INTRODUCTION
Anambra is one of the most flood devastated states in Nigeria. This research aims to understand the cause of flooding and the impact it has on Anambra state. It bulds on traditional building typologies and responses to the environmental conditions to identify contextual strategies that are historically informed. It explores the environment and its resources for local materials that can be used to develop innovative and sustainable flood mitigative building strategies.
During this research supported by Heinrich Böll Foundation Abuja Office, representatives of Anambra state government reported about their challenges in securing adequate funding for flood mitigation projects in their yearly budgets. This stresses a need for interventions that are cost efficient and a need for locally sourced and produced solutions. These solutions must engage with local craftsmen by utilising skills already available, fostering economic growth and building capacity. In terms of legacy, it is important to preserve traditional architecture and perpetuate local building methods indigenous to areas which are at risk of the annihilation of historical and architectural monuments.
We thank the Managing Director of Anambra State Physical Planning Board, Barrister Chike Maduekwe and the Chairman of Anambra Urban Regeneration Council, Arc. Michael Okwonkwo for their relentless support in making this research possible. We equally appreciate the efforts of Ms. Ugochi Ehiahuruike from SIDEC, who, thanks to her wide network in Anambra state, made sure to connect us to affected communities and local professionals whose knowledge and contributions were instrumental in developing various architectural typologies proposed at the end of this booklet. We also appreciate the support and
This booklet describes the first phase of the research, exploring indigenous flood risk mitigation strategies to encourage innovative, contextual solutions in and around the floodways. Research and consultations will continue to ultimately encourage ecological restoration and environmental preservation as part of local government infrastructure plans and to reinforce a network between the vulnerable communities, local professionals and local and state government bodies in order to create a feedback loop between problems and solutions.
Aim
» To explore indigenous flood risk mitigation strategies and encourage innovative, contextual solutions in and around the floodways.
» To encourage ecological restoration and environmental preservation as part of local government infrastructure.
» To reinforce a network between the vulnerable communities, local professionals and local government bodies in order to create a feedback loop between problems and solutions.
Objectives
» Identify historical and traditional conditions of living in floodplains and floodways.
» Identify indigenous resources, traditional construction methods and building materials that can be integrated in urban flood mitigation strategies - field work in coordination with the local communities.
» Propose innovative, contextual architectural applications and urban flood mitigation interventions - with local and regional professionals. discussions with the Department of Environmental Sciences of the Nnamdi Azikiwe University, Akwa.
Anambra is the most densely populated state located in the south-eastern region of Nigeria. It is bounded by Delta state to the west, Imo state and Rivers state to the south, Enugu state to the east and Kogi state to the north. Anambra is positioned about 184km from the Niger Benue confluence. Originally, Anambra was part of the Nri kingdom, one of the oldest settlements in Nigeria. Currently, it is made up of 127 communities divided into 22 Local Government Areas. The state capital is Awka, while the state’s largest city is Onitsha.
HISTORY & ECONOMY
Anambra was part of the Nri kingdom, making it one of the oldest settlements in Nigeria, in the Igbo-dominated area with the Igbo language serving as a lingua franca throughout the state. Anambra state was created in 1976 and Enugu served as its capital forming part of East Central State. On August 27 1991, Anambra was divided into two, Enugu which was the capital of Anambra was made into a state with this act the capital was moved from Enugu to Awka.
Major economic activities of Anambra include agriculture, manufacturing and commerce. The agricultural activities include farming, livestock and forestry in the rural community. The current economic powerhouse of Anambra lies in its industrial areas at Onitsha and Nnewi. Onitsha market is described as the largest in West Africa and has strong trade links with many parts of Nigeria and other countries pre and post colonization. Nnewi is fast becoming the automobile spare parts market for the nation and the industrial area is growing rapidly.
