| Title | Testing potential mitigation measures to reduce nutrient loads to a temporary river |
| Abstract | To achieve and maintain the good ecological status of surface waters, each EU Member State is
expected to invest economic resources in a programme of measures. To do this, a preliminary
analysis to quantify the anthropogenic pressures and their impacts on surface waters is necessary
to prioritise the measures to be undertaken.
The objectives of this work were to: (i) quantify the nutrient loads from point and diffuse pollution
to the Rio Mannu stream identifying the critical time in terms of water quality, and (ii) simulate
some mitigation measures for reducing the nutrient loads being delivered to the wetland. Two
"measures" were tested to mitigate nutrient pollution in high flow and low flow conditions: (1) the
use of treated wastewater from urban wastewater treatment plants (WWTPs) for the irrigation of
cultivated olive trees and a (2) reduction in fertiliser usage rates (20%).
Results showed that under high flow conditions, NO3
-N and TP loads accounted for 89% and 99%
of the total load, respectively. The low flow contribution to the total load was very low, with NO3
-N
and TP accounting for 2.8% and 0.7%, respectively. However, the natural hydrological regime in
the study area is intermittent, and low flow represents a critical condition for the water quality due
to the high concentrations of TP and NO3
-N from WWTP discharge. Results indicated that
agriculture is the main source of NO3
-N in the surface waters. The point sources made a minor
contribution, in terms of nutrient load to the surface waters, but they constitute a relevant
hydrological pressure for the Rio Mannu, producing a shift from an intermittent hydrological
regime (natural conditions) towards a perennial regime. The measures are effective to reduce
nutrient loads in surface waters at the outlet for all hydrological conditions. Under high flow
conditions, the reduction was 9% and 12% for NO3
-N and TP loads, respectively. The reduction
increased under normal and low flow conditions (75% and 83% for NO3
-N and TP loads,
respectively).
Based on this study, it is evident that a "programme of measures" for improving the current status
of surface waters must be oriented towards reducing nutrient loads, both under high and low flow
conditions. The results show that a 20% reduction in fertiliser usage on the main crops in this area,
and the reuse of wastewater from selected WWTPs, would result in a significant reduction in the
nutrient loads delivered to the wetland, although this reduction is not large enough, and
supplementary measures would be required |
| Source | EGU General Assembly 2022, Vienna, 23-27 April 2022 |
| Keywords | mitigation measuresmodellingintermittent river |
| Year | 2022 |
| Type | Abstract in atti di convegno |
| Authors | De Girolamo A.M., Lo Porto A. |
| Text | 477542 2022 mitigation measures modelling intermittent river Testing potential mitigation measures to reduce nutrient loads to a temporary river De Girolamo A.M., Lo Porto A. IRSA CNR, IRSA CNR Published version https //doi.org/10.5194/egusphere egu22 11352 EGU General Assembly 2022 Vienna 23 27 April 2022 Internazionale Contributo To achieve and maintain the good ecological status of surface waters, each EU Member State is expected to invest economic resources in a programme of measures. To do this, a preliminary analysis to quantify the anthropogenic pressures and their impacts on surface waters is necessary to prioritise the measures to be undertaken. The objectives of this work were to i quantify the nutrient loads from point and diffuse pollution to the Rio Mannu stream identifying the critical time in terms of water quality, and ii simulate some mitigation measures for reducing the nutrient loads being delivered to the wetland. Two measures were tested to mitigate nutrient pollution in high flow and low flow conditions 1 the use of treated wastewater from urban wastewater treatment plants WWTPs for the irrigation of cultivated olive trees and a 2 reduction in fertiliser usage rates 20% . Results showed that under high flow conditions, NO3 N and TP loads accounted for 89% and 99% of the total load, respectively. The low flow contribution to the total load was very low, with NO3 N and TP accounting for 2.8% and 0.7%, respectively. However, the natural hydrological regime in the study area is intermittent, and low flow represents a critical condition for the water quality due to the high concentrations of TP and NO3 N from WWTP discharge. Results indicated that agriculture is the main source of NO3 N in the surface waters. The point sources made a minor contribution, in terms of nutrient load to the surface waters, but they constitute a relevant hydrological pressure for the Rio Mannu, producing a shift from an intermittent hydrological regime natural conditions towards a perennial regime. The measures are effective to reduce nutrient loads in surface waters at the outlet for all hydrological conditions. Under high flow conditions, the reduction was 9% and 12% for NO3 N and TP loads, respectively. The reduction increased under normal and low flow conditions 75% and 83% for NO3 N and TP loads, respectively . Based on this study, it is evident that a programme of measures for improving the current status of surface waters must be oriented towards reducing nutrient loads, both under high and low flow conditions. The results show that a 20% reduction in fertiliser usage on the main crops in this area, and the reuse of wastewater from selected WWTPs, would result in a significant reduction in the nutrient loads delivered to the wetland, although this reduction is not large enough, and supplementary measures would be required Abstract in atti di convegno antonio.loporto LO PORTO ANTONIO annamaria.degirolamo DE GIROLAMO ANNA MARIA |
