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Dam-Bridge in Tanaff Valley

Balouo Salo Location: Tanaff Valley, Region de Sedhiou, Senegal, Africa
Start project: 2015
Our supports: Engineering design, construction management, education, building materials
Engineering design: R. Vecchio
Consultations: A.Ghersi, S. D'Urso, C.Modica, D. Distefano, S. Cirami, Ruwa srl, M. Souane
Status: Ministries management
Donors: Privates, companies and publics, UCEI, Kaira Looro
International collaborations: Catania University, Tokyo University
Senegalese collaborations: senegaleses ministeries, Sedhiou Gouvernement, Chambre Commerce de Sedhiou, ARDS, DARD.
Number of beneficiaries: 80.000 people

The project

Southern Senegal, namely the region of Casamance, has been affected by the so called”Salt intrusion”, rare environmental phenomenon dangerously threatening societies. Atlantic tides flood over croplands contamining well waters. Most suffering communities are located in rural areas, where main activities are represented by agriculture, causing malnutrition, diseases and poverty. One of the biggest valley across Casamance river, Tanaff, tides erased 10.000 hectares of rice fields having its effects on 80.000 people. This forgotten region sees a 87% of its inhabitants suffering malnutrition, 92% poverty, 85 % of its children suffers growth delays with the highest rate of infant mortality; life expectation’s not passing 65 years-old and 60% of people suffers diseases due to the “salt intrusion” phenomenon.
The work consists in building a barrier at the entrance of the valley to stop floods and create a provision pond upriver, sending back 10.000 hectares of croplands, a decontamined water layer and giving birth to new working activities toghether with social development. On national level the project has to be adopted as a sample, turning around life of 80.000 inhabitants, in a long-lasting and sustainable way, realized gathering authorities and locals, giving them an integrated role through envolving and training programmes. It also earned several agreements among international science community, who often supported it, as well as Senegal local one with ministries, thanks to its sofisticated and complex features about organization and engeneering.
The highest goal is to give birth again to a high potential area, rich in resources, that faces at the same time difficulties such as salt phenomenon affecting life aspects as nutrition, health and economy. Thanks to its realization community will have back its activities and grant a better future to its youngest generations.


Engeneering Aspects

Local community already tried to implement the project, failing because of a lack in knowledge and technical skills; that is why it must be leaded through training processes and holding responsibilities. Dam planning in Casamance has an history of more than 50 attempts, some working and some not, and that analysis has let us check what has been made wrong and gave an idea on potentials of local technology. The sample project has to be intended as a repeatable one and to be rebuilted by locals in every valley, starting from appropriate skills for its construction estabilished once finished the first realization of the dam bridge.
The Dam Bridge differs from others projects for its stratified materials, each one having its own function: Salt filtering at once, as well as drainage aimed to lighten the structure and its structural containment. Raoul Vecchio planned on engeneering bases, supported by University academics , companies and behind the consult of organs operating in this branch, allowing the creation of a real sample that works as an anti- barrier, filtering water and desalining the valley.
Work’s lenght reaches 855 metres, with a highest point of 5,5 mts (from the bottom of the riverbed) and a shore minimum level of 1,5 mts. Dam works partially as a Bridge (so called Dam – Bridge by locals) "piercing” the whole structure to allow the flow of rain water stored in the valley. This is a successful process based on efficient management and a detailed hydraulic equilibrium. The Analysis of previous projects resulted in failures due to management difficulties in cleansing of valleys. Dam’s furthermore equipped with emergency drain pipes across shores, activated in case of unpredicted floods, so avoiding floods of surrounding villages. Work has been planned from an hydraulic and structural point of view, enriched by urban, social, environmental, architectural and agricultural researches.

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Saline Intrusion Phenomenon

The phenomenon mentioned above also affects other rivers, not just Casamance, with same hydrological and Geological characteristics, and represents one among primary causes of lacking food and economic conditions, linked to agricultural process. This rare phenomenon has been analyzed through an important bibliographic survey (showing a lack of datas and competent studies on the branch), but most of all thanks to evaluations of the area cooperated by Academics, authorities and organizations linked to hydraulic field.
The so called “Saline Intrusion” began with drought in Sahel region and its increasing evapo-transpiration. Those changes, filed since 1970, hydrologically transformed the Casamance river and its resources. Phenomenon intesifies due to the shape of the estuary as well as the increase of salt deposit is due to morphology of the territory, observed at different depths, and ending with fluvial sections shaped as “bottlenecks”. This Phenomenon is the result of three macro aspects: tides propagation within the pond, morphology of the territory, climate changes. Those parameters gave birth to an anomalous increase of the salinity in Casamance pond, that reaches in some areas, 135 grammes salt per litre during dry season; 5 times more salted than sea level, devastating natural, fluvial and floral ecosystem: coastal erosion, undergound acidification, contamination of water layer, death of fishes, loss of rice fileds and the pond desertification are all consequences of the phenomenon. Dramatic effect negatively echoes upon society and environment, causing a true emergency.
University of TUDelf confirmed the irreversibility of the saline intrusion through the scientific model of Savenjie, as to have a regular salinity it would be necessary an amount of rains three times higher than actual one…very hard to deal with for obvious reasons. Local and single interventions in valleys is the only way to improve environmental and social conditions. Pictures below underlines distribution of salinity along them as well as propagation of tides towards the pond.


