From Management to Negotiation: Technical and Institutional Innovations for Integrated Water Resource Management in the Upper Comoé River Basin, Burkina Faso

This study focuses on the potential role of technical and institutional innovations for improving water management in a multi-user context in Burkina Faso. We focus on a system centered on three reservoirs that capture the waters of the Upper Comoé River Basin and servicing a diversity of users, including a sugar manufacturing company, a urban water supply utility, a farmer cooperative, and other downstream users. Due to variable and declining rainfall and expanding users’ needs, drastic fluctuations in water supply and demand occur during each dry season. A decision support tool was developed through participatory research to enable users to assess the impact of alternative release and diversion schedules on deficits faced by each user. The tool is meant to be applied in the context of consultative planning by a local user committee that has been created by a new national integrated water management policy. We contend that both solid science and good governance are instrumental in realizing efficient and equitable water management and adaptation to climate variability and change. But, while modeling tools and negotiation platforms may assist users in managing climate risk, they also introduce additional uncertainties into the deliberative process. It is therefore imperative to understand how these technological and institutional innovations frame water use issues and decisions to ensure that such framing is consistent with the goals of integrated water resource management.     

Carbon Sequestration Potential and Marketable Carbon Value of Smallholder Agroforestry Parklands Across Climatic Zones of Burkina Faso: Current Status and Way Forward for REDD+ Implementation

Agroforestry plays an important role in climate mitigation through atmospheric carbon removal by photosynthetic activity of tree. However, the carbon sequestration potential of smallholder’s agroforestry’s parklands is not well documented in Burkina Faso. Therefore, agroforestry parkland of smallholders’ farmers in three climatic zones was studied. Thirty household farmlands in each climatic zone representing about 35 ha were selected on which systematic woody species inventory and dendrometry data collections were undertaken. Nondestructive method using fitted allometrics equations was used to compute carbon stock. Sustainability analysis of carbon sequestration potential was done using ]0–10], ]10–40], and ]40–110 cm] diameter class as long term, medium term, and short term, respectively. The balance between marketable carbon value and the trade-off from tree conservation of three major crops was also analyzed. The results revealed 24.71 ± 5.84 tCO2 ha−1, 28.35 ± 5.84 tCO2 ha−1, and 33.86 ± 5.84 tCO2 ha−1 in Ouahigouya, Sapouy, and Bouroum-Bouroum at p < 0.1 respectively. Long- and short-term carbon sequestration potential was attributed to Ouahigouya with 1.82 and 68.03%, respectively. With, the medium term analysis Sapouy came first with 71.71% of total amount of carbon. The marketable carbon value was less than trade-off value resulting in keeping trees and crop production. The balance analysis revealed that carbon payment system promoted by REDD+ initiative will be profitable and compensable to smallholder farmers effort to plant and keep tree when the tCO2 ha−1 price will be around US$ 4.00. By taking into account farmers’ interests and profitability on carbon market will be the most relevant incentive method to enhance carbon stock in agroforestry parkland.     

Overview and modeling of mechanical and thermomechanical impact of underground coal gasification exploitation

From an economic point of view Underground Coal Gasification (UCG) is a promising technology that can be used to reach coal resources that are difficult or expensive to by conventional mining methods. Furthermore, the process addresses safety concerns, by avoiding the presence of workers underground. An optimal UCG process requires the integration of various scientific fields (chemistry, geochemistry, geomechanics) and the demonstration of limited of environmental impacts. This paper focuses on the mechanical component of the UCG operation and its impact on the surrounding environment in terms of stability and land subsidence. The mechanical components are also considered. Underground mining by coal combustion UCG challenges include the mechanical behavior of the site and of stability of the overburden rock layers. By studying the underground reactor, its inlet and outlet, we confirm the key role played by mechanical damage and thermo-mechanical phenomena are identified. Deformation or collapse above the cavity may cause a collapse in the overlying layers or subsidence at the surface level. These phenomena are highly dependent on the thermoporomechanical behavior of the rock surrounding the cavity (the host rocks). Unlike conventional methods, the UCG technology introduces an additional variable into the physical problem: the high temperatures, which evolve with time and space. In this framework, we performed numerical analyses of the coal site that could be exploited using this method. The numerical results presented in this paper are derived from models based on different assumptions describing a raw geological background. Several 3D (3 dimensional) and 2D (2 dimensional, plane) nonlinear finite element modelings are performed based on two methods. The first assumes a rock medium as a perfect thermo-elastoplastic continuum. In the second, in order to simulate large space scale crack propagation explicitly, we develop a method based upon finite element deactivation. This method is built on a finite element mesh refinement and uses Mohr-Coulomb failure criterion. Based on the analysis of the numerical results, we can highlight two main factors influencing the behavior and the mechanical stability of the overburden, and consequently the UCG process evolution. The first is the size of the cavity. This geometrical parameter, which is common to all types of coal exploitation, is best controlled using the classic exploitation method. We show that in the case of UCG, the shape of the cavity and its evolution over time can be modified considerably by the thermomechanical behavior of the host rocks. The second is the presence of a heat source whose location and intensity evolve over time. Even if thermal diffusivity of the rock is low and only a small distance from the coal reactor is thermally affected, we show that the induced mechanical changes extend significantly in the overburden, and that subsidence can therefore be estimated at the surface. We conclude the integration of the mechanical analysis into a risk analysis process mechanical analysis can be integrated in a thorough risk analysis.