Surface water resources and climate change

Abstract

Water accumulated or ~owing on the surface of earth is considered as surface water. The water on the surface can originate from rains or from groundwater. Surface water resource is that part of the surface water stock which can be drawn on for various uses of water. In order to be aware of surface water resource, it is necessary to understand the magnitude, quality, and status with respect to spatial and temporal occurrence, ownership, allocations etc. Therefore research on surface water resources would require searching for knowledge or carrying out systematic investigations to establish facts about surface water. It is often necessary to identify limits of search and this depends on the users of the facts about surface water. In case of an abundant surface water resource, one might be satisfied with facts having only the order of magnitude, but when the resource is scarce, it is very important to dig deeper to seek detailed facts. This surfaces the need to conduct good research. The key to good research is systematic investigations in order to establish facts which would in turn enable either establishment of a present practice or understanding the need for improvement of a present practice. Climate change impacts are a key area of concern especially when water is the underlying theme. Though there is a factor of uncertainty about the potential climate change and its impacts, anticipated challenges from climatic change including the changes to precipitation and its pattern, changes to irrigation demands, changes to soil moisture due to temperature variations, changes to quantities evaporated from irrigated lands and irrigation reservoirs have been reasonably recognised. There is a higher confidence in projected patterns of warming and other regional-scale climate change features, including changes in wind patterns, precipitation and some aspects of extremes'. It is projected that crop yields could decrease up to 30% in Central and South Asia by the mid-21 st century. Taken together and considering the influence of rapid population growth and urbanisation, the risk of hunger is projected to remain very high in several developing countries''. It is also stated with very high confidence that water resource in many small islands is likely to be seriously compromised. As a result of climate change such islands are likely to experience water stress and predictions show reduced rainfall in summer. Hence it is unlikely that demand will be met during low rainfall periods. Increased rainfall in winter will be unlikely to compensate, due to a lack of storage and high runoff during storrns''. 68 The present work targets to identify and assess the research work that had been conducted on surface water and climate change of Sri Lanka through a review of selected literature. In case of assessing research, an important issue is to identify the reliability of results. Good research is expected to contain independent, objective results and analysis, which reflects reality. A research result to be reliable, a reader should be provided with a clear description of the used data and the quality of such data, along with an adequate description of the research methodology used for data collection and analysis. A good research would provide evidence of referencing thereby building reader confidence with respect to the sufficiency of 136 background work':". The present review is an attempt to capture the adequacy of surface water resources and climate research and associated reporting in a responsible manner.