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2018 Vol.16 No.3
Published 2018-06-30
1
WEN Meili, CHEN Yu, HE Xiaowu, YANG Long, ZHOU Qing
Distribution of collapsed gullies (
Beng Gang
) using GIS and verification of slope aspect selection
[Background]
The distribution pattern of collapsed gully (
Beng Gang
) on different slope aspect can't be tested and quantitively analysed because of different slope aspect standards and acquisition methods in the previous studies. Here we aim to understand the suitability of different methods of extracting and dividing slope aspects in studying the slope direction of collapsed gullies, to verify the conclusion of the selectivity of slope direction in collapsed gully, to clarify the generality and applicability of the selectivity of collapsed slope aspects, and to quantitatively calculate the distribution of collapsed gullies in different slope aspects.
[Methods]
The contours and the boundaries of collapsed gullies as well as the administration boundaries were digitalized in the 1:10 000 topographic map of Youtian town of Wuhua county, Guangdong province. The number and area of collapsed gullies on different slope aspects were calculated by ArcGIS and manual method. The number and area of collapsed gullies in the previous studies were re-counted. 2-slope-aspect refers to the slope aspect is classified into sunny slope and shady slope. 3-slope-aspect refers to the slope aspect is classified into sunny slope, semi-sunny slope and shady slope. 8-slope-aspect refers to the slope aspect is classified into north, northeast, east, southeast, south, southwest, west and northwest.
[Results]
1) Although the number and area of collapsed gullies on every slope aspect were different using two methods in Youtian town, but the distribution law of collapsed gullies was the same, the number and area of collapsed gullies on the sunny and southern slope aspect were separately more than those of the shady and north. Collapsed gullies on the sunny slopes accounted for 66.5% of the total while those on shady slopes accounted for 33.5% in 2-slope-aspect. The gullies on the sunny slope accounted for 45.0% and 16.9% on shady slope in 3-slope-aspect; the gullies on the southern slope accounted for 13.8% and 1.3% north slope in 8-slope-aspect. The area of shady slope land in the town was more than that of the sunny one, and the area of the northern slopes was larger than that of the south slopes. 2) After unifying slope aspect standard, the number and area of collapsed gullies on sunny slope were significantly more than those of the shady ones (
P
<0.05), the gullies on the southern and southwest slopes were more than those on the northern ones. Collapsed gullies on the sunny slope accounted for 70.3% and 29.7% on shady ones in 2-slope-aspect; the collapsed gullies on the sunny slope accounted for 53.5% and 19.4% on shady in 3-slope-aspect; and the collapsed gullies accounted for 20.7% on southern slope, 20.2% on southwest slope and 5.2% on northern in 8-slope-aspect.
[Conclusions]
The slope aspect selection law of collapsed gully in Youtian town of Wuhua county was no relevant to the slope aspect standard or computing method or the slope aspects distribution of the town land. Combing all former studies data after unifying slope standard, collapsed gullies were mainly on sunny slope, the collapsed gullies on south and southwest slopes were the most, and the smallest on north. The quantitative distribution of collapsed gullies on different slope aspects was achieved.
2018 Vol. 16 (3): 1-7 [
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8
LI Ao, WEI Xin, LI Zixuan
Accuracy analysis of land use interpretation of high resolution image in soil erosion dynamic monitoring
[Background]
Soil erosion has a great correlation with land use, and land use directly affects the form, spatial distribution and intensity of soil erosion. High resolution remote sensing image is the main information source of land use status survey, and it is the foundation and precondition to accurately grasp the dynamic soil erosion. The purpose of this study is to improve the interpretation accuracy of land use types for high-resolution images.
[Methods]
Comprehensively supporting soil erosion dynamic monitoring and soil and water conservation planning in county-level, this paper took Huailai county of Hebei province as the study case, and land use information was obtained based on high-resolution image interpretation and field sampling survey. The land use results by the field sampling survey were taken as actual values, and the types (Cultivated land, garden plot, forest land, shrub land, grass land, and other), area and distribution of land use by remote sensing survey were compared with the sampling survey unit analyzed by land use change transfer matrix at the two levels of the whole county.
[Results]
1)The proportion of cultivated land in remote sensing survey and field sampling survey was 16% and 17.1% respectively, with a difference of 1.1%; the proportion of garden plot was 21.8% and 10.7% respectively, with a difference of 11.1%; the proportion of forest land was 16.5% and 8.9% respectively, with a difference of 7.6%; the proportion of shrub land was 14.6% and 33.9% respectively, with a difference of 19.3%; the proportion of grass land was 18.4% and 15.5% respectively, with a difference of 2.9%; the proportion of other land was 12.7% and 13.9%, with a difference of 1.2%. In addition to the far different proportion of garden plot and shrub land, the proportion of other land uses was quite similar, therefore, the land use structure obtained by remote sensing survey and field sampling survey were in good consistency. 2)The precision of cultivated land, garden plot and grass land was higher by remote sensing, 68.2% and 64.2%, respectively, and the forest land was in second, 78.6%, followed by shrub land and other land, 68.2% and 64.2%, respectively. 3)The interpretation accuracy of shrub land by remote sensing was low, only 68.2%, and it was because shrub land and grass land were easily confused so that led to misjudgment, the proportion of the shrub land misjudged to the grass land reached 30.5%.
[Conclusions]
Both methods can be used as reliable means of obtaining land use information, moreover, high-resolution remote sensing images have high value in the investigation and mapping of large scale soil erosion, the misjudgment between the two of the shrub land and the grass land also needs to be paid more attention to the interpretation, the accuracy of interpretation can be improved from the analysis of texture and shade, the increase of field investigation and image processing technology.
