebels would fight the monarchy for eight years of civil war before becoming relatively stable (politically speaking) republic in north Yemen (refer figure 5 for chronology).

Figure 10: Imam Badr was contested since taking the throne in 1962 and was overthrown in 1970 ⁴⁰

Figure 11: Abdullah Al-Salal, leader in the 1962 revolution and first president of Yemen Arab Republic³⁹

Figure 12: Royalists marching along a wadi bed in 1962⁴¹

The historical iterations of the masterplan for Sana’a, namely the Egyptian Plans of around 1968 (refer to figure 13) and the Berger/Kampsax 1978 masterplan (refer to figure 14) anticipated the expansion of a new Sana’a as a sole objective, whereby site context such as agricultural functions and village relationships were barely considered but for their assimilation into a new civic system. In ignoring the existing context, ie the fabric of the villages and their cultural and geographical premises, these plans also rejected the historical knowledge of the landscape developed through the patterned nature of its long-evolved settlements. The masterplanners being from outside the region, and outside the continent for that matter probably contributed to this disregard of geographical context.⁵⁶ This modern overhaul arguably has caused a negative change within the lifestyles of the Yemen people, whereby their traditional practices are hybridised by the pervasive modernity and globalisation of Sana’a. Though there are beneficial factors within these hybrid lifestyles of old and new, including the modern expectations of high living standards and better human rights, making it difficult to isolate modern overhauls as being ill-considered and superfluous aside from those born out of necessity. In this case study the masterplans for Sana’a are reasoned and yet proven as generators for the incohesive urban fabric and rampant centralisation of the region.

Vernanda’s doctoral thesis focused on the masterplanning of Sana’a is summarised here, with particular emphasis on the authorisers and long-term outcomes of such a plan. Prior to a recognised masterplan, the Ministry of Public Works had, upon the inception of the ministry in 1968, used a set of documents called the Egyptian Plans which in essence overlay a grid around the existing fabric of Sana’a and two other large towns in the region (refer to figure 13). In 1970, a physical planning division of the Ministry of Public Works became operational with the arrival of a United Nations Development Programme expert Alain Bertaud’ who was brought to Sana’a to establish the city’s first recognised masterplan, which was begun in 1971 to be fully implemented in 1978. This plan estimated the population of 1988 to be 280 000, about half of what would be the actual population in that year. Because of this gross underestimation, the city sprawled in an unpredictable way which the masterplanners predicted would be the case if no planning policies and planning infrastructures had been enacted. In 1980 experts from the German Volunteer Service were employed by the Ministry of Municipalities and Housing to decentralise the nation and bring regional townships to a modern standard,⁵⁷ even this proved ineffective for the already overgrown city; Sana’a’s population exploded in this decade.

As described by Elsheshtawy previously quoted in this thesis, the absence of an adequate framework for development in the masterplans for Sana’a has created a disjointed urban fabric. This is further exacerbated by the ongoing use of the helplessly outdated masterplan of 1978, which failed to predict the immense and domineering population growth within the city.⁵⁸ The placement of main roads determined by the 1978 masterplan radially emerged from the planned city’s centre just west of the Old City and just east of the historic Bir-al’Zab which once stood within the western ‘wing’ of the city’s walls. Despite this pattern’s intent to potentially decentralise the dense inner city,⁵⁹ it inadvertently encouraged rural-urban migration from the outlying villages it connected to as well as facilitated the unplanned development of an in between zone, as evident in figure 15. The organisation of government buildings seem to follow similar disregard, adjacencies between ministries and other government organisations are inefficiently scattered,⁶⁰ which perhaps contributed to, or partially resulted from the lack of cross-sectorial approaches (including the water sector) within the government which further exacerbated water mismanagement.⁶¹ These inefficiencies and inabilities were and still remain characteristics of an incompetent government wielding an incomplete and outdated plan, and so what had once been a rather successful decentralised pattern of development in Yemen has now been compromised by unguided modernisation and centralisation. In the case of the Old City, its functioning and traditional past-times were drowned by the confused modern city which effectively smothered it:

