Search

During the last 20 years, floods have become a major hazard in West Africa, particularly in the Sahelian belt, affecting livelihoods, infrastructure and production systems, and hence heavily impacting on sustainable development. The Sendai Framework for Disaster Risk Reduction 2015–2030 recognized Climate Services (CS) as a powerful tool for more effective disaster preparedness. The European research and innovation Roadmap for CS expands their contribution, particularly “hydrometeorological services”, to the Sendai Framework. From this convergence, Hydrometeorological Early Warning Systems (EWS) become a strategic target and a building block of preparedness to hydrometeorological risks in developed and developing countries. In West Africa, EWS for floods are in place only for the main rivers and are conceived mainly top-down and hazard centered, lacking links with exposed communities and expected impacts. These gaps reduce the effectiveness of a flood EWS, while engaging local communities since de beginning through a co-production process can improve the effectiveness and ensure better response in case of alert.Our study aims to present the lessons learnt from the set-up of a Community and Impact Based Flood EWS on the Sirba River in Niger. The service was developed with stakeholders at different levels, leveraging on existing resources and knowledge, using simple but effective approaches and integrating state-of-the-art hydro-meteorological science in a decisional scheme of Sahelian rural areas. This mechanism can be replicable in different contexts characterized by knowledge and structural deficits, by creating a better capacity to exchange data and information and by directly connecting available technical capabilities with the local level. The participatory approach allowed the beneficiaries to define the rules of the system, which, in any case, needed to be consistent with the national legislation and internationally recognized best practices.The study suggests that it is not necessary to develop complex forecasting tools, while it can be preferable to enhance those already operating and calibrate them on the local scale through risk thresholds, field observations and potential impacts using flood scenarios. The strength of simplicity also lies in not having to spread complex messages, but simply the reference risk scenario, and finally its color-code (according to the international standards of ISO 22324:2015), which already embeds all other information including potential impacts. The simple and integrated approach illustrated in this case study, bridging the gap between top-down and bottom-up approaches, can inspire Governments, local administrations and development partners to invest in the improvement of existing tools and knowledge and in strengthening cooperation, collaboration and coordination to reduce hazards’ impacts and sustain the development of rural and urban areas.

International audience; Niamey, the capital of Niger, is particularly prone to floods, since it is on the banks of the Niger River, which in its middle basin has two flood peaks: one in summer (the red flood) and one in winter (the black flood). In 2020, the Niger River in Niamey reached its all-time highest levels following an abundant rainy season. On the other hand, the floods in Niamey have been particularly frequent in the last decade, a symptom of a change in hydroclimatic behaviour already observed since the end of the great droughts of the 1970s and 1980s and which is identified with the name of Sahelian Paradox. This study, starting from the analysis of the 2020 flood and from the update of the rating curve of the Niamey hydrometric station, analyses the rainfall–runoff relationship on the Sahelian basins of the Medium Niger River Basin (MNRB) that are at the origin of the local flood. The comparative analysis of runoffs, annual maximum flows (AMAX) and runoff coefficients with various rainfall indices calculated on gridded datasets allowed to hydroclimatically characterise the last decade as a different period from the wet one before the drought, the dry one and the post-drought one. Compared to the last one, the current period is characterised by a sustained increase in hydrological indicators (AMAX +27%) consistent with the increase in both the accumulation of precipitation (+11%) and the number (+51%) and magnitude (+54%) of extreme events in the MNRB. Furthermore, a greater concentration of rainfall and extremes (+78%) in August contributes to reinforcing the red flood’s positive anomalies (+2.23 st.dev in 2020). The study indicates that under these conditions the frequency of extreme hydrological events in Niamey will tend to increase further also because of the concurrence of drivers such as river-bed silting and levee effects. Consequently, the study concludes with the need for a comprehensive flood-risk assessment on the Niamey city that considers both recent hydroclimatic trends and urbanisation dynamics in flood zones hence defining the most appropriate risk-reduction strategies.

