Concerns about food security and apprehensions of future water scarcity are common to all the countries in the world. This paper focuses on the water issue between India and Bangladesh. Crisscrossed by the rivers and streams, Bangladesh is a water-abundant country with low-per capital water availability. Almost 94% of the water resources of the country originate beyond its borders, and that 54 rivers and streams flow into Bangladesh from India.

River flow response to the changing climate is a major concern in the Himalayan region. Present understanding regarding the impact of glacier shrinkage on the river flow variations is summarized in the IPCC 2007, which stated that "as these glaciers retreat due to global warming, river flows are increased in the short term, but the contribution of glacier melt will gradually decrease over the next few decades" and "the enhanced melting of glaciers leads at first to increased river runoff and discharge peaks and an increased melt season" (IPCC, 2007).

General Circulation Models (GCMs) are tools designed to simulate time series of climate variables globally, accounting for effects of greenhouse gases in the atmosphere. They are good at continental and hemispherical spatial scales and incorporate a large proportion of the complexity of the global systems.

In this study, a general methodology is presented in order to use the downscaled output from a RCM (Regional Climate Models) directly in a hydrologic model for evaluating the impact of climate change on water resources. The hydrologic model used is the Soil and Water Assessment Tool (SWAT). The study area is a part of the Chaliyar River Basin in Kerala, India.

Hydrological modelling of large river catchments is a challenging task for water resources engineers due to its complexity in collecting and handling of both spatial and non-spatial data such as rainfall, gauge discharges, and topographic parameters.

The true costs of the Belo Monte Hydroelectric Project, planned for the Xingu River in the Brazilian Amazon, will be much higher than dam proponents admit, according to a new independent review by a panel of 40 specialists. The panel found that the dam would have serious consequences for the region, its inhabitants, and ecosystems of the Amazon rainforest.

As far as water goes, climate change changes everything. Past experience of rainfall, snowfall, runoff and streamflow is no longer a reliable guide for the future. We'll all be affected, but especially small farmers and the poor and marginalized, who have the least ability to protect themselves against the depredations of droughts, floods and food shortages.