Chaohao Xu

Annual Runoff is Highly Linked to Precipitation Extremes in Karst Catchments of Southwest China

AbstractKarst landforms cover 7%–12% of the Earth’s continental area and provide water resources for 25% of the global population. Climate, particularly frequent climate extremes, may greatly affect the annual runoff, especially in climate-sensitive regions such as a karst area of southwest China. Knowledge of the linkage between climate and runoff is urgently needed for smart water resources management. This study therefore selected five catchments that have different carbonized rock coverage (from 11% to 64%) to detect the dominant climatic variables driving changes in annual runoff for the period of 1957–2011 in southwest China. Because climatic variables are highly codependent, a partial least squares regression (PLSR) was used to elucidate the linkages between runoff and 17 climatic variables. Results indicated that the dominant climatic factors driving annual runoff are annual total precipitation, rainy days, heavy precipitation amount, heavy precipitation days, rainstorm amount, and rainstorm days....

Effects of vegetation restoration on soil quality in degraded karst landscapes of southwest China

Vegetation restoration was implemented to control soil erosion in the karst regions of southwest China. It is essential to assess the soil function and quality scientifically during this process and to adopt suitable management practices for this area. However, few studies have been conducted to comprehensively evaluate the effect of vegetation restoration on soil quality in this severely eroded karst area. By taking 302 soil samples from 11 vegetation types, this study investigated the influence of different types of vegetation restoration on soil quality using an integrated soil quality index (SQI) and a generalized linear model (GLM). Vegetation types had significant effects on soil properties and thus on soil quality. SQI was developed by using TN, TP, TK, AP, and clay content; TN had highest weighting values (0.58), which indicated that it contributed the most to final SQI. The highest and lowest SQI values were observed for primary forest and cropland, respectively. Overall, vegetation restoration (e.g., natural restoration, artificial forests and artificial grassland) improved soil quality significantly. A GLM model explained 73.20% of the total variation in SQI, and vegetation type explained the largest proportion (46.39%) of the variation, which implies that the vegetation restoration practices can greatly enhance the soil quality in karst landscapes of southwest China. The results of this study may be used to improve implication of ecological restoration and management in degraded regions.

Prediction of profile soil moisture for one land use using measurements at a soil depth of other land uses in a karst depression

PurposeInformation on root-zone soil water content (SWC) is essential for vegetation restoration, irrigation scheduling, and hydrological modeling. However, measurements of SWC within a variety of land uses may be time-consuming and labor-costing. This study tested whether SWC at a depth of a land use can be used to predict profile SWC of other land uses in terms of temporal stability analysis at a karst depression area in southwest China.Materials and methodsA total of 30 datasets of root-zone SWC from 0.1- to 0.5-m depths were collected by time domain reflectometry probes for three typical land uses from March 12 to November 8, 2015.Results and discussionResults showed that the profile mean SWC and its associated standard deviation (SDP) and coefficient of variation (CVP) differed significantly (P < 0.05) among the grassland, farmland, and forestland. The profile SWC was more temporally stable according to the apparently lower CVT in comparison with CVP. The similarities of the vertical patterns of SWC were strong for the same land uses, while were relatively weak between the different land uses. The SWC measurements of the most temporally stable depth can be used to accurately predict profile SWC for both the same land use and other land uses.ConclusionsThis study further expands the application of the temporal stability analysis and can aid water resource management in areas with diverse land uses.