Cet ouvrage visait à montrer, à travers le cas de la région Dosso (Niger), comment il est possible d'améliorer la gestion locale du risque hydroclimatique en milieu rural au moyen d'analyses et d'évaluations des risques et de mesures d'adaptation appropriées. Les onze chapitres présentent la sécheresse agricole, les précipitations intenses et les inondations fluviales qui menacent les établissements humains et les moyens de subsistance de la population rurale de cette région, en réduisant la sécurité alimentaire et entravant le développement durable. Les températures, les pluies intenses, les séquences sèches devraient augmenter dans les années à venir et leurs impacts sur les communautés rurales sont destinés à se répéter et à s'aggraver s'ils ne sont pas traités par des mesures adéquates. Ces menaces se traduisent par des impacts sur les communautés locales. Dans la région de Dosso, ce ne sont pas les villes qui sont les plus touchées par les inondations mais les villages administratifs et les hameaux, où 70 % des dégâts aux habitations s'accumulent. Au cours des vingt dernières années, ces localités semblent subir une transformation rapide. Tout d'abord, elles se développent plus rapidement (5,4 % en moyenne annuelle) que les villes (3,0 %). Ensuite les bâtiments utilisent de plus en plus des toitures en tôle : + 14 % en moyenne annuelle dans les villages administratifs et + 15 % en moyenne annuelle dans les hameaux. Cependant, cette consolidation positive du cadre bâti n'est pas suffisante pour protéger les maisons des inondations pluviales.

En Afrique tropicale la réduction du risque hydro-climatique peine à devenir une politique publique. La Région de Dosso au Niger (31 000 km2, deux millions d'habitants) a été inondée et frappée par la sécheresse à plusieurs reprises durant les dernières années. Alors, pour mieux comprendre et maîtriser ces aléas les changements climatiques d'ici au 2030 sont caractérisées à l'échelle locale. La base de données sur les inondations est transférée dans une archive ouverte. La dynamique spatiale des localités rurales est observée durant les 20 dernières années, L'analyse-évaluation du risque d'inondation et de sécheresse est développée à l'échelle régionale, communale et de localité rurale. Des services climatologiques sont offerts aux petits producteurs ruraux. Les méthodes proposées utilisent des informations en libre accès et sont donc aisément reproductibles dans d'autres régions du Pays et d'Afrique francophone. Ce livre présente des outils pour connaître et gérer le risque hydro-climatique à l'échelle locale (Sous Presse).

In the tropics, rural areas are still the place where many people live, despite ongoing urbanization [...]

Highlights ● Hydraulic modelling and satellite imagery enable hazard and exposure mapping. ● Local knowledge enables better understanding of hazards and their impacts. ● Benefit/cost and opportunity analysis support decision-making in risk treatment., In tropical regions, heavy precipitations may lead to catastrophic flooding due to the degradation of catchments and the expansion of settlements in flood prone zones. In the current situation, where information on rainfall and exposed assets is either scant, or requires significant time to be collected, pluvial flood risk assessments are conducted using participatory tools, without any scientific support. Another option is to use satellite precipitation products, digital terrain models and satellite images at high to moderate-resolution. However, these datasets do not reach the required accuracy at the local scale. Consequently, the potential damages and the evaluation component of risk assessment are often missing. Risk evaluation is pivotal for informed decision-making, with regards to the choice of treating or accepting the risk, implementing more effective measures, and for determining the safest areas for development. We proposed an improved method for assessing the risk of pluvial floods, which merges local and scientific knowledge and is consistent with the ISO 31010 standard. The method was successfully applied in five rural settlements in Niger and can be replicated in areas where information is scarce., Graphical abstract Improved method for assessing the risk of pluvial flooding locally. Its application in five rural settlements demonstrates its usefulness in decision-making regarding risk treatment and built-up expansion in safe areas.Image, graphical abstract

Introduzione generale al libro "Risque et adaptation climatique dans la région de Dosso au Niger" prodotto nell'ambito del progetto ANADIA2.

