Local and scientific knowledge integration for multi-risk assessment in rural Niger

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, particu-larly 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

Flood risk preliminary mapping in Niamey, Niger

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

Flood risk assessment at municipal level in the Tillabéri region, Niger

The Tillabéri 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)

Multihazard risk assessment for planning with climate in the Dosso Region, Niger

International aid for climate change adaptation inWest 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 2011–2017 period for each of the region’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

Multi-Hazard Risk Assessment at Community Level Integrating Local and Scientific Knowledge in the Hodh Chargui, Mauritania

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

Flood Assessment for Risk-informed Planning Along the Sirba River, Niger

South of the Sahara flood vulnerability and risk assessments at local level rarely identify the exposed areas according to the probability of flooding, the actions in place, 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

Participatory risk assessment of pluvial floods in four towns of Niger

Intense rainfalls in Sub-Saharan Africa are increasing in frequency. Land degradation, watercourses siltation, and flood defence failure turn these events into disastrous floods. Over the last decade flood risk assessments have been prepared to face these disasters. However, they have frequent limitations in design, accuracy, and completeness. The objectives of this study are (i) to integrate local and scientific knowledge into a participated pluvial flood risk assessment (ii) to identify assets and (iii) to estimate the potential impact and efficiency of risk-reduction measures. The assessment is developed in four rapidly expanding towns of Niger, flooded several times in recent years. Flood-prone areas and assets are identified according four flood scenarios using local knowledge, 2D hydraulic modelling, and visual photointerpretation of very-high-resolution satellite images. Risk-reduction measures are singled-out through public participation. The residual risk and benefit/cost analyses provide a decision-making tool to accept or treat risk. During the last decade the expansion of the four towns has been more rapid in flood-prone zones than in safe areas. Nowadays more than half of the housing stock could be flooded by rainfalls with 20 years return period. Catchment treatment and building retrofitting can reduce risk. from 100 to 29–82. Nevertheless, the benefit/cost of risk reduction is high for towns settled in small catchments only

Method for pluvial flood risk assessment in rural settlements characterised by scant information availability

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

Linee guida per la progettazione GIS nei paesi in via di sviluppo. Come scegliere la soluzione software appropriata al tipo di applicazione e all'utente

I GIS (Geographic Information System) sono sistemi informatizzati per l'acquisizione, la memorizzazione, il controllo, l'integrazione, l'elaborazione e la rappresentazione di dati che sono spazialmente riferiti alla superficie terrestre. Nei Paesi in via di sviluppo questi strumenti vengono impiegati oltre che nelle discipline tecniche e naturali in quelle umanistiche (archeologia, ecologia umana, studi linguistici, ecc), nelle scienze sociali ( geografia umana ed economica, economia, ecc. ) e in medicina (medicina sociale e professionale, epidemiologia ecc.). Le applicazioni vanno dall' inventario delle risorse naturali al monitoraggio attraverso la pianificazione territoriale, dalla programmazione economica e sociale alla gestione delle aree protette per arrivare alla protezione del patrimonio culturale e al turismo. Il mercato del software ha sviluppo negli ultimi anni un numero elevato di applicativi GIS. Il fenomeno della crescita nella disponibilità di software GIS non è stata accompagnata da un corrispondente aumento della conoscenza teorica e della competenza specifica necessaria. La mancanza di decisioni consapevoli sulle modalità di registrazione dei dati prese fin all'inizio, unita ad incomprensione delle capacità e delle limitazioni dei software, spesso rischiano di palesarsi a progetto finito. La tesi sviluppa delle linee guida che consentono di controllare le varie fasi della progettazione GIS considerando i vincoli specifici del contesto di applicazione e del progetto specifico. Inoltre si propone un modello di selezione di un software GIS che utilizza sia parametri qualitativi che quantitativ