2018 Vol. 16 (3): 8-17 [
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18
YANG Wenli, ZHAO Jianmin, ZHU Pingzong, YAN Jingkun, HUANG Guomin
Temporal and spatial distribution characteristics of rainfall erosivity of the Lianshui basin in the red soil region of South China
[Background]
Rainfall erosivity (
R
-factor) is one of the most important factors in the universal soil loss equation (USLE), which directly reflects the potential of soil erosion caused by rainfalls. Due to the unique topography and climate in the red soil region of South China, rainfall erosion force is three times higher in this region than in other regions of China. Therefore, analyses of
R
-factor and its spatial and temporal variations will be valuable for understanding the soil erosion processes in the red soil region, as well as for evaluating soil erosion and conducting soil and water conservation practices.
[Methods]
The
R
-factor was calculated using a simple algorithm model based on monthly precipitation data from four rainfall stations in the Lianshui basin from 2000 to 2016, followed by analyses of temporal and spatial variations of
R
-factor via statistical methods and the ArcGIS spatial analysis. The non-parametric Mann-Kendall test (i.e. the M-K test) was also applied to evaluate the monotonic trend of
R
-factor over the study period.
[Results]
1) Annual
R
values in the Lianshui basin averaged at 5 899.0 MJ·mm/(hm
2
·h·a) from 2000 to 2016, of which the maximum and minimum values were 10 306.9 MJ·mm/(hm
2
·h·a) (2015) and 2 387.1 MJ·mm/(hm
2
·h·a) (2003), respectively. The inter-annual variation of
R
values was generally moderate in the four rainfall stations, with the coefficients of variation ranging from 0.37 to 0.43 and showing no difference in variation among stations. 2) Similar to the intra-annual distribution pattern of rainfalls, there was one peak in terms of the intra-annual variation of
R
values. Specifically, monthly
R
values distributed mainly between March and August within a year, which accounted for 80.92% of the annual
R
value. The maximum and minimum monthly
R
value were observed in June and December respectively, which accounted for 23.87% and 1.86% of the annual
R
value. 3) The statistical results of M-K tests (i.e.
M
values) on
R
values were all positive (ranging from 0.31 to 0.78) in the four rainfall stations over the study period, suggesting a potential increasing trend in the probability of soil erosion in the study region. However, all
M
values were not statistically significant. 4) Annual
R
values ranged from 1 904.1 to 10 841.48 MJ·mm/(hm
2
·h·a) in the four rainfall stations, with no sinificant difference among them. The spatial distribution pattern of
R
values was similar to the spatial pattern of rainfalls in the Lianshui basin, both of which showed a gradually increasing trend from the northeast to the southwest of the basin.
[Conclusions]
In our study, a model using monthly rainfall data was applied to calculate the rainfall erosion force, and the characteristics of its spatial and temporal variation were analyzed. Our results suggested that both intra-and inter-annual variations of rainfall erosivity in the Lianshui basin were consistent with the temporal and spatial distribution of rainfalls and the precipitation patterns in the region.
2018 Vol. 16 (3): 18-25 [
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509
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26
LIU Mengling, ZHU Qiliang, LI Jiamei, ZHANG Guangcan, WANG Yanping
The arid-tolerance of trees based on the anatomical characteristics of fine roots
[Background]
The selection of tree species is critical for the soil and water conservation and vegetation restoration in arid-barren mountainous areas. There are 40% areas in Shandong province belonging to mountain area, where water is one of important environment factors limiting vegetation restoration. Thus, it is very important to choose tree species with developed roots. The examination on the anatomical characteristics of tree roots would be helpful for the tree species selection.
[Methods]
The study site is located in Xueye county of Laiwu city, belonging to typical arid-barren mountainous areas of Shandong province. After afforestation, ten common tree species were selected and all the roots of trees for each species were sampled. According to the branching orders, the roots were grouped into five classes, and root traits (i.e., the root diameter, cortex thickness, stele diameter, ratio of vascular cylinder to root diameter, vessel diameter, and vessel density) were examined by paraffin sectioning, Nikon Eclipse E200 microscopy and Scope Image 9.0 software. The differences of root anatomical traits among tree species were analyzed and clustered by One-way ANOVA and SPSS 19.0 with Excel.
[Results]
The fine root diameter of tree species increased with the root order. The first order roots showed larger diameter in conifer trees than in those deciduous trees. The diameters of deciduous shrub roots were smaller than those arbor and vines; however, the difference among species was not significant (
P
<0.05).The stele diameters of fine roots demonstrated similar changes with the average diameter of fine roots. The cortex thickness of the first and second order roots in the deciduous trees was large. However, the root vessel diameter of all the tree species increased with the increase of root order, the vessel diameters in vines roots (i.e.,
Lonicera japonica
and
Euonymus fortunei
) were smaller than those in arbors and shrubs roots. The vessel diameters in deciduous trees were larger than those of other tree species. The changes of vessel density were opposite to that of root diameter. Based on the anatomical characteristics of fine roots, the 10 species were clustered into three categories, the first one was the thin cortex and compacted transport tissue, including
L. japonica, Lespedeza bicolor, Vitex negundo
var.
heterophylla, Amorpha fruticosa
and
Pinus thunbergii
; the second one was the thin cortex and loose transport tissue, including
E. fortunei, Cotinus coggygria, Robinia pseudoacacia
and
Platycladus orientalis
; the third one was the thick cortex and loose transport tissue, including
Gleditsia sinensis
.
[Conclusions]
The anatomical structure of tree root in arid habitat is related to its life type, which is the ecological adaptability in the process of long-term tree species evolution. Root's anatomical structure is a key index to explore the survival strategy of tree species in drought stress environment.
2018 Vol. 16 (3): 26-33 [
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418
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34
CAO Xiayu, YANG Qinke, LAN Min, WANG Chunmei
BDU partition for extracting distributed soil erosion slope length in large-and medium-scale watersheds
[Background]
The strategy for partitioning DEMs into basic data units (BDU) is a key issue in the efficient extraction of watershed slope length in large-area regions.
[Methods]
This paper took the mild undulating hills of the Northeast China and the loessial hilly areas of the Loess Plateau as study regions, in each case single DEM mosaics were formed from nine standard 1:250 000 scale map sheets. The slope lengths were then extracted by BDU which were taken to be mid-sized watersheds in the standard map sheets provided with effective buffer zones to fill a rectangular map. The maps were then compared and analyzed using information from the extracted units such as statistical characteristics, efficiency and other aspects.
