Atlas de l'eau du bassin de la Volta = Water atlas of the Volta basin

The water atlas of the Volta Basin presents a set of data collected or developed under a research programme on water use in this cross-border river basin. These date reveal unique basin-scale characteristics that are key to better management of a resource on which inhabitants of the basin and the surrounding areas are dependent for their food supply and welfare. L'atlas de l'eau du bassin de la Volta regroupe un ensemble de donnees collectees ou elaborees lors d'un programme de recherche sur les usages de l'eau dans le bassin transfrontalier de la Volta. Apparaissent ainsi, a l'echelle du bassin, des caracteristiques originales dont la connaissance est precieuse pour mieux gerer une ressource qui conditionne l'alimentation et le bien-etre des habitants du bassin et des regions peripheriques

Human place and response learning: navigation strategy selection, pupil size and gaze behavior.

In this study, we examined the cognitive processes and ocular behavior associated with on-going navigation strategy choice using a route learning paradigm that distinguishes between three different wayfinding strategies: an allocentric place strategy, and the egocentric associative cue and beacon response strategies. Participants approached intersections of a known route from a variety of directions, and were asked to indicate the direction in which the original route continued. Their responses in a subset of these test trials allowed the assessment of strategy choice over the course of six experimental blocks. The behavioral data revealed an initial maladaptive bias for a beacon response strategy, with shifts in favor of the optimal configuration place strategy occurring over the course of the experiment. Response time analysis suggests that the configuration strategy relied on spatial transformations applied to a viewpoint-dependent spatial representation, rather than direct access to an allocentric representation. Furthermore, pupillary measures reflected the employment of place and response strategies throughout the experiment, with increasing use of the more cognitively demanding configuration strategy associated with increases in pupil dilation. During test trials in which known intersections were approached from different directions, visual attention was directed to the landmark encoded during learning as well as the intended movement direction. Interestingly, the encoded landmark did not differ between the three navigation strategies, which is discussed in the context of initial strategy choice and the parallel acquisition of place and response knowledge

Route planning with transportation network maps: an eye-tracking study.

Planning routes using transportation network maps is a common task that has received little attention in the literature. Here, we present a novel eye-tracking paradigm to investigate psychological processes and mechanisms involved in such a route planning. In the experiment, participants were first presented with an origin and destination pair before we presented them with fictitious public transportation maps. Their task was to find the connecting route that required the minimum number of transfers. Based on participants' gaze behaviour, each trial was split into two phases: (1) the search for origin and destination phase, i.e., the initial phase of the trial until participants gazed at both origin and destination at least once and (2) the route planning and selection phase. Comparisons of other eye-tracking measures between these phases and the time to complete them, which depended on the complexity of the planning task, suggest that these two phases are indeed distinct and supported by different cognitive processes. For example, participants spent more time attending the centre of the map during the initial search phase, before directing their attention to connecting stations, where transitions between lines were possible. Our results provide novel insights into the psychological processes involved in route planning from maps. The findings are discussed in relation to the current theories of route planning

Opportunities for harnessing the increased contribution of glacier and snowmelt flows in the Ganges Basin

Keynote speech presented at the International Conference on Cooperation on the Ganges: Barriers, Myths, and Opportunities, Institute of Water Policy, LKY School, National University of Singapore, Singapore, 13-14 November 2010The topography of Ganges basin (GB) is much contrasted with upstream steep mountainous region of the Himalayas and downstream large fertile plains in eastern India and Bangladesh. The Himalays are partly covered by snow and glaciers that seasonally release water to the river network of GB and provide cushion against the annual fluctuations. The contribution from the glaciers to the streamflows is supposed to be significant although spatilly distributed quantification is unavailable. Moreover, there is uncertainity on the impact of climate change on glaciers and the resultant streamflows. We set up an application of the Water Evaluation and Planning (WEAP)model which contained an experimental glaciers module that accounts for snow and glaciers processes in the GB. The model also examined the possible impacts of an increase in temperature of +1, +2 or +3 degree Celsius over 20 years of the simulation period (1982-2002). The average annual stream flows in the GB that comes from melting of snow and ice in glaciated areas is significant (60-75%) in the Upper Ganga and in the Nepalese sub-basins. The share, however, reduces significantly further downstream, falling to about 19% at Farakka as flows from glaciated areas are diluted by streamflows generated by rainfall/ runoff processes. Climate change-induced rise in temperature logically increases the quantity of snow and ice that melts in glaciated areas , causing an augmentation of streamflows. However, this impact decreases from upstream ( +8% to +26% at Tehri Dam in Uttaranchal in India) to downstream (+1% to +4% at Farakka in West Bengal). Such increases in streamflows may create flood events more frequently or of higher magnitude in the Upper Ganga or in the mountainous sub-basins. In terms of water use, most of the extra water from glaciated areas do not flow when water is most required i.e. during the lean flow winter and early summer season. Potential strategy to exploit this additional water may include construction of new dams/ reservoir storages that could be used locally or within the transboundary agreements or to capture this extra water just at the end of the dry season (April-June) when flows from glaciated areas become noticeable. Enhancing the development of groundwater in the basin (from the present low level of ~ 30 per cent) through managed aquifer recharge and other suitable options shall be an equally viable option. The riparian states within India and India-Nepal- Bangladesh may harness this opportunity to alleviate physical water scarcity and transboundary water conflicts

A decision-support tool for water allocation in the Volta Basin

The first version of a decision-support tool (DST) for the management of the transboundary water resource of the Volta Basin is presented in this article. The DST coupled a hydrologic model with the Water Evaluation and Planning (WEAP) water-allocation model. It was calibrated and validated by reproducing observed river flows and water stored in the hydropower reservoirs, respectively. It considered the impact of possible future climate changes (potentially critical) and the development of upstream small reservoirs (leading to upstream-downstream trade-offs) on the Akosombo hydropower scheme. This DST may foster transboundary dialogue for the integrated management of the basin's water resources