"(the Old City) has been flattered out and forced to express conditions of habitat and functioning leveled on those of the other city districts. The new urban form has been scattered to fragmented land use and to heterogeneous gated communities rather than homogenous communities within the old walled city gates."⁶²

Eckert explains this kind of bipolar phenomena by making an example of a peculiar interaction between traditional relationships people have of the city’s marketplace while explaining the intricacies of these habits as changing due to inadvertent modernisation:

"The esplanade of bab al-Yaman outside the city walls, simultaneously an ‘urban port’ for the central souks, a working class central district and the city’s largest public transport terminus, appears as a huge central monopoly untempered by any outside pole of attraction, reflecting the rapidly growing city. Coaches, buses and taxis pour in from a wide area with no anchorage point. They come from gates that are constantly moving further out into the country and that have no concrete existence apart from the vegetable stalls that appear here and there on the pavements of the outer districts…
… We are forced to admit that everything that happens at Bab al-Yaman and in the souks, and that the large volume of vehicles and pedestrians is the most important quantitative and qualitative expression of this. The reason is that the city seems to be at the mercy of land speculation that both encourages and prevents the urbanization of specific areas and aims as much at housing as at rows of shops, which leads to movements outwards… They (Yemenis) only seem to feel comfortable doing their shopping and other business in the familiar universe of the souks (in the old city), and the prestigious urban souks at that."⁶³

This is one example of how the historical city’s systemic functioning has been compromised, the souks (markets) of the Old City which retain their significance in a modern city do not maintain the sustainability of their traditional histories. The failed masterplan as allowing a problematic modern-traditional complex to occur is one example whereby efforts to accommodate for a larger population, provide modern services (namely water supply, sewerage, stormwater and sealed roads) for better living conditions, better accessibility, undertake heritage conservation and simply provide for oneself and one’s family, all have rippling effects away from the direction of their intended action. These inadvertent effects are channelled from one society’s hydro-interface with the Wadi al Sailah to another, and to another again. The snowballing of these uncoordinated effects of the disjointed societies within this city has contributed to its evermore failing management of flood, food and water. This phenomenon will be explored in the next three case studies.

Figure 13: ~1968 Egyptian Plans⁶⁴

Figure 14: 1978 Masterplan by Berger / Kampsax⁶⁵

Figure 15: The growing development of modern Sana'a in the Sana'a Basin ⁶⁶ - 5 000 grid

The shifting and contradicting recommendations of UNESCO for the conservation of the Wadi al Sailah is an example on how one of many organisations had attempted to rein the negative effects of population growth on the Old City’s traditional functioning. The differences between two advisory texts from 1986 and 1992 are of dramatic contrast — one before the population boom had truly began and one after have seemingly contradictory recommendations

Yemeni people have traditionally used wadis for roads as they lead to villages and contain the most accessible groundwater and are therefore spotted with an abundance of wells.⁷⁰ However, people would have traditionally entered through the city’s main gates; Bab al’Yaman to the south and Bab Sha’ub to the north, not its Khandadiq (floodgates) which are along the wadi bed. With the introduction of the car which cannot traverse the tight-knit streets of the Old City, the Wadi al Sailah became a central component of access to the internal souks of the historic urban fabric,⁷¹ though Ali Abdul Moghri Street (which bordered the since removed wall of the Old City) would and still does most prominent thoroughfare (refer figure 7 and 16). Still, because of the ongoing densification in between the Old City and Bir-al’Zab, characterised by several impermeable public squares and government complexes, the Wadi al Sailah has eventually become yet another thoroughfare. Discussion on infrastructural interventions to improve the Wadi al Sailah had been conferred by designers and policy makers since the 1970s, though modern interventions began only in 1987 - the modest conservation endeavour to restore mud walls and banks which protect the Old City from monsoons.⁷² Its 1994 urban transformation into a paved and depressed four lane highway73 was warned against by renown urban conservationist architect Ronald Lewcock just 8 years before in 1986:

