Spatial and Temporal Dynamics of Water Hyacinth and Its Linkage with Lake-Level Fluctuation: Lake Tana, a Sub-Humid Region of the Ethiopian Highlands

Water hyacinth originated from the Amazon Basin and has expanded to other parts of the world since the 1800s. In Ethiopia, the weed is affecting the socio-economic activities of the people whose livelihood is directly or indirectly dependent on Lake Tana. Still, the area covered by water hyacinth and the impact of water level fluctuation on the expansion of water hyacinth has not been known clearly. Therefore, the main objective of this study was to determine the spatiotemporal distribution of water hyacinth and relation with lake-level fluctuation. The area covered by water hyacinth was determined using monthly Sentinel-2 images, which were collected from November 2015 to December 2019. The impact of water level fluctuation on the expansion of water hyacinth was evaluated using hourly water level data converted to a monthly average to correlate with the area covered by the water hyacinth. In addition, MOD13Q1.006 data was used to evaluate the trend of the Normalized Difference Vegetation Index (NDVI) and its linkage with the weed. The maximum areas covered by water hyacinth were 278.3, 613.6, 1108.7, 2036.5, and 2504.5 ha in Feb 2015, October 2016, September 2017, December 2018, and in December 2019, respectively. Its areal coverage was declining from the northern corridors and increasing in eastern shores of the lake. The lake-level fluctuation was observed in the range of 1.5 to 3.98 m in this study. The annual mean maximum spatial values of the NDVI were in the range of 0.27 and 0.47. The area covered by water hyacinth was increasing significantly (P < 0.05) and positively correlated with the seasonal lake-level fluctuation. High water level enabled the expansion of the weed by extending its suitable habitat of shallow water to the flood plain. Based on the results of this study, lake-level fluctuations can have an adverse impact on the expansion of the weed.

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Lake level and trophic state variables among a population of shallow Florida lakes and within individual lakes

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f05-177 ◽

2005 ◽

Vol 62 (12) ◽

pp. 2760-2769 ◽

Cited By ~ 14

Author(s):

Mark V Hoyer ◽

Christine A Horsburgh ◽

Daniel E Canfield, Jr. ◽

Roger W Bachmann

Keyword(s):

Water Level ◽

Lake Level ◽

Trophic State ◽

Secchi Depth ◽

Water Level Fluctuation ◽

Water Level Fluctuations ◽

Level Fluctuation ◽

State Variables ◽

Florida Lakes ◽

Lake Level Fluctuation

Monthly total phosphorus, total nitrogen, and chlorophyll concentrations, Secchi depth, and lake water level data for 84 Florida lakes were used to examine relations between trophic state variables and water level fluctuation. Lake size averaged 566 ha (range 4.0 to 5609 ha), with the period of record for individual lakes averaging 57 months (range 7 to 175 months). Lake level fluctuation for individual lakes averaged 1.3 m (range 0.1 to 3.5 m). The lakes also ranged from oligotrophic to hypereutrophic, with average chlorophyll values for individual lakes ranging from 1 to 97 µg·L1. No overall relation between trophic state variables and lake level fluctuation could be found among the population of lakes. However, individual lakes showed direct, inverse, or no significant relations between lake trophic state variables and water level fluctuation, regardless of the magnitude of water level fluctuation. These data suggest that predicting how water level fluctuations will impact trophic state variables among a population of lakes will be difficult, if not impossible, and that any accurate predictions will have to be made after first examining several mechanisms within individual lake systems.

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Spatiotemporal Dynamics and Environmental Controlling Factors of the Lake Tana Water Hyacinth in Ethiopia

Remote Sensing ◽

10.3390/rs12172706 ◽

2020 ◽

Vol 12 (17) ◽

pp. 2706

Author(s):

Abeyou W. Worqlul ◽

Essayas K. Ayana ◽

Yihun T. Dile ◽

Mamaru A. Moges ◽

Minychl G. Dersseh ◽

...

