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Water quality problems

According to the Chinese Surface Water Quality Standard (GB 3838-2002), water quality is broken into five categories that can be described as ‘‘good’’ (Grades I, II, and III) or ‘‘poor’’ (Grades IV and V) or >V, which cannot support drinking and swimming.

There is a spatial difference in water quality trend across the Haihe  river basins in the year 2008. The middle branches of the Yang He and the Sanggan He as part of the Yongding river basin (YRB)  have poor water quality (classes IV and V). Only in the head water regions classes I, II or III can be found. Some stretches of the Sanggan River are even worse than class V, representing ammonium-nitrogen und total phosphorus concentrations higher than 2.0 mg/l. respectively 0,4 mg/l (GB 3838-2002). Summing up the surface water quality is currently poor in more than 30 % of the monitored water sections within the Yongding river basin (YRB) upstream of the Guanting reservoir. The ecological stress posed to the river’s bios like fish, macrozoobenthos, phytobenthos, macrophytes is so severe that besides a few very resistant and modest species no further aquatic live can be often found. By extensive water abstraction mainly for irrigation  and retention of water by large numbers of reservoirs the Yongding river has changed its character from a perennial to an anthropogenic seasonal river (ASR) with up to 300 no-flow days in some years (XU 2004: 18)

The water quality problems, concerning high nutrient inputs, are caused by human impacts such as fertilizer input on agricultural land and waste water which enter the streams directly or indirectly via groundwater passages. 

According to the UMD MODIS landuse map 21 % of the Guanting catchment is covered by agricultural land. In some counties the percentage might even be higher. Thus, due to high fertilizer inputs, excess of nutrients such as nitrogen is washed out from the fields into groundwater entering surface waters. In 2003 hot spots of nitrogen surpluses (60-110 kg/ha·year)  are located in the middle reaches of the Yang and Sanggan river. It can be concluded, that in these areas the nutrient input into surface waters is high, although some nitrogen might be lost due to denitrification processes.

Every year in the upstream areas approximately 100 million m³ of untreated or inadequately treated waste water are discharged into the rivers, amounting to almost one third of the Guanting reservoir’s average annual inflow (DU 2004).

In recent years the trend of degrading water quality has experienced some deceleration and in some parts even improvements by a multiple set of measures.  This combating strategy is pushed forward by the 11th five years (2006 to 2010) since environmental concerns are increasingly incorporated into planning processes both at the national and provincial level. The implementation of this strategy focused mainly on the improvement of waste water treatment.

According to a preliminary environmental investigation of the reservoir in 2003, there were more than 300 industrial and mining enterprises, producing about 7844.76 X 104 t of waste water per year. Most of this waste water was directly discharged into the reservoir without any treatment (Du et al., 2004).

Until the end of the last millenium, even in the larger urban areas such as Zhangjiakou, Xuanhua and Huailai urban waste was discharged without any treatment. Since 2005 several waste water treatment plants (WWTP) have been established of which 10 are known to be situated in the Yongding river basin. Table 1 presents the WWTP which could be detected by using Google Earth in the YRB. While the WWTP’s in Zhangjiakou and two of the six in Datong can manage a waste water amount of 100.000 m³ the other WWTP’s have capacities lower than 70.000 m3/day. Based on these informations one can estimate an equivalent of about 800.000 connected inhabitants – not considering waste water from business and industries. For comparison: in the YRB the population amounts to approximately 8.000.000 in the year 2008 (CIESIN 2005, modified).

Data of the WWTP in Zhangjiakou reveals, that state of the art waste water treatment technologies, such as A/A/O (anaerobic-anoxic-aerobic activated sludge process) are applied. Primary and secondary treatment is common; additional phosphate elimination leads to a phosphate removal of up to 85%, which can be calculated from the given data. Thus these new waste water treatment plants do already improve the nutrient levels

in surface waters, but still the over all waste water treatment rate in the Guanting basin is low, and in rural areas no WWTP exist at all. Thus a higher waste water treatment rate will still improve surface water quality immensely.

Since 1997 the Guanting reservoir could not be used as a source for drinking water of Beijing (WEI et al. 2007: 568). In recent years the Beijing Municipal Water Conservancy Bureau has initiated projects (e.g. prereservoir to improve the water quality of the polluted Guanting reservoir) and attempted to reintegrate the Guanting reservoir into Beijing’s water supply cycle. Since 2008 the GT reservoir can be used again for urban water supply of Beijing.

 

(source: Wechsung, project proposal, revised by IGB Sep 2010)

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