Modeling Hydrological Responses to Land Use Change in Sejnane Watershed, Northern Tunisia

Abstract

Land use change is a crucial driving factor in hydrological processes. Understanding its long-term dynamics is essential for sustainable water resources management. This study sought to quantify and analyze land use change between 1985 and 2021 and its impacts on the hydrology of the Sejnane watershed, northern Tunisia. Remote sensing and a SWAT model using the SUFI-2 algorithm to identify the most sensitive parameters were used to achieve this objective. Land use maps were developed for 1985, 2001 and 2021. For the last 37 years, the watershed experienced a slight decrease in forest, scrubland and forage crops, a significant reduction in grassland, and a conspicuous expansion of olive trees and vegetable crops. Given the scarcity of observed discharge data, a SWAT model was calibrated for the period 1997–2010 and validated for 2011–2019. Model performance was good for both calibration (NSE = 0.78, PBIAS = −6.6 and R2 = 0.85) and validation (NSE = 0.70, PBIAS = −29.2 and R2 = 0.81). Changes in land use strongly affected the water balance components. Surface runoff and percolation were the most influenced, showing an increase in runoff and a decrease in percolation by 15.5% and 13.8%, respectively. The results revealed that the construction of the Sejnane dam, the extension of irrigated perimeters and olive tree plantations were the major contributors to changes in hydrology.

Soil Erosion in a Changing Environment over 40 Years in the Merguellil Catchment Area of Central Tunisia

“…Numerous investigations have been conducted in Tunisia concerning changes in Land Use and Land Cover (LULC) [21,42] as well as sediment yield [2]. Worldwide, there is limited research specifically dedicated to quantifying the impact of LULC changes on soil erosion and sediment yield [50][51][52][53].…”

“…Recognizing the consequences of changes in LULC on soil erosion patterns, sediment transportation, and the delivery of ecosystem services is of the highest importance when crafting holistic approaches for successful watershed management. Numerous investigations have been carried out to evaluate the influence of LULC changes [19][20][21] on soil erosion and sediment yield [22,23]. These investigations provide valuable insights into the relationship between land use alterations and erosion processes.…”