1. Effects of Lake-Basin Morphological and
Hydrological Characteristics on the
Eutrophication of Shallow Lakes in Eastern China
Presenter ： Jian Huang
Advisor ： Xixi Wang
Date ： 11/14/2014
Jian Huang, Qiujin Xu, Beidou Xi, Xixi Wang, 2014. Effects of lake-basin morphological
and hydrological characteristics on the eutrophication of shallow lakes in east China.
Journal of Great Lakes Research, 40, 666-674.

2. China Eastern China
Lake area > 1 km2
2,300+ 700+
1/3
The Eastern Area

3. Outline
Introduction
Materials and methods
Results
Discussion

4. Shallow lakes are easily shifted to a new trophic state
1) dimictic nature (Havens et al., 2001)
2) high concentration of suspended solids (Vicente et al., 2012)
3) lack of long-term, stable thermal stratification (Verbruggen et al., 2011)
4) nutrients migrating from sediments into the water (Søndergaard et al., 1992;
2013)
The Characteristics of Shallow Lakes
Introduction
Thus, water quality [e.g., total nitrogen (TN) and total
phosphorus (TP)] of shallow lakes is sensitive to human
activity as well as to climatic and hydrological conditions.

5. Introduction
Extensive studies have been conducted to better understand
mechanisms of algal blooms in shallow, eutrophic lakes.
Study design included
 long-term observations of climate
change (Spears et al., 2012)
site-specific experiments (Roessink et
al., 2010)
analysis of nutrient cycling and
trophic dynamics (Kokfelt et al., 2010)
model simulation (Mooij et al., 2010)
These studies have taken into account:
 climate change (Fragoso Jr et al.,
2011)
 external nutrient load (Sas, 1989)
in-lake process (Huang et al., 2009)
For a shallow lake, water quality is susceptible not only to climate
change and human activity but also to the size of the lake basin and
its hydrological characteristics.

6. Lake Tai
HR
MYR
LT
Lake Hongze
Lake Chao
Lake Poyang
Lake Dongting
Hukou
Yichang

7. The objective
The objective of this study was to determine the effects of lake
morphology and hydrology on eutrophication for 90 typical shallow
lakes in eastern China.
We hypothesized that eutrophication of shallow lakes is affected both
by lake-basin morphology and hydrology.
Introduction
• Lake morphological factors: mean and maximum water depth (Zmean
and Zmax ) and surface water area (SA).
• Hydrological factors: hydrologic connectivity and drainage
characteristics

8. Variable Symbol
Sample
Size
Minimum Maximum Mean
Primary Production
Chlorophyll-a (μg/L) Chl-a 68 0.54 43.09 13.38
Physical parameters
pH pH 83 6.81 9.22 7.85
Secchi depth (cm) SD 63 11.2 1652 55.2
Dissolved oxygen (mg/L) DO 84 6.02 17.39 9.27
Electrical conductivity (μs/cm) EC 76 0.26 3795 406
Chemical parameters
Total nitrogen (mg/L) TN 90 0.19 13.54 1.82
Total phosphorus (mg/L) TP 90 0.00 0.65 0.16
Ammonia nitrogen (mg/L) NH4-N 90 0.05 9.9 0.68
Phosphate (mg/L) PO4-P 68 0.00 0.14 0.06
Lake morphology
Typical surface area (km2
) SA 83 1.5 3841 201
Mean depth (m) Zmean 78 0.93 8.4 2.42
Maximum depth (m) Zmax 75 1.31 23.5 4.44
Relative depth Zrel
[1]
76 0.006 0.255 0.066
Hydrology
Drainage area (km2
) DA 28 21 257,000 25,913
Recharge coefficient Rc 28 3.70 197.00 30.77
Typical water level (m) Z 37 1.42 33.00 13.43
Typical volume (108
m3
) V 40 0.10 155.42 11.29
Retention time (d) tr 16 18 458 120

9. Data and preprocessing
Data
Data on Chl-a concentration, physicochemical properties , morphology,
and hydrology for the 90 study lakes were obtained from the Chinese
Research Academy of Environmental Sciences (CRAES) for the period
2008 to 2011.
Lake morphology (SA, Zmean and Zrel) and hydrologic characteristics
were chosen as the independent variables, while Chl-a and nutrient
concentrations (TN and TP) were chosen as dependent variables.