Disaster risk reduction in rural Africa can contribute to reducing poverty and food insecurity if included in local development plans (LDPs). Five years after the Sendai Framework for Disaster Risk Reduction (DRR), we do not know how much risk reduction is practiced in rural Africa. The aim of this assessment is to ascertain the state of mainstreaming DRR in development planning in the rural jurisdictions of tropical Africa. One hundred and ninety-four plans of 21 countries are considered. Ten characteristics of the plans are examined: Climate trends, hydro-climatic hazards, vulnerability and risk assessments, alignment with Sendai Framework, vision, strategies and objectives, DRR actions, internal consistency, DRR relevance and funding sources, local and technical knowledge integration, public participation. It is found that local climatic characterization is almost always absent and risk reduction is an objective of the plans in one case out of three. Prevention actions prevail over those of preparedness. There is poor participation in the plan preparation process and this limits the implementation of the actions. A modification of the national guidelines on the preparation of LDPs, the orientation of official development assistance towards supporting climate services and the training of local planners, together with the increase of financial resources in local jurisdictions are essential for improving DRR at local scale.

Floods have recently become a major hazard in West Africa (WA) in terms of both their magnitude and frequency. They affect livelihoods, infrastructure and production systems, hence impacting on Sustainable Development (SD). Early Warning Systems (EWS) for floods that properly address all four EWS components, while also being community and impact-based, do not yet exist in WA. Existing systems address only the main rivers, are conceived in a top-down manner and are hazard-centered. This study on the Sirba river in Niger aims to demonstrate that an operational community and impact-based EWS for floods can be set up by leveraging the existing tools, local stakeholders and knowledge. The main finding of the study is that bridging the gap between top-down and bottom-up approaches is possible by directly connecting the available technical capabilities with the local level through a participatory approach. This allows the beneficiaries to define the rules that will develop the whole system, strengthening their ability to understand the information and take action. Moreover, the integration of hydrological forecasts and observations with the community monitoring and preparedness system provides a lead time suitable for operational decision-making at national and local levels. The study points out the need for the commitment of governments to the transboundary sharing of flood information for EWS and SD.

The current literature links flood exposure and the consequent damage in the sub-Saharan Africa to urban expansion. The main implication of this pertains to the fact that cities are the target of flood risk reduction. However, our knowledge of the built-up area expansion–flood damage nexus is still too scarce to support any risk reduction policy at the local scale. The objective of this study is to reconsider the link between urban expansion and flood damage widening the observation to rural settlements with open access information alternative to global datasets on flood damages and moderate resolution satellite images. Using very high-resolution satellite images accessible via Google Earth Pro, the expansion of 122 flooded settlements in the Dosso region (Niger) during the past 20 years is evaluated. Spatial dynamics is then compared with the rate of collapsed houses due to flooding. Finally, house collapses and retrofitting are compared. We discovered that cities expand at faster rates and with an opposite trend to that reported by the global datasets. However, hamlets and villages expand even more rapidly and suffer more house collapses than rural towns and cities. House consolidation is quicker than the settlement expansion but this is not sufficient to reduce damage from pluvial flooding. The proportion of the Poor to the total number of inhabitants in rural settlements is three times higher than that in urban settlements. Environmental justice is, therefore, not just an urban issue but a rural urgency.

South of the Sahara, flood vulnerability and risk assessments at local level rarely identify the exposed areas according to the probability of flooding or the actions in place, or localize the exposed items. They are, therefore, of little use for local development, risk prevention, and contingency planning. The aim of this article is to assess the flood risk, providing useful information for local planning and an assessment methodology useful for other case studies. As a result, the first step involves identifying the information required by the local plans most used south of the Sahara. Four rural communities in Niger, frequently flooded by the Sirba River, are then considered. The risk is the product of the probability of a flood multiplied by the potential damage. Local knowledge and knowledge derived from a hydraulic numerical model, digital terrain model, very high resolution multispectral orthoimages, and daily precipitation are used. The assessment identifies the probability of fluvial and pluvial flooding, the exposed areas, the position, quantity, type, replacement value of exposed items, and the risk level according to three flooding scenarios. Fifteen actions are suggested to reduce the risk and to turn adversity into opportunity.