Anambra is divided up into these local governments areas:
• Anambra East
• Anambra West
• Ayamelum
• Ogbaru
• Onitsha North
• Onitsha South
• Oyi
• Orumba South
• Nnewi North
• Awka North
• Awka South
• Anaocha
• Dunukofia
• Idemili North
• Idemili South
• Njikoka
• Aguata
• Ekwusigo
The state is richly endowed with mineral deposits such as kaolin and clay, coal, ironstone, sandstone, and bentonite, still leaving a lot of solid minerals untapped. Anambra drainage sediments are used for construction; thus, sediment mining is a constant practice. Sediment mining increases erosion risks within the basin via uncoordinated widening and deepening of river channels.
RELIGION
Traditional religion dominated this region before the acceptance of Christianity during and post colonization. Today, both Christianity and traditional religions co-exist as the major religions.
Ala, the earth goddess, is an omni-present witness to all the actions of people living on its earth. It provides the mud with which the building is shaped. The superiority of the land goddess over all other deities in traditional Igbo depicts the importance of land.
When Christianity was brought by the Europeans, who taught the Igbo that God lived in heaven, the superiority bestowed upon Ala was transferred to Igwe, hence, the saying, “Igwe ka Ala ” (the sky which is superior to the earth).
CLIMATE
Anambra has two distinct seasons: Rainy (southwestern monsoon winds from the Atlantic Ocean) and Harmattan (north-eastern dry winds from across the Sahara desert).
The rainy season spans through April and July, followed by a two to three weeks dry period in August with the rain resuming in September and October. Harmattan also known as ‘Ugulu’ in Igbo occurs between November to March.
Aambra has a tropical wet and dry or savann climate with yearly temperature of 28.99°C (84.18°F). The temperature is generally 27–30 °C between June and December but rises to 32–34 °C between January and April.
WATER BODIES
The main drainage system for the state is the Anambra River which empties into River Niger. A network of rivers and streams in the area form an extensive drainage pattern that covers most of the state. The major rivers include the southwardflowing Niger River, which flows into the Atlantic Ocean, and the Anambra River, which flows southward into the Niger River. The cuesta is drained by other rivers including the Nkisi, Idemili, Uchu, Aghomili, Mamu, and Crashi Rivers. The Agulu, Uchu, and Ulasi Lakes are some of the lakes that also drain the area.
TOPOGRAPHY & ELEVATION
Anambra has two ridges, or cuestas, that lie in a north–south direction. These ridges form the major topographical features of the area. The topographic features of the area distinctly influence erosion potential. The ridges have long steep slopes that enhance surface water runoff velocity which gather momentum to produce force that easily and quickly detaches and transports soil particles, which results in gullies.
The low to near flat land is below 60m above sea level and is found in Ayamelum, Anambra West, Awka North, Onitsha North, Onitsha South and Ogbaru. The elevation above the flatlands is between 60-120m above and is found in Anambra East, Idemili South, Oyi, Dunukofia, Awka South, Nnewi North and Nnewi South Local Government Areas. This is followed by elevations of between 120-230m, the highlands, which are found in Anaocha, Aguata, Orumba North, Orumba South and Awka South Local Government Areas. The highest grounds lie from 230-385 -m and are found in Idemili South, Aguata, and Orumba South.
SOIL & GULLY EROSION
Four soil texture types were identified in Anambra state: coarse textured, fine textured, medium/fine textured and medium textured. The soil erodibility ranged between 0.20 and 0.28. Areas with low values indicate low capacities to withstand soil erosion while areas with high values indicate high capacities to withstand soil erosion. In other words, areas that are highly vulnerable to soil erosion are the areas contributing more to average soil loss in the state and vice versa.
Anambra has been nicknamed the 'Gully Erosion Capital' due to a vast amount of gully erosion cases that plague the region. Gully erosion is the removal of soil along drainage lines by surface water runoff. Gully erosion happens when runoff concentrates and flows strongly enough to detach and move soil particles. The combination of heavy rainfall and loose unconsolidated soil results in gully erosion along the vast drainage network that encompasses the region.
LOWLAND FLOODING
The people of the lowlands have given names to the major flood occurrences to mark them as a monument in time and a notable force of nature
1970 flood - Ijuogu. Occurred during the ending of the Nigeria/Biafra war. The flood was said to be the first flood disaster that got the people of Ogbaru asking if the world was about to come to an end.