Keyword(s):

Water Level ◽

Air Temperature ◽

Best Management Practices ◽

Water Hyacinth ◽

Lake Level ◽

Management Practices ◽

Satellite Image ◽

Spatiotemporal Dynamics ◽

Lake Tana ◽

Spatial Coverage

The largest freshwater lake in Ethiopia, Lake Tana, has faced ecological disaster due to water hyacinth (Eichhornia crassipes) infestation. The water hyacinth is a threat not only to the ecology but also to the socioeconomic development of the region and cultural value of the lake, which is registered as a UNESCO reserve. This study aims to map the spatiotemporal dynamics of the water hyacinth using high-resolution PlanetScope satellite images and assesses the major environmental variables that relate to the weed spatial coverage dynamics for the period August 2017 to July 2018. The plausible environmental factors studied affecting the weed dynamics include lake level, water and air temperature, and turbidity. Water temperature and turbidity were estimated from the moderate resolution imaging spectroradiometer (MODIS) satellite image and the water level was estimated using Jason-1 altimetry data while the air temperature was obtained from the nearby meteorological station at Bahir Dar station. The results indicated that water hyacinth coverage was increasing at a rate of 14 ha/day from August to November of 2017. On the other hand, the coverage reduced at a rate of 6 ha/day from December 2017 to June 2018. However, the length of shoreline infestation increased significantly from 4.3 km in August 2017 to 23.4 km in April 2018. Lake level and night-time water temperatures were strongly correlated with water hyacinth spatial coverage (p < 0.05). A drop in the lake water level resulted in a considerable reduction of the infested area, which is also related to decreasing nutrient levels in the water. The water hyacinth expansion dynamics could be altered by treating the nutrient-rich runoff with best management practices along the wetland and in the lake watershed landscape.

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Hydrological regime of Adygine lake, Tien Shan, Kyrgyzstan

Geografie ◽

10.37040/geografie2014119040320 ◽

2014 ◽

Vol 119 (4) ◽

pp. 320-341 ◽

Cited By ~ 3

Author(s):

Kristýna Falátková ◽

Miroslav Šobr ◽

Jan Kocum ◽

Bohumír Janský

Keyword(s):

Water Level ◽

Lake Level ◽

Hydrological Regime ◽

Climatic Conditions ◽

Tien Shan ◽

Diurnal Fluctuation ◽

Substantial Part ◽

Level Fluctuation ◽

Lake Level Fluctuation ◽

Specific Factors

This article provides a detailed analysis of the hydrological regime of the Adygine glacial lake in Tien Shan, Kyrgyzstan, and of the specific factors which affect it. Glaciers of central Tien Shan are considered to be very sensitive indicators of climate change. The studied lake belongs to a system of relatively recently formed lakes situated near the front of the retreating glacier and is numbered amongst the potentially dangerous. The lake’s water level and its dependence on the development of climatic conditions in the area were monitored in detail in 2007–2012. A substantial part of this paper is the evaluation of the inflow and outflow balance of the lake’s basin. The results confirmed that the hydrological regime is glacial and exhibits its typical characteristics, such as a seasonal evolution of runoff delay or significant diurnal fluctuation of the lake’s water level. During the monitored period, no major changes in annual lake level fluctuation were recorded.

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Water Level Fluctuation under the Impact of Lake Regulation and Ecological Implication in Huayang Lakes, China

Water ◽

10.3390/w12030702 ◽

2020 ◽

Vol 12 (3) ◽

pp. 702

Author(s):

Zhongya Fan ◽

Zhong Wang ◽

Yiping Li ◽

Wencai Wang ◽

Chunyan Tang ◽

...

Keyword(s):

Climate Change ◽

Water Level ◽

Early Spring ◽

Water Level Fluctuation ◽

Dominant Factor ◽

Ecological Implication ◽

Level Fluctuation ◽

The Past ◽

Lake Volume ◽

The Impact

Water level fluctuation (WLF) in shallow lakes in the middle and lower reaches of the Yangtze River has been a concern of many researchers. This work aims to investigate the effects of climate change and regulation of floodgates and the Three Gorges Dam (TGD) on WLF and lake volume in Huayang Lakes during the past 52 years. The results revealed that precipitation is the dominant factor that leads to seasonal variation of lake levels, whereas regulation of floodgates and TGD are the key drivers of hydrology regime change in the past 20 years. Natural lake regime has higher water level when there is more precipitation and less lake volume. Floodgates and TGD regulations have changed this pattern since 2003, causing less difference in water level in spite of more precipitation and lake recession. Under the combined impacts of floodgates and TGD regulations, Huayang Lakes have experienced a prolonged outflow time since 2003 and the contribution rate caused by the floodgates and TGD regulations has increased by 19.90%. Additionally, the water level of Huayang Lakes decreased by approximately 0.3~0.5 m from September to November, but it showed no alteration from January to March in the past two decades. This indicated that floodgate regulations used for agricultural irrigation and fishery culture dominate the hydrology regime in winter and early spring. This study is beneficial for aquatic ecosystem protection in floodgate-controlled lakes under the circumstance of climate change and vigorous anthropology activities.

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