In Sahelian countries, a vast number of people are still affected every year by flood despite the efforts to prevent or mitigate these catastrophic events. This phenomenon is exacerbated by the incessant population growth and the increase of extreme natural events. Hence, the development of flood management strategies such as flood hazard mapping and Early Warning Systems has become a crucial objective for the affected nations. This study presents a comprehensive hazard assessment of the Nigerien reach of the Sirba River, the main tributary Middle Niger River. Hazard thresholds were defined both on hydrological analysis and field effects, according to national guidelines. Non-stationary analyses were carried out to consider changes in the hydrological behavior of the Sirba basin over time. Data from topographical land surveys and discharge gauges collected during the 2018 dry and wet seasons were used to implement the hydraulic numerical model of the analyzed reach. The use of the proposed hydraulic model allowed the delineation of flood hazard maps as well the calculation of the flood propagation time from the upstream hydrometric station and the validation of the rating curves of the two gauging sites. These significative outcomes will allow the implementation of the Early Warning System for the river flood hazard and risk reduction plans preparation for each settlement.

Hydro-climatic risk assessments at the regional scale are of little use in the risk treatment decision-making process when they are only based on local or scientific knowledge and when they deal with a single risk at a time. Local and scientific knowledge can be combined in a multi-hazard risk assessment to contribute to sustainable rural development. The aim of this article was to develop a multi-hazard risk assessment at the regional scale which classifies communities according to the risk level, proposes risk treatment actions, and can be replicated in the agropastoral, semi-arid Tropics. The level of multi-hazard risk of 13 communities of Hodh Chargui (Mauritania) exposed to meteorological, hydrological, and agricultural drought, as well as heavy precipitations, was ascertained with an index composed of 48 indicators representing hazard, exposure, vulnerability, and adaptive capacity. Community meetings and visits to exposed items enabled specific indicators to be identified. Scientific knowledge was used to determine the hazard with Climate Hazards Group Infra-Red Precipitation with Station (CHIRPS) and Tropical Rainfall Measuring Mission (TRMM) datasets, Landsat images, and the method used to rank the communities. The northern communities are at greater risk of agricultural drought and those at the foot of the uplands are more at risk of heavy rains and consequent flash floods. The assessment proposes 12 types of actions to treat the risk in the six communities with severe and high multi-hazard risk.

International aid for climate change adaptation in West Africa is increasing exponentially, but our understanding of hydroclimatic risks is not keeping pace with that increase. The aim of this article is to develop a multihazard risk assessment on a regional scale based on existing information that can be repeated over time and space and that will be useful during decision-making processes. This assessment was conducted in Dosso (Niger), the region most hit by flooding in the country, with the highest hydroclimatic risk in West Africa. The assessment characterizes the climate, identifies hazards, and analyzes multihazard risk over the 2011&ndash, 2017 period for each of the region&rsquo, s 43 municipalities. Hazards and risk level are compared to the intervention areas and actions of 6 municipal development plans and 12 adaptation and resilience projects. Over the past seven years, heavy precipitation and dry spells in the Dosso region have been more frequent than during the previous 30-year period. As many as 606 settlements have been repeatedly hit and 15 municipalities are classified as being at elevated-to-severe multihazard risk. The geographical distribution of the adaptation and resilience projects does not reflect the risk level. A third of the local development plans examined propose actions that are inconsistent with the main hydroclimatic threats.

This book aims to inspire decision makers and practitioners to change their approach to climate planning in the tropics through the application of modern technologies for characterizing local climate and tracking vulnerability and risk, and using decision-making tools. Drawing on 16 case studies conducted mainly in the Caribbean, Central America, Western and Eastern Africa, and South East Asia it is shown how successful integration of traditional and modern knowledge can enhance disaster risk reduction and adaptation to climate change in the tropics. The case studies encompass both rural and urban settings and cover different scales: rural communities, cities, and regions. In addition, the book looks to the future of planning by addressing topics of major importance, including residual risk integration in local development plans, damage insurance and the potential role of climate vulnerability reduction credits. In many regions of the tropics, climate planning is growing but has still very low quality. This book identifies the weaknesses and proposes effective solutions.

