Analysis of Agricultural Land Use Change in the Middle Reach of the Heihe River Basin, Northwest China

Abstract

The Heihe River Basin (HRB) is the second largest inland river basin in arid Northwest China. The expanding agricultural irrigation, growing industrialization, and increasing urban development in the middle reach have depleted much of the river flow to the lower reach, degrading the corresponding ecosystems. Since the enactment of the State Council of China’s new HRB water allocation policy in 2000 tremendous land use and land cover (LULC) changes have taken place to reduce water consumption in the middle reach and deliver more water downstream. This paper analyzes LULC changes during the period of 2000–2009 to understand how the changing land use patterns have altered water resource dynamics in the region. Results, while yet to be further verified in the field, show that from 2000 to 2009, urban, agricultural land, rangeland, and forest areas have increased, and barren area has decreased. Within the cropland, rice (a high water consumption crop) planting area decreased, while corn and wheat (relatively lower water consumption crops) planting areas increased. These changes in land use patterns, especially in the agricultural zones, have ensured the discharge of the required amount of water to the lower reach.

Expansion of agricultural oasis in the Heihe River Basin of China: Patterns, reasons and policy implications

“…They found that farmland and water areas in middle reaches of HRB increased by 25.53% and 109.21% during 1985-1997, respectively. Although the changes in water areas of Fu et al (2014) is different from our researches, the water areas changes (increased by 109.21% during 1985-1997) assessed by Lu et al (2003) is similar to our research (increased by 162.02% during 1986-2000). In addition, the farmland expansion rate (25.53%) of Lu et al (2003) is also very similar to our research (24.41%).…”

“…However, the change trend of water areas is a little different. Water areas in middle reaches of HRB showed negative change trend in our research while that of Fu et al (2014) present a negative change trend. In spite of the difference in research period, the unmatched land use classification of water areas could also attribute to the difference.…”

“…Fu et al (2014) found that the human activities have significantly changed the distribution and allocation of limited water resource in the basin, resulting in the expansion of oases. Zhou et al (2015) believe that rapid agricultural and economic development leads to an expansion of constructed oases and considerable contraction of the oasis-desert transitional zone.…”

“…On the basis of two sets of 30 m resolution Landsat 5 and 7 images, Fu et al (2014) mapped the land uses in the middle reaches of the HRB in 2000 and 2009. They found that the barren land and ice and snow in the middle reaches of HRB decreased by 15.66% and 88.44%, respectively while agricultural land, range land, forest and water areas had expanded by 20.24%, 16.56%, 5.91% and 144.27% respectively during 2000-2009.…”

Evolution of the vegetation system in the Heihe River basin in the last 2000 years

“…The HRB is a typical inland river ecosystem, which includes natural vegetation, irrigated crop, desert and terminal lakes. The middle course of the basin has an agricultural history over more than 2000 years, while the lower reaches are located at the alluvial fan -supporting local human civilization and ecosystem development (Fu et al, 2014). Increasing agricultural development and changing climate and hydrology over the past 2000 years have significantly changed use of land and water resources and have modified the catchment vegetation system (Lu et al, 2015a;Zhao et al, 2016).…”