ABSTRACT
Sometimes, the design and construction of works for a canal take place under especially difficult circumstances. Generally, the problem comes from its location in complicated ground structure, among which we can cite expansive clay, gypsum-bearing soils and loess. However, on other occasions the conditioning factors are due to the actual canal operation itself, as in the case in which an existing canal has to be lined, but for service requirements it is not possible to empty it and the lining works have to be carried out with water still circulating. When the problem is caused by the design of a canal on complicated
ground, the adopted solution always includes an attempt to vary its course in order to locate more favourable land, but since this is almost always impossible, it then becomes necessary to isolate the canal itself from the surrounding adverse environment. When dealing with specific problems imposed by operation of the canal it is not possible to provide any hard and fast rules, instead, an attempt must be made to take advantage of whatever favourable circumstances there may be.