1998 flood - Okeiju. It was another flooding record that Ogbaru had as they tagged it Okeiju (heavy flood) because water covered everywhere to the extent that people started killing wild animals being chased by the flood.
2012 flood - Oso Iju. That flood shut down both the economic and socio economic activities in the local government. The people suffered the menace of the flood for 3 years.
2022 flood: Unnamed. The most recent and highest so far and most devastating.
LOWLANDS
The lowlands consist of farming and fishing communities due to the close proximity to the Niger River. The communities generally produced yams, rice, and fish. The Niger River, or “Plenitude of Waters” as Onitsha people call it, have long served as places for stable human settlement in sharp contrast to the floodplains, which historically have posed much greater obstacles to longterm occupation because of the massive seasonal flooding. Ogbaru residents recount the yearly flooding of the Niger River as long as their history can recount. Today, these communities are the most affected by the climate change impacts of increased flood levels.
UPLANDS
The uplands are the regions that lie 60-300+ meters above sea level. Historically, these lands were used to farm large scale palm oil. Onitsha, however, is the tip of the uplands that borders the Niger River, therefore making it a major commercial hub. Onitsha has always had an interesting relationship with the Nigeria River, being a port city and a major trade hub for the country. Its high elevation have saved it from the floods that yearly innundate the lowlands. This allowed it to develop into the dense urban cluster that it is today.
THE 2012 AND 2022 FLOODS
The 2012 flood was the most disastrous flooding in Nigeria, and it devastated Anambra. With 10,000 homes fully or partially submerged, and 20,000 structures affected, it cost $185 million in economic damages. The 2022 were also severe,affecting 74% of rural households and 40% of urban households; it cost an estimated $9.1 bn in economic damages.
Overall, 64% of households were affected by the 2022 floods, with impacts ranging from livelihood, housing, food sources and access to basic services, such as health facilities and schools.
IF FLOODING HAS ALWAYS OCCURED IN THE LOWLANDS, WHY WAS THE 2012 AND 2022 FLOOD SO DISASTEROUS?
2012 FLOOD
13 local government areas affected 117,148 farms and agro-based industry damaged
10,000 homes fully or partially submerged
20,000 structures affected $185 million in economic damages
2022 FLOOD
FLUVIAL FLOOD
Fluvial flooding occurs when rivers and streams break their banks and water flows out onto the adjacent lowlying areas (the natural floodplains). In the 2012 and 2022 flood occurrence, the release of water from the Lagdo Dam caused a fluvial flood in Anambra. The places most susceptible to annual flooding were hit the hardest, namely Anambra West and Ogbaru. These farm lands were completely devastated and most houses were completely submerged.
DEFORESTATION
But if flooding has been occurring in these regions, why was it so devastating this time?
Pre Colonial settlers have been farming this region since before the first major flood occurrence. The difference is not the activity and settlement of this area, but change in the performance of the landscape. A map from 1896 displays a forested region that borders the Niger River outlined in red. The dense forests are circled in red, one being located right above Anambra. This forested barrier around the river protects and stabilizes it. The trees protect the bands from erosion, increase the amount of water the river can store, and act as a defense wall for the floodplain.
These factors are a relief for the regions downstream because water can be stored in the trees and the velocity of the river decreases as it passes through the resilient bends. Without this protective barrier, the floodplain is highly susceptible to aggressive flooding and erosion.
The Google Earth capture shows the difference in the Niger River in 1986 and in 2020. The protective forest barrier has been largely deforested, thus leaving the river exposed and vulnerable. This deforestation leaves the ground cover exposed, thus increasing the siltation rate of the river. It also increases flooding and passes the
devastation downstream from state to state.
Anambra has experienced a change in landscape performance especially in the lowlands. What was once farmland buttressed with forests are now farmlands left defenseless. Today only 7% of Anambra has tree cover. The trees removed from these regions protected the lowlands from intense flooding. For example the neem tree restores and maintains soil fertility and the african plum reduces soil erosion and landslides. These trees are essential to a landscape that is composed of loose unconsolidated soil. The lowlands have developed into vast, extensive farmlands, leaving the ground exposed and susceptible to disastrous flooding.