In the Tropics, a significant increase in the number of cities provided with climate plans by 2020, as announced in the 11th Sustainable development goal of the United Nations, requires an unprecedented effort. To achieve it, we have to simplify the planning process and improve the quality of the plans. The aim of this book was to collect methods and experiences to inspire the simplification of the planning process and increase the quality of climate planning. We focused attention on the three critical phases of the planning process: analysis, decision making in planning, climate measures. Sixteen case studies from Ethiopia, Haiti, Malawi, Mexico, Niger, Senegal, Tanzania and Thailand cover automatic weather stations in remote areas, rainfall estimation gridded datasets, open data for vulnerability index to climate change, early warning systems, quality of climate plans index, multi-risk local assessment, flooding risk evaluation method, backcasting, spatial dimension in disaster risk reduction and resilience, gasification stoves, index-based insurance and vulnerability risk credit. After indicating the possible analyses, 19 recommendations were supplied to the United Nations SDGs monitoring system, the national weather services and those responsible for natural risks, to the Development banks, Official development aid and the research institutions.

In the last seven years, the number of plans with climate measures for tropical cities has increased 2.3 times compared to the previous seven years as a result of the initiatives of central and local governments, multi-bilateral development aid and development banks. The plans matter in achieving the 11th United Nations’ Sustainable development goal. Therefore, the objective of this chapter is to ascertain the relevance and quality of climate planning in large and medium-sized cities in the Tropics. The chapter proposes and applies the QCPI-Quality of Climate Plans Index, consisting of 10 indicators (characterization of climate, number, quantification, relevance, potential impact, cost, funding sources, timetable and responsibility of measures, implementation monitoring and reporting). It is revealed that 338 tropical cities currently have a local development, emergency, master, mitigation, adaptation, risk reduction plan or a resilience or smart city strategy. These tools were unquestionably more common in large cities, especially in OCDE and BRICS countries, while they were rare in Developing Countries. Local development plans (Municipal development, general, comprehensive) were the most common in medium-sized cities, along with those with the lowest quality, while stand-alone strategies and plans (resilience, mitigation, sustainable, adaptation), applied mostly in big cities, present much higher quality.

In the rural Tropics, the participatory risk assessment, based on local knowledge only, is very widespread. This practice is appropriate for hazard identification and for raising the awareness of local communities in relation to the importance of risk reduction, but it is still imprecise in determining risk level, ranking and treatment in a context of climate change, activities in which technical knowledge is unavoidable. Integration of local and technical-scientific knowledge within the framework of an encoded risk assessment method (ISO 31010), could favour more effective decision making with regard to risk reduction. The aim of this chapter is to verify the applicability of a multi-risk local assessment-MLA which combines local knowledge (participatory workshop, transect walk, hazard and resource mapping, disaster historical profile) and scientific knowledge (climate downscaling modelling, hazard probability and scenarios, potential damages, residual risk). The test is carried out in two villages of the Western Niger, particularly exposed to flooding and agricultural drought. The risk (hazard probability * potential damages) is identified, analysed (level of risk) and evaluated (residual risk, adaptation measures compared with potential damage costs). The MLA is feasible. The two villages, while bordering on one another, have a different risk ranking. Depending on the village, the risk treatment could reduce the risk level to 17 and to 41% of the current risk, with costs equating to 34 and 28% of the respective potential damages.

In Least Developed tropical Countries, the vulnerability assessment to climate change (CC) at local scale follows an indicator-based approach and uses information gathered mainly through household surveys or focus groups. Conceived in this way, the vulnerability assessment is rarely repeatable in time, cannot be compared with those carried out in other contexts and usually has low spatial coverage. The growing availability of open data at municipal level, routinely collected, now allows us to switch to vulnerability tracking (continuous, low cost, consistent with global monitoring systems). The aim of this chapter is to propose and verify the applicability of a VICC-Vulnerability Index to Climate Change on a municipal scale for Haiti. The chapter identifies open data on national, departmental and municipal scale, selects the information on a municipal scale on the basis of quality, identifies the indicators, evaluates the robustness of the index and measures it. The index consists of 10 indicators created using information relating to monthly precipitations, population density, flood prone areas, crop deficit, farmers for self-consumption, rural accessibility, local plans for CC adaptation, irrigated agriculture and cholera incidence. This information is gathered for the 125 mainly rural municipalities of Haiti. The description and discussion of the results is followed by suggestions to improve the index aimed at donors, local authorities and users.

