17.3 Environmental Flow Assessment and Water Resources…
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in Taizhou). It also supplies water for the irrigation of about 66,667 ha (1 million
mu) of cultivated land. The Niutoushan Reservoir in the city of Linhai was built in
1989 and is mainly used to supply two irrigation districts. About two-thirds of its
302 million m
3 capacity is used to irrigate almost 2,100 ha (about 313,000 mu). The
Lishimen Reservoir is on the upper reaches of Shifeng Creek (which joins Yong’an
Creek). It has a capacity of 199 million m
3 and is used for urban water supply (to
the township of Tiantai), irrigation supply, and hydropower generation. The Xia’an
Reservoir is on the western boundary of Taizhou Prefecture. It has a capacity of
135 million m
3 . There is also a large number of smaller storages throughout the
prefecture, generally maintained by villages.
Groundwater resources are limited, generally very shallow, and over-exploited.
The extent of artesian groundwater development has caused serious land subsidence. Consequently, most artesian boreholes are being closed (with only some to be
retained for contingencies). Areas of restriction or prohibition have been established
in the most overdeveloped sub-artesian groundwater areas. Groundwater resources
are essentially reserved for low impact use such as livestock and domestic uses.
17.3.2 Environmental Flow Definition
17.3.2.1 Reach Definition
The problem of environmental flow assessment and the issue of implementation
of the agreed regime requires simplification of the river system into a manageable
number of reasonably homogeneous reaches. The Jiaojiang River study area was
divided into 6 distinct reaches (Fig. 17.1 and Table 17.1):
Reach 1: Zhuxi (Zhu Creek) between the dam site and the first major downstream
tributary entering Zhuxi.
Reach 2: Zhuxi between the first major tributary below the dam site and the
downstream confluence with Yong’anxi.
Reach 3: Yong’anxi between the Zhuxi confluence and Shifengxi junction, the
approximate upper limit of tidal influence.
Reach 4: The freshwater estuarine section of Lingjiang (downstream of Shifengxi
junction), which is under tidal influence but above the upper limit of saltwater
intrusion from the sea.
Reach 5: The estuarine section of Lingjiang (to the Yogningjiang junction), which
is influenced by both tidal and salinity fluctuations.
Reach 6: The estuarine section of Jiaojiang (downstream of the Yogningjiang
junction to Taizhou Bay), which is influenced by both tidal and salinity fluctuations.
At the same time, the key flow components are identified according to the hydrograph of the Jiaojiang River, which serve important physical and biological functions,
365
in Taizhou). It also supplies water for the irrigation of about 66,667 ha (1 million
mu) of cultivated land. The Niutoushan Reservoir in the city of Linhai was built in
1989 and is mainly used to supply two irrigation districts. About two-thirds of its
302 million m
3 capacity is used to irrigate almost 2,100 ha (about 313,000 mu). The
Lishimen Reservoir is on the upper reaches of Shifeng Creek (which joins Yong’an
Creek). It has a capacity of 199 million m
3 and is used for urban water supply (to
the township of Tiantai), irrigation supply, and hydropower generation. The Xia’an
Reservoir is on the western boundary of Taizhou Prefecture. It has a capacity of
135 million m
3 . There is also a large number of smaller storages throughout the
prefecture, generally maintained by villages.
Groundwater resources are limited, generally very shallow, and over-exploited.
The extent of artesian groundwater development has caused serious land subsidence. Consequently, most artesian boreholes are being closed (with only some to be
retained for contingencies). Areas of restriction or prohibition have been established
in the most overdeveloped sub-artesian groundwater areas. Groundwater resources
are essentially reserved for low impact use such as livestock and domestic uses.
17.3.2 Environmental Flow Definition
17.3.2.1 Reach Definition
The problem of environmental flow assessment and the issue of implementation
of the agreed regime requires simplification of the river system into a manageable
number of reasonably homogeneous reaches. The Jiaojiang River study area was
divided into 6 distinct reaches (Fig. 17.1 and Table 17.1):
Reach 1: Zhuxi (Zhu Creek) between the dam site and the first major downstream
tributary entering Zhuxi.
Reach 2: Zhuxi between the first major tributary below the dam site and the
downstream confluence with Yong’anxi.
Reach 3: Yong’anxi between the Zhuxi confluence and Shifengxi junction, the
approximate upper limit of tidal influence.
Reach 4: The freshwater estuarine section of Lingjiang (downstream of Shifengxi
junction), which is under tidal influence but above the upper limit of saltwater
intrusion from the sea.
Reach 5: The estuarine section of Lingjiang (to the Yogningjiang junction), which
is influenced by both tidal and salinity fluctuations.
Reach 6: The estuarine section of Jiaojiang (downstream of the Yogningjiang
junction to Taizhou Bay), which is influenced by both tidal and salinity fluctuations.
At the same time, the key flow components are identified according to the hydrograph of the Jiaojiang River, which serve important physical and biological functions,