Farming isn’t bad for rivers, many cities farm on the river; however farming without forest protection is disastrous. Without this cover, the river fluctuates greatly and the inhabitants in this region suffer greatly during the
raining season. A rural area with a forested barrier is more stable and the inhabitants here are protected by this vegetation. This is an optimized floodplain. It allows the river to change its form, stores water, regulates flow velocity, and allows the inhabitants to benefit from the fertile soil without hindering its functions.
PLUVIAN FLOODING
The causes of pluvial flooding are listed in the image shown at the top of page 13. Highlighted are the causes that are linked to anthropogenic actions. Most of these causes are man made, which means that they are man solvable. When thinking about flooding in Anambra, the images that come to mind are clogged drainages in poor neighborhoods, houses built on waterways, and large forests being deforested to make way for housing developments. However, these flood causes can be found in the most common house. For example, most of the surface of a plot is impermeable. Also the drainage often leads to the ground, which leads to a single drainage point, the gutter. This is not optimal because it overwhelms the gutters, causing flooding.
Architecture must find ways of providing multiple outlets for drainage in the same way that nature does. Provisions should be made for runoff from the roof and the ground to find its way back into the earth at an appropriate flow rate. The runoff is currently only making its way into the gutter, and these gutters are pushing all the runoff from every
plot down towards the floodplain and into the river. The accumulation of the runoff overwhelms the floodplain and this in addition to the flooding of the river creates a disastrous outcome for the inhabitants of the lowlands.
We need to interrogate every single aspect of the way we build and ask ourselves, is this optimal?
WHAT IS A FLOOD PLAIN?
A floodplain is the first line of defense for the city, all activities and structures here should aim to optimize the performance of the river. Optimizing the floodplain means optimizing the performance of the river. The current urban development on the floodplain is suboptimal. The floodplain is meant to protect the water quality, recharge the groundwater, preserve the ecosystem, and prevent obstructions from the river. The river essentially acts as an artery that supplies the floodplain and vice versa; everything happening on the floodplain affects the performance of this artery. Because the floodplain is connected to the
rest of the land, this also translates upwards to the highlands.
The landscape can be divided in zones 1-3 to understand the flow of causality. Everything happening in the uplands also affects the performance of the floodplain, which in the end affects the performance of the river. If the performance of the environment in zone 3 is poor, the performance of zone 1 will also be poor. The floodplain becomes overwhelmed, the amount of rainfall exceeds the capacity of urban storm water drainage systems or the ground to absorb it. This excess water flows overland, and devastates lowlying areas.
FLOOD PLAIN FUNCTIONALITY
A key understanding from pluvial flooding is that the performance of the river doesn’t start at the lowlands but rather at the uplands. The diagrams below show how water is meant to move through the environment. Typically, water is supposed to infiltrate the ground while some of the water runs off the surface. Some of the water is retained by trees which reduces the amount of water flowing into the drainage channels. This water is stored until it is ready to be released through evapotranspiration. Some of the water is meant
to percolate into the baseflow and recharge the groundwater. Some of this baseflow water makes its way to the river through an underground flow.
Currently our cities are built like the diagram shown in the bottom instead. Hard, impermeable surfaces force the water to runoff the surface and quickly move downwards into the river, overwhelming the drainage, eroding the landscape, silting the river, and causing flooding. Rather than a division of drainage options, and a diversity of waterflow, all of the water is channeled towards the river at the same time, causing pluvial flooding.
How
Rather than a diversity of waterflow, all of the water is channeled towards the river at the same time, causing
A NEW APPROACH TO OLD PROBLEMS
In Beijing, a similar problem to Anambra was occuring. The city was constantly plagued with the task of solving urban flooding. Kongjian Yu, a landscape architect, proposed the idea of a sponge city, enabling the city to absorb large amounts of water. In Singapore, a similar approach is taking place. They have aggressively stated their intentions to be the greenest city in the world and to have 80% of their surface cover be vegetation, optimizing the built environment's functionality. In Bali, rather than adding vegetation to the buildings, Stilt Studio is lifting the buildings above the ground in order to allow the environment to function naturally. These solutions can also be found at the material scale. Researchers in Australia and Copenhagen have developed permeable concrete that is able to allow water to permeate the earth.