[Results]
1) Based on the implications and extraction algorithms of slope length for distributed watershed soil erosion, the basic data units (BDU) for watershed slope length extraction (The minimum effective watershed,
W
ME
) were the smallest basins which were distinguishable and also had clear hydro-geomorphic significance. If the workspace was much larger than the area of a
W
ME
, the connecting line of the peripheral watershed boundary of the
W
ME
(BND
WME
) was included in the rectangle. 2) Rectangular data areas (For example, standard map sheets) after reasonable extension avoided the detrimental influences that occurred from incomplete slope length zones and was used as suitable map sheets for the BDU to extract the complete set of watershed slope lengths. 3) Comparing cases in the Northeast China (Mild terrain) and the Loess Plateau (Steep hilly terrain), common extents of surrounding areas of incomplete slope length (The data buffer width) were different at 3 km and 5 km respectively.
[Conclusions]
In the extraction of slope length in large area, after suitably extending data by the buffer widths, we can then use the extended rectangular data as inputs to extract slope length directly. This work allows efficient methods that take standard map sheets or rectangular blocks as data units to be applied for general watershed slope length extraction in large-area regions.
2018 Vol. 16 (3): 34-40 [
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345
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41
LIU Shiyu, DENG Wenping, OUYANG Lei, HU Xiaodan
Contributions of precipitation and vegetation restoration to the runoff in Pengchongjian small watershed:Comparison of empirical statistics analysis method and hydrological modeling simulation method
[Background]
Quantifying the impacts of precipitation variation and vegetation restoration on runoff is essential not only for understanding the mechanism of hydrological response in watershed, but also for local water resources management as well as preventing floods and droughts. The Pengchongjian small watershed has experienced forest deforestation by local inhabitants in early 1980s. Since then, its vegetation has been restoring without human disturbances, and it is a natural site for this study. This paper aims to calculate the exact contribution rates of precipitation variation and vegetation restoration to runoff.
[Methods]
Based on observed daily precipitation and runoff data at Pengchongjian hydrological station from 1983 to 2014, we applied Mann-Kendall test and trend analysis methods to detect the inflection points of annual precipitation and runoff. Then, after dividing baseline period and changing period from 1983 to 2014, we calculated the exact contribution rates of precipitation and vegetation restoration on different time scales by using comparative methods of empirical statistics and hydrological modeling simulation.
[Results]
1) A consistent inflection point of 2003 was found both for annual precipitation and runoff. Thus taking 1983 to 2003 as baseline period, 2004 to 2014 as changing period, the linear relationship between annual precipitation and runoff in baseline period was fitted. 2) Compared to the baseline period, annual precipitation and runoff decreased by 8.7% and 29.2%, with average annual decrease of 12.7 and 22.1 mm. The average depth of runoff in Spring, in Summer and in whole year scale decreased by 100.2, 105.8 and 243.0 mm respectively. 3) The results of the empirical statistics suggested that the contribution rates of precipitation variation and vegetation restoration on runoff were 58.9%, 41.1% and 71.6%, 28.4% in Spring and in Summer respectively, while results from the hydrological model simulation were 61%, 39% and 81.6%, 18.4%. However, on annual scale, the contribution rates of precipitation variation and vegetation restoration were 57.1% and 42.9% by empirical statistics method while the rates were 70% and 30% by hydrological model simulation method.
[Conclusions]
The results of the two methods are generally similar, indicating that the results are more credible. It is also known that the results are different on different time scales, and the contribution rate of precipitation variation is greater than that of vegetation restoration. That is to say, both precipitation and vegetation influence the change of runoff, but the main driving factor of runoff change is precipitation, which determines the trend of runoff change.
2018 Vol. 16 (3): 41-49 [
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50
ZHANG Zhiling, YIN Zhigang, XIE Wei, XIA Chunyuan, WANG Dongli, WANG Xianglei, ZHAI Jingxuan
Improvement effects and evaluation of different plants on the physical properties of root region soil in a mine dump
[Background]
Land deterioration caused by mining exploitation has been highly focused all around the world. The mine soil dump is the main factor causing the ecological issues around the mine sites, such as air pollution, water pollution and soil erosion. Hence, the mine soil restoration and treatment has been considered as a great issue. This article aimed to reveal the performance of various plants in soil improvement of a mine dump.
[Methods]
To understand the improved effects of different plants on root region soil in the depth of 0 to 50 cm, three tree species (
Ulmus pumila, Robinia pseudoacacia
, and
Rhus typhina
) and three shrub species (
Amorpha fruticosa, Vitex negundo
, and
Periploca sepium
Bunge) from artificial forests and weeds were selected as research objects. The physical properties around the soil region of different plants were thoroughly evaluated by principal component analysis method.
[Results]
Field capacity of soil around the root regions of seven plant species generally increased firstly and then decreased as the soil depth increased. The field capacity at each soil layer around the root region of
R. typhina
was significantly (
P
<0.05) higher than that of other species, followed by that of
U. pumila
. The soil bulk density at each soil layer around the root region of
R. typhina
was the lowest among all species. While the soil bulk density at the soil depth of 0 to 10 cm, 20 to 30 cm around the root regions of
A. fruticosa
was the highest among all species. It was found that the soil bulk density around the root regions of tree species was lower than that of shrub species. In the soil around the root regions of seven plant species, the content of sand grain was higher than that of silt and clay grains. At the depth of 0 to 10 cm of soil near the roots of
P. sepium
, the content of silt and clay grains were greater than others. At the soil depth of 10 to 20 cm, the content of silt and clay grains around the root regions of tree species were higher than that of shrub species. And at the soil depth of 30 to 50 cm around the root region, the content of silt and clay grains decreased with the increase of soil depth. The physical properties of soil using principal component analysis showed that
R. typhina
>
U. pumila
>
R. pseudoacacia
>
P. sepium
> weeds >
V. negundo
>
A. fruticosa
.
