**1. Introduction**

Actual agricultural systems are based on intensive farming techniques that require deep plowing, and large usage of nitrogen (N), phosphorus (P), herbicides, pesticides, energy inputs, and land [1]. Leaching losses of sediments, nutrients, and chemicals from agricultural fields can lead to eutrophication of water and soil, deterioration of agroecological systems, and loss of ecosystem services. Agricultural production potential and the capacity to provide other ecosystem services in the future are both reduced as a result of pressures on agricultural systems and natural resources [2], endangering the main soil functions (such as filtering and serving as biological habitats) and their preservation [3]. Agricultural systems face several pressing challenges in resolving the apparent conflict between human needs and resource sustainability [4].

The managemen<sup>t</sup> of the environment is a significant problem in highly managed Mediterranean river basins. Many solutions have been put out for addressing management issues and local environmental effects on agroecological systems. The use of ecohydrological modelling for ex-ante quantification of nonpoint source pollution and soil erosion in agroecosystems is a useful approach for implementing sustainable agricultural systems [5]. Many studies have found that eco-hydrological models are effective in simulating the intricate interactions of water, nutrients (N and P), contaminants, and vegetation systems in both natural and agricultural ecosystems.

These models can help researchers and practitioners to better understand and manage these ecosystems, leading to improved crop yields and reduced environmental impact.

**Citation:** Pulighe, G.; Lupia, F. Eco-Hydrological Modelling of a Highly Managed Mediterranean Basin Using the SWAT+ Model: A Preliminary Approach. *Environ. Sci. Proc.* **2023**, *25*, 24. https://doi.org/ 10.3390/ECWS-7-14179

Academic Editor: Silvia Kohnova

Published: 14 March 2023

**Copyright:** © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

Additionally, eco-hydrological models can be used to predict the effects of climate change and other disturbances on agricultural ecosystems, allowing for more effective planning and adaptation. One of the most frequently utilized models is the Soil Water Assessment Tool (SWAT) [6]. Examples include streamflow and nutrient loadings [7], modelling of soil erosion [8], best managemen<sup>t</sup> practices for reducing fertilizer application [9], and climate change studies [10].

This paper focuses on the application of the SWAT+ model in a Mediterranean river basin to evaluate the influence of anthropogenic managemen<sup>t</sup> on water balance components, nutrients, and sediment loads. The model employs a high-precision land use map produced from the administrative geodata of the Italian Integrated Administration and Control System (IACS)/Land Parcel Identification System (LPIS) used for monitoring the Common Agricultural Policy (CAP) subsidies. High-resolution land use data provide precise information on landscape patterns and allow us to better represent the hydrological cycle. The model performances were assessed by comparing simulated and observed streamflow data and calculating a goodness-of-fit objective function. The preliminary findings show that the model reproduced the water balance in the watershed well. Future work will be oriented to analyze the effects of alternative managemen<sup>t</sup> practices on water quality, sediment loads, and soil erosion.

### **2. Materials and Methods**

### *2.1. Study Area*

This study was carried out in the Cervaro river basin, which is located in the Apulia Region (southern Italy) between 41◦07–41◦32 N latitude and 15◦06–15◦54 W longitude (Figure 1). The Cervaro basin has an area of 841 km<sup>2</sup> and ranges in elevation from 0 to 1100 m on the southern side of the Daunia Mountains. The river system consists of the main river course and various major and secondary-order tributaries. The climatic regime is Mediterranean with a bimodal pattern of precipitation distribution with rainy winters and hot summers.

**Figure 1.** Location of the study area.

*2.2.*

SWAT is a semi-distributed eco-hydrological model that segments a watershed and its sub-watersheds into homogenous geographical units known as Hydrologic Response Units (HRUs), each of which have a distinct combination of land use, soil, and slope [6]. The HRUs are used to determine the soil–water balance. HRUs represent the minimum computational unit within which the soil–water balance is determined. In this study, we used the new restructured SWAT+ model that is more efficient and flexible in terms of model construction and configuration.

### *2.3. Dataset and Model Setup*

The SWAT+ model requires the following geospatial data for implementation (Table 1): land use/cover data, soil data, Digital Elevation Model (DEM), streamflow data, and climate data. In the first step, the DEM was used to delineate the basin and create sub-basin boundaries, while in the second step HRUs were created in conjunction with land use and soil data. In the third step, climate data for the period 1990–2019 were used to set up and run the model as the baseline scenario.

For land use data, we specifically developed a detailed land use map for the study area with 57 thematic classes from the IACS/Land Parcel Identification System (LPIS) conflation [11,12]. More than 70% of the area is devoted to agricultural uses. The SWAT+ model (rev. 60.5.4 – SWAT+ Editor 2.1) was implemented using a QGIS interface and run at daily timesteps from 1 January 1990 to 31 December 2019 considering a 4-year warm-up. The study area was discretized into 7345 HRUs. The Penman–Monteith method was used to calculate potential evapotranspiration.

**Table 1.** Data sources used to implement the SWAT+ model.