Beijing and Singapore both drew from traditional methods of step farming. This indigenous practice that strategically increases the total surface area of a landscape was used to develop a contemporary solution that maximizes the water uptake of entire cities. Stilt studio investigates the spiritual aspects of Balinese architecture that creates hierarchical spaces based on different levels of dwelling. India’s ancient stepwells were known for their ingenious ways of harvesting rainwater in large pools that could provide for entire communities. Permeable concrete was modeled to perform like natural porous structures such as bone marrow and coral, which are naturally light and water permeable structures. These projects all vary greatly because they are designed with indigenous knowledge that was built within their environment.
HYDROPHILIA
Kongjian Yu Beijing, China
STILT STUDIO
Stilt Studio Bali, Indonesia
HYDRO HOUSE Biome Bangalore, India
Standaert
INDIGENOUS KNOWLEDGE
The definition of Indigenous Knowledge is the sum total and wide array of skills and knowledge accumulated over generations by people in a specific geographical/regional area which enables them to manage and co-exist in their natural environment.
The knowledge systems have evolved from many years of experience and trial and error problem solving by groups of people working to meet the challenges they face in their local environments, drawing upon the resources they have at hand (Olokesusi, 2006;Wahab, 2010)
The global scientific community acknowledged the relevance of indigenous knowledge and endorsed it at the World Conference on Science held in Budapest, Hungary, from 29 June to 1 July in 1999 by recommending that scientific and traditional knowledge should be integrated particularly in the field of environment and development (UNESCO, 2000).
The knowledge systems have evolved from many years of experience and trial and error problem solving by groups of people working to meet the challenges they face in their local environments, drawing upon the resources they have at hand (Olokesusi, 2006;Wahab, 2010)
The global scientific community acknowledged the relevance of indigenous knowledge and endorsed it at the World Conference on Science held in Budapest, Hungary, from 29 June to 1 July in 1999 by recommending that scientific and traditional knowledge should be integrated particularly in the field of environment and development (UNESCO, 2000).
INDIGENOUS KNOWLEDGE IN NIGERIAN ARCHITECTURE
Northern:
Walls of great thickness and height for ventilation
Material: habe-hausa clay ball construction for thick walls
Edo and Tiv:
Profiled facades to keep large parts of them in the shade while increasing radiation of heat accumulated for night time warmth
Material: red clay construction for thick walls
Igbo:
Insulated houses with thick grass thatch, with open courtyards to receive rain water
Material: wattle and daub construction with sandy soils
• Communal settlements, massive compound gates, meeting houses (Obu), shrines (OkwuAlusi), rooms (mkpachi/ime ulo), and two storey semi-defensive buildings (Obuna Enu/Ulo Enu)Land is also very prominent in igbo cosmology as one of the alusi (deities) which guide the world. It therefore has had a remarkable influence on Igbo socio-political evolution in the past, and remains the most important asset the Igbo have.
• Traditional building finishes, such as mud plastering, intricate wood carvings e.t.c were highly valued due to their availability, affordability, and cultural significance.
• Pitch roofing was the common pattern of roofing traditional Igbo buildings
POST COLONIAL ARCHITECTURE
Although it might seem like the Igbo community copied and imbibed western culture, the impact of the western culture on Igbo architecture was not total. Most of the changes in Igbo architecture can be attributed to change in societal practices. The issue of building too many houses in one compound was phased out due to Igbos adapting a monogamous lifestyle. This changed the layout of the traditional compound. Some of the traditional practices, however, were retained, for example, a compound still has a single entrance and exit.
There are two architectural languages that currently exist in Igboland. One style is the traditional Igbo architectural design which has remained unchanged, while the other is a blend of western architecture and traditional Igbo designs. The first style was carried by the local people while the latter served the interest and needs of the groups of higher economic income and social status.