In the last seven years, tropical cities with a climate plan have tripled compared to the previous seven years. According to the 11th United Nations’ Sustainable Development Goal, climate planning should significantly increase by 2030. The Sendai framework for disaster risk reduction (2015) and the New urban agenda signed in Quito (2016) indicate how to achieve this goal through analysis, categories of plans and specific measures. This chapter identifies the main obstacles to the significant increase in tropical human settlements with a climate plan and the possible solutions. First of all, the distribution and trend at 2030 of tropical human settlements are ascertained. Then local access to information on damage, hazard, exposure, vulnerability and risk, and the consideration of these aspects in the national guides to local climate planning are verified. Lastly, the categories of plans and climate measures recommended by the United Nations are compared with those that are most common today, using a database of 401 climate plans for 338 tropical cities relating to 41 countries. The chapter highlights the fact that the prescription for treating tropical cities affected by climate change has been prepared without an accurate diagnosis. Significantly increasing climate planning must consider that small-medium human settlements in the Tropics will prevail at least until 2030. And most effort will be required from Developing and Least Developed Countries. The recommendations of the United Nations concerning the preliminary analyses ignore the fact that local authorities usually do not have access to the necessary information. Climate plans and recommended measures are not those currently in use. We propose three areas of action to facilitate the mainstreaming of the recommendations in the tropical context. They require a renewal of the local planning process if we intend to reach the 11th SDG by 2030.

In recent years, the number of large subtropical and tropical cities with defined climate plans has increased as a result of the initiatives of local governments, multi-bilateral development aid and development banks. Surveys carried out to date on climate planning consider the overall cities, at times by continent, without underscoring those that present planning deficiencies. For instance, we have no idea whether the cities that are most affected by hydro-meteorological and climatic disasters have plans, nor if their climate plans are ready to be implemented. Clarifying these aspects would strengthen the foundation of the current discussion on the United Nations' Sustainable Development Goals 2016-2030. Hence, the objective of this chapter is to ascertain the relevance and quality of climate planning in large subtropical and tropical cities populated by over 1 million inhabitants. Our survey found 344 large cities in the two climate zones concerned, and 82 of these have mitigation, adaptation, resilience or emergency plans, strategies or policies. We verified the relevance of these tools for the climate zones concerned, the type of economy and the frequency of hydro-meteorological and climate-related disasters. The quality of plans was assessed, ensuring that they had taken climate characterisation into account, that every measure was managed by a designated agency or office, and that funds were secured for implementing measures, as well as a monitoring and reporting sytem was defined. The analysis of collected information underscores considerable differences between large cities in terms of per capita greenhouse gas emissions (which were double in the subtropics relative to the tropics) and exposure to hazards (which were greater in the subtropical zone). Emergency and mitigation plans were the most common, while adaptation plans and resilience strategies were more unusual. The relevance of plans is still weak, given that barely 1/4 of the large cities had a plan. Plans were unquestionably more common in the subtropics, especially in OECD countries and in the BRICS, while they were absent in the Least Developed Countries (LDCs), despite the presence of large cities that have been repeatedly affected by hydro-meteorological and climate-related disasters. Planning quality was good for 30% of cities only. In the remaining 70% of cities, climate characterisation was briefly defined; the planning process was fully funded by multi-bilateral development aid; measures were without a clear manager; cost, funds and monitoring of measures were not specified. Thus the indication being that local plans were still scarcely action-oriented. Hence, the fact that two sustainable development goals (# 11 and 13) address human settlements and climate change, respectively, especially through assistance to LCDs, seems justified.

