Watershed classification in Taizi

River

孔维静

Chinese Research Academy of

Environmental Sciences

Outline

• 1. Natural, geographical and freshwater

ecosystem features in Taizi river watershed

• 2. Why classification

• 3. Method

• 4. Results

1.1Overview

40° 29′ -41°40′N

122 ° 25 ′-124 ° 55 ′E

Temperate continental monsoon climate

Area: 12,000KM2

Province: Liaoning

DEM Geomorphology Soil type

Annual average temperature Annual average rainfall Vegetation

1.2 Environment variables for Taizi river watershed

Environment

variables Rationale

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

1.3 Environmental variables and its ecological importance

Environmental variables influence freshwater ecosystem

1.4 Freshwater ecosystem: Macroinvertebrate community structure

Individuals Dominant species Species

Individuals, species and dominant species for macroinvertebrate are different

among Taizi river watershed

1.5 Freshwater ecosystem: Fish community structure

Individuals Species

Dominant Species

Individuals, species and

dominant species for fishes are

different among Taizi river

watershed

1.6 Freshwater ecosystem: Alage community structure

Individuals Species

Individuals and species for algae are different among Taizi river watershed

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

2. Why classification

• Spatial heterogeneity of environmental variables

• Spatial heterogeneity of freshwater ecosystem

structure

• Base for river health assessment

• Management demands

3. Method---classification scheme

Data source：DEM，slope，aspect, vegetation type，soil type，annual average

temperature，annual rainfall，annual evaporation；NDVI

Qualitative

analysis of spatial

distribution pattern

Geostatistic

analysis

Correlation Analysis between

aquatic organisms and

environmental variables

Environmental Indices chosen for the classification

unsupervised classification results

Final classification map

Small catchments boundary Modify with aquatic

organisms cluster map

aquatic

organisms

survey data

Aquatic

organisms

cluster map

cluster

ISODATA

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

4.2 Results

DEM slope Annual

Evaporation

Annual

Temperature

Annual

Precipitation

NDVI

Range 101.28 KM 84.43 KM 132.1 KM 87.28 KM 100.3 KM 92.37 KM

Spatial autocorrelation range calculated from geostatistic

DEM and precipitation were suitable for the classification

DEM Annual average rainfall

Database

4.3 Results

ISODATA unsupervised classification results in ERDAS

4.4 Results

Check with freshwater organisms and boundary revision

Classification by

natural attributes Small watershed

boundary

Ⅰ Mountainous forest region

Ⅱ Hill forest region

Ⅲ Plain agriculture region

Freshwater

organisms

pattern

Region Watershed features River feature Freshwater ecosystem

Mountainous

forest

region

Area: 4557KM2，

Mean DEM: 511m；

Annual average temperature:

2.28-7.75；

Annual average precipitation:

786-954mm

Mean river width 14.79 m (0.5-100m)；

Mean substrate index: 3.6 (1-4.8)；Mean

suspended solid: 33.7mg/L (3.5～

347mg/L)；Mean DO: 10.8 mg/L (4.3～

15.6 mg/L); Mean conductivity: 183μs/cm

(11.7～826μs/cm)

Dominant fishes: Leuciscus waleckii、

Cottus pollux, Odontobutis obscurus;

Dominant macroinvertebrate:

Ecdyonurus viridis, Paraleptophlebia

japonica；Above ground herbaceous

biomass: 1.04kg/m2，belowground:

0.55 kg/m2，Total: 1.68 kg/m2

4.5 Ⅰ Mountainous forest region

Region Watershed features River features Freshwater ecosystem

Hill

forest

region

Area: 3896KM2;

Mean DEM: 282m；

Mean annual temperature: 6.9℃

(4.38-9.22℃)；

Mean annual average precipitation:

784mm(717-868mm)

Mean river width: 44.4m (0.3-300m)；

Mean substrate index: 3.4(1-4.4)；

Mean suspended solid: 30.3 mg/L(5.5～

81.5 mg/L) ；

Mean DO: 9.4mg/L (3.5～14.6 mg/L)；

Mean conductivity: 336.8μs/cm (57～

566μs/cm)

Dominant fishes: Ctenogobius brunneus,

Hemicculter Leuciclus,

Squalidus chankaensis;

Dominant macroinvertebrate:

Cheumatopsyche sp., Antocha sp., and

Beatis thermicus；

Above ground herbaceous biomass:

1.25kg/m2，belowground: 0.72 kg/m2，

Total: 1.97 kg/m2

4.6 Ⅱ Hill forest region

Regions Watershed features River features Freshwater ecosystem

Plain

agriculture

region

Area: 4749KM2;

Mean DEM: 65m；

Mean annual temperature:

8.6℃(4.9-10℃)；

mean annual precipitation:

708.8 mm (653.6-775.1mm)

Mean river width: 84m(1-400m);

Mean substrate index: 2.1(1-4.2);

Mean suspended solid: 32.3

mg/L(3.5～109 mg/L);

Mean DO: 6.4 mg/L(0.4-13mg/L);

Mean conductivity: 515μs/cm(177～

1126μs/cm)

Almost no fish, occasional

species Ctenogobiusgiurinus；

Above ground herbaceous

biomass: 1.51kg/m2，

belowground: 0.93 kg/m2，

Total: 2.45 kg/m2

4.7 Ⅲ Plain agriculture region

Thanks for your attention!