Watercourse maintenance: a look at the plants and hydrology of a case study on the Tiber River

In order to prevent damage caused by extreme hydrological events in a river basin, it is of the utmost importance that the surrounding territory and watercourses of the river are kept clear and well maintained. Although this is universally recognised as a valid concept which should be put into operation, numerous practical problems arise, mainly linked to areas to be found along many of these rivers, such as river parks and sites of community interest, which are often protected. This situation gives rise to a complex debate, in which river ecology is often in direct contrast with hydrology. For this reason a study was developed in conjunction with the Province of Perugia aimed at taking a detailed, integrated look at both watercourse plants and hydrology simultaneously. The results obtained on the reaches of the Tiber River examined have shown how plant data (the fruit of three years of monitoring existing vegetation) enable us to provide an extremely detailed picture of the state and nature of the riverine vegetation, so that ways to cut and thin it out can be proposed according to the botanical and agronomic knowledge of these species. The hydrological effects of this approach were simulated using HEC-RAS calculation procedures in order to outline the effects in flood conditions. Special attention was paid to the possible phenomenon of the partial obstruction of the stream connected with the bridges and their dimension, and with the amount of vegetation which can be expected to be uprooted by virtue of its state of conservation and its position on the river banks. These results are also useful for identifying an operational protocol, which can be helpful in contracting such maintenance work along rivers with similar characteristics to the one being studied.