Relationship between the yearly maxima of peak and daily discharge for some basins in Tuscany

ABSTRACT

The paper deals with the estimation of the probability distribution of the yearly maximum of the peak discharge Q by means of the distribution of the maximum of the daily discharge q and the distribution of the ratio R = Q/q. The study was carried out for some catchments in Tuscany, analysing the dependence of the parameters of R on the geomorphic catchment parameters. The values of the discharge Q, relevant to an assigned return period, obtained by the methods given herein agree rather well (the error is about 20%) with those directly obtained from the observed values of Q.     

Integration of surface water with groundwater resources aided by numerical modelling

ABSTRACT

The possibility was studied of a gradual extension of the irrigable area of the Tarlac Irrigation System, located in the alluvial plain of Luzon Island (Philippines). The extension would be made by integrating groundwater with surface water supplied from a reservoir already designed. Aquifer exploitation was studied adopting the criterion that groundwater is a very expensive resource to be turned to only in severe drought years. The objectives of the study were twofold: (a) planning the distribution of the wells (to be drilled during the various stages of the irrigation system development) so as to minimize the pumping cost; (b) establishing a policy for the well management in conjunction with the reservoir operation. Different schemes of the combined system management were analysed on the basis of the climatic and hydrological regime over the period 1950–1972. For this period the monthly water requirements for the different crops and the monthly values of aquifer recharge were computed. The economic analyses were performed using present prices of agricultural products and power together with several different hypotheses about future prices. A finite element model of the semiconfined aquifer was postulated and calibrated; the importance of the return flow from irrigation was also tested. Simulations of exploitation schemes provided a detailed forecast of the aquifer response to the irrigation demands.     

Blueschist and Eclogite transformations in Fe-Ti Gabbros: A Case from the Western Alps Ophiolites

The study of the alpine metamorphism of three suites of Fe-Timetagabbros occurring in the western Alps ophiolites has showna set of reactions governed by T, P, X_H2O, and diffusion. T-Pestimates point to 350?50?C at a minimum of 9–10 kb forthe Queyras blueschist rocks and to 450–500 ?C at a minimumof 12–13 kb for the Lanzo and Rocciavr` eclogitized rocks.These variations are the result of different T-P-time trajectoriesduring subduction/obduction events of alpine age. In the Fe-Timetagabbros, little-deformed volumes showing a crystallizationhistory controlled by local equilibrium are bounded by mylonites.Water-poor and water-rich volumes alternate during eclogitizationof the Rocciavr? suite. The persistence in the little-deformedrocks of prealpine metastable relics, of corona structures andof chemical gradients, demonstrates that a complete high pressureequilibration is inhibited by slow reaction kinetics and slowdiffusion. Only in the mylonites has the catalytic effect ofdeformation favoured an approach to bulk-rock metamorphic equilibration.In the eclogitized coronitic rocks the apparent O₂, releasefrom the alteration of the magmatic opaques plays an importantrole in reaction rates; increasing extent of eclogitizationmay be enhanced either by the release of free O₂ from the rocks,or by a process in which new H₂O formed by the combination ofoxygen with hydrogen introduced into the system.