Climate and water budget change of a Mediterranean coastal watershed, Ravenna, Italy

Abstract

It is generally difficult to quantify exactly the freshwater going in or out of the coastal watersheds along the northern Adriatic Sea because, on one hand, excess water is drained and pumped into the sea to prevent flooding but, on the other hand, water is brought onto the land from far away for irrigation. Fragmentation of water authorities makes it difficult to collect all the necessary information. Climate change and increasing salinization of the coastal aquifers make it imperative, however, to better know the quantities of freshwater involved in these small basins. The water budget of a small coastal agricultural watershed along the Adriatic Sea in Italy (The Quinto Basin near Ravenna) is presented here considering different land uses. The evaporation of open water and the evapotranspiration of wetlands, pine forests, bare soil and irrigated agriculture are calculated based on the PenmanMonteith equation and the Cropwat program. The current water budget is based on average climate data from 1989 to 2008 and drainage and irrigation data. Predictions for future evapotranspiration, net irrigation and hydrologic deficit are calculated with climate data from IPCC (The Fourth Assessment Report (AR4) 200, Climate change 2007). From the study results, the soil type may determine whether or not a crop will need more or less irrigation in the future. Regulations on land use should therefore consider which crop type can be grown on a specific soil type. Water budget analysis in scenarios A1b and A2 both show an increase of water deficits in the summer and an increase of water surplus in the winter. This is explained by the fact that a larger percentage of the rain will fall in winter and not during the growth season. The open water evaporation will decrease under future climate scenarios as a result of increased relative humidity in winter and decreased wind velocity. This may have a positive effect on the water cycle. The current irrigation is very abundant, but has beneficial effects in contrasting soil salinization and saltwater intrusion into the coastal aquifer.

Metal accumulation in an artificially recharged gravel pit lake used for drinking water supply

“…The amount of metal deposited in a single lake can be considerable (see next section) and since in some watersheds there are so many of these lakes (this study and e.g. Mollema et al, 2012Mollema et al, , 2013Peckenham et al 2009) the entrapment of the metals changes the metal budget of the watershed with consequences for the metal budget and the ecosystems further downstream and along the coast. Downstream from the DLV lake, oxygen-rich water infiltrates into the bank towards the production wells.…”

The influence of flow‐through saline gravel pit lakes on the hydrologic budget and hydrochemistry of a Mediterranean drainage basin

“…Some of the abandoned gravel pit lakes are used for recreational activities such as swimming, canoeing, fishing and boating. In the watershed between the Fiumi Uniti River and the Bevano River, the gravel pit lakes cover 684 hectares or 7% of the land surface (Mollema et al ). The three gravel pit lakes that were studied in detail are the Cavallino Lake, the EMS Lake, and the Standiano lake (Figs.…”

“…The mean annual precipitation over the period 1991–2008, averaged over four nearby weatherstations is 635 ± 116 mm. Average winter precipitation (October through March) is 292 ± 66 mm and average summer precipitation (April through September) is 343± 51 mm (Mollema et al ). The average maximum temperature is 19°C and the average minimum temperature is 8°C with July and August the warmest and December and January the coldest months of the year.…”

“…Open water evaporation from surface waters in the area was calculated by Mollema et al () using the Penman () equation described in Maidment () that describes how the available energy from the sun is used for water evaporation. The average annual open water evaporation for the period 1988–2008 is 1529 mm per year (Mollema et al ) of which 348 mm evaporates in winter (October through March) and 1181 mm in summer (April through September). Mean annual wind speed averaged over four weather stations is 1.9 ± 0.6 m/s (Mollema et al ).…”

Geothermal characterization of the coastal aquifer near Ravenna (Italy)

“…Tale risorsa, però, è sempre più compromessa dalla crescente salinizzazione dell'acquifero freatico (Antonellini et al, 2008), il che sta creando seri problemi agli ecosistemi costieri, all'agricoltura e alle pinete storiche di Ravenna. Studi recenti hanno messo in evidenza che la salinizzazione dell'acquifero è causata indirettamente dalla subsidenza che costringe le idrovore della bonifica ad un drenaggio sempre più spinto ed alla risalita di acqua salata lungo i fiumi che sfociano a mare (Antonellini et al, 2008;Giambastiani et al, 2007;Giambastiani et al, 2009;Mollema et al, 2012;Vandebohede et al, 2012). Il più recente di questi studi ha analizzato il problema dell'intrusione salina nell'acquifero ravennate con lo scopo di migliorare la gestione delle risorsa idrica, di contenere la salinizzazione dei suoli e di salvaguardare gli habitat di grande pregio naturalistico come le pinete storiche e le lagune facenti parte del "Parco Regionale del Delta del Po".…”