Seydou Traore

A mixture neural methodology for computing rice consumptive water requirements in Fada N’Gourma Region, Eastern Burkina Faso

Crop consumptive water requirement (Crop-ET) is a key variable for developing management plans to optimize the efficiency of water use for crop production particularly in semiarid zone. In Burkina Faso, the unfavorable climatic conditions characterized by the low and unevenly distribution of rainfall have pushed water resources management to the forefront of the crop production issue. Crop-ET is extremely required in rainwater effective management for mitigating the impact of water deficit on the crops. Basically, Crop-ET determination involves reference evapotranspiration (ETo) and crop coefficient (Kc) which required complete climatic data and specific site crop information, respectively. ETo estimation with the recommended FAO56 Penman–Monteith (PM) equation is limited in Burkina Faso due to the numerous meteorological data required which are not always available in many production sites. In such circumstances, research to compute directly Crop-ET as an alternative to the two-step approach of calculating ETo and determining site specific Kc, seems desirable. Therefore, this study aims to evaluate the performance of a mixture principal component analysis neural network (PCANN) model for computing rice Crop-ET directly from temperatures data in Fada N’Gourma region located in Eastern Burkina Faso, Africa. From the statistical results, rice Crop-ET can be successfully computed by using PCANN methodology, when only temperatures data are available in this African semiarid environment. Thus, in poor data situation, Crop-ET direct computation can be rapidly addressed through PCANN model for agricultural water management in African semiarid regions.

Predicting and managing reservoir total phosphorus by using modified grammatical evolution coupled with a macro-genetic algorithm

A model that predicts the monthly water quality for a subtropical deep reservoir was constructed based on a newly developed programming system, the incremental grammatical evolution (IGE). IGE was designed to execute Grammatical Evolution (GE) by iteratively introducing the optimal solution until convergence, and to explore complex veiled relationships between inputs and outputs when physical models cannot be defined in advance. A disadvantage of traditional GE is that it tends to select the most significant input variables and may become trapped in a local optimum. The IGE adequately manages the large input dimensionality by incrementally expanding the search depth. From three IGE runs, we extracted four significant input variables from 15 input variables, including watershed chemical loads, precipitation, inflow, and outflow, and expressed them appropriately in a sophisticated mathematical manner with accepted complexity. The IGE-derived equation yields the optimal predictive capability, especially for peak total phosphorous (TP) values, compared to traditional multilinear regression (MLR) and back-propagation neural network (BPNN) models. The sensitivity analyses reconfirm the effectiveness of the selected variables in the nonlinear mathematical equations. Although BPNN and IGE demonstrate similar performances, we preferred the latter because of its transparency in providing a formula with measurable parameters. After obtaining the IGE-derived model, a Macro-evolutionary Genetic Algorithm (MEGA) was applied to enhance searching efficiency and genetic diversity during optimization, and subsequently deduced the reduction rates of TP loads from various input sources to achieve the water quality requirement of the reservoir. This practice benefits the reservoir management by revealing the forcing functions that are manageable to prevent reservoir eutrophication.