Land use/land cover change responses to ecological water conveyance in the lower reaches of Tarim River, China

Abstract

The Tarim River is the longest inland river in China and is considered as an important river to protect the oasis economy and environment of the Tarim Basin. However, excessive exploitation and over-utilization of natural resources, particularly water resources, have triggered a series of ecological and environmental problems, such as the reduction in the volume of water in the main river, deterioration of water quality, drying up of downstream rivers, degradation of vegetation, and land desertification. In this study, the land use/land cover change (LUCC) responses to ecological water conveyance in the lower reaches of the Tarim River were investigated using ENVI (Environment for Visualizing Images) and GIS (Geographic Information System) data analysis software for the period of 1990-2018. Multi-temporal remote sensing images and ecological water conveyance data from 1990 to 2018 were used. The results indicate that LUCC covered an area of 2644.34 km 2 during this period, accounting for 15.79% of the total study area. From 1990 to 2018, wetland, farmland, forestland, and artificial surfaces increased by 533.42 km 2 (216.77%), 446.68 km 2 (123.66%), 284.55 km 2 (5.67%), and 57.51 km 2 (217.96%), respectively, whereas areas covered by grassland and other land use/land cover types, such as Gobi, bare soil, and deserts, decreased by 103.34 km 2 (14.31%) and 1218.83 km 2 (11.75%), respectively. Vegetation area decreased first and then increased, with the order of 2010<2000<1990<2018. LUCC in the overflow and stagnant areas in the lower reaches of the Tarim River was mainly characterized by fragmentation, irregularity, and complexity. By analyzing the LUCC responses to 19 rounds of ecological water conveyance in the lower reaches of the Tarim River from 2000 to the end of 2018, we proposed guidelines for the rational development and utilization of water and soil resources and formulation of strategies for the sustainable development of the lower reaches of the Tarim River. This study provides scientific guidance for optimal scheduling of water resources in the region.

Research on Vegetation Coverage Dynamics and Prediction in the Taitema Lake Region

“…With the continuous implementation of EWCP, the groundwater level in the lower reaches of the Tarim River has increased [13,14,16,17,19], and the ecological water level has held steady at 4-6 m. The water is most abundant when the groundwater level is 6 m in arid regions, and trees, such as Populus euphratica and Tamarix ramosissima, grow well and thrive. When the groundwater level is 0-4 m, obvious niche overlap of trees, shrubs, and herbs is observed [40].…”

“…The studies on the middle and lower reaches of the Tarim River over different time periods show varying results, which refer to the characteristics of water and salt transport in desert riparian forests [18], the response of groundwater levels [19], the characteristics of spatial changes in surface water bodies [20,21], water-use efficiency [22], and ecological environment response [16]. Besides, the vegetation dynamic in the Taitema Lake region remains unclear, especially its future vegetation dynamic with the implementation of the ecological water conveyance project in the region.…”

Ecohydrological effects of water conveyance in a disconnected river in an arid inland river basin

“…Except for the years 2006, 2007 and 2009, the river water reached the river's terminal, Taitema Lake, most of the time, delivering 84.45 × 10 8 m 3 of ecological water to the lower reaches of the river (Table 1 ). The total amount of groundwater and aeration zone recharged through river infiltration along the course of the river was about 30.6 × 10 8 m 3 and 42.15 × 10 8 m 3 , respectively, and the amount of water entering Taitema Lake was about 11.7 × 10 8 m 3 , accounting for 36.23%, 49.92% and 13.85% of total water delivered, respectively 31 .…”

“…The Simpson diversity index reflects the species’ variation in number and biological diversity, the McIntosh index reflects the species’ evenness, and the Margalef index reflects their richness. In the sample site survey, the following methods were used in the calculations 31 , 32 . where S is the number of species, N is the total number of individuals of all plants, A is the sample area, n i is the number of individuals of the i- th species, and P i is the proportion of the multiplicity of the i- th species, i.e., the importance value.…”

Study on the Relationship between Water Resources Utilization and Economic Growth in Tarim River basin from the Perspective of Water Footprint

“…Tarim River is the mother river of all ethnic groups in Southern Xinjiang [1]. Scholarly research on water resources in Tarim River basin is mainly carried out from the perspectives of utilization [2,3], change trend [4], utilization and ecological conservation [5], ecological compensation [6], carrying capacity [7][8][9], the economic effect of allocation and utilization [10], water price adjustment [11], supervision [12] and research progress [1]. There are few studies on the coordination of water resource utilization and economic development in the Tarim River basin.…”