“A particular danger that has to be avoided is the cutting through of a main road across the “Old City” from north to south; this has already been proposed above a covered-over sa’ilah (dry riverbed) where the flood waters run. Its effect would be catastrophic, irrevocably dividing the traditional way of life of the people of the “Old City” into two weaker, fragmented zones, and inevitably attracting high commercial buildings on either side of it. From the viewpoint of conservation it would introduce alien features of such a scale and impact that the conservation of the western half of the “Old City” - and therefore ultimately of the whole - would become meaningless.”⁷⁴

In an interesting contradiction to Lewcock’s recommendation, six years later, Eckert (another conservationist of heritage environments who works with UNESCO) describes the prospect of roadway-canalisation within the Old City as a “reality that needs to be brought under control”⁷⁵ listing the benefits of such an intervention:

...Reinforcing its fragile banks would make it possible to reconcile the natural function of draining occasional rain and flood waters with the specific function of “draining off” vehicles entering the road system within the walls, in such a way as to also preserve the supplementary functions of Wadi Saila; A ‘rampart’ just behind Bab as-Sabah, a car access via the Harat al-Qasimi ramp, landscaping: an urban riverside and a mirror image of the Medina all along the bank.⁷⁶

Arguably, the difference between Lewcock’s and Eckert’s recommendations perhaps lie in the distinction between the road’s prospective functions of protected and maintained access to the Old City versus that of the road as becoming thoroughfare. While UNESCO was involved in developing traffic plans for the Wadi al Sailah (despite them only being implemented in 2004),⁷⁷ neither Lewcock nor Eckert made such considerations or technical distinctions in the texts cited. Also contradictory to Lewcock’s concerns of the city being divided, Eckert later claims that the connection from east to the west by the proposed introduction of several footbridges (which would eventually be built regardless) would do harm to the surrounding areas:

“(it would) threaten the tranquility of one of the finest residential sectors of Old Sana’a. The quiet and privacy of this attractive district, apparent in its gardens and small squares, would suffer greatly from this (pedestrian traffic).”⁷⁸

Essentially, both scholars had concerns regarding interruptions to the ancient urban fabric and the traditional societal networks of the areas around the Wadi al Sailah. In 1986 Lewcock predicted the formalising of Wadi al Sailah into a major paved road would have divided the traditional relationships between people either side of the wadi, while in 1992, Eckert claimed that due to the intense civic commute from the region into the Old City constructing a road would have at least taken pressure off the city’s gates (namely Bal al’Yaman) and aided the functioning of the adjacent souks. Eckert went on to claim that connecting each riparian edge of the wadi with footbridges, a solution which at face value seems to facilitate the urban relationships Lewcock claimed would be otherwise lost due to the wadi’s canalisation, would have in fact destroyed the urban fabric of the surrounding areas. Eckert’s reasoning was that due to the densification of the new city centre between Bir-al’Zab and the Old City, the wadi-canal-road without footbridges was acting as a buffer from those who would otherwise trek through the Old City’s neighbourhoods to the central souks.⁷⁹ The shifting approaches towards conservation by UNESCO advisors owe their contradictions to a small window of time, characterised by an unfathomable rate of change in population growth (see figure 5 and 17). The changing opinions of professionals in the field of conservation not only iterate the complexities of a rapidly changing Sana’a but also the difficulties of exercising solutions in a region where societies are both communicatively and cooperatively severed from one another and yet influentially connected.

The canalisation of the Wadi al Sailah into a four-lane thoroughfare and the construction of five additional footbridges over it were both undertaken in 1994 despite Lewcock’s and Eckert’s recommendations.⁸⁰ Both scholars were also correct in their concerns that such infrastructures would cause negative effects on the Old City. Michele Lakrambos describes the residents’ distaste in cookie-cutter modernist/globalist typologies being constructed on the Old City’s new popularised esplanade:

“Residents of the “Old City” and others protested against construction of the theatre-arguing that the use of waqf property for entertainment went against the original intention of the patron (waqif). Moreover, the garden was attached to a mosque: entertainment and music were not appropriate for this site. The controversy was covered in the press, and provoked a debate in Parliament. On my rounds with inspectors, we were approached by a young man who demanded to know why GOPHCY (General Organisation for the Preservation of Historic Cities of Yemen) was not discussing the matter. Any modernization (istihdath) on the “Old City” of Sana’a is forbidden,” he said. “It says so on the Internet” (i.e., on UNESCO’s website). According to a GOPHCY official, residents found UNESCO’s proposal of a public garden more appealing, and more compatible with the waqif’s intentions. In their effort to preserve these intentions-and, implicitly, to resist the coopting of their city by an elite and alien program-residents invoked the authority of UNESCO alongside Islamic Law. During the months of Ramadan that year, in what may have been an effort to appease residents, the theatre was used for performances of religious music *tawshih) by groups of from different parts of Yemen.”⁸¹

The civic access of a main arterial road coupled with the globalist gentrification of its esplanade has placed an untraditional and unprecedented importance on the adjacent districts, eroding their urban performance and heritage values. In a specific case modern infrastructures have begun to transform the towerhouses on the eastern esplanade, these modern infrastructures are; footbridge connections leading to the relatively new city centre, the growing area of carparks (which presumably service the central souks as described by Eckert) and the latter being facilitated by the adjacent vehicle ramps to the Wadi al Sailah. A meaningful correlation can be made between; aerial photography from 2004-2016, maps which define the towerhouses’ ground-floor programs and a map depicting the occurrence of recent renovations and refurbishments of these towerhouses. With this data it can be recognised that there is a trend in refurbishments and renovations to accommodate retail and service programs which cloister new carparks.⁸² Additionally, the creation of impermeable surfaces through canalisation and carparks has reduced the groundwater permeation (refer figure 21), further contributing to the reduction of the groundwater aquifer and the unviability of traditional agricultural practices of the vernacular urban environment, this phenomenon will be described in detail in the following case study.

Figure 16: Road use map⁸³

Figure 17: Timeline of conservation of and around the Wadi al Sailah⁸⁴ - click photo to enlarge

Figures 18 and 19: Section across and elevation along the Wadi al Sailah^{85 86}

Legend:
a. Sloped canal wall (~40 degree inclination). The gentle stone paved sections of the Wadi al Sailah are designed to be traversable.
b. Road into Old City
c. Esplanade planter
d. Towerhouse
e. Esplanade storefront
f. Inaccessible towerhouse. Due to the tiered urbanity throughout the city and the risk of flood from the Wadi al Sailah, many towerhouses do not address the esplanade. The higher internal floor leads means the esplanade is edged with a stone wall in this case.
g. Carpark. There are many carparks around the Wadi al Sailah road/canal as the Old City is barely traversable by car.
h. Terraced esplanade.
i. Many courtyards partly compose the esplanade to the Wadi al Sailah. They feature ornate stone details and maintained display gardens.
j. Wadi al Sailah road is approximately 10m wide throughout the Old City. This is a tight 4 lane highway. The profile of the road means it can function when carrying small amounts of stormwater.
k. Bus stop on the edge of the sloped canal wall.
l. Brick course work about 300mm high designed in a pattern to allow water to permeate through. Terraced threshold up to storefront are often ~ 400mm high.
n. During times of little rainfall, the profile of the road forms large gutters at its edge.
o. The typical flood of the Wadi al Sailah forbids its use as a road.
p. Diagrammatic representation of 2008 floods where floodwater covered the esplanade and rose up the high thresholds of the nearby buildings.
q. The flood of 878 / 879 AD flooded The Great Mosque. As this was after the fortification was constructed diverting the Mount Nuqum flood course it is assumed that this flood came from the Wadi al Sailah. The level depicted is about 1.5 metres above the floor of The Great Mosque several hundred metres upstream and 15 metres higher in elevation. This flood event may be nothing more than a legend.

Figure 20: Water and flood systems/conditions of the Old City⁸⁷

Note: This map is based off the area around Maqashama Al-Kharaaz and Al-Jala’a however some building typologies and wadi-city interfaces have been introduced to complete the catalogue. Considerable accuracy in the representation of urbanities, water related typologies and their spatial relationships has been retained.

