Impacts of Land Use on Surface Water Quality in a Subtropical River Basin: A Case Study of the Dongjiang River Basin, Southeastern China
<p>(<b>a</b>) The topography and the locations of the Dongjiang River basin and sampling sites; (<b>b</b>) Schematic of upstream catchment delineation on the basis of the positions of the sampling sites.</p> "> Figure 2
<p>Dendrogram based on the hierarchical clustering analysis according to the Ward linkage method using Euclidean distance, showing the different clusters from the 83 sampling sites (S01–S83).</p> "> Figure 3
<p>Spatial distribution of sampling site groups and land use types in the Dongjiang River basin. The sites were divided into three groups corresponding to forest-dominated sites (FDS), agriculture-dominated sites (ADS) and urban-dominated sites (UDS).</p> "> Figure 4
<p>Mean ± standard error values for the water quality parameters among forest-dominated sites (FDS), agriculture-dominated sites (ADS) and urban-dominated sites (UDS) in the dry and rainy seasons. The variance results of the <span class="html-italic">post hoc</span> tests among the three groups are indicated by the letters, and significant differences (<span class="html-italic">p</span> < 0.05) are indicated by different letters (a–c).</p> "> Figure 5
<p>Tri-plot results of redundancy analysis: water quality parameters and land use variables in the dry season (<b>a</b>) and in the rainy season (<b>b</b>). Different symbol represent different site groups (forest-dominated sites: ○; agriculture-dominated sites: +; urban-dominated sites: ●).</p> ">
Abstract
:1. Introduction
2. Materials and Methods
2.1. Study Area
2.2. Sample Collection and Parameter Measurement
2.3. Spatial Analyses
2.4. Statistical Analysis
3. Results
3.1. Land Use Site Grouping and Their Distribution
Spatial scale | Forest (%) | Agriculture (%) | Urban (%) | Other (%) |
---|---|---|---|---|
Total watershed | 74.19 | 15.61 | 9.47 | 0.74 |
Catchments of 83 sites | ||||
Min | 1.62 | 3.40 | 0.00 | 0.00 |
Max | 94.93 | 79.49 | 86.62 | 16.25 |
Mean | 52.59 | 27.48 | 18.92 | 1.01 |
Median | 56.15 | 24.52 | 3.21 | 0.14 |
S.D. | 33.28 | 19.74 | 26.46 | 2.16 |
3.2. Temporal and Spatial Variations of Water Quality among the Site Groups
Landscape Factors | FDS (n = 34) | ADS (n = 28) | UDS (n = 21) |
---|---|---|---|
Percentage of Land Use (%) | - | - | |
Pforest | 86.34 ± 5.86 | 41.87 ± 19.13 | 12.25 ± 13.62 |
Pagriculture | 11.37 ± 5.10 | 47.76 ± 17.36 | 26.51 ± 11.37 |
Purban | 1.42 ± 2.15 | 8.60 ± 7.90 | 61.01 ± 15.79 |
Pother | 0.88 ± 1.44 | 1.77 ± 3.21 | 0.22 ± 0.64 |
Mainly Land use | forested land | agricultural land | urban land |
Catchment Elevation (m) | 362 ± 125 | 266 ± 104 | 108 ± 108 |
Main Topography | hilly mountains | low hills | alluvial plains |
Water Quality Parameters (Units) | N | Dry Season | Rainy Season | Kruskal-Wallis | Standard for Grade III a | Exceeding Rate (%) b | ||
---|---|---|---|---|---|---|---|---|
Mean ± S.D. | Mean ± S.D. | H | p-value | Dry | Rainy | |||
TEM (°C) | 83 | 17.73 ± 3.41 | 29.07 ± 2.11 | 123.77 | 0.000 ** | - | - | - |
DO (mg·L−1) | 83 | 6.85 ± 2.19 | 4.41 ± 1.47 | 50.07 | 0.000 ** | ≥5.0 | 20.48 | 55.42 |
