khone phapheng aesthetics: evaluating and ameliorating the ... · season pathway, the engineered...
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Khone Phapheng aesthetics: evaluating and ameliorating the hydraulic and visual impacts of the Don Sahong Hydroelectric Project (Lao PDR)The Don Sahong hydropower scheme, now under construction in the Siphandone (“four thousand islands”) region of Khong District (of Champassak Province) in far southern Laos has been extremely controversial since the Memorandum of Understanding (MoU) was first agreed between the Lao PDR government and MegaFirst Berhad: a Malaysian company with great experience in engineering and land development, but which had never previously built any hydroelectric projects. The initial dust-up was over the Lao PDR’s argument that since the full Mekong mainstem would not be blocked by the proposed design, thus only the lesser tributaries/distributaries submission-and-review criteria under the Mekong Compact needapply to their formal obligations toward the Mekong River Commission (MRC).
The next flap was over the widely-believed —and possibly largely correct— assertion that the Hou Sahong channel, which would in fact be completely blocked by the Project, was the single most critical migratory pathway for migratory fishes moving upstream during the dry season. And would result in “immeasurable damage to nutrition and livelihoods throughout the Lower Mekong Basin”: especially so to Cambodia, with which the Lao PDR border was only 2km below the prospective Don Sahong dam.
The third line of attack by the Project’s critics was that the piscivorous Irriwaddy dolphin (Orcaella brevirostris), IUCN red-listed as “critically endangered” —of which the open water embayment directly at the Lao-Cambodian border was permanent habitat of perhaps ten in-dividuals isolated from the rest of the slender O. brevirostris population— would be severely impacted both by the project’s presumed long-term reduction of fish prey; and by the worri-some physiological effects of construction blasting on a marine mammal with hypersensitive echolocation auditory mechanisms.
(In practice, the emplacement of three temporary cofferdams —one upstream at the entrance to the Hou Sahong channel, and two downstream, above and below the actual damsite— has effected all construction blasting completely in the dry.)
We’ll momentarily put aside these latter two arguments (the first having been rendered moot), in favor of a Project impact that wasn’t even in the critical discourse until mid-2016, when it appeared that the waterfalls aesthetics issue was potentially significant, following the stated concerns of the Lao PDR Ministry of Tourism that the beauty of the Khone Phapeng site —the eastern-most, and by far most easily accessible, of the several cataracts ranged along the 5 km-wide fall line— across the Siphandone island assemblage, was being put as risk.
The relevant hydraulics criteria, here highly simplified, were essentially as follows: during the dry season when overall discharge is lowest, the multiple channels traversing Siphandone are relatively discrete and semi-isolated. This is in marked contrast to monsoonal high-flow con-ditions, when many/most of the interspersing islands (and indeed, the falls escarpments) are effectively submerged and waters from the western channels will freely self-divert throughout the entire channel system: should any of them be blocked by engineering works.
Under the project concept, the pre-project Don Sahong channel —which, being relatively shallow, of high roughness, and containing several internal islands of it own, is not especially hydraulically efficient— would be, and already has been, extensively deepened and partly straightened: in part as the primary source of crushed and trap rock for eventually constructing the main dam itself (and meanwhile used for the three temporary cofferdams already in place).
Compounding the likely significant Q (i.e., discharge) reduction through the Phapeng Channel above and over the falls resulting from the operations of the Don Sahong dam (the turbinated releases from which flow back into Hou Sahong below the Khone Phapheng waterfalls), to mitigate migratory fish losses due to the Project’s closure of the foremost dry season pathway, the engineered enlargements now underway of several other east side chan-nels, notably Hou Saddam and Hou Xang Pheuak, to figure much larger than in the past as alternate dry season fish migratory pathways.
