Soil water content variations and hydrological relations of the cropland-treebelt-desert land use pattern in an oasis-desert ecotone of the Heihe River Basin, China

Abstract

This study considered the cropland-treebelt-desert system in the arid inland river basin as an entire continuum to investigate the soil water content variation and hydrological relation. For this objective, the volumetric soil water content and plant root distribution was measured to 300 cm depth along a cropland-treebelt-desert site at the oasis-desert ecotone in the Heihe River Basin, China. The results showed that the mean soil water content in the 0-200 cm layer was greater in the cropland (8.88%) than that in the treebelt (5.78%) and desert (4.37%) as a result of frequent irrigation events. However, the cropland had noticeably lower mean soil water content below 200 cm depth (14.27%), compared to treebelt (18.07%) and desert (17.30%) with deeper roots to suck up groundwater. The decline process in soil water content pulse of the cropland and treebelt after irrigation event could be well described by an exponential decay function, and the soil water loss rate was greater in the cropland (0.45-0.70%/day) than that in the treebelt (0.32-0.47%/day). The hydrological relation between treebelt and cropland in the upper soil layer was mainly occurred by treebelt root water uptake from cropland. The biomass of fine treebelt root extended into the cropland decreased logarithmically with the distance from the cropland-treebelt interface, which resulted in the smaller soil water content in the cropland with more proximity to the treebelt. The hydrological relation in the lower soil layer among cropland-treebelt-desert was caused by groundwater recharge, as cropland irrigation raised up the groundwater level to replenish the deep soil layer. The results indicated that the percolation in the cropland was an important water source for the growth of treebelt and desert plants. This study could provide scientific basis for land use pattern design and water resources management in the arid inland river basin.

Fine root distributions of shelterbelt trees and their water sources in an oasis of arid northwestern China

“…5). This result was in agreement with other studies on shelterbelt trees in arid regions (Woodall and Ward, 2002;Shen et al, 2014). The findings of this study indicate that large amounts of available water from both cropland irrigation and irrigation channel leakage promoted root growth near the border between the shelterbelt and the irrigated cropland.…”

Spatial-temporal variability of soil water content in a cropland-shelterbelt-desert site in an arid inland river basin of Northwest China

“…The soil profile was divided into five layers (0-20 cm, 20-120 cm, 120-160 cm, 160-240 cm, and 240-280 cm) according to the measured soil properties. Please refer to the detailed soil properties in Table 1 of Shen et al (2014). (Fig.…”

“…The combinations of land use or vegetation type had substantial effects on the variations of soil water, especially in arid and semiarid regions (She et al, 2014;Shen et al, 2014). In the oasis-desert ecotone of the arid inland river basin such as the Heihe River Basin in China, irrigation and groundwater support both natural and agricultural ecosystems.…”

Evaluation of remote sensing‐based evapotranspiration estimates using a water transfer numerical simulation under different vegetation conditions in an arid area

“…For farmland, estimated daily AET matched well with the HYDRUS‐1D daily AET for both trends and magnitudes (Figure a), demonstrating that the remotely sensed ET r F interpolation method could be used to provide daily AET series during the summer period in irrigated farmlands, even though precipitation and irrigation were not considered directly in the METRIC model process. For the forests distributed in the oasis subarea, moderate agreement was obtained for the daily AET series estimated using remote sensing methods and HYDRUS‐1D, because remotely sensed AET estimates did not capture the increasing trends of AET, especially the increased evaporation, resulting from precipitation and irrigation events occurring between Landsat image dates (Allen et al, ; Shen et al, ). For the desert subarea, remotely sensed daily AET series were considered to be speculative, even for the AET estimates on satellite overpass days (Figure c).…”