Figure 21: Water table height, depths of wells and their distance from the Wadi al Sailah throughout time - 20m grid ⁸⁸

Figure description:

This section diagram depicts the falling groundwater levels around the Wadi al Sailah. Evidently, after the canalisation of the wadi in 1994 and the massive population increase since the late 1980s the groundwater table has dropped considerably. In both post-canalisation dates 2002 and 2007, the three wells closest to the wadi appear most affected. The lines representing the well depths continue past the groundwater table indicating their changing depths throughout time.

Map Description:

The pressure built from the city’s limits (mountains, airport and wastewater treatment facility) result in the inward compression against the most flood prone lands of the Wadi al Sailah floodplain. In the centre of the modern city (segment 5), the threshold between development and the wadi has been reduced to a retaining wall and a street, interfaced by tall structures which look over the wadi, several kilometres north, the city begins to open up to agricultural programs which interject between the wadi and modern development, this reduced pressure to develop thankfully leaves the traditional fabric of the historic settlement Al-Rawdah largely intact. Evident in segments 1 and 2 is the airport and the wastewater trench. Here, dense informal developments disperse into small albeit growing clusters girt by large expansive farmland. Unlike the pressurised modern city, the farms along the wadi bed to the north promote groundwater permeation instead of flushing water downstream.

Informal developments emerge as proof of polarisation between an arrested, insufficient state and a resistant, resilient traditional population. More specifically, the genesis of informal developments and their ongoing development is the product of the clash between the traditional lifestyles of the people and the arrested state which fails to control its assets or provide an adequate framework for development. The effect is very significant with approximately 16.5 - 20.5% of Sana’a’s population residing in informal developments.⁹⁷ Hema Al’ Matar, the third largest of the informal developments in Sana’a which houses 27 000 people (as of 2008), is located at the northern mouth of the canal on Wadi al Sailah as the plume of development visible in figure 22. Development further north in segments 1 and 2 (figure 22) do not appear formal either, though they aren’t recognised as Hema Al’ Matar by Shorbagi.⁹⁸ Emerging around 1990, Hema Al’ Matar has manipulated the Wadi al Sailah bed with an organic arrangement of housing and extensive farmland.⁹⁹ This development and other informal developments in the region haven’t earned their legitimacy, the state not only intervenes with infrastructural interventions but also seeks to relocate these people. While concerns of the inhabitants living conditions and safety are legitimate, other agendas of corrupt state officials have also been documented.¹⁰⁰

Despite its intentions, the state is generally inefficient at providing alternatives or even haltering the ongoing illegal sale of land in these informal developments. Shorbagi describes how an arrested and inefficient state facilitates farmers’ illegitimate claims to land which can then be sold illegally to those looking to build a home:

“The state has no exact inventory of its own land which facilitates encroachment by private persons, particularly on the slopes adjacent to agricultural land 20% of which can be legally claimed by private land owners to protect their water resources. However, private land owners often occupy much larger land parcels and tend to claim non-agricultural land as agricultural land to support their claims of ownership. In practice, it is the State that has to prove ownership in case of first registrations without knowing the exact boundaries of public land which opens the door for all sorts of manipulations. Therefore, land is in most cases traded informally with the use of written documents (basa’ir) that are certified by the amin al-mantiqa, a government appointed area chief.”¹⁰¹

Obviously these developments would not have been planned in the 1978 masterplan, and in most cases are illegal encroachments on prohibited land. In the case of Hema Al’ Matar, this development prohibition is based on a few reasons, foremost being the state’s security and safety concerns regarding the nearby airport. While claimed to be not as important of a problem to the state, part of this land along the Wadi al Sailah is also zoned as “saila” which the government claims are floodplains unfit for development.¹⁰² The nearby sewage plant is another reason for the lack of official development in this area prior to 1990 when the settlement first emerged.¹⁰³ The Food and Agriculture Organisation stresses that the agricultural use of the wastewater trench which trails approximately thirty kilometres from the partially-functioning treatment plant along the Wadi al Sailah is a "serious health concern".¹⁰⁴ Despite this, water from the wastewater trench as well as natural floodwater is used for farming the surrounding wadi bed, just the area would have been like in pre-modern times.

