I
(6/1~9/10)
(110)
1 2
6/1~9/10 1
3 17.9
59 1
(9/10 )
TWVD2001
0.413m =TWVD2001
-0.413m
6/1~9/10 ( 5 9 10 )
II
40 1/2,000
365 37m
1 110 4 1,527.279 296.263
15.68 37 309.799
16.86% 19.762 /
2 110 9 1,527.596 296.095
16.10 37 309.482
16.85% 19.227 /
3 110 4 110 9 1,527.279
1,527.596 0.317
0.01%
4 109 9 110 9 1,525.893
1,527.596 1.703
0.09%
1 109 3 109 9
0.1m
2 109 9 110 4
0.1m
3 110 4 110 9
0.1m
4 EL30~31m
(EL28~29m)
III
1 S14-1( 1K+500m)
S14-1 94
94 EL.27.0m 104 EL.28.3m 104 110
EL.28.3m EL.29.0m S14-1
94 104 104 110
2 S02( 1K+900m)
S02 94
S08-1 94 EL.26.4m 104
EL.28.8m 104 110 EL.27.9m
;
1 109 (
)
-0.16~+0.11m
-0.13~+0.10m -0.07~+0.19m -0.11~-0.01m
-0.88~+0.01m 37~42
(-0.88~-0.49m) -34,543m3
-56,352m3 61.3%
2 109 (
) -0.070m +0.003m
+0.028m -0.050m
-0.369m +0.055m -0.040m
IV
Abstract
This program contains varies data collected from Agongdian Reservoir and Agongdian Rivers which include: basic information, land survey investigation, setting of concrete survey marker, and the altitude and horizontal measurements of control point and survey marker. Topographic surveys of the reservoir were carried out before and after the Empty Storage Operation for Sediment Prevention Program (ESOSPP) (June 1 to September 10).
A river cross-section profile survey was carried out after the ESOSPP to establish the data for Pre-post Emptying Storage Sediment Prevention Topography report and the downstream river cross-section of 2021. All the data allow a better understanding of the current water storage capacity and topographical changes circumstances. The related data can also be used as a reference for future ESOSPP.
I. Scope of Work and Content
This program includes:
1. Coordinate and elevation measurements of the new concrete survey markers located around the Agongdian Reservoir area and the upstream river section.
2. Topographic survey and river cross-section profile survey of the Agongdian Reservoir area and the upstream river channel, respectively before and after the ESOSPP (June 1 to September 10).
3. Cross-section profile survey of the reservoir water outlet and estuary (17.9km distance in total and 59 river cross-section surveys). This survey was executed after the ESOSPP (September 10).
Since this survey includes the Agongdian Reservoir and the Agongdian River, both adopt different elevation systems. The relationship between two systems are therefore explained as below:
The Agongdian River survey uses the Ministry of Interior TWVD2001 level elevation system. On the other hand, the Agongdian Reservoir survey uses its own elevation system so called The Agongdian Reservoir Elevation System. Thus, the altitude differences
V
between both systems has been determined to 0.413m. It converts into the following formula: Agongdian Reservoir Elevation System = TWVD2001 Elevation System 0.413m
II. Agongdian Reservoir Topographic Survey Results
Since the Agongdian Reservoir Improvement Project was completed, the ESOSPP has been carried out during the flooding period. In order to understand the effectiveness of the ESOSPP, a topographic survey of the reservoir must be achieved to evaluate the existing volume, the erosion and the deposit variation. Thus, the topographic survey was achieved respectively before and after the ESOSPP (one was before the end of May and the other one was after September 10th).
The Agongdian survey ranges from the bottom of the reservoir to the 40m height marker (highest flood level) at a 1/2000 survey mapping scale for a total area of 365 hectares. The comparison between before and after the ESOSPP with maximum water storage height at the 37m marker are as follows:
1. 2021 April survey result:
Water storage capacity = 1,527.279 Water storage area = 296.263
After a period of more than 15 years (from 2005 August to 2021 April), the accumulated sediment volume of the reservoir at 37m marker water level was 309.799 . Deposit rate at 16.86% and the annual average sedimentation is
19.762 /year.
2. 2021 September survey result:
Water storage capacity = 1,527.596 Water storage area = 296.095
After a period of 16 years (from 2005 August to 2021 September), the accumulated sediment volume of the reservoir at 37m marker water level was 309.482 .
VI
Deposit rate at 16.85% and the annual average sedimentation is 19.227 /year.
3. 2021 April and 2021 September surveys comparison:
The water storage volume has increased by 0.317 , which represents a 0.01% increment ratio.
4. 2020 September to 2021 September surveys comparison:
The water storage volume has increased by 1.703 , which represents a 0.09% increment ratio.