[Conclusions]
For the reclamation of the mine dump in the studied area, trees such as
R. typhina
might be prioritized to be chosen, which not only helps to improve the forest health but also to enhance the potential for soil production. This study would provide reference for soil improvement effects of different plants on the root region soil of mine dump, and provide evidence for the vegetation restoration and reconstruction of the dump.
2018 Vol. 16 (3): 50-58 [
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433
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59
YANG Yuqiong, DAI Quanhou, LI Changlan, PENG Xudong, YAN Youjin
Characteristics of nitrogen and phosphorus underground loss in karst slope farmlands under simulated rainfall
[Background]
As a unique landscape, karst slope is characterized by a "double-layer hydrologic structure" consisting of surface and underground. The karst slope farmland with such special structure leads to serious soil and water loss in two types, surface loss and underground leakage loss. The serious water and soil and nutrient loss not only did cause land productivity reduction and ecological deterioration, but result in underground water pollution. The soil nutrient loss process on the karst slope farmlands is complicate, which is affected by many factors (e.g., precipitation, topography and soil properties).There is no doubt that rainfall intensity and underground pore fissure are the two of the most important factors influencing water and soil loss on karst slopes.
[Methods]
Taking karst slope farmlands as the research object, several rainfall simulation tests were conducted. In addition, a steel tank (length of 4.0 m, width of 1.5 m and depth of 0.35 m), in which the underground pore fissure degree could be adjusted, was used to stimulate the surface micro topography and underground fissure structure of karst slopes. The first step was to adjust the slope degree and underground fissure degree of the steel tank to the designed levels. The second step was to carry out artificial rainfalls and collect the runoff and sediment samples at 10 minutes interval. The final step was to determine the total nitrogen and total phosphorus concentration of samples collected.
[Results]
1) The underground runoff was positively correlated with the rainfall intensity and the underground pore fissure degree. 2) Rainfall intensity showed certain effects on nutrients concentration in underground runoff, in which the total phosphorus concentration showed a wavy change with the increase of rainfall intensity while the total nitrogen concentration increased with the increasing of rainfall intensity. Underground pore fissure degree had a significant effect on the total nitrogen concentration and the correlation coefficient was 0.906, but had no obvious effect on the total phosphorus. 3) The amount of total phosphorus loss was fitted by a linearly equation with the rainfall intensity, and fitted by a polynomial with the underground pore fissure degree. 4) The cumulative runoff was significantly related to the cumulative loss of total nitrogen and total phosphorus in the underground runoff, and the correlation coefficient was 0.986 3 and 0.997 4 respectively.
[Conclusions]
In summary, the underground pore fissure degree has little effect on soil nutrient loss, however the rainfall intensity is a key factor influencing soil nutrient loss on karst slope farmlands. These results of this study may provide a theoretical basis for solving the effect of soil and nutrient loss on social economy, ecological environment and human life development.
2018 Vol. 16 (3): 59-67 [
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582
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473
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68
LI Haiyan, DING Jianhong, BAI Yong, WU Hao, ZHANG Feng
Promotion effects of comprehensive control technologies of soil and water conservation in Karst region:A case study of the Guanmaidi Watershed and the Gaojiancao Watershed
[Background]
There are some key problems such as seasonal drought and water shortage poor soil loss, low agricultural productivity, low economic level in Karst regions. In this paper, taking the Guanmaidi Watersheds of Zhanyi county and the Gaojiancao Watersheds of Malong county in Qujing city of Yunnan province as an example, the research group popularized techniques of controlling the above problems and studied their benefits.
[Methods]
With reference to index value and weight, the research group investigated six indexes including pre-persuading of the core area, farmer participation, the satisfaction of the beneficiary, willingness of non-beneficiary, cost of investment, and return. The first four indexes were scored by the members of the project group, the supplier technical constructors, project liaison of the local water bureau, the beneficiary and non-beneficiary, and the cost and return were scored in accordance with the actual situation. The research group evaluated application benefit of techniques with facilities installation through weighting average score of above indexes. The benefits of the demonstration of planting
Pennisetum giganteum
z. x. lin and soil improvement were evaluated though setting up field controlled experiment, observing and comparing indexes such as leaf, plant height, yield, root biomass, soil moisture and soil chemical composition
[Results]
1) The benefits evaluation of optimal allocation technology of water technologies were in the order as:Photovoltaic pumping (7.8) > modular water tank (6.9) > flexible water cellar (6.15), and the area of irrigation benefit reached 63 hm
2
after applying optimal allocation technology of water technologies. 2) The benefits evaluation of highly efficient utilization technology were in the order as:Drip irrigation (7.65) > plastic mulching with degradation membrane (6.3) > irrigation with drip bag (5.4) > infiltration irrigation with low-cost device (5.2), and the efficiency of water utilization increased by 30% after applying highly efficient utilization technology. 3) After soil improvement,the plants of corn and
P. giganteum
z. x. lin were bigger, the yield of corn increased by 8.82%, the yield of
P. giganteum
z. x. lin increased by 17%, the chemical composition of the soil increased by 6.54%-22.87%. 4) Compared the planting of corn with the planting of
P. giganteum
z. x. lin, the root of
P. giganteum
z. x. lin were intricate and massive, the root weight was 6 times higher and the soil water content was 48% higher. Feeding cattle using the plant of
P. giganteum
z. x. lin increased economic income by 240 000 RMB Yuan per ha comparing with corn.
[Conclusions]
These promotions of technologies mentioned above had obtained favorable effects, and comprehensively harnessing the existing problems in karst areas, which can be used as reference for the comprehensive management decision of soil and water conservation in the region and the application of technology in similar region.
2018 Vol. 16 (3): 68-78 [
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564
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79
CAO Gongxiang, WANG Yunni, WANG Yanhui, XU Lihong, JI Meng
Effects of thinning intensity on throughfall and stemflow of
Larix principis-ruprecitii
plantations
[Background]
Quantifying the effects of different forest thinning intensities and stand structure on the partitioning of rainfall aims at providing scientific evidences in the forest management based on hydrology.
