Elsevier

Advances in Water Resources

Volume 94, August 2016, Pages 185-199
Advances in Water Resources

Is China's fifth-largest inland lake to dry-up? Incorporated hydrological and satellite-based methods for forecasting Hulun lake water levels

https://doi.org/10.1016/j.advwatres.2016.05.010Get rights and content

Highlights

  • Severe reduction of river discharge is the key factor behind the lake water decline.

  • Water diversion project prevented a further water lever decline of > 0.5 m by 2012.

  • The water balance model can provide a useful tool to manage lake water resources.

Abstract

Hulun Lake, China's fifth-largest inland lake, experienced severe declines in water level in the period of 2000-2010. This has prompted concerns whether the lake is drying up gradually. A multi-million US dollar engineering project to construct a water channel to transfer part of the river flow from a nearby river to maintain the water level was completed in August 2010. This study aimed to advance the understanding of the key processes controlling the lake water level variation over the last five decades, as well as investigate the impact of the river transfer engineering project on the water level. A water balance model was developed to investigate the lake water level variations over the last five decades, using hydrological and climatic data as well as satellite-based measurements and results from land surface modelling. The investigation reveals that the severe reduction of river discharge (-364 ± 64 mm/yr, ∼70% of the five-decade average) into the lake was the key factor behind the decline of the lake water level between 2000 and 2010. The decline of river discharge was due to the reduction of total runoff from the lake watershed. This was a result of the reduction of soil moisture due to the decrease of precipitation (-49 ± 45 mm/yr) over this period. The water budget calculation suggests that the groundwater component from the surrounding lake area as well as surface run off from the un-gauged area surrounding the lake contributed ∼ net 210 Mm3/yr (equivalent to ∼ 100 mm/yr) water inflows into the lake. The results also show that the water diversion project did prevent a further water level decline of over 0.5 m by the end of 2012. Overall, the monthly water balance model gave an excellent prediction of the lake water level fluctuation over the last five decades and can be a useful tool to manage lake water resources in the future.

Introduction

Hulun Lake is the fifth-largest inland lake in China, which is located in northeast China close to the borders of China, Russia and Mongolia (Fig. 1). For many decades, the freshwater from the lake has sustained vast areas of wetlands which provide habitats for a variety of wildlife, including many species of fish and endangered migratory birds (e.g., Red-crowned Crane). The importance of Hulun Lake wetlands for the ecosystem has been recognised by international communities. In 2002, it was declared a Ramsar Wetlands of International Importance and chosen by UNSECO as a site for the World Network of Biosphere Reserves. However, the lake water level has been reported to have declined by approximately 4 metres over the last decade. The amount of river inflow into the lake has been reduced to approximately 40% of the five-decade average. This has resulted in the reduction of the total lake surface area by > 25% and total water volume by > 60% (Wang, 2012). The rapid decline of the lake water level has prompted concerns over whether the lake is disappearing gradually (Liu et al., 2013, Tao et al., 2015). The local government has recently spent several million US dollars on an engineering project to divert a river's flow into the lake, by constructing a canal linking a nearby river to the lake.

Fluctuations of the lake water level during the 20th century as well as its impact on the lake ecosystem and the surrounding mining industries have attracted more attention from the academic community and local and regional water resource authorities for several decades. The historical and instrumental records show that during the last century the lake has experienced three wet (1900-1926, 1952-1964 and 1984-1999) and two dry (1927-1951 and 1965-1981) periods. The first and second wet periods brought the lake water level up from 537 m above sea level (asl) (less than 1 m in depth) in 1900 to a record level of 545.3 m asl in 1964 (Qin and Wang, 1993, Qin and Wang, 1994). The rise of the water level during the second wet period increased the lake water discharge into the Dalaneluoumu River (Fig. 1) which endangered the mining industries alongside the river due to flooding. Thus, a number of dams were constructed by the local authorities to block the lake water discharge into the Dalaneluomu River in 1958 and as a consequence, the lake became a closed lake. As the lake water level continually rose and reached the record level of 545.3 m asl in 1964, concerns were raised about the potential flooding of nearby regions. A man-made water canal (Xinkai River, Fig. 1) was then constructed in 1971 as a new outflow channel for the lake water discharge with a designed rate of 40.7 m3/s when the water level exceeds 544.8 m asl (Xu et al., 1989).

