Droughts, the case study of the Po river basin

Posted on

Droughts are a natural phenomenon related to a below average water availability, perhaps lasting a few weeks, or even months, over a region, in terms of rainfall, discharge or groundwater, and they can occur in any region of the planet. They can be classified in hydrological, if they involve periods of below normal flow and depleted reservoir storage; meteorological, relatively, to below normal precipitation ; agricultural, if the soil moisture is not sufficient to support crop growth; socio-economical, when the low water supply affects society’s productive and consumptive activities.

In a new study recently published on Water Resources Research a team of scientists (among them, the CMCC researcher Renata Vezzoli from ISC Division) focused the attention on hydrological droughts, while using the case study of the Po river basin as illustration. 
They assessed and analyzed droughts episodes by means of two variables, drought intensity and duration. Moreover, they introduced a new concept, i.e. Dynamic Return Period, that could be useful to monitor the temporal evolution of a drought event while performing real time assessment.
Results highlighted that the method may help to better plan effective mitigation strategies in due time and cope with the consequences of low flow.

The abstract of the paper:
Droughts, like floods, are extreme expressions of the river flow dynamics. Here, droughts are intended as episodes during which the streamflow is below a given threshold, and are described as multivariate events characterized by two variables: average intensity and duration. In this work, we introduce the new concept of Dynamic Return Period, formulated using the theory of Copulas, and calculated via a Survival Kendall’s approach. We show how it can be used (i) to monitor the temporal evolution of a drought event, and (ii) to perform real time assessment. In addition, a randomization strategy is introduced, in order to get rid of repeated measurements, which may adversely affect the statistical analysis of the available data, as well as the calculation of the return periods of interest: a practical example is shown, involving the fit of the drought duration distribution. The case study of the Po river basin (Northern Italy) is used as an illustration.

Read the integral version of the paper:

De Michele C., Salvadori G., Vezzoli R., Pecora S.
Multivariate assessment of droughts: Frequency analysis and dynamic return period

2013, Water Resources Research, Volume 49, Issue 10, pages 6985–6994, DOI: 10.1002/wrcr.20551

Start typing and press Enter to search

Shopping Cart