[Methods]
The designed experiment included 5 plots with the same slope orientation in a small catchment named Xiangshuihe of Liupan Mountains, Ningxia. All of the plots, with equal areas of 30 m×30 m, were on a slope and were laid out in a homogeneous
Larix principis-ruprecitii
plantation. One plot was not thinned and the other plots were thinned at four different intensities:14.1%, 37.4%, 43.0% and 53.4%, respectively. Twenty throughfall collectors (diameter 20 cm) for each plot were mechanically arranged and the throughfall under canopy in each rainfall event was collected from May to October 2012. Stemflow was also measured in each rainfall event in the growing season of 2012. In each treatment, 2 diameter classes were defined after thinning, and one representative sample tree per diameter class was selected for each. The bark on each sample tree was scraped off to smooth the surface in preparation for the fitting of a plastic collar. After the plastic collars were attached, plastic tubes were inserted into small holes located in the lowest part of the collars to collect the water in containers. The throughfall and stem-flow, was measured 17 times during the experiment time. Differences in the accumulated values of throughfall and stemflow among the treatments were analyzed with ANOVA.
[Results]
During the experiment period, the bulk rainfall was 507.2 mm, and the throughfall of
L. principis-ruprecitii
plantation in the control accounted 56.6% of total precipitation; whereas throughfall increased significantly with the increase of thinning intensity, and was 62.1%, 60.9%, 68.6% and 74.5% of the bulk rainfall, respectively corresponding to the thinning intensity of 14.1%, 37.4%, 43.0% and 53.4%. Stemflow decreased significantly with the increase of thinning intensity, and was 0.91%, 0.73%, 0.54%, 0.37% and 0.36% of the bulk rainfall, respectively corresponding to the thinning intensity of 14.1%, 37.4%, 43.0% and 53.4%. The canopy interception decreased 5.3%, 4.0%, 11.5% and 17.3%, respectively while compared with the control. Total throughfall was negatively and linearly correlated to the leaf area index, forest coverage, basal area, and tree density. In contrast, throughfall was modelled by considering these variables together with bulk rainfall in a multiple exponential expression(
T
=
Re
aX
), which simulated the throughfall with
R
2
=0.95.
[Conclusions]
The results and prediction accuracy of the model may offer scientific basis for forest management based on hydrological basis. When the
L. principis-ruprecitii
was about 30 a, the thinning intensities was 43.0%-53.4% (Stand density:844-1 300 Trees/hm
2
) was the optimal range for increasing the throughfall in Liupan Mountains. Such ideal stand structure will be conducive to realizing the multiple goals,including the stable stand structure and regional water safety.
2018 Vol. 16 (3): 79-85 [
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86
YAN Ming, HE Li, WANG Suiji, ZHENG Mingguo, SUN Liying, XU Jiongxin
Changing trends of NDVI in the Yellow River basin from 1982 to 2012 at different temporal scales
[Background]
Climate change and human activity lead to vegetation cover obviously changed in the Yellow River basin. Thus, it is necessary to study the temporal and spatial variation of vegetation change from multiple time scales. This paper aims to understand which one of trends with different time scales may represent the changing trend of vegetation in Yellow River basin.
[Methods]
Two processed datasets of NDVIs, GIMMS and MODIS in Huayuankou Hydrologic Station were used for this study, because the lower reaches of the Yellow River after Huayuankou has a small area and mainly are cultivated land, the data in Huayuankou Hydrologic Station should enough represent NDVI changes in the Yellow River basin. Firstly, linear fitting was applied to calibrate the spatial distributions of NDVI in the Yellow River basin at different temporal scales. Then, Mann-Kendall trend analyzing method was adopted to detect the trends of NDVI with different time scales. Finally, matrix was used to analyze the correlations of NDVI trends between different temporal scales.
[Results]
1) The general spatial distribution characteristics of NDVI was low in the northwest and high in the southeast of the Yellow River basin, and NDVI increased gradually from northwest to southeast. The spatial distributions of NDVI in summer and autumn were similar, as well as the same in winter and spring. 2) More than half area with increasing trend of NDVI was detected on yearly scale in the Yellow River basin from 1982 to 2012. As for seasonal scale, some areas had increasing trend of NDVI in winter and spring, while less area had increasing tread of NDVIs in summer and autumn. Area with increasing trend in March and October was more than in other months. 3) The performance of annual trend was combination of multiple months, while the performance of seasonal trend was contributed by single month. Increasing trend of NDVI in winter was mainly contributed by increased vegetation cover in February, but increased vegetation cover in October failed to make an obviously increasing trend of NDVI in autumn.
[Conclusions]
The change of vegetation cover has obvious differentiation at different time scales in the Yellow River basin. The increasing trend of NDVI with yearly scale is not necessary available for all the seasons, and months with increasing trend of NDVI are mainly March and October. In total, the results of NDVI trend analysis in annual scale do not fully represent trends of other time scales. Not only the trend of yearly scale, but also the seasonal scale and monthly scale should be calculated and verified for analyzing the trend of NDVI with yearly scale.
2018 Vol. 16 (3): 86-94 [
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95
ZHANG Dong, ZHANG Hongjiang, MA Lan, SUN Yihui, GUO Kaili, CHENG Qiang
Assessment of river naturalness based on grey relational analysis and analytic hierarchy process:A case study of Chaohe River
[Background]
Riparian ecosystem functions play important roles in human society and economic development. An objective and systematic assessment method can provide theoretical support for the restoration and protection of riparian ecosystem. In this paper, the Chaohe River (river reach from Gubeikou Bridge to Xinzhuang Bridge) was taken as a case to study the method of river naturalness assessment based on the concept of "near-natural".
