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The strategy is organized to preserve the advantages of fuzzy induction-based learning and of 
connectionist techniques, while avoiding the disadvantages these present when used as monostrategy 
learning mechanisms. 
Fuzzy logic representation (Zadeh. 1981) and fuzzy learning (Binaghi, 1992) allow to represent 
uncertain and intrinsically vague knowledge in an explicit and documentable form, close to the mental 
representation of experts. 
The ability to learn in an uncertain environment from sample case data is enhanced by incorporating a 
neural technique which applies certain biowledge transmutations (Michalski, 1994) to perform a 
refinement of the existing, rough knowledge. 
The experimental study has been conducted on a rice area of the Po Basin in Northern Italy where the 
impact of agro-technology on the environment is pronounced. 
Aspects involved in the applicative domain concerning the flooded rice crop are: phenological cycles: 
water/soil interaction: agronomical practices, including soil obstruction: the distribution of herbicides and 
fertiliser distribution, depending on the rice cultivar cycles (Gomarasca. 1994). 
A vulnerability map has been produced and the qualitative and quantitative results demonstrate the 
adequacy of the proposed methodology. 
2.0 STUDY AREA 
In the western part of the alluvial plain of the Po Basin, rice is extensively cultivated in a large zone 
(5.380 Km-) along a ideal line from Turin to Milan, north of the Po River (Fig. 1). More then 95% of rice 
harvested in the whole of Italy is produced in this area. A sub-basin, called West Sesia rice-area, is 
located into this zone. It is bordered by rivers: the Dora Baltea to the west, the Po to the south, the Sesia 
to the east and the Cavour canal to the northwest. 
Our attention focused in particular on a subimage (512 x 512 pixel) where the density of rice 
cultivation is very high. .In this part of the Sesia basin, the altitude decreases constantly from northwest 
to southeast, sloping down 190 m a.s.l. to about 100 m a.s.l. A typically uniform alluvial plain, it is 
composed of old and recent fluvial and fluvio-glacial deposits. 
The sub-superface geological horizon is a gravel complex constituted by a mixture of gravel and 
sands. This is the upper productive aquifer with a very high permeability. The lower geo-lithological 
complex is more varied with sand and gravel layers and some fine-grained layers, such as silt and clay of 
varying thickness. This means that it also has an extremely varied permeability. 
The water-bearing level follows the topographic trend: it reaches the deepest level, of about 15 m u.g.l. 
in the northwest, while in the southeast it is less than 4/5 m u.g.l.. The general flow of the underground 
water f is northwest-southeast toward the Po and Sesia River. Superficial drainage is controlled by the 
hydrography. The two main contributions to the water bearing level are the runoff from the hilly area near 
the mountains in the northwest, and the irrigation canals. 
The soil obstruction of rice cultures reduces the total permeability between the fields and the water 
bearinglevel.