Economic Valuation of Ecosystem Services in Sahel's Wetlands: Case of Bourgou (Echinochloa stagnina) in the Inner Niger Delta

The Inner Niger Delta (IND) located in Mali provides several ecosystem services to Sahelian people. Among these services, the bourgou fields (Echinochloa stagnina) have a very high value for inhabitants' livelihood and biodiversity. The main objective of this study is to assess the economic value of bourgou ecosystem services in the IND. Specific objectives are to analyze ecosystem services from Echinochloa stagnina and the benefit-cost of its regeneration (plantation) in the IND. The adopted methodology is based on market price and benefit-cost approaches through analysis of collected data from conducted inhabitants' surveys in the circle of Youwarou located in Mali center. The findings show that each Bourgou producer farms on average 7 hectares that provide fish, pasture, livelihoods, and habitats for biodiversity as ecosystem services. The revenue received by bourgou producers with payment for access to pasture for 89,347 cattle is estimated at USD 150,674.78 (47,085,869 FCFA). The benefit of ecosystem services from bourgou is USD/ha 999.22 (312,257 FCFA/ha). To restore bourgou fields, 98.5% of producers are willing to pay USD 192.07 (60,023 FCFA) for it to improve seeds of 1 hectare cultivation. The bourgou culture is a green financing opportunity for income generation, ecosystem services restoration, and biodiversity conservation. Keywords: Bourgou, Biodiversity, Ecosystem services, Income, Inner Niger Delta DOI: 10.7176/JESD/14-17-03 Publication date: November 30th 202

Improving the Accuracy of Hydrodynamic Simulations in Data Scarce Environments Using Bayesian Model Averaging: A Case Study of the Inner Niger Delta, Mali, West Africa

In this paper, the study area was the Inner Niger Delta (IND) in Mali, West Africa. The IND is threatened by climate change, increasing irrigation, and dam operations. 2D hydrodynamic modelling was used to simulate water levels, discharge, and inundation extent in the IND. Three different digital elevation models (DEM) (SRTM, MERIT, and a DEM derived from satellite images were used as a source of elevation data. Six different models were created, with different sources of elevation data and different downstream boundary conditions. Given that the performance of the models varies according to the location in the IND, the variable under consideration and the performance criteria, Bayesian Model Averaging (BMA) was used to assess the relative performance of each of the six models. The BMA weights, along with deterministic performance measures, such as the Nash Sutcliffe coefficient (NS) and the Pearson’s correlation coefficient (r), provide quantitative evidence as to which model is the best when simulating a particular hydraulic variable at a particular location. After the models were combined with BMA, both discharge and water levels could be simulated with reasonable precision (NS > 0.8). The results of this work can contribute to the more efficient management of water resources in the IND

Development and assessment of non-linear and non-stationary seasonal rainfall forecast models for the Sirba watershed, West Africa

International audienceStudy region The Sirba watershed, Niger and Burkina Faso countries, West Africa. Study focus Water resources management in the Sahel region, West Africa, is extremely difficult because of high inter-annual rainfall variability. Unexpected floods and droughts often lead to severe humanitarian crises. Seasonal rainfall forecasting is one possible way to increase resilience to climate variability by providing information in advance about the amount of rainfall expected in each upcoming rainy season. Rainfall forecasting models often arbitrarily assume that rainfall is linked to predictors by a multiple linear regression with parameters that are independent of time and of predictor magnitude. Two probabilistic methods based on change point detection that allow the relationship to change according to time or rainfall magnitude were developed in this paper using normalized Bayes factors. Each method uses one of the following predictors: sea level pressure, air temperature and relative humidity. Method M1 allows for change in model parameters according to annual rainfall magnitude, while M2 allows for changes in model parameters with time. M1 and M2 were compared to the classical linear model with constant parameters (M3) and to the climatology (M4). New hydrological insights for the region The model that allows a change in the predictor\textendashpredictand relationship according to rainfall amplitude (M1) and uses air temperature as predictor is the best model for seasonal rainfall forecasting in the study area

A copula-based approach for assessing flood protection overtopping associated with a seasonal flood forecast in Niamey, West Africa

International audienc

A copula-based approach for assessing flood protection overtopping associated with a seasonal flood forecast in Niamey, West Africa.

International audienceFlood is one of the most important natural disasters that cause huge loss of life and properties everyyear around the world. Moreover, the International Federation of the Red Cross and Red CrescentSocieties pointed out that floods were by far the greatest cause of homelessness. In West Africa,many countries are damaged from flooding almost every season. Thus, this study aimed to set aseasonal flood forecast model and carried out an evaluation of the level of risk associated with eachseasonal forecast. HEC-RAS (Hydrologic Engineering Centers River Analysis System) was used todevelop a hydro-dynamical model of Niger river on a 160km reach (80km upstream to80kmdownstream of Niamey), then a simple risk measure was used to calculate the probability ofovertopping the flood protection dykes in Niamey. Results show that the hydro-dynamical modelreproduced well the rating curve over the period 2009-2014. A subsequent copula analysisdemonstrated a dependency between flow on the Niger river and flow on the Sirba River, the maintributary contributing to the seasonal flood at Niamey. The Gumbel copula was found to be the bestamong the tested 5 copulas to represent the dependency between peak flow on the main channel ofthe Niger River and concomitant flow on the Sirba river. It is found that for the six dykes theprobabilities of being overtopped by the flood range from very high (100%) to relatively low (16.67%) over the 34 years of simulation