The Tillaberi region (population 2.7 million, 97,250 km2) is the hinterland of the Niger's capital city and the second most susceptible region to flooding of the country, with 416 settlements hit from 2008 to 2013. This chapter aims to present the potential benefits of flood risk assessment at municipal scale: a tool that can help local authorities in disaster risk reduction. Risk (R) is considered here a function of Hazard (H), Exposure (E) and Damages (D) according the equation R = H * E * D. Risk is measured using six indicators. The probability in each year to have e rain causing settlement flooding is measured for each municipality using daily rainfall from meteorological stations (1981-2010) and three-hourly Tropical Rainfall Measuring Mission (TRMM) datasets by NOAA (1998-2011). Settlements flooded (E), people affected, homes destroyed, fields flooded and livestock killed (D) are sourced from Niger's early warning system and disaster prevention unit (EWS DP), all errors corrected and units of measurement standardised. From the results, it emerged that 765 settlements have been flooded between 1998 and 2013. Contrary to what one might expect, the floods caused by the swelling of the River Niger hit few settlements. Most of the areas susceptible to flooding are located in the vast Bosso and Maouri dallols, two fossil rivers that run from Mali towards Niger for over 300 km. The right-bank tributaries of the Niger and along the minor hydrographic network are the next most affected areas. 95 settlements were hit more than once and 19 flooded in two or more consecutive years. Seven municipalities out of 41 are at very high or high risk of being flooded. These are crossed by the River Niger or by its main tributaries on the right bank, by the Ouallam intermittent creek or the Bosso dallol. Seven municipalities show damage in three areas (people, dwellings, fields).

Flood mapping is still rare in the large cities South of Sahara. The lack of information on the characteristics of floods, the orography of the sites and the receptors hampers its production. However, even with scant information, it is possible to create preliminary risk mapping. This tool can be used by local administrations in decision making on emergency plans or on climate change (CC) action plans. From 2010 onwards the River Niger at Niamey (1.1 million inhabitants, 123 km2 in 2014) swelled at unseasonal times. That new river flood pattern can be linked to CC. Each flooding event affected thousands of people and homes. The unceasing development of areas that did not seem to be flood prone in the past is the main cause of these impacts. These areas require special measures if further impact is to be avoided in the future. This chapter presents the flood risk preliminary map of Niamey 1:20,000. The map is built up using an historic approach (flooded area derived from satellite images) and considering risk (R) as the result of hazard (H) and damage (D), R = H * D. Risk is measured according to two scenarios: medium and high probability of flooding. The inverse of the return period of river and pluvial flooding (H) and the potential damage to buildings and crops according the water depth are used. Information to measure risk components is sourced by daily rainfall and daily discharge of the River Niger from 1946 to 2014 and from high-resolution satellite images (2014). The risk map identifies hot spots for emergency and CC action planning. The fifth district alone contains 52% of the potential damage. 99% of the potential damage is concentrated within 225 hectars. Reinforcing existing embankments and constructing new ones to protect these areas seems more appropriate than resettlement. The cost of the works would equal the potential damage if it remains within 2,580 euro/ml.

L'objectif de ce chapitre est de vérifier la faisabilité et le potentiel d'une méthodologie alternative, qui emploie de prévalence des statistiques officielles à l'échelle de commune et qui part de la définition de risque en tant que « combinaison de la probabilité d'un événement et de ses conséquences négatives » , c'est-à-dire risque = aléa * exposition *dommages : R = A*E*D . Cette méthode manque de précision elle aussi, à cause des erreurs présentes dans l'enregistrement des dommages. Toutefois, elle contient plusieurs avantages par rapport aux précédents, étant simple et pouvant être mise à jour, appropriée par l'administration centrale et reproduite dans d'autres régions. L'application est proposée pour le Niger, l'un des pays les plus vulnérables aux catastrophes naturelles.