[Methods]
According to the natural quality and social service attributes of the Chaohe River, the river was divided into different sections. The 24 indicators were contained in the river naturalness assessment system, which involved 5 aspects including hydrological elements, river form, physical and chemical properties of water quality, riparian zone status, and the furaction of landscape and recreation. The investigation method of assessment indicators has been studied by reference to the "near-natural assessment system of stream". According to the judgment criteria of each indicator, the normalization processing was carried on according to the natural state, the near natural state, the degraded state and the artificial state. The weight of each indicator in the assessment system was calculated by the Analytic Hierarchy Process (AHP). Taken the measured value of the index as the reference series, referring to the criterion as the comparison sequence, the gray correlation degree was calculated by the point to range distance. The maximum degree of relevance covresponding to the natural level was the final evaluation result.
[Results]
The assessment results indicated that in the light of natural evolution and human activity interference, there were two river sections in artificial state, nine river sections in degraded state, four river sections in near natural state, and one section in natural state. On the basis of this assessment results, 1.2 km of the river sections were in artificial state, 12.58 km of the river sections were in degradation state, 6.6 km of the river sections were in near-natural state and 0.62 km of the river sections were in natural state which were about 6%, 60%, 31% and 3% of total length, respectively.
[Conclusions]
In general, although most of the survey sections of Chaohe River were in the state of degradation, there were still potential conditions for near natural restoration in the long run. It may promote river to a higher natural level to complete the river restoration based on river ecosystem assessment results and taking advantage of combination of natural ways and artificial management. Furthermore, evaluation index system has a high systematicness, the calculation was simplified and the indicators have an obvious impact on the result by the method of natural assessment of rivers based on AHP and Grey Relational Analysis(GRA).
2018 Vol. 16 (3): 95-102 [
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103
MA Liang, WANG Xiaojun, WU Enjiang, XING Jinlong, JIANG Guanghui
Protective exploitation and evaluation of a typical strong seepage zone in Jinan, the city of springs
[Background]
Xinglong is a typical strong seepage recharge zone with the nearest and largest trait from the four spring groups named Baotu Spring, Black Tiger Spring, Five Dragon Pool and Pearl Spring in Jinan city. In the process of urbanization, some partial region of Xinglong area gradually transit from nearly natural type to strong cover leakage zone. Its strong leakage recharge function or supply of spring water gradually reduced.
[Methods]
1) With the aid of remote sensing, geographic information systems and other technical means, as well as site investigation, the information of geology, meteorology, hydrology, soil, vegetation and settlements were collected and sorted out in the studied area. A database of natural and socioeconomic data was established. 2) By taking on-the-spot geophysical (5 electrical sounding profiles, 32 physical points), drilling (165 holes, total footage 83.07 m), seepage pressure test (4 layers 4 times water seepage test, 3 layers 3 times water pressure test), drilling core observation (4 groups of drilling core, respectively 11, 15, 19 and 10, a total of 55) and other methods, the hydro-geological parameters of the strong seepage zone were obtained. 3) Combined with the groundwater hydrodynamic theory, the Xinglong groundwater infiltration-seepage numerical model was constructed. According to the land use, the hardening rate and other indicators under different development scenarios, as well as the geological, geomorphological and hydrogeological conditions of the studied area, the computational partitions were divided into three types, including Commercial District (N), Residential District (F) and Park District (E). On this basis, the groundwater recharge analysis and simulation were conducted to find out the changing rules of groundwater recharge in Xinglong Strong Seepage Zone. 4) Based on the strategies of strong seepage zone protection and low impact development, the protective development measures for the Xinglong Strong Seepage Zone were put forward.
[Results]
The research showed that the increase of surface runoff per square kilometer after construction was about 65 000 m
3
/a, an increase of 36.29%, and the infiltration recharge reduced by about 88 000 m
3
under the situation that original planning scenario A considered less protection and low-impact development(LID), a decrease of 46.86%. With full consideration of protection and LID and adjustment, i.e., scenario B, the reduction of surface runoff by about 16.17% over the scenario A and the increase of infiltration and recharge by about 41.20% resulted in a significant protection effect. However, compared with the near-natural state, infiltration recharge only recovered to 75% of the original level. In the scenario C, by more actions such as delimiting the scope of protected areas, the construction of ecologically clean small watersheds, ditch protection and treatment, restoration of damaged mountains, ecological transformation of old villages, and inter-basin water diversion, the infiltration recharge functions of the Xinglong Strong Seepage Zone can be improved to 129.85% of the status quo according to modeling.
[Conclusions]
It can be seen that the development and construction have strongly changed the original properties of the underlying surface and damaged the groundwater recharge function in the strong seepage zone. Even if the low-impact development is adopted, the groundwater recharge due to the project construction will not be completely eliminated. More actions as described in scenario C are needed, and it has become the most desired and effective scheme at present.
2018 Vol. 16 (3): 103-111 [
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112
GUO Qiaoling, SU Ning, DING Bin, YANG Yunsong
Characteristics of preferential flow in the soil cracks of a coal mining subsidence area
[Background]
Shenfu-Dongsheng coalfield is located in arid and semi-arid area, and its ecological environment is fragile. Large amount of coal mining results in widespread distribution of surface cracks in subsidence area. The occurrence of fissures provides preferential way for water migration, and causes soil and water loss and a series of ecological environmental problems. Studying the preferential flow in the cracks of coal mining subsidence area may provide basic support for controlling soil and water loss and protecting ecological environment.
[Methods]
The subsidence area without any vegetation in Shenfu-Dongsheng coalfield has been taken as research area. Two test points (1 crack of 20 mm in testing point 1 and 3 cracks of 5 mm in testing point 2) were set in a 50 m×50 m testing area, then 4 g/L bright-blue solution was used to dye it, and images were taken in 1 horizontal and 5 vertical sections, as well as soil samples were collected from each section. Then the images were processed and calibrated by Photoshop CS 6.0 and ArcGIS 10.2. Physical and moisture characteristics of the sampled soil from the testing area were analyzed, including grain composition, soil porosity, water content, bulk density, saturated hydraulic conductivity, and field water-holding capacity.
