Preprints
https://doi.org/10.5194/hess-2021-538
https://doi.org/10.5194/hess-2021-538

  08 Nov 2021

08 Nov 2021

Review status: this preprint is currently under review for the journal HESS.

Description and application of a distributed hydrological model based on soil–gravel structure in the Qinghai–Tibet Plateau

Pengxiang Wang1,2, Zuhao Zhou1, Jiajia Liu1, Chongyu Xu2,6, Kang Wang2, Yangli Liu3, Jia Li4, Yuqing Li5, Yangwen Jia1, and Hao Wang1 Pengxiang Wang et al.
  • 1State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin, China Institute of Water Resources and Hydropower Research, Beijing 100038, China
  • 2State Key Laboratory of Water Resources and Hydropower Engineering Science, Wuhan University, Wuhan 430072, China
  • 3China Power Construction Group Guiyang Engineering Corporation Limited, Guiyang 550081, China
  • 4Bureau of South to North Water Transfer of Planning, Designing and Management, Ministry of Water Resources, Beijing 100038, China
  • 5Department of Water Resources and Civil Engineering, Tibet Agriculture and Animal Husbandry College, Nyingchi 860000, China
  • 6Department of Geosciences, University of Oslo, Oslo, Norway

Abstract. The Qinghai–Tibet Plateau, known as the “Asian Water Tower”, has a thin soil layer with a thick gravel layer underneath. Its unique geological structure, combined with widespread snow and frozen soil in this area, profoundly affect the water circulation processes of the entire region. To thoroughly study the water cycle mechanism of the Qinghai–Tibet Plateau, this study considered the geological and climatic characteristics of this area and selected the Niyang River Basin as the study area. The Water and Energy transfer Processes in the Qinghai–Tibet Plateau (WEP-QTP) model was constructed based on the original Water and Energy transfer Processes in Cold Regions (WEP-COR) model. This model divides the single soil structure into two types of media: the soil layer and gravel layer. In the non-freeze–thaw period, two infiltration models based on the dualistic soil–gravel structure were developed based on the Richards equation in non-heavy rain periods and the multi-layer Green–Ampt model in heavy rain periods. During the freeze–thaw period, a hydrothermal coupling model based on the continuum of the snow–soil–gravel layer was constructed. This distributed hydrological model can dynamically simulate the changes in frozen soil and flow processes in this area. The addition of the gravel layer corrected the original model’s overestimation of the moisture content of the soil layer below the surface soil and reduced the moisture content relative error (RE) from 33.74 % to −12.11 %. The addition of the snow layer not only reduces the temperature fluctuation of the surface soil, but also works with the gravel layers to revise the original model’s overestimation of the freeze–thaw speed of the frozen soil. The temperature RE was reduced from −3.60 % to 0.08 %. In the non-freeze–thaw period, the dualistic soil–gravel structure improved the regulation effect of groundwater on flow, stabilizing the flow process. The maximum RE at the flow peak and valley decreased by 88.2 % and 21.3 %, respectively. In the freeze–thaw period, by considering the effect of the snow–soil–gravel layer continuum, the change in the frozen soil depth of WEP-QTP lags behind that of WEP-COR by approximately one month. There was more time for the river groundwater recharge, which better shows the “tailing” process after October. The flow simulated by the WEP-QTP model was more accurate and closer to the actual measurements, with Nash > 0.75 and |RE| < 10 %. The improved model reflects the effects of the Qinghai-Tibet Plateau special environment on the hydrothermal transport and water cycle process and is suitable for hydrological simulation of the Qinghai-Tibet Plateau.

Pengxiang Wang et al.

Status: open (until 04 Jan 2022)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse

Pengxiang Wang et al.

Pengxiang Wang et al.

Viewed

Total article views: 271 (including HTML, PDF, and XML)
HTML PDF XML Total BibTeX EndNote
226 40 5 271 2 3
  • HTML: 226
  • PDF: 40
  • XML: 5
  • Total: 271
  • BibTeX: 2
  • EndNote: 3
Views and downloads (calculated since 08 Nov 2021)
Cumulative views and downloads (calculated since 08 Nov 2021)

Viewed (geographical distribution)

Total article views: 242 (including HTML, PDF, and XML) Thereof 242 with geography defined and 0 with unknown origin.
Country # Views %
  • 1
1
 
 
 
 
Latest update: 01 Dec 2021
Download
Short summary
Combining the geological characteristics of the thin soil layer on the thick gravel layer and the climate characteristics of the long-term snow cover of the Qinghai-Tibet Plateau, the WEP-QTP hydrological model was constructed by dividing a single soil structure into soil and gravel. In contrast to the general cold area, the special environment of the Qinghai–Tibet Plateau affects the hydrothermal transport process, which can not be ignored in hydrological forecast and water resource assessment.