One major development in building walls during the post colonial era was the use of blocks.; however, this did not eradicate the use of puddled clay for forming the walls of buildings. Some people, particularly people in the very low income group still make use of this traditional building techniques while those that have defered to the western architecture influence make use of sandcrete blocks. Most of the so-called modern buildings cannot stand the test of time, due to the inconsistent construction. The houses were built using the same technique as the mud houses; metal rods were hardly used at the lintel levels or for laying strong foundations. Meanwhile, the core traditional Igbo buildings have lasted for over forty years.
The impact of the western influences on the general culture of the Igbo is reflected in the roofing designs of post-colonial Igbo houses. Rectangular building plans and pitch roofing plans have remained as the architectural zeitgeist. The most common designs in post-colonial times were the German roofing designs, gable roofing designs, and conical roofing designs.
The wider choice of modern building materials is
one of the more obvious influences of modernity on Igbo vernacular architecture. Buildings are more compact with rooms opening into one another with a single common roof over them. The compound is no longer in the centre but around the building. Pitched roofs have been maintained on contemporary buildings due to the frequent rains; however modern roofing materials are now used.
External wall facades made up of carved images and murals are now absent from contemporary Igbo architecture. Rather, modern paints and wall tiles are applied. Where community members used to join hands to raise buildings, now paid labor is the common method of building. Modernity has brought about a disintegration of community and extended family lifestyle.
PRE COLONIAL ARCHITECTURE
The pre colonial architecture of Anambra state is characterized by the Igbo traditional architecture which was deeply rooted in the culture, environment, and available local resources. Common architectural features are rectangular plans of dwellings which are without windows, the veranda in front of the houses and the use of forked posts to carry the roofs. Town planning features are communal settlement, massive compound gates, meeting houses (Obu), shrines (Okwu-Alusi), rooms (mkpachi/ime ulo), and two storey semi-defensive buildings (Obuna Enu/Ulo Enu).
Every compound is fenced with only one entrance and exit. The men’s section is separated from the women, and the children section is grouped together. Mud and thatch were the majour materials for the construction of a building, the roof are usually high Pitch which is a common pattern of roofing in traditional Igbo buildings.
Traditional building finishes, such as mud plastering, intricate wood carvings e.t.c were highly valued due to their availability, affordability, and cultural significance. Buildings were reinforced with bamboo strips on high foundation of 600-1200mm with a canoe hung by the door entrance for ease of mobility during flooding.
The people living in the riverine areas had to build to cope with constant flooding. Land erosion also frequently occured in the escarpment zone in the Awka-Orla uplands, at the east of the NsukkaOkigwi escarpment and around the villages of Agulu, Nanka and Oko.
Land is very prominent in igbo cosmology as one of the alusi (deities) which guide the world and all activities in it. This had a remarkable influence on igbo socio-political evolution in the past, and remains the most important asset the igbo have.
ANAMBRA ARCHITECTURE
The pre-colonial architecture of Anambra state is characterized by the Igbo traditional architecture which was deeply rooted in the culture. Looking at the traditional Anambra architecture, it is visible that problems were solved through a direct understanding of the environment. An understanding of vegetation properties, such as palm's hydrophobic wax, enabled people to construct thatch roofs that easily repelled water. While an understanding of wind flow and the soil's capabilities allowed them to form their malleable houses around ventilated courtyards. Today, these environmental understandings can be seen in scientific subjects such as horticulture and geomorphology.
Indigenous knowledge used many tools to understand and overcome their environmental challenges through collective observations, some of which include:
• Behaviour of local flora
• Meteorological knowledge for flood predictions
• Lunar observations
• Behaviour of aquatic animals and birds
• Observing the colour of water bodies
• Monitoring sounds from rivers and torrents
• Studying the mobilization of ants
• Scarcity of certain vegetations
Today we are faced again with new environmental problems and we cannot keep using solutions that were not built for our environment. The difference between our built environment today and that of pre colonial Anambra is that pre colonial Anambra Architecture was surrounded by a vibrant and diverse environment. Today Anambra inhabitants are enclosed in isolated houses surrounded by pavement and lacking environmental diversity to learn from.