III. Landform Changes in Solar Panels Area
From 2020 March to 2020 September, the terrain elevation showed a situation of mutual increase and decrease, and the magnitude was about ± 0.1m.
From 2020 September to 2021 April, the terrain elevation showed a situation of mutual increase and decrease, and the magnitude was about ± 0.1m.
From 2021 April to 2021 September, the terrain elevation showed a situation of mutual increase and decrease, and the magnitude was about ± 0.1m.
The landform changes of the solar panel area is consistent with the trend of the surrounding area.
The elevation of the solar panel area is about EL. 30m to EL. 31m. When the ESOSPP performed, the hydraulic sand discharge from the deep trench to the overflow pipe is located at EL. 28m to EL. 29m. The water storage height of the reservoir does not reach the height of the solar panel area. Therefore, no sand falling and silting in this area and no distinct changes in invasion and silting.
IV. Changes in the Cross-Section of the Reservoir
The changes in the Wanglai River profile over the years has a clear distinction at cross-section S14-1 (mileage at about 1K + 500m). From the cross-section S14-1 to
VII
the overflow pipe opening, the reservoir bottom bed has been increasing since 2005 to 2015. The elevation of the bottom of the reservoir has increased form EL. 27m to EL. 28.3m. From 2015 to 2021, the elevation of the bottom of the reservoir has increased form EL. 28.3m to EL. 29m. On the upstream of the cross-section S14-1, there was a decreasing trend from 1994 to 2015. The decreasing trend gradually reduced between 2015 and 2021. The data shows both increase and decrease in elevation of mutual perception.
The changes in the Zhuoshui River profile section over the years can be
distinguished at the entry point of the cross-section S02 (mileage approximately at 1K + 900m). From the cross-section S02 to the overflow nozzle, the elevation of the reservoir bottom bed has been increased since 2005. As a reference, the elevation from the cross section S08-1 is located at the bottom of the reservoir.
From 2005 to 2015, the elevation increases from EL. 26.4m to EL. 28.8m. From 2015 to 2021, the elevation decreases from EL. 28.8m to EL. 27.9m. Therefore, the upper reach of the river has both increase and decrease in elevation, which has a more various development.
V. Agongdian River Cross-Section Survey Result
1. Comprising between this year and last year riverbed elevation changes (Positive means siltation, negative means erosion) base on the cross-section and is as follow:
Agondian river estuary - Weiren Bridge: Mainly has erosion. Flushing elevation at about -0.16m to +0.11m.
Weiren Bridge - Tuku drainage: equally siltation and erosion. Flushing elevation at about -0.13m to +0.10m.
Tuku drainage - train railway bridge: mainly siltation. Flushing elevation at about -0.07m to +0.19m.
Train railway bridge - Guoxi Bridge: mainly erosion. Flushing elevation at about
VIII
-0.11m to -0.01m.
Guoxi Bridge - high-speed railway Bridge: mainly erosion. Flushing elevation at about -0.88m to +0.01m. Moreover, Cross-section 37 to Cross-section 42 have the biggest flushing in this profile survey (from -0.88m to -0.49m). The flushing volume is about -33,543 , which represents 61.3% of the whole river flushing volume, -56,352 .
2. Comprising between this year and last year deposit result, the average deposit height variation (Positive means siltation, negative means erosion) has been determined by the cross-section and is as follow :
Agondian river estuary - Weiren Bridge: -0.070m Weiren Bridge - Tuku drainage: +0.003m
Tuku drainage - train railway bridge: +0.028m Train railway bridge - Guoxi Bridge: -0.050m Guoxi Bridge - high-speed railway bridge: -0.369m
High-speed railway bridge - reservoir water outlet: +0.055m The whole river section variation: -0.040m
IX
1. 110 9 109 9
37m 1,527.596
1,525.893 1.703
0.09%
2. 110 9 110 4
37m 1,527.596
1,527.279 0.317 0.01%
3. 94 8 110 9
37m 1,837.078
1,527.596 16.10 37
309.482 16.85% 19.227
/
4. S14-1( 1K+500m)
S14-1 94
94 EL.27.0m 104 EL.28.3m 104 110
EL.28.3m EL.29.0m S14-1 94 104
104 110
5. S02( 1K+900m)
S02 94
S08-1 94 EL.26.4m 104 EL.28.8m
104 110 EL.27.9m ;
6. 109
X
-0.070m +0.003m +0.028m
-0.050m -0.369m
+0.055m -0.040m
1. 40 2
2. 10 0.5
( 109 5 )
3.
4. (EL.29m)
5. 43.12
6.06 10.7
1.70
6.