10. Materials and methods -- classified
Mean depth (Zmean): very shallow = Zmean ≤ 2 m, shallow = Zmean > 2 m)
Surface area (SA): small = SA ≤ 25 km2
, large = SA > 25 km2
Relative depth (Zrel)computed as suggested by Köiv et al. (2011),
where Zmax is the maximum water depth.
Morphology
Relative depth

11. Materials and methods -- classified
Lake Tai
HR
MYR
LT
Lake Hongze
Lake Chao
Lake Poyang
Lake Dongting
Hukou
Yichang
Three groups : middle Yangtze River, Lake Tai and Huaihe River
basins. 30 lakes are hydraulically connected to the river and 60 isolated
from the river.
Hydrology

12. • Mean depth Zmean was found to
negatively affect TN (Fig.b) and TP
(Fig.c) concentrations (p-value <
0.03),
• but it had no significant influence
on Chl-a (Fig.a) growth (p-value =
0.44).
Results I - Effects of mean depth (Zmean)
R² = 0.0089
0
5
10
15
20
25
30
35
40
45
50
0 1 2 3 4 5 6 7 8 9
Chl-aConcentration(µgL-1)
Zmean (m)
(a)
R² = 0.1069
0
1
2
3
4
5
6
0 1 2 3 4 5 6 7 8 9
TNConcentration(mgL-1)
Zmean (m)
(b)
R² = 0.1025
-0.1
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0 1 2 3 4 5 6 7 8 9
TPConcentration(mgL-1)
Zmean (m)
(c)

13. Results II- Effects of mean depth (Zmean) and surface area (SA)
Small Large Small Large
0
10
20
30
40
50
DEPTH CLASS
AREA CLASS
shallow
Chl-aConcentration(μgL-1
)
Very shallow
Small Large Small Large
0
1
2
3
4
5
6
DEPTH CLASS
AREA CLASS
shallow
TNConcentration(mgL-1
)
Very shallow
Small Large Small Large
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
DEPTH CLASS
AREA CLASS
shallow
TPConcentration(mgL
-1
)
Very shallow
(a) (b) (c)
Zmean ≤ 2m, very shallow Zmean > 2m, shallow
SA ≤ 25 km2
,
small
SA > 25 km2
,
large
SA ≤ 25 km2
,
small
SA > 25 km2
,
large
Chl-a (ug L-1
) Fig.a 9 10 20 8
TN (mg L-1
) Fig.b 1.2 1.8 0.9 1.1
TP (mg L-1
) Fig.c 0.09 0.15 0.05 0.05

14. • Chl-a (a) tended to increase with increase
of Zrel for the lakes with SA ≤ 25 km2
, while
it tended to decrease with increase of Zrel
for the lakes with SA > 25 km2
.
• Concentrations of both TN (b) and TP (c)
decreased with increase of Zrel regardless of
SA.
Results III- Effects of relative depth Zrel
0.05 0.10 0.15 0.20 0.25
-5
0
5
10
15
20
25
30
35
40
45
Chl-aConcentration(μgL
-1
)
Area = 25km＜ 2 Area 25km＞ 2
0.00 0.02 0.04 0.06 0.08 0.10
-5
0
5
10
15
20
25
30
35
40
45
Zrel
Zrel
0.05 0.10 0.15 0.20 0.25
-1
0
1
2
3
4
5
6
TNConcentration(mgL
-1
)
Area = 25km＜ 2
0.00 0.02 0.04 0.06 0.08 0.10
-1
0
1
2
3
4
5
6
Zrel
Zrel
Area 25km＞ 2
0.05 0.10 0.15 0.20 0.25
-0.1
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
TPConcentration(mgL-1)
Area = 25km＜ 2
0.00 0.02 0.04 0.06 0.08 0.10
-0.1
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
Zrel
Zrel
Area 25km＞
2
(a) (b)
(c)

