Does productive capital affect the order of resource exploitation?

The purpose of this paper is to show that in a general equilibrium framework it is never optimal to use high cost substitute after lower cost exhaustible resource even if it is possible to accumulate productive capital. Indeed if the high cost substitute is scarce it is always optimal to consume it simultaneously with a lower cost stock. Moreover it may be optimal to consume the high cost substitute before using a lower cost resource

Input use and capacity constraint under uncertainty: The case of irrigation

In this paper we consider a two periods model of cropping using irrigation. The farmer takes two kind of decisions, one related to the level of investment in irrigation capacity and the other one to the irrigation level in each period. In the first period, decisions are taken under uncertainty on the rainfall level which is resolved at the beginning of the second period. Assuming a CARA utility function, we show that taxing the investment may entail an increase in preventive irrigation although the investment decreases. Moreover, in the case of a logistic production function, the total water use is non monotonic with respect to the price of investment. Indeed, taxing capital may induce the farmer to increase the total level of irrigation despite that the irrigation capacity decreases. Surprisingly, the impact of an increase of water price is generally ambiguous even assuming risk neutrality

Does S. Kuznets' belief question the environmental Kuznets curves?

This paper examines the link between pollution and income. It shows how income inequality affects environmental policies and therefore pollution. The Environmental Kuznets Curve (EKC) hypothesis proposes that there is an inverted U-shape relation between environmental degradation and income per capita. This paper invalidates this common result. Indeed we find for a set of parameters a two-hump curve

Can Occupational Proficiency Diplomas (CAP and Vocational Diplomas (BEP) Still Lead to Qualified Jobs?)

Level V diplomas, such as occupational proficiency diplomas (CAP) and vocational diplomas (BEP), are less likely to lead to qualified jobs than in the past. The professional career paths of young people entering the labour market in September 1992 and in September 1998 were studied, and focused on the three years following their departure from the education system. Five different situations can be distinguished: unemployment, inactivity, non-qualified employment, qualified employment and highly qualified employment. Regardless of the year or population, movement between these situations is uncommon. Diploma holders find it easier to trade unemployment for employment and are less likely to become unemployed. For some, the diploma increases their chances of finding a highly qualified job. The diploma holders sector of activity has little bearing on these trends. In short, apprenticeships offer a better professional start than lycée in terms of qualification and job stability.School-Leavers, Skilled and Unskilled Employment, Apprentice, Vocational School, Transition Intensities

Is the irrigation water demand really convex?

We estimate the irrigation water demand for a season under uncertainty using a dynamic programming model and a crop-growth simulation model (EPIC-PHASE) linked to a CRRA utility function representing the farmer's objective function. This model is used to generate the data allowing the estimation of irrigation water demand by a nonparametric procedure. An application shows that demand functions present four main areas: for very small quantities, the demand is inelastic. In the second area, where water is no more an essential input and is not yet a risk reducing input, the demand is elastic. But, we find a third, non-intuitive, area for larger quantities where the water is a risk reducing input and the demand becomes inelastic again. In the last area the water demand is obviously elastic for important total water quantities. This result is of great importance to analyse a regulation policy

Prévisions de court terme du niveau des aquifères : le cas de la nappe de Beauce

Egalement paru dans : LEERNA Discussion papers ; 00.04.37National audienceL'objectif de cette étude est de prévoir à court terme (c'est-à-dire pour une année), à partir des modélisations classiques appliquées aux séries temporelles, le niveau d'une nappe phréatique. L'intérêt de ce travail est, dans le cadre d'une gestion durable des aquifères, de fournir au décideur public des informations précises sur l'évolution des réserves en eau. Les valeurs prédites obtenues, essentiellement à partir des seuls niveaux de nappe passés, sont relativement satisfaisantes. En effet, l'erreur maximale de prévisions est de l'ordre d'un demi pour cent