A key question arises.
How do we bridge the gap between our built environment and our natural environment, optimizing not only urban development but individual development?
FLOOD MITIGATIVE TYPOLOGIES
Developing flood mitigative architecture built on indigenous knowledge.
TYPOLOGIES
Using various parameters of indigenous knowledge and contexts, the following three tables for mitigative architectural design were created to make use of local building materials and respond to local climatic conditions. They offer different ways of managing rainwater and surface water runoff. Each table considers three different income levels (low, middle, high) in order to create feasible options for every group as well as the building's location in proximity to the river (zone 1, 2, 3).
METHODOLOGY
A survey was conducted after the research in order to present the findings as well as work with a focus group on developing flood risk mitigative architectural proposals that draw from indigenous knowledge. Typologies were designed and presented to the participants of the survey.
The presented typologies were in three categories: solutions to retrofit existing houses, solutions for new buildings, and solutions for urban infrastructure. The typologies were presented in a matrix with one axis being the zone in which the proposals were located and the other axis being the income level for the proposed design.
Table 1 (page 26-27) presents designs for retrofitting existing buildings to make the more flood resilient (in zone 1 retrofitting was not judged feasible).
Table 2 (page 28-29) presents designs for newly built residential houses.
Table 3 (page 30-31) presents designs for public spaces differentiating the income level of people living around these public spaces.
Some areas in zone 2 are prone to flooding due to its closeness to the floodplains, The inten�on is to protect the buildings from the nega�ve effect of flood and to also reduce the speed of water runoff by increasing the permeability into the soil and crea�ng diversions and longer routes to reduce the speed of water run offs.
Zone 3 consists mainly of the uplands and has loose and unconsolidated soil prone to gully erosion. The goal is to reduce water permeability by using ground cover materials that also prevents the washing away of the top soil.
The level of flood in the floodplains- zone 1 has been on the rise over the years, the goal is therefore to discourage people from living on the floodplains and rather protect the exis�ng structures from the nega�ve impact of the flood and crea�ng public buildings to serve as safety structures during flooding.
Some areas in zone 2 are prone to flooding due to its closeness to the flood
plains, The inten�on is to protect the buildings from the nega�ve effect of flood and to also reduce the speed of water runoff by increasing the permeability into the soil and crea�ng diversions and longer routes to reduce the speed of water run offs.
Zone 3 consists mainly of the uplands and has loose and unconsolidated soil prone to gully erosion. The goal is to reduce water permeability by using ground cover materials that also prevents the washing away of the top soil.
Direc�on
3
The level of flood in the floodplains- zone 1 has been on the rise over the years, the goal is therefore to discourage people from living on the floodplains and rather protect the exis�ng structures from the nega�ve impact of the flood and create public buildings to serve as safety structures during flooding.
Due to the slopy nature in the Zone 2 which increases water runoff speed down to the flood plains, the goal is to increase permeability of water into the ground and to reduce water runoff speed through the use of grass, gravel, roof that slows down water run off, swales and by crea�ng a gradient landscape
Zone 3 consists mainly of the uplands and has loose and unconsolidated soil prone to gully erosion. The goal is to reduce permeability through the use of water collec�on and by using ground cover materials that allows water runoff while also preven�ng the washing away of the top soil. The building is also raised on low s�lt to avoid digging a large surface of the soil for founda�on.
