Assessment of Climate Change and Associated Vegetation Cover Change on Watershed-Scale Runoff and Sediment Yield

Abstract

Climate change has an important impact on water balance and material circulation in watersheds. Quantifying the influence of climate and climate-driven vegetation cover changes on watershed-scale runoff and sediment yield will help to deepen our understanding of the environmental effects of climate change. Taking the Zhenjiangguan Watershed in Sichuan Province, China as a case study, three downscaled general circulation models with two emission scenarios were used to generate possible climatic conditions for three future periods of P1 (2020–2039), P2 (2050–2069) and P3 (2080–2099). Differences in scenarios were compared with the base period 1980–1999. Then, a Normalized Difference Vegetation Index climate factor regression model was established to analyze changes to vegetation cover under the climate change scenarios. Finally, a Soil and Water Assessment Tool model was built to simulate the response of runoff and sediment yield in the three future periods under two different scenarios: only changes in climate and synergistic changes in climate and vegetation cover. The temperature and precipitation projections showed a significant increasing trend compared to the baseline condition for both emission scenarios. Climate change is expected to increase the average annual runoff by 15%–38% compared with the base period, and the average annual sediment yield will increase by 4%–32%. The response of runoff and sediment yield varies in different periods, scenarios, and sub-watersheds. Climate-driven vegetation cover changes have an impact on runoff and sediment yield in the watershed, resulting in a difference of 5.8%–12.9% to the total changes. To some extent, the changes in vegetation cover will inhibit the hydrological impact of climate changes. The study helps to clarify the effects of climate and vegetation cover factors on hydrological variations in watersheds and provides further support for understanding future hydrological scenarios and implementing effective protection and use of water and soil resources.

Evaluation of the Impacts of Climate Change on Sediment Yield from the Logiya Watershed, Lower Awash Basin, Ethiopia

“…Getahun and Lanen [86] reported projected change in main rainy season precipitation with less than ±20% in all GCMs in the Upper Awash River Basin. The predicted increase of precipitation was unevenly distributed in a year, which would further increase the seasonal variation of precipitation in the watershed [19].…”

“…The rising GHG concentration due to continued gas emissions from different sources to the atmosphere affects climate variables and consequently alters hydrological cycles [10,[12][13][14][15]. The change in climate-mainly due to precipitation and temperature patterns-could significantly influence soil erosion rates, streamflow, and sediment yield, which (directly or indirectly) adversely affects water resource availability and ecosystems [13,[16][17][18][19]. In connection to this, numerous studies have indicated that changes in precipitation, temperature, and the interactions of these with land use and land cover change (LULCC) will be the main climate change related stress expected to exacerbate soil loss and sediment transport [20][21][22][23].…”

“…Over the past decade, the impacts of climate change on sediment yields have been widely studied around the globe [13,19,[25][26][27][28]. Also, studies show that sediment transport is highly influenced by extreme precipitation and river discharge due to the non-linear relationship between water discharge and sediment transportation rates [29].…”

“…Moreover, Francipane et al [25] reported that the magnitudes of mean and extreme events of sediment yield are expected to decrease with a high probability in the Walnut Gulch Experimental watershed in southeastern Arizona, USA. However, on their part, Zhang et al [19] indicated that climate change is expected to increase the annual average sediment yield by 4-32% when compared to the base period for the Zhenjiangguan watershed, China. Azim et al [12] examined the impact of climate change on the sediment yield of the Naran watershed, Pakistan using global climate model (GCM) predictors from the Special Report on Emission Scenarios (SRES) A2 and B2 and found mean annual sediment yield increases of 5-6% and 9-11% under the A2 and the B2 scenarios for time horizons of 2011-2040 and 2041-2070, respectively.…”

Assessing the Impact of Man–Made Ponds on Soil Erosion and Sediment Transport in Limnological Basins

“…The processes of soil erosion and sediment transport take part in van Rijn's (1993) [3] sedimentary cycle, and often are the main causes of soil loss in basins [4]. Although these processes are of natural origin [5], the interaction between climate, soil, topography, land use, and land cover significantly influence erosion rates and sediment loads [6,7]. Soil loss due to these processes is a frequent problem that hydrologists, land planners and basin managers will need to deal with [8].…”