ASSESSMENT OF THE EFFECTS OF LAND USE SCENARIOS ON WATERSHED SURFACE RUNOFF USING HYDROLOGICAL MODELLING

Land use/land cover (LULC) change is a major factor affecting the hydrological response at the watershed scale. However, hydrological modelling, in its current practice, is usually carried using a single and static LULC layer for simulation runs over long periods. Eventually, this approach leads to failure in accounting for LULC spatial and temporal changes as well as non-linear impacts on simulated outputs. Besides, in the typical case of Sahelian hydrosystems, previous modelling attempts based on this approach failed at reproducing the well-known Sahelian hydrological paradox which occurred in the area during the period 1970-1990. This study aims at assessing the added value of dynamical integration of LULC changes in hydrological modelling of surface runoff in Sahelian hydrosystems. The Tougou watershed (37 km&#178;), located in Northern Burkina Faso is selected as a case study. LULC maps of the watershed are produced from 1952 to 2017 from the processing of Landsat satellite images. The SWAT (Soil & Water Assessment Tool) model, using the SCS-CN method (for surface runoff estimation), is calibrated and validated using observed runoff data collected over the period 2004-2018. The calibration/validation is carried using LULC maps of the watershed in 1999, 2009 and 2017, dynamically integrated into the model using a specific land use update module. Further, the calibrated model parameters helped in the reconstitution of surface runoff over the historical period 1952-2005 and integrating dynamically LULC maps in 1952, 1973, 1986 and 1999. The results showed that between the periods 1952-1968 (P1) and 1986-2005 (P3), the average annual rainfall decreased by 87.9 mm while paradoxically, average annual runoff increased by 1 mm. Further analysis revealed that the increase in runoff is mainly attributed to LULC changes (+647%) which offsets the effect of the decrease in rainfall (-547%). From the analysis of LULC maps, it was found that from P1 to P3 periods, the decrease in natural vegetation (CN = 67.3 &#177; 5.7) by 40%, replaced by bare and degraded soils (CN = 83.8 &#177; 2.5) explained the observed increase in surface runoff potential of the watershed, as shown by their calibrated CN values. These findings are reminiscent of the Sahelian hydrological paradox reported in the literature and provide evidence of the sensitivity of surface runoff to LULC changes. Overall, the results call to hydrologists, water resources planners and managers, regarding the advantages of coupling LULC changes in hydrological modelling. Also, the study advocates for the development of integrated modelling platforms integrating both LULC changes and hydrological modelling to allow a better understanding and the more accurate long-term forecasting of water resources, in particular in the case of Sahelian hydrosystems.Keywords: Dynamic LULC input, Hydrological modelling, Surface runoff, SWAT model, Burkina Faso, Sahelian paradox.

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Forecasting the Effects of Land Use Scenarios on Farmland Birds Reveal a Potential Mitigation of Climate Change Impacts

PLoS ONE ◽

10.1371/journal.pone.0117850 ◽

2015 ◽

Vol 10 (2) ◽

pp. e0117850 ◽

Cited By ~ 14

Author(s):

Karine Princé ◽

Romain Lorrillière ◽

Morgane Barbet-Massin ◽

François Léger ◽

Frédéric Jiguet

Keyword(s):

Climate Change ◽

Land Use ◽

Climate Change Impacts ◽

Farmland Birds ◽

Land Use Scenarios ◽

Effects Of Land Use

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Impact Evaluation of Future Climate and Land Use Scenarios on Water and Sediment Regime using Distributed Hydrological Modelling in a Tropical Rainforest Catchment in West Java (Indonesia)

10.4995/thesis/10251/153152 ◽

2020 ◽

Author(s):

Shantosa Yudha Siswanto

Keyword(s):

Land Use ◽

Impact Evaluation ◽

Tropical Rainforest ◽

Hydrological Modelling ◽

Future Climate ◽

West Java ◽

Water And Sediment ◽

Land Use Scenarios ◽

Distributed Hydrological Modelling

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The potential for land use change to reduce flood risk in mid-sized catchments in the Myjava region of Slovakia

Contributions to Geophysics and Geodesy ◽

10.1515/congeo-2017-0007 ◽

2017 ◽

Vol 47 (2) ◽

pp. 95-112 ◽

Cited By ~ 2

Author(s):

Peter Rončák ◽

Evelin Lisovszki ◽

Ján Szolgay ◽

Kamila Hlavčová ◽

Silvia Kohnová ◽

...

Keyword(s):

Land Use ◽

Soil Erosion ◽

River Basin ◽

Surface Runoff ◽

Management Practices ◽

Agricultural Land ◽

Arable Land ◽

Land Use Management ◽

Land Use Scenarios ◽

The Impact

AbstractThe effects of land use management practices on surface runoff are evident on a local scale, but evidence of their impact on the scale of a watershed is limited. This study focuses on an analysis of the impact of land use changes on the flood regime in the Myjava River basin, which is located in Western Slovakia. The Myjava River basin has an area of 641.32 km2and is typified by the formation of fast runoff processes, intensive soil erosion, and muddy floods. The main factors responsible for these problems with flooding and soil erosion are the basin’s location, geology, pedology, agricultural land use, and cropping practices. The GIS-based, spatially distributed WetSpa rainfall-runoff model was used to simulate mean daily discharges in the outlet of the basin as well as the individual components of the water balance. The model was calibrated based on the period between 1997 and 2012 with outstanding results (an NS coefficient of 0.702). Various components of runoff (e.g., surface, interflow and groundwater) and several elements of the hydrological balance (evapotranspiration and soil moisture) were simulated under various land use scenarios. Six land use scenarios (‘crop’, ‘grass’, ‘forest’, ‘slope’, ‘elevation’ and ‘optimal’) were developed. The first three scenarios exhibited the ability of the WetSpa model to simulate runoff under changed land use conditions and enabled a better adjustment of the land use parameters of the model. Three other “more realistic” land use scenarios, which were based on the distribution of land use classes (arable land, grass and forest) regarding permissible slopes in the catchment, confirmed the possibility of reducing surface runoff and maximum discharges with applicable changes in land use and land management. These scenarios represent practical, realistic and realizable land use management solutions and they could be economically implemented to mitigate soil erosion processes and enhance the flood protection measures in the Myjava River basin.

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