The eastern Tibetan Plateau is subjected to strong spatial variations in precipitation, but the underlying reasons are still not well understood due to sparse in-situ meteorological observations. In this study, streamflow observations were adopted to investigate the orographic controls on precipitation in the Qingyijiang (QYJ) Basin of the eastern Tibetan Plateau. The method of multi-year annual water balance was used to estimate the basin-level precipitation using in-situ streamflow and flux-based evapotranspiration. In addition, elevation transect was designed to examine the possible links between precipitation and geomorphology. The results showed the severe under-estimation of regional precipitation by weather sites (~1150 mm yr⁻¹) in the QYJ Basin, where the runoff depth was as high as ~1450 mm yr⁻¹. The water balance revealed a much higher level of precipitation (~2000 mm yr⁻¹) in the QYJ Basin, but precipitation in the two adjacent basins was contrastingly low (2200 mm) on or near the bottom of the horn-mouth geomorphology than the others (<1800 mm). With these results, we concluded that the high precipitation level in the QYJ Basin could be attributed to the combined converging and lifting effects of geomorphology on the westward atmospheric vapor. Therefore, flooding risk should be carefully accounted for in the basins with similar geomorphology in the eastern Tibetan Plateau.

Alternate moistube-irrigation is a new type of water-saving irrigation, and research on water infiltration with alternate moistube-irrigation is important for the design of irrigation schemes and helpful to understand and apply this technology. The effects of the pressure head (1.0 m and 1.5 m) and tube spacing (10 cm, 20 cm, and 30 cm between two moistubes respectively) on soil water infiltration in alternate moistube-irrigation were studied in laboratory experiments, and the cumulative infiltration, discharge of the moistube, and shape and water distribution of the cross-section of the wetting front were determined. The cumulative infiltration increased quickly and linearly with the infiltration time at 0-96 h (R2>0.99), and changed smoothly at 96-192 h with a basically steady infiltration rate. The discharge of the moistube increased rapidly at the beginning of irrigation, then decreased before stabilizing. The cumulative infiltrations and discharges of moistube under the 1.5 m pressure head were more than those under the 1.0 m pressure head. The shape of the cross-section of the wetting front for a single moistube was similar to a concentric circle. With the increase of tube spacing, the interaction between water infiltrations of two moistubes decreased. The soil water distributions around two moistubes were similar to each other under the 1.0 m pressure head and large tube spacing. When the tube spacing was 20 cm, the soil water distribution was more uniform around two moistubes. Keywords: alternate irrigation, moistube-irrigation, soil water infiltration, water use efficiency, water-saving irrigation DOI: 10.25165/j.ijabe.20201304.5297 Citation: Shen L X, Zhang Y M, Yang M, Liu R H. Effects of alternate moistube-irrigation on soil water infiltration. Int J Agric & Biol Eng, 2020; 13(4): 151–158.

Global climate change is increasing extreme rainfall events, and severe floods are becoming more frequent. Flood storage and detention basins (FSDBs) are an important part of the flood control system in China. They play a key role in regional flood emergency response and regulation. Therefore, accurate simulation of flood evolution after the activation of FSDBs is urgently needed. This study proposes a high-accuracy flood evolution simulation method that combines terrain clustering and physical propagation constraints. We first build a 2 m resolution digital elevation model (DEM) using GF-7 stereo imagery and laser altimetry data. We then introduce an improved superpixel segmentation algorithm (TSLIC). This method reduces the number of computational units while preserving key micro-topographic features. It groups high-resolution grids into terrain units with similar elevation characteristics and continuous spatial structure. Based on these terrain units, we develop a flood evolution model called RS-CFPM. The model combines flow velocity estimated from the Manning equation with flood propagation speed derived from radar remote sensing. It uses a water balance framework and includes a propagation time delay constraint. This design helps overcome the limitation of traditional static inundation methods that ignore flood travel time. We apply the proposed method to simulate the flood inundation process during the “23·7” extreme basin-scale flood event in the Haihe River Basin. Comparison with multi-temporal radar observations shows that the errors of simulated water level and inundation extent in the Dongdian FSDB are both within 10%. The computational efficiency is also improved by more than 60% compared with traditional methods. This study provides a new approach for rapid and accurate simulation of flood inundation processes in FSDBs under emergency conditions. The method can support flood emergency operation and decision-making.