The second dry period of the lake in the last century, similar to the first one, caused a water level decline of approximately 3 m which began to attract scientific attention. Studies to investigate the link between climate change and the lake water level variation were conducted in the early 1990s. The reduction of river water discharge into the lake was identified as the key factor behind the observed water level decline (Qin and Wang, 1993, Qin and Wang, 1994). Sediment core investigations conducted in order to construct the paleoclimate of the lake region suggested that the lake has experienced severe water level fluctuations since the late Glacial period (Xue et al., 2003). In addition, studies of the lake water quality also raised concerns with regard to the eutrophication of the lake's water (Han and Yang, 2002, Yan et al., 2001). The recent dry period which started in 1999 as well as the elevation of the mean temperature during the last two decades in the lake region has attracted more attention than previous dry periods. Further studies of the lake sediment cores have also been conducted to investigate the paleoclimate of the lake region to improve the understanding of recent climatic variations. The paleoclimate reconstruction suggested that in the recent 500 years the lake has expanded and the water salinity has decreased due to the warmer and wetter weather conditions (Xiao et al., 2009, Zhai et al., 2011). With the reduction of the river discharge into the lake, eutrophication became a major issue threatening the lake's ecosystem (Chen et al., 2012, Chuai et al., 2012) together with increased salinity (Li et al., 2006a). Remote sensing data also revealed that the decline in water level increased the grassland degradation around the lake area during this period (Wang et al., 2012).

Despite the report of the severe decline of the lake water level over the last decade, research into the underlying processes has faced tremendous challenges due to the lack of in-situ lake water level measurements. This is because the hydrological station at Dalai (Fig. 1) which has provided daily water level measurements via an in-situ staff gauge since 1960 was discontinued from the early 1980s. There are some annual lake water level measurements from 1981 onwards which can be obtained from the local authorities, but the source of the data is unclear. Several studies have attempted to reconstruct the water level from the 1980s to early 2000s using a water balance model approach (e.g., Li et al., 2006a, Li et al., 2006b), but the accuracy of the model prediction is difficult to assess without reliable water level measurements. However, studies over the last decade show that satellite radar altimetry can estimate water level time series with reasonable accuracy, which can provide an alternative to permanent gauging stations (Alsdorf et al., 2000, Coe and Birkett, 2004, Frappart et al., 2006, Zhang et al., 2006, Awange et al., 2013). TOPEX/Poseidon (T/P) altimetry measurements have been reported to investigate six lake level variations including Hulun Lake during the period between 1993 and 2001 (Hwang et al., 2005).

The objective of this study was to advance the understanding of key processes controlling the lake water level variations over the last 50 years, and develop a quantitative tool to predict the lake water sources as well as assess the impact of the water diversion engineering project. This study conducted a comprehensive analysis of over 50 years of climatic and hydrological data obtained from the ground-based monitoring stations in the lake region. In addition to the ground-based data, satellite data as well as results from the Global Land Data Assimilation System (GLDAS) (Rodell et al., 2004) were used to assess the changes of hydrological conditions within the ∼150,000 km2 lake watershed over the last two decades. These ground- and satellite-based observations, as well as the results from regional and continental modelling from a GLDAS land surface model, enabled us to conduct joint data analyses across both the lake regional and watershed scales. These combined data analyses helped to understand the impacts of climate change on the lake water level fluctuations as well as the hydrologic cycle across both scales. The conceptual understanding of the hydrological processes of the lake and its watershed support the development of a quantitative tool to model the lake water level variations over the past 50 years. The validated model was then used to assess the impact of the water transfer engineering project, since its construction, on the lake water level.

