Your search found 5 records
1 Eriyagama, Nishadi; Thilakarathne, M.; Tharuka, P.; Munaweera, Tharindu; Muthuwatta, Lal; Smakhtin, V.; Premachandra, Wickrama Waththage; Pindeniya, Dhammi; Wijayarathne, N. S.; Udamulla, L.. 2017. Actual and perceived causes of flood risk: climate versus anthropogenic effects in a wet zone catchment in Sri Lanka. Water International, 42(7):874-892. [doi: https://doi.org/10.1080/02508060.2017.1373321]
Climate change ; Catchment areas ; Flooding ; Anthropogenic factors ; Environmental impact ; Land use ; Urbanization ; Precipitation ; Households ; Satellite imagery ; Paddy fields / Sri Lanka / Kalu Ganga Basin
(Location: IWMI HQ Call no: e-copy only Record No: H048297)
http://www.tandfonline.com/doi/pdf/10.1080/02508060.2017.1373321?needAccess=true
https://vlibrary.iwmi.org/pdf/H048297.pdf
https://vlibrary.iwmi.org/pdf/H048297.pdf
(2.51 MB)
The Kalu Ganga Basin in Sri Lanka is generally flooded once a year. A network of low-lying lands acts as natural retention and storage that captures floodwater, minimizing damage. An increase in the flood frequency has been observed in recent years. It is commonly perceived that this increase is caused by a rise in the frequency and severity of ‘very wet’ precipitation events. We conclude that land-use changes may have played a larger role in generating floods.
2 Eriyagama, Nishadi; Smakhtin, V.; Udamulla, L.. 2018. Centralized versus distributed reservoirs: an investigation of their implications on environmental flows and sustainable water resources management. Proceedings of the International Association of Hydrological Sciences, 378:43-47. [doi: https://doi.org/10.5194/piahs-379-43-2018]
Reservoir operation ; Environmental flows ; Environmental sustainability ; Water resources ; Water management ; Water storage ; Water supply ; Surface water ; Rain ; Ecosystem services ; Stream flow ; River basins / Sri Lanka / Malwatu Oya Basin
(Location: IWMI HQ Call no: e-copy only Record No: H048844)
https://www.proc-iahs.net/379/43/2018/piahs-379-43-2018.pdf
https://vlibrary.iwmi.org/pdf/H048844.pdf
https://vlibrary.iwmi.org/pdf/H048844.pdf
(2.07 MB)
Storage of surface water is widely regarded as a form of insurance against rainfall variability. However, creation of surface storage often endanger the functions of natural ecosystems, and, in turn, ecosystem services that bene t humans. The issues of optimal size, placement and the number of reservoirs in a river basin – which maximizes sustainable bene ts from storage – remain subjects for debate. This study examines the above issues through the analysis of a range of reservoir con gurations in the Malwatu Oya river basin in the dry zone of Sri Lanka. The study produced multiple surface storage development pathways for the basin under different scenarios of environmental ow (EF) releases and reservoir network con gurations. The EF scenarios ranged from “zero” to “very healthy” releases. It is shown that if the “middle ground” between the two extreme EF scenarios is considered, the theoretical maximum “safe” yield from surface storage is about 65–70% of the mean annual runoff (MAR) of the basin. It is also identi ed that although distribution of reservoirs in the river network reduces the cumulative yield from the basin, this cumulative yield is maximized if the ratio among the storage capacities placed in each sub drainage basin is equivalent to the ratio among their MAR. The study suggests a framework to identify drainage regions having higher surface storage potential, to plan for the right distribution of storage capacity within a river basin, as well as to plan for EF allocations.