The problem is that the falls at Siphandone are most impressive —displaying spectacular dis-charge, persistent spray clouds, and sheer roar— at the height of the monsoonal rains, which is exactly when the fewest tourists are there; and the obverse case (which is when there’s also the minimal sediment load and the clearest, bluest water, so there’s that) but the “awe-someness factor” is then comparatively modest: yet that’s high season for tourism and what discharge there is through the Phapheng channel would be most impacted,
Don Sahong details
Don Sahong details
homepage Pak Mun museum
Siphandone flythrough
artist's rendering Don Sahong dam
Appearance of western Khone falls (Lee-Pee Somphamit complex)4 March 2014: Q Pakse = 3,845 cumecs
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Ho Chi Minh
Mandalay
Hai Phong
Hue
Lhasa
Qamdo
Pursat 1 Pursat 2
Battambang 1
Battambang 2
Lower Sesan 2
Lower Sesan 3
Lower Sre Pok 3
Lower Sre Pok 4
Prek Liang 1
Sambor
Stung Sen
Stung TrengO Chum 2
Guonian
Mengsong
Dachaoshan
Gongguoqiao
Jinghong
Jinhe
Longqingxia
Manwan
Nuozhadu
Xiaowan
Gushui
Huangdeng
Kagong
Lidi
Miaowei
Wunonglong
Banda
Cege
Dahuaqiao
Ganlanba
Guxue
Rumei
Tuoba
Yuelong
Nam Ko
Nam Lik 2
Nam Mang 3
Nam Ngay
Nam Ngum 1
Nam Theun 2
Theun Hinboun ExpansionTheun-Hinboun
Xeset 2
Nam Khan 2Nam Khan 3
Nam Kong 2
Nam Lik 1
Nam Ou 5Nam Ou 6
Xayaburi
Xe Kaman 3
Xe Xou
Xeset 1Ban KumDak E Mule
Don Sahong
LuangprabangNam Beng
Nam Feuang 2 Nam Feuang 3
Nam Hinboun 1 Nam Hinboun 2
Nam Kong 1
Nam Mang 1
Nam Mouan
Nam NgaNam Ngao
Nam Ngieu
Nam Ngum 4ANam Ngum 4B
Nam Ngum Dam (lower)
Nam Ou 3
Nam Ou 4
Nam Ou 7
Nam Pay
Nam PhaNam Phak (Nam Ou)
Nam Poun
Nam PouyNam San 2
Nam San 3
Nam Suang 1Nam Suang 2
Nam Tha 1
Nam Theun 1
Nam Theun 4
Pak Beng
Pak Lay (Option 1) Pak Lay (Option 2)
Sanakham
Santhing-Pakchom
Thakho
Xe Bang Fai
Xe Bang Hieng 2
Xe Bang Nouan
Xe Kaman 4AXe Kaman 4B
Xe Lanong 1
Xe Lanong 2
Xe Nam Noy 5
Xe Neua
Xe Pon 3
Xedon 2
Xekaman-Sanxay
Xekong 4
Xekong 5
Chulabhorn
Hua Na
Huai Kum
Lam Ta Khong P.S.
Nam Pung
Pak MunRasi Salai
Siridhorn
Ubol Ratana
Lam Takong Dam
Rasi Salai Dam
Nam Un
Buon Kop
Buon Tua Srah
Plei KrongSesan 3
Sesan 4Sesan 4A
Upper Kontum
Yali
Duc Xuyen
Lam Pao
Nong Han
Nam Ang - Tabeng
Nam Phouan
Dak Pla
Lower Sesan 5/1
Sre pok 4A
Lower Ya Soup
Upper Ya Soup
Nam
Ou
Nam
Tha
Sen
Riv
er
Pursa
t River
Nam Sen
g
Nam Beng
Nam M
ae Kok
(Mek
ong)
Nam M
ae In
g
Nam Khan
Sangk
er
R iver
Na
m Ngum
Mekong River
Nam
Ou
Lanc
ang
Jian
g
Na
m
N gum
Tonle Sap (river)
Ch i River
Mun River
Xe Bang Fai
Xe Bang Hieng
S treng River
Mek
ong
Rive
r
Xe K
ong
Sre Pok
Zi Qu
Se San
Mekong River
Za Qu
Tonle Sap (lake)
Mekong
Rive r
Mekong River
L an cang Jiang
(Me
kong)
Dams in the Mekong Basin
C H I N AC H I N A
V I E T N A MV I E T N A MB U R M AB U R M A
T H A I L A N DT H A I L A N D
C A M B O D I AC A M B O D I A
L A O SL A O S
0 100 200 300 400 50050
Kilometers
¹I N D I AI N D I A
G u l f o fT h a i l a n d
S o u t hC h i n a
S e a
G u l f o fT o n k i n
1:7,000,000
Datum : World Geodetic System 1984Coordinate System : Universal Tranverse Mercator Zone 48 North
HA NOI
NAY PYI TAW(NAYPYIDAW)
VIANG CHAN(VIENTIANE)
KRUNG THEP(BANGKOK)
PHNUM PENH(PHNOM PENH)
Yangon(Rangoon)
LegendDams
Status! Planned
! Under construction
! Commissioned
! Cancelled
! Unknown (or irrigation)
Mekong River System
Hierarchy
Mainstream
Tributaries
Lakes & reservoirs
Mekong River basin boundary
Cites
P National capital
R Major city
National boundary
CartographicDesign by :
www.geo-sys.net
Commissioned, Under Construction and Planned Damsin May 2013
Map Description:The map shows every known commissioned, under construction, and planneddam in the basin. ‘Unknown’ dams are mainly dams and reservoirs constructed for use in irrigationand/or water supply, the names of which are currently unknown.
