Estimation and Restoration of Dried Soil Layers in the Slope-gully Unit
of the Chinese Loess Plateau
Abstract
Dried soil layer (DSL) is a common phenomenon forms by soil moisture
deficiency in the Chinese Loess Plateau (CLP). In order to reveal the
temporal stability and elimination degree of DSLs, we obtained the 19
occasions data of soil water content (SWC) at 15 observation sites in a
typical slope-gully unit. The available soil moisture (ASM) and DSL were
estimated by representative sites which determined through the temporal
stability method, and then assessed the reliability of simulation
equations between representative locations condition and mean conditions
of the study area. Results show that: (1) The temporal dynamics of DSL
were characterized with somewhat complexity. The ASM within the DSL
(DSL-ASM), ASM within the sandwiched dried soil layer (SDSL-ASM) and
quantitative index (QI) varied within the range of 2.75%–3.11%,
2.98%–4.22% and 0.254–0.356, respectively. (2) The possibility of
development and recovery for DSL and SDSL in deep layers were less than
that in surface layers. The maximum depth of DSL (DSLMD) was
significantly and negatively related to the SDRD of DSL-ASM, the maximum
depth of SDSL (SDSLMD) was negatively related to the SDRD of SDSL-ASM.
(3) The prediction results of ASM above 300 cm depth were more accurate
than other layers ( R 2=0.89). The DSL-ASM has
a more prediction accurate than SDSL-ASM and QI. On the analysis of the
time stability characteristics of ASM and dried soil layers, A2 and C3
can better represent the mean conditions of ASM at the depth of three
and four soil layers, respectively. C2, A1 and A1 can better represent
the average levels of DSL-ASM, SDSL-ASM and QI, respectively ( R
2=0.43, 0.14 and 0.18). (4) The restoration degrees of
DSLs mainly showed no elimination and slight elimination, the DSLs
cannot be completely eliminated within a short time. Scientific
regulation of soil moisture can alleviate the formation and development
of DSLs a certain extent, and provide the possibility for DSLs
restoration.