[Results]
1) Under different surface cracks, the soil porosity, water content and field water-holding capacity increased and the saturated hydraulic conductivity decreased with the increase of soil depth. Moreover, they were almost the same in the same soil depth even in different crack condition. 2)On the horizontal section, the dyeing area of the soil decreased with the increase of depth, and the location of the dyeing region had a certain continuity. 3)On the vertical profile, the soil dyeing area had S shape decreasing trend with the depth increasing. The maximum dyeing depth was 66.02 cm in test point 1 and 46.87 cm in test point 2. At the same time, the distribution characteristics of preferential flow were significantly different in two test sites. In addition, the distribution characteristics of preferential flow in the two test sites were also different, indicating that the width and number of cracks affected the preferential flow. The area with larger crack width had great influence on the seepage flow, and preferential flow reached the deeper part of the soil. 4)Dyeing paths were more below ground 8-54 cm in test point 1 while 12-28 cm in test point 2. In general, the number of wide dyed paths decreased and the number of small dyed paths increased with the increase of soil depth.
[Conclusions]
In summary, the surface cracks in coal mining subsidence area cause the occurrence of preferential flow. The width and number of cracks have a significant influence on the preferential flow in the coal mining subsidence area.
2018 Vol. 16 (3): 112-120 [
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121
KANG Qing, HUANG Jun, JIN Pingwei
Study on the evaluated index and method of the soil conservation benefit for the soil and water conservation engineering
[Background]
The soil conservation benefit (SCB) is the base of benefit evaluation for the soil and water conservation engineering (SWCE). Currently, the mainstream approach has several disadvantages, such as large amount investment, over-reliance on field facilities and equipment, difficult to obtain the dynamic and long-term result. It is necessary to improve and consummate the current method of calculating SCB for the SWCE.
[Methods]
This paper summarized the merits and demerits of current evaluated indexes and methods. Based on the American universal soil loss equation (USLE), this paper proposed a new core index of soil erosion decrease ratio (SEDR) and its calculating procedure. The core index of SEDR included 6 factors:rainfall erosivity (
R
), soil erodibility (
K
), slope length (
L
), slope gradient (
S
), vegetation cover management (
C
) and support practice (
P
) factor, which are independent variables in USLE.
[Results]
The SEDR could be calculated in the following steps:1) obtaining the high resolution image (HIR) and the digital elevation model (DEM) data by the remote sensing satellite or the unmanned aerial vehicle, before and after the governance project carried out; 2) preprocessing the high resolution remote sensing images (atmospheric correction, radiometric correction, etc.); 3) using eCognition Developer software and the object-oriented method, the land use was classified, the measured patch vector file of soil and water conservation were generated, for calculating SEDR using patch as unit in the later stage; 4) extracting and calculating the value of
R, K, S, L, C
and
P
factors, and generating their raster maps, using ENVI and ArcGis software, based on the HIR, DEM, weather data and soil files of the studied area; 5) calculating the SEDR value for each patch based on the patch vector file and the raster maps of above 6 factors; 6) calculating the comprehensive value of SEDR for the studied area by the measured patch area-weighted method based on the SEDR of each patch; 7) calculating the dynamic and long-term SEDR value to reflect the SCB of the SWCE, using the different spatial and temporal scale input data.
[Conclusions]
This paper improved the previous method of calculating SCB, and proposed a new index of SEDR and its calculation procedure. The above study can supply the important technical support for the development, management and benefit evaluation for the soil and water conservation engineering.
2018 Vol. 16 (3): 121-124 [
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125
LI Jiazhu, HUANG Zhanbin, BAO Fang, CHEN Wei
Comprehensive assessment on soil moisture and nutrient conservation of environment functional materials
[Background]
Water deficit and poor fertilizer in soil are very serious in northwestern arid and semi-arid area of China. Meanwhile, water and fertilizer conversation ability of soil is always limited on agricultural development and environmental management in these regions. To search proper additive materials as synergist to improve soil capacity of absorbing and conserving water is an efficient way. Thus, environment functional material is a suitable kind of material with good function, environmental harmonization and economic efficiency. The wide application of environment functional materials provides new method to water and nitrogen conversation in agriculture and environmental harness. With more and more new environment functional materials being developed constantly, a critical problem needs handling is how to evaluate the effects quantitatively of the materials with various composition and proportion. But no relative effective method has been reported yet.
[Methods]
In present study, a kind of composite material was chosen as the additive material with three kinds of environment function materials, which were super absorbent polymer(SAP), zeolite and humid acid. The soil-column leaching was used experimentally for the effect of the composite material on water-conserving capacity. Ten treatments were formed by different kinds of proportion with each material in three amount levels, including a control treatment as CK with no material added. With four times leaching, the conversation amounts of water and nitrogen were measured after each leaching. Based on the results of soil-column leaching experiment, an analytical hierarchy process-fuzzy comprehensive evaluation (AHP-FCE) method was introduced to assess the effectiveness of water and nitrogen conservation. Moreover, the economic efficiency of the materials, which was rarely involved in relative studies, was evaluated with AHP-FCE method in this study.
[Results]
When the application amount of the compound material on unit area was the same, the effect of water conservation was the best when the ratio between the three environmental functional materials SAP, zeolite and humid acid was 2:20:1. When the proportion ratios of the three materials were 1:100:10, 1:20:0.2 and 1:2:1, the effects were the best for ammonia nitrogen, nitrate nitrogen and urea nitrogen conservation, respectively. When the proportion ratio of the three materials was 1:10:1, the compound material had the best economic efficiency. The comprehensive effect of the compound material was the best when the proportion ratio of the three materials was 1:10:1. Compared with the control treatment (CK) in the experiment, the best conversation effects of water, ammonia nitrogen, nitrate nitrogen and urea nitrogen were 1.22, 1.20, 4.19 and 1.19 times of the CK, respectively. The best proportion selection also performed favorable economic efficiency as well.