15. (1) The TN and TP concentrations were lower in the (Middle Yangtze River)
MYR lakes than in the (Lower Yangtze River) LT and (Huaihe River) HR
lakes.
(2) The lakes in the lower Yangtze River basin had the highest Chl-a
concentrations.
(3) The HR lakes had higher TN and TP concentrations, but it had lower Chl-a
concentrations.
Results IV- Effects of lake-river hydraulic connectivity
Lake Tai
HR
MYR
LT
Lake Hongze
Lake Chao
Lake Poyang
Lake Dongting
Hukou
Yichang
Lower TN, TP
Highest Chl-a
Higher TN, TP

16. • As expected, the mean depth, surface area, and electrical
conductivity (EC) in the lakes hydrologically connected with rivers
were higher than in the isolated lakes,
• while the concentrations of TN, TP, and Chl-a in the lakes isolated
from the river were higher than the lakes hydrologically connected
with rivers.
Results V - Effects of lake-river hydrologic connectivity
Connected with
River(s)?
Number
of Lakes
SA
(km2
)
Zmean
(km2
)
EC
(μs/cm)
DO
(mg/L)
TN
(mg/L)
NH4-N
(mg/L)
TP
mg/L
Chl-a
(μg/L)
Connected 30 367 2.56 2778 9.00 1.66 0.49 0.14 12.06
Isolated 60 107 2.33 883 9.41 2.14 0.88 0.18 13.92

17. • TN and TP were found to decrease with increase of Zmean.
Discussion – lake morphology
Such negative relationships between nutrient levels and water depth are consistent with
our common knowledge.
• Chl-a concentration in the lakes with SA >25 km2
and Zmean < 2 m
significantly differed from those in the lakes with SA > 25 km2
and Zmean >
2 m.
Thus, Chl-a increase is affected not only by temperature, nutrient concentrations, and light
intensity, but it also depends on Zmean and SA because these two variables control the extent of
energy needed for vertical mixing and hence the rate of recycling nutrients into the trophogenic
production zone (Kolding and Zwieten, 2006).
• Chl-a concentration increased as Zrel increased in the lakes with SA ≤ 25
km2
but the concentration decreased as Zrel increased in the lakes with SA
> 25 km2
.
Relative depth has widely been used as a surrogate of morphology in assessing
limnological characteristics of lakes.

18. • Both TN and TP were lower in the MYR lakes than in the LT and HR
lakes.
Discussion - Drainage characteristics
• The water quality of the lakes hydraulically connected with rivers was
better than that the isolated lakes.
Since 1949, the middle and lower Yangtze River basins have lost one-third of their
original lake areas to agriculture (Yin and Li, 2001), while many lakes that used to
be naturally connected with rivers have become either isolated or dam-controlled.
Lake
Dongting Lake Poyang Lake Chao Lake Tai
Connected with
River(s)?
Connected Connected Isolated Isolated
Retention time (d) 18 30 210 310
Location Middle Middle Lower Lower

19. • Compared with well-studied shallow lakes in North America (e.g.,
Saginaw Bay of Lake Michigan, Lake Erie, and Lake St. Clair the Lakes in
the US) and in Europe (azLake Balaton in Europe), our Chinese study
lakes have much higher concentrations of TP, TN, and Chl-a.
Discussion - Comparison with other selected shallow lakes
The average TP and TN concentrations in our study lakes are about 3 to 5 times
higher than those in Saginaw Bay (Dolan et al., 1978; Dyle, 2012), Lake Erie
(Herdendorf and Rockwell, 1983; LEW, 2013), Lake St. Clair (MCM, 2013), and
Lake Balaton (EuLakes, 2011; Pintér et al., 2008).
In terms of observed historical trends, from a long-term
perspective, concentrations of TN, TP, and Chl-a all tend
to decrease.

20. Thank you