Hydrological Impacts of Land Use Change and Climate Variability in the Headwater Region of the Heihe River Basin, Northwest China

Abstract

Land use change and climate variability are two key factors impacting watershed hydrology, which is strongly related to the availability of water resources and the sustainability of local ecosystems. This study assessed separate and combined hydrological impacts of land use change and climate variability in the headwater region of a typical arid inland river basin, known as the Heihe River Basin, northwest China, in the recent past (1995–2014) and near future (2015–2024), by combining two land use models (i.e., Markov chain model and Dyna-CLUE) with a hydrological model (i.e., SWAT). The potential impacts in the near future were explored using projected land use patterns and hypothetical climate scenarios established on the basis of analyzing long-term climatic observations. Land use changes in the recent past are dominated by the expansion of grassland and a decrease in farmland; meanwhile the climate develops with a wetting and warming trend. Land use changes in this period induce slight reductions in surface runoff, groundwater discharge and streamflow whereas climate changes produce pronounced increases in them. The joint hydrological impacts are similar to those solely induced by climate changes. Spatially, both the effects of land use change and climate variability vary with the sub-basin. The influences of land use changes are more identifiable in some sub-basins, compared with the basin-wide impacts. In the near future, climate changes tend to affect the hydrological regimes much more prominently than land use changes, leading to significant increases in all hydrological components. Nevertheless, the role of land use change should not be overlooked, especially if the climate becomes drier in the future, as in this case it may magnify the hydrological responses.

Effects of Climate Change and Human Activity on Runoff in a Typical Loess Gullied-Hilly Region Watershed

“…It was first adopted by Hirsch et al from Mann-Kendall's test and was later used by Gan to analyze the hydroclimatic trends in Canadian prairies [16][17][18]. This test was used as the analytical tool of choice because the model works for the non-normalities in unusual data reports; and the model has high asymptotic efficiency [19]. In addition, moving t-test and hopped parameter were used to validate the Mann-Kendall test.…”

Effects of changes in land use and climate on water availability of a tropical catchment

“…climatic interference (Calder et al, 2001;Blöschl et al, 2007;Beck et al, 2013). Several studies show that the combination of land use and climate changes does not necessarily result in accelerating changes in hydrological processes (Legesse et al, 2003;Khoi & Suetsugi, 2014), since the effects of both drivers may also offset each other (Zhang et al, 2016). In addition, feedback mechanisms between land use change and climate change may be operative in larger catchments, however to what extent and in which direction is not very well understood (Pielke, 2005;Blöschl et al, 2007;Wohl et al, 2012).…”

“…However, it is a challenge to measure the effectiveness of land use planning for improving availability of water resources due to climatic interference. Complex interactions between land use and climate changes may not only result in accelerating changes in hydrological processes (Legesse et al, 2003;Khoi & Suetsugi, 2014), but may also offset each other (Zhang et al, 2016), which requires further study.…”

“…For example, Zhang et al (2016) used a combination of a Markov chain model and a Dynamic Conversion of Land Use and its Effects (Dyna-CLUE) model to simulate future land uses, climate change scenarios to predict future climate variability and the Soil and Water Assessment Tool (SWAT) model to simulate hydrological processes in order to quantify the hydrological impacts of land use and climate changes. However, very few studies have assessed hydrological impacts due to land use and climate changes in tropical regions, which is mainly due to limited hydrological data in tropical regions for model calibration and validation purposes (Douglas, 1999).…”

“…Numerous studies argue that different types of land use have different water use and water storage characteristics, thus different land use distributions may result in different distributions of water in space and time (Bruijnzeel, 1989;Sahin & Hall, 1996;Brown et al, 2005;Romanowicz & Booij, 2011;Gumindoga et al, 2014a;Zhang et al, 2016;Marhaento et al, 2017a). Studies in tropical regions have shown that changes from vegetated areas into settlements may significantly reduce canopy interception and soil infiltration capacity, resulting in a large fraction of precipitation being transformed into surface runoff (Bruijnzeel, 2004;Valentin et al, 2008;Marhaento et al, 2017a).…”