[Conclusions]
This study proves the reliability of the comprehensive assessment method for multi-function environmental materials. The AHP-FCE method can avoid the randomness caused by subjective deviation, and the disadvantage of uncertainty of fuzzy evaluation, therefore, the AHP-FCE method can be used effectively in comprehensive evaluation and selection of environment functional materials.
2018 Vol. 16 (3): 125-133 [
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134
WANG Yuhang, YU Qiang, YUE Depeng, ZHANG Qibin, MA Huan
Landscape pattern simulation within a county based on GD_SVM_CA-Markov model
[Background]
Dengkou county is a typical arid and semi-arid area with obviously serious desertification. Ecological environment protection and treatment needs to be solved urgently. In the process of urbanization, balancing the three types of land for construction land, sandy land and ecological land is particularly important. Based on the GD_SVM_CA-Markov model, this paper aims to analyze the change of the dynamic distribution of the landscape in Dengkou county from two dimensions of time and space, to explore its change pattern, and carry on the simulation prediction, so as to provide a certain decision-making reference for the local urban development planning, the desertification control and the ecological environment protection.
[Methods]
Based on 10 driving factors (DEM, slope, aspect, NDVI, groundwater depth, evapotranspiration, population density, the nearest distance to water area, the nearest distance to settlement, the nearest distance to road), the land use suitability atlas was created by using GeoDetector to explore the relationship between land use change and 10 driving factors and MCE module provided by IDRISI software; Through SVM to define the transformation rules of the cell, thus the improvement of CA model was achieved; Based on the land use data of the two periods of 2006 and 2011, the Markov model was used to generate the land use transfer matrix. The landscape pattern simulation of study area in 2016 based on the GD_SVM_CA-Markov model was implemented with the above process integrated. In order to test the simulation accuracy, the Kappa coefficient was used for the test
[Results]
From 2006 to 2016, the landscape area of construction land in Dengkou county increased from 5 785.55 hm
2
to 8 952.67 hm
2
, the landscape area of sandy land decreased from 76 616.15 hm
2
to 56 460.50 hm
2
, the landscape area of water area increased from 23 859.88 hm
2
to 24 679.10 hm
2
, the landscape area of woodland and grassland increased from 117 452.37 hm
2
to 128 120.87 hm
2
. For construction land, there was 15.64% probability of conversion to arable land. In the case of water area, there was 11.56% probability of turning into arable land. In terms of sandy land, there was 18.37% probability of turning into woodland and grassland. The influence degree of the 10 driving factors on the landscape type change in Dengkou county was 0.248 816, 0.048 784, 0.134 342, 0.951 212, 0.975 924, 0.873 667, 0.520 317, 0.256 226, 0.413 550, 0.178 658 respectively according to the above order. The Kappa coefficient of the CA-Markov model simulation results of 2016 was 0.862 8, the Kappa coefficient of the GD_SVM_CA-Markov model simulation result of 2016 was 0.925 0. Based on the land use data of 2016 and the land use transfer data of 2011-2016, the GD_SVM_CA-Markov model was used to simulate and predict the spatial distribution pattern of landscape in 2021. During 2016-2021, the landscape area of construction land increased from 8 952.67 hm
2
to 11 610.21 hm
2
, the landscape area of sandy land increased from 56 460.50 hm
2
to 67 235.11 hm
2
, and the landscape area of ecological land such as water area and woodland and grassland decreased from 152 799.97 hm
2
to 143 670.04 hm
2
.
[Conclusions]
Hydrological conditions, vegetation cover and population factor are the decisive factors that determine the temporal and spatial changes of local landscape types. Thus, at the same time as urban development, it is necessary to pay attention to ecological and environmental protection. The simulation result of 2016 based on GD_SVM_CA-Markov model has higher overall simulation accuracy and is better than the simulation result of 2016 based on CA-Markov model. Therefore, it is feasible to use GD_SVM_CA-Markov model to simulate and predict the spatial distribution pattern of landscape in Dengkou county.
2018 Vol. 16 (3): 134-141 [
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142
ZHOU Libo
Historical venation of researches on soil quality in China
[Background]
Soil quality is a critical tool to measure sustainability and also the important path to solve food and environment problems in developing countries. As a largest developing country, having a further discussion on the historical venation of soil quality is of great importance for reference. Whereas, there are obvious disadvantages of traditional literature review method, for example, subjective judgement. Hence, the bibliometrics method, running by the software of Citespace, was used here to identify the venation of soil quality in China. Based on the data in CNKI, there has been a great emerging in research articles on soil quality in China, just for the period of 2006-2016, the number of papers accounts for about 84.5% of total since 1980. However, previous reviews cannot completely reflect the historical venation because of their limitations, for exalaple, it is impossible for a scholar to read all of papers in this field and exactly and correctly identify the principle publications.
[Methods]
Based on the CNKI (China National Knowledge Infrastructure) database, visualization analysis based on Citespace and combined with critical reading of literatures was used to quantitatively analyze the historical advances of soil quality research in China since 1980s.
[Results]
At present, researches on soil quality in China are driven by disciplinary development and social demands are still at the basic stage where it associated much with natural science and few with social sciences. In respect of support funds, national fund is the primary source, and fund from local and Chinese Academy of Sciences takes the second place. According to the characteristics of keyword co-appearance networks at different periods, researches on soil quality in China can be divided into 4 stages with their own distinctive features:1980-1990 (Budding stage) while the main focuses were agricultural production and the relation was weak between multi-disciplines; 1991-2000 (Concept formation stage) while concept and indicators of soil quality had a further development; 2001-2005 (Initial applied stage) while scientists paid great attentions to the indicator selection and the effect of land use change, soil contamination on soil quality; and 2006-2016 (Systematized stage) while cross-disciplines become strong and more aspects about soil quality were in systematic study.
[Conclusions]
Based on such a quantitative method, the historical venation of soil quality was discussed in a relatively objective way and this will give a good reference to the future development of this research field.
2018 Vol. 16 (3): 142-152 [
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