A case study for identifying the potential challenges of water resources in the Yilan area of Taiwan: using an adaptive water footprint approach.

Yilan is the main agricultural production area of northern Taiwan, and most of the freshwater in this area is used for the irrigation of rice; however, this area lacks lakes and reservoirs for reserving and balancing supply and demand of surface water. Accordingly, the abundance of groundwater in Yilan plays a crucial role for water supplying. This case study aims to disclose the hidden and potential crisis ignored in Yilan area on its water resources by the water footprint (WF) approach, which consists of blue, green, and grey water-use components; meanwhile, three essential climatic factors temperature, rainfall, and sunshine hours are discussed for examining and identifying their influences. This study adaptively modified a top-down scheme initiated by Hoekstra and Hung 2002, Hoekstra 2003) to properly make estimations of the WF on the basis of current data situation and local condition of this case study area. The quantitative analysis results show that the total average order of magnitude of the WF of rice in Yilan was approximately estimated to around 8000 m t, which has a comparative disadvantage and is around six times as many as the estimation on average of global, on a decadal basis after the millennium. Notably, it reveals an extravagant water-using attitude and a situation of oversupply in Yilan since this area tends to suppose water supply from the groundwater is abundant and unlimited. In addition, the blue and green water-use components over the crop period are directly and evidently influenced by rainfall, sunshine hours, and temperature. The grey water-use component will inevitably lead a catastrophic impact due to an excessive utilization of chemicals, fertilizers, and pesticides, in case the temperature keeps rising as a result of global warming and extreme weather conditions caused by the climate change. The potential challenges of freshwater resources and an inefficient as well as a carefree water-using attitude in this case study have been proved to drive the risk and need to take strategic precautions because of the gradually rising temperature, sunshine hours, and declining of the normal rainfall.