Variations in the Total Dynamic Head (TDH) used in the selection of borehole pumps creates a situation where there is no single duty point but a range of duty points that move between a maximum and a minimum value.
Strategic Water Source Areas are defined as areas of land that either: (a) supply a disproportionate quantity of mean annual surface water runoff in relation to their size; or (b) have high groundwater recharge and where the groundwater forms a nationally important resource; or (c) areas that meet both criteria (a) and (b).
Around 2.5 to 3 billion people worldwide don’t have access to clean water. There are at least another 1.5 billion in developed countries who may have access to clean water, but don’t trust its quality. This article explains why smart policies are key to solving the world’s clean water problems.