Institutionalization of the water-energy-food-environment nexus in the Niger Basin

In less than one year the Niger Basin Authority, an intergovernmental body tasked with the sustainable development of the Niger waters and associated resources, passed the first ever nexus policy in a transboundary river basin, contributing to a true acceleration of change for improved water and associated development in the Niger River Basin. The guidelines were developed in close collaboration with the nine basin countries and complemented by a large capacity building program. Using the guidelines can reduce the threat of adverse impacts on the Basin’s shared water and land resources and save millions of dollars of investment funds, while meeting various Shared Vision objectives. Doing so can also help strengthen positive impacts, reduce crosssectoral constraints of single-sector solutions, and identify multisector solutions. Application of the nexus guidelines will increase the efficiency of natural resources use and support implementation and monitoring of (multipurpose) investments. If this can be achieved, the River of Rivers—thought to be the original meaning of the name Niger—will continue to enhance water, food and energy security, and environmental sustainability for generations to come. To support the application of the guidelines, the study team developed an online, simplified nexus assessment tool that is summarized in Appendix 4

Improving the Accuracy of Hydrodynamic Simulations in Data Scarce Environments Using Bayesian Model Averaging: A Case Study of the Inner Niger Delta, Mali, West Africa

In this paper, the study area was the Inner Niger Delta (IND) in Mali, West Africa. The IND is threatened by climate change, increasing irrigation, and dam operations. 2D hydrodynamic modelling was used to simulate water levels, discharge, and inundation extent in the IND. Three different digital elevation models (DEM) (SRTM, MERIT, and a DEM derived from satellite images were used as a source of elevation data. Six different models were created, with different sources of elevation data and different downstream boundary conditions. Given that the performance of the models varies according to the location in the IND, the variable under consideration and the performance criteria, Bayesian Model Averaging (BMA) was used to assess the relative performance of each of the six models. The BMA weights, along with deterministic performance measures, such as the Nash Sutcliffe coefficient (NS) and the Pearson’s correlation coefficient (r), provide quantitative evidence as to which model is the best when simulating a particular hydraulic variable at a particular location. After the models were combined with BMA, both discharge and water levels could be simulated with reasonable precision (NS > 0.8). The results of this work can contribute to the more efficient management of water resources in the IND

Quantifying the Sustainability of Water Availability for the Water‐Food‐Energy‐Ecosystem Nexus in the Niger River Basin

International audienceWater, food, energy, and the ecosystems they depend on interact with each other in highly complex and interlinked ways. These interdependencies can be traced particularly well in the context of a river basin, which is delineated by hydrological boundaries. The interactions are shaped by humans interacting with nature, and as such, a river basin can be characterized as a complex, coupled socioecological system. The Niger River Basin in West Africa is such a system, where water infrastructure development to meet growing water, food, and energy demands may threaten a productive and vulnerable basin ecosystem. These dynamic interactions remain poorly understood. Trade‐off analyses between different sectors and at different spatial scales are needed to support solution‐oriented policy analysis, particularly in transboundary basins. This study assesses the impact of climate and human/anthropogenic changes on the water, energy, food, and ecosystem sectors and characterizes the resulting trade‐offs through a set of generic metrics related to the sustainability of water availability. Results suggest that dam development can mitigate negative impacts from climate change on hydropower generation and also on ecosystem health to some extent

Water resources planning in the Upper Niger River basin: Are there gaps between water demand and supply?

Study region: The Upper Niger and Bani River basins in West Africa. Study focus: The growing demand for food, water, and energy led Mali and Guinea to develop ambitious hydropower and irrigation plans, including the construction of a new dam and the extension of irrigation schemes. These two developments will take place upstream of sensible ecosystem hotspots while the feasibility of development plans in terms of water availability and sustainability is questionable. Where agricultural development in past decades focused mainly on intensifying dry-season crops cultivation, future plans include extension in both the dry and wet seasons. New hydrological insights for the region: Today's irrigation demand corresponds to 7% of the average annual Niger discharge and could account to one third in 2045. An extension of irrigated agriculture is possible in the wet season, while extending dry-season cropping would be largely compromised with the one major existing Sélingué dam. An additional large Fomi or Moussako dam would not completely satisfy dry-season irrigation demands in the 2045 scenario but would reduce the estimated supply gap from 36% to 14%. However, discharge peaks may decrease by 40% reducing the inundated area in the Inner Niger Delta by 21%, while average annual discharge decreases by 30%. Sustainable development should therefore consider investments in water-saving irrigation and management practices to enhance the feasibility of the envisaged irrigation plans instead of completely relying on the construction of a flow regime altering dam. © 2019 The Author