Population growth in a fragile rural environment: lessons from a case - study of Keita, Niger, 1958-2007 (Processo di popolamento di un ambiente rurale fragile: insegnamenti dal caso di Keita, Niger, 1958-2007). Niger is a perfect case for studying the consequences of population growth on renewable natural resources (Rnr) since it is the 5th fastest growing county demographically and the country with the highest share of rural population. Studies of population pressure on Niger’s Rnr have reached opposite findings. On the one hand, studies showed agricultural intensification, densification, and natural assisted regeneration. On the other hand, they also highlighted rain-fed crop encroachment on forest, bush, and grazing land; decrease in yields; and conflicts over access to water pasture. The coun- try is using a wide range of participatory tools for Rnr management and local development planning, but there has been little discussion on the effectiveness of these tools. This study seeks to find out what the trends regarding population growth and Rnr management are in Keita Department (5,000 sq km, pop. 258,000), a semi-arid, remote rural area where only 26% of the land is arable. 30 years of increasing population pressure (up to 86 inh. /sqkm in 2007) brought rain-fed crop encroachment on bush and rangeland. Intensification is absent both in rain-fed and in irrigated agriculture. Nevertheless, since 1984 the Keita rural development program has provided cereal selfsufficiency to at least one fourth of the 1988-2001-population growth and has reduced population pressure on forestland. At the present, municipal development plans have identified strategies based mainly on micro realizations. Road construction, microcredit, and higher value-added production are not being considered and strategies to secure the next generation’s access to crop, forest, and grazing land are not being defined.

In the region south of the Sahara, flooding is the most common natural hazard. Large cities are increasingly affected: 7 in the 1980s, 27 in the 1990s, 37 in the 2000s, and 7 more since 2010. Although many studies link this trend to climate change, our understanding of natural events is still too fragmentary to allow us to appreciate the correlation between precipitation and floods. When attempting to bridge this gap, we should also consider how rainfall affects a city’s entire watershed (which can be quite extensive). By contrast, the impact of flooding on places, goods, and people is much better understood. Such effects can be so extreme as to bring the economies of large cities to their knees. Over time, the concept of risk as a product of hazard and vulnerability has expanded to include exposure and climate change adaptation. Mapping flood risk is the first step towards identifying adaptation measures, yet only one of the 11 large cities most affected by floods has a detailed flood risk map. Three of the 11 have adopted climate change adaptation strategies and plans. The remaining eight cities use an array of tools whose impact on flood risk reduction is not yet detectable.

This chapter presents the adaptation baseline for flooding caused by extreme rains, sea level rise, and high tides brought on by climate change in the municipality of Maputo (1.1 million inhabitants in 2007, 347 km2). Adaptation measures were ascertained over the 57.4 km2 exposed to regular flooding through interviews with district and neighborhood officers and on-site inspections. The size of the areas exposed to flooding (16 % of the administrative surface), their dispersion in 21 fragments and the fact that many measures are not detectable by means of surveys has complicated the work. The importance of adaptation is defined for each exposed area on the basis of the physical, economic, social, and health consequences of its absence and is expressed as a figure that can be used in risk equations. A focus group set up with members of the environmental directorate of the municipality of Maputo identified short, medium, and long-term measures, prioritized those measures according to five criteria, and discussed the mainstreaming of adaptation in planning tools.

Chi ha visitato un'area remota di un paese povero si sarà forse chiesto come sia possibile sviluppare l'economia locale. Investire in queste zone può in effetti sembrare un azzardo, specie se è già difficile far crescere le aree più accessibili. Ciononostante, in molti casi si è visto che la rottura dell'isolamento ha ridotto la povertà. Ed è proprio ciò di cui il Niger ha bisogno. Le sue aree remote accolgono il 40% della popolazione. Da esse proviene la maggior parte dei prodotti d'esportazione. Ma un'economia così povera dove può trovare le risorse per spezzare l'isolamento? Il libro propone un'analisi regionale condotta con un apposito indice d'accessibilità della popolazione dipartimentale e diversi indicatori. L'andamento delle risorse naturali, della produzione, della popolazione e dell'accesso alle attrezzature è confrontato con le strategie di sviluppo nazionali e locali e con i programmi d'aiuto. Ciò consente di smontare alcuni cliché sulla relazione popolamento-intensificazione agricola, sulla rigenerazione della vegetazione, sugli strumenti di governance locale e di formulare suggerimenti per l'azione.