Data Sources :Citations for the data sources contributing to the location of the dams in this map may be foundat our website - http://mekong.waterandfood.org/archives/2648Background relief data is courtesy of Natural Earth and SRTM data from the JPL of NASARiver basin boundary and river vector data is courtesy of the IWMIAll other administrative and physiographic data courtesy of NOAA's National Geophysical DataCenter's Global Self-consistent, Hierarchical, High-resolution Geography Database
Acknowledgements:CPWF-Mekong gratefully acknowledges the financial support of AusAID in the production of this map.This map has been rendered by GeoSys (Lao) Co., Ltd,Hom 7, 136/09, Ban Sokpaluang, Sisattanak District, Vientiane Capital, Lao PDR.
Disclaimer:While every effort has been made to ensure and confirm the accuracy of these data, CPWF-Mekong,AusAID or any partner associated with the CPWF-Mekong program cannot be held responsible forany inaccuracies or omissions in this map. Observations and comments may be sent [email protected]. The designation and names of geographical entities on this map do notimply the expression of any opinion whatsoever on the part of AusAID, CPWF-Mekong or anyassociated partners concerning the legal status of any country, territory, or area, or of its authorities,or concerning the delimitation of its frontiers or boundaries or of the nomenclature deployed inits identification.
Correct Citation:CGIAR Challenge Program on Water and Food. 2013. Dams in the Mekong Basin - Commissioned,Under Construction and Planned Dams in May 2013. Vientiane, Lao PDR: CGIAR Challenge Program onWater and Food.
Creative Commons LicenseThis publication is licensed under a Creative Commons AttributionNonCommercial–NoDerivs 3.0 Unported License.This publication may be freely quoted and reproduced providedthe source is acknowledged. This publication may not be used inwhole or in part for resale or other commercial purposes.
N.B. Not all dam project nameshave been added to the mapdue to space limitations
Lower Siphandone satellite view, showing “fall line”” escarpments and rapids, c. 5km widefrom Lee Pee (left) to Phapheng (right)
“Khone Falls: the Niagara of Southeast Asia” (and if not, why not; even if they both are Class 10, the highest?)
Khone Falls: The Niagara of Southeast Asia?
A common cliché regarding Khone Falls on the Mekong —of which Khone
Phapheng near the left bank, and Lee Phi near the right bank are the two dominant components— is that it’s “the Niagara of Southeast Asia”. No it isn’t:
Niagara Falls, including both the American and the Canadian sections, is about 850m altogether in breadth, and its drop consists largely of a single vertical escarpment of c. 52m in height. The average over-falls discharge at Niagara is c. 2,700 cumecs (i.e., cubic meters per second) which doesn’t change radically with the seasons: varying only c. 20% between annual minimum and maximum. The entire Niagara Falls assemblage can be readily viewed from many vantage points along both banks.
Khone Falls, which lies entirely with the Lao PDR, actually describes a series of individual channels interspersed by rocky and forested islets and islands —the larger amongst them permanently inhabited and under agricul-ture— along the fall line or tectonic fault line in Siphandone (literally “four thousand islands” in Lao), which extends almost 9km from the eastern- most channel bank to the westernmost. Rather than a single escarpment, the aggregate Khone drop of c. 21m, is comprised of a cascade of relatively oblique rapids —as opposed to abrupt vertical escarpments— passing through the fault zone, sometimes occupying a longitudinal gradient of as much as 500m.
The tropical monsoonal hydrological regime of the Mekong Basin result in a typical annual flow variation exceeding a full order of magnitude; i.e., displaying an average dry season discharge at the Pakse gaging station of c. 3,000 cumecs (with a measured minimum of half that figure), and the peak measured rainy season flows there exceeding 40,000 cumecs. Numerous smaller tributaries debouch into those reaches of the Mekong below Pakse and above Khone.
As many of the islands transected by the fall line become partly or com-pletely submerged during the monsoon, the bank-to-bank span actually then under water can be double or even triple of the dry season aggregate channel width. There is no vantage point anywhere —at any time of the year— where the complete Khone Falls assemblage is visible: other than from an aircraft or satellite. What Khone and Niagara do have in common is that of the many thousands of major waterfalls on the planet, only a relative handful are ascribed to Category/Class 10: the most spectacular, as based on a logarithmic relationship between their height and their mean discharge. Also, at least until the Don Sahong project was undertaken, Khone —unlike Niagara— had never been industrialized.
Two grand-scale paintings entitled “Falls of Niagara”, by Frederick E. Church: the horseshoe falls only from the Canadian side (1857, Corcoran Gallery, Washington, DC), and both cataracts from the American side (1867, National Gallery, Edinburgh).
Manually stitched-up panorama from Niagara Falls, Ontario( in non-interactive PDF)
drone video clips of Niagara Falls (left) and Khone Phapeng (right)