Numerical Simulations of the Impacts of Mountain on Oasis Effects in Arid Central Asia

Abstract

Abstract:The oases in the mountain-basin systems of Central Asia are extremely fragile. Investigating oasis effects and oasis-desert interactions is important for understanding the ecological stability of oases. However, previous studies have been performed only in oasis-desert environments and have not considered the impacts of mountains. In this study, oasis effects were explored in the context of mountain effects in the northern Tianshan Mountains (NTM) using the Weather Research and Forecasting (WRF) model. Four numerical simulations are performed. The def simulation uses the default terrestrial datasets provided by the WRF model. The mod simulation uses actual terrestrial datasets from satellite products. The non-oasis simulation is a scenario simulation in which oasis areas are replaced by desert conditions, while all other conditions are the same as the mod simulation. Finally, the non-mountain simulation is a scenario simulation in which the elevation values of all grids are set to a constant value of 300 m, while all other conditions are the same as in the mod simulation. The mod simulation agrees well with near-surface measurements of temperature, relative humidity and latent heat flux. The Tianshan Mountains exert a cooling and wetting effects in the NTM region. The oasis breeze circulation (OBC) between oases and the deserts is counteracted by the stronger background circulation. Thus, the self-supporting mechanism of oases originating from the OBC plays a limited role in maintaining the ecological stability of oases in this mountain-basin system. However, the mountain wind causes the "cold-wet" island effects of the oases to extend into the oasis-desert transition zone at night, which is beneficial for plants in the transition region.

Seasonal and Inter-Annual Variability of Groundwater and Their Responses to Climate Change and Human Activities in Arid and Desert Areas: A Case Study in Yaoba Oasis, Northwest China

“…Hence, the evaporation showed an insignificant increase afterwards from 1987.09 mm in 2007 to 2264.72 mm in 2018. According to previous research results, the intense evaporation in the arid region mostly exhausted the flood formed during the rainstorm season before it infiltrated into the groundwater [16,47]. In addition, water diversion and irrigation during the agricultural production increased the groundwater level and caused it to exceed the critical depth, resulting in continuous strong water evaporation in the shallow phreatic water area of the western part of study region, which worsened soil salinization [27,48,49].…”

Numerical Simulation of the Irrigation Effects on Surface Fluxes and Local Climate in Typical Mountain‐Oasis‐Desert Systems in the Central Asia Arid Area

“…Based on our previous simulations without adding the irrigation process, the cold (wet) island effects of oases were as large as ‐0.61 °C (1.56 g/kg), and the divergent wind blowing from the center of the oasis area to the surrounding desert was approximately 1.5 m/s in the daytime, but due to stronger background valley winds (more than 3 m/s), the divergence was counteracted most of the time during the day ( M Zhang, Luo, Hamdi, et al, ). The comparison between this prior work with the results in this paper illustrates that the WRF‐Noah model without irrigation processes underestimates the intensities of the cold, wet island effects of oases.…”

Influencing Factors of the Spatial–Temporal Variation of Layered Soils and Sediments Moistures and Infiltration Characteristics under Irrigation in a Desert Oasis by Deterministic Spatial Interpolation Methods

“…However, the surface runoff formed during the rainstorm season often appears as a flood peak with large flow and short duration. After the rain, this runoff was exhausted by evaporation and leakage [4]. All the aforementioned factors contributed to the identified spatial distribution pattern of soil moisture in the Yaoba Oasis.…”

“…Oasis is the most frequent and active region of human activities in arid areas in the world [1], such as the Middle East, Mexico, most parts of Africa, parts of northwestern America, and pockets of India, Central Asia, and northwestern China [2]. Oasis is also the guarantee and support of the opening up and cooperation of the social and economic development along the Silk Road [3,4]. The development and evolution of oasis mainly depends on ground water supply due to the extreme scarcity of surface water resources [5][6][7].…”