1. Watershed classification in Taizi
River
孔维静
Chinese Research Academy of
Environmental Sciences

2. Outline
• 1. Natural, geographical and freshwater
ecosystem features in Taizi river watershed
• 2. Why classification
• 3. Method
• 4. Results

3. 1.1Overview
40° 29′ -41°40′N
122 ° 25 ′-124 ° 55 ′E
Temperate continental monsoon climate
Area: 12,000KM2
Province: Liaoning

4. 1.2 Environment variables for Taizi river watershed
Geomorphology Soil type
DEM
Annual average temperature Annual average rainfall Vegetation

5. 1.3 Environmental variables and its ecological importance
Environment Rationale
variables
Temperature Determines the spatial pattern of species distribution
Precipitation Related to watershed water cycle and water resource distribution,
determining species distribution, ecosystem process and dynamics
DEM Related to temperature, rainfall and hydrology, influencing species
distribution, freshwater ecosystem type, spatial pattern and ecosystem
process
Soil Related to water cycle, influencing hydrological process, biogeochemical
process and freshwater ecosystem structure and function
Vegetation Offering habitat for freshwater organisms, related to water temperature
adjustment, sunlight penetration, soil erosion and biogeochemical process;
influencing freshwater ecosystem structure and function
Slope Related to regional or local macro-habitat, influencing freshwater structure
and function
Environmental variables influence freshwater ecosystem

6. 1.4 Freshwater ecosystem: Macroinvertebrate community structure
Individuals Species Dominant species
Individuals, species and dominant species for macroinvertebrate are different
among Taizi river watershed

7. 1.5 Freshwater ecosystem: Fish community structure
Individuals Species
Individuals, species and
dominant species for fishes are
different among Taizi river
watershed
Dominant Species

8. 1.6 Freshwater ecosystem: Alage community structure
Individuals Species
Individuals and species for algae are different among Taizi river watershed

9. 1.7 Results
• Environmental variables changes from the upper Taizi river to
lower Taizi river
• Freshwater community structure changes from the upper Taizi
river to lower Taizi river

10. 2. Why classification
• Spatial heterogeneity of environmental variables
• Spatial heterogeneity of freshwater ecosystem
structure
• Base for river health assessment
• Management demands

11. 3. Method---classification scheme
Data source：DEM，slope，aspect, vegetation type，soil type，annual average
temperature，annual rainfall，annual evaporation；NDVI
aquatic Correlation Analysis between Geostatistic Qualitative
organisms aquatic organisms and analysis of spatial
analysis
survey data environmental variables distribution pattern
cluster
Environmental Indices chosen for the classification
ISODATA
unsupervised classification results
Aquatic
organisms Modify with aquatic Small catchments boundary
cluster map organisms cluster map
Final classification map

12. 4.1 Results
Relationship between freshwater organisms and environmental factors
Environmental variables influences freshwater ecosystem structure, so its
pattern can be used to reflect the freshwater ecosystem pattern in Taizi river
watershed

13. 4.2 Results
Spatial autocorrelation range calculated from geostatistic
NDVI
DEM slope Annual Annual Annual
Evaporation Temperature Precipitation
Range 101.28 KM 84.43 KM 132.1 KM 87.28 KM 100.3 KM 92.37 KM
DEM and precipitation were suitable for the classification
Database
Annual average rainfall
DEM

14. 4.3 Results
ISODATA unsupervised classification results in ERDAS

15. 4.4 Results
Check with freshwater organisms and boundary revision
Freshwater
organisms
Classification by Small watershed
pattern
natural attributes boundary
Ⅲ Plain agriculture region
Ⅰ Mountainous forest region
Ⅱ Hill forest region

16. 4.5 Ⅰ Mountainous forest region
Region Watershed features River feature Freshwater ecosystem
Mountainous Area: 4557KM2， Mean river width 14.79 m (0.5-100m)； Dominant fishes: Leuciscus waleckii、
forest Mean DEM: 511m； Mean substrate index: 3.6 (1-4.8)；Mean Cottus pollux, Odontobutis obscurus;
region Annual average temperature: suspended solid: 33.7mg/L (3.5～ Dominant macroinvertebrate:
2.28-7.75； 347mg/L)；Mean DO: 10.8 mg/L (4.3～ Ecdyonurus viridis, Paraleptophlebia
Annual average precipitation: 15.6 mg/L); Mean conductivity: 183μs/cm japonica；Above ground herbaceous
786-954mm (11.7～826μs/cm) biomass: 1.04kg/m2，belowground:
0.55 kg/m2，Total: 1.68 kg/m2

17. 4.6 Ⅱ Hill forest region
Region Watershed features River features Freshwater ecosystem
Hill Area: 3896KM2; Mean river width: 44.4m (0.3-300m)； Dominant fishes: Ctenogobius brunneus,
forest Mean DEM: 282m； Mean substrate index: 3.4(1-4.4)； Hemicculter Leuciclus,
Mean annual temperature: 6.9℃ Squalidus chankaensis;
region Mean suspended solid: 30.3 mg/L(5.5～
(4.38-9.22℃)； Dominant macroinvertebrate:
81.5 mg/L) ；
Mean annual average precipitation: Cheumatopsyche sp., Antocha sp., and
Mean DO: 9.4mg/L (3.5～14.6 mg/L)；
784mm(717-868mm) Beatis thermicus；
Mean conductivity: 336.8μs/cm (57～
Above ground herbaceous biomass:
566μs/cm)
1.25kg/m2，belowground: 0.72 kg/m2，
Total: 1.97 kg/m2

18. 4.7 Ⅲ Plain agriculture region
Regions Watershed features River features Freshwater ecosystem
Plain Area: 4749KM2; Mean river width: 84m(1-400m); Almost no fish, occasional
agriculture Mean DEM: 65m； Mean substrate index: 2.1(1-4.2); species Ctenogobiusgiurinus；
region Mean annual temperature: Mean suspended solid: 32.3 Above ground herbaceous
8.6℃(4.9-10℃)； mg/L(3.5～109 mg/L); biomass: 1.51kg/m2，
mean annual precipitation: Mean DO: 6.4 mg/L(0.4-13mg/L); belowground: 0.93 kg/m2，
708.8 mm (653.6-775.1mm) Mean conductivity: 515μs/cm(177～ Total: 2.45 kg/m2
1126μs/cm)

19. Thanks for your attention!