摘要：Shortage in supply of water for potable and non-potable applications and exponential world population increase is a strong constrain to Human Development Index and social-economic advancement in Nigeria. ClimGen (Version 4.1.05) was used to simulate and create large dataset of annual rainfall depth. Generated average annual rainfall from 1430 mm to 1600 mm was subjected to varying roof plan surfaces of 250 m2; 500 m2; 1000 m2; and 2000 m2 respectively. Simulation analysis showed that an average of 5,300m3 of rainwater was harvestable and this value of water could only meet water demand of 170 people annually. The relationship of roof plan surface (RPS) and collected rainwater is very strong with R2= 0.84 and 0.95 respectively. Again, the volume of groundwater withdrawal increased from 12.4×104m3 to 32.7×104m3, this could only meet an annual water demand for 10,480 people representing about 6.2% of the population in Auchi. This development reveals that water supply from the alternative sources could not meet up to 6.3% of total water demand in Auchi and increasing water availability and accessibility to about 65%(31.3×105m3) coverage requires integrated rainwater harvesting system and technically-based groundwater exploration mechanism.
