A Spatial Analysis to Define Data Requirements for Hydrological and Water Quality Models in Data-Limited Regions

Abstract

The objective of the present work is a spatial analysis aimed at supporting hydrological and water quality model applications in the Canale d’Aiedda basin (Puglia, Italy), a data-limited area. The basin is part of the sensitive environmental area of Taranto that requires remediation of the soil, subsoil, surface water, and groundwater. A monitoring plan was defined to record the streamflow and water quality parameters needed for calibrating and validating models, and a database archived in a GIS environment was built, which includes climatic data, soil hydraulic parameters, groundwater data, surface water quality parameters, point-source parameters, and information on agricultural practices. Based on a one-year monitoring of activities, the average annual loads of N-NO3 and P-PO4 delivered to the Mar Piccolo amounted to about 42 t year−1, and 2 t year−1, respectively. Knowledge uncertainty in monthly load estimation was found to be up to 25% for N-NO3 and 40% for P-PO4. The contributions of point sources in terms of N-NO3 and P-PO4 were estimated at 45% and 77%, respectively. This study defines a procedure for supporting modelling activities at the basin scale for data-limited regions.

Source Apportionment of Nutrient Loads to a Mediterranean River and Potential Mitigation Measures

“…For intermittent streams, an analysis of the nutrient concentrations for the different flow conditions (high, normal, and low flow) was proposed. This analysis may provide a solid basis to evaluate the programme of measures in watersheds with intermittent streams characterised by a high variability in streamflow and nutrient concentration [8,26]. Indeed, high…”

“…For intermittent streams, an analysis of the nutrient concentrations for the different flow conditions (high, normal, and low flow) was proposed. This analysis may provide a solid basis to evaluate the programme of measures in watersheds with intermittent streams characterised by a high variability in streamflow and nutrient concentration [8,26]. Indeed, high nutrient concentrations during floods (high flow) are mainly due to agriculture as delivered to the stream with surface runoff, meanwhile the high concentrations of pollutants in low flow condition are mainly attributable to point sources.…”

“…All the steps of the methodological approach are described in details below. characterised by a high variability in streamflow and nutrient concentration [8,26]. Indeed, high nutrient concentrations during floods (high flow) are mainly due to agriculture as delivered to the stream with surface runoff, meanwhile the high concentrations of pollutants in low flow condition are mainly attributable to point sources.…”

“…The SWAT model was developed to predict the impact of land management practices on water, sediments and agricultural chemical yields in ungauged river basins [14]. The model is widely used in hydrological [8,26] and water-quality analyses at the basin scale [27,28] to assess the impact of land-use changes or climate changes on surface waters [19,29].…”

“…Whilst only measurements of streamflow and pollutant concentrations taken at the outlet can be used for estimating loads delivered to the sea on different time scales, these data are not sufficient for accurately apportioning point and diffuse pollution. Data availability is the major factor influencing the choice of methodological approach to be used for estimating non-point source pollution loads [8].…”