(a) Unconfined water in loose rock pores
The unconfined water in loose rock pores is mainly distributed in the piedmont
alluvial-pluvial fans of the Chaidamu Mountains and recharged through river water
infiltration in the mountainous areas. Groundwater abundance varies in the
alluvial-pluvial fans that are restricted by the water yield property of the basin. For
example, the Reshuigou alluvial-pluvial fan is less abundant in groundwater than
the Baligou pluvial fan. According to the hydrogeological data, in the front edge of
the alluvial-pluvial fan, groundwater bearing capacity is large, with shallow depth
to water table. For example, the quantity reaches 3000–5000 m
3 /d in the modern
riverbeds and ancient rivers channels of the Baligou pluvial fan and 1000–3000 m
3 /
d on both sides of the fan, but it is less than 1000 m
3 /d in other areas. By chemical
analysis, the groundwater is categorized into HCO 3 Á Cl–Na Á Ca type with salinity
less than 1 g/L.
The tectonic analysis reveals that the groundwater of northeastern Dayangtougou
River flows along the ancient river channels into the south of the Dachaidan Town.
The groundwater quantity is less than 1000 m
3 /d, and groundwater is categorized
into HCO 3 Á Cl–Na Á Ca type with salinity less than 1 g/L. It indicates groundwater
replenishment from Datougou to the groundwater discharge zone in the southern
part of the study area. Groundwater in Baligou and Datouyanggou has certain
hydraulic connection in the discharge zone at the front edge of the alluvial-pluvial
fan.
(b) Confined water in loose rock pores
The confined water in loose rock pores is distributed in the Yike Chaidamu Lake
Basin south of the Dachaidan Town. The groundwater mainly exists in the form of
confined water with descending salinity from top to bottom. As exposed in boreholes, 1–6 aquifers were found within the depth of 117 m, and the water head was
3–5 m above the land surface in some areas. The aquifer mainly contains gravel and
gravelly fine sand. The unconfined aquifer on the top is 3–5 m from the water table
and 10–30 m thick, and features Cl–Na type water with salinity of 1–3 g/L. The
single-well water outflow is less than 100 m
3 /d. The confined aquifer of artisan
water at the bottom contains gravel and fine sand, with the upper bed less than 50 m
from water table. The single-well water outflow is 100–1000 m
3 /d, and the salinity
of the HCO 3 Á Cl–Na Á Ca type water is less than 1 g/L.
Carbonate rock fissure-karst water
Carbonate rock fissure-karst water is mainly distributed in the middle and low
mountainous areas south of Qaidam Mountains. The aquifer is composed of the
limestone, dolomite and crystalline of the Upper Carboniferous Zhongwu
Nongshan Group. As weathering fissures and tectonic fissures have been formed,
the groundwater is mainly recharged by precipitation. Due to the deep gully, bare
rock and steep terrain of the carbonate rock distribution area, the groundwater is
rapidly discharged after recharged as runoff replenishment for surface water. Such
160
5 Application Cases
The unconfined water in loose rock pores is mainly distributed in the piedmont
alluvial-pluvial fans of the Chaidamu Mountains and recharged through river water
infiltration in the mountainous areas. Groundwater abundance varies in the
alluvial-pluvial fans that are restricted by the water yield property of the basin. For
example, the Reshuigou alluvial-pluvial fan is less abundant in groundwater than
the Baligou pluvial fan. According to the hydrogeological data, in the front edge of
the alluvial-pluvial fan, groundwater bearing capacity is large, with shallow depth
to water table. For example, the quantity reaches 3000–5000 m
3 /d in the modern
riverbeds and ancient rivers channels of the Baligou pluvial fan and 1000–3000 m
3 /
d on both sides of the fan, but it is less than 1000 m
3 /d in other areas. By chemical
analysis, the groundwater is categorized into HCO 3 Á Cl–Na Á Ca type with salinity
less than 1 g/L.
The tectonic analysis reveals that the groundwater of northeastern Dayangtougou
River flows along the ancient river channels into the south of the Dachaidan Town.
The groundwater quantity is less than 1000 m
3 /d, and groundwater is categorized
into HCO 3 Á Cl–Na Á Ca type with salinity less than 1 g/L. It indicates groundwater
replenishment from Datougou to the groundwater discharge zone in the southern
part of the study area. Groundwater in Baligou and Datouyanggou has certain
hydraulic connection in the discharge zone at the front edge of the alluvial-pluvial
fan.
(b) Confined water in loose rock pores
The confined water in loose rock pores is distributed in the Yike Chaidamu Lake
Basin south of the Dachaidan Town. The groundwater mainly exists in the form of
confined water with descending salinity from top to bottom. As exposed in boreholes, 1–6 aquifers were found within the depth of 117 m, and the water head was
3–5 m above the land surface in some areas. The aquifer mainly contains gravel and
gravelly fine sand. The unconfined aquifer on the top is 3–5 m from the water table
and 10–30 m thick, and features Cl–Na type water with salinity of 1–3 g/L. The
single-well water outflow is less than 100 m
3 /d. The confined aquifer of artisan
water at the bottom contains gravel and fine sand, with the upper bed less than 50 m
from water table. The single-well water outflow is 100–1000 m
3 /d, and the salinity
of the HCO 3 Á Cl–Na Á Ca type water is less than 1 g/L.
Carbonate rock fissure-karst water
Carbonate rock fissure-karst water is mainly distributed in the middle and low
mountainous areas south of Qaidam Mountains. The aquifer is composed of the
limestone, dolomite and crystalline of the Upper Carboniferous Zhongwu
Nongshan Group. As weathering fissures and tectonic fissures have been formed,
the groundwater is mainly recharged by precipitation. Due to the deep gully, bare
rock and steep terrain of the carbonate rock distribution area, the groundwater is
rapidly discharged after recharged as runoff replenishment for surface water. Such
160
5 Application Cases