EC (μs·cm−1) | 83 | 218.47 ± 239.04 | 107.59 ± 76.32 | 16.51 | 0.000 ** | - | - | - |
CODMn (mg·L−1) | 83 | 3.61 ± 2.17 | 3.63 ± 1.70 | 0.38 | 0.538 | ≤6.0 | 16.87 | 14.46 |
TP (mg·L−1) | 83 | 0.28 ± 0.38 | 0.13 ± 0.13 | 6.54 | 0.011 * | ≤0.2 | 36.14 | 21.69 |
TN (mg·L−1) | 83 | 4.07 ± 4.70 | 3.95 ± 4.40 | 0.05 | 0.83 | |||
NH3-N (mg·L−1) | 83 | 2.31 ± 4.13 | 2.37 ± 4.13 | 0.03 | 0.868 | ≤1.0 | 43.37 | 43.37 |
NO3-N (mg·L−1) | 83 | 1.73 ± 1.60 | 1.57 ± 1.31 | 0.29 | 0.593 | - | - | - |
Chl-a (μg·L−1) | 83 | 10.42 ± 9.01 | 13.31 ± 15.59 | 0.9 | 0.343 | - | - | - |
3.3. The Relationship between Land Use and Water Quality
Axes and Variables | Dry Season | Rainy Season | |||||
---|---|---|---|---|---|---|---|
Explained Variation (%) | pseudo-F | p value | Explained Variation (%) | pseudo-F | p value | ||
Canonical axes | |||||||
First axis | 30.3 | 34.4 | 0.002 ** | 27.5 | 29.9 | 0.002** | |
Second axis | 2.5 | 2.9 | 0.126 | 1.9 | 2.1 | 0.29 | |
all axes | 33.2 | 13.1 | 0.002 ** | 29.5 | 11.0 | 0.002** | |
Explanatory variables | |||||||
Pforest | 25.0 | 27.0 | 0.002 ** | 24.6 | 26.4 | 0.002** | |
Purban | 28.9 | 32.9 | 0.002 ** | 23.5 | 24.9 | 0.002** | |
Pagriculture | 3.4 | 2.8 | 0.078 | 5.8 | 5.0 | 0.01* |
Water Quality | Pforest | Pagriculture | Purban | |||
---|---|---|---|---|---|---|
Dry Season | Rainy Season | Dry Season | Rainy Season | Dry Season | Rainy Season | |
DO | 0.57 ** | 0.62 ** | −0.26 * | −0.28 ** | −0.65 ** | −0.61 ** |
TEM | −0.40 ** | −0.54 ** | 0.42 ** | 0.25 * | 0.43 ** | 0.59 ** |
EC | −0.71 ** | −0.65 ** | 0.36 ** | 0.28 * | 0.77 ** | 0.66 ** |
CODMn | −0.16 | −0.48 ** | 0.06 | 0.22 | 0.11 | 0.53 ** |
TP | −0.32 ** | −0.20 | 0.18 | 0.00 | 0.33 ** | 0.27 * |
TN | −0.53 ** | −0.35 ** | 0.17 | 0.12 | 0.58 ** | 0.40 ** |
NH3-N | −0.56 ** | −0.48 ** | 0.26 * | 0.16 | 0.56 ** | 0.53 ** |
NO3-N | −0.30 ** | 0.23 * | 0.06 | −0.10 | 0.37 ** | −0.17 |
Chl- a | −0.29 ** | −0.50 ** | 0.25 * | 0.37 ** | 0.31 ** | 0.46 ** |
4. Discussion
4.1. Impacts of Different Land Uses on Water Quality
4.2. Seasonal Differences in Impacts of Land Use on Water Quality
4.3. Management Implication for the Dongjiang River Basin
5. Conclusions for the Restoration of the Dongjiang River
Supplementary Files
Supplementary File 1Acknowledgments
Author Contributions
Conflicts of Interest
References
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Ding, J.; Jiang, Y.; Fu, L.; Liu, Q.; Peng, Q.; Kang, M. Impacts of Land Use on Surface Water Quality in a Subtropical River Basin: A Case Study of the Dongjiang River Basin, Southeastern China. Water 2015, 7, 4427-4445. https://doi.org/10.3390/w7084427
Ding J, Jiang Y, Fu L, Liu Q, Peng Q, Kang M. Impacts of Land Use on Surface Water Quality in a Subtropical River Basin: A Case Study of the Dongjiang River Basin, Southeastern China. Water. 2015; 7(8):4427-4445. https://doi.org/10.3390/w7084427
Chicago/Turabian StyleDing, Jiao, Yuan Jiang, Lan Fu, Qi Liu, Qiuzhi Peng, and Muyi Kang. 2015. "Impacts of Land Use on Surface Water Quality in a Subtropical River Basin: A Case Study of the Dongjiang River Basin, Southeastern China" Water 7, no. 8: 4427-4445. https://doi.org/10.3390/w7084427