Studio preliminare sul rischio di desertificazione nel territorio carsico di Lecce
Abstract
It
L'eccessivo sfruttamento degli acquiferi carsici del Salento ha prodotto, da tempo,l'insorgere del fenomeno della salsificazione delle acque di falda. L'uso di acque salmastre per l'irrigazione delle colture può determinare, nel lungo termine, la perdita del potenziale biologico dei suoli. Pertanto, in uno con l’esigenza di utilizzare acqua anche da altre fonti di approvvigionamento, si pone, inderogabile, la necessità di definire un modello di circolazione idrica negli acquiferi carsici al fine di valutare la quantità di risorsa emungibile senza dar luogo a significativi effetti di salsificazione. In questa nota si descrivono le basi fisico - matematiche del modello proposto (relativo al territorio di Lecce) e la metodologia approntata per la definizione dei relativi parametri.
En
Groundwater salinisation as a result of an overexploitation leads, in the long term, to the loss of biological potential of soils (desertification phenomenon). Together with the utilization of other sources, the definition of a model for the prevision of groundwater flow seems mandatory in order to evaluate the sustainable amount of groundwater resource which can be exploited. The note illustrates the physico–mathematical basis of such a model (based on the hydrogeological features of the Lecce karst zone) and the methodology setup for the definition of the related parameters. The model needs to carry out the following phases: choice of a conceptual reference scheme; definition of the representative equations of the phenomenon; direct measurement of some physical quantities; determination of the parameters under discussion; validation and refinement of the model; forecasting according to possible or predictable scenarios. The problem of definition and forecast of solute transport in the aquifer can be faced through the adoption of an hydraulically equivalent medium submitted to a process of filtering with transport of solute, whose fieldvarying are the hydraulic pressure and salt concentration. The equivalence is obtained associating to the fictitious porous medium the hydraulic conductivity and the dispersion tensor produced by means of the hydraulic and geometric characteristics of the dominant system of fractures and karst cavities. The resolution of the problem needs a couple of differential equations of the second order or of numerical solutions. As regards the present management of the groundwater resource of the Salento, due to the state of knowledge and the level of available tools, the authorities should pay greater attention to the negative impact of the new pumping projects.
L'eccessivo sfruttamento degli acquiferi carsici del Salento ha prodotto, da tempo,l'insorgere del fenomeno della salsificazione delle acque di falda. L'uso di acque salmastre per l'irrigazione delle colture può determinare, nel lungo termine, la perdita del potenziale biologico dei suoli. Pertanto, in uno con l’esigenza di utilizzare acqua anche da altre fonti di approvvigionamento, si pone, inderogabile, la necessità di definire un modello di circolazione idrica negli acquiferi carsici al fine di valutare la quantità di risorsa emungibile senza dar luogo a significativi effetti di salsificazione. In questa nota si descrivono le basi fisico - matematiche del modello proposto (relativo al territorio di Lecce) e la metodologia approntata per la definizione dei relativi parametri.
En
Groundwater salinisation as a result of an overexploitation leads, in the long term, to the loss of biological potential of soils (desertification phenomenon). Together with the utilization of other sources, the definition of a model for the prevision of groundwater flow seems mandatory in order to evaluate the sustainable amount of groundwater resource which can be exploited. The note illustrates the physico–mathematical basis of such a model (based on the hydrogeological features of the Lecce karst zone) and the methodology setup for the definition of the related parameters. The model needs to carry out the following phases: choice of a conceptual reference scheme; definition of the representative equations of the phenomenon; direct measurement of some physical quantities; determination of the parameters under discussion; validation and refinement of the model; forecasting according to possible or predictable scenarios. The problem of definition and forecast of solute transport in the aquifer can be faced through the adoption of an hydraulically equivalent medium submitted to a process of filtering with transport of solute, whose fieldvarying are the hydraulic pressure and salt concentration. The equivalence is obtained associating to the fictitious porous medium the hydraulic conductivity and the dispersion tensor produced by means of the hydraulic and geometric characteristics of the dominant system of fractures and karst cavities. The resolution of the problem needs a couple of differential equations of the second order or of numerical solutions. As regards the present management of the groundwater resource of the Salento, due to the state of knowledge and the level of available tools, the authorities should pay greater attention to the negative impact of the new pumping projects.
DOI Code:
10.1285/i15910725v26supp135
Full Text: PDF
