No abstract

No abstract

Seven catchments of diverse size in Mediterranean Europe were investigated in order to understand the main aspects of their hydrological functioning. The methods included the analysis of daily and monthly precipitation, monthly potential evapotranspiration rates, flow duration curves, rainfall-runoff relationships and catchment internal data for the smaller and more instrumented catchments. The results showed that the catchments were less "dry" than initially considered. Only one of them was really semi-arid throughout the year. All the remaining catchments showed wet seasons when precipitation exceeded potential evapotranspiration, allowing aquifer recharge, "wet" runoff generation mechanisms and relevant baseflow contribution. Nevertheless, local infiltration excess (Hortonian) overland flow was inferred during summer storms in some catchments and urban overland flow in some others. The roles of karstic groundwater, human disturbance and low winter temperatures were identified as having an important impact on the hydrological regime in some of the catchments. Key words flow regimes; runoff generation; baseflow; Mediterranean Étude des régimes et processus hydrologiques dans un ensemble de bassins versants aux eaux temporaires dans l'Europe MéditerranéenneRésumé Sept bassins versants de tailles variables, situés en Europe Méditerranéenne, ont été étudies pour appréhender les principaux aspects de leur fonctionnement hydrologique. L'analyse est conduite sur la base de données de précipitations mensuelle et journalière, d'évapotranspiration potentielle mensuelle, de courbes de débits classés, de coefficients d'écoulement et, pour les bassins les plus petits et les plus instrumentés, de données internes aux bassins. Les résultats montrent que les bassins versants considérés sont moins "arides" que prévu. Seul l'un d'entre eux est vraiment semi-aride toute l'année. Les autres bassins présentent des saisons humides, avec des précipitations qui dépassent l'évapotranspiration potentielle, permettant la recharge des nappes, l'apparition de processus de génération de l'écoulement typiques de zones "humides" et une contribution significative du débit de base. Toutefois, des phénomènes de ruissellement liés, localement, au dépassement de la capacité d'infiltration (processus Hortonien) sont observés durant les événements orageux estivaux sur quelques uns des bassins et des phénomènes de ruissellement urbain sur quelques autres. Les rôles des aquifères karstiques, des perturbations anthropiques et des faibles températures hivernales ont été identifiés comme ayant un impact important sur le régime hydrologique de certains des bassins versants.Mots clefs régimes hydrologiques; génération de l'écoulement; débit de base; Méditerranée

The objective of this work is to demonstrate that some weaknesses of the onsite packaged WWTP associated with high operational costs and energy inefficiency could be overcome by improved management. The research methodology consists of series of batch studies with sludge from municipal or onsite WWTP, which simulate different working regimes of the onsite WWTPs – daily operation, toilet flushing and dishwasher machine. A simple classical tool, Oxygen Uptake Rate (OUR) is used to prove the hypothesis that regardless the specificity of the onsite WWTPs, namely the irregularity of the flow and load, three parameters follow similar increasing and decreasing trends – inflow rate, inflow pollution load and oxygen demand in the reactor. The literature review has not shown research publication about applicability of (OUR) for management of onsite WWTPs, but has shown experience and knowledge with municipal WWTPs, which were utilized in our study. The results prove that when there is no wastewater generation in the household, the (OUR) in the reactor is very low, 0.0007 to 0.0015 mg/l.s, thus do not require high oxygen supply. However, when wastewater flushes into the onsite WWTP, the oxygen demand increases rapidly and (OUR) reaches the range of 0.0040 to 0.0063 mg/l.s depending on the type and the quantity of the incoming substrate (pollution load). These results, if verified in filed experiments will enable optimization of the energy use during onsite WWTP operation.  The suggestion is that the oxygen supply in the reactor should be adjusted according to the demand, respectively proportional to the inflow rate. In addition to the benefit of saving energy, the comprehensive sensors for dissolved oxygen monitoring, which require qualified maintenance could be avoided and replaced by simple sensors for level, which are anyway part of the equipment of most of the onsite packaged WWTP.

No abstract