IMAGE REFERENCE
1. The Nri Kingdom Map. Source: [www. amightytree.org]
2. Onitsha Map. Source: [www.amightytree.org]
3. Onitsha lowlands and highlands map. Source: [www.amightytree.org]
4. Onitsha market. Source: [www.amightytree. org]
5. Otu, Onitsha Waterside 1960s. Source [www. amightytree.org]
6. African Catholicism: The Birth of the Liturgical Vernacular in Igboland. Source: [https://churchlifejournal.nd.edu/ assets/318955/1200x/capture2.png]
7. The painted wall of a shrine in Nimo, Anambra State. Source: [ukpuru.tumblr.com]
8. A visit with the Obas of Lagos in the Obi. Source [https://amightytree.org/power-andritual-paradox-in-onitsha/]
9. Anambra contour map. Source: E. Ahuchaogu Udo1, O. C. Ojinnaka2, A. C. Chukwuocha1, U. Duru Uchenna (2021). Terrain Modeling and Analysis Using Earth Observation System Based Data: A Case Study of Anambra State, Nigeria. Open Access Library Journal.
10. A glimpse of the highlands. Robert McWhirter records 1905-11. Source: [amightytree.org]
11. Niger Delta region relief map.
12. Oba axis of Onitsha-Owerri expressway. Source: [https://theroundtable.com.ng/ thumb/211912718920.jpg]
13. Anambra Governor Inspects Gully Erosion Site In Nkisi-Aroli. Source: [https://www.youtube. com/@ChannelsTelevision]
14. Onitsha map 1932. Source: [amightytree.org]
15. The geographical grounding of cultural contrast. Source: [www.amightytree.org]
16. Onitsha marketside early 60s. Source: [www. amightytree.org]
17. Nsugbe vista. Source: [www.amightytree.org]
18. Asaba landing close. Source: [amightytree. org]
19. Deadly Flood Hit Many Nigerian States || Communities Submerged By Flood In Anambra. Source: [https://www.youtube. com/@outravelandtour]
20. Anambra flood victims cry for help. Source: [https://www.thetidenewsonline.com/]
21. Ossomala Farmers Fault Distribution Of Flood Relief Funds. Source: [Channelstv.com]
22. Flooding in Ogbaru
23. Map of Hausaland, Scottish Geographical Society (SGS), 1896. Souce: [https://www. caboose.org.uk/b/archives/2007/06/20/oldmaps-of-nigeria/]
24. Types of floods. Source: [Fluvial, Pluvial, and Coastal Floods - Zulkarnain Hassan]
25. A bridge somewhere in Igbo country. Source: https://ukpuru.tumblr.com/ post/183223292302/
26. House building in Onitsha, c. 1930. Source: [https://ukpuru.tumblr.com/ post/159343231842/]
27. A Street scene in Kano. Soure: TuckDB Postcards
28. Edo architecture. Source: Architecture of Nigeria by Kevin Carroll
29. Ekpe (leopard society) meeting house. Source: [https://jonesarchive.siu.edu/]
30. Part of colonial residential quarters in Enugu. Source: Ikebude, Chukwuemeka M.. “Identity in Igbo Architecture: Ekwuru, Obi, and the African Continental Bank Building.” (2009).
31. An ekweruru at Umuatuegwu, Okija. Source: Ikebude, Chukwuemeka M.. “Identity in Igbo Architecture: Ekwuru, Obi, and the African Continental Bank Building.” (2009).
32. Okechukwu, the Ogene's home in EnuOnicha. Source: [https://amightytree.org/enuonicha-inland-town-1960-62/]
33. Motor license office, Anambra. Source: [https://www.nairaland.com/5952378/checkout-ancient-building-used]
34. Nurses’ “Bungalow” Onitsha. Built by R McWhirter 1908. Source: [amightytree.org]
35. NGWO (AWKA [IGBO]). Composite pillars supporting the eaves. Zbigniew Dmochowski, 1960s. Source: [https://ukpuru.tumblr.com/ post/28721902586/]
36. 25 May 1905. Ibiaku-Ikot-Udum [Akwa Ibom, Nigeria]. [Ibibio] Woman’s spirit house. Charles S. Partridge. Source: https://ukpuru.tumblr. com/post/30099697158/
37. Traditional Igbo house 1967. Source: Wikimedia Commons - Drs. G.W. (Gerrit Willem) Grootenhuis (1930)
38. The Ezi compound. Source: [Ottenberg S., 1968: Double Descent in an African Society; the Afikpo Village-Group. University of Washington Press].
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