Improved Modelling of Soil Loss in El Badalah Basin: Comparing the Performance of the Universal Soil Loss Equation, Revised Universal Soil Loss Equation and Modified Universal Soil Loss Equation Models by Using the Magnetic and Gravimetric Prospection Outcomes

Water erosion is a natural fact in the cycle of shaping the earth’s landforms and the most evident form of land degradation on a planetary scale (Roose & De Noni, 2004; Dautrebande & Sohier, 2006; Toumi et al., 2013; Azaiez, 2020a). Its effects have largely affected the rural landscape. Although it is the result of an ancient and primeval climatic and tectonic forcing, man’s footprint in its intensification remains a reality. A real awareness of this problem on the part of scientists is reflected in the many studies on understanding the risks. Experiments have been carried out, equations and models have been developed with the aim of preserving the soil. The watershed of wadi El Badalah, the subject of this study, is not excluded from this risk. The present research is a new comparative contribution to the quantification of soil loss based on four empirical models (Universal Soil Loss Equation USLE, Revised Universal Soil Loss Equation RUSLE, Modified Universal Soil Loss Equation MUSLE and the adjusted model). The main objective of this research project is to test several empirical models of quantification of soil loss, extensively tested on a global scale, to discuss the potential of each model in order to choose the most appropriate for the El Badalah basin. The method is based on geotechnical and geophysical investigations. It consists of determining the anomalies of the subsoil based on the difference in density and the resistivity of the heterogeneous constituents of the subsoil. This is in order to look for sectors potentially favorable to infiltration at the expense of runoff.

A NUMERICAL SIMULATION OF THE GEOSTROPHIC ADJUSTMENT PROCESS

In this paper,a numerical simulation of the geostrophic adjustment process with C-grid network is illustrated.A difference scheme which has the energy and potential vorticity conserving relation consistent with the differential equations is given,and the effect of some time difference schemes on dispersion of the gravity-inertia wave is discussed.An improved forward-backward time integration scheme is proposed for keeping the computational stability.The effect of various boundary conditions for a finite region model On the gravity-inertia wave is shown by some calculated results.

Transcriptome sequencing and annotation of the halophytic microalga Dunaliella salina

The unicellular green alga Dunaliella salina is well adapted to salt stress and contains compounds（including β-carotene and vitamins） with potential commercial value.A large transcriptome database of D.salina during the adjustment, exponential and stationary growth phases was generated using a high throughput sequencing platform.We characterized the metabolic processes in D.salina with a focus on valuable metabolites, with the aim of manipulating D.salina to achieve greater economic value in large-scale production through a bioengineering strategy.Gene expression profiles under salt stress verified using quantitative polymerase chain reaction（qPCR） implied that salt can regulate the expression of key genes.This study generated a substantial fraction of D.salina transcriptional sequences for the entire growth cycle, providing a basis for the discovery of novel genes.This first full-scale transcriptome study of D.salina establishes a foundation for further comparative genomic studies.

THE DYNAMICAL BASIS OF GEOSTROPHIC ADJUSTMENT MOTIONS IN TROPICS

Some dynamic constrains in the process of the tropical baroclinic geostrophic adjustment are discussed.The dispersion equation of three-dimensional inertia-gravitational wave and the equation of temporal conservation of potential vorticity are given,without considering the gradient of planetary potential vorticity.It indicates that the motions will be horizontal,meaning that Taylor-Proudman theorem is still right for tropics.At the same time,the semi-geostrophic balance is easier to appear in the tropical belt.Therefore the motions are generally horizontal and non-divergent,but still are stratified after the geostrophic balance establishes.