Modern interventions seeking to rightfully improve poor living conditions in informal developments cause inadvertent problems in the urban fabric of these quasi-vernacular developments. Reported in interviews with residents of a different informal development, Mahwar Aser, the construction of schools, road paving, sewers, health centres and other vital infrastructure has been funded by the World Bank.¹⁰⁵ While Hema ‘Al Matar has not been as significantly canalised (deepened or paved) in comparison to the Old City and the modern city, the introduction of bitumen roads either side of the Wadi al Sailah rise above a depressed floodway for a length of 1,200 metres within the informal development.¹⁰⁶ This work was presumably undertaken by the state and perhaps funded by the World Bank as was the case in other informal developments. The rigid structure of these sealed roads protect the wadi banks from erosion, and therefore protect the poorly built masonry buildings on these banks.¹⁰⁷ However this canalisation also compromises the surrounding wadi bed’s use as an agricultural plain by concentrating floodwater to a singular canal, denying the spilling of floodwater to the broader floodplain and spate-canals, as well as simply reducing the amount of land which can be farmed in the wadi bed. Roads on the riparian edge provide access to floodplains of now defunct agricultural land, and so they are sold off for development. Also evident as in the other areas of the city already discussed, the phenomenon of the wadi becoming a road promotes development precariously close to the floodplain.¹⁰⁸

This analysis of the complex relationships between state infrastructure and informal developments reveals the many interwoven chains of influence and their varied mediums. In the case of Hemar Al’ Matar, the construction of a road influences land titles which in turn influence informal development patterns; these informal development patterns also draw other civic influences such as the economy of the airport, and canalisation of the wadi which leads to extensive development on a floodplain (refer to figure 23 and 24). Rather than these people being integrated into a broader holistic system or harmoniously integrating modernist interventions into their hydro-interface/urban fabric, they are internally conflicted and externally ill-considered, if at all, negatively affecting the livelihoods of the inhabitants while propelling their population growth.

Figure 23: Farming plots as generators for patterns of informal development¹⁰⁹

Map description:
In Hema Al Matar, the farms’ relationship with the Wadi al Sailah is also a premise for its ongoing pattern of development (not just its genesis). Land tenure is a key influencer of informal development as evident in the analysis of pre-existing farming plots and the developments which are built on them between 2004 and 2016. The aggregated clustering of buildings and their joined cloistering forms in the informal developments in and around Sana’a are reminiscent of the pre-modern vernacular settlements of the region, insinuating a similar geographical and social premise to pre-modern villages.

Figure 24: Patterns of informal development¹¹⁰

Map callouts:
a. Figurative path of the Wadi al Sailah prior to the construction of the city’s wastewater treatment plant as evident by the river’s path to the north and south of this infrastructure. b. Development encroaching on the wadi is also seen just to the south of this point while development which relies on an upstream premise can be seen in the developments on the far north of the figure.
c. Canalisation goes back 1,200 metres from this point.
d. Recent development of an area which would experience considerable velocity flood water coming from around the bend. Its development is encouraged by the canal/road infrastructure.
e. Houses removed from wadi due to slip-road canalisation.

Map description:

It has been demonstrated that as people settle large plots of agricultural land with the aims of wadi access and road access, properties are divided in thin bands between and perpendicular to the wadi and the road. This confines informal development to a similar pattern when particular land-owners informally subdivide their land. This causes the ongoing growth of informal developments to eventually interface and interrupt the wadi, changing its course and the surrounding landscape profoundly.¹¹¹ Additionally, Shorbagi states that prospective residents of informal developments avoid authorities during the construction of these developments, by initially screening views from the road with development, growth behind and towards the wadi is less visible and perhaps less likely to draw attention.¹¹²

As the development reaches out onto the wadi, flood waters are slowed downstream, causing sediment to settle which further directs the path of the wadi away from these areas which are then developed. This pattern repeats spatially throughout the informal development, compounding over the years studied.