Positive Impacts

Building the Dam will stop tides access, creating an unpriver pond obtained with the collection of water coming from rain and undergound layer. Once fullfilled, after rainy season, the Dam will melt acids and salt deposits contained beneath the ground, drained during dry season or in some particular hydraulic conditions. Drain of water’s so permitting a cleansing of the valley; A progressive process, that increases year after year and alwyas gets more efficient, aimed to give back the maximum extesion of croplands (10.000 hectares).
Two years of hard rains would be sufficient to achive initial results in agricultural activity of rice fields and reforestation of the pond. The evaluation on restoring a maximum of 10.000 hectares would satisfy alimentary need of 80.000 inhabitants creating an actual economic boom in the area.

In addition to those changes, the pond will allow:
- the recuperation of the Balmadou forest improving microclimate conditions and safeguarding endangered tree species.
- the recuperation of emigrated animals, due to the previous absence of water and plant life.
- the empowering of fruit production for food integration and economic development.
- the contamination and lifting up of water undergound layer.

This last feature’s an important one in most affected subjects (such as children and older people), and the presence of salt killed microbes contamining wells and layers water in facts. 60% of diseases and local infections are caused by that. The pond cleans the layer in a natural and sustainble way. As natural as the lifting up of the layer that will occur thanks to the project and collecting more water inside wells.
Last, it has a strong infrastructural impact. More than 25 villages are isolated, forcing people to walk more than 18 km to reach hospitals and markets. Thanks to the Dam Bridge the distance will be reduced to only of 2 kms, spontaneously generating social and economic relationship, unaffordable before.


Tanaff Valley

Tanaff valley takes its name from the ancient and most representative village, constiting in an hydraulic pond actually called Tanaff. Its hydraulic network has an immense potential, extended beyond 95 kms on 450 square kms, divided in platforms dedicated to tree-culture, forests with a declivity of the valley next to zero, formed by a clay and sandy soil. Thanks to these characteristics, this soil represented one of the most productive areas for rice production with more than 15.000 hectares of croplands before dryness in 1965 and salt intrusion. Along the valley live more than 50.000 people from more than 150 villages, but its agricultural potentials reach 80.000 individuals. It extends, from a hydrological point of view, on villages of Sanoufily and Sambacounda (on rispective shores) up to 10 km away from borders of Guinea Bissau.
Tanaff’s a crucial check-point, as form Ziguinchor town (informal capital city of Casamance)is possible to reach the second most important urban centre of Kolda, driving the N6 domestic route and without crossing the Casamance River.
The cultural basin of the valley has an extraordinay variety of 7 ethnic groups, mixed in harmony and peace.



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Progress

General cooperation system previewed a direct involvement of every interested association: us, beneficiaries, local administrations and technical bureaux in the region. Although our will, together with beneficiaries’one, was to support the project through right resources and availabilities, local administrations, composed by 5 elements, had first to gather municipalities in order to develop the burocratic process of realization of the work place, being an infrastructural project aimed to benefit communites and built on pubblic lands. Unfortunately municipalities haven’t been able to raise pubblic interest, even pushed by Regional Governement and technical bureaux. Community set for dissense invain several times, marching and protesting to push administrations to carry out the project and boost its realization. Due to some delays, population’s suffering in the meantime, and this moved Raoul Vecchio to denounce the organization of incapability to highest authorities in the Country, that welcomed him to talk about the project. He met 8 ministries, debated with Presidency asking for a state direct involvment at the place of local administrations. President and prime minister, aware of the importance of the project, ufficially encharged the ministry of agriculture to cooperate with Balouo Salo and other ministries involved and enhanced. (Hydraulic, Environmental and Infrastructural one). The project widens then its cooperation at ministerial level, still waiting for an answer to our request on acting procedures and depending on involved ministries.




Supports

Thousands of people among academics, professionals and more, supported our goal. We would like to thank those but it’s hard to name them one by one, that’s why, from the conscoiusness of their altruistic act, we send a big thank in the name of beneficiaries communities.
Below you will find a list of some companies that contributed to the project donating goods or services:
Ambasciata della Repubblica del Senegal in Italia, Sedhiou Gouvernment, ARDS, Chambre de Commerce de Sedhiou, PPDC, Graphiservice, Area, Archicart, Archimede Stampe, Tipografia Gullotta, Ruwa srl, Associazione L'Impulso, Jamm Senegal, Aldemaro Onlus, Lions Club Faro Biscari, Fondazione FL, Cogiatech, Remax CT, Gori Petrol Group, Archilovers, Miseria & Nobiltà, Pizzeria Balsamo, Calcio Catania, Katanè Palace, CUS CT, Galmar Premiazioni, Hotel Bester Western, ACR Messina, CARA di Mineo, In/Arch Sicilia, Università di CT, Archilovers, Pixartprinting, Rizzotti, Nero Sicilia, Città della Scienza CT, CA2 Lab, UCEI, Stilolinea, Millegradi, Consolato della Repubblica del Senegal in Sicilia.


UCEI Balouo Salo
The Union of Italian Jewish Communities contributes to the realization of the "A Bridge for Life" project with funds deriving from the 8x1000 UCEI

Awards

  • Sicily International Solidarity Award 2015 - Federico II - Rosolini (SR) )
  • Award Giovanni Lorenzin 2015 on the management of water resources in developing countries - Portogruaro (VE)


Gallery

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