Ten fundamental questions for water resources development in the Ganges: myths and realities

Abstract

This paper summarizes the results of the Ganges Strategic Basin Assessment (SBA), a 3-year, multi-disciplinary effort undertaken by a World Bank team in cooperation with several leading regional research institutions in South Asia. It begins to fill a crucial knowledge gap, providing an initial integrated systems perspective on the major water resources planning issues facing the Ganges basin today, including some of the most important infrastructure options that have been proposed for future development. The SBA developed a set of hydrological and economic models for the Ganges system, using modern data sources and modelling techniques to assess the impact of existing and potential new hydraulic structures on flooding, hydropower, low flows, water quality and irrigation supplies at the basin scale. It also involved repeated exchanges with policy makers and opinion makers in the basin, during which perceptions of the basin could be discussed and examined. The study's findings highlight the scale and complexity of the Ganges basin. In particular, they refute the broadly held view that upstream water storage, such as reservoirs in Nepal, can fully control basin-wide flooding. In addition, the findings suggest that such dams could potentially double low flows in the dry months. The value of doing so, however, is surprisingly unclear and similar storage volumes could likely be attained through better groundwater management. Hydropower development and trade are confirmed to hold real promise (subject to rigorous project level assessment with particular attention to sediment and seismic risks) and, in the near to medium term, create few significant tradeoffs among competing water uses. Significant uncertainties – including climate change – persist, and better data would allow the models and their results to be further refined.

Biophysical Modelling of the Ganges, Brahmaputra, and Meghna Catchment

“…Flow, sediment, and nutrient fluxes can provide critical information that can assist the Indian and Bangladesh governments to mitigate future impacts. There are several existing modelling studies on the Ganges river, most of which were funded by either government departments or international organisations, such as the World Bank (Sadoff et al 2013). In order to undertake an assessment of the hydrology and nutrient dynamics in the GBM rivers, the semi-distributed, process-based INCA model (INtegrated Catchment model) for nitrates (N) and phosphates (P) is applied to the whole of the GBM river systems (Whitehead et al 2015a, b).…”

Transboundary water interaction III: contest and compliance

“…In recent years, World Bank-funded activities under South Asian Water Initiative attempt to develop knowledge as well as networks between countries and stakeholders in multiple basins of the South Asian region (see, e.g. Sadoff et al 2013)(World Bank 2014). An underlying challenge for sustainability is that both Nepali and Indian hydrocracies subscribe to the view of utilising the river to maximise its economic benefits (Mirumachi 2015: 71-73).…”

Reviving the “Ganges Water Machine”: where and how much?

“…Popular belief is that having large dams is the only option to meet the basin's water storage needs (Onta, 2001). However, contrary to that, the Ganges strategic basin assessment conducted by the World Bank (2012) found that the sustainable use of the basin's vast groundwater aquifers can store far greater volumes of water compared to the potential of man-made storage in the basin, which is about 130-145 billion m 3 (Sadoff et al, 2013). For instance, the mean annual replenishable groundwater in the Ganges basin is about 202.5 billion m 3 (Ministry of water resources, 2014).…”

“…The major causes of floods in the downstream areas are the shallow groundwater table and high monsoonal rainfall in these areas, and the large runoff generated in the upstream sub-basins. Previous studies (Revelle and Lakshminarayana, 1975;Sadoff et al, 2013) indicated that, due to the limitation of the construction of large surface reservoirs, recharging groundwater beyond the natural level is the best way to control floods downstream. Subsurface storage (SSS) also allows one to meet water requirements during the dry months.…”

“…However, the excess pumping of water from the aquifer can affect the dry season flows. Sadoff et al (2013) mentioned that using aquifers to store excess water is a national-level alternative for upstream water storage and has the potential to argument dry season flows (although it requires other factors such as appropriate energy pricing and policy environment in conjunction with a wellmanaged surface water system). Khan et al (2014) suggest that not withdrawing water from the river during the dry season (which makes up to 50 % of the 28 billion m 3 of the annual water withdrawal) in the state of Uttar Pradesh (UP) will increase flow by 25 % in the Ganges at the UP-Bihar boundary.…”