Ossama.M.M. Abdelwahab

{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.}

{This study aims to evaluate the suitability of the Soil and Water Assessment Tool model in simulating runoff and sediment loss in the Carapelle (SE Italy), a typical Mediterranean watershed, where continuous measurements of streamflow and sediment concentration were collected over a 5-year period, on a half-hour timescale, processed on a daily timescale. After sensitivity analysis, the model was calibrated and validated for runoff and sediment. Statistics show generally satisfactory efficiency. To further improve sediment simulation performance, we used a seasonal calibration scheme, in which data recorded in the dry and wet seasons were used to calibrate sediments separately, on a seasonal basis. We also tested the model's capability in identifying the major sediment source zones and river segments where there is sediment deposition. On the basin scale, the average water yield (186mm) corresponds to 27% of the total rainfall (686mm), and average annual sediment load was estimated to be 6.8tha(-1)year(-1). On the subbasin scale, a gradient of sediment yield was found that is characterised by a large difference among the upper (7 to 13tha(-1)year(-1)), central, and lower parts (<1tha(-1)year(-1)) of the study area. Conversely, deposition in channel flow has its highest values in the central part of the watershed, where there is an alluvial plain. Winter wheat and olive land use are the major source areas, in terms of sediment. This study confirms that the Mediterranean watershed is a fragile ecosystem, and measures are needed to mitigate soil depletion.}

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Abstract The aim of this study is to model potential changes in land use and evaluate their effects on sediment load in a Mediterranean watershed, the Carapelle, in Southern Italy. For this purpose, a set of Landsat Thematic Mapper (TM) images were processed to generate three different land use maps for 1987, 2002, and 2011. The images were corrected for geometric distortion and atmospheric interference before performing an unsupervised classification and decision expert system post classification. The land use maps for 1987 and 2002, derived from the Landsat \{TM\} processing, were analyzed using a Land Change Modeler (LCM) module to identify transitions from the first land cover type to the second. The transitions were modeled using a multi-layer perceptron (MLP) neural network to create transition potential maps, which provide the controls for subsequent dynamic land use change predictions. The model produced a predicted land use map for 2011 using Markov Chain analysis, which was validated with the actual 2011 land use map. Consequently, a land use scenario (S1) for 2035 and 2050 was predicted, taking into account the current constraints and management options. \{LCM\} was further used to define two additional scenarios (S2 and S3) both for 2035 and 2050 based on different land management options. Finally, the Annual Agricultural Non-Point Source Pollution Model (AnnAGNPS) was used to estimate the effect of the predicted land use changes on sediment load after model calibration, using a five-year dataset registered at the Ordona monitoring station. The land use change analysis revealed low transformations from 1987 to 2011. Equally, land use changes were low for the base scenario (S1) so moderate variations in sediment load were estimated. The changes in land use were more significant for the additional scenarios (S2 and S3) and consequently the model estimations underwent major variations, with a significant reduction of soil erosion. The associated utilization of land use change analysis and AnnAGNPS modeling demonstrates how land use management options can be adopted to reduce potential watershed sediment load.