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1 Hecht, J.; McCartney, Matthew; Lacombe, Guillaume; Vogel, R.. 2013. Flow alterations caused by hydropower projects in two Mekong tributary basins: the livelihood implications. [Abstract only]. In German Aerospace Center (DLR); Germany. Federal Ministry of Education and Research (BMBF). Mekong Environmental Symposium, Ho Chi Minh City, Vietnam, 5-7 March 2013. Abstract volume, Topic 01 - Hydropower development and impacts on river ecology. Wessling, Germany: German Aerospace Center (DLR); Bonn, Germany: Federal Ministry of Education and Research (BMBF). pp.17.

Water power ; Energy generation ; Dams ; River basins ; Flow discharge ; Case studies ; Living standards / South East Asia / Laos / Nam Ngum Dam / Theun Hinboun Project / Mekong River Basin

(Location: IWMI HQ Call no: e-copy only Record No: H045746)

http://www.mekong-environmental-symposium-2013.org/frontend/file.php?id=3020&dl=1
https://vlibrary.iwmi.org/pdf/H045746.pdf

(0.08 MB) (2.09MB)

There is increasing concern over projected changes in the magnitude and timing of streamflow due to the construction of hydropower dams in the Mekong basin and elsewhere. We compare a suite of indicators for their ability to reflect changes from pre-dam flow regimes. Using two case studies, we illustrate the differences in hydrologic alteration that take place downstream of dams that are used for (i) in-stream power production (Nam Ngum 1 Dam) and (ii) diverting water to off-stream production sites (Nam Theun-Hinboun Project). We show that dams for in-stream power production reduce wet season flows, increase dry season flows and attenuate both high- and low-flow extremes. In contrast, dams constructed for off-stream power production mildly reduce flood peaks when diversions are possible during extreme high flow conditions while dry season streamflow declines sharply due to the priority placed on hydropower production. Our analysis summarizes the effects of dams on the frequency, duration, timing and rates of change of discharge at sites downstream of dams. We then review the relevance of metrics of hydrologic alteration for assessing impacts of hydropower dams on livelihoods dependent upon the natural variability of the flow regime in monsoonal climate zones.

2 Read, L.; Vogel, R.; Lacombe, Guillaume. 2014. Design metrics for extreme events in a non-stationary world. [Abstract oly] Paper presented at the World Environmental and Water Resources Congress, Portland, Oregon, USA, 1-5 June 2014. 1p.

Statistical methods ; Design ; Water resources ; Planning

(Location: IWMI HQ Call no: e-copy only Record No: H046735)

https://vlibrary.iwmi.org/pdf/H046735.pdf

(0.03 MB)

Society is increasingly concerned with how climate, land use and other anthropogenic influences are impacting their watersheds. Traditional probabilistic approaches for defining risk, reliability and return periods under stationary hydrologic conditions assume that extreme events are serially independent with a probability distribution whose moments and associated parameters are fixed. However, when non-stationary conditions lead to trends in the moments and parameters of extreme value processes, new methods for understanding the impacts of such changes on traditional design metrics are needed to insure sensible planning and design efforts. We document the general behavior of various metrics of return period, risk, and reliability assuming extreme events follow a nonstationary lognormal distribution. Our results provide guidance on the value, application and caveats associated with such metrics for water resources planning in a nonstationary world.

3 Lacombe, Guillaume; Douangsavanh, Somphasith; Vogel, R.; McCartney, Matthew; Chemin, Yann; Rebelo, Lisa-Maria; Sotoukee, Touleelor. 2014. Simple power-law models to predict flow metrics for water resource and risk management along the Mekong tributaries. [Abstract only] Paper presented at the International Conference on Sustainability in the Water-Energy-Food Nexus, Bonn, Germany, 19-20 May 2014. pp.59.

Water resources ; Risk management ; Statistical methods ; Models ; River basins ; Catchment areas / South East Asia / Mekong Basin

(Location: IWMI HQ Call no: e-copy only Record No: H046736)

https://publications.iwmi.org/pdf/H046736.pdf
http://wef-conference.gwsp.org/fileadmin/WEF_Conference/Conference_Programme_Sustainability_in_the_W-E-F_Nexus_web_version.pdf

(0.18 MB)

Increasing demographic pressure, economic development and resettlement policies in the Lower Mekong Basin induce greater population dependency on river flow to satisfy growing domestic and agricultural water demands. This dependency is particularly tight in upland areas where alternative water resources (groundwater) are scarce. As a result, communities tend to live closer to rivers, and so are more vulnerable to floods. This situation requires improved knowledge of flow variability for better management of water resources and risks. Unfortunately, stream flow measurements are scarce, especially in remote areas inhabited by the poorest and most vulnerable populations. Several water resource models have been developed to simulate and predict flows in the Lower Mekong Basin. However, most of these models have been designed to predict flow along the Mekong mainstream, precluding accurate assessments in headwater catchments. In most cases, their complexity and lack of transparency restricts potential users to modelling experts, and largely excludes those practitioners working closely with affected populations. The most integrated and informative way to characterize flow, at a specific location on a river, is to compute a flow duration curve which provides the percentage of time (duration) any particular flow is exceeded over a historical period. Using hydro-meteorological records from more than 60 gauged catchments in the Lower Mekong Basin, and a 90-meter digital elevation model, we used multiple linear regressions to develop power-law models predicting flow duration curves. These simple equations allow assessment of low, medium and high flow metrics, at any point on rivers in the Lower Mekong Basin, using easily determined geomorphological and climate characteristics. We believe that this parsimonious, transparent and highly predictive tool (89% <R2< 95%) can be used by a wide range of practitioners working in the fields of livelihood, water infrastructure engineering and agriculture.