Section snippets

Hulun lake and its hydrological system

Hulun lake (48o30’ - 49o20’ N, 117o00’ – 117o41’ E) is China's fifth-largest inland lake in surface area, which is located in the sparsely populated Hulun Buir Steppe of northeast China close to the borders of China, Russia and Mongolia (Fig. 1). The lake has an area of 2000 km2 with an average water depth of 5-6 m and a maximum depth of approximately 8 m. There are no settlements around the lake. The north-western side of the lake is surrounded by low mountains and hills of Mesozoic volcanic

Meteorological and hydrological stations

Data from four meteorological and hydrological stations each in the lake region were used in this study (Fig. 1). Meteorological data include daily precipitation, mean temperature, wind speed, relative humidity and sunshine duration from 1960 to 2014. Meteorological stations B & C also include daily pan evaporation measurements over the period of 1960-2013, except some data are missing for the period between 1965 and 1974. Most of the evaporation measurements were carried out by the ϕ20 cm pan

Lake water level fluctuations

Fig. 3 shows the hydrological data of Hulun Lake over the last five decades, including the lake water level (above sea level), precipitation, pan-evaporation and river influx rate. The annual water levels from 1960 to 1980 presented in Fig. 3a are the averages of daily measurements from an in-situ gauging station at hydrological station E. There are two data sources for the lake water level after the discontinuation of hydrological station E in the early 1980s: 1) Reported annual level from a

Conclusions

The analyses of hydrological and climatic data in the Hulun Lake region showed that over the last five decades the lake has experienced one wet (1981-1998) and two dry (1964-1980, 1999-2012) periods. The two dry periods resulted in the decline of the lake water level by 3 and 4 m, respectively. The wet period brought the water level up to the recent highest level and increased the lake surface water outflow. The combined analysis of precipitation and river discharge for these three periods

Acknowledgement

This research is indirectly supported by a research grant aided by the Irish Department of Communications, Energy and Natural Resources under the National Geoscience Programme 2007–2013, and partly supported by the National key Basic Research Program of China (2013CB733302) and the Major International (Regional) Joint Research Program of NSFC (41210006). The views expressed in this paper are the authors’ own and do not necessarily reflect the views and opinions of the Minister of

References (45)

  • ChuaiX et al.

    Effects of climatic changes and anthropogenic activities on lake eutrophication in different ecoregions

    Int. J. Environ. Sci. Technol.

    (2012)
  • MT Coe et al.

    Calculation of river discharge and prediction of lake height from satellite radar altimetry: example for the lake chad basin

    Water Resour. Res.

    (2004)
  • NK Davi et al.

    Is eastern Mongolia drying? A long-term perspective of a multidecadal trend

    Water Resour. Res.

    (2013)
  • MB Ek et al.

    Implementation of noah land surface model advances in the national centers for environmental prediction operational mesoscale eta model

    J. Geophys. Res

    (2003)
  • F Frappart et al.

    Water volume change in the lower Mekong from satellite altimetry and imagery data

    Geophys. J. Int.

    (2006)
  • GB Fu et al.

    Investigating the conversion coefficients for free water surface evaporation of different evaporation pans

    Hydrol. Process.

    (2004)
  • FR Hampel et al.

    Robust Statistics - The Approach Based on Influence Functions

    (1986)
  • HanX et al.

    An analysis of the self-purification function of hulun lake and its effect on regional environmental conservation

    J. Nat. Resour.

    (2002)
  • HuoW.

    China's great dispearing lake

    (2011)
  • HwangCW et al.

    Lake level variations in China from TOPEX/Poseidon altimetry: data quality assessment and links to precipitation and ENSO

    Geophys. J. Int.

    (2005)
  • M Joana Fernandes et al.

    Atmospheric corrections for altimetry studies over inland water

    Remote Sens.

    (2014)
  • LiC et al.

    Reconstruction of the hydrology series and simulation of salinity in ungauged Lake Hulun

    J. Lake Sci.

    (2006)
  • Cited by (45)

    View all citing articles on Scopus
    View full text