Effects of Sponge City Development on Soil Moisture and Water Quality in a Typical City in the Loess Plateau in China

Abstract

Changes in soil moisture following the establishment of sponge cities play a key role in the regulation of the relationship between surface runoff and rain resources in arid and semi-arid regions of the Loess Plateau. Based on soil moisture and rainfall monitoring data obtained at the fine-scale (per 10-cm depth and hourly), temporal and spatial variation in soil moisture under different sponge measures and their responses to rain events were analyzed, in addition to water quality changes were investigated by water sampling. The results showed, from 2000 to 2018, the area of farmland greatly decreased from 56.88 to 5.02% in Guyuan, while the area of construction land increased from 29.24 to 45.96%. The area of changes in Guyuan accounted for 63.68% of the total area. Precipitation in July and August was large, and accounted for 19.11 and 23.24% of the multi-year average precipitation, respectively. The grasslands and sunken green spaces exhibited good water retention effects, with average soil moisture of 14.40 and 13.77% during the study period, and 18.48 and 15.52% during the rain event, respectively. During the rain event, the total nitrogen (TN), ammonia nitrogen (NH 3-N), available phosphorus (AP), and total phosphorus (TP) can be effectively reduced by the sunken green spaces, with average concentrations of 0.79, 0.28, 0.03, and 0.05 mg/L, respectively. The development of sponge measures could improve the urban ecological environment and hydrological conditions in the Loess Plateau, and increase the potential utilization of urban rainwater resources.

Identifying the characteristics of and factors driving spatiotemporal water quality variations in the Yellow River Basin, China, from 2008 to 2020

“…Spatiotemporal variations in different water quality parameters can be directly determined by analyzing monitoring data. Indicators such as dissolved oxygen (DO), permanganate index (CODMn), ammonia nitrogen (NH3-N), total nitrogen (TN), and total phosphorus (TP) have received much attention in the field of spatiotemporal dynamics of water quality (Jia et al, 2020;Sun et al, 2019). DO reflects the self-purification capacity of water as it is related to oxygen concentration in aquatic environments (Nugraha et al, 2020).…”

Study on Waterlogging Reduction Effect of LID Facilities in Collapsible Loess Area Based on Coupled 1D and 2D Hydrodynamic Model

“…Moreover, the sponge city construction in the loess region of China has just entered the research stage; the sponge measures adopted in pilots of the loess areas are different from those in other cities, and with few studies carried out to evaluate its effect [27,28]. Despite the fact that runoff reduction performance of pilot sponge cities is widely recognized in humid regions, waterlogging reduction is still a new practice in the loess region, and it is still subject to further research to answer the following questions:…”