3 Eriyagama, Nishadi; Smakhtin, V.; Udamulla, L.. 2020. How much artificial surface storage is acceptable in a river basin and where should it be located: a review. Earth-Science Reviews, 208:103294. [doi: https://doi.org/10.1016/j.earscirev.2020.103294]
Surface water ; Water storage ; River basins ; Sustainable development ; Water resources ; Reservoirs ; Dams ; Infrastructure ; Water supply ; Ecological factors ; Ecosystem services ; Hydropower ; Environmental flows ; Flooding ; Sediment ; Social aspects ; Economic aspects ; Indicators
(Location: IWMI HQ Call no: e-copy only Record No: H049809)
https://www.sciencedirect.com/science/article/pii/S0012825220303408/pdfft?md5=ca17ecde7fb5bb659c645ff6c7dc1ce4&pid=1-s2.0-S0012825220303408-main.pdf
https://vlibrary.iwmi.org/pdf/H049809.pdf
https://vlibrary.iwmi.org/pdf/H049809.pdf
(2.30 MB) (2.30 MB)
A key question in sustainable development is how much alteration in natural systems, such as river basins, is acceptable? One of the ways by which humans alter a river basin is by building water storage infrastructure. While storage reservoirs deliver numerous benefits, they can also induce social and environmental costs by displacing people, fragmenting river networks and altering downstream flow regimes. In such a context, merely capping total water withdrawal from rivers for human consumption is not sufficient. River basin plans should also identify optimal (acceptable) limits to surface storage capacities, and optimal numbers, degrees of distribution and locations of storage infrastructure. It remains largely unclear, however, whether it is possible to define a hydrologically, ecologically and socially justified ‘surface water storage boundary’ for a river basin. An associated question is what would be the ‘best’ arrangement of this bounding storage capacity in the basins river network (in terms of numbers, sizes and locations of reservoirs) to maximize water storage benefits and minimize environmental and social costs. The main objective of this review is to examine contemporary knowledge on surface water storage development with a focus on tools and approaches that may help to answer the above questions of a ‘surface water storage boundary’ and its ‘optimum arrangement’ for a river basin. In order to achieve this objective, our review introduces two novel concepts: the ‘storage scale’ and the ‘sustainable storage development framework.’ The ‘storage scale’ has four elements – capacity, number, distribution and location – individual scales that help visualize a ‘surface water storage boundary’ and its ‘optimum arrangement’ for a typical river basin. The ‘sustainable storage development framework’ consists of three dimensions – economic benefits, ecosystems and society- and a set of indicators quantifying each dimension. This review shows that optimal levels of the elements of the ‘storage scale’ may be identified using the ‘sustainable storage development framework’.
4 Eriyagama, Nishadi; Smakhtin, V.; Udamulla, L.. 2021. Sustainable surface water storage development pathways and acceptable limits for river basins. Water, 13(5):645. [doi: https://doi.org/10.3390/w13050645]
Surface water ; Water storage ; Water supply ; Water yield ; River basin management ; Reservoirs ; Planning ; Sustainability ; Strategies ; Environmental flows ; Water extraction ; Runoff ; Dams ; Precipitation ; Case studies ; Models / Sri Lanka / Malwatu Oya Basin / Kalu Ganga Basin
(Location: IWMI HQ Call no: e-copy only Record No: H050319)
(5.81 MB) (5.81 MB)
This paper addresses the questions of acceptable upper limits for storage development and how best to deploy storage capacity in the long-term planning of built surface water storage in river basins. Storage-yield curves are used to establish sustainable storage development pathways and limits for a basin under a range of environmental flow release scenarios. Optimal storage distribution at a sub-basin level, which complies with an identified storage development pathway, can also be estimated. Two new indices are introduced—Water Supply Sustainability and Environmental Flow Sustainability—to help decide which pathways and management strategies are the most appropriate for a basin. Average pathways and conservative and maximum storage limits are illustrated for two example basins. Conservative and maximum withdrawal limits from storage are in the range of 45–50% and 60–65% of the mean annual runoff. The approach can compare the current level of basin storage with an identified pathway and indicate which parts of a basin are over- or under-exploited. A global storage–yield–reliability relationship may also be developed using statistics of annual basin precipitation to facilitate water resource planning in ungauged basins.
5 Eriyagama, Nishadi; Smakhtin, V.; Udamulla, L.. 2022. Sustainable surface water storage development: measuring economic benefits and ecological and social impacts of reservoir system configurations. Water, 14(3):307. (Special issue: Relationship of Energy and Water Resource Availability) [doi: https://doi.org/10.3390/w14030307]
Surface water ; Water storage ; Economic benefits ; Ecological factors ; Social impact ; Water reservoirs ; River basins ; Sustainability ; Equity / Sri Lanka / Malwatu Oya Basin / Kalu Ganga Basin
(Location: IWMI HQ Call no: e-copy only Record No: H050900)
(5.43 MB) (5.43 MB)
This paper illustrates an approach to measuring economic benefits and ecological and social impacts of various configurations of reservoir systems for basin-wide planning. It suggests indicators and examines their behavior under several reservoir arrangement scenarios using two river basins in Sri Lanka as examples. A river regulation index is modified to take into account the volume of flow captured by reservoirs and their placement and type. Indices of connectivity illustrate that the lowest river connectivity in a basin results from a single new reservoir placed on the main stem of a previously unregulated river between the two locations that command 50% and 75% of the basin area. The ratio of the total affected population to the total number of beneficiaries is shown to increase as the cumulative reservoir capacity in a river basin increases. An integrated index comparing the performance of different reservoir system configurations shows that while results differ from basin to basin, the cumulative effects of a large number of small reservoirs may be comparable to those with a few large reservoirs, especially at higher storage capacities.
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