Spoil banks: effects on a coastal marsh water-level regime

Reasons of the extremely high water level in Lake Khanka (it was 0.5 m higher the historical maximum over the past years) have been revealed within the frameworks of the carried out exploration. The lake capacity characteristics alteration due to the natural and anthropogenic factors’ impact has been assessed. We have considered the factors that form the Lake Khanka level regime, i.e. natural: atmosphere circulation, atmospheric perspiration, river inflow to the lake, evaporation from the lake surface, and outflow; anthropogenic: economic activities on the catchment on Russian and Chinese territories (hydro/melioration and the runoff transfer). The passage capacity of the Sungachi River, the only outflow from the lake, has been analyzed in details at different water levels in Lake Khanka. The paper is based on summing up and analysis of information on the lake hydro/meteorological regime and economic activities on its catchment, as well as reference literature. As a result of the study the authors for the first time has identified the main reason of the abnormal rise of the Kanka level. It was found that the significant transformation of the lake level regime occurred due to the Mulinkhe Rivers runoff transfer to Lake Malaya Khanka from the People’s Republic of China. A forecast of the lake level for 2016 taking into consideration different scenarios of the basin moistening has been given. In connection with the forecasted rise of the water level in Lake Khanka in the nearest future we propose a number of measures aimed to minimize inevitable damage to the Russian party.

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Quantitative assessment of water level regime alterations during 1959–2016 caused by Three Gorges Reservoir in the Dongting Lake, China

Water Science & Technology Water Supply ◽

10.2166/ws.2020.369 ◽

2020 ◽

Author(s):

Hongxiang Wang ◽

Yongwei Zhu ◽

Hufei Zha ◽

Wenxian Guo

Keyword(s):

Water Level ◽

Three Gorges Reservoir ◽

Negative Impact ◽

Terrestrial Ecosystems ◽

Dongting Lake ◽

Water Levels ◽

Three Gorges ◽

Hydrologic Alteration ◽

Lake Ecosystems ◽

Level Regime

Abstract Water level is considered as the key factor affecting the structure and function of lake ecosystems. The Mann-Kendall technique and range of variability approach were used to quantitatively evaluate the hydrologic alteration due to Three Gorges Reservoir in Dongting Lake. Results indicate the following: (1) The average annual water levels at Chenglingji station showed increasing trends (p < 0.05), while that at Nanzui station showed a decreasing trend (p < 0.05). The turning year occurred in 2003, which reflects the significant effects of the TGR on the water level regime. (2) The highly altered parameters were 1-, 3-, and 7-day minimum water levels both at Chenglingji and Yangliutan, and October both at Nanzui and Yangliutan, with the degree of hydrologic alteration being larger than 80%. However, 1-, 3-, 7-, and 30-day maximum water levels at three stations were relatively small alteration, with the degree of hydrologic alteration being smaller than 41%. (3) The hydrologic alteration degrees at Chenglingji, Nanzui and Yangliutan station were all moderate, with changes of 50, 46 and 49%, respectively. (4) Water level regimes at Dongting Lake were mainly jointly affected by reservoir operation, land utilization change and river channelization. These changes in water level regimes have a negative impact on aquatic and terrestrial ecosystems. This study provides a scientific reference for the protection of lake ecosystems under hydrologic alteration.

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PROPOSAL OF GROUND WATER LEVEL REGIME USING NUMERICAL MODELLING

17th International Multidisciplinary Scientific GeoConference SGEM2017, Science and Technologies in Geology, Exploration and Mining ◽

10.5593/sgem2017/12/s02.028 ◽

2017 ◽

Author(s):

Dana Barokova

Keyword(s):

Numerical Modelling ◽

Ground Water ◽

Water Level ◽

Ground Water Level ◽

Level Regime

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Groundwater–surface water relations in regulated lowland catchments; hydrological and hydrochemical effects of a major change in surface water level management

10.5194/hess-2017-636 ◽

2018 ◽

Author(s):

Joachim Rozemeijer ◽

Janneke Klein ◽

Dimmie Hendriks ◽

Wiebe Borren ◽

Maarten Ouboter ◽

...

Keyword(s):

Land Use ◽

Surface Water ◽

Water Level ◽

Water Exchange ◽

Overland Flow ◽

Water Levels ◽

Pumping Stations ◽

Level Regime ◽

Solute Fluxes ◽

Water Level Management

Abstract. In lowland deltas with intensive land use such as The Netherlands, surface water levels are tightly controlled by inlet of diverted river water during dry periods and discharge via large-scale pumping stations during wet periods. The conventional water level regime in these polder catchments is either a fixed water level year-round or an unnatural regime with a lower winter level and a higher summer level in order to optimize hydrological conditions for agricultural land use. The objective of this study was to assess the hydrological and hydrochemical effects of changing the water level management from a conventional fixed water level regime to a flexible, more natural regime with low levels in summer and high levels in winter between predefined minimum and maximum levels. Ten study catchments were hydrologically isolated and equipped with controlled inlet and outlet weirs or pumping stations. The water level management was converted into a flexible regime. We used water and solute balance modeling for catchment-scale assessments of changes in water and solute fluxes. Our model results show relevant changes in the water exchange fluxes between the polder catchment and the regional water system and between the groundwater, surface water, and field surface storage domains within the catchment. Compared to the reference water level regime, the flexible water level regime water balance scenario showed increased surface water residence times, reduced inlet and outlet fluxes, reduced groundwater-surface water exchange, and in some catchments increased overland flow. The solute balance results show a general reduction of chloride concentrations and a general increase in N-tot concentrations. The total phosphorus (P-tot) and sulfate (SO4) concentration responses varied and depended on catchment-specific characteristics. For our study catchments, our analyses provided a quantification of the water flux changes after converting towards flexible water level management. Regarding the water quality effects, this study identified the risks of increased overland flow in former agricultural fields with nutrient enriched top soils and of increased seepage of deep groundwater which can deliver extra nutrients to surface water. At a global scale, catchments in low-lying and subsiding deltas are increasingly being managed in a similar way as the Dutch polders. Applying our water and solute balance approach to these areas may prevent unexpected consequences of the implemented water level regimes.

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